Keyword: electron
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MOYGB1 Status and Future Strategy for Advanced High Power Microwave Sources for Accelerators klystron, cavity, operation, linac 12
 
  • F. Gerigk
    CERN, Geneva, Switzerland
 
  The need for more energy efficient high power microwave devices for accelerator applications continues to increase. This is important for development of cost effective accelerator designs that are coming up in the near future. Efforts are already in place to design new devices that could stretch the limits of RF power conversion to the highest levels possible. Devices including new technologies and design innovations like multi beam, increased number of cavities designs are being considered. Advances in the application of solid state amplifiers to accelerators are also being realized. This invited talk will cover the recent advances and status of such efforts. It will discuss future needs and a strategy for pursuing these efforts on a faster time scale for the benefit of the accelerator community.  
slides icon Slides MOYGB1 [11.575 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOYGB1  
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MOYGB2 The LCLS-II: A High Power Upgrade to the LCLS cavity, linac, undulator, cryomodule 18
 
  • J.N. Galayda
    SLAC, Menlo Park, California, USA
 
  Funding: The work is supported by DOE under grant No. DE-AC02-76SF00515
The LCLS-II is an upgrade of the LCLS X-ray FEL based on a 4 GeV superconducting RF linac. The LCLS-II is designed to produce 100's of Watts of X-rays from 200 eV up to 5 keV. The linac uses 1.3 GHz 9-cell cavities processed using the N2-doping technique and will be the first large scale CW SCRF linac with a Q of roughly 3x1010 at a gradient of 16 MV/m. The injector which will be commissioned in spring 2018, is based on the normal conducting CW RF APEX gun developed at LBNL. The LCLS-II will have two undulators: the soft X-ray undulator is a 39 mm period hybrid PM with an adjustable vertical gap to cover the range from 200 eV to 1.5 keV and hard X-ray undulator is a novel adjustable horizontal gap hybrid PM undulator with 26 mm period to generate vertically polarized X-rays from 1 to 5 keV. The talk will review the performance goals as well as the hardware fabrication.
 
slides icon Slides MOYGB2 [11.367 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOYGB2  
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MOZGBD1 Towards Full Performance Operation of SwissFEL FEL, experiment, photon, laser 24
 
  • T. Schietinger
    PSI, Villigen PSI, Switzerland
 
  SwissFEL is the new X-ray free-electron laser facility at the Paul Scherrer Institute (PSI) in Switzerland. It was inaugurated in December 2016 and saw its first pilot experiments at the end of 2017. We describe the commissioning steps leading to the first phase of pilot experiments and outline the plans towards reaching nominal performance levels in 2018.  
slides icon Slides MOZGBD1 [11.391 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBD1  
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MOZGBD2 FEL Performance Achieved at European XFEL FEL, photon, MMI, undulator 29
 
  • M. Scholz
    DESY, Hamburg, Germany
 
  The European XFEL has achieved first lasing by mid-2017 and first user experiments started by the end of that year. This invited talk describes the status of this facility, presenting highlights from the construction and commissioning, outlining experience from early operation, and discussing potential future developments.  
slides icon Slides MOZGBD2 [18.822 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBD2  
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MOZGBD5 A Proposal for Coherent Hard X-Ray Generation Based on Two-Stage EEHG FEL, laser, linac, radiation 38
 
  • Z.T. Zhao, J.H. Chen, C. Feng, Z. Wang, K.Q. Zhang
    SINAP, Shanghai, People's Republic of China
 
  A two stage echo-enabled harmonic generation (EEHG) scheme to produce coherent hard X-rays is presented. Electron bunchs of quite different lengths are separately used in each stage of EEHG and a monochromator is employed to purify the radiation from the first stage for seeding the second one. Theoretical analysis and 3D simulations show that the proposed scheme can generate fully coherent hard X-ray pulses directly from a conventional UV seed laser.  
slides icon Slides MOZGBD5 [7.330 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBD5  
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MOZGBE1 Development of Gas Stripper at RIBF acceleration, plasma, target, heavy-ion 41
 
  • H. Imao
    RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama, Japan
 
  Charge strippers are almost inevitable for accelerations in heavy-ion accelerator complex. The fixed solid strip-pers including carbon-foil strippers are difficult to be used in on-going or upcoming new-generation in-flight RI beam facilities, e.g., RIBF (RIKEN, Japan), FAIR (GSI, Germany), FRIB (NSCL/MSU, US), HIAF (IMP, China) and RAON (RISP, Korea). The He gas stripper developed at RIBF is the first successful stripper significantly be-yond the applicable limit of the fixed carbon-foil strip-pers. We discuss the development of the gas strippers at RIBF and overview the related new-generation strippers being developed in the world.  
slides icon Slides MOZGBE1 [11.797 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBE1  
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MOZGBE5 Results on the FCC-hh Beam Screen at the KIT Electron Storage Ring KARA photon, experiment, radiation, vacuum 55
 
  • L.A. Gonzalez, V. Baglin, P. Chiggiato, C. Garion, M. Gil Costa, R. Kersevan
    CERN, Geneva, Switzerland
  • I. Bellafont, F. Pérez
    ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
  • S. Casalbuoni, E. Huttel
    KIT, Eggenstein-Leopoldshafen, Germany
 
  Funding: * The European Circular Energy-Frontier Collider Study (EuroCirCol) project has received funding from the European Union's Horizon 2020 research and innovation programme under grant No 654305.
In the framework of the EuroCirCol collaboration* (work package 4 "Cryogenic Beam Vacuum System"), the fabrication of 3 FCC-hh beam-screen (BS) prototypes has been carried out with the aim of testing them at room temperature at the Karlsruhe Institute of Technology (KIT) 2.5 GeV electron storage ring KARA (KArlsruhe Research Accelerator). The 3 BS prototypes will be tested on a beamline installed by the collaboration, named as BEam Screen TEstbench EXperiment (BESTEX). KARA has been chosen because its synchrotron radiation (SR) spectrum, photon flux and power, match the one foreseen for the 50+50 TeV FCC-hh proton collider. Each of the 3 BS prototypes, 2 m in length, implement a different design feature: 1) baseline design (BD), with electro-deposited copper and no electron-cloud (EC) mitigation features; 2) BD with set of distributed cold-sprayed anti-EC clearing electrodes; 3) BD with laser-ablated anti-EC surface texturing. We present here the results obtained so far at BESTEX and the comparison with extensive montecarlo simulations of the expected outgassing behavior under synchrotron radiation.
The information herein only reflects the views of its authors and the European Commission is not responsible for any use that may be made of the information.
 
slides icon Slides MOZGBE5 [4.318 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBE5  
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MOZGBF3 40 Years of Electron Cooling at CERN proton, antiproton, experiment, gun 69
 
  • G. Tranquille
    CERN, Geneva, Switzerland
 
  For nearly 40 years electron cooling has been used extensively on the storage rings of the CERN accelerator complex for the accumulation of ions or for the improvement of beam quality for precision experiments. Since the first cooling experiments on ICE the coolers have evolved to incorporate the latest advances in electron cooling technology and many unique experiments have also been performed when the coolers are not used for everyday operation. The trapping of anti-hydrogen atoms and more recently lead-lead and proton-lead ion collisions in the LHC have been made possible thanks to cooling in the AD and cooling and accumulation of lead ions in the LEIR respectively. The next cooler to be built at CERN will be installed on ELENA and will operate at electron energies below 350 eV. Many challenges lie ahead in operating at such a low energy with minimum perturbation to the storage ring. The present AD cooler, which has already seen two re-incarnations, will also be replaced with a new state-of-the-art device operating at higher energies in order to improve the quality of the antiproton beam in this ring.  
slides icon Slides MOZGBF3 [14.902 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBF3  
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MOPMF006 Test of Stepwise Electron Bunch Replacement in eRHIC Using an Electron Lens in RHIC emittance, proton, experiment, simulation 95
 
  • W. Fischer, M.R. Costanzo, A.V. Fedotov, X. Gu, A. Marusic, M.G. Minty, C. Montag, Y. Tan, P. Thieberger
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by U.S. DOE under contract No DE-AC02-98CH10886 with the U.S. Department of Energy.
The electron-ion collider eRHIC requires an electron bunch replacement about every second to maintain both high luminosity and polarization. If the bunch can be replaced in several steps, the requirements for both the electron gun and the electron accelerator are greatly reduced due to the reduced bunch charge. However, a stepwise replacement of electron bunches in eRHIC will give rise to transient effects from the beam-beam interaction that will lead to emittance growth. Such a scheme was tested using one of the RHIC electron lenses with a multiple step increase of the electron current. The test provides an order-of-magnitude estimate of the effect without any further mitigating measures.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF006  
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MOPMF011 Beam-Beam Issues With Two Interaction Points in eRHIC proton, detector, simulation, luminosity 102
 
  • Y. Luo, M. Blaskiewicz, A. He, C. Montag, V. Ptitsyn
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
In this article, we study the beam-beam interaction related issues with two interaction points in the current eRHIC ring-ring design. We carried out strong-strong beam-beam simulation in a 2-d bunch intensity scan. We observed coherent beam-beam instability and emittance blowup with 2 collisions per turn at lower bunch intensities than the case with only 1 collision per turn. To deliver collisions to the two experiments simultaneously, we proposed a new bunch filling pattern to avoid 2 collisions per turn for any electron or proton bunch. We proved that the parasitic beam-beam effect with the new bunch filling pattern is negligible.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF011  
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MOPMF012 Study of Crabbed Collision in eRHIC With a Combination of Strong-Strong and Weak-Strong Simulations simulation, proton, cavity, luminosity 105
 
  • Y. Luo, G. Bassi, M. Blaskiewicz, W. Fischer, Y. Hao, C. Montag, V. Ptitsyn, V.V. Smaluk, F.J. Willeke
    BNL, Upton, Long Island, New York, USA
  • J. Qiang
    LBNL, Berkeley, California, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
In the present design of the future electron-ion collider eRHIC at the Brookhaven National Laboratory, a crossing angle of 22~mrad between the electron and proton orbits at the interaction region is adopted. To compensate the geometric luminosity loss, a local compensation scheme with two sets of crab cavities for each beam is considered. In this article, we first carry out strong-strong beam-beam simulation to study possible coherent beam-beam instability. Under the assumption of no coherent beam-beam motion, we then carry out a weak-strong beam-beam simulation to determine the long-term stability of the proton beam with the equilibrium electron beam sizes extracted from the strong-strong beam-beam simulation.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF012  
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MOPMF013 eRHIC EIC: Plans for Rapid Acceleration of Polarized Electron Bunch at Cornell Synchrotron polarization, synchrotron, resonance, acceleration 108
 
  • F. Méot, E.C. Aschenauer, H. Huang, C. Montag, V. Ptitsyn, V.H. Ranjbar, E. Wang, Z. Zhao
    BNL, Upton, Long Island, New York, USA
  • I.V. Bazarov, D. L. Rubin
    Cornell University, Ithaca, New York, USA
  • L. Cultrera, G.H. Hoffstaetter, K.W. Smolenski, R.M. Talman
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • D. Gaskell, O. Glamazdin, J.M. Grames
    JLab, Newport News, Virginia, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
An option as an injector into the polarized-electron storage ring of eRHIC EIC is a rapid-cycling synchrotron (RCS). Cornell's 10 GeV RCS injector to CESR presents a good opportunity for dedicated polarized bunch rapid-acceleration experiments, it can also serve as a test bed for source and polarimetry developments in the frame of the EIC R&D, as polarized bunch experiments require disposing of a polarized electron source, and of dedicated polarimetry in the linac region and in the RCS proper. This is as well an opportunity for a pluri-disciplinary collaboration between Laboratories. This paper is an introduction to the topic, and to on-going activities towards that EIC R&D project.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF013  
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MOPMF014 Polarization at eRHIC Electron Storage Ring, an Ergodic Approach polarization, simulation, lattice, storage-ring 112
 
  • F. Méot
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Based on considerations of ergodicity of the dynamical system of an electron bunch at equilibrium, the preservation of polarization in an electron storage ring is estimated from the tracking of a very limited number of electrons. This has a substantial impact on required High Power Computing resources, in noticeable contrast with the method generally used that tracks tens of electron bunches, each comprised of thousands of particles, for several thousands of turns. It is also shown that a minimum number of tracking turns is required in order to ensure the numerical convergence of the linear regressions that yield depolarizing time constant values from tracking, in both methods.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF014  
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MOPMF029 FCC-hh transverse impedance budget impedance, injection, feedback, laser 149
 
  • S. Arsenyev, D. Schulte
    CERN, Geneva, Switzerland
  • O. Boine-Frankenheim
    GSI, Darmstadt, Germany
 
  Contributions of different machine elements of the proposed Future Circular Collider (FCC-hh) impedance budget are calculated based on beam stability considerations. For each element (the beamscreen, the collimators, etc), effective impedances are calculated at the injection energy and at the collision energy for considered instabilities. The considered instabilities include the transverse coupled bunch instability (TCBI) and the transverse mode coupling instability (TMCI). Limitations to each total effective impedance are estimated and the critical points in the impedance budget are determined.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF029  
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MOPMF031 Modelling Wake Impedance of a Rough Surface in Application to the FCC-hh Beamscreen impedance, coupling, laser, vacuum 157
 
  • S. Arsenyev, D. Schulte
    CERN, Geneva, Switzerland
 
  The inner surface of the future circular collider (FCC-hh) beamscreen is proposed to be laser-treated in order to mitigate the electron cloud build-up. However, the rough structure of the treated surface can result in unwanted impedance increase, potentially leading to the transverse mode coupling instability (TMCI). Three models have been adopted to estimate the wake impedance of a beamscreen with a rough surface. The models use the resistive wall formalism generalized for the case of an arbitrary surface impedance. The results apply to a beamscreen of a circular cross-section with the homogeneously rough inner surface for the case of ultrarelativistic particles. The free parameters of the models were fit into preliminary measurements of the surface resistivity, giving, as a result, a range of the real and the imaginary parts of the wake impedance.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF031  
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MOPMF053 Observations, Analysis and Mitigation of Recurrent LHC Beam Dumps Caused by Fast Losses in Arc Half-Cell 16L2 MMI, operation, vacuum, solenoid 228
 
  • J.M. Jimenez, D. Amorim, S. A. Antipov, G. Arduini, A. Bertarelli, N. Biancacci, B. Bradu, E. Bravin, G. Bregliozzi, K. Brodzinski, R. Bruce, X. Buffat, L.R. Carver, P. Chiggiato, S.D. Claudet, P. Collier, R. Garcia Alia, M. Giovannozzi, L. K. Grob, E.B. Holzer, W. Höfle, G. Iadarola, G. Kotzian, A. Lechner, T.E. Levens, B. Lindstrom, T. Medvedeva, A. Milanese, D. Mirarchi, E. Métral, D. Perini, S. Redaelli, G. Rumolo, B. Salvant, R. Schmidt, M. Valette, D. Valuch, J. Wenninger, D. Wollmann, C. Yin Vallgren, C. Zamantzas, M. Zerlauth
    CERN, Geneva, Switzerland
  • D. Amorim
    Université Grenoble Alpes, Grenoble, France
  • A.A. Gorzawski
    University of Manchester, Manchester, United Kingdom
  • L. Mether
    EPFL, Lausanne, Switzerland
 
  Recurrent beam dumps significantly perturbed the operation of the CERN LHC in the summer months of 2017, especially in August. These unexpected beam dumps were triggered by fast beam losses that built up in the cryogenic beam vacuum at the half-cell 16 left of LHC-IP2 and were detected either at that location but mainly in the collimation insertions. This contribution details the experimental observables (beam losses, coherent instabilities, heat load to cryogenic system, vacuum signals), the extent of the understanding of the beam loss and instability mechanisms and the mitigation steps and new settings that allowed recovering the luminosity performance of the LHC for the rest of the Run.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF053  
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MOPMF055 Update of the CLIC Positron Source positron, target, linac, simulation 236
 
  • Y. Han, L. Ma
    SDU, Shandong, People's Republic of China
  • C. Bayar
    Ankara University, Faculty of Sciences, Ankara, Turkey
  • S. Döbert, A. Latina, D. Schulte
    CERN, Geneva, Switzerland
 
  The baseline positron source of CLIC has been optimised for the 3 TeV c.o.m. energy. Now the first stage of the CLIC is proposed to be at 380 GeV. Recently, the positron transmission efficiency from the tungsten target to the damping rings injection has been improved by 2.5 times. This opened the possibility for an optimisation of the whole positron source, comprising the injector linacs, aimed at improving its performance and its overall power efficiency. In this paper the key parameters of the positron source, which include the current and the energy of the primary electron beam, the thickness of the crystal and amorphous tungsten targets, the distance between the two targets, the adiabatic matching device (AMD) and pre-injector linacs, are optimized to improve the overall power efficiency.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF055  
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MOPMF071 Polarization Studies for the eRHIC electron Storage Ring polarization, storage-ring, coupling, solenoid 292
 
  • E. Gianfelice-Wendt
    Fermilab, Batavia, Illinois, USA
  • S. Tepikian
    BNL, Upton, Long Island, New York, USA
 
  Funding: Manuscript authored by Fermi Res. All., LLC under Contr. No. DE-AC02-07CH11359 and Brookhaven Sc. Ass., LLC under Contr. No. DE-AC02-98CH10886 with the U.S. DOE, Office of Science, Office of HEP.
A hadron/lepton collider with polarized beams has been under consideration by the scientific community since some years, in the U.S. and Europe. Among the various proposals, those by JLAB and BNL with polarized electron and proton beams are currently under closer study in the U.S. Experimenters call for the simultaneous storage of electron bunches with both spin helicity. In the BNL based Ring-Ring design, electrons are stored at top energy in a ring to be accommodated in the existing RHIC tunnel. The transversely polarized electron beam is injected into the storage ring at variable energies, between 5 and 18 GeV. Polarization is brought into the longitudinal direction at the IP by a couple of spin rotators. In this paper results of first studies of the attainable beam polarization level and lifetime in the storage ring at 18 GeV are presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF071  
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MOPMF073 Rejuvenation of 7-Gev SuperKEKB Injector Linac positron, linac, emittance, injection 300
 
  • K. Furukawa, M. Akemoto, D.A. Arakawa, Y. Arakida, H. Ego, A. Enomoto, Y. Enomoto, T. Higo, H. Honma, N. Iida, M. Ikeda, H. Kaji, K. Kakihara, T. Kamitani, H. Katagiri, M. Kawamura, M. Kurashina, S. Matsumoto, T. Matsumoto, H. Matsushita, S. Michizono, K. Mikawa, T. Miura, F. Miyahara, H. Nakajima, K. Nakao, T. Natsui, M. Nishida, Y. Ogawa, Y. Ohnishi, S. Ohsawa, F. Qiu, I. Satake, M. Satoh, Y. Seimiya, A. Shirakawa, H. Sugimura, T. Suwada, T. Takenaka, M. Tanaka, N. Toge, Y. Yano, K. Yokoyama, M. Yoshida, R. Zhang, X. Zhou
    KEK, Ibaraki, Japan
 
  KEK injector linac has delivered electrons and positrons for particle physics and photon science experiments for more than 30 years. It was upgraded for the SuperKEKB project, which aims at a 40-fold increase in luminosity over the previous project KEKB, in order to increase our understanding of flavor physics beyond the standard model of elementary particle physics. SuperKEKB energy-asymmetric electron-positron collider with its extremely high luminosity requires a high current, low emittance and low energy spread injection beam from the injector. The electron beam is generated by a new type of RF gun, that provides a much higher beam current to correspond to a large stored beam current and a short lifetime in the ring. The positron source is another major challenge that enhances the positron bunch intensity from 1 to 4 nC by increasing the positron capture efficiency, and the positron beam emittance is reduced from 2000 μm to 10 μm in the vertical plane by introducing a damping ring, followed by the bunch compressor and energy compressor. The summary of the rejuvenation is reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF073  
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MOPMF074 Beam Phase Space Jitter and Effective Emittance for SuperKEKB Injector Linac emittance, target, linac, positron 304
 
  • Y. Seimiya, N. Iida, T. Kamitani, M. Satoh
    KEK, Ibaraki, Japan
 
  In SuperKEKB linac, stable high charged low emittance beam is necessary. Transported beam to SuperKEKB Main Ring (MR) must be stable to the extent that the beam can be injected inside MR acceptance. SuperKEKB requirement must be satisfied for emittance including beam phase space jitter, called as effective emittance. Large amplitude beam position jitter has been measured at linac end. We evaluated that the effect of the beam position jitter on effective emittance and investigated the source of the beam phase space jitter.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF074  
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MOPMF084 The Progress of CEPC Positron Source Design positron, target, linac, collider 319
 
  • C. Meng, X.P. Li, G. Pei, J.R. Zhang
    IHEP, Beijing, People's Republic of China
 
  Circular Electron-Positron Collider (CEPC) is a 100 km ring e+ e collider for a Higgs factory. The injector is composed of 10 GeV linac and 120 GeV booster. The linac of CEPC is a normal conducting S-band linac with frequency in 2856.75 MHz and provide electron and positron beam at an energy up to 10 GeV and repetition frequency in 100 Hz. The positron source of CEPC is composed of target, flux concentrator, pre-accelerating section and beam separation system. The detailed design of each section of positron source will be presented and discussed, meanwhile the start-to-end dynamic simulation results will be presented also in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF084  
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MOPMK010 Study Progress of the Coupling Resonance of the Crab Crossing Scheme in Electron-Ion Collider luminosity, synchrotron, simulation, cavity 368
 
  • Y. Hao
    FRIB, East Lansing, USA
  • Y. Luo, V. Ptitsyn
    BNL, Upton, Long Island, New York, USA
  • J. Qiang
    LBNL, Berkeley, California, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Crab crossing scheme is essential collision scheme to achieve high luminosity for the future electron-ion collider (EIC). The bunch length effect of the ion beam cannot be ignored even when cooling is present compared with the wavelength of the crab cavity, therefore, the nonlinear dependence of the crabbing kick may present a challenge to the beam dynamics of the ion beam, hence an impact to the luminosity lifetime. In this paper, we present the result of numerical beam dynamics studies of the crab crossing scheme. The result indicates that there is a special coupling resonance in the nonlinear relation of the crab crossing scheme of the EIC, which dominates the luminosity degradation. And we will discuss the possible remedies for such resonance.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK010  
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MOPMK011 VEPP-5 Injection Complex: New Possibilities for BINP Electron-Positron Colliders positron, injection, collider, gun 371
 
  • Yu. Maltseva, A.V. Andrianov, K.V. Astrelina, V.V. Balakin, A.M. Batrakov, O.V. Belikov, D.E. Berkaev, M.F. Blinov, D. Bolkhovityanov, A. Butakov, E.V. Bykov, N.S. Dikansky, F.A. Emanov, A.R. Frolov, V.V. Gambaryan, K. Gorchakov, Ye.A. Gusev, S.E. Karnaev, G.V. Karpov, A.S. Kasaev, E. Kenzhbulatov, V.A. Kiselev, S. Kluschev, A.A. Kondakov, I. Koop, I.E. Korenev, N.Kh. Kot, V.R. Kozak, A.A. Krasnov, S.A. Krutikhin, I.V. Kuptsov, G.Y. Kurkin, N.N. Lebedev, A.E. Levichev, P.V. Logatchov, A.A. Murasev, V. Muslivets, D.A. Nikiforov, An.A. Novikov, A.V. Ottmar, A.V. Pavlenko, I.L. Pivovarov, V.V. Rashchenko, Yu. A. Rogovsky, S.L. Samoylov, N. Sazonov, A.V. Semenov, D.B. Shwartz, A.N. Skrinsky, A.A. Starostenko, D.A. Starostenko, A.G. Tribendis, A.S. Tsyganov, S.P. Vasichev, S.V. Vasiliev, V.D. Yudin, I.M. Zemlyansky, A.N. Zhuravlev
    BINP SB RAS, Novosibirsk, Russia
  • A.V. Andrianov, V.V. Balakin, F.A. Emanov, I. Koop, A.A. Krasnov, A.E. Levichev, D.A. Nikiforov, A.V. Pavlenko, Yu. A. Rogovsky, D.B. Shwartz, A.A. Starostenko
    NSU, Novosibirsk, Russia
  • A.I. Mickailov
    Budker INP & NSU, Novosibirsk, Russia
  • A.G. Tribendis
    NSTU, Novosibirsk, Russia
 
  VEPP-5 Injection Complex (IC) is designed to supply BINP RAS colliders with high energy electron and positron beams. Recently constructed K-500 beam transfer line connects IC to both VEPP-4M and VEPP-2000 colliders. IC two collider operation was successfully performed in 2016. Nowadays, research on improvement of IC productivity is carried out, in particular 10.94 MHz RF cavity instead of 700 MHz one was installed and a new electron gun installation is expected to be this summer. Moreover, longitudinal beam profile measurements in IC damping ring using a streak-camera were carried out. Operation experience of IC and results of longitudinal beam profile measurements are reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK011  
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MOPMK012 Electron Cloud Studies in FCC-ee collider, simulation, quadrupole, vacuum 374
 
  • E. Belli
    Sapienza University of Rome, Rome, Italy
  • P. Costa Pinto, G. Rumolo, T.F. Sinkovits, M. Taborelli
    CERN, Geneva, Switzerland
  • M. Migliorati
    INFN-Roma1, Rome, Italy
 
  Electron cloud effects are one of the most critical aspects for the LHC and the future circular colliders. In the frame of the electron-positron collider FCC-ee, an estimation of the electron cloud build up in the machine will be discussed in this paper. A preliminary evaluation of the heat load in the arc components and interaction region magnets will be presented, together with possible mitigation strategies.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK012  
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MOPMK015 Development of a Bunched-Beam Electron Cooler for the Jefferson Lab Electron-Ion Collider linac, kicker, gun, cathode 382
 
  • S.V. Benson, Y.S. Derbenev, D. Douglas, F.E. Hannon, A. Hutton, R. Li, R.A. Rimmer, Y. Roblin, C. Tennant, H. Wang, H. Zhang, Y. Zhang
    JLab, Newport News, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S.DOE Contract No. DE-AC05-06OR23177.
Jefferson Lab is in the process of designing an electron-ion collider with unprecedented luminosity at a 65 GeV center-of-mass energy. This luminosity relies on ion cooling in both the booster and the storage ring of the accelerator complex. The cooling in the booster will use a conventional DC cooler similar to the one at COSY. The high-energy storage ring, operating at a momentum of up to 100 GeV/nucleon, requires novel use of bunched-beam cooling. We will present a new design for a Circulator Cooler Ring for bunched-beam electron cooling. This requires the generation and transport of very high-charge magnetized bunches, acceleration of the bunches in an energy recovery linac, and transfer of these bunches to a circulating ring that passes the bunches 11 times through the proton or ion beam inside cooling solenoids. This design requires the suppression of the effects of space charge and coherent synchrotron radiation using shielding and RF compensation.
 
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MOPMK016 Calculations of Beam-Beam Effect and Luminosity for Crab Dynamics Simulations in JLEIC luminosity, simulation, collider, beam-beam-effects 386
 
  • H. Huang, V.S. Morozov, A.V. Sy
    JLab, Newport News, Virgina, USA
 
  Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contracts DE-AC05-06OR23177 and DE-AC02-06CH11357.
Crab crossing is an integral part of the Jefferson Lab Electron-Ion Collider (JLEIC) design to achieve high luminosity while meeting the detection and physics pro-gram requirements. The crab crossing scheme provides a head-on beam-beam collision for beams with a nonzero crossing angle. Simulations of crabbing dynamics currently do not include beam-beam effects. We describe a framework for accurate simulation of beam-beam effects on crabbing dynamics by applying a numerical calculation of the Bassetti-Erskine analytic solution to symplectic particle tracking codes. The numerical calculation is benchmarked against the analytic solution by calculating the luminosity reduction for several colliding beam scenarios. Benchmarking results show good agreement be-tween the numerical calculation and analytic solution, paving the way for implementation of the beam-beam kick to Elegant tracking simulations.
 
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MOPML006 Multi-Stage Electron Cooling Scheme for JLEIC emittance, proton, simulation, collider 397
 
  • H. Zhang, S.V. Benson, Y.S. Derbenev, Y. Roblin, Y. Zhang
    JLab, Newport News, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357.
JLEIC is the future electron ion collider under design at Jefferson Lab, which will provide a luminosity up to 1034 cm-2s-1. Electron cooling is essential for JLEIC to overcome the intrabeam scattering effect, reduce the ion beam emittance and thus achieve the high luminosity. The cooling time is approximately in proportion to the square of the energy and the 6D emittance. To avoid the difficulty of cooling the ion beam with large emittance at high energy, a multi-stage cooing scheme was designed for JLEIC. The ion beam was cooled at the low energy to reduce the emittance. Then it was ramped up to the collision energy. During the collision, electron cooling is implemented to maintain the emittance and the luminosity. Simulations for proton beam and lead ion beam at various stages are presented in this paper.
 
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MOPML008 JLEIC Electron Ring Dynamic Aperture with Non-linear Field Errors dynamic-aperture, emittance, lattice, sextupole 404
 
  • Y.M. Nosochkov, Y. Cai
    SLAC, Menlo Park, California, USA
  • F. Lin, V.S. Morozov, G.H. Wei, Y. Zhang
    JLab, Newport News, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under US DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357. Work supported by the US DOE Contract DE-AC02-76SF00515.
We present results of dynamic aperture study for the updated electron ring lattice of the Jefferson Lab Electron-Ion Collider (JLEIC). The lattice design features low emittance arcs with local compensation of sextupole non-linear effects, and low emittance non-linear chromaticity correction sections. Dynamic aperture tracking simulations are performed to evaluate the effects of non-linear field errors, the sensitivity to betatron tune, and the impact of momentum error. Dynamic aperture is also evaluated with the measured PEP-II field errors. Preliminary tolerances to the non-linear field errors in the Final Focus quadrupoles are estimated.
 
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MOPML013 Progress on Preliminary Conceptual Study of HIEPA, a Super Tau-Charm Factory in China collider, positron, factory, luminosity 422
 
  • Q. Luo, D.R. Xu
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  Funding: Work supported by National Natural Science Foundation of China 11375178 and the Fundamental Research Funds for the Central Universities, Grant No WK2310000046.
As the most successful tau-charm factory of the world, BEPC II will celebrate its 10th birthday this year and will finish its historical mission in the next decade. Because of its very important role in high energy phys-ics study, BEPC II will certainly need a successor, a new tau-charm collider. This paper discusses the feasi-bility of a greenfield next generation tau-charm collid-er named HIEPA. The luminosity of this successor is about 5×1034 cm−2s−1 pilot and 1×1035cm-2s−1 nominal, with the electron beam longitudinally polarized at the IP. The general scheme of the accelerators and the beam parameters are shown. Several key technologies such as beam polarization and beam emittance diag-nostics are also discussed.
 
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MOPML022 Development of Travelling Wave Accelerating Structure for a 10 MeV E-Linac bunching, radiation, linac, simulation 443
 
  • J.H. Yang, Y. Yang
    CIAE, Beijing, People's Republic of China
  • G. Han
    China Institute of Atomic Energy, Beijing, People's Republic of China
 
  Electron irradiation processing is a vital application field of nuclear technology application. China Institute of Atomic Energy (CIAE) developed several 10 MeV high power electron irradiating accelerator successfully, promoting the development of high energy high power irradiating accelerator technology and electron irradiation processing in China. The paper introduced the development of a 10 MeV travelling wave accelerating tube. The tube operates at 2856 MHz in 2π/3 mode. The SUPERFISH and PARMELA are used for the physical design. Several methods are used for microwave parameter measurement and tuning. The high power test shows the beam energy is 10.3 MeV and average beam power is 24.3 kW.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML022  
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MOPML023 Very-High Energy Electron (VHEE) Studies at CERN's CLEAR User Facility experiment, simulation, scattering, proton 445
 
  • A. Lagzda, R.M. Jones
    UMAN, Manchester, United Kingdom
  • A. Aitkenhead, K. Kirkby, R. MacKay, M. Van Herk
    The Christie NHS Foundation Trust, Manchester, United Kingdom
  • R. Corsini, W. Farabolini
    CERN, Geneva, Switzerland
 
  Funding: Science and Technology Facilities Council (STFC) - United Kingdom
Here we investigate how inserts of various densities (0.001-2.2 g/cm3) affect the dose distribution properties of VHEE beams at ~150 MeV. A range variation comparison was also made with clinical proton beams using TOPAS/GEANT4 Monte Carlo simulations. In addition, we assess the viability of scattering foils for optimizing the size of VHEE beams for radiotherapy purposes. The experiments were conducted at CERN's CLEAR user facility.
 
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MOPML028 Accelerator Machines and Experimental Activities in the ENEA Frascati Particle Accelerators and Medical Application Laboratory radiation, experiment, proton, linac 460
 
  • M. Vadrucci, A. Ampollini, G. Bazzano, F. Borgognoni, P. Nenzi, L. Picardi, C. Ronsivalle, V. Surrenti, E. Trinca
    ENEA C.R. Frascati, Frascati (Roma), Italy
 
  Funding: Regione Lazio - TOP IMPLART Project
In the ENEA Frascati research center the APAM (Particle Accelerators and Medical Application) laboratory is devoted to the development of particle accelerators for medical applications. Two main facilities are operational. The TOP-IMPLART proton accelerator is a pulsed fully linear machine aimed at active intensity modulated proton therapy with a final energy of 150 MeV. The machine offers two beam extraction points: one at 3-7 MeV, on a vertical line, and the other one at 35 MeV, the maximum energy currently available, with a pulse current up to 35 μA, on the horizontal line. The REX (Removable target Electron X-ray) source consists of an electron standing wave LINAC generating a beam in the energy range of 3 to 5 MeV with a pulsed current of 0.2 A. This source can generate Bremsstrahlung X-ray beams using suitable converters (Pb, W, Ta). This paper describes the experimental results of satellite activities performed in these facilities in the fields of biology, dosimetry, electronics, PIXE spectroscopy and preservation of cultural heritage manufacts.
 
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MOPML029 A Portable X-ray Source Based on Dielectric Accelerators vacuum, target, shielding, solenoid 464
 
  • C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • S.P. Antipov, A. Kanareykin, R.A. Kostin
    Euclid Beamlabs LLC, Bolingbrook, USA
 
  Funding: The work has been supported by the U.S. Department of Homeland Security (DHS), Domestic Nuclear Detection Office (DNDO), under a competitively awarded contract No. HSHQDC-17-C-00007.
The portable low energy accelerator based X-ray sources have attractive applications in the non-destructive examination as a replacement of radiological gamma isotope sources. We are developing an inexpensive ultra-compact dielectric accelerator technology for low energy electron beams. The portability in the realm of this proposal is unprecedented ~ 1 ft3 volume with ~ 50 lbs of weight. The use of ceramics makes the transverse size of the accelerating waveguide comparable to that of a pencil. Because of this size reduction, additional weight reduction of shielding becomes possible. The article will report on the progress of this project.
 
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MOPML030 Demonstration of a Tunable Electron Beam Chopper for Application in 200 kV stroboscopic TEM kicker, laser, experiment, controls 467
 
  • C.-J. Jing, S.V. Baryshev, A. Kanareykin, A. Liu, Y. Zhao
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • J.W. Lau
    NIST, Gaithersburg, Maryland, USA
  • D. Masiel, B. Reed
    Integrated Dynamic Electron Solutions, Pleasanton, California, USA
  • Y. Zhu
    BNL, Upton, Long Island, New York, USA
 
  Funding: The project is supported by the Office of Basic Energy Science of DOE through a Small Business Innovative Research grant #DE-SC0013121.
For the last several decades, time-resolved transmission electron microscopes (TEM) exploring the sub-microsecond timescale have relied on the photoemission technology to generate the single or train of electron bunches. However, the complexity of additional laser system and the availability of high repitition rate laser limit applications of the laser-driven approach. Lately we have made substantial progress towards pioneering a new kind of time-resolved TEM, complementary to the existing laser-based techniques. Using a tunable RF beam-chopper, we are able to retrofit an exsiting TEM providing a pulsed electron beam at a continuously tunable reptition rate up to 12GHz and a tunable bunch length. In the article we will briefly discuss the working principle and experimental progress to date.
 
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MOPML031 Highlights of Accelerator Activities in France on Behalf of the Accelerator Division of the French Physics Society linac, laser, proton, operation 470
 
  • J.-L. Revol
    ESRF, Grenoble, France
  • S. Chel
    CEA/IRFU, Gif-sur-Yvette, France
  • B. Cros
    CNRS LPGP Univ Paris Sud, Orsay, France
  • N. Delerue
    LAL, Orsay, France
  • E. Giguet
    ALSYOM, Versailles, France
  • V. Le Flanchec
    CEA/DAM, Bruyères-le-Châtel, France
  • L.S. Nadolski
    SOLEIL, Gif-sur-Yvette, France
  • L. Perrot
    IPN, Orsay, France
  • A. Savalle
    GANIL, Caen, France
  • T. Thuillier
    LPSC, Grenoble Cedex, France
 
  The French Physical Society is a non-profit organization working to advance and diffuse the knowledge of physics. Its Accelerators division contributes to the promotion of accelerator activities in France. This paper presents the missions and actions of the division, high-lighting those concerning young scientists. A brief presentation of the laboratories, institutes, and facilities that are the main actors in the field is given. Significant ongoing and planned projects in France are described, including medical applications. Main French contributions in inter-national projects are then listed. Finally, cultural and technical relationships between industry and laboratories are discussed.  
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MOPML047 Diversified Application of ILC photon, neutron, scattering, FEL 502
 
  • Y. Iwashita
    Kyoto ICR, Uji, Kyoto, Japan
  • T. Hayakawa
    QST, Tokai, Japan
  • N. Kawamura, S. Makimura, K. Mishima, D. Nomura, K. Shimomura, S. Yamamoto, T. Yamazaki
    KEK, Ibaraki, Japan
 
  ILC will be a very powerful accelerator complex. It has not only the high power energetic electron beam but also positron and photon beams. In addition to these beams, large cryogenic plants are equipped together with various utility facilities. Some suggestions on the assumption of availability of ILC are offered from various fields. These discussions will be reported.  
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MOPML049 Generation of 1-MeV Quasi-Monochromatic Gamma-Rays for Precise Measurement of Delbrück Scattering by Laser Compton Scattering laser, scattering, experiment, photon 508
 
  • H. Zen, T. Kii, H. Ohgaki
    Kyoto University, Kyoto, Japan
  • M. Fujimoto, M. Katoh, E. Salehi
    UVSOR, Okazaki, Japan
  • T. Hayakawa, T. Shizuma
    QST, Tokai, Japan
  • M. Katoh
    Sokendai - Okazaki, Okazaki, Aichi, Japan
  • J. Koga
    National Institutes for Quantum and Radiological Science and Technology, Kyoto, Japan
  • E. Salehi
    AUT, Tehran, Iran
 
  Delbrück scattering is the elastic scattering of photons by the electromagnetic field of an atomic nucleus, as a consequence of vacuum polarization. The isolated measurement of Delbrück scattering has not been performed because of interference with other elastic scattering processes. It was recently discovered that, using linearly polarized photons, Delbrück scattering can be measured nearly independently of the other scattering processes*. In order to perform a proof of principle experiment, a quasi-monochromatic gamma-ray beam with a maximum photon energy of 1 MeV has been generated at the UVSOR facility by colliding a CO2 laser with a 750-MeV electron beam. A preliminary experiment has been performed with 0.5-W laser power and 1-mA electron beam current. As a result, the measured gamma-ray flux was evaluated as 0.0006 photon/eV/mA/W/s around the peak energy of 1 MeV. If we accept 20 percent energy spread, in case of a 100-W CO2 laser colliding with a 300 mA electron beam, approximately 4 x 106-photons/s gamma-rays could be obtained. This flux is sufficiently high for the proof of principle experiment.
*J.K. Koga and T. Hayakawa, Phys. Rev. Lett. 118, 204801 (2017).
 
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MOPML051 First Performance Calculations for the Very High Energy Electron Radiation Therapy Experiment at PRAE radiation, experiment, proton, photon 516
 
  • A. Faus-Golfe
    LAL, Orsay, France
  • R. Delorme, Y. Prezado
    IMNC, Orsay, France
  • V. Favaudon, C. Fouillade, S. Heinrich, A. Mazal, A. Patriarca, P. Poortmans, P. Verrelle
    Institut Curie - Centre de Protonthérapie d'Orsay, Orsay, France
  • A. Hrybok
    National Taras Shevchenko University of Kyiv, Radiophysical Faculty, Kiev, Ukraine
 
  The Platform for Research and Applications with Electrons (PRAE) project aims at creating a multidisciplinary R&D platform at the Orsay campus, joining various scientific communities involved in radiobiology, subatomic physics, instrumentation, particle accelerators and clinical research around a high-performance electron accelerator with beam energies up to 70 MeV and later 140 MeV, in order to perform a series of unique measurements and challenging R&D. In this paper we will report the first optics design and performance evaluations of such a multidisciplinary machine, focusing on Very High Energy Electrons (VHEE) innovative Radiation Therapy (RT) applications in particular by allowing Grid and FLASH methodologies, which are likely to represent a major breakthrough in RT. Functional specifications include beam intensities to produce dose rates from 2 Gy/min to 100Gy/sec, beam sizes with diameters from 0.5 mm to 10 cm or more of homogeneous beams and monitoring devices with accuracy in the order of 1-2% for single or multiple beams and single or multiple fractions in biological and ppreclinical applications. High energies (>140 MeV) would be also needed for GRID therapy.  
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MOPML052 The Path to Compact, Efficient Solid-State Transistor-Driven Accelerators cavity, linac, impedance, simulation 520
 
  • D.C. Nguyen, C.E. Buechler, G.E. Dale, R.L. Fleming, M.A. Holloway, J.W. Lewellen, D. Patrick
    LANL, Los Alamos, New Mexico, USA
  • V.A. Dolgashev, E.N. Jongewaard, E.A. Nanni, J. Neilson, A.V. Sy, S.G. Tantawi
    SLAC, Menlo Park, California, USA
 
  Funding: Research presented in this work is supported by (LANL) Laboratory Directed Research and Development 20170521ER and by (SLAC) Department of Energy contract DE-AC02-76SF00515.
Small, lightweight, few-MeV electron accelerators that can operate with low-voltage power sources, e.g., solid-state transistors running on 50 VDC, instead of high-voltage klystrons, will provide a new tool to enhance existing applications of accelerators as well as to initiate new ones. Recent advances in gallium nitride (GaN) semiconductor technologies * have resulted in a new class of high-power RF solid-state devices called high-electron mobility transistors (HEMTs). These HEMTs are capable of generating a few hundred watts at S-, C- and X-bands at 10% duty factor. We have characterized a number of GaN HEMTs and verified they have suitable RF characteristics to power accelerator cavities **. We have measured energy gain as a function of RF power in a single low-beta C-band cavity. The HEMT powered RF accelerators will be compact and efficient, and they can operate off the low-voltage DC power buses or batteries. These all-solid-state accelerators are also more robust, less likely to fail, and are easier to maintain and operate. In this poster, we present the design of a low-beta, 5.1-GHz cavity and beam dynamics simulations showing continuous energy gain in a ten-cavity C-band prototype.
* See for example, http://www.wolfspeed.com/downloads/dl/file/id/463/product/174/cghv59350.pdf
** J.W. Lewellen et al., Proceedings of LINAC2016, Paper MO3A03
 
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MOPML055 Preliminary Physics Design of a Linac with the Variable Energy for Industrial Applications linac, gun, beam-loading, simulation 530
 
  • Zh. X. Tang
    USTC, Hefei, Anhui, People's Republic of China
  • L. Wang, D.R. Xu
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  This paper describes the physics design of a S-band (2856 MHz) linear accelerator (linac) with variable energy tuning. The system consists of a DC gun for generating electron, prebuncher for velocity modulation and two travelling wave (TW) accelerating sections for acceleration. The accelerating structure is a 2'Ð/3 mode constant gradient TW structure, which comprises TW buncher cells, followed by uniform cells. The structure is designed to accelerate 45 keV electron beam from the electron gun to 3.2 MeV, and then 10 MeV. An important feature of the TW linac is that the RF output power of the first linac is as the RF input power of the second linac. Three dimensional transient simulations of the accelerating structure along with the input and output couplers have been performed to explicitly demonstrate this feature. Beam dynamics is performed to calculate the beam parameter.  
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MOPML056 Evidence of the Electron-Screened Oppenheimer Philips Reactions 162Er(d, n)163Tm or 162Er(p,γ)163Tm in Deuterated Materials Subjected to a Low-Energy Photon Beam neutron, proton, experiment, target 533
 
  • T.L. Benyo, A. Chait, L.P. Forsley, M. Pines, V. Pines, B.M. Steinetz
    NASA Glenn Research Center, Cleveland, USA
 
  NASA GRC has investigated electron-screening of deuterated metals using MV electron linear accelerators (LINACs). GRC found that repeatable sub-threshold nuclear reactions may have occurred resulting in nuclear products observed via witness-material neutron activation using high purity germanium (HPGe) gamma spectroscopy and liquid scintillator spectroscopy. The suspected path of creation may be the result of electron-screened Oppenheimer-Phillips reactions or Mirror Oppenheimer-Phillips reactions. Evidence of 162Er(d, n)163Tm or 162Er(p,γ)163Tm has been shown with the appearance of gamma peaks coinciding with 163Tm with a published ' life of 22 minutes from samples containing deuterated erbium exposed to a photon beam. Both of these reactions are a variation of the Oppenheimer-Phillips nuclear reaction. Evidence of the reactions have been detected by an HPGe gamma detection system and witnessed within gamma spectra collected from deuterated materials subjected to a nominally 1.95 MeV photon beam. This paper describes the theory behind the proposed reactions, the experiments conducted at GRC, and the experimental evidence of the suspected creation of the 163Tm isotope.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML056  
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MOPML058 Comparison of Water Absorbed Dose for Photons of Linac and Traceability System for Radiotherapy in China photon, controls, radiation, linac 537
 
  • K. Wang, S. Jin, Z. Wang, J. Zhang
    National Institute of Metrology, Beijing, People's Republic of China
 
  National Institute of Metrology (NIM) developed the standards of the absorbed dose to water for high-energy photon and electron beams, to support the PSDL and SSDL calibration capability in China. After the measurement of absorbed dose to water for 6, 10, and 25 MV photons of linac, NIM took part the BIPM. RI(I).K6 comparison with the Bureau International des Poids et Mesures (BIPM). The tissue phantom ratio (TPR20,10) of 6MV and 10MV photons were measured by IBA CC13 chamber and Keithley 6517B with different output dose of the Linac, and also calculated by the dose ratio (D20⁄D10) with the formula in IAEA TRS-398 report. TPR20,10 measured directly is 0.3% larger than calculated by the dose ratio D20⁄D10 . The absorbed dose to water is measured by water calorimeter with the combined standard uncertainty of 0.35%. The discrepancy of absorbed dose to water measured separately by open and sealed vessel is 0.2% at 10MV. The K6 comparison was done, the results reported as ratios of the NIM and the BIPM evaluations (and with the combined standard uncertainties given in parentheses), are 0.9917(60) at 6 MV, and 0.9941(59) at 10 MV. The quality correction factor KQ of usual used chamber was measure directly, and it is 0.3%~0.7% smaller than the data in the IAEA TRS-398 report. The typical chamber-to-chamber variations of the dose obtained with the IAEA TRS-277, TRS-398 and AAPM TG-51 were between 0.2% and 1.0% for the different photon beams. The variations of the dose obtained with IAEA TRS-398 and chambers calibrated directly by megavoltage photons were between 0.1% to 0.8%. The new standard can achieve the traceability of water absorbed dose for MV photons and will significantly reduce the uncertainty of ion chamber calibrations for Chinese radiotherapy centers.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML058  
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MOPML060 Self-Consistent Simulation and Optimization of Space-Charge Limited Thermionic Energy Converters simulation, space-charge, cathode, feedback 543
 
  • N.M. Cook, J.P. Edelen, C.C. Hall
    RadiaSoft LLC, Boulder, Colorado, USA
  • J.-L. Vay
    LBNL, Berkeley, California, USA
 
  Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics under Award Number DE-SC0017162.
Thermionic energy converters (TEC) are an attractive technology for modular, efficient transfer of heat to electrical energy. The steady-state dynamics of a TEC are a function of the emission characteristics of the cathode and anode, an array of intra-gap electrodes and dielectric structures, and the self-consistent dynamics of the electrons in the gap. Proper modeling of these devices requires self-consistent simulation of the electron interactions in the gap. We present results from simulations of these devices using the particle-in-cell code Warp, developed at Lawrence Berkeley National Lab. We consider the role of individual energy loss mechanisms in reducing device efficiency, including kinetic losses, radiative losses, and dielectric charging. We discuss the implementation of an external circuit model to provide realistic feedback. Lastly, we illustrate the potential to use nonlinear optimization to maximize the efficiency of these devices by examining grid transparency.
 
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MOPML066 Ultrafast Mega-electron-volt Gas-Phase Electron Diffraction at SLAC National Accelerator Laboratory gun, vacuum, laser, experiment 556
 
  • X. Shen, R.K. Li, X.J. Wang, S.P. Weathersby, J. Yang
    SLAC, Menlo Park, California, USA
 
  Funding: This work was supported in part by the U.S. Department of Energy Contract No. DE-AC02-76SF00515, and the SLAC UED/UEM Initiative Program Development Fund.
Ultrashort mega-electron-volt (MeV) electron beams from radio-frequency (rf) photoinjectors have recently attracted strong interests for application in ultrafast gas-phase electron diffraction (UGED). Such high-brightness electron beams are capable of providing 100-fs level temporal resolution and sub-Angstrom level spatial resolution to capture the ultrafast structural dynamics from photoexcited gas molecules. To experimentally demonstrate such an ultrafast electron scattering instrument, a high performance UGED system has been commissioned at SLAC National Accelerator Laboratory. The UGED instrument produces 3.7 MeV electron beams with 2 fC beam charge at 180-Hz repetition rate. The temporal resolution is characterized to be 150 fs full-width-at-half-maximum (FWHM), while the spatial resolution is measured to be 0.76 Å FWHM. The UGED instrument also demonstrates outstanding performance in vacuum, rf, and electron beam pointing stability. Details of the performance of the SLAC MeV UGED system is reported in this paper.
 
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MOPML067 9/6 MeV European S-band Linac Structure for Container Inspection System at RTX and KAERI coupling, linac, bunching, gun 560
 
  • P. Buaphad, H.D. Park, S. Song
    RTX, Daejeon, Republic of Korea
  • P. Buaphad, Y. Joo
    University of Science and Technology of Korea (UST), Daejeon, Republic of Korea
  • P. Buaphad, S.C. Cha, Y. Joo, Y. Kim, H.R. Lee
    KAERI, Jeongeup-si, Republic of Korea
 
  Recently, demands on low energy electron linear accelerators (linacs) for industrial applications are rapidly growing. Their beam energies are lower than 20 MeV, and they require a compact, cheap, and stable accelerator system. For the Container Inspection System (CIS), KAERI successfully developed a 9/6 MeV American S-band (= 2856 MHz) linac with a 5 MW klystron in 2013. To reduce the cost of the RF source, recently, KAERI and RTX also have been developing another 9/6 MeV European S-band (= 2998 MHz) linac by using a magnetron with a lower RF power of about 3.1 MW. Its accelerating structure is designed to be operated in π/2 mode by coupling 13 accelerating cells together through 12 side-coupling cells. The CST Microwave Studio is used for electromagnetic simulations and optimization of the accelerating structure. After various optimizations, a shunt impedance of 84 MΩ/m is obtained at π/2 mode frequency of 2998.31 MHz. In this paper, we describe design concept, optimization, and RF measurement of the new 9/6 MeV European S-band linac structure. Then, we compare it with our old American S-band linac structure.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML067  
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MOPML068 Training the Next Generation of Accelerator Experts network, FEL, laser, synchrotron 564
 
  • C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
 
  Funding: Work supported by the European Union under grant agreements no 215080, 289191, 289485, 675265 and 721559.
Close collaboration between academia, research centres and industry has turned out to be crucial for the advancement of accelerator science and technology. It is also ideal for providing an efficient training of the next generation of particle accelerator experts and for linking the global accelerator community. Five international research and training networks (DITANET, oPAC, LA3NET, OMA and AVA) have been initiated and coordinated by the University of Liverpool/Cockcroft Institute since 2007. These networks have provided training to almost 100 Fellows from all over the world and organised dozens of international schools, topical workshops and international conferences for the accelerator community. The research activities of the networks have led to hundreds of journal publications and conference proceedings. This contribution presents the best practice in establishing such international collaborative projects, how to establish successful links between sectors and countries, and highlights the main research results that resulted from the research programs.
 
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MOPML070 Thermal and Stress Analysis of an X-Ray Target for 6 MeV Medical Linear Accelerators target, simulation, site, photon 572
 
  • Z.H. Wang, H.B. Chen, J. Shi, H. Zha
    TUB, Beijing, People's Republic of China
 
  We present an optimal design of an X-ray target for 6 MeV medical linear accelerators using FLUKA simula-tions. The target is composed of high-atomic number tungsten and high-thermal conductivity copper, corre-sponding water-cooling system is showed too. Further-more, we analyse the temperature and thermal stress re-sponses of the target under transient thermal loads using Ansys Code. For 6 MeV electron beam with 100 uA cur-rent, the results show that the target can achieve 1014 cGy/min at 1meter in front of the target. Within 100 ms, the maximum temperature reaches 512 °C under pulsed heating source with 250 Hz frequency and 1' duty cycle and the number of cycles to failure is estimated as 5.8·108.  
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TUXGBD3 Ideas and Concepts for Future Electron Ion Colliders luminosity, collider, polarization, detector 590
 
  • F.C. Pilat
    ORNL, Oak Ridge, Tennessee, USA
 
  Different versions of future electron-ion colliders have been proposed by Brookhaven National Laboratory (BNL) and Thomas Jefferson National Laboratory (JLAB), one based on colliding protons in a ring with electrons from an Energy Recovery Linac (ERL), the other two based on ring-ring colliders. To attain the luminosity goal strong hadron cooling is required, as could be provided with several proposed new cooling schemes. Polarization of both colliding beams is essential. This invited talk will compare the various designs and highlight some of the novel ideas and concepts.  
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TUXGBE1 Status and Prospects for the AWAKE Experiment plasma, proton, wakefield, experiment 595
 
  • M. Turner
    CERN, Geneva, Switzerland
 
  The AWAKE Collaboration is pursuing a demonstration of proton-driven plasma wakefield acceleration of electrons. The AWAKE experiment uses a §I{400}{GeV/c} proton bunch from the CERN SPS, with a rms bunch length of 6-§I{15}{cm}, to drive wakefields in a §I10{m} long rubidium plasma with an electron density of 1014-1015cm-3. Since the drive bunch length is much longer than the plasma wavelength (λpe<§I{3}{mm}) for these plasma densities, AWAKE performed experiments to prove that the long proton bunch self-modulates in the plasma (2017). The next step is to demonstrate acceleration of electrons in the wakefields driven by the self-modulated bunch (2018). We summarize the concept of the self-modulation measurements and describe the plans and challenges for the electron acceleration experiments.  
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TUXGBE2 Study of Ultra-High Gradient Acceleration in Carbon Nanotube Arrays plasma, acceleration, wakefield, experiment 599
 
  • J. Resta-López, A.S. Alexandrova, V. Rodin, Y. Wei, C.P. Welsch, G.X. Xia
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • Y. M. Li, Y. Zhao
    UMAN, Manchester, United Kingdom
 
  Solid-state based wakefield acceleration of charged particles was previously proposed to obtain extremely high gradients on the order of 1 − 10 TeV/m. In recent years the possibility of using either metallic or carbon nanotube structures is attracting new attention. The use of carbon nanotubes would allow us to accelerate and channel particles overcoming many of the limitations of using natural crystals, e.g. channeling aperture restrictions and thermal-mechanical robustness issues. In this paper, we propose a potential proof of concept experiment using carbon nanotube arrays, assuming the beam parameters and conditions of accelerator facilities already available, such as CLEAR at CERN and CLARA at Daresbury. The acceleration performance of carbon nanotube arrays is investigated by using a 2D Particle-In-Cell (PIC) model based on a multi-hollow plasma. Optimum experimental beam parameters and system layout are discussed.  
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TUXGBE3 Status of Plasma-Based Experiments at the SPARC_LAB Test Facility plasma, experiment, focusing, emittance 603
 
  • E. Chiadroni, D. Alesini, M.P. Anania, M. Bellaveglia, A. Biagioni, F.G. Bisesto, E. Brentegani, F. Cardelli, G. Costa, M. Croia, D. Di Giovenale, G. Di Pirro, M. Ferrario, F. Filippi, A. Gallo, A. Giribono, A. Marocchino, L. Piersanti, R. Pompili, S. Romeo, J. Scifo, V. Shpakov, A. Stella, C. Vaccarezza, F. Villa
    INFN/LNF, Frascati (Roma), Italy
  • A. Cianchi
    INFN-Roma II, Roma, Italy
  • M. Marongiu, A. Mostacci
    Sapienza University of Rome, Rome, Italy
  • J.B. Rosenzweig
    UCLA, Los Angeles, California, USA
  • A.R. Rossi
    Istituto Nazionale di Fisica Nucleare, Milano, Italy
  • A. Zigler
    The Hebrew University of Jerusalem, The Racah Institute of Physics, Jerusalem, Israel
 
  The current activity of the SPARC LAB test-facility is focused on the realization of plasma-based acceleration experiments with the aim to provide accelerating field of the order of several GV/m while maintaining the overall quality (in terms of energy spread and emittance) of the accelerated electron bunch. The current status of such an activity is presented, together with results related to the applicability of plasmas as focusing lenses in view of a complete plasma-based focusing, accelerating and extraction system.  
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TUXGBE4 Beam Quality Limitations of Plasma-Based Accelerators plasma, laser, injection, acceleration 607
 
  • A. Ferran Pousa, R.W. Aßmann
    DESY, Hamburg, Germany
  • A. Martinez de la Ossa
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
 
  Plasma-based accelerators are a promising novel technology that could significantly reduce the size and cost of future accelerator facilities. However, the typical quality and stability of the produced beams is still inferior to the requirements of Free Electron Lasers (FELs) and other applications. We present here our recent work in understanding the limitations of this type of accelerators, particularly on the energy spread and bunch length, and possible mitigating measures for future applications, like the plasma-based FEL in the EuPRAXIA design study.  
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TUXGBF2 Higher-Order-Mode Effects in Tesla-Type Superconducting RF Cavities on Electron Beam Quality HOM, cavity, FEL, detector 612
 
  • A.H. Lumpkin, N. Eddy, D.R. Edstrom, P.S. Prieto, J. Ruan, R.M. Thurman-Keup
    Fermilab, Batavia, Illinois, USA
  • K. Bishofberger, B.E. Carlsten
    LANL, Los Alamos, New Mexico, USA
  • O. Napoly
    CEA/DSM/IRFU, France
 
  Funding: *Work at Fermilab supported by FRA, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Dept. of Energy. **Work at LANL supported by U.S. Dept. of Energy through the LANL/LDRD Program.
We report the direct observations of the correlation of higher order modes (HOMs) generated by off-axis electron beam steering in TESLA-type SCRF cavities and sub-macropulse beam centroid shifts (with the concomitant effect on averaged beam size and emittance). The experiments were performed at the Fermilab Accelerator Science and Technology (FAST) facility using its unique configuration of a PC rf gun injecting beam into two separated 9-cell cavities in series with corrector magnets and beam position monitors (BPMs) located before, between, and after them. The ~100-kHz oscillations with up to 300-μm amplitudes at downstream locations were observed in a 3-MHz micropulse repetition rate beam with charges of 500 and 1000 pC/b, although the effects were much reduced at 100 pC/b. The studies were based on HOM detector circuitry targeting the first and second dipole passbands, rf BPM bunch-by-bunch data, and imaging cameras viewing multi-slit images for emittance assessments at 33 MeV. Initial calculations reproduced a key feature of the phenomena. In principle, these results may be scaled to cryomodule configurations of major accelerator facilities.
 
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TUYGBD3 eRHIC Design Status hadron, luminosity, storage-ring, proton 628
 
  • V. Ptitsyn, G. Bassi, J. Beebe-Wang, J.S. Berg, M. Blaskiewicz, A. Blednykh, J.M. Brennan, S.J. Brooks, K.A. Brown, K.A. Drees, A.V. Fedotov, W. Fischer, D.M. Gassner, W. Guo, Y. Hao, A. Hershcovitch, H. Huang, W.A. Jackson, J. Kewisch, C. Liu, H. Lovelace III, Y. Luo, F. Méot, M.G. Minty, C. Montag, R.B. Palmer, B. Parker, S. Peggs, V.H. Ranjbar, G. Robert-Demolaize, S. Seletskiy, V.V. Smaluk, K.S. Smith, S. Tepikian, P. Thieberger, D. Trbojevic, N. Tsoupas, W.-T. Weng, F.J. Willeke, H. Witte, Q. Wu, W. Xu, A. Zaltsman, W. Zhang
    BNL, Upton, Long Island, New York, USA
  • E. Gianfelice-Wendt
    Fermilab, Batavia, Illinois, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The electron-ion collider eRHIC aims at a luminosity around 1034cm-2sec-1, using strong cooling of the hadron beam. Since the required cooling techniques are not yet readily available, an initial version with a peak luminosity of 3*1033cm-2sec-1 is being developed that can later be outfitted with strong hadron cooling. We will report on the current design status and the envisioned path towards 1034cm-2sec-1 luminosity.
 
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TUYGBE2 CBETA, the 4-Turn ERL with SRF and Single Return Loop linac, gun, SRF, cryomodule 635
 
  • G.H. Hoffstaetter, N. Banerjee, J. Barley, A.C. Bartnik, I.V. Bazarov, D.C. Burke, J.A. Crittenden, L. Cultrera, J. Dobbins, S.J. Full, F. Furuta, R.E. Gallagher, M. Ge, C.M. Gulliford, B.K. Heltsley, R.P.K. Kaplan, V.O. Kostroun, Y. Li, M. Liepe, W. Lou, C.E. Mayes, J.R. Patterson, P. Quigley, D.M. Sabol, D. Sagan, J. Sears, C.H. Shore, E.N. Smith, K.W. Smolenski, V. Veshcherevich, D. Widger
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • J.S. Berg, S.J. Brooks, C. Liu, G.J. Mahler, F. Méot, R.J. Michnoff, M.G. Minty, S. Peggs, V. Ptitsyn, T. Roser, P. Thieberger, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, F.J. Willeke, H. Witte
    BNL, Upton, Long Island, New York, USA
  • D. Douglas
    JLab, Newport News, Virginia, USA
  • J.K. Jones
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • D. Jusic
    Cornell University, Ithaca, New York, USA
  • D.J. Kelliher
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
  • B.C. Kuske, M. McAteer, J. Völker
    HZB, Berlin, Germany
 
  Funding: Supported by NSF award DMR-0807731, DOE grant DE-AC02-76SF00515, and NYSERDA.
A collaboration between Cornell University and Brookhaven National Laboratory has designed and is constructing CBETA, the Cornell-BNL ERL Test Accelerator on the Cornell campus. The ERL technology that has been prototyped at Cornell for many years is being used for this new accelerator, including a DC electron source and an SRF injector Linac with world-record current and normalized brightness in a bunch train, a high-current linac cryomodule optimized for ERLs, a high-power beam stop, and several diagnostics tools for high-current and high-brightness beams. BNL has designed multi-turn ERLs for several purpose, dominantly for the electron beam of eRHIC, its Electron Ion Collider (EIC) project and for the associated fast electron cooling system. Also in JLEIC, the EIC designed at JLAB, an ERL is envisioned to be used for electron cooling. The number of transport lines in an ERL is minimized by using return arcs that are comprised of a Fixed Field Alternating-gradient (FFA) design. This technique will be tested in CBETA, which has a single return for the 4-beam energies with strongly-focusing permanent magnets of Halbach type. The high-brightness beam with 150~MeV and up to 40~mA will have applications beyond accelerator research, in industry, in nuclear physics, and in X-ray science. Low current electron beam has already been sent through the most relevant parts of CBETA, from the DC gun through both cryomodules, through one of the 8 similar separator lines, and through one of the 27 similar FFA structures. Further construction is envisioned to lead to a commissioning start for the full system early in 2019.
 
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TUYGBE4 Optically-pumped Polarized H and 3 He++ Ion Sources Development at RHIC injection, polarization, ion-source, solenoid 644
 
  • A. Zelenski, G. Atoian, E.N. Beebe, A. Poblaguev, D. Raparia, J. Ritter
    BNL, Upton, Long Island, New York, USA
  • J.D. Maxwell, R. Milner, M. Musgrave
    MIT, Cambridge, Massachusetts, USA
 
  The RHIC Optically-pumped Polarized H Ion Source (OPPIS) upgrade with the atomic beam hydrogen injector and the He-ionizer cell was commissioned for operation in the Run-2013. The use of the high brightness primary proton source resulted in higher polarized beam intensity and polarization delivered for injection to Linac-Booster-AGS-RHIC accelerator complex. The proposed polarized 3He++ acceleration in RHIC and future electron- ion col-lider (eRHIC) will require about 2·1011 ions in the source pulse. A new technique had been proposed for production of high intensity polarized 3He++ ion beam. It is based on ionization and accumulation of the 3He gas (polarized by optical-pumping and metastability-exchange technique in the high magnetic field of a 5.0 T) in the Electron Beam Ion Source (EBIS). We present a status of the 3He++ ion source development.  
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TUYGBF3 An EBIS-Based Low-Energy Accelerator for Fine-Focussed Ion Beams ion-source, target, acceleration, emittance 647
 
  • M. Schmidt, P. Laux, G.H. Zschornack
    DREEBIT, Großröhrsdorf, Germany
 
  Technologies based on focused ion beams have become indispensable for research institutions as well as commercial laboratories and high-tech production facilities (micro- and nanotechnology, semiconductor technology). We report on a compact setup combining an Electron Beam Ion Source (EBIS), a Wien filter for ion species separation, and a fine focusing ion acceleration column capable of producing ion beams with beam diameters in the micrometer range at ion beam energies up to the MeV range. Almost all elements of the periodic system can be injected into the EBIS to produce a broad spectrum of ion charge states with only one ion source. The beam energy of a selected ion species can easily be varied by changing the electric potential of the EBIS drift tube in which the ions are generated, resulting in different implantation depths in various solids. We present studies on beam diameter and emittance, available charge states, and SEM imaging as application.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUYGBF3  
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TUYGBF4 Design and Simulation Tools for the High-Intensity Industrial Rhodotron Electron Accelerator cavity, dipole, gun, cathode 651
 
  • W.J.G.M. Kleeven, M. Abs, J. Brison, E. Forton, J. M. Hubert, J. Walle
    IBA, Louvain-la-Neuve, Belgium
 
  The Rhodotron is a compact industrial CW recirculating electron accelerator producing intense beams with energies in the range from about 1 to 10 MeV. RF-frequencies are in the range of 100 to 400 MHz. Average beam powers can range from 10 kW to almost 1 MW, depending of the specific type of Rhodotron. Main industrial applications are polymer cross-linking, sterilization, food treatment and container security scanning. Recently, RF pulsing was developed to reduce the average wall power dissipation, thus reducing drastically the energy consumption. Pulsing also permits smaller cavities and higher energies up to 40 MeV, opening the way to applications such as mobile irradiators, or isotopes production by photonuclear reactions, thus offering a compact and high beam duty alternative to linacs. This paper concentrates on some crucial design tools and methods for transverse and longitudinal optics studies, particle tracking with space charge, beam formation studies in the electron gun and dipole magnet design.  
slides icon Slides TUYGBF4 [11.952 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUYGBF4  
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TUPAF030 Electron Cloud Build Up for LHC Sawtooth Vacuum Chamber vacuum, photon, simulation, synchrotron 744
 
  • G. Guillermo Cantón, F. Zimmermann
    CERN, Geneva, Switzerland
  • G.H.I. Maury Cuna, E. D. Ocampo
    Universidad de Guanajuato, División de Ciencias e Ingenierías, León, Mexico
 
  At high proton-beam energies, beam-induced synchrotron radiation is an important source of heating, of beam-related vacuum pressure increase, and of primary photoelectrons, which can give rise to an electron cloud. For the arcs of LHC a sawtooth pattern had been imprinted on the horizontally outward side  of the vacuum chamber in order to locally absorb synchrotron radiation photons without dispersing them all around the chamber. Using the combination of the codes Synrad3D and PyCLOUD we examine the effect of realistic absorption distributions with and without sawtooth on the build up of electron clouds.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF030  
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TUPAF036 Studies of the Injection and Cooling Efficiency in LEIR Using the Longitudinal Schottky Spectrum injection, linac, diagnostics, pick-up 765
 
  • S. Hirlaender, R. Alemany-Fernández, H. Bartosik, N. Biancacci, V. Kain
    CERN, Geneva, Switzerland
 
  The CERN Low Energy Ion Ring (LEIR) has two main operational beams with their associated cycles, the so-called EARLY and the NOMINAL beam. The EARLY beam consists of a single injected pulse from the LINAC3 accelerator, whereas seven consecutive injections are accumulated, and electron cooled for the NOMINAL beam. In both cases, the longitudinal Schottky monitor allows assessing the longitudinal particle distribution during the cooling process on the injection plateau. A method has been established to analyze the Schottky signal, reconstruct the initial particle momentum distribution and derive relevant parameters such as the cooling time, energy off-set of injected and stacked beam or the momentum distribution of the lost beam. The variations of the obtained parameters and the impact on the LEIR performance will be addressed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF036  
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TUPAF039 Electron Cooling Simulation and Experimental Benchmarks at LEIR plasma, experiment, simulation, solenoid 776
 
  • A. Latina, H. Bartosik, N. Biancacci, R. Corsini, D. Gamba, S. Hirlaender, A. Huschauer
    CERN, Geneva, Switzerland
 
  A fast and accurate simulation of Electron Cooling has recently been implemented in the tracking code RF-Track. The implementation, which is based on a "hybrid kinetic" model, enables the simulation of a large variety of realistic scenarios, including imperfections such as gradients in the electron density, misalignments of electrons / ions / solenoidal fields, both in the static and in the dynamic regimes. Benchmarks of the simulations against measurements performed at LEIR, using Lead and Xenon ions, are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF039  
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TUPAF041 Residual Gas Ions Characterization from the REXEBIS detector, ISOL, rfq, experiment 784
 
  • N. Bidault, M.L. Lozano, J.A. Rodriguez
    CERN, Geneva, Switzerland
 
  The Isotope mass Separator On-Line DEvice (ISOLDE) is a user facility located at CERN where Radioactive Ion Beams (RIBs) are produced from proton collisions onto a target, mass separated and transported to user experimental stations either directly at low energy or after being post- accelerated, notably for nuclear physics studies. Prior to acceleration through the REX/HIE-ISOLDE linear acceler- ator, the ion beam is accumulated, bunched and cooled in a Penning trap (REXTRAP) and afterwards charge-bred in an Electron Beam Ion Source (REXEBIS). Multi-charged radioactive species of interest are then selected by a mass-to- charge (A/q) ratio separator dipole in the Low Energy Beam Transfer Line (LEBT). A method is presented to character- ize the Residual Gas Ion (RGI) background contamination for different operational conditions of the REXEBIS. More particularly, a discussion is held about the influence of the confinement time inside the charge-breeder on the residual gas spectrum. Finally, a method to identify sub-pico-Ampere contaminants is demonstrated.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF041  
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TUPAF049 Analysis of Loss Signatures of Unidentified Falling Objects in the LHC proton, operation, beam-losses, vacuum 814
 
  • L. K. Grob, M. Dziadosz, E.B. Holzer, A. Lechner, B. Lindstrom, R. Schmidt, D. Wollmann, C. Zamantzas
    CERN, Geneva, Switzerland
 
  Particulates in the LHC beam pipes can interact with the proton beams and cause significant beam losses. The "UFOs" (unidentified falling objects) hypothesis describes a particle falling into the beam, creating particle showers, being ionized and repelled. Though the signals of the beam loss monitors support this, many aspects remain unknown. Neither the source of the dust nor the release mechanism from the beam pipe are understood. The same holds for the forces involved in the interaction and the observed UFO rate reduction over the years. These open questions are approached from different angles. Firstly, a new data analysis tool was established featuring advanced raw data selection and statistical analysis. Results of this analysis will be presented. Secondly, dust samples were extracted from LHC components and analyzed to gain insight into the size distribution and material composition of the contamination. The performed observations and analysis lead to a better modelling of the UFO events and helped to understand the physics involved. The validated UFO models will be crucial in view of the high luminosity upgrade of the LHC (HL-LHC) and the Future Circular Collider (FCC).  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF049  
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TUPAF056 The CERN-ELENA Electron Cooler Magnetic System solenoid, alignment, gun, proton 842
 
  • G. Tranquille, L.V. Jørgensen
    CERN, Geneva, Switzerland
  • D. Luckin, R.J. Warner
    Tesla Engineering Limited, West-Sussex, United Kingdom
 
  Phase space compression of the antiproton beam in ELENA will be performed by a new electron cooler the performance of which is greatly influenced by the properties of the electron beam. Careful design of the electron gun electrodes, the efficient recuperation of the electrons in the collector and the quality of the guiding magnetic field ensure an optimal performance of the cooler. The ELENA cooler is a compact device incorporating an adiabatic expansion to reduce the electron beam temperature as well as electrostatic bending plates for efficient collection of the electron beam. The transverse components of the longitudinal field in the cooling section must be kept small (Bt/Bl ≤ 5x10-4) to ensure a minimal perturbation to the electron beam transverse temperature. The longitudinal field itself needs to be as low as possible such that the distortion to the closed orbit of the circulating ion beam due to the short 90° toroids is kept as small as possible. We present the solutions chosen to design and construct a magnetic system within the above constraints as well as the setup used to measure and optimise the magnetic field components.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF056  
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TUPAL041 Vacuum Accelerating Tube with Two Symmetrically Located Targets for Neutron Generation cathode, neutron, target, plasma 1097
 
  • V.I. Rashchikov, A.A. Isaev, A.E. Shikanov
    MEPhI, Moscow, Russia
 
  Original neutron generator* on the base of pulse accelerating vacuum tube with two targets, symmetrically located on the both sides of deuteron source is discussed. Two immersion lenses in front of each other uses as accelerating and focusing systems. Lenses cathodes are Faraday cups with targets for neutron production on the bottom. Symmetric ring magnetic elements cover immersion lenses for correcting focusing conditions. Computer simulation allows us to choose electrodes geometry and accelerating pulse value for electron flow from ion-electron emission oscillate between the targets and provide device operate as reflective triode. Estimations of neutron flow and spatio-temporal neutron field structure are done.
* Patent RF N2467526, 14.06.2011
 
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TUPAL042 On Possibility of Reflective Triode Uses for Thermonuclear Neutron Generation in Budker-Post Trap with Pulsed Magnetic Field plasma, neutron, proton, focusing 1100
 
  • V.I. Rashchikov, A.N. Didenko, A.A. Isaev, K.I. Kozlovskiy, V.L. Shatokhin, A.E. Shikanov, E.D. Vovchenko
    MEPhI, Moscow, Russia
 
  Scheme for thermonuclear neutron generation in compact Budker-Post trap with barrel-shaped pulsed magnetic field produced by two symmetrically located thin coils with diameter not exceed 0.05 m is proposed. During neutron generation in the trap simultaneously forms plasma which include hydrogen nuclides with density up to 1013 m-3 and two pulsed counter hydrogen nuclides flows accelerated in the diodes. Diodes consist of transparent anode with the form of sphere sector symmetrically covered by the same form grounded cathode. Diodes located symmetrically in front of each other, coaxially to magnetic trap. Computer simulation shows possibility to generate up to 1010 neutrons per pulse for deuterium-tritium compound in the diode system with transverse dimension ~0.1 m, amplitude and accelerating pulse duration 5.105 V and 100 nsec. The value of magnetic induction in the center of the trap should be approximately equal to 20 T.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL042  
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TUPAL043 Simulations of the Electron Column in IOTA plasma, proton, space-charge, simulation 1103
 
  • B.T. Freemire
    Northern Illinois University, DeKalb, Illinois, USA
  • S. Chattopadhyay
    Northern Illinois Univerity, DeKalb, Illinois, USA
  • M. Chung
    UNIST, Ulsan, Republic of Korea
  • C.S. Park
    Korea University Sejong Campus, Sejong, Republic of Korea
  • G. Penn
    LBNL, Berkeley, California, USA
  • V.D. Shiltsev, G. Stancari
    Fermilab, Batavia, Illinois, USA
 
  Funding: Work supported by the U.S. Department of Energy, Office of High Energy Physics, under Contract Nos. DE-AC02-07CH11359 and DE-AC02-05CH1123 and General Accelerator Research and Development Program
Future high current proton accelerators will need to minimize beam loss due to space-charge in order to achieve safe operation while achieving the desired physics goals. One method of space-charge compensation to be tested at the Integrable Optics Test Accelerator (IOTA) at Fermilab is the Electron Column. The concept for this device is to allow a circulating beam to ionize a small region of relatively high pressure residual gas, while using electric and magnetic fields to confine and shape the resulting plasma electrons. If the profile of the electrons is matched to the beam profile transversely and longitudinally, the electrons should counteract the space-charge force of the proton beam. Simulations of the IOTA proton beam circulating through the Electron Column have been performed, with the evolution of the electron plasma and its effect on the beam studied.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL043  
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TUPAL044 Technical Workings of the 6D Phase Measurement at SNS dipole, diagnostics, data-analysis, beam-transport 1107
 
  • B.L. Cathey
    ORNL RAD, Oak Ridge, Tennessee, USA
  • A.V. Aleksandrov, S.M. Cousineau, A.P. Zhukov
    ORNL, Oak Ridge, Tennessee, USA
 
  Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. This work has been partially supported by NSF Accelerator Science grant 1535312.
The Beam Test Facility (BTF) is a functional duplicate of the Spallation Neutron Source (SNS) frontend with a 2.5 MeV beam on which the first six-dimensional phase space measurement has been completed. This presentation will show the technical underpinnings involved in performing the 6D scan with the BTF. The first part will examine the diagnostic setup involving apertures, a screen, and a bunch shape monitor and how the integrated system functions. The next part will cover the scan logic used in the software. The last part will briefly discuss ongoing efforts to analyze 6D measurements and identify correlations.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL044  
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TUPAL062 Recent Developments for Cyclotron Extraction Foils at TRIUMF extraction, cyclotron, simulation, TRIUMF 1159
 
  • Y. Bylinskii, R.A. Baartman, P.E. Dirksen, Y.-N. Rao, V.A. Verzilov
    TRIUMF, Vancouver, Canada
 
  Funding: Funded under a contribution agreement with NRC (National Research Council Canada).
The TRIUMF 500 MeV H− cyclotron employs stripping foils to extract multiple beams for different experimental programs. The upgrades in foil material and foil holders lead to significant improvements in beam quality and foil life time, as well as reduction of Be-7 contamination originated in the foils. Thus, an accumulated beam charge extracted with a single foil increased from ~60 mA·hours to more than 500 mA·hours. A key role that lead to these advances was an understanding of the foil heating mechanism, major contribution to which is paid by the power deposition from electrons stripped by the foil. To further diminish this effect, we recently introduced a foil tilt from the vertical orientation that allows stripped electrons fast escape from the foil, well before losing their original momentum through the heat deposition. Other improvements were related to operational issues. Introduction of a "combo" foil consisting of wide portion and thin wire allowed both high and low intensity beam extraction without foils sacrifice. Deploying a wedge foil for extraction at 100 MeV helped reduction of beam intensity instabilities caused by beam vertical size and position fluctuations.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL062  
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TUPAL067 Accelerators Validating Antimatter Physics proton, antiproton, experiment, FEL 1167
 
  • C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
 
  Funding: This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 721559.
The Extra Low Energy Antiproton ring (ELENA) will be a critical upgrade to the unique Antiproton Decelerator facility at CERN and is currently being commissioned. ELENA will significantly enhance the achievable beam quality and enable new experiments. To fully exploit the discovery potential of this facility, advances are urgently required in numerical tools that can adequately model beam transport, life time and interaction, beam diagnostics tools and detectors to fully characterize the beam's properties, as well as in novel experiments that exploit the enhanced beam quality that ELENA will provide. These three areas form the scientific work packages of the new pan-European research and training initiative AVA (Accelerators Validating Antimatter physics). The project has received around 4M€ of funding and brings together universities, research centers and industry to train 15 Fellows through research in this area. This contribution presents the research results across AVA's three scientific work packages.
 
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TUPAL068 The Development of a Nw Fast Harmonic Kicker for the JLEIC Circulator Cooling Ring kicker, cavity, emittance, simulation 1171
 
  • G.-T. Park, F. Fors, J. Guo, R.A. Rimmer, H. Wang, S. Wang
    JLab, Newport News, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
After the first half-scale, 5 harmonic kicker cavity prototyping * for the JLEIC's CCR/ERL electron cooler and the beam dynamic simulation study of the 10-turn CCR **. The optimized circulation cooling turns has been changed to 11 and only 5 odd-harmonic modes from 86.6 MHz to 779.4 MHz plus a DC bias are needed for the harmonic RF kicker system. The new cavity design including the electromagnetic and thermal cooling optimization and its 11 turns beam bunch tracking simulation with the new numerology of RF deflecting voltages will be presented. Further design specifications for its RF harmonic drive and the broadband RF window, coupler and circulator component will be given for handling 5 kW of total RF power.
* Y, Huang, H. Wang et al., Physical Review Accelerators and Beams 19, 122001 (2016).
** Y. Huang, H. Wang et al., Physical Review Accelerators and Beams 19, 084201 (2016).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL068  
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TUPAL069 Experimental Demonstration of Ion Beam Cooling with Pulsed Electron Beam experiment, synchrotron, simulation, data-analysis 1174
 
  • Y. Zhang, A. Hutton, K. Jordan, T. Powers, R.A. Rimmer, M. F. Spata, H. Wang, S. Wang, H. Zhang
    JLab, Newport News, Virginia, USA
  • J. Li, X.M. Ma, L.J. Mao, M.T. Tang, J.C. Yang, X.D. Yang, H. Zhao, H.W. Zhao
    IMP/CAS, Lanzhou, People's Republic of China
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Cooling ion beams at high energy is presently considered for several ion colliders, in order to achieve high luminosities by enabling a significant reduction of emittance of hadron beams. Electron beam at cooling channel in a few to tens MeV can be accelerated by a RF/SRF linac, and thus using bunched electrons to cool bunched ions. To study such cooling process, the DC electron gun of EC35 cooler at the storage ring CSRm, IMP was modified by pulsing the grid voltage. A 0.07-3.5 micro-second pulse length with a repetition frequency of less than 250 kHz and synchronized with the ion revolution frequency was obtained. The first experimental demonstration of cooling of a coasting and bunched ion beam by a pulsed electron beam was carried out. Data analysis indicates the bunch length shrinkage and the momentum spread reduction of bunched 12C+6 ion beam as evidence of cooling. A longitudinal grouping effect of the coasting ion beam by the electron pulses has also been observed*. In this paper, we will present experimental results and comparison to the simulation modelling, particularly on the bunched electron cooling data after carefully analyzing the beam diagnostic signals.
* L.J. Mao et al., Experimental Demonstration of Electron Cooling with Bunched Electron Beam, TUP15, Proceedings of COOL2017, Bonn, Germany
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL069  
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TUPAL072 Dispersive Electron Cooling for JLEIC emittance, proton, scattering, coupling 1178
 
  • H. Zhang, Y.S. Derbenev, Y. Zhang
    JLab, Newport News, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357.
JLEIC is the electron ion collider under design at Jefferson Lab, which will provide a luminosity up to 1034 cm-2s−1. To reach the high luminosity, short ion and electron bunches with high charge density colliding in high frequency are proposed in JLEIC design. The high charge density of the ion beam leads to strong intrabeam scattering effect, which enlarges the ion beam emittance and ruins the luminosity if not mitigated. Magnetized electron cooling is implemented to overcome the intrabeam scattering effect and to reduce or maintain the ion beam emittance. In this paper, we discuss the redistribution of the cooling effects in the longitudinal and the transverse directions by introducing the dispersion of the ion beam in the cooling section. When the charge density of the cooling electron beam varies, the dispersion of the ion beam leads to an increase of the transverse cooling rate and a reduction of the longitudinal cooling rate, while the total decrement of the Courant-Snyder invariant of the ion beam increases. Both theoretical analysis and numerical calculation are presented.
 
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TUZGBD3 Beam Diagnostics for the APS MBA Upgrade feedback, diagnostics, undulator, controls 1204
 
  • N. Sereno, N.D. Arnold, R.W. Blake, A.R. Brill, H. Bui, J. Carwardine, G. Decker, L. Emery, T. Fors, P.S. Kallakuri, R.T. Keane, R.M. Lill, D.R. Paskvan, A.F. Pietryla, H. Shang, X. Sun, S. Veseli, J. Wang, S. Xu, B.X. Yang
    ANL, Argonne, Illinois, USA
 
  The Advanced Photon Source (APS) is currently in the preliminary design phase for a multi-bend acromat (MBA) lattice upgrade. Beam stability is critical where the requirements are driven from the beam size which is expected to approach 4 microns vertically at the insertion device (ID) source points. AC rms beam stability requirements are defined as 10 % the minimum source size at the ID in the band 0.01-1000 Hz. The vertical plane stability goal is the most ambitious requiring a stability of 400 nm at the ID source point. In addition, long term drift defined as motion over a seven day timescale can be no more than 1 micron. In order to achieve these demanding beam stability requirements, a suite of beam diagnostics will be required including rf BPMs, X-ray BPMs, a mechanical motion measurement system, beam size monitors and a real time orbit feedback system. In addition, a tune measurement system, transverse multi-bunch feedback system and current monitors are planned for the upgrade. We report on the beam diagnostics design and APS storage ring R&D results used to inform the design.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUZGBD3  
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TUZGBD5 Performance of Nanometre-Level Resolution Cavity Beam Position Monitors at ATF2 cavity, feedback, dipole, kicker 1212
 
  • T. Bromwich, D.R. Bett, N. Blaskovic Kraljevic, R.M. Bodenstein, P. Burrows, G.B. Christian, C. Perry, R.L. Ramjiawan
    JAI, Oxford, United Kingdom
  • S. Araki, A. Aryshev, T. Tauchi, N. Terunuma
    KEK, Ibaraki, Japan
  • P. Bambade, S. Wallon
    LAL, Orsay, France
  • S.W. Jang
    Korea University Sejong Campus, Sejong, Republic of Korea
 
  A system of three low-Q cavity beam position monitors (BPMs), installed in the interaction point (IP) region of the Accelerator Test Facility (ATF2) at KEK, has been designed and optimised for nanometre-level beam position resolution. The BPMs are used to provide an input to a low-latency, intra-train beam position feedback system deployed in single-pass, multi-bunch mode with the aim of demonstrating intra-train beam stabilisation on electron bunches of charge ~1 nC separated in time by 280 ns. In 2016 the BPM resolution was demonstrated to be below 50 nm using the raw measured vertical positions at the three BPMs. New results will be presented utilising integrated sampling of the raw waveforms, improved BPM alignment and modified cavities to demonstrate a vertical position resolution on the order of 20 nm.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUZGBD5  
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TUZGBE3 Towards Implementation of Laser Engineered Surface Structures for Electron Cloud Mitigation laser, vacuum, operation, multipactoring 1220
 
  • M. Sitko, V. Baglin, S. Calatroni, P. Chiggiato, B. Di Girolamo, E. Garcia-Tabares Valdivieso, M. Taborelli
    CERN, Geneva, Switzerland
  • A. Abdolvand, D. Bajek, S. Wackerow
    University of Dundee, Nethergate, Dundee, Scotland, United Kingdom
  • M. Colling, T.J. Jones, P.A. McIntosh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
 
  The LHC operation has proven that the electron cloud could be a significant limiting factor in machine performance, in particular for future High Luminosity LHC (HL-LHC) beams. Electron clouds, generated by electron multipacting in the beam pipes, leads to beam instabilities and beam-induced heat load in cryogenic systems. Laser Engineered Surface Structures (LESS) is a novel surface treatment which changes the morphology of the internal surfaces of vacuum chambers. The surface modification results in a reduced secondary electron yield (SEY) and, consequently, in the eradication of the electron multipacting. Low SEY values of the treated surfaces and flexibility in choosing the laser parameters make LESS a promising treatment for future accelerators. LESS can be applied both in new and existing accelerators owing to the possibility of automated in-situ treatment. This approach has been developed and optimised for the LHC beam screens in which the electron cloud has to be mitigated before the HL-LHC upgrade. We will present the latest steps towards the implementation of LESS.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUZGBE3  
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TUPMF005 Simulation of Inverse Compton Scattering and Its Implications on the Scattered Linewidth simulation, emittance, laser, scattering 1254
 
  • N. Ranjan, B. Terzić
    ODU, Norfolk, Virginia, USA
  • I. Drebot, L. Serafini
    Istituto Nazionale di Fisica Nucleare, Milano, Italy
  • G.A. Krafft
    JLab, Newport News, Virginia, USA
  • V. Petrillo
    Universita' degli Studi di Milano & INFN, Milano, Italy
 
  Funding: This paper is authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Compton scattering, though first described some one hundred years ago, has recently experienced a surge of interest due to the search for energy sources that are capable of yielding low emission bandwidths. In particular, the desire for hard x-rays with energies greater than 10 keV has led to increased study of inverse Compton sources. The rise in interest concerning inverse Compton sources has increased the need for efficient models that properly quantify the behavior of scattered radiation given a set of interaction parameters. The current, state-of-the-art, simulations rely of Monte Carlo-based methods, which may fail to properly model collisions of bunches in low-probability regions of the spectrum. Furthermore, the random sampling of the simulations may lead to inordinately high runtimes. Our methods can properly model behaviors exhibited by the collisions by integrating over the emissions of the electrons in the bunch in a lessened amount of time. Analytical simulations of Gaussian laser beams closely verify the behavior predicted by an analytically derived scaling law describing bandwidth of scattered radiation.
Current affiliation of primary author (Nalin Ranjan) is Princess Anne High, Virginia Beach, VA 23452, USA.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF005  
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TUPMF008 Design, Construction, and Magnetic Field Measurements of a Helical Superconducting Undulator for the Advanced Photon Source undulator, photon, storage-ring, experiment 1263
 
  • M. Kasa, S.J. Bettenhausen, J.D. Fuerst, E. Gluskin, Q.B. Hasse, Y. Ivanyushenkov, I. Kesgin, Y. Shiroyanagi, E. Trakhtenberg
    ANL, Argonne, Illinois, USA
 
  Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
A helical superconducting undulator (HSCU) was developed and installed at the Advanced Photon Source (APS). Implementation of a unique design of the helical coil former allowed for a compact turn around scheme of the conductor at the ends of the device during winding. Inherent to the coil winding design was the gradual reduction of the magnitude of the magnetic field at the ends of the device. The coil former design along with the magnetic measurement results will be described.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF008  
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TUPMF010 A Conceptual Design of a Compact Wakefield Accelerator for a High Repetition Rate Multi User X-ray Free-Electron Laser Facility wakefield, GUI, quadrupole, wiggler 1266
 
  • A. Zholents, D.S. Doran, W.G. Jansma, M. Kasa, R. Kustom, J.G. Power, N.O. Strelnikov, K.J. Suthar, E. Trakhtenberg, I. Vasserman, G.J. Waldschmidt, J.Z. Xu
    ANL, Argonne, Illinois, USA
  • S. Baturin
    Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA
  • H. Perez
    IIT, Chicago, Illinois, USA
 
  Funding: Supported by U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357
A preliminary design of a collinear wakefield accelerator is described. It is assumed that the array of such accelerators will play a central role in a free-electron laser-based x-ray user facility under consideration at Argonne National Laborator [1].
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF010  
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TUPMF020 Demonstration of Fast, Single-shot Photocathode QE Mapping Method Using MLA Pattern Beam laser, cathode, gun, optics 1293
 
  • E.E. Wisniewski, M.E. Conde, D.S. Doran, W. Gai, Q. Gao, W. Liu, J.G. Power, C. Whiteford
    ANL, Argonne, Illinois, USA
  • Q. Gao
    TUB, Beijing, People's Republic of China
  • G. Ha
    PAL, Pohang, Republic of Korea
  • A. Halavanau, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • P. Piot
    Fermilab, Batavia, Illinois, USA
 
  Funding: UChicago Argonne, LLC, Operator of Argonne National Laboratory ("Argonne"). Argonne, a U.S.A. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357.
Quantum efficiency (QE) is the chief figure of merit in the characterization of photocathodes. Semiconductor photocathodes, especially when used in high rep-rate photo-injectors, are known to show QE degradation over time and must be replaced. The total QE is the basic diagnostic which is used widely and is easy to obtain. However, a QE map indicating variations of QE across the cathode surface has greater utility. It can quickly diagnose problems of QE inhomogeneity. Most QE mapping techniques require hours to complete and are thus disruptive to a user facility schedule. A fast, single-shot method has been proposed (citation) using a micro-lens array (MLA) generated QE map. In this paper we report the implementation of the method at Argonne Wakefield Accelerator facility. A micro-lens array (MLA) is used to project an array of beamlets onto the photocathode. The resulting photoelectron beam in the form of an array of electron beamlets is imaged at a YAG screen. Four synchronized measurements are made and the results used to produce a QE map of the photocathode.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF020  
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TUPMF022 Electron Beam Scanning in the Delta-Type Undulators for Sirius undulator, radiation, polarization, storage-ring 1300
 
  • A. B. da Cruz, L. Liu
    LNLS, Campinas, Brazil
 
  We report on simulation studies to analyze the possibility of scanning the electron beam, and not scanning the sample, in CDI experiments using a Delta-Type undulator in the 3GeV Sirius electron storage ring presently under construction at LNLS. This would allow much faster scans in diffraction limited storage rings such as Sirius. We study displaced beam trajectories through the undulators and analyze the effects on the emitted radiation. It is possible to show that displacements on the order of ± 500 micrometers around the center will introduce variations in the radiation spectrum that are less that 1 per cent and thus acceptable for Coherent Diffraction Imaging experiments.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF022  
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TUPMF025 LEReC Photocathode DC Gun Beam Test Results gun, cathode, operation, laser 1306
 
  • D. Kayran, Z. Altinbas, D. Bruno, M.R. Costanzo, A.V. Fedotov, D.M. Gassner, X. Gu, L.R. Hammons, P. Inacker, J.P. Jamilkowski, J. Kewisch, C.J. Liaw, C. Liu, K. Mernick, T.A. Miller, M.G. Minty, V. Ptitsyn, T. Rao, J. Sandberg, S. Seletskiy, P. Thieberger, J.E. Tuozzolo, E. Wang, Z. Zhao
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Low Energy RHIC Electron cooler (LEReC) project is presently under commissioning at Brookhaven National Laboratory (BNL). LEReC requires high average current up to 85mA and high-quality electron beam. A 400 kV DC gun equipped with a photocathode and laser system has been chosen to provide a source of high-quality electron beams. We started testing the DC gun during the RHIC run 2017. First electron beam from LEReC DC gun was delivered in April 2017 *. During the DC gun test critical elements of LEReC such as laser beam system, cathode exchange system, cathode QE lifetime, DC gun stability, beam instrumentation, the high-power beam dump system, machine protection system and controls have been tested. Average current of 10 mA for few hours of operation was reached in August 2017. In this paper we present experimental results and experience learned during the LEReC DC gun beam testing.
* D. Kayran et al., "First Results of Commissioning DC Photo-gun for RHIC Low Energy Electron Cooler (LEReC)", in Proc of ERL2017.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF025  
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TUPMF027 Impedance Modeling for eRHIC impedance, vacuum, dipole, quadrupole 1309
 
  • A. Blednykh, G. Bassi, M. Blaskiewicz, C. Hetzel, V. Ptitsyn, V.V. Smaluk, F.J. Willeke
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by the US DOE under contract number DE-SC0012704
The impedance budget for the eRHIC project is discussed at its earlier stage of development. As a first step, with the eRHIC lattice and beam parameters , we use the geometric impedances of the vacuum chamber components simulated for the NSLS-II project. The impedance budged will be updated next with more impedance data simulated for the optimized eRHIC vacuum components. It will allows us to keep track on the collective effects changes with more realistic components added to the ring.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF027  
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TUPMF032 RF Conceptual Design of Normal Conducting Cavity for an eRHIC Rapid Cycling Synchrotron cavity, GUI, coupling, vacuum 1316
 
  • B. P. Xiao, M. Blaskiewicz, J.M. Brennan, D. Holmes, K.S. Smith, T. Xin, A. Zaltsman
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE.
The Rapid Cycling Synchrotron (RCS) for the eRHIC Ring-Ring design will provide on energy injection (up to 18 GeV) of high charge, polarized electron bunches to the eRHIC electron storage ring. The RF system comprises a large number of 563MHz fundamental cavities, providing up to 45MV per turn. The cavities will operate in pulsed mode with <20% duty factor, at a repetition rate of 1 Hz. In this paper we report the conceptual RF design of the cavity.
 
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TUPMF038 Design Considerations for an Ultralow Emittance Storage Ring for the Canadian Light Source emittance, sextupole, lattice, quadrupole 1334
 
  • L.O. Dallin
    CLS, Saskatoon, Saskatchewan, Canada
 
  Demands from light source scientists for more brilliant xray beams have resulted in the emergence of 4th generation storage rings. These demands include photon beams that are highly focussed and beams with high transverse coherence. Both these requirements are achieved with ultralow electron beam emittance. The practical development of the multi-bend achromat (MBA) concept by MAX IV has spurred many synchrotron light sources around the world to develop similar machines. For existing facilities two options are available: upgrading existing machines or building a new structure. The Canadian Light Source (CLS) has explored both options and has determined a new storage ring is required. Several design options for a 3.0 GeV ring have been developed. Best results are achieved when tracking is used to optimize the phase advance through the MBA structure to reduce the impact of the sextupoles on the dynamic aperture. Structures where no geometric sextupoles are required have been achieved while producing ultralow emittances.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF038  
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TUPMF040 Alignment of Current Strips at the Canadian Light Source alignment, closed-orbit, undulator, vacuum 1342
 
  • W.A. Wurtz
    CLS, Saskatoon, Saskatchewan, Canada
  • Q.L. Zhang
    SINAP, Shanghai, People's Republic of China
 
  The Quantum Materials Spectroscopy Centre beamline at the Canadian Light Source will employ a 180 mm period elliptically polarizing undulator (EPU180), which will have significant impacts on beam dynamics with large tune shifts and reductions in dynamic aperture. Current strips mounted to the vacuum chamber are intended to mitigate the effects of EPU180 with each strip powered by an independent power supply. It is important to accurately model the current strips in order to calculate the required compensation. We model the current strips as straight wires, parallel to the electron beam, with small horizontal and vertical displacements from their nominal positions. As the real current strips are not completely straight, this is an effective model, but justified as we are mostly interested in the magnetic field integrated along the strips. By activating two strips and measuring the ratio of the two currents needed to minimize closed orbit distortion in the horizontal and vertical planes, we can find the effective horizontal and vertical displacements of the straight wires in the model. Our goal is to create an effective model of the strips from beam-based measurements.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF040  
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TUPMF042 Design of a High Dose Rate Micro-Focused X-Ray Source target, emittance, dipole, cavity 1346
 
  • X. He, S.Q. Liao, J. Long, J. Shi, W. Wang, L. Yang
    CAEP/IFP, Mainyang, Sichuan, People's Republic of China
 
  High energy X-ray computer tomography has wide application in industry, especially in quality control of complicated high-tech equipment. In many applications, higher spatial resolution is needed to discover smaller defects. Decreasing the spot size of the X-Ray source is a promising way to get higher spatial resolution. Rhodotron have been used to produce high power CW electron beam in hundreds of kilowatts level. In this paper, we propose to use an improved Rhodotron to generate high brightness electron beam with high average power. Beam dynamics study shows that when producing tens of kilowatts electron beam, the normalized RMS emittance can be lower than 10 μm, and the relative RMS energy spread can be lower than 0.2%. The beam can be focused to a spot size of about 100μm by using a series of quadruple, and converted to X-Ray by using a rotating target within several kilowatts beam power. Improved Rhodotron proposed in this paper is a good candidate of X-ray source for high resolution high energy industrial CT systems.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF042  
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TUPMF044 First Lasing of the CAEP THz FEL Facility Driven by a Superconducting Accelerator FEL, laser, free-electron-laser, undulator 1349
 
  • D. Wu, W. Bai, D.R. Deng, C.L. Lao, M. Li, S.F. Lin, X. Luo, L.J. Shan, X. Shen, H. Wang, J. Wang, Y. Xu, L.G. Yan, X. Yang, K. Zhou
    CAEP/IAE, Mianyang, Sichuan, People's Republic of China
  • Y.H. Dou, X.J. Shu
    Institute of Applied Physics and Computational Mathematics, People's Republic of China
  • W.-H. Huang
    TUB, Beijing, People's Republic of China
  • X.Y. Lu
    PKU, Beijing, People's Republic of China
 
  Funding: Work supported by China National Key Scientific Instrument and Equipment Development Project (2011YQ130018), National Natural Science Foundation of China (11475159, 11505173, 11575264 and 11605190)
The stimulated saturation of the terahertz free electron laser at China Academy of Engineering Physics was reached in August, 2017. This THz FEL facility consists of a GaAs photocathode high-voltage DC gun, a superconducting RF linac, a planar undulator and a quasi-concentric optical resonator. The terahertz wave frequency is continuous adjustable from 2 THz to 3 THz. The average power is more than 10 W and the micro-pulse power is more than 0.3 MW.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF044  
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TUPMF045 Performance Optimization of a Prototype Undulator U38 Using Multi-Objective Genetic Algorithm undulator, MMI, laser, free-electron-laser 1353
 
  • L.G. Yan, D.R. Deng, P. Li, D. Wu
    CAEP/IAE, Mianyang, Sichuan, People's Republic of China
 
  Funding: The project of the national large-scale instrument development: 2011YQ130018; National Natural Science Foundation of China: 11505174, 11505173 and 11605190.
Genetic Algorithm (GA) is one of the most excellent method to search the optimal solution of a problem, which has been applied to solve various problems. It is hard to estimate shim applied on raw undulator precisely. There are many methods have been developed to solve the problem. In this proceeding, we measured the magnetic field distribution of prototype undulator U38 and concluded the shim using multi-objective GA. The code was written with the language of Python and based on the package pyevolve. A multi-objective fitness function was setup to implement the multi-objective optimization. Experimentally,performances satisfied the requirements by shimming U38 three times. The trajectory center deviation, peak-to-peak error and phase error are reduced to 0.15 mm, 0.49% and 1°.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF045  
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TUPMF051 Generating Ultrashort X-Ray Pulse in a Diffraction-Limed Storage Ring by Phase-Merging Enhanced Harmonic Generation with Normal Modulator bunching, radiation, laser, undulator 1371
 
  • W. Liu, Y. Jiao
    IHEP, Beijing, People's Republic of China
 
  In recent years, the study of ultrafast processes has increased the demand for ultrashort pulses. The duration of the synchrotron radiation pulse is generally in the range of 10-100 ps, which cannot be used in the experiments of studying the ultrafast process. Thus it is interesting to explore a way of obtaining sub-picosecond radiation pulses in storage ring light sources. The phase-merging enhanced harmonic generation (PEHG) scheme using a transverse gradient undulator as the modulator can be used to generate coherent radiation at high harmonic, which is very suitable for the generating ultrashort pulses in a diffraction-limed storage ring (DLSR). This paper presents a new PEHG modulation scheme, using a normal undulator as the modulator. This scheme is technically easier to be realized in a DLSR. Simulation is performed to demonstrate the effectiveness of this method.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF051  
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TUPMF055 Phase Matching Application in Hard X-Ray Region of HEPS undulator, brilliance, radiation, photon 1386
 
  • X.Y. Li, Z. Duan, Y. Jiao, S.K. Tian
    IHEP, Beijing, People's Republic of China
 
  For the 6 meters long straight-section of HEPS, a double collinear double-cryogenic permanent magnet undulator(CPMU) structure is designed for high energy photon users to achieve higher brightness. Angular profiles of radiation produced by the double undulator configuration has been derived analytically. The efficiency of phase shifter on improving the brightness of double-CPMU is therefore evaluated with the beam energy spread is taken into account.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF055  
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TUPMF061 Physical Design of the 500 MeV Electron Linac for the High Energy Photon Source linac, gun, bunching, emittance 1404
 
  • S. Pei, D.Y. He, X. He, J.L. Li, J. Liu, X. Ma, C. Meng, X. Wang, O. Xiao, J.R. Zhang, Z.S. Zhou
    IHEP, Beijing, People's Republic of China
  • S. Shu
    Institute of High Energy Physics (IHEP), Chinese Academy of Sciences, Beijing, People's Republic of China
 
  Funding: Work supported by the HEPS project and the National Natural Science Foundation of China (11475201). peisl@ihep.ac.cn
The High Energy Photon Source (HEPS) is a 6 GeV light source with ultra-low emittance, it is proposed to be built at Huairou district, northeast suburb of Beijing, China. A 500 MeV electron linac will be used to generate the electron beam for injection into the booster. Here the preliminary physical design of the electron linac is presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF061  
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TUPMF065 The Role of Electron-Phonon Scattering in Transverse Momentum Conservation in PbTe(111) Photocathodes experiment, scattering, photon, cathode 1414
 
  • J. K. Nangoi, T.A. Arias
    Cornell University, Ithaca, New York, USA
  • S.S. Karkare, H.A. Padmore
    LBNL, Berkeley, California, USA
  • W.A. Schroeder
    UIC, Chicago, Illinois, USA
 
  Funding: The U.S. National Science Foundation under Award PHY-1549132, the Center for Bright Beams.
The state of the art in creating high quality electron beams for particle accelerator applications and next generation ultrafast electron diffraction and microscopy involves laser-generated photoemission. A high quality beam requires that electrons emerge from the surface with low mean transverse energy (MTE). Recent density-functional theory calculations by T. Li and W. A. S. [arXiv:1704.00194v1 [physics.acc-ph] (2017)] suggest that PbTe(111) will produce low-MTE photoelectrons due to the low effective electron mass associated with its electronic band structure. Based on this, we measured the distribution of photoelectrons from PbTe(111) and found the MTE to be about 20x larger than expected. To explain the apparent lack of transverse momentum conservation, we carried out many-body photoemission calculations including electron-phonon scattering. Our results are in far better agreement with the experiment, underscoring the importance of electron-phonon scattering in photoemission from PbTe(111), and suggest that cooling could mitigate the phonon effects on the MTE for this material.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF065  
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TUPMF069 Low Gain FEL Oscillator Option for PETRA IV FEL, undulator, emittance, storage-ring 1420
 
  • I.V. Agapov
    DESY, Hamburg, Germany
  • Y.-C. Chae
    ANL, Argonne, Illinois, USA
  • W. Hillert
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
 
  Next generation synchrotron storage rings will have electron beam density approaching that necessary for driving an XFEL. It falls short of the quality required for the high-gain x-ray regime above 1 keV, mainly due to the large energy spread and small peak current, bit is sufficient to reach low-gain regime. Here we explore the parameter space of a low gain XFEL oscillator, to establish the feasibility range of such a device for the Petra upgrade project.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF069  
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TUPMF076 Temporal X-ray Reconstruction Using Temporal and Spectral Measurements simulation, photon, FEL, laser 1440
 
  • F. Christie, J. Rönsch-Schulenburg, M. Vogt
    DESY, Hamburg, Germany
  • Y. Ding, Z. Huang, J. Krzywinski, A.A. Lutman, T.J. Maxwell, D.F. Ratner
    SLAC, Menlo Park, California, USA
  • V. A. Jhalani
    CALTECH, Pasadena, California, USA
 
  Transverse deflecting structures (TDS) are widely used in accelerator physics to measure the longitudinal density of particle bunches. When used in combination with a dispersive section, the whole longitudinal phase space density can be imaged. At the Linac Coherent Light Source (LCLS), the installation of such a device downstream of the undulators enables the reconstruction of the X-ray temporal intensity profile by comparing longitudinal phase space distributions with lasing on and lasing off*. However, the resolution of this TDS is limited to around 1 fs rms (root mean square), and therefore, in most cases, it is not possible to resolve single self-amplified spontaneous emission (SASE) spikes within one photon pulse. By combining the intensity spectrum from a high resolution photon spectrometer** and the temporal structure from the TDS, the overall resolution is enhanced, thus allowing the observation of temporal, single SASE spikes. The combined data from the spectrometer and the TDS is analyzed using an iterative algorithm to obtain the actual intensity profile. In this paper, we present the reconstruction algorithm as well as analyzed data obtained from simulations which shows the reliability of this method. Real data will be published at a later stage.
*Y. Ding et al., Phys. Rev. ST AB, 14, 120701, 2011.
**D. Zhu et al., Appl. Phys. Lett., 101, 034103, 2012.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF076  
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TUPMF078 Control of FEL Radiation Properties by Tailoring the Seed Pulses FEL, laser, experiment, simulation 1444
 
  • V. Grattoni, R.W. Aßmann, J. Bödewadt, I. Hartl, C. Lechner, B. Manschwetus, M.M. Mohammad Kazemi
    DESY, Hamburg, Germany
  • A. Azima, W. Hillert, V. Miltchev, J. Roßbach
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • S. Khan, T. Plath
    DELTA, Dortmund, Germany
 
  Seeded free-electron lasers (FELs) produce intense, ultrashort and fully coherent X-ray pulses. These seeded FEL pulses depend on the initial seed properties. Therefore, controlling the seed laser allows tailoring the FEL radiation for phase-sensitive experiments. In this contribution, we present detailed simulation studies to characterize the FEL process and to predict the operation performance of seeded pulses. In addition, we show experimental data on the temporal characterization of the seeded FEL pulses performed at the sFLASH experiment in Hamburg.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF078  
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TUPMF079 An Option to Generate Seeded FEL Radiation for FLASH1 FEL, laser, undulator, radiation 1448
 
  • V. Grattoni, R.W. Aßmann, J. Bödewadt, I. Hartl, C. Lechner, B. Manschwetus, M.M. Mohammad Kazemi
    DESY, Hamburg, Germany
  • W. Hillert, V. Miltchev, J. Roßbach
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • S. Khan, T. Plath
    DELTA, Dortmund, Germany
 
  The FLASH free-electron laser (FEL) at DESY is currently operated in self-amplified spontaneous emission (SASE) mode in both beamlines FLASH1 and FLASH2. Seeding offers unique properties for the FEL pulse, such as full coherence, spectral and temporal stability. In this contribution, possible ways to carry the seeded FEL radiation to the user hall are presented with analytical considerations and simulations. For this, components of the sFLASH seeding experiment are used.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF079  
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TUPMF084 Optimization of the Injection Kicker Bump Leakage at PETRA III kicker, injection, septum, feedback 1467
 
  • J. Keil, G. Kube, F. Obier, G.K. Sahoo, R. Wanzenberg
    DESY, Hamburg, Germany
 
  PETRA III is a third generation synchrotron light source at DESY delivering high brightness photon beams for users at 21 beam lines. It is operated at 6 GeV with a beam current of 100 mA in top-up mode and is in operation for users since 2010. An off-axis injection scheme is used to accumulate beam from the booster synchrotron DESY II in PETRA III. Three fast injection kicker magnets generate a closed orbit bump for one turn to move the stored beam near to the injection septum magnet. Ideally the orbit bump generated by the 10 μs long half-sine pulses of the kickers should be closed. Due to differences in pulse shape as well as timing and amplitude errors of the pulses there is some leakage of the injection bump which disturbs the closed orbit and affects the beam quality during top-up operation. Turn-by-turn data from the beam position monitor (BPM) system of PETRA III have been used to measure the bump leakage for different bucket positions in the filling pattern. The procedure to reduce the injection kicker bump leakage and the achieved improvement will be discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF084  
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TUPMF085 Status of the sFLASH Experiment FEL, laser, photon, experiment 1471
 
  • C. Lechner, R.W. Aßmann, J. Bödewadt, V. Grattoni, I. Hartl, T. Laarmann, M.M. Mohammad Kazemi, A. Przystawik
    DESY, Hamburg, Germany
  • A. Azima, H.B. Biss, M. Drescher, W. Hillert, L.L. Lazzarino, V. Miltchev, J. Roßbach
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • S. Khan, T. Plath
    DELTA, Dortmund, Germany
 
  Funding: This work is supported by the Federal Ministry of Education and Research of Germany within FSP-302 under FKZ 05K13GU4, 05K13PE3, and 05K16PEA.
The sFLASH experiment at the free-electron laser (FEL) FLASH1 is a setup for the investigation of external FEL seeding. Since 2015, the seeding scheme high-gain harmonic generation (HGHG) is being studied. At the end of the seeded FEL, an RF deflector enables time-resolved analysis of the seeded electron bunches while the photon pulses can be characterized using the technique of THz streaking. In this contribution, we present the current configuration of the experiment and give an overview of recent experimental results.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF085  
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TUPMF086 Status of the ARES RF Gun at SINBAD: From its Characterization and Installation towards Commissioning gun, cavity, linac, status 1474
 
  • B. Marchetti, R.W. Aßmann, S. Baark, F. Burkart, U. Dorda, K. Flöttmann, I. Hartl, J. Hauser, J. Herrmann, M. Hüning, K. Knebel, O. Krebs, G. Kube, W. Kuropka, S. Lederer, F. Lemery, F. Ludwig, D. Marx, F. Mayet, M. Pelzer, I. Peperkorn, F. Poblotzki, S. Pumpe, J. Rothenburg, H. Schlarb, M. Titberidze, G. Vashchenko, T. Vinatier, P.A. Walker, L. Winkelmann, K. Wittenburg, S. Yamin, J. Zhu
    DESY, Hamburg, Germany
 
  The SINBAD facility (Short and INnovative Bunches and Accelerators at DESY) is foreseen to host multiple experiments relating to the production of ultra-short electron bunches and novel high gradient acceleration techniques. The SINBAD-ARES linac will be a conventional S-band linear RF accelerator allowing the production of low charge (0.5 pC - tens pC) ultra-short electron bunches (FWHM length =< 1 fs - few fs) with 100 MeV energy. The installation of the linac will proceed in stages. In this paper we report on the status of the characterization of the ARES RF gun and the installations of the related infrastructure.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF086  
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TUPMF089 Possible Upgrades of FLASH –- A View from the Accelerator-Perspective undulator, laser, FEL, optics 1477
 
  • M. Vogt, B. Faatz, K. Honkavaara, J. Rönsch-Schulenburg, S. Schreiber, J. Zemella
    DESY, Hamburg, Germany
 
  Recently FLASH (Free electron LASer in Hamburg) at DESY has been granted funding for a refurbishment project covering among others the replacement of two old SRF modules, an upgrade of the injector lasers and an upgrade of parts of the electron beam diagnostics. In addition we are proposing several possible upgrades and new features for the injector and the drive linac as well as in the undulator beamlines. Here we present options which are in our opinion technically feasible and at the same time operationally manageable.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF089  
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TUPMF090 Status of the Superconducting Soft X-Ray Free-Electron Laser FLASH at DESY FEL, laser, operation, undulator 1481
 
  • M. Vogt, K. Honkavaara, M. Kuhlmann, J. Rönsch-Schulenburg, S. Schreiber, R. Treusch
    DESY, Hamburg, Germany
 
  FLASH, the free-electron laser (FEL) user facility at DESY, has delivered high brilliance VUV and soft x-ray FEL radiation for photon experiments since summer 2005. In 2014 and 2015 a second beamline, FLASH2, has been commissioned in parallel to user operation at FLASH1. FLASH's superconducting linac can produce bunch trains of up to 800 bunches within a 0.8 ms RF flat top at a repetition rate of 10 Hz. In standard operation during 2017 FLASH supplied up to 500 bunches in two bunch trains with independent fill patterns and compression schemes. Since mid 2017 initial commissioning of a third experimental beamline, accommodating the FLASHForward plasma wakefield acceleration experiment, has started. We report on the highlights of the FLASH operation in 2017/2018.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF090  
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TUPMK004 Using Decoherence to Prevent Damage to the Swap-Out Dump for the APS Upgrade simulation, emittance, kicker, storage-ring 1494
 
  • M. Borland, J.C. Dooling, R.R. Lindberg, V. Sajaev, A. Xiao
    ANL, Argonne, Illinois, USA
 
  Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The Advanced Photon Source (APS) is pursuing an upgrade of the storage ring to a hybrid seven-bend-achromat* design, which will operate in swap-out mode. The ultra-low emittance (about 30 pm in both planes) combined with the desire to provide high charge (15 nC) in individual bunches, entails very high energy density in the beam. Simple estimates, confirmed by simulation, indicate that interaction of such a bunch with the dump material will result in localized melting. Over time, it is possible that the beam would drill through the dump and vent the ring vacuum. This would seem to prevent extraction and dumping of bunches as part of swap out, and also suggests that transferring of bunches out of the ring carries significant risk. We devised an idea for using a pre-kicker to cause decoherence of the target bunch emittances, making it safe to extract. Simulations show that the concept works very well.
*L. Farvacque et al., IPAC13, 79 (2013).
 
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TUPMK006 Sub-fs Electron Bunch Generation Using Emittance Exchange Compressor emittance, simulation, sextupole, cavity 1501
 
  • J.M. Seok, M. Chung
    UNIST, Ulsan, Republic of Korea
  • M.E. Conde, J.G. Power
    ANL, Argonne, Illinois, USA
  • G. Ha
    PAL, Pohang, Republic of Korea
 
  Sub-fs electron bunch has been pursued in the last decade using several different methods. These methods rely on one of the velocity difference or path length difference to compress a long bunch to sub-fs bunch. Here, we introduce a new method to generate the compression. Emittance Exchange (EEX) beamline makes transverse-to-longitudinal exchange of phase space. In this beamline, a transverse focusing at the upstream introduces a longitudinal compression at the downstream due to the exchange. Since this exchange scheme does not rely on the velocity or the path length differences, it does not require any longitudinal manipulation (e.g. chirp), and it could generate a short bunch with well-controlled nonlinear effects using nonlinear magnets. We present preliminary simulation results of EEX based bunch compression and sub-fs bunch generation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMK006  
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TUPMK008 Highly-stable, High-power Picosecond Laser Optically Synchronized to a UV Photocathode Laser for an ICS Hard X-ray Generation laser, timing, cathode, linac 1504
 
  • K.-H. Hong
    MIT, Cambridge, Massachusetts, USA
  • D. Gadonas, L.M. Hand, K. Neimontas, A. Senin, V. Sinkevicius
    Light Conversion, Vilnius, Lithuania
  • W.S. Graves, M.R. Holl, L.E. Malin, C. Zhang
    Arizona State University, Tempe, USA
  • S. Klingebiel, T. Metzger, K. Michel
    TRUMPF Scientific Lasers GmbH + Co. KG, Munchen-Unterfoehring, Germany
 
  Under the CXLS project at Arizona State University we are developing an inverse Compton scattering (ICS) hard X-ray source* towards a compact XFEL with electron nano-bunching. The ICS interaction is critically dependent on the quality of driver pulses such as: 1) available peak intensity, 2) energy/pointing stability, and 3) relative timing stability to UV pulses initially triggering electron beams. Here, we report on a highly stable, 1 kHz, 200 mJ, 1.1 ps, 1030 nm laser with good beam quality as an ICS driver, optically synchronized to a UV photocathode laser. The ICS driver is based on a Yb:YAG thin-disk regenerative amplifier (RGA), ensuring an excellent energy stability (shot-to-shot 0.52% rms; 0.14% rms over 24 hours). The pointing stability better than 4 urad is obtained. The M2 factor is as good as ~1.5 at the full energy, leading to the achievable laser intensity of >1017 W/cm2 with f/10 focusing. The photocathode laser, a frequency-quadrupled Yb:KGW RGA, share a common seed oscillator with the ICS driver for optical synchronization. The residual sub-ps timing drift is further reduced to 33 fs rms using an optical locking scheme based on a parametric amplifier.
* W.S. Graves et al., "Compact X-ray source based on burst mode inverse compton scattering at 100 kHz," Phys. Rev. ST Accel. Beams, Vol. 17, p. 120701 (Dec. 2014).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMK008  
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TUPMK009 Electron Beam Optics for the ASU Compact XFEL dipole, FEL, simulation, laser 1507
 
  • C. Zhang, W.S. Graves, M.R. Holl, L.E. Malin
    Arizona State University, Tempe, USA
  • E.A. Nanni
    SLAC, Menlo Park, California, USA
 
  Funding: National Science Foundation Division of Physics (Accelerator Science) award 1632780, award 1231306. DOE grant DE-AC02-76SF00515.
Arizona State University (ASU) is pursuing a new concept for a compact x-ray FEL (CXFEL) as a next phase of compact x-ray light source (CXLS). We describe the electron beam optics design for the ASU compact XFEL. In previous experiments we introduced a grating diffraction method to generate a spatially modulated beam. We plan to combine a telescope imaging system with emittance exchange (EEX) to magnify/demagnify the modulated beam and transfer it from transverse modulation into a longitudinal one to make it an ideal seed for phase-coherent XFEL. The simulation results of the beam line setup will be demonstrated. Our first goal is to successfully image the modulated beam with desired magnification then we will investigate various magnification and magnets combinations and optimize aberration correction.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMK009  
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TUPMK012 Acceleration of Charged Particles by Own Field in a Non-Stationary One-Dimensional Stream interface, ECR, acceleration, operation 1516
 
  • A.S. Chikhachev
    Allrussian Electrotechnical Institute, Moskow, Russia
 
  The behavior of a non-stationary stream of the charged particles interacting with own field is studied. For the description the integral of the movement received in works * ** - Meshchersky's integral is used. The additional integral of the movement - interfaced to Meshchersky's integral, necessary for completely self-agreed description of a stream of the particles interacting with own field is constructed. The system of the equations reducing a problem to the solution of system of the ordinary differential equations is removed. Private decisions for potential, density of particles and density of current are provided. Earlier the problem was studied in work ***.
* Mestschersky J. Astronomische Nachrichten, 1893, T.132, N3153, p. 9.
** Nestschersky ibid, 1902, T.159, N3807, p. 15.
*** Chikhachev A.S., Technical Phisics, 2014, vol 59, N 4, pp 487-493.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMK012  
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TUPML004 Correction of Emittance Growth Due to Quad Components in Solenoids With Quad Correctors at AWA emittance, solenoid, simulation, linac 1536
 
  • L.M. Zheng, C.-X. Tang
    TUB, Beijing, People's Republic of China
  • M.E. Conde, D.S. Doran, W. Gai, W. Liu, J.G. Power, J.H. Shao, C. Whiteford, E.E. Wisniewski
    ANL, Argonne, Illinois, USA
 
  An asymmetrical electron beam is observed on the drive beamline at Argonne Wakefield Accelerator (AWA) due to the quad components in the solenoids. An ASTRA simulation shows that the emittance will increase when the electron beam passes through solenoids with quad errors. We use two quad correctors to correct this emittance growth. A preliminary emittance correction result is presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML004  
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TUPML006 Updates of the Argonne Cathode Test-stand cathode, laser, gun, experiment 1542
 
  • J.H. Shao, M.E. Conde, D.S. Doran, W. Gai, W. Liu, J.F. Power, C. Whiteford, E.E. Wisniewski, L.M. Zheng
    ANL, Argonne, Illinois, USA
  • S.P. Antipov, G. Chen, E. Gomez, C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • S.V. Baryshev
    Michigan State University, East Lansing, Michigan, USA
 
  The Argonne Cathode Test-stand (ACT) is a unique testbed to develop cathodes and to conduct fundamental surface study under ultra-high rf field (up to 700 MV/m with pin-shaped cathodes). The test-stand consists of an L-band 1.3 GHz single-cell photocathode rf gun and a field emission (FE) imaging system to locate emitters with a resolution of ∼20 𝜇m. In the recent upgrade, UV laser has been introduced to improve the imaging system and to significantly expand the ACT towards photoemission and laser-assisted field emission research. In addition, a load-lock system has been added to the beam line to expedite the cathode switching period. The paper will present details of the upgrade as well as experiments planned in the near future.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML006  
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TUPML009 Design and Test Plan for a Prototype Corrugated Waveguide GUI, wakefield, experiment, simulation 1550
 
  • G.J. Waldschmidt, D.S. Doran, G. Ha, R. Kustom, A. Nassiri, J.G. Power, A. Zholents
    ANL, Argonne, Illinois, USA
  • A.E. Siy
    UW-Madison/PD, Madison, Wisconsin, USA
 
  A cylindrical, corrugated wakefield accelerating structure with a 1 mm radius bore is being designed to facilitate sub-terahertz Čerenkov radiation produced by an elec-tron bunch propagating along the waveguide. A 220 GHz axial mode for the wakefield is being considered. The waveguide is being optimized to maximize the trailing wakefield potential while maintaining a ratio of the trail-ing potential to the peak decelerating voltage in the bunch, or transformer ratio, of approximately 5 for the door step peak current distribution [1]. In order to evalu-ate the manufacturing tolerances and perform rf and electron beam testing of the waveguide, a 21 GHz proto-type waveguide structure will be built consisting of re-configurable parts allowing modelling of various fabrica-tion errors. Measurements with an electron beam will be performed at the Argonne Wakefield Accelerator (AWA) test facility. Analysis of the experimental layout has been performed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML009  
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TUPML011 Experiments Producing Nanopatterned Electron Beams FEL, bunching, experiment, emittance 1553
 
  • L.E. Malin, W.S. Graves, J. Spence, K. Weiss, C. Zhang
    Arizona State University, Tempe, USA
  • R.K. Li, E.A. Nanni, X. Shen, S.P. Weathersby, J. Yang
    SLAC, Menlo Park, California, USA
 
  Funding: Work supported by NSF awards 1632780 and 1231306, DOE award DE-AC02-76SF00515, and the SLAC UED/UEM Initiative Program Development Fund.
RF photoinjectors are increasingly used to image at the nanoscale in much the same way as a Transmission Electron Microscope (TEM), which are generally sub-MeV energy. We have conducted electron diffraction experiments through a thin membrane of single crystal silicon using both the TEM and photoinjector, and have been able to model and predict the diffraction patterns using the multislice method. A nanopatterned single crystal silicon grating was also imaged in the TEM in the bright field, where all but the direct beam of the diffraction pattern is blocked, giving high contrast spatial modulations corresponding to the 400 nm pitch grating lithographically etched into the silicon. Drawing from our previous multislice calculations, we determined the crystallographic orientation that maximized the contrast in this spatial modulation at the energy of the TEM, giving a bunching factor comparable to a saturated FEL. We report on these key steps toward control of radiation phase and temporal coherence in an FEL.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML011  
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TUPML015 Influence of Ionization and Beam Quality on Interaction of Tw-Peak Co2 Laser With Hydrogen Plasma laser, plasma, simulation, experiment 1560
 
  • P. Kumar, V. Samulyak
    SBU, Stony Brook, USA
  • V. Samulyak, K. Yu
    BNL, Upton, Long Island, New York, USA
 
  3D numerical simulations of the interaction of a powerful CO2 laser with hydrogen jets demonstrating the role of ionization and laser beam quality are presented. Simulations are performed in support of the plasma wakefield accelerator experiments being conducted at the BNL Accelerator Test Facility (ATF). The CO2 laser at BNL ATF has several potential advantages for laser wakefield acceleration compared to widely used solid-state lasers. SPACE, a parallel relativistic Particle-in-Cell code, developed at SBU and BNL, has been used in these studies. A novelty of the code is its set of efficient atomic physics algorithms that compute ionization and recombination rates on the grid and transfer them to particles. The primary goal of the initial BNL experiments was to characterize the plasma density by measuring the sidebands in the spectrum of the probe laser. Simulations, that resolve hydrogen ionization and laser spectra, help explain several trends that were observed in the experiments.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML015  
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TUPML019 Design of Multi-Alkali Photocathode Preparation System for CTFEL Facility cathode, FEL, vacuum, laser 1571
 
  • D.X. Xiao, M. Li, Q. Pan, H. Wang, X. Yang
    CAEP/IAE, Mianyang, Sichuan, People's Republic of China
 
  The first saturated lasing of the China Academy of Engineering Physics tera-hertz free electron laser (CTFEL) facility has been realized. In order to improve the performance of the CTFEL facility, the multi-alkali photocathode with much longer life-time has been proposed to replace the GaAs photocathode currently used. This paper presents the design of the multi-alkali photocathode preparation system, which consists of three chambers: the suitcase chamber, the preparation chamber, and the loading chamber. The function of each chamber is also discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML019  
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TUPML021 A Beamline Design to Transport Laser Wakefield Electrons to a Transverse Gradient Undulator laser, undulator, quadrupole, plasma 1577
 
  • K.A. Dewhurst, H.L. Owen
    UMAN, Manchester, United Kingdom
  • E. Brunetti, D.A. Jaroszynski, S.M. Wiggins
    USTRAT/SUPA, Glasgow, United Kingdom
  • B.D. Muratori
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • B.D. Muratori
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
 
  Funding: This work was supported by the UK Science and Technology Facilities Council, Grant No. ST/G008248/1.
The Cockcroft Beamline is to be installed at the Scottish Centre for the Application of Plasma-based Accelerators (SCAPA). The beamline is designed to transport 1 GeV electrons from a laser wakefield acceleration (LWFA) source to a pair of transverse gradient undulators. The project aims to produce X-ray undulator radiation in the first phase and free-electron laser (FEL) radiation in the second phase. The total beamline will be less than 23 m long, thus the Cockcroft Beamline has the potential to be the UK's first compact X-ray FEL. Here we present the main features of the beamline design.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML021  
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TUPML022 Assessment of Transverse Instabilities in Proton Driven Hollow Plasma Wakefield Acceleration plasma, proton, wakefield, focusing 1581
 
  • Y. M. Li, G.X. Xia, Y. Zhao
    UMAN, Manchester, United Kingdom
  • S.J. Gessner
    CERN, Geneva, Switzerland
 
  Hollow plasma has been introduced into the proton-driven plasma wakefield accelerators to overcome the issue of beam quality degradation caused by the nonlinear transverse wakefields varying in radius and time in uniform plasma. It has been demonstrated in simulations that the electrons can be accelerated to energy frontier with well-preserved beam quality in a long hollow plasma channel. However, this scheme imposes tight requirements on the beam-channel alignment. Otherwise asymmetric transverse wakefields along the axis are induced, which could distort the driving bunch and deteriorate the witness beam quality. In this paper, by means of the 2D cartesian particle-in-cell simulations, we examine the potentially detrimental effects induced by the driving beam-channel offset and initial driver tilt, and then propose and assess the solutions to these driver inaccuracy issues.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML022  
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TUPML025 Long Lifetime Spin-Polarized GaAs Photocathode Activated by Cs2Te cathode, polarization, vacuum, photon 1589
 
  • J. Bae, L. Cultrera, P. Digiacomo
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • I.V. Bazarov
    Cornell University, Ithaca, New York, USA
 
  Funding: This work was supported by the Department of Energy Grant Nos. DE-SC0016203 and NSF PHY-1461111.
High intensity and highly spin-polarized electron source is of great interest to the next generation Electron Ion Colliders. GaAs prepared by the standard activation method, which is the most widely used spin-polarized photocathode, is notorious for its vacuum sensitivity and short operational lifetime. To improve the lifetime of GaAs photocathodes, we activated GaAs by Cs2Te, a material well known for its robustness. We confirmed the Cs2Te layer forms negative electron affinity on GaAs with a factor of 5 improvement in lifetime. Furthermore, the new activation method had no adverse effect on spin-polarization. Considering Cs2Te forms much thicker activation layer (~ 2 nm) compared to the standard activation layer (~ monolayer), our results trigger a paradigm shift on new activation methods with other robust materials that were avoided for their thickness.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML025  
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TUPML026 Multi-photon Photoemission and Ultrafast Electron Heating in Cu Photocathodes at Threshold photon, cathode, laser, radiation 1593
 
  • J. Bae, L. Cultrera
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • I.V. Bazarov, J.M. Maxson
    Cornell University, Ithaca, New York, USA
  • S.S. Karkare, H.A. Padmore
    LBNL, Berkeley, California, USA
  • P. Musumeci, X.L. Shen
    UCLA, Los Angeles, California, USA
 
  Funding: U.S. National Science Foundation under award PHY-1549132, the Center for Bright Beams.
Operating photocathodes near the photoemission threshold holds the promise of yielding small intrinsic emittance, at the cost of significantly reduced quantum efficiency. In modern femtosecond photoemission electron sources, this requires a very high intensity (10s of GW/cm2) to extract a useful quantity of electrons. At this intensity, the electron occupation function is far from equilibrium and evolves rapidly on sub-ps timescales. Thus, ultrafast laser heating and multiphoton photoemission effects may play a significant role in emission, thereby increasing the minimum achievable emittance. In this work, we use a Boltzmann equation approach to calculate the non-equilibrium occupation function evolution in time for a copper photocathode, yielding a prediction of quantum efficiency and mean transverse energy as a function of input intensity.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML026  
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TUPML027 Barium Tin Oxide Ordered Photocathodes: First Measurements and Future Perspectives photon, cathode, laser, emittance 1597
 
  • A. Galdi, E. B. Lochocki, H. Paik, C.T. Parzyck, D. G. Schlom, K.M. Shen
    Cornell University, Ithaca, New York, USA
  • G. Adhikari, W.A. Schroeder
    UIC, Chicago, Illinois, USA
  • I.V. Bazarov, L. Cultrera, W. H. Li, J.M. Maxson, C. M. Pierce
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Funding: This work was supported by the U.S. National Science Foundation under Award PHY-1549132, the Center for Bright Beams.
Single crystalline photocathodes with small electron effective mass are supposed to enable ultra-low emittance beams, by taking advantage of the conservation of transverse (crystal) momentum. We present a preliminary study on photoemission from epitaxial films of La-doped BaSnO3 with (100) orientation. We demonstrate here the possibility of generating and characterizing electron beams by exciting photoelectrons solely from the conduction band. We report quantum efficiency and mean transverse energy meaurements as a function of photon energy from the bare and Cs-activated La-doped BaSnO3 surface.
 
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TUPML028 Photocathodes R&D for High Brightness and Highly Polarized Electron Beams at Cornell University cathode, emittance, gun, simulation 1601
 
  • L. Cultrera, J. Bae, A.C. Bartnik, I.V. Bazarov, R. Doane, A. Galdi, C.M. Gulliford, W. H. Li, J.M. Maxson, S.A. McBride, T.P. Moore, C. M. Pierce, C. Xu
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Cornell University is a leader in the development of photocathode materials for the production of high brightness electron beam sources for applications in large scale accelerators and small scale electron scattering experiments. During the last year we have also included Mott polarimetry to investigate long lifetime spin-polarized photocathodes materials. Another thrust of our laboratory is the exploration of ultra low emittance photocathodes at cryogenic temperatures, for which we are building a novel LHe cryogenic electron source. We will review updates from our lab across each of these areas.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML028  
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TUPML029 Novel Photocathode Geometry Optimization: Field Enhancing Photoemission Tips cathode, emittance, solenoid, simulation 1605
 
  • W. H. Li, I.V. Bazarov, C.M. Gulliford, J.M. Maxson
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Funding: This work was supported by the U.S. National Science Foundation under award PHY-1549132, the Center for Bright Beams.
For photoemission sources, the extraction electric field defines the maximum achievable emission current, and hence the maximum achievable beam brightness. Recently, interest has been growing in studying photocathodes with non-flat geometries to produce local field enhancements in excess of what can be achieved with large area flat cathodes. However, such geometries cause image charge effects which require self-consistent field solvers to correctly simulate. We present a novel simulation framework which combines a full particle in cell field solver (WARP) with a fast adaptive mesh space charge particle tracker (GPT) and a parallel multi-objective genetic optimizer to explore photocathode geometries for ultra high brightnesses. A first application of this technique is also shown, namely the use of field enhanced photoemission tips to create bright beams for ultra-fast electron diffraction.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML029  
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TUPML030 Optimisation of D- Ion Production in a Multicusp Ion Source plasma, ion-source, extraction, dipole 1609
 
  • A.M. George, M.P. Dehnel, S.V. Melanson, D.E. Potkins
    D-Pace, Nelson, British Columbia, Canada
  • N. Broderick
    University of Auckland, Auckland, New Zealand
  • H.C. McDonald, C. Philpott
    BSL, Auckland, New Zealand
 
  D-Pace's multicusp ion source achieves high beam cur-rents for negative hydrogen ions in both the TRIUMF-licensed filament-powered ion source (~18 mA) and the University of Jyväskylä-licensed RF-powered ion source (~8 mA) [1]. It is well known that ion sources producing negative deuterium ions achieve lower beam currents compared to similar negative hydrogen ion sources and indeed we have found that negative deuterium ion beam currents in our sources are typically 1/3 that of negative hydrogen beam currents. The reasons behind this are not completely understood, but factors such as the magnetic field strength and the electron temperature are believed to play a major role and offer the potential for significant optimisation. In this paper, we look into the issues surrounding swapping of deuterium for hydrogen in our ion source by studying the properties of plasmas and extracted currents with different magnetic field strengths and gas flows.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML030  
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TUPML031 Characterization of Polarization-Dependent Emittance From an Array of Au Nanorods using Velocity Map Imaging Spectrometer laser, polarization, emittance, experiment 1612
 
  • H. Ye, F.X. Kärtner, S. T. Trippel
    Deutsches Elektronen Synchrotron (DESY) and Center for Free Electron Science (CFEL), Hamburg, Germany
  • A. Fallahi, J. Küpper, O. Muecke
    CFEL, Hamburg, Germany
  • F.X. Kärtner
    MIT, Cambridge, Massachusetts, USA
  • F.X. Kärtner, J. Küpper, S. T. Trippel, H. Ye
    The Hamburg Center for Ultrafast Imaging, University of Hamburg, hamburg, Germany
  • J. Küpper, G.M. Rossi
    DESY, Hamburg, Germany
  • H. Ye
    University of Hamburg, Hamburg, Germany
 
  Electron beams of high quality, e.g., low emittance, are of crucial importance for cutting-edge scientific instruments, such as x-ray free electron lasers (XFELs) and ultrafast electron diffraction (UED) setups. A velocity-map-imaging (VMI) spectrometer was implemented to characterize the intrinsic root-mean-square (rms) normalized emittance from photocathodes. The spectrometer operated in both, spatial map imaging (SMI) and VMI modes. Therefore, spatial- and velocity-coordinates were recorded independently and quickly. The technique allows for fast complete emittance measurements, within minutes. A 75 μm pitch array of Au nanorods of dimension 100×30~nm, was studied under strong-field-emission regime by 100 fs 1 kHz 1.3 μm laser pulses with a 300×30 μm2 focus spot size on the sample. A patterned electron bunch was observed, each emitted from a single nanorod within the array. A polarization dependent photoemission study was performed showing a smaller rms-normalized divergence of 0.8 mrad with the laser polarization normal to the sample surface, compared to 1.15 mrad for the parallel case.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML031  
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TUPML035 FELs Driven by Laser Plasma Accelerators Operated with Transverse Gradient Undulators undulator, FEL, radiation, laser 1615
 
  • F. Jafarinia, R.W. Aßmann, F. Burkart, U. Dorda, C. Lechner, B. Marchetti, R. Rossmanith, P.A. Walker
    DESY, Hamburg, Germany
  • A. Bernhard, R. Rossmanith
    KIT, Karlsruhe, Germany
 
  Laser Plasma Accelerators produce beams with a significantly higher energy spread (up to a few percent) compared to conventional electron sources. The high energy spread increases significantly the gain length when used for an FEL. In order to reduce the gain length of the FEL the Transverse Gradient Undulators (TGUs) instead of conventional undulators were proposed. In this paper the limits of this concept are discussed using a modified Version of the GENESIS program*.
*Zhirong Huang et al., Phys. Rev. Lett., 109, 204801
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML035  
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TUPML039 First Order Sensitivity Analysis of Electron Acceleration in Dual Grating Type Dielectric Laser Accelerator Structures laser, simulation, experiment, emittance 1626
 
  • F. Mayet, R.W. Aßmann, U. Dorda, W. Kuropka
    DESY, Hamburg, Germany
  • W. Kuropka, F. Mayet
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
 
  Funding: Gordon and Betty Moore Foundation. Grant GBMF4744
Symmetrically driven dual-grating type DLA (Dielectric Laser Accelerator) linac structures allow for in-channel electric field gradients on the order of GV/m at optical wavelengths. In this work we study the sensitivity of important final beam parameters like mean energy, energy spread and transverse emittance on DLA drive laser as well as input beam parameters. To this end a fast specialized particle tracking code (DLATracker) is used to compute the so called first order sensitivity indices based on a large number of Monte Carlo simulation runs of an exemplary external injection based DLA experiment. The results of this work point out important stability constraints on the drive laser setup and the externally injected electron beam.
 
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TUPML040 Status of the Transverse Diagnostics at FLASHForward plasma, laser, wakefield, diagnostics 1630
 
  • P. Niknejadi, R.T.P. D'Arcy, A. Knetsch, V. Libov, A. Martinez de la Ossa, J. Osterhoff, K. Poder, L. Schaper
    DESY, Hamburg, Germany
  • M. Kaluza, M.B. Schwab, A. Sävert, C. Wirth
    IOQ, Jena, Germany
  • M. Kaluza
    HIJ, Jena, Germany
  • T.J. Mehrling
    LBNL, Berkeley, USA
  • C.A.J. Palmer
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
 
  Funding: Helmholtz Institute, Bundesministerium für Bildung und Forschung, and European Union‘s Horizon 2020 research and innovation program.
Density modulations in plasma caused by a high-intensity laser or a high charge density electron pulse can generate extreme acceleration fields. Acceleration of electrons in such fields may produce ultra-relativistic, quasi-monoenergetic, ultra-short electron bunches over distances orders of magnitudes shorter than in state-of-the-art radio-frequency accelerators. FLASHForward is such a beam-driven plasma wakefield accelerator (PWFA) project at DESY with the goal of producing, characterizing, and utilizing such beams. Temporal characterization of the acceleration process is of crucial importance for improving the stability and control in PWFA beams. While measurement of the transient field of the femtosecond bunch in a single shot is challenging, in recent years novel techniques with great promise have been developed** ***. This work discusses the plans and status of the transverse diagnostics at FLASHForward.
*A. Aschikhin et. al., NIMA , Volume 806 (11 January 2016) pp. 175-183.
**A. Buck et al., Nature Physics 7, (2011) 543.
***C. J. Zhang et al., Phys. Rev. Lett. 119 (2017) 064801.
 
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TUPML041 Two-Stage Laser-Driven Plasma Acceleration With External Injection for EuPRAXIA plasma, laser, acceleration, wakefield 1634
 
  • E.N. Svystun, R.W. Aßmann, U. Dorda, A. Ferran Pousa, T. Heinemann, B. Marchetti, P.A. Walker, M.K. Weikum, J. Zhu
    DESY, Hamburg, Germany
  • A. Ferran Pousa, T. Heinemann, A. Martinez de la Ossa
    University of Hamburg, Hamburg, Germany
  • T. Heinemann
    USTRAT/SUPA, Glasgow, United Kingdom
 
  The EuPRAXIA (European Particle Research Accelerator with eXcellence In Applications) project aims at producing a conceptual design for the worldwide plasma-based accelerator facility, capable of delivering multi-GeV electron beams with high quality. This accelerator facility will be used for various user applications such as compact X-ray sources for medical imaging and high-energy physics detector tests. EuPRAXIA explores different approaches to plasma acceleration techniques. Laser-driven plasma wakefield acceleration with external injection of an RF-generated electron beam is one of the basic research directions of EuPRAXIA. We present studies of electron beam acceleration to GeV energies by a two-stage laser wakefield acceleration with external injection from an RF accelerator. Electron beam injection, acceleration and extraction from the plasma, using particle-in-cell simulations, are investigated.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML041  
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TUPML042 Accurate Modeling of the Hose Instability in Plasma Based Accelerators plasma, damping, simulation, wakefield 1638
 
  • T.J. Mehrling, C. Benedetti, E. Esarey, W. Leemans, C.B. Schroeder
    LBNL, Berkeley, USA
 
  Funding: US Department of Energy Contract No. DE-AC02-05CH11231
The hose instability is a long standing challenge for plasma-based accelerators. It is seeded by initial transverse asymmetries of the beam or plasma phase space distributions. The beam centroid displacement is thereby amplified during the propagation in the plasma, which can lead to an unstable acceleration process. A witness beam can itself cause hosing and/or may be affected by the hosing of the drive beam. The accurate study of hosing including a witness beam is of utmost importance to facilitate stable plasma-based accelerators. In this contribution, we discuss novel methods for the mitigation of hosing and present a new model for the evolution of the plasma centroid, which enables the accurate investigation of the hose instability of drive and witness beam pair in the nonlinear blowout regime. This work enables more precise and comprehensive studies of hosing and hence, for the potential stabilization of future compact plasma-based accelerators.
 
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TUPML045 Segmented Terahertz Driven Device for Electron Acceleration acceleration, laser, linac, controls 1642
 
  • D. Zhang
    DESY, Hamburg, Germany
  • A-L. Calendron, H. Cankaya, M. Fakhari, A. Fallahi, Y. Hua, N.H. Matlis, X. Wu, L.E. Zapata
    CFEL, Hamburg, Germany
  • M. Hemmer, F.X. Kärtner
    Deutsches Elektronen Synchrotron (DESY) and Center for Free Electron Science (CFEL), Hamburg, Germany
  • F.X. Kärtner
    MIT, Cambridge, Massachusetts, USA
 
  Funding: ERC Synergy Grant AXSIS (609920), Deutsche Forschungsgemeinschaft (SPP1840 SOLSTICE and CUI EXC1074), and Gordon and Betty Moore foundation (ACHIP GBMF4744)
We present a segmented THz based device (STEAM) capable of performing multiple high-field operations on the 6D-phase-space of ultrashort electron bunches. Using only a few microjoules of single-cycle THz radiation, we have shown record THz-based acceleration of >30 keV of an incoming 55keV electron beam, with a peak acceleration field gradient of around 70 MV/m that is comparable with that from a conventional RF accelerator. It can be scaled up to GV/m gradients that can accelerate electrons into the MeV regime. At the same time, the STEAM device can also manipulate the electrons that show high focusing gradient (2 kT/m), compression of electron bunches down to 100 fs and streaking gradient of 140 μrad/fs, which offers temporal profile characterizations with resolution below 10 fs. The STEAM device can be fabricated with regular mechanical machining tools and supports real-time switching between different modes of operation. It paves the way for the development of THz-based compact electron guns, accelerators, ultrafast electron diffractometers and Free-Electron Lasers.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML045  
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TUPML046 Characterization of Self-Modulated Electron Bunches in an Argon Plasma plasma, experiment, solenoid, focusing 1645
 
  • M. Groß, P. Boonpornprasert, Y. Chen, J. Engel, J.D. Good, H. Huck, I.I. Isaev, M. Krasilnikov, X. Li, O. Lishilin, G. Loisch, R. Niemczyk, A. Oppelt, H.J. Qian, Y. Renier, F. Stephan, Q.T. Zhao
    DESY Zeuthen, Zeuthen, Germany
  • R. Brinkmann, A. Martinez de la Ossa, J. Osterhoff
    DESY, Hamburg, Germany
  • F.J. Grüner
    CFEL, Hamburg, Germany
  • F.J. Grüner, A. Martinez de la Ossa
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • T.J. Mehrling, C.B. Schroeder
    LBNL, Berkeley, USA
  • I. Will
    MBI, Berlin, Germany
 
  The self-modulation instability is fundamental for the plasma wakefield acceleration experiment of the AWAKE (Advanced Wakefield Experiment) collaboration at CERN where this effect is used to generate proton bunches for the resonant excitation of high acceleration fields. Utilizing the availability of flexible electron beam shaping together with excellent diagnostics including an RF deflector, a supporting experiment was set up at the electron accelerator PITZ (Photo Injector Test facility at DESY, Zeuthen site), given that the underlying physics is the same. After demonstrating the effect* the next goal is to investigate in detail the self-modulation of long (with respect to the plasma wavelength) electron beams. In this contribution we describe parameter studies on self-modulation of a long electron bunch in an argon plasma. The plasma was generated with a discharge cell with densities in the 1013 cm-3 to 1015 cm-3 range. The plasma density was deduced from the plasma wavelength as indicated by the self-modulation period. Parameter scans were conducted with variable plasma density and electron bunch focusing.
* M. Gross et al., "Observation of the self-modulation instabil-ity via time-resolved measurements", accepted for publication at Phys. Rev. Lett.
 
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TUPML047 Optimisation of High Transformer Ratio Plasma Wakefield Acceleration at PITZ plasma, wakefield, acceleration, laser 1648
 
  • G. Loisch, P. Boonpornprasert, J.D. Good, M. Groß, H. Huck, M. Krasilnikov, O. Lishilin, A. Oppelt, Y. Renier, F. Stephan
    DESY Zeuthen, Zeuthen, Germany
  • R. Brinkmann, A. Martinez de la Ossa, J. Osterhoff
    DESY, Hamburg, Germany
  • F.J. Grüner
    CFEL, Hamburg, Germany
  • F.J. Grüner, A. Martinez de la Ossa
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
 
  The transformer ratio, the ratio between maximum accelerating field and maximum decelerating field in the driving bunch of a plasma wakefield accelerator (PWFA), is one of the key aspects of this acceleration scheme. It not only defines the maximum possible energy gain of the PWFA but it is also connected to the maximum percentage of energy that can be extracted from the driver, which is a limiting factor for the efficiency of the accelerator. Since in linear wakefield theory a transformer ratio of 2 cannot be exceeded with symmetrical drive bunches, any ratio above 2 is considered high. After the first demonstration of high transformer ratio acceleration in a plasma wakefield at PITZ, the photoinjector test facility at DESY, Zeuthen site, limiting aspects of the transformer ratio are under investigation. This includes e.g. the occurrence of bunch instabilities, like the transverse two stream instability, or deviations of the experimentally achieved bunch shapes from the ideal.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML047  
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TUPML049 Comparison of Fourier Signal and Error Analysis Techniques for Identifying the Self-Modulation Frequency of a Proton Bunch plasma, proton, wakefield, experiment 1651
 
  • S.J. Gessner
    CERN, Geneva, Switzerland
 
  The AWAKE experiment uses an ultra-high energy proton beam to create large amplitude wakefields for accelerating electrons in plasma. The proton beam is much longer than the plasma wavelength, and must be formed into small, sub- wavelength sized beamlets before it can effectively drive the wake. These beamlets are referred to as micro-bunches and are formed by the plasma self-modulation instability. An im- portant aspect of AWAKE is to measure the depth, frequency, and stability of the modulation, as this provides critical in- formation for establishing the presence of a high-amplitude wakefield driven by a self-modulation proton bunch. This paper discusses Fourier Analysis techniques for measuring the modulation frequency and compares error estimation techniques that work for both small and large datasets.
On behalf of the AWAKE Collaboration.
 
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TUPML051 Studies of Collision and Compression of Pulsed Plasmas Generated by Coaxial Accelerators plasma, experiment, ion-source, simulation 1653
 
  • T. Manegold, C. Benzing, M. Iberler, J. Jacoby, P. Mahmoodi Tavana, A. Müller-Münster, B. Podßus
    IAP, Frankfurt am Main, Germany
 
  This contribution is about our recent studies of collision and compression of plasma sheaths, generated by coaxial plasma accelerators. One application is the development of a pulsed ion source producing high ion currents, coming along with high electron densities. The experiment is built up of an energy storage with up to 1,35kJ with a 2% Hydrogen in Helium gas mixture as working gas. The small fraction of Hydrogen is necessary to use the linear Stark-broadening of the H-line to determine the electron density, which is in the range up to 1015cm-3. By the collision of two plasma sheaths in an angle of 180°, the electron density has been increased by a factor of 2.5 compared to the single plasma sheath. As an alternative, the compression of the plasma by funnel geometries has been studied. As has been found, the achieved electron densities are more than a magnitude higher, compared to the values of the plasma collision. Thus, the H-line is broadened too high to be used. Alternatively, the broadening of a copper line by the quadratic Stark-effect has been calibrated and used to determine those high electron densities of about 1018cm-3.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML051  
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TUPML054 Microbeam Irradiation System with a Dielectric Laser Accelerator for Radiobiology Research laser, accelerating-gradient, radiation, cavity 1664
 
  • K. Koyama
    KEK, Ibaraki, Japan
  • Z. Chen
    The University of Tokyo, Tokyo, Japan
  • T. Takahashi
    The University of Tokyo, The School of Engineering, Tokyo, Japan
  • M. Uesaka
    The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
 
  Funding: This work was supported by KAKENHI (Grant-in-Aid for Scientific Research)15H03595 and partly supported by NIMS Nanofabrication Platform in Nanotechnology Platform Project sponsored by the MEXT, Japan.
A laser micro-irradiation (LMI) system is widely used in the field of radiobiology because of its acceptably small size. However, damage in a cell nucleus caused by the LMI system does not necessarily simulate a radiation effect. If the laser of the LMI system is replaced with a small-scale 1MeV-class accelerator such as a dielectric laser accelerator (DLA), experiments might be performed under conditions that are more realistic. The desirable configuration of the DLA for a compact micro-beam irradiation system is that laser pulses are transported to a dielectric structure by single-mode optical fibers and the laser energy is accumulated in an accelerator channel. The long and low-intensity laser pulse of 100 MW/cm2, 10ps and a resonator with Q=104 are capable of producing the light intensity of 1 TW/cm2. The long laser pulse, i.e., low laser induced damage threshold intensity, decreases the acceleration gradient to about 1/3 of the ultra-short pulse irradiation of 100 fs. The length of the accelerator at long-laser pulse might be within the allowable range of several cm. The resonator scheme is useful only for the sub-relativistic regime because of the acceleration gradient.
 
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TUPML059 Slice Energy Spread Optimization for a 5 GeV Laser-Plasma Accelerator plasma, laser, beam-loading, simulation 1670
 
  • X. Li, P.A.P. Nghiem
    IRFU, CEA, University Paris-Saclay, Gif-sur-Yvette, France
  • A. Mosnier
    CEA/IRFU, Gif-sur-Yvette, France
 
  GeV-scale laser-plasma accelerating modules can be integrated into a multi-staged plasma linac for driving compact X-ray light sources or future colliders. Such a plasma module, operating in the quasi-linear regime, has been designed for the 5 GeV laser plasma acceleration stage (LPAS) of the EuPRAXIA project. Although it can be employed to optimize the total energy spread, the beam loading effect introduces an non-negligible slice energy spread to the beam. In this paper, we study the slice energy spread from linear theory, establishing a relationship between it and the laser-plasma parameters. To reduce the slice energy spread, simulations have been carried out for various plasma densities and laser strengths. The results will be discussed and compared with the theory.  
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TUPML060 Three-Dimentional Spiral Beam Injection for a Compact Storage Ring injection, solenoid, experiment, coupling 1673
 
  • H. Iinuma
    Ibaraki University, Hitachi, Ibaraki, Japan
  • M.R. Abdul
    Sokendai, Ibaraki, Japan
  • Y. Fukao, K. Furukawa, H. Hisamatsu, T. Mibe, H. Nakayama, S. Ohsawa, K. Oide, K. Sasaki
    KEK, Tsukuba, Japan
 
  Funding: This work is supported by JSPS KAKENHI Grant Numbers JP26287055 and JP 23740216.
A newly developed three-dimensional spiral injection scheme for beam insertion into a compact (medical MRI size) solenoidal storage ring is introduced. This is a one of key R&D items for a new planned muon g-2/EDM experiment at J-PARC, which aims to measure g-2 to a factor 5 better statistical precision and a factor of 100 better sensitivity for the electric dipole moment measurement (EDM) compared to the previous experiments. The new scheme provides a smooth injection utilizing a radial solenoidal fringe field, without causing any error field in the storage volume. Magnetic pulsed kicker will guide and set the beam in the storage field volume. The strongest point of this new scheme is that any source of the electric field is removed in this scheme to perform ideal EDM measurement. We have performed a test bench experimental work to demonstrate a feasibility of this new injection scheme. Instead of the muon beam, we inject electron beam, from an electron-gun, into the solenoid magnet, and detect three-dimensional spiral beam trajectory inside of the storage chamber by CCD camera. We will discuss outline of a new injection scheme and the latest results from the test bench works.
*H. Iinuma et al.,Nuclear Instruments and Methods in Physics Research A, 832, 51-62 (2016)
 
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TUPML061 Study of Mean Transverse Energy of (N)UNCD with Tunable Laser Source solenoid, photon, cathode, laser 1677
 
  • G. Chen
    IIT, Chicago, Illinois, USA
  • G. Adhikari, W.A. Schroeder
    UIC, Chicago, Illinois, USA
  • S.P. Antipov, C.-J. Jing, K. Kovi
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • S.V. Baryshev
    ANL, Argonne, Illinois, USA
  • L.K. Spentzouris
    Illinois Institute of Technology, Chicago, Illinois, USA
 
  Funding: NSF grant No. NSF-1739150, DOE SBIR program grant No. DE-SC0013145, NSF grant No. PHYS-1535279, DOE Contract No. DE-AC02-06CH11357.
There is a strong motivation to develop and understand novel materials with the potential to be utilized as photocathodes, as these could have desirable photoemission properties for research and industrial applications. Nitrogen-incorporated ultrananocrystalline diamond ((N)UNCD) photocathodes have potential to become a material of choice for photocathode applications*. (N)UNCD has high quantum efficiency when processed in hydrogen plasma*, low surface roughness, and high electron conductivity through the bulk**. The mean transverse energy (MTE) was calculated for (N)UNCD thin films using the double-solenoid scan method. (N)UNCD thin film with thickness of 160nm was deposited on highly-doped silicon substrate. Studies of the MTE of a (N)UNCD sample were done using a tunable laser source with photon energies of 3.56 eV to 5.26 eV. These results are presented.
* K.J. Pérez Quintero et al., Appl. Phys. Lett. 105, 123103 (2014).
** S. Bhattacharyya et al., Appl. Phys. Lett. 79, 1441 (2001)
 
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TUPML071 Experimental Performance of the Chopper for the ESS Linac high-voltage, linac, experiment, proton 1709
 
  • G. Torrisi, L. Allegra, A.C. Caruso, G. Castro, L. Celona, G. Gallo, S. Gammino, O. Leonardi, A. Longhitano, D. Mascali, L. Neri, S. Passarello, G. Sorbello
    INFN/LNS, Catania, Italy
 
  At the Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud (INFN-LNS) the beam commissioning of the high intensity Proton Source for the European Spallation Source (PS-ESS) was completed in November 2017. The ESS requires a high intensity proton beam (74 mA pulsed at 14 Hz of repetition rate), with fast Beam pulse rise/fall time (< 20 μs). In order to meet the project requirement, an electrostatic chopping system has been used in the Low Energy Beam Transport (LEBT). The design of the control system was done also to be the main element of the fast beam abort system and taking into account the radiation issue in the accelerator tunnel. This paper describes the performances of the chopper. The experimentally-achieved rise/fall times of the beam pulses measured by using an AC Current Transformer (ACCT) at the end of the LEBT collimator, are presented. An experimental investigation of the effects of different amounts and types of gas injected into the LEBT (for the sake of space charge compensation) has been carried out with respect to the beam and chopper parameters.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML071  
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TUPML074 Resonant Excitation of Accelerating Field in Dielectric Corrugated Waveguide simulation, wakefield, experiment, GUI 1715
 
  • A. Lyapin, S.T. Boogert, K. Lekomtsev
    JAI, Egham, Surrey, United Kingdom
  • A. Aryshev
    KEK, Ibaraki, Japan
  • A.A. Tishchenko
    MEPhI, Moscow, Russia
 
  Funding: This project has received funding from the European Union Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 655179.
Beam driven dielectric wakefield accelerators (DWAs) [*] typically operate in the terahertz frequency range, which pushes the plasma breakdown threshold for surface electric fields into the multi GV/m range. DWA technique allows one to accommodate a significant amount of charge per bunch, and opens access to conventional fabrication techniques for the accelerating structures. Resonant excitation of coherent Cherenkov radiation in DWA by a multi-bunch beam was used for selective resonant mode excitation [**] and enhancement of accelerating wakefield [***]. We investigate the resonant excitation of Cherenkov Smith-Purcell radiation [****] in a corrugated cylindrical waveguide by a multi-bunch electron beam. The accelerating field is calculated using Particle in Cell simulations and some basic post-processing is done in order to estimate the possible enhancement of the accelerating field. The aim of this work is to investigate regimes of the resonant excitation that can potentially produce accelerating gradients above 1 GV/m.
* C. Jing, Rev. Acc. Phys. and Tech. 9, 127 (2016).
** G. Andonian, APL 98, 202901 (2011).
*** J.G. Power, PRSTAB 3, 101302 (2000).
**** A.A. Ponomarenko, A.A. Tishchenko, NIMB 309, 223 (2013).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML074  
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TUPML076 Installation, Commissioning and Characterization of EBIS-SC as a Short Pulsed Proton Source at KOMAC extraction, proton, MMI, neutron 1721
 
  • S. Lee, Y.-S. Cho, H.S. Kim, H.-J. Kwon
    Korea Atomic Energy Research Institute (KAERI), Gyeongbuk, Republic of Korea
 
  Funding: This work has been supported through KOMAC operation fund of KAERI by MSIT (Ministry of Science and ICT)
Neutron source is applicable to various fields in basic/applied science and industries. There are several neutron sources in the world such LENS, SNS, J-PARC, ISIS and ESS either for short or long pulsed neutron. At Korea Multipurpose Accelerator Complex (KOMAC), to provide wide ranges of research opportunities to beam user, a 100 MeV proton linac based pulsed neutron source is planned for both long and short pulses of neutron source. Currently, the 100 MeV proton linac is operational with a 2 ms long pulsed proton injector, i.e. a microwave ion source. We will upgrade our injector by combining the already existing microwave ion source with a EBIS-SC (Superconducting Electron Beam Ion Source from Dreebit GmbH) for short pulses (< 1 us) of proton. This planned injector will work one at the time and provide long/short pulses of accelerated proton hitting a target to emit correspondingly long/short neutron pulses. Main modification on the proton injector is the EBIS-SC, so in this paper we report the installation, and commission of the EBIS-SC test bench at KOMAC. And the characterization of the EBIS-SC is described in detail.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML076  
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TUPML079 A Start to End Simulation of the Laser Plasma Wakefield Acceleration Experiment at ESCULAP plasma, laser, acceleration, wakefield 1731
 
  • K. Wang, C. Bruni, K. Cassou, V. Chaumat, N. Delerue, D. Douillet, S. Jenzer, V. Kubytskyi, P. Lepercq, H. Purwar
    LAL, Orsay, France
  • E. Baynard, M. Pittman
    CLUPS, Orsay, France
  • J. Demailly, O. Guilbaud, S. Kazamias, B. Lucas, G. Maynard, O. Neveu, D. Ros
    CNRS LPGP Univ Paris Sud, Orsay, France
  • D. Garzella
    CEA, Gif-sur-Yvette, France
  • R. Prazeres
    CLIO/ELISE/LCP, Orsay, France
 
  We present a start to end (s2e) simulation of the Laserplasma Wake Field Accelerator (LPWA) foreseen as the ESCULAP project. We use a photo injector to produce a 5 MeV 10 pC electron bunch with a duration of 1 ps RMS, it is boosted to 10 MeV by a S-band cavity and then compressed to 74 fs RMS (30 fs FWHM) by a magnetic compression chicane (dogleg). After the dogleg, a quadrupole doublet and a triplet are utilized to match the Twiss parameters before injecting into the subsequent plasma wakefield. A 40 TW laser is used to excite plasma wakefield in the 10 cm plasma cell. An optimized configuration has been determined yielding at the plasma exit an electron beam at 180 MeV with energy spread of 4.2%, an angular divergence of 0.6 mrad and a duration of 4 fs.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML079  
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WEXGBD1 Development of Very Short Period Undulators undulator, radiation, vacuum, factory 1735
 
  • S. Yamamoto
    KEK, Ibaraki, Japan
 
  Scientists and engineers at KEK have developed undulator magnets having very short period lengths. Magnet plates 100mm and 152mm long with 4-mm period length have been successfully fabricated. They produce an undulator field of approximately 4kG at a gap of 1.6mm. The magnetic field characterization shows that the undulator field is satisfactory in quality for a very short period undulator. KEK has recently installed a short-period undulator at a 50-MeV linac and observed a first light, and will soon start an experiment using a short-period undulator with laser-accelerated electrons for future table-top XFELs. This invited talk summarizes the current status, and experimental activities and results related to short-period undulators and table-top FELs.  
slides icon Slides WEXGBD1 [3.515 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEXGBD1  
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WEXGBD2 Pulse-by-Pulse Multi-XFEL Beamline Operation with Ultra-Short Laser Pulses FEL, optics, operation, undulator 1740
 
  • T. Hara, T. Inagaki, H. Maesaka, Y. Otake, H. Tanaka, K. Togawa
    RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
  • K. Fukami
    JASRI/SPring-8, Hyogo-ken, Japan
  • T. Hasegawa, O. Morimoto, S. Nakazawa, M. Yoshioka
    SES, Hyogo-pref., Japan
  • H. Kawaguchi, Y. Kawaguchi
    Nichicon (Kusatsu) Corporation, Shiga, Japan
  • C. Kondo
    JASRI, Hyogo, Japan
 
  The parallel operation of multiple beamlines is an important issue to expand the opportunity of user experiments for linac based FELs. At SACLA, the parallel operation of three beamlines, BL1~3, has been open to user experiments since September 2017. BL1 is a soft x-ray beamline driven by a dedicated accelerator, which is a former SCSS linac, and BL2 and 3 are XFEL beamlines, which share the electron beam from the SACLA main linac. In the parallel operation, a kicker magnet with 10 ppm stability (peak-to-peak) switches the two XFEL beamlines at 60 Hz from pulse to pulse. To ensure wide spectral tunability and optimize the laser performance, the energies and lengths of the electron bunches are independently adjusted for the two beamlines according to user experiments. Since the electron bunch of SACLA has typically 10~15 fs (FWHM) in length and its peak current exceeds 10 kA, the CSR effect at a dogleg beam transport to BL2 is quite significant. In order to suppress the CSR effects, an isochronous and achromatic lattice based on two DBA structures was introduced. In this talk, the multiple XFEL beamline operation and achieved laser performance are presented.  
slides icon Slides WEXGBD2 [9.708 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEXGBD2  
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WEXGBE2 Compensation of Insertion Device Induced Emittance Variations in Ultralow Emittance Storage Rings emittance, wiggler, lattice, photon 1751
 
  • F. Sannibale, S.C. Leemann, H. Nishimura, D. Robin, C. Steier, C. Sun, M. Venturini
    LBNL, Berkeley, California, USA
 
  Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231.
With the advent of multi-bend achromat lattices, extremely low emittances are to become the norm in storage ring-based X-ray photon sources. In these lattices, the ratio of beam energy lost to radiation in the Insertion Devices (IDs) to the overall beam energy loss is relatively larger than in 3rd generation light sources. As a result, these machines are more sensitive to the energy loss variations occurring as the users operate variable-gap IDs and to the concurrent variations in radiation damping time, equilibrium emittance, and ultimately transverse properties of the beam. With possibly tens of variable gap IDs continuously and independently varying their gaps to meet the experiment needs, the resulting variation in emittance and beam sizes can be significant and can jeopardize the experimental performance in some of the beamlines. In this paper we describe and discuss possible methods for compensating such emittance variations and maintaining constant transverse beam properties for the experiments.
 
slides icon Slides WEXGBE2 [4.543 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEXGBE2  
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WEXGBF1 Testing of the ESS MB-IOT Prototypes klystron, linac, cavity, operation 1759
 
  • M. Jensen
    ESS, Lund, Sweden
  • C. Bel, A. Beunas, D. Bussiere, P. Cacheux, V. Hermann, J.C. Racamier, C. Robert
    TED, Thonon, France
  • M. Boyle, H. Schult
    L-3, Williamsport, Pennsylvania, USA
  • G. Cipolla, E. Montesinos, M.S.B. Sanchez Barrueta
    CERN, Geneva 23, Switzerland
  • T. Kimura, P.E. Kolda, P. Krzeminski, L. Kurek, S. Lenci, O.S. Sablic, L. Turek, C. Yates
    CPI, Palo Alto, California, USA
  • M.F. Kirshner
    LANL, Los Alamos, New Mexico, USA
  • R.D. Kowalczyk, A.V. Sy, B.R. Weatherford
    SLAC, Menlo Park, California, USA
  • A. Zubyk
    L3 EDD, Williamsport, USA
 
  ESS is considering the use of MB-IOTs for parts of the high-beta linac. Two prototypes have been built by indus-try, namely L3 and CPI/Thales and have passed the factory acceptance test with excellent results. Both tubes will go through further extensive testing at CERN for ESS follow-ing delivery and a final decision on tube technology will be taken in April 2018. This invited talk presents the back-ground for the technical decision of IOTs vs klystrons, associated impact for ESS, and latest plans for industrial production of these IOTs for ESS.  
slides icon Slides WEXGBF1 [9.836 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEXGBF1  
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WEYGBD2 Status of the Radiation Damage on the European XFEL Undulator Systems undulator, radiation, FEL, operation 1776
 
  • F. Wolff-Fabris, J. Pflüger
    XFEL. EU, Schenefeld, Germany
  • F. Hellberg
    Stockholm University, Stockholm, Sweden
  • F. Schmidt-Föhre
    DESY, Hamburg, Germany
 
  The European XFEL GmbH is a new X-ray FEL user facility and started lasing in 2017. Three gap movable SASE Undulator Systems are designed to produce FELs with tunable wavelengths from 0.05 to 5.2nm [*,**]. A total of 91 5-m long undulator segments based on hybrid NdFeB permanent magnet technology were tuned respecting tight specifications. Radiation damage due to machine operation affects the magnetic properties of the segments and the quality of the SASE process. An array of dosimeters based on Radfets [***] and Gafchromic films monitors the absorbed doses in every undulator segment and each SASE system is equipped with a 12mm gap diagnostic undulator (DU) which is magnetically re-measured during machine maintenance weeks. Doses up to 4 kGy have been observed and magnetic field degradation higher than 3% is measured. These results permit to estimate the effects of radiation damage and life expectancy of the Undulator Systems based on the precise K-parameter determination for beam operation. We will present the results of magnetic re-measurements on the Undulator Systems, the details of the effects of radiation damage and future plans to maximize the beam quality and operation.
* M. Altarelli et al., Tech. Design Rep. DESY 2006-097, July 2007.
** E. Schneidmiller et al., Eur. XFEL Tech. Rep. TR-2011-006, Sep. 2011.
*** F. Schmidt-Föhre et al., IPAC-2018 contribution.
 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEYGBD2  
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WEYGBD3 The CERN Gamma Factory Initiative: An Ultra-High Intensity Gamma Source photon, factory, neutron, positron 1780
 
  • M.W. Krasny
    LPNHE, Paris, France
  • R. Alemany-Fernández, H. Bartosik, N. Biancacci, P. Czodrowski, B. Goddard, S. Hirlaender, J.M. Jowett, R. Kersevan, M. Kowalska, M.W. Krasny, M. Lamont, D. Manglunki, A.V. Petrenko, M. Schaumann, C. Yin Vallgren, F. Zimmermann
    CERN, Geneva, Switzerland
  • P.S. Antsifarov
    Institute of Spectroscopy, Russian Academy of Science, Troitsk, Moscow, Russia
  • A. Apyan
    ANSL, Yerevan, Armenia
  • E.G. Bessonov
    LPI, Moscow, Russia
  • J. Bieron, K. Dzierzega, W. Placzek, S. Pustelny
    Marian Smoluchowski Institute of Physics, Jagiellonian University, Kraków, Poland
  • D. Budker
    Johannes Gutenberg University Mainz, Institut für Physik, Mainz, Germany
  • K. Cassou, I. Chaikovska, R. Chehab, K. Dupraz, A. Martens, Z.F. Zomer
    LAL, Orsay, France
  • F. Castelli
    Università degli Studi di Milano, Milano, Italy
  • C. Curatolo, L. Serafini
    Istituto Nazionale di Fisica Nucleare, Milano, Italy
  • K. Kroeger
    FSU Jena, Jena, Germany
  • V. Petrillo
    Universita' degli Studi di Milano & INFN, Milano, Italy
  • V.P. Shevelko
    LPI RAS, Moscow, Russia
  • T. Stöhlker
    HIJ, Jena, Germany
  • G. Weber
    IOQ, Jena, Germany
  • Y.K. Wu
    FEL/Duke University, Durham, North Carolina, USA
  • M.S. Zolotorev
    LBNL, Berkeley, California, USA
 
  This contribution discusses the possibility of broadening the present CERN research programme making use of a novel concept of light source. The proposed, Partially Stripped Ion beam driven, light source is the backbone of the Gamma Factory (GF) initiative. It could be realized at CERN by using the infrastructure of the already existing accelerators. It could push the intensity limits of the presently operating light-sources by up to 7 orders of magnitude, reaching fluxes of 1017 photons/s in the interesting gamma-ray energy domain between 1 MeV and 400 MeV. The GF light-source cannot be replaced, in this energy domain, by a FEL source as long as the multi TeV electron beams are not available. Its intensity is beyond the reach of the Inverse Compton Scattering sources. The unprecedented-intensity, energy-tuned gamma beams, together with the gamma-beams-driven secondary beams of polarized leptons, neutrinos, neutrons and radioactive ions are the basic research tools of the proposed Gamma Factory. A broad spectrum of new opportunities, in a vast domain of uncharted fundamental and applied physics territories, could be opened by the Gamma Factory research programme.  
slides icon Slides WEYGBD3 [7.531 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEYGBD3  
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WEYGBE2 Applications of Caustic Methods to Longitudinal Phase Space Manipulation FEL, linac, optics, gun 1790
 
  • T.K. Charles
    The University of Melbourne, Melbourne, Victoria, Australia
  • T.K. Charles
    CERN, Geneva, Switzerland
  • D. Douglas
    JLab, Newport News, Virginia, USA
  • P.H. Williams
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
 
  Longitudinal phase space management is a key feature of recirculating machines. Careful consideration of the longitudinal matching is required not only in order to ensure a high peak current, low energy spread bunch is delivered to the FEL but also to support the deceleration and energy recovery of the spent beam. In a similar manner, longitudinal phase space manipulation can be utilised for pulse shaping in bunch compression, to minimise the influence of CSR-induced emittance growth. In this paper, we present a method for longitudinal phase space matching based upon the avoidance of electron trajectory caustics. Through considering the conditions under which caustics will form, we generate exclusion plots identifying the viable parameter space at numerous positions through beam acceleration and energy recovery. The result is a method for selecting the linear momentum compaction and the higher-order momentum compaction to satisfy the non-caustic condition whilst achieving the bunch compression or lengthening as required.  
slides icon Slides WEYGBE2 [6.292 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEYGBE2  
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WEPAF018 Proposed BPM-Based Bunch Crabbing Angle Monitor cavity, simulation, site, diagnostics 1860
 
  • P. Thieberger, M.G. Minty, C. Montag
    BNL, Upton, Long Island, New York, USA
 
  Funding: This work was supported by Brookhaven Science Associates, LLC, under Contract No. DE-AC02-98CH10886 with the US Department of Energy.
A tilted bunch traversing a button beam profile monitor will produce signals on opposite pickup electrodes that will have different degrees of distortion depending on the tilt angle. In particular, the zero-crossing time difference between the two signals will be approximately proportional to the tilt angle. We perform simulations to study this effect as a possible diagnostic tool for measuring the crabbing angles in a future electron-ion collider.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF018  
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WEPAF019 Fast Readout Algorithm for Cylindrical Beam Position Monitors Providing Good Accuracy for Particle Bunches with Large Offsets simulation, FPGA, collider, pick-up 1864
 
  • P. Thieberger, D.M. Gassner, R.L. Hulsart, R.J. Michnoff, T.A. Miller, M.G. Minty, Z. Sorrell
    BNL, Upton, Long Island, New York, USA
  • A.C. Bartnik
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Funding: This work was supported by Brookhaven Science Associates, LLC, under Contract No. DE-AC02-98CH10886 with the US Department of Energy.
A simple, analytically correct algorithm is developed for calculating 'pencil' beam coordinates using the signals from an ideal cylindrical beam position monitor (BPM) with four pickup electrodes (PUEs) of infinitesimal widths. The algorithm is then applied to simulations of realistic BPMs with finite width PUEs. Surprisingly small deviations are found. Simple empirically determined correction terms reduce the deviations even further. Finally, the algorithm is used to study the impact of beam-size upon the precision of BPMs in the non-linear region. As an example of the data acquisition speed advantage, a FPGA-based BPM readout implementation of the new algorithm has been developed and characterized
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF019  
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WEPAF024 Turn-by-Turn Position Measurements at CNAO with the Libera Spark HR Prototype pick-up, hadron, electronics, instrumentation 1870
 
  • M. Cargnelutti, M. Žnidarčič
    I-Tech, Solkan, Slovenia
  • G.M.A. Calvi, A. Parravicini, E. Rojatti, C. Viviani
    CNAO Foundation, Milan, Italy
 
  CNAO in Pavia is one of the first centers for hadrontherapy in Europe, treating patients since 2011. The center is an international reference for a whole new concept of machines being constructed for this purpose. The synchrotron BPM electronics is based on analog boards that compute the ratio between difference and sum signals from the shoebox pickup, later acquired by digital cards. Although the system operates reliably, it just calculates the position with 1kHz rate, while the revolution frequency ranges from 0.5 to 3 MHz. To extend the measurement possibilities for these new hadron synchrotrons, Instrumentation Technologies is developing a data acquisition system capable of acquiring the pickup signals with 125MSps ADCs and calculating bunchbybunch positions of the accelerated beam. The first prototype was tested at CNAO: the turnbyturn beam position was analyzed off line, at different energies and positions with both Protons and Carbon ions beam. This paper will presents the results achieved with the system and compares them with the measurements of the current system.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF024  
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WEPAF025 Fast Intensity Monitor Based on Channeltron Electron Multiplier electronics, proton, high-voltage, detector 1873
 
  • G.M.A. Calvi, V. Lante, L. Lanzavecchia, G. Magro, A. Parravicini, E. Rojatti, C. Viviani
    CNAO Foundation, Milan, Italy
 
  The paper concerns the Fast Intensity Monitor (FIM) designed for the CNAO (Centro Nazionale di Adroterapia Oncologica), the Italian facility of Oncological Hadrontherapy. The FIM detector has been designed with the purpose of having a continuous and non-destructive measurement of the beam intensity in the High Energy Beam Transfer (HEBT) line. The passage of the beam through a thin aluminum foil produces secondary electrons whose yield depends on beam species (protons or carbon ions), intensity and energy. Secondary electrons are focused on the Channeltron Electron Multiplier (CEM) input, multiplied and sensed over a precision resistor. In order to minimize the perturbation to the beam, the foil is grounded and the read out electronics is floating. This makes electronics design harder but it is a key point to make FIM use possible continuously even during patients treatment. Measurements performed with the FIM are discussed and checked against reference detectors.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF025  
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WEPAF026 Beam Induced Fluorescence Measurements of 100 keV Deuterons in LIPAc Accelerator injection, detector, plasma, emittance 1877
 
  • R. Varela, A. Guirao, L.M. Martínez, J. Mollá, I. Podadera
    CIEMAT, Madrid, Spain
  • T. Akagi, R. Ichimiya, Y. Ikeda, M. Sugimoto
    QST, Aomori, Japan
  • B. Bolzon, N. Chauvin
    CEA/IRFU, Gif-sur-Yvette, France
  • P. Cara
    Fusion for Energy, Garching, Germany
  • H. Dzitko
    F4E, Germany
  • J. Knaster
    IFMIF/EVEDA, Rokkasho, Japan
 
  Funding: Work partially supported by the Spanish Ministry of Science and Innovation under project FIS2013-40860-R
The LIPAc accelerator will be a linear CW deuteron accelerator capable of delivering a 9 MeV, 125 mA beam which aims to validate the technology that will be used in the future high power accelerator-driven neutron source, IFMIF. In summer 2017 a campaign of measurements was done during the injector commissioning, in which a Fluorescence Profile Monitor based on an Intensified CID camera (ICID) was used to measure the beam transverse profile at the extraction of the ion source. In this contribution we review the design of the ICID, its performance and discuss the measurements carried out. The performance of ICID monitors for its use in future accelerators will be assessed.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF026  
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WEPAF027 Low Q Cavity BPM Study for the Beam Position Measurement of Nanosecond Spaced Electron Bunches cavity, FEL, dipole, coupling 1881
 
  • L. Yang, X. He, L.W. Zhang
    CAEP/IFP, Mainyang, Sichuan, People's Republic of China
  • S.S. Cao, Y.B. Leng, L.Y. Yu, R.X. Yuan
    SINAP, Shanghai, People's Republic of China
 
  Funding: National natural science foundation of China, 11705184
Low Q cavity BPM is a key to distinguish closely spaced electron bunches allowing precise beam handling for XFEL facilities operating in a multi-bunch mode at high repetition rate up to hundreds MHz. The inter-bunch signal pollution issue becomes significant when bunch separation is down to nanosecond and causes the position detection to be increasingly overestimated. Solely relying on extreme low Q to achieve sufficient decay within bunch interval leads to appreciable interference from non-signal modes due to strong overcoupling of antenna design is required. The error imposed on measured position raises a challenge to meet the goal of high resolution. Alternatively, a concept is proposed to remove the dominant part of signal pollution at the moment of sampling by intentionally shifting the phase of the last bunch signal 90degree respect to that of current bunch signal, where signal sampling is normally taken for nanosecond spaced bunches. This quadrature phase shift is defined by properly choosing the operational frequency of dipole mode regarding to the bunch frequency. A low Q cavity BPM prototype to identify technical challenges and verify this concept is under development in the R&D plan for future XFEL with high repetition rate
 
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WEPAF034 A Supersonic Gas Jet-Based Beam Profile Monitor Using Fluorescence for HL-LHC photon, luminosity, gun, hadron 1891
 
  • H.D. Zhang, A.S. Alexandrova, R. Schnuerer, C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • M. Ady, E. Barrios Diaz, N. Chritin, O.R. Jones, R. Kersevan, T. Marriott-Dodington, S. Mazzoni, A. Rossi, G. Schneider, R. Veness
    CERN, Geneva, Switzerland
  • A.S. Alexandrova, A. Salehilashkajani, R. Schnuerer, C.P. Welsch, H.D. Zhang
    The University of Liverpool, Liverpool, United Kingdom
  • P. Forck, S. Udrea
    GSI, Darmstadt, Germany
  • P. Smakulski
    WRUT, Wroclaw, Poland
 
  Funding: The HL-LHC project, the Helmholtz Association under contract VH-NG-328, the EU's 7th Framework Programme under grant agreement no 215080 and the STFC Cockcroft core grant No. ST/G008248/1.
The High-Luminosity Large Hadron Collider (HL-LHC) project aims to increase the machine luminosity by a factor of 10 as compared to the LHC's design value. To achieve this goal, a special type of electron lens is being developed. It uses a hollow electron beam which co-propagates with the hadron beam to act on any halo particles without perturbing the core of the beam. The overlapping of both beams should be carefully monitored. This contribution presents the design principle and detailed characteristics of a new supersonic gas jet-based beam profile monitor. In contrast to earlier monitors, it relies on fluorescence light emitted by the gas molecules in the jet following interaction with the primary hadron beams. A dedicated prototype has been designed and built at the Cockcroft Institute and is being commissioned. Details about monitor integration, achievable resolution and dynamic range will be given.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF034  
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WEPAF036 Energy Independence in Optical Transition Radiation Imaging simulation, radiation, diagnostics, optics 1898
 
  • J. Wolfenden, R.B. Fiorito, C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • R.B. Fiorito, C.P. Welsch, J. Wolfenden
    The University of Liverpool, Liverpool, United Kingdom
 
  Funding: This work was supported by the EU under Grant Agreement No. 624890 and the STFC Cockcroft Institute core Grant No. ST/G008248/1.
The exploitation of optical transition radiation (OTR) in imaging-based diagnostics for charged particle beams is a well-established technique. Simulations of the expected OTR transverse beam profiles are therefore important in both the design of such imaging systems and the analysis of the data. Simulating OTR images is relatively straightforward for low energy electron beams. However, in the near future electron machines will be using high-energy and low-emittance beams. Using such parameters can be challenging to simulate, and can be limiting in their account of practical factors, e.g. chromatic aberrations. In this work we show systematically that the use of low-energy parameters in high-energy OTR image simulations induces little deviation in the resulting transverse beam profiles. Simulations therefore become much easier to perform, and further analysis may be performed. This opens up exciting opportunities to perform simulations quicker and with reduced demands on the computation requirements. It will be shown in this contribution how this approach will enable enhanced ways to optimize OTR diagnostics.
 
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WEPAF041 Use of Dimension-Reduction Techniques With Multi-Objective Genetic Algorithms to Improve the Vertical Emittance and Orbit at CESR emittance, storage-ring, simulation, lattice 1901
 
  • W.F. Bergan, I.V. Bazarov, C.J. Duncan, D. L. Rubin
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • D. Liarte, J.P. Sethna
    Cornell University, Ithaca, New York, USA
 
  Funding: DOE DE-SC0013571 NSF DGE-1650441
In order to reduce the vertical emittance at the Cornell Electron Storage Ring (CESR), we first measure and correct the vertical orbit, dispersion, and coupling. However, due to the finite resolution of our optics measurements, we still retain a significant residual emittance. In order to correct this further, we made use of the theory of sloppy models, according to which certain high-dimensionality systems can be modeled with significantly fewer "eigenparameters" that still contain most of the effect on the desired objective, in this case, the emittance.* However, we noted that using these knobs for tuning often resulted in increased vertical orbit errors. In an attempt to constrain these, we have applied multi-objective genetic algorithms to this problem. We have found that it can be more efficient to run such algorithms using our eigenparameters as the genes to be varied, as opposed to the raw magnet values. When running with the first 8 such knobs as genes, we can get either orbits or beam sizes as good as we obtain with our regular emittance-tuning algorithm which uses all the corrector magnets.
*K.S. Brown and J.P. Sethna, Phys. Rev. E 68, 021904 (2003).
 
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WEPAF043 Commissioning and Long-Term Results of a Fully-Automated Pulse-Based Optical Timing Distribution System at Dalian Coherent Light Source timing, laser, operation, detector 1909
 
  • H.P.H. Cheng, A. Berlin, E. Cano, A. Dai, J. Derksen, D. Forouher, W. Nasimzada, M. Neuhaus, P. Schiepel, E. Seibel, K. Shafak
    Cycle GmbH, Hamburg, Germany
  • Z. Chen, H.L. Ding, Z.G. He, Y.H. Tian, G.R. Wu
    DICP, Dalian, People's Republic of China
  • F.X. Kärtner
    Deutsches Elektronen Synchrotron (DESY) and Center for Free Electron Science (CFEL), Hamburg, Germany
  • B. Liu, X.Q. Liu
    SINAP, Shanghai, People's Republic of China
 
  New generation light sources such as X-ray free-electron lasers* and attoscience centers** require high demand for timing synchronization, on the order of few femtoseconds or below, to generate ultrashort X-ray pulses that enables attosecond temporal and subatomic spatial resolution. The challenge in achieving this scientific dream lies in part in a reliable, high-precision timing distribution system that can synchronize various optical and microwave sources across multi-km distances with good long-term stability. It was shown that the pulsed-optical timing distribution system can deliver sub-fs long-term timing precision between remotely synchronized lasers and microwave sources in laboratory environment.*** We present the latest results from the commissioning of China's first multi-link pulse-based optical timing distribution system (TDS) installed at Dalian Coherent Light Source. Long term operating results of the fully-automated polarization-maintaining TDS, as well as lessons learned and recommendations for future improvements, are presented, including performance of the timing-stabilized PM fiber links, microwave end-stations and ultrafast laser synchronization end-stations.
*http://www.xfel.eu/news/2017/europeanxfelgeneratesitsfirstlaserlight
**G. Mourou and T. Tajima, Science, 331, pp. 41-42, 2011.
***M. Xin et al., Light Sci. Appl., 6, e16187, 2017.
 
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WEPAF046 RF Electronics for the Measurement of Beam Induced Higher Order Modes (HOM) Implemented in the MicroTCA.4 Form Factor HOM, cavity, dipole, electronics 1916
 
  • S. Jabłoński, N. Baboi, U. Mavrič, H. Schlarb
    DESY, Hamburg, Germany
 
  Higher order modes (HOM) excited in RF accelerating cavities by a particle beam can be used for electron beam diagnostics. Phase of a monopole HOM provides information about the beam phase relative to the externally induced RF field in a cavity (BPhM) [1]. Furthermore, the amplitude of a dipole mode is proportional to the beam position in the cavity, hence it can be used for beam position monitoring (BPM). In this paper we present a prototype of an instrument implemented in the MicoTCA.4 form factor for the measurement of the HOMs at FLASH and Eu-XFEL. The prototype consists of an analog module, which is used for filtering and conditioning of the selected modes, and a digital module responsible for digitization and signal processing. We present the instruments performance and discuss its influence on the precision of the HOM-based diagnostics.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF046  
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WEPAF048 High Resolution and Low Charge Button and Strip-Line Beam Position Monitor Electronics Upgrade at Flash electronics, FEL, laser, operation 1923
 
  • B. Lorbeer, N. Baboi, H.T. Duhme, Re. Neumann
    DESY, Hamburg, Germany
 
  Historically the FLASH (Free Electron Laser in Hamburg) facility at DESY (Deutsches Elektronen-Synchrotron) in Germany has foreseen operation in a charge range from 1nC-3nC for which a VME based BPM(Beam Position Monitor) system has been in operation since 2005. For a couple of years the standard machine operation has been settled at a few hundreds of pC with the tendency for smaller charges down to 100pC and smaller. The availability and resolution performance of the BPM system at charges below 300pC in many locations along the machine was unsatisfactory. In the last couple of years a new BPM electronic system based on the utca standard has been developed to overcome these limitations. A substantially improved version of the analog frontend and digital electronics has been developed in 2016 and tested successfully. During shutdown works at FLASH in summer 2017 all old button and strip-line BPM electronics has been replaced with the new type of electronics. This paper summarizes the features and performance of the new BPM system, compares the beam jitter free resolution of old and new BPM system and highlights its high single shot resolution of better than 10um at a charge of 15pC.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF048  
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WEPAF049 Energy Beam Position Monitor Button Array Electronics for the European XFEL FEL, vacuum, electronics, pick-up 1927
 
  • B. Lorbeer, B. Beutner, H.T. Duhme, L. Fröhlich, D. Lipka, D. Nölle
    DESY, Hamburg, Germany
 
  The European XFEL(X-Ray Free Electron Laser) at DESY(Deutsches Elektronen-Synchrotron) in Hamburg/Schenefeld started commissioning in early 2017. Before the pulsed electron beam is accelerated to its final energy of 14 GeV, the energy of the bunch can be compressed in three bunch compression chicanes at 130 MeV, 700 MeV and 2400 MeV. The vacuum chamber in these sections is tapered from 40 mm round beam pipe to a 40 cm rectangular shaped vacuum section. A custom made button array type of BPM(Beam position Monitor) is installed in this section with 26 button electrode feed-throughs. The analog and digital readout electronics for this monitor and the first experience with the calibration and operational aspects of this system are presented in this poster.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF049  
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WEPAF050 Simulations of 3D Charge Density Measurements for Commissioning of the PolariX-TDS cavity, simulation, MMI, lattice 1930
 
  • D. Marx, R.W. Aßmann, R.T.P. D'Arcy, B. Marchetti
    DESY, Hamburg, Germany
 
  The prototype of a novel X-band transverse deflection structure, the Polarizable X-band (PolariX) TDS*, is currently being prepared for installation in the FLASHForward beamline** at DESY in early 2019. This structure will have the novel feature of variable polarization of the deflecting mode, allowing bunches to be streaked at any transverse angle, rather than at just one angle as in a conventional cavity. By combining screen profiles from several streaking angles using tomographic reconstruction techniques, the full 3D charge density of a bunch can be obtained***. It is planned to perform this measurement for the first time during commissioning of the structure. In this paper, simulations of this measurement are presented and the effects of jitter are discussed.
*P Craievich et al. paper THPAL068, this conference
**A Aschikhin et al. Nucl. Instr. Meth. Phys. Res. A., vol.806, pp.175-183, 2018
***D Marx et al. J. Phys.: Conf. Ser., vol.874, p.012077, 2017
 
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WEPAF051 LLRF Operation and Performance at the European XFEL LLRF, FEL, operation, MMI 1934
 
  • M. Omet, V. Ayvazyan, J. Branlard, L. Butkowski, M. Hierholzer, M. Killenberg, D. Kostin, L. Lilje, S. Pfeiffer, H. Schlarb, Ch. Schmidt, V. Vogel, N. Walker
    DESY, Hamburg, Germany
 
  The European X-ray Free-Electron Laser (XFEL) at Deutsches Elektronen-Synchrotron (DESY), Hamburg, Germany is a user facility providing ultrashort hard and soft X-ray flashes with a high brilliance. All LLRF stations of the injector, covering the normal conducting RF gun, A1 (8 1.3 GHz superconducting cavities (SCs)) and AH1 (8 3.9 GHz SCs), were successfully commissioned by the end of 2015. The commissioning of LLRF stations A2 to A23 (32 1.3 GHz SCs each) in the XFEL accelerator tunnel (XTL) was concluded in June 2017. SASE light was produced in SASE undulator section SA1 and delivered to the first users in September 2017, marking the beginning of regular user operation. The current state of the LLRF systems, the experience gained during operation and the performance achieved in terms of stability and energy reach are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF051  
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WEPAF053 Status and Commissioning of the European XFEL Beam Loss Monitor System FEL, high-voltage, controls, hardware 1940
 
  • T. Wamsat, T. Lensch, P.A. Smirnov
    DESY, Hamburg, Germany
 
  The European XFEL MTCA based Beam Loss Monitor System (BLM) is composed of about 450 monitors, which are part of the Machine Protection System (MPS). The BLMs detect losses of the electron beam, in order to protect accelerator components from damage and excessive activation, in particular the undulators, since they are made of permanent magnets. Also each cold accelerating module is equipped with a BLM to measure the sudden onset of field emission (dark current) in cavities. In addition some BLMs are used as detectors for wire- scanners. Experience from the already running BLM system in FLASH2 which is based on the same technology, led to a fast implementation of the system in the XFEL. Further firmware and server developments related to alarm generation and handling are ongoing. The BLM systems structure, the current status and the different possibilities to trigger alarms which stop the electron beam will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF053  
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WEPAF057 Electron Beam Diagnostics Concept for the ELI LUX Project diagnostics, laser, undulator, plasma 1954
 
  • K.O. Kruchinin, D. Kocon, A.Y. Molodozhentsev, L. Pribyl
    ELI-BEAMS, Prague, Czech Republic
  • A. Lyapin
    JAI, Egham, Surrey, United Kingdom
 
  Nowadays the popularity of Laser Wakefield Accelerators (LWFA) is increasingly growing. Although the quality of the beams produced by LWFA is still lower than provided by conventional accelerators, they have great potential to be considered as a new basis for future FELs and even colliders. Laser Undulator X-ray (LUX) source is being commissioned at ELI-beamlines in Czech Republic. The goal of this machine is to provide photon beam in so called "water window" wavelength region for user experiments. Possible upgrade of the facility towards the LWFA based FEL is also considered. The electron beam diagnostics is absolutely crucial for achieving the aim of LUX. Specific properties of the beam produced by current LWFA, such as low charge, poor beam stability, big beam divergence and energy spread, require rethinking and adaptation of the conventional diagnostic tools and, in some cases, development of new ones. Ideally, they have to be compact, stable, non-invasive and allow measurements in single-shot mode. In this report we will present an overview and design considerations for the LUX electron beam main diagnostics. We will also discuss the hardware status and future plans.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF057  
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WEPAF059 A Low Cost Beam Position Monitor System pick-up, electronics, hardware, target 1961
 
  • C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • J.G. Power, J.H. Shao
    ANL, Argonne, Illinois, USA
  • C. Yin
    University of Chicago, Chicago, Illinois, USA
 
  A Beam Position Monitor (BPM) system is essential to beam diagnostics for almost all particle accelerators. However, a typical BPM system contains customized hardware and complicated processing electronics which considerably drive the cost for large facilities where hundreds of them may be used. It also limits its use in the small scale accelerator facilities. In the paper, we present a low cost BPM system which consists of a commercial available CF flange based signal pickup device, a low cost integrated circuit adjacent to the pickup to filter, sample, digitize, and broadcast the signals out of the pickup electrodes. The digital signal is transmitted out for post processing through noise-protected Wi-Fi router. We will briefly discuss the working principle and experimental progress to date.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF059  
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WEPAF060 Non-Invasive Bunch Length Diagnostics for High Intensity Beams detector, radiation, real-time, simulation 1964
 
  • S.V. Kuzikov, S.P. Antipov
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • S.V. Kuzikov, A.A. Vikharev
    IAP/RAS, Nizhny Novgorod, Russia
 
  Modern particle accelerators utilize photoinjectors and compression schemes to produce short high peak current electron bunches for various applications like x-ray free electron lasers, high gradient beam driven acceleration and others. Bunch length detection is a desired diagnostics for such machines. In this paper we describe a non-invasive, real-time detector which can be retrofitted into an existing beamline and measure the bunch length in real time using interferometric methods. Diffraction radiation is the mechanism to be used to produce a measurable signal without intercepting the beam. This became possible as sensitivity of pyrodetectors improved over the years, while peak beam power grew. For high peak current beams there is a possibility of a single shot measurement. This can be done with a pair of closely placed vacuum breaks that create a spatial correlation of the generated signals which can be measured by a pyro-detector array or a THz camera. The bunch length is determined from the correlation data using an iterative beam profile recovery algorithm.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF060  
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WEPAF070 Commissioning of Beam Instrumentation at the CERN AWAKE Facility After Integration of the Electron Beam Line proton, plasma, laser, experiment 1993
 
  • I. Gorgisyan, C. Bracco, S. Burger, S. Döbert, S.J. Gessner, E. Gschwendtner, L.K. Jensen, S. Jensen, S. Mazzoni, D. Medina, K. Pepitone, L. Søby, F.M. Velotti, M. Wendt
    CERN, Geneva, Switzerland
  • M. Cascella, S. Jolly, F. Keeble, M. Wing
    UCL, London, United Kingdom
  • V.A. Verzilov
    TRIUMF, Vancouver, Canada
 
  The Advanced Proton Driven Plasma Wakefield Acceleration Experiment (AWAKE) is a project at CERN aiming to accelerate an electron bunch in a plasma wakefield driven by a proton bunch*. The plasma is induced in a 10 m long Rubidium vapour cell using a pulsed Ti:Sapphire laser, with the wakefield formed by a proton bunch from the CERN SPS. A 16 MeV electron bunch is simultaneously injected into the plasma cell to be accelerated by the wakefield to energies in GeV range over this short distance. After successful runs with the proton and laser beams, the electron beam line was installed and commissioned at the end of 2017 to produce and inject a suitable electron bunch into the plasma cell. To achieve the goals of the experiment, it is important to have reliable beam instrumentation measuring the various parameters of the proton, electron and laser beams such as transverse position, transverse profile as well as temporal synchronization. This contribution presents the status of the beam instrumentation in AWAKE, including the new instruments incorporated into the system for measurements with the electron beam line, and reports on the performance achieved during the AWAKE runs in 2017.
* Gschwendtner E., et al. "AWAKE, the Advanced Proton Driven Plasma Wakefield Experiment at CERN", NIM A 829 (2016)76-82
 
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WEPAF074 Non-invasive Beam Diagnostics with Cherenkov Diffraction Radiation photon, radiation, detector, plasma 2005
 
  • T. Lefèvre, M. Bergamaschi, O.R. Jones, R. Kieffer, S. Mazzoni
    CERN, Geneva, Switzerland
  • L.Y. Bartnik, M.G. Billing, Y.B.P. Bordlemay Padilla, J.V. Conway, M.J. Forster, J.P. Shanks, S. Wang
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • M. Bergamaschi, P. Karataev
    Royal Holloway, University of London, Surrey, United Kingdom
  • V.V. Bleko, A.S. Konkov, J.S. Markova, A. Potylitsyn
    TPU, Tomsk, Russia
  • L. Bobb
    DLS, Oxfordshire, United Kingdom
  • K. Lekomtsev
    JAI, Egham, Surrey, United Kingdom
 
  Based on recent measurements of incoherent Cherenkov Diffraction Radiation (ChDR) performed on the Cornell Electron Storage Ring, we present here a concept for the centering of charged particle beams when passing close to dielectric material. This would find applications as beam instrumentation in dielectric capillary tubes, typically used in novel accelerating technologies, as well as in collimators using bent crystals for high-energy, high-intensity hadron beams, such as the Large Hadron Collid-er or Future Circular Collider. As a charged particle beam travels at a distance of a few mm or less from the surface of a dielectric material, incoherent ChDR is produced inside the dielectric. The photons are emitted at a large and well-defined angle that allows their detection with a limited contribution of background light. A set of ChDR detectors distributed around a dielectric would enable both the beam position and tilt angle to be measured with a good resolution.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF074  
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WEPAF084 Commissioning the ELENA Beam Diagnostics Systems at CERN proton, diagnostics, MMI, antiproton 2043
 
  • G. Tranquille, S. Burger, M. Gąsior, P. Grandemange, T.E. Levens, O. Marqversen, L. Søby
    CERN, Geneva, Switzerland
 
  The Extra Low ENergy Antiproton ring (ELENA) at CERN entered the commissioning phase in November 2016 using H ions and antiprotons to setup the machine at the different energy plateaus. The low intensities and energy of the ELENA beam generate very weak signals making beam diagnostics very challenging. With a circulating beam current of less than 1 μA and an energy where the beam annihilates in less than a few microns of matter, special care was taken during the design phase to ensure an optimal performance of these measurement devices once installed on the ring and transfer lines. A year on we present the performance of the various devices that have been deployed to measure the beam parameters from the extraction point of the Antiproton Decelerator (AD), through the ELENA ring and in the experimental lines.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF084  
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WEPAF085 Upgrade of the CERN SPS Beam Position Measurement System electronics, pick-up, proton, FPGA 2047
 
  • M. Wendt, M. Barros Marin, A. Boccardi, T.B. Bogey, V. Kain, C. Moran Guizan, A. Topaloudis
    CERN, Geneva, Switzerland
  • I. Degl'Innocenti
    Università di Pisa, Pisa, Italy
 
  The CERN Super Proton Synchrotron (SPS) is a fast cycling hadron accelerator delivering protons with momenta of up to 450 GeV/c for the Large Hadron Collider (LHC), fixed target experiments and other users such as the AWAKE plasma acceleration experiment, and also used to accelerate heavy ions. This paper presents the upgrade initiative for the SPS beam position measurement system in the frame of the CERN LHC Injector Upgrade (LIU) project. The new SPS beam position read-out electronics will be based on logarithmic amplifiers, using signals provided by the 216 existing beam position monitors, the majority of which are based on split-plane 'shoebox' technology. It will need to cover a dynamic range sufficient to manage the wide range of SPS beam intensities and bunch formatting schemes to provide turn-by-turn and averaged beam orbits along the SPS acceleration cycles. In order to avoid long coaxial cables, the front-end electronics including the digitisation, will be located inside the accelerator tunnel, with optical transmission to surface processing electronics. This represents an additional challenge in terms of radiation tolerance of electronics components and materials.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF085  
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WEPAF087 The First Experience and Results of Beam Diagnostics Deployment at the ESS Accelerator ion-source, MMI, diagnostics, emittance 2054
 
  • V. Grishin, E.C. Bergman, B. Cheymol, C.S. Derrez, T.J. Grandsaert, H. Hassanzadegan, A. Jansson, H. Kocevar, O. Midttun, S. Molloy, J. Norin, T.J. Shea, C.A. Thomas
    ESS, Lund, Sweden
  • W. Ledda
    Vitrociset s.p.a, Roma, Italy
  • F. Senée, O. Tuske
    CEA/IRFU, Gif-sur-Yvette, France
 
  The European Spallation Source (ESS) will produce neutrons for science by subjecting a tungsten target to the high-intensity proton beam from a superconducting linear accelerator. A complete suite of beam diagnostics will enable tuning, monitoring and protection of the accelerator during commissioning, studies and operation. As an initial step toward neutron production, the Ion Source and the 75 keV Low Energy Transport Line is installed on the ESS site in Lund, Sweden. To support the commissioning and characterization of this first beam-producing system, a subset of the full diagnostics suite is deployed. This includes the following equipment: a faraday cup, current transformers, an emittance measurement unit, beam-induced fluorescence monitors, and a doppler-shift spectroscopy system. All aspects of the deployment experience, from acceptance testing through installation, verification, and commissioning will be presented.
*Beam Instrumentation
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF087  
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WEPAF088 Machine Protection Features of the ESS Beam Current Monitor System machine-protect, electronics, interface, ion-source 2058
 
  • H. Hassanzadegan, E. Bargalló, S.G. Gabourin, T. Korhonen, S. Kövecses de Carvalho, A. Nordt, T.J. Shea
    ESS, Lund, Sweden
  • M. Mohammednezhad
    Sigma Connectivity Engineering, Lund, Sweden
  • M. Werner
    DESY, Hamburg, Germany
 
  The BCM system of the European Spallation Source includes several machine protection features to ensure that the actual beam parameters will be consistent with the selected beam and destination modes. Differential current measurements with several ACCT pairs are foreseen to detect beam losses particularly in the low-energy linac where Beam Loss Monitors cannot be used. The ACCTs will also be used to check that no beam will be present in the sections downstream of a temporary beam dump. These measurements will then be used to stop the beam shortly after an abnormal condition has been detected by the BCM system. This will require some customized interfaces with the Timing System and the Machine Protection System as well as an optical interface for differential current measurement over large distances. Automatic setting of the machine protection thresholds and masking/unmasking of the interlocks based on the beam and destination modes are among the technical complexities. This paper gives an overview of the design including the most recent updates and discusses in more details the machine protection features of the BCM system.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF088  
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WEPAG005 Synchrotron Radiation Beam Diagnostics for the Integrable Optics Test Accelerator controls, optics, synchrotron, proton 2073
 
  • N. Kuklev, Y.K. Kim
    University of Chicago, Chicago, Illinois, USA
  • A.L. Romanov
    Fermilab, Batavia, Illinois, USA
 
  Funding: Work supported by the U.S. National Science Foundation under Award PHY-1535639. Fermi Research Alliance, LLC operates Fermilab under Contract DE-AC02-07CH11359 with the US Department of Energy.
The Integrable Optics Test Accelerator (IOTA) is a research electron and proton storage ring currently being commissioned at Fermilab's Accelerator Science and Technology (FAST) facility. An extensive beam physics research program is planned, including tests of novel techniques for improving beam intensity, stability, and emittance. A key part of IOTA beam diagnostics suite are synchrotron light beam monitors, mounted onto each dipole. In this paper, we present the hardware and software design of this system. Mechanical layout and actuator control electronics are described. High throughput image acquisition and analysis architecture is outlined, and its preliminary performance is explored. Integration of the system within accelerator control network and possible user applications, such as camera auto-focusing, are discussed.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAG005  
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WEPAK008 Reconstructing Space-Charge Distorted IPM Profiles with Machine Learning Algorithms simulation, space-charge, GUI, network 2099
 
  • D.M. Vilsmeier, M. Sapinski, R. Singh
    GSI, Darmstadt, Germany
  • J.W. Storey
    CERN, Geneva, Switzerland
 
  Measurements of undistorted transverse profiles via Ionization Profile Monitors (IPMs) may pose a great challenge for high brightness or high energy beams due to interaction of ionized electrons or ions with the electromagnetic field of the beam. This contribution presents application of various machine learning algorithms to the problem of reconstructing the actual beam profile from measured profiles that are distorted by beam space-charge interaction. (Generalized) linear regression, artificial neural network and support vector machine algorithms are trained with simulation data, obtained from the Virtual-IPM simulation tool, in order to learn the relation between distorted profiles and original beam dimension. The performance of different algorithms is assessed and the obtained results are very promising for testing with simulation data.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAK008  
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WEPAK009 Applications of the Interferometric Beam Size Monitor at BESSY II storage-ring, diagnostics, operation, photon 2103
 
  • M. Koopmans, P. Goslawski, J.G. Hwang, A. Jankowiak, M. Ries, A. Schälicke, G. Schiwietz
    HZB, Berlin, Germany
 
  For the upgrade project of the BESSY~II storage ring to BESSY~VSR * an interferometric beam size monitor was designed and set up. Since this system uses visible light it can be upgraded efficiently to provide bunch resolved measurements. These are required for machine commissioning, development and to ensure long term quality and stability of user operation of BESSY~VSR. Various applications of the system are outlined and measurements are presented.
* A. Jankowiak et al., eds., BESSY VSR Technical Design Study, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Germany, June 2015. DOI: 10.5442/R0001
 
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WEPAK011 Development of the Electron-Beam Diagnostics for the Future BESSY-VSR Storage Ring diagnostics, laser, dipole, storage-ring 2110
 
  • G. Schiwietz, J.G. Hwang, M. Koopmans, M. Ries, A. Schälicke
    HZB, Berlin, Germany
 
  This contribution focusses on the different types of new or improved electron-beam monitors at BESSY II for bunch resolved measurements under future BESSY-VSR conditions. A new diagnostics platform, involving three different dipole beam lines will be built for different di-pole-related optical and THz methods. Our main concepts for robust future monitors for bunch length, beam size and position are presented in the following.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAK011  
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WEPAL005 Beam Size Measurement and PSF Evaluate of KB Mirror Monitor at SSRF SRF, storage-ring, optics, photon 2151
 
  • D.C. Zhu, J.S. Cao, Y.F. Sui, J.H. Yue
    IHEP, Beijing, People's Republic of China
 
  Funding: Work supported by National Nature Science Foundation of China(11605213)
A Kirkpatrick Baez mirror imaging system was designed and installed to measure the transverse beam size and emittance of SSRF storage ring. Two crossed cylindrical mirrors are used to image the dipole source point in the horizontal and vertical direction. Both mirrors could be moved in and out in order to interchangeable with an original X-ray pinhole system. Hard X-ray with peak energy of 20.5 keV was focused at the X-ray scintillator camera. Aberration and point spread function which would cause image blur were evaluated. System commissioning and optimization have been done. PSF measurement was acquired using beam based calibration scheme by varying the beam images with different quadrupole settings and fitting them with the corresponding theoretical beam sizes.
 
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WEPAL010 Review of the ELI-NP-GBS Low Level RF and Synchronization Systems LLRF, laser, linac, timing 2162
 
  • L. Piersanti, D. Alesini, M. Bellaveglia, F. Cardelli, M. Diomede, A. Gallo, V. Martinelli
    INFN/LNF, Frascati (Roma), Italy
  • B.B. Baricevic, R. Cerne, G. Jug
    I-Tech, Solkan, Slovenia
  • M. Diomede
    Sapienza University of Rome, Rome, Italy
  • P.N. Dominguez
    Menlo Systems GmbH, Martinsried, Germany
 
  ELI-NP is a linac based gamma-source in construction at Magurele (RO) by the European consortium EuroGammaS led by INFN. Photons with tunable energy and with intensity and brilliance well beyond the state of the art, will be produced by Compton back-scattering between a high quality electron beam (up to 740 MeV) and a 515 nm intense laser pulse. Production of very intense photon flux with narrow bandwidth requires multi-bunch operation at 100 Hz repetition rate. A total of 13 klystrons, 3 S-band (2856 MHz) and 10 C-band (5712 MHz) will power a total of 14 Travelling Wave accelerating sections (2 S-band and 12 C-band) plus 3 S-band Standing Wave cavities (a 1.6 cell RF gun and 2 RF deflectors). Each klystron is individually driven by a temperature stabilized LLRF module for a maximum flexibility in terms of accelerating gradient, arbitrary pulse shaping (e.g. to compensate beam loading effects in multi-bunch regime) and compensation of long-term thermal drifts. In this paper, the whole LLRF system architecture and bench test results, the RF reference generation and distribution together with an overview of the synchronization system will be described.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL010  
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WEPAL012 Measurements with the ELI-NP Cavity Beam Position Monitor Read-out Electronics at FLASH cavity, instrumentation, electronics, FEL 2169
 
  • G. Franzini, D. Pellegrini, M. Serio, A. Stella, A. Variola
    INFN/LNF, Frascati (Roma), Italy
  • B.B. Baricevic, M. Cargnelutti
    I-Tech, Solkan, Slovenia
  • D. Lipka
    DESY, Hamburg, Germany
  • M. Marongiu
    INFN-Roma, Roma, Italy
  • A. Mostacci
    Sapienza University of Rome, Rome, Italy
 
  The Extreme Light Infrastructure - Nuclear Physics Gamma Beam Source (ELI-NP GBS) will be installed and commissioned starting within the next year in Magurele, Romania. It will generate gamma beam through Compton back-scattering of a recirculated laser and a multi-bunch electron beam, produced by a 720 MeV LINAC. In order to obtain bunch by bunch position measurements, four cavity beam position monitors (cBPM) near the two interaction points are foreseen. Extensive tests on the cBPM read-out electronics, recently developed by Instrumentation Technologies and acquired for ELI-NP GBS, were performed in laboratory at INFN-LNF and at FLASH in DESY, during the user operation. In the latter case, three cBPMs installed along the LINAC, with similar features as the ones of ELI-NP GBS, were used as measuring devices and signal sources for the read-out electronics under test. We present here the measurements collected and the related analysis, with a particular focus on the beam position measurement resolution.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL012  
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WEPAL013 Design of the Diagnostic Stations for the ELI-NP Compton Gamma Source radiation, optics, linac, simulation 2173
 
  • M. Marongiu
    INFN-Roma, Roma, Italy
  • M. Castellano, E. Chiadroni, G. Di Pirro, G. Franzini, A. Giribono, V. Shpakov, A. Stella, A. Variola
    INFN/LNF, Frascati (Roma), Italy
  • A. Cianchi
    Università di Roma II Tor Vergata, Roma, Italy
  • A. Mostacci, L. Palumbo
    Sapienza University of Rome, Rome, Italy
 
  A high brightness electron Linac is being built in the Compton Gamma Source at the ELI Nuclear Physics facility in Romania. To achieve the design luminosity, a train of 32 bunches, 16 ns spaced, with a nominal charge of 250 pC will collide with the laser beam in the interaction point. Electron beam spot size is measured with optical transition radiation (OTR) profile monitors. Furthermore, OTR angular distribution strongly depends on beam energy. Since OTR screens are typically placed in several positions along the Linac to monitor beam envelope, one may perform a distributed energy measurement along the machine. This will be useful, for instance, during the commissioning phase of the GBS in order to verify the correct functionality of the C-Band accelerating structures, due to the fact that there are OTR screens after each accelerating module. This paper deals with the studies of different optic configurations to achieve the field of view, resolution and accuracy in order to measure the energy of the beam. Several configurations of the optical detection line will be studied with simulation tools (e.g. Zemax).  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL013  
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WEPAL014 Non-Distructive 2-D Beam Profile Monitor Using Gas Sheet in J-PARC LINAC linac, injection, vacuum, cavity 2177
 
  • J. Kamiya, Y. Hikichi, M. Kinsho, A. Miura, N. Ogiwara
    JAEA/J-PARC, Tokai-mura, Japan
 
  We have been developed a beam profile monitor using interaction between the beam and the gas molecules distributed in sheet shape*. Generated luminescence or ions by passing the beam through the gas sheet has the information of cross-section shape of the beam. The gas sheet beam monitor will become a useful tool to measure the profile of high power beams because it has no breakable element such as wires and a 2-D beam profile at a certain position of beam line can be immediately obtained by just injecting the gas. Previously, the development of the gas sheet generator and successful demonstration of the beam profile measurement were reported. This time, we applied a gas sheet monitor to J-PARC LINAC, where the negative hydrogen atoms (H) are accelerated to the energy of 400 MeV in the normal operation. Most challenging factor was the development of the gas sheet monitor system, which generates the enough dense gas sheet to detect the clear image of the beam profile without harmful effect on the ultra-high vacuum in the beam line. We will report the gas sheet beam monitor system for J-PARC LINAC and the results of the first measurement of the beam profile.
* N. Ogiwara, et al., Proceedings of IPAC2016, p.2102.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL014  
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WEPAL016 Tensile Fracture Test of Metallic Wire of Beam Profile Monitors linac, cavity, beam-loading, controls 2183
 
  • A. Miura, Y. Kawane, K. Moriya
    JAEA/J-PARC, Tokai-mura, Japan
  • S. Fukuoka
    Nihon Koshuha Co. Ltd, Yokohama, Japan
  • K. Futatsukawa, T. Miyao
    KEK, Ibaraki, Japan
 
  In order to mitigate the beam loss during a beam transportation in a high-brilliant accelerator facilities, wire-based profile monitors are used to measure by both transverse and longitudinal beam profiles using wire-scanner monitors (WSMs) and bunch-shape monitors (BSMs) for the tuning of quadrupole magnets and bunching cavities. Signals are come from the direct interaction between a metallic wire and beam. We have used the tungsten wire as a high melting-point material by estimation of heat loading during the impact of beam particles. In addition, a spring is applied for the relaxing a sag under wire's own weight. A tensile fracture test is conducted by supplying an electrical current as a simulated beam-heat loading. As the results, we obtained the relation between the thermal limit to break down and tension loading of tungsten wire.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL016  
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WEPAL018 A Non-destructive 2D Profile Monitor Using a Gas Sheet experiment, proton, linac, target 2190
 
  • N. Ogiwara, Y. Namekawa
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • M. Fukuda, K. Hatanaka, T. Shima, K. Takahisa
    RCNP, Osaka, Japan
  • Y. Hikichi, J. Kamiya, M. Kinsho
    JAEA/J-PARC, Tokai-mura, Japan
  • Y. Hori
    KEK, Tokai, Ibaraki, Japan
 
  We are developing a non-destructive and fast-response beam profile monitor using a dense gas sheet target. To make a gas sheet, we use the beaming effect, which is well known in vacuum science and technology. The emitted molecules through a long rectangular channel, which has a very small ratio of the gap to the width, are forced to concentrate on a plane. The gas sheet with a thickness of 1.5 mm and the density of 2×10-4 Pa was easily generated by the combination of the deep slit and the thin slit. Here, the gas sheet was produced by the deep slit, and the shape of the sheet was improved by the thin slit. The usefulness of this monitor was shown by the following experiments: 1) For the electron beam of 30 keV with a diameter greater than 0.35 mm, the position and the two-dimensional profiles were well measured using the gas sheet. 2) Then the profiles of the 10 and 400 MeV proton beam with a current of several microamperes were well measured, too. 3) Recently, the profiles of the 400 MeV H ion beams in J-PARC linac were measured.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL018  
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WEPAL019 A Novel Field Cage Design for the CPS IPM and Systematic Errors in Beam Size and Emittance detector, cathode, extraction, emittance 2193
 
  • K. Satou
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • D. Bodart, S. Levasseur, G. Schneider, J.W. Storey
    CERN, Geneva, Switzerland
  • M. Sapinski
    GSI, Darmstadt, Germany
 
  An ionization profile monitor has been recently installed in the CERN proton synchrotron. We design a novel and simple structure field cage that suppresses the secondary electrons that are induced by the ionized ions. We discuss a field cage design, and the systematic error on the basis of beam size and emittance, considering the non-uniformity of the fields, the space-charge effect of the beam, and the lattice parameter errors.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL019  
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WEPAL021 Study of a Tuner for a High-Accuracy Bunch Shape Monitor linac, insertion, resonance, cavity 2200
 
  • K. Moriya, Y. Kawane, A. Miura
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • K. Futatsukawa, T. Miyao
    KEK, Ibaraki, Japan
 
  In the J-PARC Linac, development and higher precision of Bunch Shape Monitor (BSM) have been progressed for measuring the longitudinal beam distribution. To transform a longitudinal beam-profile into transverse one with an rf field, we need the field having an acceleration synchronizing frequency. An rf deflector of BSM consists of a half λ cylindrical cavity and two electrodes for deflection. In general, the resonance frequency can be tuned by adjusting the electrode length. We designed the new tuner with CST Studio. We can control the resonance frequency by Adjusting not only the electrode length but the cavity volume. We found the optimum lengths of electrode and volume for tuning. We introduce development of the new rf tuner for BSM in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL021  
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WEPAL024 High Precision Beam Parameter Stabilization for P2 at MESA experiment, cavity, controls, resonance 2209
 
  • R.F.K. Kempf, J. Diefenbach
    IKP, Mainz, Germany
  • K. Aulenbacher
    HIM, Mainz, Germany
 
  Funding: Cluster of Excellence PRISMA (EXC 1098/2014) German Research Foundation DFG (GRK 2128)
The experiment P2 will measure the weak mixing angle with an all-time high precision via electron-proton scattering. The measured physics asymmetry and its uncertainty has to be corrected by the apparatus' asymmetry, which is generated by helicity correlated fluctuations of the beam parameters position, angle, intensity and energy. This Poster will describe how the high precision of 0.1 ppb of the parity violating asymmetry can be provided by the high precision measurements of the parameters position, angle and intensity.
 
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WEPAL026 High Repetition Rate, Single-Shot Electro-Optical Monitoring of Longitudinal Electron Bunch Dynamics Using the Linear Array Detector KALYPSO storage-ring, laser, radiation, FEL 2216
 
  • G. Niehues, E. Blomley, M. Brosi, E. Bründermann, M. Caselle, S. Funkner, A.-S. Müller, M.J. Nasse, L. Rota, M. Schuh, P. Schönfeldt, M. Weber
    KIT, Eggenstein-Leopoldshafen, Germany
  • N. Hiller
    PSI, Villigen PSI, Switzerland
 
  Funding: This work is funded by the BMBF contract numbers: 05K13VKA and 05K16VKA.
High repetition rate diagnostics are required when detecting single-shot electro-optical (EO) bunch profiles. The KIT storage ring KARA (KArlsruhe Research Accelerator) is the first storage ring in the world that has a near-field EO bunch-profile monitor in operation. By imprinting longitudinal electron bunch profiles onto chirped laser pulses, single-shot detection is feasible. However, limitations of available detection systems are challenging: The constraints are either given by the repetition rate or the duration of the consecutive acquisitions. Two strategies can overcome these limitations: Based on the photonic time-stretch method, the ps laser pulses can be stretched to the ns range using km long fibers. The readout with a high-bandwidth oscilloscope then enables a single-shot detection at high repetition rates. The other strategy is the development of dedicated ultra-fast photodetector arrays allowing direct detection of the ps pulses at MHz repetition rates. We developed KALYPSO, a linear detector array with a DAQ allowing to record high data-rates over long time scales. Here, we present recent results of studies of the longitudinal electron bunch dynamics using KALYPSO.
 
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WEPAL035 The Synchronization System of the Thomx Accelerator linac, HOM, laser, distributed 2243
 
  • N. Delerue, V. Chaumat, R. Chiche, N. ElKamchi, H. Monard, F. Wicek
    LAL, Orsay, France
  • B. Lucas
    CNRS LPGP Univ Paris Sud, Orsay, France
 
  Funding: CNRS and ANR
The ThomX compact light source uses a 50 MeV ring to produce X-rays by Compton scattering. For historical reasons the linac and the ring could not operate at harmonic frequencies of each other. A heterodyne synchronization system has been designed for this accelerator. This synchronization is based on mixing the two RF frequencies to produce an heterodyne trigger signal and that is then distributed to the users. Bench tests of the system has demonstrated a jitter of less than 2 ps. We describe here this synchronization system.
 
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WEPAL040 High Precision Synchronization Development for HiRES, the Ultrafast Electron Diffraction Beamline at LBNL laser, controls, LLRF, gun 2262
 
  • Y. Yang, K.M. Baptiste, M. Betz, L.R. Doolittle, Q. Du, D. Filippetto, G. Huang, F. Ji
    LBNL, Berkeley, California, USA
 
  Precise synchronization between the laser and electron is critical for the pump-probe experiments in the HiRES Ultrafast Electron Diffraction facility. We are upgrading the LLRF and laser control system, which ultimately aims at a synchronization below 50 fs RMS between the pump laser pulse and electron probe at the sample plane. Such target poses tight requirements on the RF field stability both in amplitude and phase, and on the synchronization between the RF field and the laser repetition rate. We are presently developing a new LLRF system that has the potential to decrease the overall noise, reaching the required stability of tens of ppm on RF amplitude and phase. For the laser control side, we are replacing the long coaxial cables with fibers for both control signal transmission and laser signal reception. The control transmission side has been implemented, and the timing jitter has been reduced.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL040  
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WEPAL044 ENSOLVE : A Simulation Code for FXR LIA Downstream Section emittance, solenoid, target, space-charge 2271
 
  • Y.H. Wu, Y.-J. Chen
    LLNL, Livermore, California, USA
 
  Funding: This work was performed under the auspi-ces of the U.S. Department of Energy by Law-rence Livermore National Laboratory under Contract DE-AC52-07NA27344.
In this paper, we describe an envelope code, ENSOLVE. It solves the rms beam envelope equation by including space change depression of the potential, spherical aberration of the so-lenoidal lens, emittance growth and focusing effects of backstreaming ions in the final focus region. In this paper, we focus on the physics included for beam transport simulations in the downstream section of flash x-ray radiography linear induction accelerators, such as FXR LIA. We have used ENSOLVE to design final focus tunes for FXR LIA downstream section
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL044  
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WEPAL045 An Electrostatic Fixed-Slit Emittance Measurement System emittance, cathode, focusing, FEL 2274
 
  • J.W. Lewellen, H.L. Andrews, R.L. Fleming, K.E. Nichols, E.I. Simakov
    LANL, Los Alamos, New Mexico, USA
 
  Funding: Los Alamos National Laboratory LDRD Program
The emittance of a field emission cathode can be difficult to measure close to the emitter, due to the high average current density of the beam and the potential for desorbed material from an imaging screen to contaminate the cathode. We present the design for a dual fixed-slit emittance measurement system for a field emitter cathode, implemented using electrostatic deflecting plates. Results from fabrication and initial testing will be presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL045  
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WEPAL051 Mirascope Residual-Gas Luminescent Beam Profile Monitors controls, diagnostics, proton, operation 2291
 
  • V.G. Dudnikov, R.J. Abrams, M.A. Cummings
    Muons, Inc, Illinois, USA
 
  Muons, Inc. proposes to develop a Residual-Gas Beam Profile Monitor for Transfer Lines with pulse-to-pulse precision of better than 0.1 mm in position and size that will operate over a wide range of proton beam intensities including those needed for multi-MW beams of future facilities. Traditional solid-based beam intercepting instrumentation produces unallowable levels of radiation at high powers. Our alternative approach is to use a low mass residual-gas profile monitor, where ionization electrons are collected along extended magnetic field lines and the gas composi-tion and pressure in the beam pipe are locally controlled to minimize unwanted radiation and to improve resolu-tion. Beam Induced Fluorescence profile monitor with micrascope light collection is proposed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL051  
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WEPAL059 Observation and Suppression of Beam Orbit Drift Due to Path Length Changes and Thermal Effect in TPS site, feedback, controls, operation 2313
 
  • P.C. Chiu, K.T. Hsu, K.H. Hu, C.H. Huang, C.-C. Kuo
    NSRRC, Hsinchu, Taiwan
 
  Tidal effect, ambient temperature fluctuation and other effects of the TPS site can cause the path length changes of the electron beam in the TPS storage ring. Off-energy orbit drifts from the path length change, if not varying the RF frequency, cannot be properly corrected by the horizontal correctors and this causes the fast orbit feedback system over its normal working range. RF frequency adjustment loop is therefore applied to compensate for the circumference change based on the accumulating corrector strengths of the fast orbit feedback system. Implementation and operational experiences will be discussed in the report.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL059  
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WEPAL066 Determination of RF Resonator Axis Inclination to Beam Axis in Electron-Positron Storage Ring experiment, resonance, kicker, positron 2330
 
  • Leshenok D. Leshenok
    NSU, Novosibirsk, Russia
  • S.A. Nikitin
    BINP SB RAS, Novosibirsk, Russia
 
  We proposed and tested the method that allows obtaining of an upper limit for an angle of the RF resonator axis inclination relative to a beam axis. Such disturbance gives an additional contribution to separation of electron and positron orbits due to action of the transverse component of the electric field. In the horizontal plane, this effect can lead to increase of the difference between electrons and positrons spin precession frequencies in a storage mono-ring collider. This effect can play a great role in FCC. At the angular disturbance of axis in the certain VEPP-4M RF resonators ~10-3 rad, the difference between the spin frequencies is about 10-8. Our method is based on resonant excitation of betatron oscillations using phase modulation of the master oscillator of the RF system. The maximal amplitude of the enforced oscillations is measured by the counting rate of the VEPP-4M Touschek polarimeter scintillation counters. Comparison of the obtained results with the data of the special calibration experiment allows estimating the value of the inclination angle. In this calibrated experiment the betatron oscillations excite using the VEPP-4M kicker.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL066  
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WEPAL074 Commissioning of the Operational Laser Emittance Monitors for LINAC4 at CERN laser, detector, emittance, linac 2357
 
  • T. Hofmann, G.E. Boorman, A. Bosco, S.M. Gibson
    Royal Holloway, University of London, Surrey, United Kingdom
  • F. Roncarolo
    CERN, Geneva, Switzerland
 
  A laser-based emittance monitor has been developed to non-invasively measure the transverse emittance of the LINAC4 H beam at its top energy of 160MeV. After testing several sub-systems of the instrument during linac commissioning at intermediate energies, two instruments are now permanently installed. These instruments use a pulsed laser beam delivered to the accelerator tunnel by optical fibres before final focusing onto the H beam. The photons in the laser pulse detach electrons from the H ions, which can then be deflected into an electron multiplier. In addition, the resulting neutral H0 atoms can be separated from the main beam by a dipole magnet before being recorded by downstream diamond strip-detectors. By scanning the laser in the horizontal and vertical plane the beam profiles are obtained from the electron signals and the emittance can be reconstructed by the H0 profiles at the diamond detectors. This paper describes the final system layout that consists of two independent instruments, each measuring profile and emittance of the H beam in the horizontal and vertical plane and discusses the preliminary commissioning results.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL074  
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WEPAL075 Time-Resolved Transverse Beam Profile Measurements with a Rest Gas Ionisation Profile Monitor Based on Hybrid Pixel Detectors detector, background, proton, site 2361
 
  • S. Levasseur, S.M. Gibson
    Royal Holloway, University of London, Surrey, United Kingdom
  • W. Bertsche, H. Sandberg
    UMAN, Manchester, United Kingdom
  • D. Bodart, A. Huschauer, G. Schneider, J.W. Storey, R. Veness
    CERN, Geneva, Switzerland
  • M. Sapinski
    GSI, Darmstadt, Germany
  • K. Satou
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
 
  A novel rest gas ionisation profile monitor which aims to provide continuous, bunch-by-bunch and turn-by-turn measurement of the transverse beam profile has recently been in- stalled in the CERN Proton Synchrotron (PS) as part of the LHC Injector Upgrade (LIU) project. The instrument consists of an electric drift field to transport ionisation electrons produced by beam-gas interaction onto a measurement plane, and a magnetic field to maintain the transverse position of the ionisation electrons. The electron detector located at the measurement plane is based on four in-vacuum hybrid pixel detectors. The detectors record the position, time and energy of single ionisation electrons with unprecedented precision compared to traditional MCP based techniques. Continuous transverse beam profile measurements for LHC-type beams in the PS will be presented, demonstrating the unique capabilities of the instrument to provide new insights into beam dynamics throughout the acceleration cycle.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL075  
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WEPMF002 Operational Experience with IOTs at Alba Synchrotron cavity, cathode, operation, controls 2372
 
  • J.R. Ocampo, B. Bravo, R. Fos, F. Pérez, A. Salom, P. Solans
    ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
  • S. Bethuys, A. Beunas, M. Grezaud, P. Reynaud
    TED, Velizy-Villacoublay, France
  • M. Boyle, J. Cipolla, W.F. Coyle, H. Schult
    L-3, Williamsport, Pennsylvania, USA
 
  ALBA is a 3 GeV Synchrotron light source in operation since 2012. The RF systems are based in Inductive Output Tube (IOT) transmitters. A total of 13 80 kW IOT amplifiers are used to power the Storage Ring and Booster cavities at 500 MHz. The transmitters were initially configured to operate the TH-793-1 and TH-794 IOT from THALES Electron devices. On 2015, the amplifiers have been adapted to operate also the TH-795 from THALES and the L4444-C from L3 Communications. In this paper, a brief overview of the differences between these IOT models will be presented, as well as operation results for each type of IOT from the point of view of performance, reliability and durability.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF002  
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WEPMF010 Laser Treatment of Niobium Surface for SRF Aplications laser, cavity, niobium, experiment 2387
 
  • V. Porshyn, D. Lützenkirchen-Hecht, P. Serbun
    Bergische Universität Wuppertal, Wuppertal, Germany
  • H. Bürger, S. Soykarci
    University of Wuppertal, Wuppertal, Germany
 
  Funding: The research was funded by the German Federal Ministry of Education and Research (BMBF) under project number 05H15PXRB1.
We report on a laser surface treatment of high purity niobium (110) single crystals. Typical surface defects like scratches, pits, sharp rims and holes were eliminated by a focused pulsed ns-laser beam. A laser fluence of about 0.68 J/cm2 and 40 - 80 pulses per spot were required to induce well detectable surface modifications. The remelted surface was sufficiently smooth, but exhibited also a number of wave structures. Thus, the surface roughness slightly increased with increasing number of pulses. Finally, boiling traces and μm-deep ablation were observed and studied as well. Local field electron emission measurements showed no emission up to 700 MV/m from a moderate remelted area below the boiling point.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF010  
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WEPMF012 Power Requirement and Preliminary Coupler Design for the eRHIC Crab Cavity System cavity, operation, proton, SRF 2394
 
  • S. Verdú-Andrés, I. Ben-Zvi, D. Holmes, Q. Wu
    BNL, Upton, Long Island, New York, USA
  • I. Ben-Zvi
    Stony Brook University, Stony Brook, USA
 
  Funding: Work supported by Brookhaven Science Associates LLC under contract no. DE-SC0012704 with the U.S. Department of Energy.
Crab cavities are deflecting cavities operated in such a way that the bunch center is in synchronism with the zero-crossing kick voltage. In that case, beam loading is zero for an on-axis beam. The crab cavity system of the future electron-ion collider eRHIC will manipulate 275 GeV proton beams. At high energies, the beam offset can be as large as 2 mm (including mechanical and electrical offset tolerances). The beam loading resulting from such offset can greatly incur in large power requirements to the RF amplifier. The choice of external Q for the Fundamental Power Coupler (FPC) is critical to limit the power requirement to practical values. The loaded Q of the eRHIC crab cavities is mainly governed by the external Q of the FPC, so the external Q will also define the cavity bandwidth and thus the tuning requirements to counteract frequency transients from external perturbations. This paper discusses the choice of external Q for the FPC of the eRHIC crab cavities and introduces the design of a preliminary FPC antenna concept that would provide the appropriate external Q.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF012  
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WEPMF020 Pulsed Systems for eRHIC Beam Injection and Extraction injection, kicker, extraction, storage-ring 2410
 
  • W. Zhang, M. Blaskiewicz, A. Hershcovitch, C.J. Liaw, H. Lovelace III, M. Mapes, G.T. McIntyre, J.-L. Mi, C. Montag, C. Pai, V. Ptitsyn, J. Sandberg, N. Tsoupas, J.E. Tuozzolo, G.M. Wang, W.-T. Weng, F.J. Willeke, H. Witte, Q. Wu
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The electron-ion collider eRHIC requires a variety of kickers and septa for injection and extraction of beams throughout the entire collider complex. We plan to use pulsed systems for beam injection and extraction in Electron RCS, Electron Storage Ring, and Hadron ring. In this paper, we describe the pulsed systems required for beam transfer in the eRHIC Ring-Ring Pre-conceptual Design. We will outline the parameter ranges, technology choices, and opportunities for research and development in pulsed power technology.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF020  
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WEPMF022 Coulped Multiphysics Simulation for the Water Cooling Layout of a Rhodotron Cavity cavity, simulation, operation, vacuum 2416
 
  • L. Yang, X. He, H. Li, S.Q. Liao
    CAEP/IFP, Mainyang, Sichuan, People's Republic of China
 
  A Rhodotron-based electron accelerator served as micro-focused X-ray source is under development at IFP, CAEP. The RF-cavity, running in long pulse/ CW mode, will deliver 9 MeV energy to electron beams after multiple accelerations within the same field at a frequency of 107.5MHz. A substantial amount of average power loss with tens of kW will be dissipated on the RF surface of the cavity to maintain the operational field level. Efficient water cooling is critical to prevent large scale temperature rise for stable operation sake. Reasonable prediction of temperature rise becomes essential to assess a certain cooling layout in the design phase. The frequency drift and thermal stress on account of temperature variation and gradient on cavity wall respectively, could be computed accordingly. This paper presents a comprehensive coupled simulation involving electromagnetic, thermal and structural for the RF-cavity of Rhodotron.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF022  
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WEPMF030 Optimization of Klystron Efficiency with MOGA klystron, cavity, simulation, bunching 2419
 
  • C. Meng, X. He, S. Pei, S.C. Wang, O. Xiao, Z.S. Zhou
    IHEP, Beijing, People's Republic of China
 
  As the very important element of accelerator the klystron provide power to cavities for accelerating. Considering the accelerator cost of construction and running, the improvement of klystron efficiency is one developing hotspot of klystron research. In this paper the optimization method of klystron efficiency with MOGA based on 1D simulation program is proposed and the influences on klystron efficiency will be discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF030  
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WEPMF032 Experimental Studies on Secondary Electron Emission Characteristics for Chamber Materials of Accelerators experiment, detector, vacuum, neutron 2425
 
  • Y. Jiao, Z. Duan, W.B. Liu, Y.D. Liu
    IHEP, Beijing, People's Republic of China
  • Liu. S. Liu
    Institute of High Energy Physics (IHEP), People's Republic of China
  • P.C. Wang
    DNSC, Dongguan, People's Republic of China
 
  Funding: National Natural Science Foundation of China (11275221) and Key Laboratory Foundation of Particle Acceleration Physics &Technology (Y5294106TD)
Secondary electron emission (SEE) of surface is origin of multipacting effect which could seriously deteriorate beam quality and even perturb the normal operation of particle accelerators. Experimental measurements on secondary electron yield (SEY) on different materials and coating have been developed in many accelerator laboratory. In fact, the SEY is just one parameter of secondary electron emission characteristics which include spatial and energy distribution of emitted electrons. A novel experimental apparatus was set up in China Spallation Neutron Source (CSNS) and innovative measurement methods were applied to obtain the whole characteristics of SEE. With some traditional accelerator chamber materials such as Cu, Al, TiN, SEY dependence on primary electron energy and beam injection angle, spatial and energy distribution of emitted secondary electrons were achieved with this measurement apparatus. This contribution also tries to give all the experimental results a reasonable theoretical analysis.
 
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WEPMF034 Development of Superconducting RF Double Spoke Cavity at IHEP cavity, coupling, target, proton 2432
 
  • Z.Q. Zhou, H.F.S. Feisi, W.M. Pan
    IHEP, Beijing, People's Republic of China
 
  Funding: State Key Development Program for Basic Research of China (Grant No.2014CB845500)
The China Initiative Accelerator Driven System (CiADS) has been approved to transmute long-lived radi-oisotopes in used nuclear fuel into shorter-lived fission products. IHEP is developing a 325MHz double spoke cavity at β0 of 0.5 for the CiADS linac. The cavity shape was optimized to minimize Ep/Ea while keeping Bp/Ep reasonably low, while the multipacting was analyzed. Meanwhile, mechanical design was applied to check stress, Lorentz force detuning and microphonic effects, and to minimize pressure sensitivity. A new RF coupling scheme was proposed to avoid electrons hitting directly on ceramic window. The detailed design for the cavity is addressed in this paper.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF034  
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WEPMF039 Experimental Results on the Field and Frequency Dependence of the Surface Resistance of Niobium Cavities cavity, niobium, vacuum, experiment 2451
 
  • P.N. Koufalis, M. Liepe, J.T. Maniscalco, T.E. Oseroff
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  We investigate the field and frequency dependence of the surface resistance of single-cell niobium cavities as a function of surface treatment at 1.3, 2.6, and 3.9 GHz. The surface resistance is broken down into two parts: the temperature-independent residual resistance and the temperature-dependent BCS resistance. While the low-field BCS resistance is known to vary quadratically with frequency, the exact dependence of the BCS and residual resistances on field at higher frequencies are important topics for further investigation. We offer results on a systematic experimental study of the residual and BCS resistance as a function of frequency and field for clean niobium and high-temperature nitrogen-doped niobium.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF039  
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WEPMF051 Multipacting in an RF Window: Simulations and Measurements multipactoring, simulation, resonance, gun 2483
 
  • M. Bousonville, S. Choroba
    DESY, Hamburg, Germany
 
  Electron guns are used in the accelerators of the European XFEL and FLASH. They are operated at 1.3 GHz. The RF peak power is 5 MW at 650 us pulse width and 10 Hz repetition rate. In order to understand the multipacting that occurs during conditioning, it was simulated in the RF window type that is used for the electron gun in the XFEL. The reduction in secondary emission yield associated with conditioning was taken into account. Since the RF windows are tested with high power on a test stand before their use, without the electron gun, measurement results are available which are compared with the simulation results. The main advantage of the simulation compared to the measurement is that the locations of multipacting can be determined in the RF window. This could be helpful for the development of high-power RF components in the future, in order to detect pronounced multipacting resonances even before production and to avoid them by design changes.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF051  
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WEPMF055 The REGAE Accelerator Vacuum System gun, vacuum, cathode, operation 2493
 
  • S. Lederer, K. Flöttmann, L. Lilje, N. Plambeck
    DESY, Hamburg, Germany
 
  Since 2011 the Relativistic Electron Gun for Atomic Exploration (REGAE) is operated at DESY in Hamburg. The accelerator consists mainly of a high gradient S-band RF-gun, which generates ultra-low emittance electron bunches, and an S-band RF-buncher cavity for bunch compression. In this contribution we describe the vacuum system of the REGAE accelerator. We will cover design aspects, applied cleaning and installation procedures as well as operation experience over the last years.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF055  
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WEPMF061 High Gradient Pulsed Quadrupoles for Novel Accelerators and Space Charge Limited Beam Transport plasma, quadrupole, focusing, wakefield 2505
 
  • C. Tenholt
    CERN, Geneva, Switzerland
  • G. Loisch, F. Stephan
    DESY Zeuthen, Zeuthen, Germany
  • B. Marchetti
    DESY, Hamburg, Germany
 
  Novel acceleration schemes like plasma wake-field based accelerators demand for high gradient focusing elements to match the Twiss parameters in the plasma to the transport lattice of the conventional accelerator beamlines, with typically much higher beta-functions. There are multiple candidates for achieving high gradient focusing fields, each one having certain drawbacks. Permanent magnets are limited in tunability, plasma lenses might degrade the transverse beam quality significantly and conventional magnets cannot reach very high gradients and often cannot be placed in direct proximity of the plasma accelerator because of their size. In this paper we present design considerations and simulations on compact, high gradient, pulsed quadrupoles, that could be used e.g. for final focusing of space charge dominated bunches into a LWFA (Laser Wake-Field Accelerator) at SINBAD or other facilities with similar demands. The target design gradient is 200 T/m at a physical aperture on the order of 10 mm.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF061  
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WEPMF066 Fabrication of Split-Section X-band Structure Using Elastic Averaging vacuum, alignment, coupling, gun 2521
 
  • P. Borchard, S.A. Appert, J.S. Hoh
    Dymenso LLC, San Francisco, USA
 
  Conventional accelerator structures are manufactured using axial stacks of cylindrical components which, when brazed together, form the accelerator cell structure. Splitting the accelerator structure into two sections along the beam axis allows for a significant reduction in part count and vacuum joint length. The resultant single and coplanar vacuum joint between the two split sections allows for joining techniques such as electron beam welding or brazing of the parts to form the accelerator vacuum envelope. High precision alignment of the two sections is achieved through an elastic averaging interface coupling where improved accuracy is derived from the averaging of errors over a large number of relatively compliant contacting members. The monoblock split sections allow for highly optimized cooling configurations with enhanced heat removal in high heat flux regions, reducing vacuum wall thermal stresses and enabling higher power operation. This paper describes the engineering and manufacturing of four generations of brazed and electron beam welded X-band accelerator structures at both 9.3 GHz and 11.4 GHz frequencies.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF066  
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WEPMF067 A High Gradient Solution for Increasing the Energy of the FERMI Linac linac, FEL, wakefield, laser 2525
 
  • C. Serpico, I. Cudin, S. Di Mitri, N. Shafqat, M. Svandrlik
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • M. Bopp, R. Zennaro
    PSI, Villigen PSI, Switzerland
 
  FERMI is the seeded Free Electron Laser (FEL) user facility at Elettra laboratory in Trieste, operating in the VUV to soft X-rays spectral range. In order to extend the FEL spectral range to shorter wavelengths, a feasibility study for increasing the Linac energy from 1.5 GeV to 1.8 GeV is actually going on. The design of new S-band accelerating structures, intended to replace the present Backward Travelling Wave sections, is presented. Such design is tailored for high gradient operation, low breakdown rates and low wakefield contribution. In this paper, we will also present the first, short prototype that has been built in collaboration with Paul Scherrer Institute (PSI).  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF067  
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WEPMF068 Inexpensive Brazeless Accelerator Prototype gun, cavity, vacuum, operation 2528
 
  • S.P. Antipov, R.A. Kostin, S.V. Kuzikov
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • A.A. Vikharev
    IAP/RAS, Nizhny Novgorod, Russia
 
  Funding: DOE SBIR
A simple, inexpensive way to manufacture a standard radio frequency (RF) driven particle accelerator is presented. The simplification comes from two innovations: utilization of LCLS gun type RF design to avoid an expensive brazing process and copper plating of stainless steel that further reduces manufacturing cost. This is realized by a special structure design where accelerating structure cells are made out of copper plated stainless steel with knife edges and structure irises - copper disks acts also as gaskets for vacuum and RF seal. Besides the reduced cost, brazeless assembly allows integration of effective cooling and magnet optics elements into accelerator cells. Here we report on manufacturing and testing of brazeless accelerator prototype.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF068  
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WEPMF073 Adaptation of the Cryogenic System Capacity for the LHC Dynamic Heat Load - Operational Experience cryogenics, controls, operation, HOM 2541
 
  • K. Brodzinski, B. Bradu, S.D. Claudet, D. Delikaris, L.P. Delprat, G. Ferlin
    CERN, Geneva, Switzerland
 
  During second LHC physics operation period (Run2), between 2015 and 2018, the accelerator operation modes and beam parameters have been adapted thus allowing significantly improved integrated luminosity production. Increased energy, intensity and adapted beam operation schemes with 25 ns of inter-bunches spacing have an essential influence on the dynamic heat load generation with direct impact on the cryogenic cooling system. In order to cope with significantly higher than expected beam induced thermal load, the cryogenic system was tuned and optimized to adapt the required refrigeration capacity to the beam operational requirements. The most challenging part of tuning was focused on the dynamic heat load compensation on the beam screens circuits. The paper will provide the overview on the main differences between the theoretical heat load values considered for initial design and the on-line measurements performed on cryogenic LHC sectors. Finally, the paper will summarize the methodology and tools implemented in the cryogenic process control system allowing the highly efficient on-line adaptation of the refrigeration power with respect to the beam induced heat load distribution.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF073  
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WEPMG005 First Beam Test of Laser Engineered Surface Structures (LESS) at Cryogenic Temperature in CERN SPS Accelerator laser, vacuum, cryogenics, multipactoring 2616
 
  • R. Salemme, V. Baglin, S. Calatroni, P. Chiggiato, B. Di Girolamo, E. Garcia-Tabares Valdivieso, B. Jenninger, L. Prever-Loiri, M. Sitko
    CERN, Geneva, Switzerland
  • A. Abdolvand, S. Wackerow
    University of Dundee, Nethergate, Dundee, Scotland, United Kingdom
  • R. Salemme
    ITER Organization, St. Paul lez Durance, France
 
  Electron cloud mitigation is an essential requirement for accelerators of positive particles with high intensity beams to guarantee beam stability and limited heat load in cryogenic systems. Laser Engineered Surface Structures (LESS) are being considered, within the High Luminosity upgrade of the LHC collider at CERN (HL-LHC), as an option to reduce the Secondary Electron Yield (SEY) of the surfaces facing the beam, thus suppressing the elec-tron cloud phenomenon. As part of this study, a 2.2 m long Beam Screen (BS) with LESS has been tested at cryogenic temperature in the COLD bore EXperiment (COLDEX) facility in the SPS accelerator at CERN. In this paper, we describe the manufacturing procedure of the beam screen, the employed laser treatment technique and discuss our first observations in COLDEX confirming electron cloud suppression.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMG005  
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WEPMK003 An Upgraded LHC Injection Kicker Magnet kicker, injection, vacuum, impedance 2632
 
  • M.J. Barnes, C. Bracco, G. Bregliozzi, A. Chmielinska, L. Ducimetière, B. Goddard, T. Kramer, H. Neupert, L. Vega Cid, V. Vlachodimitropoulos, W.J.M. Weterings, C. Yin Vallgren
    CERN, Geneva, Switzerland
  • A. Chmielinska
    EPFL, Lausanne, Switzerland
 
  Funding: Work supported by the HL-LHC project.
An upgrade of the LHC injection kickers is necessary for HL-LHC to avoid excessive beam induced heating of these magnets: the intensity of the HL-LHC beam will be twice that of LHC. In addition, in the event that it is necessary to exchange an injection kicker magnet, the newly installed kicker magnet would limit HL-LHC operation for a few hundred hours due to dynamic vacuum activity. Extensive studies have been carried out to identify practical solutions to these problems: these include redistributing a significant portion of the beam induced power deposition to ferrite parts of the kicker magnet which are not at pulsed high voltage and water cooling of these parts. Furthermore a surface coating, to mitigate dynamic vacuum activity, has been selected. The results of these studies, except for water cooling, have been implemented on an upgraded LHC injection kicker magnet: this magnet was installed in the LHC during the 2017-18 Year End Technical Stop. This paper presents the upgrades, including some test and measurement results.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMK003  
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WEPML038 Plasma Window as a Pressure Valve for FAIR plasma, cathode, experiment, vacuum 2776
 
  • B. F. Bohlender, M. Iberler, J. Jacoby
    IAP, Frankfurt am Main, Germany
  • A. Michel
    Goethe Universität Frankfurt, Frankfurt am Main, Germany
 
  Funding: Funded by BMBF, Ref. No: 05P15 RFRBA and HIC for FAIR
This contribution shows the progress in the development of a plasma window at the institute for applied physics at Goethe University Frankfurt. A plasma window* is a membrane free transition between two regions of different pressure, enabling beam transmission from a rough vacuum area (~1 mbar) to a higher pressure (up to 1 bar) region on short length scales. In comparison to differential pumping stages a length reduction by a factor of up to 100 is achievable, while the absence of a solid membrane yields prolonged operation time. The sealing effect is based on the high temperature arc discharge sustained in a cooled copper channel between the pressure regimes. Due to a bulk temperature around 10,000K** the viscosity of the gas is dramatically increased, leading to a slower gas flow, enabling a higher pressure gradient. This contribution will present first results regarding the pressure gradient in dependence of the discharge current and the aperture. Until now, a pressure factor around 100 has been established for well over 50 min. This contribution goes along with the one from Mr. A. Michel, he focuses on the spectroscopic analysis of the arc plasma.
*A. Hershcovitch, J. Appl. Phys., AIP Publishing (1995) 78, 5283
**Y.E. Krasik et al., "Plasma Window Characterization", J. Appl. Phys., AIP Publishing (2007) 101, 053305.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML038  
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WEPML046 Multipactor Discharge in Superconducting Accelerating CH Cavities multipactoring, cavity, linac, heavy-ion 2800
 
  • M. Gusarova, D. I. Kiselev
    MEPhI, Moscow, Russia
  • F.D. Dziuba, T. Kürzeder, M. Miski-Oglu
    HIM, Mainz, Germany
  • M. Gusarova
    JINR, Dubna, Moscow Region, Russia
 
  The results of numerical simulations of multipacting discharge in a superconducting accelerating CH cavity are presented in this paper. The localization of multipactor trajectories in the 15-gap 217 MHz superconducting (sc) CH cavity at various levels of accelerating voltage is considered.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML046  
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WEPML053 Availability of the TiN Coating-Free Ceramic in the STF-type Power Coupler for ILC SRF, vacuum, cryomodule, GUI 2819
 
  • Y. Yamamoto, E. Kako, T. Matsumoto, S. Michizono, A. Yamamoto
    KEK, Ibaraki, Japan
  • M. Irikura, M. Ishibashi, H. Yasutake
    Toshiba Electron Tubes & Devices Co., Ltd (TETD), Tochigi, Japan
  • C. Julie, E. Montesinos
    CERN, Geneva, Switzerland
 
  In the Superconducting RF Test Facility (STF) in KEK, the research and development for the power coupler with the TiN coating-free ceramic has been done from 2014. In 2016, the high power test at the test bench was stopped due to the worse vacuum level by the unusual heating around the RF window with the TiN coating-free ceramic and the coaxial tapered section, which was caused by the enormous emission of the secondary electrons from the ceramic. And, the situation was never also changed by the ultrapure water rinsing for the power couplers several times. However, in 2017, the ultrasonic rinsing was done for the power couplers for the first time by the collaboration between KEK and TETD. After that, the situation was drastically improved, and the secondary electron emission almost disappeared even in the higher RF duty. This shows that the TiN coating-free ceramic is the prospective item for the cost reduction in ILC. In this report, the recent result for the power coupler with the TiN coating-free ceramic will be presented in detailed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML053  
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WEPML058 Observation of Pressure Bursts in the SuperKEKB Positron Ring MMI, positron, luminosity, operation 2830
 
  • S. Terui, H. Hisamatsu, T. Ishibashi, K. Kanazawa, K. Shibata, M. Shirai, Y. Suetsugu
    KEK, Ibaraki, Japan
 
  The SuperKEKB is an electron-positron collider with asymmetric energies in KEK aiming an extremely high luminosity of 8x1035 cm-2 s-1 using a nano-beam scheme. In the Phase 1 commissioning from February to June, 2016, the vacuum system of the main ring worked well as a whole at stored beam currents of approximately 1 A. However, the localized pressure bursts accompanied by beam losses were observed in the positron ring. The beam loss monitors triggered beam aborts, and the phenomena has became an obstacle to the beam commissioning. These pressure bursts were frequently observed from the early stage of the commissioning. Most of the pressure bursts occurred near or inside of aluminum-alloy beam pipes in dipole magnets, which have grooved surface at the top and bottom sides. The various observations indicates that the most probable cause of this phenomenon was the collision between the dusts dropped from the grooves and the circulating positron beam. We report the properties and the probable causes of the pressure bursts, and the possible mitigation methods. Some results of the countermeasures taken prior to the ongoing Phase-2 commissioning will be also presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML058  
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WEPML059 Status of the SuperKEKB Vacuum System in the Phase-2 Commissioning MMI, vacuum, wiggler, permanent-magnet 2833
 
  • Y. Suetsugu, H. Hisamatsu, T. Ishibashi, K. Kanazawa, K. Shibata, M. Shirai, S. Terui
    KEK, Ibaraki, Japan
 
  The SuperKEKB is an electron-positron collider with asymmetric energies in KEK aiming an extremely high luminosity of 8.0·1035 /cm2/s. In the Phase-1 commissioning from February to June, 2016, the vacuum system of the main ring worked well as a whole at stored beam currents of approximately 1 A. However, several problems were found for the future commissioning, and various countermeasures were taken against these problems during the shutdown period before starting the Phase-2 commissioning. For example, permanent magnets were placed around the beam pipe to suppress the electron cloud effect in the positron ring. Other than these works, new beam pipes for the collision point, the super-conducting final focusing magnets and the positron beam injection region were installed in the main ring. Additional six beam collimators were installed for reducing background noise of the particle detector. Furthermore, the vacuum system for new damping ring for the positron beam was constructed. Reported here will be the present status of the vacuum system of the main ring, and major results of the countermeasures taken prior to the Phase-2 commissioning.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML059  
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WEPML060 Yb/Nd Doped Hybrid Solid Laser of RF Gun and Beam Commissioning for Phase-II of SuperKEKB laser, gun, injection, MMI 2836
 
  • R. Zhang, T. Natsui, Y. Ogawa, M. Yoshida, X. Zhou
    KEK, Ibaraki, Japan
 
  For SuperKEKB project schedule of the phase-II, low emittance 1 nC electron beams were required with good stability and reliability at end of the linac. In the injector linac, several instruments have been installed. An Nd/Yb hybrid laser system is development with two beam lines light source. The both side of quasi-traveling wave side coupled cavity S-band RF gun were injected by the two sub μJ UV picosecond laser pulses at same times. And beam commissioning with the RF gun is in progress.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML060  
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WEPML076 The Magnetic Measurement of Enhancer-Dipole Magnet for CEPC collider, positron, collimation, dipole 2866
 
  • Z. Zhang, H. Wang
    IHEP, Beijing, People's Republic of China
 
  The CEPC (Circular Electron Positron Collider) project is in the pre-research stage. When the beam energy of booster is 120 GeV, the magnetic field of deflection magnet is 640 Gs. In order to save funds for scientific research, we also consider the injection energy of 6 GeV, the magnetic field of deflection magnet is 32 Gs. At the different current, the magnetic field value of the enhancer-dipole magnet can reach the beam energy range of 6 Gev-120 GeV. In such a requirements of magnetic field, the stability of the magnetic field value, repeatability, magnet magnetism, has become an important data for the design parameters of enhancer-dipole magnet. The magnet is measured with the Hall-Probe measurement facility by IHEP. In this paper, first written the procedure of motor control and collection by Labview software, then hen the excitation curve(repeat the measurement six times), transverse field distribution(repeat the measurement three times), and integral field distribution are measured. Based on the results of the analysis of large amounts of data, the stability and repeatability of the enhance-dipole magnet in different magnetic fields has summarized and analyzed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML076  
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THXGBD2 Overview of Undulator Concepts for Attosecond Single-Cycle Light undulator, FEL, laser, bunching 2878
 
  • A. Mak, V.A. Goryashko, P.M. Salen, G. K. Shamuilov
    Uppsala University, Uppsala, Sweden
  • D.J. Dunning, N. Thompson
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • D.J. Dunning, B.W.J. MᶜNeil, N. Thompson
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • J. Hebling, Z. Tibai, Gy. Tóth
    University of Pecs, Pécs, Hungary
  • Y. Kida, T. Tanaka
    RIKEN SPring-8 Center, Hyogo, Japan
  • B.W.J. MᶜNeil
    USTRAT/SUPA, Glasgow, United Kingdom
 
  Funding: Swedish Research Council (VR, 2016-04593); Stockholm-Uppsala Centre for Free-Electron Laser Research; C. F. Liljewalchs stipendiestiftelse.
The production of intense attosecond light pulses is an active area in accelerator research, motivated by the stringent demands of attosecond science: (i) short pulse duration for resolving the fast dynamics of electrons in atoms and molecules; (ii) high photon flux for probing and controlling such dynamics with high precision. While the free-electron laser (FEL) can deliver the highest brilliance amongst laboratory x-ray sources today, the pulse duration is typically 10-100 femtoseconds. A major obstacle to attaining attosecond duration is that the number of optical cycles increases with every undulator period. Hence, an FEL pulse typically contains tens or hundreds of cycles. In recent years, several novel concepts have been proposed to shift this paradigm, providing the basis for single-cycle pulses and paving the way towards high-brilliance attosecond light sources. This article gives an overview of these concepts.
 
slides icon Slides THXGBD2 [1.758 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THXGBD2  
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THXGBE2 Optical Diagnostics for Extreme Beam Conditions radiation, emittance, diagnostics, experiment 2896
 
  • R.B. Fiorito
    The University of Liverpool, Liverpool, United Kingdom
 
  The development of simple, fast, precise and robust beam diagnostics is absolutely necessary to optimize the performance of present accelerators and to satisfy the needs of future accelerators, in particular those with ex-treme properties such as high brightness FELs and plasma wake-field accelerators. This invited talk will present the underlying physics and results from simulation and experiments for a number of advanced optical beam diagnostics currently under development at various accelerator re-search laboratories including efforts at the Cockcroft Institute.  
slides icon Slides THXGBE2 [13.917 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THXGBE2  
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THYGBD4 Landau Damping by Electron Lenses proton, octupole, collider, betatron 2921
 
  • A.V. Burov, Y.I. Alexahin, V.D. Shiltsev, A. Valishev
    Fermilab, Batavia, Illinois, USA
 
  Modern and future particle accelerators employ increasingly higher intensity and brighter beams of charged particles and become operationally limited by coherent beam instabilities. Usual methods to control the instabilities, such as octupole magnets, beam feedback dampers and use of chromatic effects, become less effective and insufficient. We show that, in contrast, Lorentz forces of a low-energy, magnetically stabilized electron beam, or "electron lens", easily introduces transverse nonlinear focusing sufficient for Landau damping of transverse beam instabilities in accelerators. It is also important to note that, unlike other nonlinear elements, the electron lens provides the frequency spread mainly at the beam core, thus allowing much higher frequency spread without lifetime degradation. For the parameters of the Future Circular Collider, a single conventional electron lens a few meters long would provide stabilization superior to tens of thousands of superconducting octupole magnets.  
slides icon Slides THYGBD4 [4.502 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THYGBD4  
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THYGBE1 Applying Artificial Intelligence to Accelerators FEL, controls, feedback, network 2925
 
  • A. Scheinker, R.W. Garnett, D. Rees
    LANL, Los Alamos, New Mexico, USA
  • D.K. Bohler
    SLAC, Menlo Park, California, USA
  • A.L. Edelen, S.V. Milton
    CSU, Fort Collins, Colorado, USA
 
  Particle accelerators are being designed and operated over a wide range of complex beam phase space distributions. For example, the Linac Coherent Light Source (LCLS) upgrade, LCLS-II, is considering complex schemes such as two-color operation [1], while the plasma wake field acceleration facility for advanced accelerator experimental tests (FACET) upgrade, FACET-II, is planning on providing custom tailored current profiles [2]. Because of uncertainty due to limited diagnostics and time varying performance, such as thermal drifts, as well as collective effects and the complex coupling of large numbers of components, it is impossible to use simple look up tables for parameter settings in order to quickly switch between widely varying operating ranges. Several forms of artificial intelligence are currently being investigated in order to enable accelerators to quickly and automatically re-adjust component settings without human intervention. In this work we discuss recent progress in applying neural networks and adaptive feedback algorithms to enable automatic accelerator tuning and optimization.
[1] A. A. Lutman et al., Nat. Photonics 10.11, 745 (2016).
[2] V. Yakimenko et al., IPAC2016, Busan, Korea, 2016.
 
slides icon Slides THYGBE1 [14.256 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THYGBE1  
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THYGBE4 Early Phase 2 Results of LumiBelle2 for the SuperKEKB Electron Ring luminosity, background, simulation, photon 2934
 
  • S. Di Carlo, P. Bambade, D. Jehanno, V. Kubytskyi, C.G. Pang, Y. Peinaud, C. Rimbault
    LAL, Orsay, France
 
  We report on the early SuperKEKB Phase 2 operations of the fast luminosity monitor (LumiBelle2 project). Fast luminosity monitoring is required by the dithering feedback system, which is used to stabilize the beam in the presence of horizontal vibrations. In this report, we focus on the operations related to the electron side of LumiBelle2. Diamond sensors are located 30 meters downstream of the IP, just above, beside, and below the electron beam pipe. During early Phase 2, the sensors are used to measure the background, arising from beam-gas scattering. We present the hardware design, the detection algorithm, and the analysis of the background measurements taken up-to-date. The results are then compared with a detailed simulation of the background, in order to well understand the physical processes involved. The simulation is performed using SAD for generation and tracking purposes, while Geant4 is used to calculate the energy deposition in the diamond sensors.  
slides icon Slides THYGBE4 [3.091 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THYGBE4  
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THPAF005 Simulations of Modulator for Coherent Electron Cooling simulation, bunching, plasma, quadrupole 2953
 
  • J. Ma, V. Litvinenko, G. Wang
    BNL, Upton, Long Island, New York, USA
  • V. Litvinenko
    Stony Brook University, Stony Brook, USA
 
  Highly resolved numerical simulations have been performed using the code SPACE for the modulator, the first section of the Coherent electron cooling (CeC) device installed in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). Simulation results have been benchmarked with analytical solution using uniform electron beam with realistic thermal velocities. Electron bunches with Gaussian distribution and quadrupole field with realistic settings have been applied in the simulations to predict the modulation process and final bunching factors induced by ions with reference and off-reference energies in the CeC experiment at BNL RHIC.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF005  
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THPAF006 Simulations of Cooling Rate and Diffusion for Coherent Electron Cooling Experiment FEL, simulation, kicker, bunching 2957
 
  • J. Ma, V. Litvinenko, G. Wang
    BNL, Upton, Long Island, New York, USA
  • V. Litvinenko
    Stony Brook University, Stony Brook, USA
 
  Start-to-end numerical simulations have been performed using the code SPACE and GENESIS for the single pass of gold ions through the coherent electron cooling (CeC) device installed in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). Cooling rate of CeC experiment has been predicted using off-reference energy ions in a finite Gaussian electron beam through a realistic beam-line, in which settings of quadrupoles and free-electron laser (FEL) device are relevant to BNL RHIC.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF006  
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THPAF015 Beam Tracking Studies of Electron Cooling in ELENA proton, antiproton, simulation, emittance 2975
 
  • B. Veglia, J.R. Hunt, J. Resta-López, V. Rodin, C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • J.R. Hunt, J. Resta-López, V. Rodin, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
 
  Funding: This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 721559.
The Extra Low ENergy Antiproton storage ring (ELENA), which is currently being commissioned at CERN, will further decelerate antiprotons extracted from the Antiproton Decelerator (AD) from 5.3 MeV to energies as low as 100 keV. It will provide high quality beams for the antimatter experiments located within the AD hall. At such low energies, it is important to correctly evaluate the long term beam stability. To provide a consistent explanation of the different physical phenomena affecting the beam, tracking simulations have been performed and the results will be presented in this contribution. These include electron cooling and various scattering effects under realistic conditions. The effects of several imperfections in the electron cooling process will also be discussed. In addition, analytical approximations of the temporal variation of emittance under these conditions will be presented, and compared with numerical simulation results.
 
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THPAF023 The Beam Optics of the FFAG Cell of the CBETA ERL Accelerator optics, quadrupole, focusing, linac 3000
 
  • W. Lou, A.C. Bartnik, J.A. Crittenden, C.M. Gulliford, G.H. Hoffstaetter, D. Sagan
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • J.S. Berg, S.J. Brooks, F. Méot, D. Trbojevic, N. Tsoupas
    BNL, Upton, Long Island, New York, USA
  • C.E. Mayes
    SLAC, Menlo Park, California, USA
 
  Funding: This manuscript has been authored by employees of Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
The Cornell-Brookhaven Energy Recovery Linac Test Accelerator now under construction will accelerate electrons from 6 MeV to 150 MeV in four linac passes, using a single return line accepting all energies from 42 to 150 MeV. We describe the optical design of the machine, with emphasis on recent updates. We explain how we choose parameters for the wide energy acceptance return arc, taking into account 3D field maps generated from magnet designs. We give the final machine parameters resulting from iterations between desired lattice properties and magnet design. We modified the optics to improve the periodicity of the return arc near its ends and to create adequate space for vacuum hardware. The return arc is connected to the linac with splitter lines that serve to match the optics for each beam energy. We describe how matching conditions were chosen for the splitter lines and how we use them to control longitudinal motion. We simulate the injection and low energy extraction systems including space charge effects, matching the beam properties to the optical parameters of the rest of the machine.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF023  
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THPAF024 Understanding and Compensating Emittance Diluting Effects in Highly Optimized Ultrafast Electron Diffraction Beamlines emittance, space-charge, cathode, gun 3004
 
  • C. M. Pierce, I.V. Bazarov, C.M. Gulliford, J.M. Maxson
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • S. Baturin
    Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA
  • M.A. Gordon, Y.K. Kim
    University of Chicago, Chicago, Illinois, USA
 
  Funding: This work was supported by the Center for Bright Beams, NSF PHY-1549132 and Department of Energy grant DE-SC0014338.
The application of Multiobjective Genetic Algorithm optimization (MOGA) to photoemission based ultrafast electron diffraction (UED) beamlines featuring extremely low cathode mean transverse energies has lead to designs with emittances as low as 1 nm for sub-picosecond bunches with 105 electrons*. Analysis of these results shows significant emittance growth during transport: with emittance dilution as high as a factor of 200-4000% for various designs and optics settings. In this study we quantify and model the individual sources of emittance growth (slice mismatches and space charge), and explore the use of the core emittance as a strong invariant.
C. Gulliford, A. Bartnik, and I. Bazarov. Multi-
objective optimizations of a novel cryocooled dc gun based
UED beam line. Phys. Rev. Ac-
celerators and Beams, 19(9):093402, 2016.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF024  
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THPAF025 Progress in Measurement and Modeling of Electron Cloud Effects at CesrTA dipole, simulation, emittance, positron 3007
 
  • S. Poprocki, S.W. Buechele, J.A. Crittenden, D. L. Rubin
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467 and the US Department of Energy DE-FC02-08ER41538, DE-SC0006505.
The synchrotron-radiation-induced buildup of low-energy electron densities in positron and proton storage rings limits performance by causing betatron tune shifts and incoherent emittance growth. The Cornell Electron Storage Ring (CESR) Test Accelerator project includes extensive measurement and modeling programs to quantify such effects and apply the knowledge gained to the design of future accelerator projects. We report on improved measurements of betatron tune shifts along a train of positron bunches, now accurate in both horizontal and vertical planes. Improved electron cloud buildup modeling uses detailed information on photoelectron production properties obtained from recently developed simulations and successfully describes the measurements after determining ring-wide secondary-yield properties of the vacuum chamber by fitting the model to data with a multi-objective optimizer. Cloud splitting in dipole magnetic fields is seen to be the source of horizontal tune shifts decreasing at higher bunch populations.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF025  
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THPAF026 Modeling Studies for Synchrotron-Radiation-Induced Electron Production in the Vacuum Chamber Walls at CesrTA photon, simulation, vacuum, site 3011
 
  • S. Poprocki, J.A. Crittenden, D. L. Rubin, D. Sagan
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467 and the US Department of Energy DE-FC02-08ER41538, DE-SC0006505.
We report on calculations of electron production by synchrotron radiation absorbed in the vacuum chamber walls of the Cornell Electron Storage Ring (CESR). These electrons are the source of electron clouds which limit the performance of storage rings by causing betatron tune shifts, instabilities and emittance growth. Until now, cloud buildup modeling codes have used ad hoc models of the production of the seed electrons. We have employed the photon scattering code Synrad3D to quantify the pattern of absorbed photons around the CESR ring, including the transverse distribution on the wall of the beam-pipe. These distributions in absorbed photon energy and incident angle are used as input to Geant4-based simulations of electron emission from the walls. The average quantum efficiency is found to vary dramatically with the location of the absorption site, owing to the distribution in impact energies and angles. The electron production energy spectrum plays an important role in the modeling of electron cloud buildup, where the interplay of production energy and acceleration by the beam bunches determines the time structure and multipacting characteristics of the cloud.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF026  
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THPAF033 Degradation of Electron Beam Quality for a Compact Laser-Based FEL FEL, emittance, laser, space-charge 3029
 
  • A.Y. Molodozhentsev, L. Pribyl
    Czech Republic Academy of Sciences, Institute of Physics, Prague, Czech Republic
  • K.O. Kruchinin
    ELI-BEAMS, Prague, Czech Republic
 
  Laser wake field acceleration (LWFA) mechanism allows to produce extremely short electron bunches of a few fs length with the energy up to a few GeV in extremely compact geometries providing unique electron beam parameters, in particular, transverse beam emittance (order of 1pi mm mrad), extremely short bunch length and high beam charge (up to 100pC) . This novel acceleration method therefore opens a new way to develop compact 'laser-based' FELs. In the frame of this report we analyze effects, which lead to degradation of an electron beam quality. The chromatic and collective effects are analyzed for a compact dedicated electron beam line to transport the electron beam to an undulator. In addition, the SASE FEL performance has been discussed taking into consideration the degradation of the electron beam quality.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF033  
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THPAF045 Performance Optimisation of Turn-by-Turn Beam Position Monitor Data Harmonic Analysis betatron, optics, lattice, software 3064
 
  • L. Malina, J.M. Coello de Portugal, J. Dilly, P.K. Skowroński, R. Tomás, M.S. Toplis
    CERN, Geneva, Switzerland
  • J.M. Coello de Portugal
    UPC, Barcelona, Spain
 
  Nowadays, turn-by-turn beam position monitor data is increasingly utilized in many accelerators, as it allows for fast and simultaneous measurement of various optics parameters. The accurate harmonic analysis of turn-by-turn data costs beam time when needed online. Generally, the electronic noise is avoided by cleaning of the data based on singular value decomposition. In this paper, we exploit the cleaning procedure to compress the data for the harmonic analysis. This way the harmonic analysis is sped up by an order of magnitude. The impact on measurement accuracy is discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF045  
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THPAF057 Instability Observations in the Large Hadron Collider During Run 2 coupling, operation, simulation, hadron 3099
 
  • L.R. Carver, D. Amorim, S. A. Antipov, N. Biancacci, X. Buffat, G. Iadarola, K.S.B. Li, E.H. Maclean, L. Mether, E. Métral, B. Salvant, M. Schenk
    CERN, Geneva, Switzerland
  • L. Mether, M. Schenk
    EPFL, Lausanne, Switzerland
 
  Instabilities of many different types and characteristics have been observed in the LHC during Run 2. The origin of these instabilities come from a variety of stabilising and destabilising mechanisms. Efforts to understand these instabilities and prevent their occurrence has improved the performance of the LHC in all stages of the machine cycle. This paper aims to give an overview into some of the instability observations and details the operational steps to prevent them.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF057  
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THPAF058 Experimental Characterisation of a Fast Instability Linked to Losses in the 16L2 Cryogenic Half-Cell in the CERN LHC MMI, operation, monitoring, pick-up 3103
 
  • B. Salvant, S. A. Antipov, G. Arduini, N. Biancacci, X. Buffat, L.R. Carver, P. Collier, A.A. Gorzawski, W. Höfle, G. Iadarola, G. Kotzian, A. Lechner, T.E. Levens, D. Mirarchi, E. Métral, G. Rumolo, D. Valuch
    CERN, Geneva, Switzerland
  • L. Mether
    EPFL, Lausanne, Switzerland
 
  The operation during the summer months of the 2017 Run of the CERN LHC was plagued with fast beam losses that repeatedly occurred in the 16th arc half-cell at the left of IP2 as well as in the collimation insertion, leading to unwanted beam dumps. Transverse coherent oscillations were observed during this fast process. We detail here the experimental observations of coherent motion that al-lowed shedding light upon parts of the mechanism and identify the potential mitigations that were successfully implemented in the second half of the Run.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF058  
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THPAF075 Numerical Simulations of Space Charge Compensation with an Electron Lens space-charge, lattice, simulation, emittance 3154
 
  • E.G. Stern, Y.I. Alexahin, J.F. Amundson, A.V. Burov, A. Macridin, V.D. Shiltsev
    Fermilab, Batavia, Illinois, USA
 
  The future high energy physics program at Fermilab requires that the proton complex operate with beam bunch intensities four times larger than is currently handled. At these intensities space charge nonlinear defocussing effects cause unacceptable particle losses especially in the low energy rapid-cycling-synchrotron (RCS) Booster. Focusing electron lens elements may offer a solution by providing partial space charge compensation but there is a need for detailed simulations as this technique has not been demonstrated. We report on high fidelity numerical 6D space charge simulations in a model accelerator lattice with a record high space charge tune shift approaching unity.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF075  
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THPAK010 Optimization on the Optical Resonator of CTFEL FEL, GUI, radiation, coupling 3228
 
  • X.J. Shu, Y.H. Dou
    Institute of Applied Physics and Computational Mathematics, People's Republic of China
  • M. Li, Z. Xu, Y. Xu, X. Yang
    CAEP/IAE, Mianyang, Sichuan, People's Republic of China
 
  Funding: Program for the National Science Foundation of China (Grant No. 11105019) and the National Science Device Exploitation Foundation of China (Grant No. 2011YQ130018).
A high power THz free electron laser (FEL) facility is under construction at China Academy of Engineering Physics (CTFEL) since October, 2011. The radiation frequency of the FEL facility will be tuned in range of 1~3 THz and the average output power is about 10 W. The system mainly consists of a GaAs photoemission DC gun, superconductor accelerator, the hybrid wiggler, optical cavity. The first lasing is obtained on Aug. 29, 2017. The optical resonator of CTFEL is optimized to ensure wavelength tunable in a wide range and high power operation. The FEL power strongly depends on the performance of the optical resonator including output efficiency, gain and round-trip loss. The optical resonator consists of metal-coated reflect mirror, the center-hole output mirror, waveguide. The influence of waveguide and Rayleigh length on the quality of optical cavity is evaluated by the 3D-OSIFEL code. The waveguide size, mirror curvature radius, output hole radius is optimized to different frequencies between 1 THz to 3 THz.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK010  
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THPAK014 Analytical Estimation of the Beam Ion Instability in HEPS simulation, operation, brightness, damping 3231
 
  • N. Wang, Z. Duan, S.K. Tian, H.S. Xu
    IHEP, Beijing, People's Republic of China
 
  The High Energy Photon Source (HEPS) is a new designed photon source at beam energy of 6 GeV, with natural beam emittance less than 100pm. Due to the small transverse beam size, beam ion instability is one of the potential issues for HEPS. The growth time of the instability is estimated analytically for different operation scenarios. The results show considerably good agreement with the wake strong simulations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK014  
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THPAK016 Measurement and Analysis of Synchrotron Tune Variation with Beam Current in BEPCII synchrotron, cavity, positron, impedance 3237
 
  • N. Wang, Z. Duan, G. Xu, H.S. Xu, C.H. Yu, Y. Zhang
    IHEP, Beijing, People's Republic of China
 
  Coherent synchrotron frequency shift is observed during machine studies in BEPCII (Beijing Electron Positron Collider Upgrade). The results show that the synchrotron frequency varies parabolically with the increase of the beam current. This phenomenon is supposed to be induced by the interaction of the beam with the fundamental mode of the accelerating cavity. In order to explain this phenomenon, a simple physical model is developed from the couple bunch instability theory. The analytical estimations based on the physical model show good agreement with the measurements.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK016  
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THPAK032 Elaborated Modeling of Synchrotron Motion in Vlasov-Fokker-Planck Solvers simulation, synchrotron, storage-ring, damping 3283
 
  • P. Schönfeldt, T. Boltz, A. Mochihashi, A.-S. Müller, J.L. Steinmann
    KIT, Karlsruhe, Germany
 
  Funding: Funded by the German Federal Ministry of Education and Research (Grant No. 05K16VKA) & Initiative and Networking Fund of the Helmholtz Association (contract number: VH-NG-320).
Solving the Vlasov-Fokker-Planck equation is a well-tested approach to simulate dynamics of electron bunches self-interacting with their own wake-field. Typical implementations model the dynamics of a charge density in a damped harmonic oscillator, with a small perturbation due to collective effects. This description imposes some limits to the applicability: Because after a certain simulation time coherent synchrotron motion will be damped down, effectively only the incoherent motion is described. Furthermore - even though computed - the tune spread is typically masked by the use of a charge density instead of individual particles. As a consequence, some effects are not reproduced. In this contribution, we present methods that allow to consider single-particle motion, coherent synchrotron oscillation, non-linearities of the accelerating voltage, higher orders of the momentum compaction factor, as well as modulations of the accelerating voltage. We also provide exemplary studies - based on the KIT storage ring KARA (KArlsruhe Research Accelerator) - to show the potential of the methods.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK032  
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THPAK045 Summary of Beam Operation Capability at FXR LIA operation, cathode, induction, experiment 3316
 
  • Y.H. Wu, J. Ellsworth
    LLNL, Livermore, California, USA
 
  Funding: This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52- 07NA27344.
In this paper we summarize the current beam operation capability of FXR linear induc-tion accelerator (LIA) at LLNL. Experi-mental measurements for electron beam pa-rameters at different beam operations are pre-sented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK045  
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THPAK046 The Ion-Hose Instability in High-Current Multi-Pulse Induction Linacs simulation, induction, vacuum, experiment 3320
 
  • C. Ekdahl
    LANL, Los Alamos, New Mexico, USA
 
  The ion-hose instability has long been considered a danger for long-pulse, high-current electron linear induction accelerators (LIAs)*. This instability is enabled by beam-electron ionization of residual background gas in the accelerator. The space-charge of the high-energy beam ejects low-energy electrons from the ionized channel, leaving a positively-charged ion channel that attracts the electron beam. The beam can oscillate in the potential well around the channel position. Likewise, the electron beam attracts the ions, which can oscillate about the beam position. Because of the vast differences in particle mass, the oscillations are out of phase, and the amplitudes grow unstably. The number of instability e-foldings is proportional to the channel ion density*, which in turn is proportional to the background pressure and pulse length. This scaling of the instability growth was demonstrated on the long-pulse DARHT-II linear induction accelerator (LIA) at Los Alamos**. The ion-hose instability is also problematic for high-current multi-pulse LIAs, because ion recombination times are so very long at typical background pressures. Moreover, because of low ion channel ion densities, and massive ions, channel expansion is too slow to reduce the instability growth by very much. In particular, the ion channel is expected to persist and its density to increase during the 3-microsecond duration of a four-pulse burst from the 2-kA, 20-MeV Scorpius LIA now being developed. Recent simulations with an experimentally validated code that was used to predict DARHT-II growth rates have shown that the magnetic focusing field designed for Scorpius will be strong enough to inhibit ion-hose instability if the background pressure is kept below a value that is readily attainable with the present designs of induction cells and other accelerator components. Details and results of these calculations are the subject of this presentation.
*H. L. Buchanan, Phys. Fluids, vol. 30, pp. 221 - 231, 1987
**C. A. Ekdahl, et al., IEEE Trans. Plasma Sci., vol. 34, pp. 460-466, 2006
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK046  
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THPAK051 Computer Simulation of Explosive Emission Electrons Acceleration and X-ray Quantum Generation in Pulse Coaxial Diode System with Interior Anode cathode, radiation, simulation, target 3333
 
  • V.I. Rashchikov, A.A. Isaev, A.E. Shikanov, E.A. Shikanov
    MEPhI, Moscow, Russia
 
  Computer simulation of electrons from explosive emission acceleration and X-ray quantum generation in pulse coaxial diode system with interior anode, which is used in accelerating tube of compact X-ray generator* with Tesla transformer as high voltage source, was done. The results obtained allow us to choose accelerating tube diode system geometry for different running modes. Comparison of numerical results with experimental data of dose rate dependence on the distance from vacuum tube anode and energy at first circuit Tesla transformer was fulfilled.
*Patent RF N71817, 03.10.2007
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK051  
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THPAK052 Single Bunch Instabilities in FCC-ee impedance, collider, simulation, vacuum 3336
 
  • E. Belli
    Sapienza University of Rome, Rome, Italy
  • G. Castorina, M. Migliorati
    INFN-Roma1, Rome, Italy
  • G. Rumolo
    CERN, Geneva, Switzerland
  • B. Spataro, M. Zobov
    INFN/LNF, Frascati (Roma), Italy
 
  FCC-ee is a high luminosity lepton collider with a centre-of-mass energy from 91 to 365 GeV. Due to the machine parameters and pipe dimensions, collective effects due to electromagnetic fields produced by the interaction of the beam with the vacuum chamber can be one of the main limitations to the machine performance. In this frame, an impedance model is required to analyze these instabilities and to find possible solutions for their mitigation. This paper will present the contributions of specific machine components to the total impedance budget and their effects on the beam stability. Single bunch instability thresholds will be estimated in both transverse and longitudinal planes.   
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK052  
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THPAK060 Transverse-to-Longitudinal Photocathode Distribution Imaging laser, quadrupole, cathode, experiment 3361
 
  • A. Halavanau, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • W. Gai, G. Ha, J.G. Power, E.E. Wisniewski
    ANL, Argonne, Illinois, USA
  • G. Ha
    PAL, Pohang, Republic of Korea
  • P. Piot
    Fermilab, Batavia, Illinois, USA
  • G. Qiang
    TUB, Beijing, People's Republic of China
 
  In this paper, we present a tunable picosecond-scale bunch train generation technique combining a microlens array (MLA) transverse laser shaper and a transverse-to-longitudinal emittance exchange (EEX) beamline. The modulated beamlet array is formed at the photocathode with the MLA setup. The resulting patterned electron beam is accelerated to 50 MeV and transported to the entrance of the EEX setup. A quadrupole channel is used to adjust the transverse spacing of the beamlet array upstream of the EEX, thereby enabling the generation of a bunch train with tunable separation downstream of the EEX beamline. Additionally, the MLA is mounted on a rotation stage which provides additional flexibility to produce high-frequency beam density modulation downstream of the EEX. Experimental results obtained at the Argonne Wakefield Accelerator (AWA) facility are presented and compared with numerical simulations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK060  
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THPAK063 Electron Beam Pattern Rotation as a Method of Tunable Bunch Train Generation lattice, laser, HOM, experiment 3372
 
  • A. Halavanau, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • P. Piot
    Fermilab, Batavia, Illinois, USA
 
  Transversely modulated electron beams can be formed in photo injectors via microlens array (MLA) UV laser shaping technique. Micro lenses can be arranged in polygonal lattices, with resulting transverse electron beam modulation mimicking the lenses pattern. Conventionally, square MLAs are used for UV laser beam shaping, and generated electron beam patterns form square beamlet arrays. The MLA setup can be placed on a rotational mount, thereby rotating electron beam distribution. In combination with transverse-to-longitudinal emittance exchange beam line, it allows to vary beamlets horizontal projection and tune electron bunch train. In this paper, we extend the technique to the case of different MLA lattice arrangements and explore the benefits of its rotational symmetries.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK063  
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THPAK064 Theoretical Modeling of Electromagnetic Field from Electron Bunches in Periodic Wire Medium radiation, simulation, lattice, FEL 3376
 
  • S.S. Chuchurka, A.I. Benediktovitch
    BSU, Minsk, Belarus, Belarus
  • S.N. Galyamin, V.V. Vorobev
    Saint Petersburg State University, Saint Petersburg, Russia
  • A. Halavanau
    Northern Illinois University, DeKalb, Illinois, USA
 
  Funding: Work supported by the Grant from Russian Foundation for Basic Research (No. 17-52-04107).
The interaction of relativistic electrons with periodic structures results in radiation by a number of mechanisms. In case of crystals one obtains parametric X-ray radiation, its frequency is determined by distance between crystallographic planes and direction of electron beam. If instead of crystal one considers a periodic structure of metallic wires with period of the order of mm, one can expect emission of THz radiation. In the present contribution we consider theoretical approaches for modeling of the distribution of electromagnetic field from electron bunches in lattice formed by metallic wires. The analytical description is possible for the case of wires with small radius, the range of validity is checked by numerical simulations. The intensity of radiation will be significantly increased if the electrons in the bunch could radiate coherently. Two possibilities will be discussed: the prebunching of the beam and the self-modulation of the beam due to interaction with radiated field.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK064  
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THPAK071 Simulation Study of the Magnetized Electron Beam solenoid, cathode, simulation, gun 3395
 
  • S.A.K. Wijethunga, J.R. Delayen, G.A. Krafft
    ODU, Norfolk, Virginia, USA
  • J. F. Benesch, F.E. Hannon, G.A. Krafft, M.A. Mamun, M. Poelker, R. Suleiman
    JLab, Newport News, Virginia, USA
 
  Funding: This work is supported by the Department of Energy, Laboratory Directed Research and Development funding, under contract DE-AC05-06OR23177
Electron cooling of the ion beam plays an important role in electron ion colliders to obtain the required high luminosity. This cooling efficiency can be enhanced by using a magnetized electron beam, where the cooling process occurs inside a solenoid field. This paper compares the predictions of ASTRA and GPT simulations to measurements made using a DC high voltage photogun producing magnetized electron beam, related to beam size and rotation angles as a function of the photogun magnetizing solenoid and other parameters.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK071  
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THPAK074 Beam Manipulation Using Self-Induced Fields in the SwissFEL Injector wakefield, FEL, experiment, laser 3401
 
  • S. Bettoni, P. Craievich, R. Ganter, P. Heimgartner, H. Jöhri, F. Marcellini, S. Reiche
    PSI, Villigen PSI, Switzerland
 
  Several possibilities of manipulating the electron beam using sources of wakefield are being explored. Wakefield have been successfully used to remove or enhance the energy chirp residual from the magnetic compression to control the free electron laser bandwidth (dechirper), to linearize the compressed beam (linearizer), to generate more bunches to produce two color mode, and to perform experiments of wakefield acceleration. At the SwissFEL injector we plan to install 2 m long system to accommodate sources of wakefield with different periodicities, each of them associated with one of the discussed beam manipulation. In this paper we summarize the design and the characterization of the system and the planned activities.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK074  
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THPAK075 Simulation of Particle Interactions in a High Intensity Radio-Frequency Quadrupole for Molecular Hydrogen Ions rfq, proton, simulation, acceleration 3405
 
  • M.J. Easton, H.P. Li, Y.R. Lu, Z. Wang
    PKU, Beijing, People's Republic of China
  • J. Qiang
    LBNL, Berkeley, California, USA
 
  High-intensity deuteron accelerators run the risk of deuteron-deuteron interactions leading to activation. For this reason, in the commissioning phase, a molecular hydrogen ion (H2+) beam is often used as a model for the deuteron beam without the radiation risk. However, composite ions are susceptible to particle interactions that do not affect single ions, such as stripping of electrons and charge exchange. Such interactions affect the beam dynamics results, and may lead to production of secondary particles, which in high-intensity beams may cause damage to the accelerator and reduce the quality of the beam. In order to understand these effects, we have modified the IMPACT-T particle tracking code to include particle interactions during the tracking simulation through a high-intensity continuous-wave (CW) radio-frequency quadrupole (RFQ). This code is also designed to be easily extensible to other interactions, such as collisions or break-up of heavier ions. Preliminary results and possibilities for future development will be discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK075  
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THPAK111 Envelope Calculations on the Ion Beam Injection and Extraction of CANREB EBIS simulation, injection, extraction, TRIUMF 3496
 
  • M.H. Pereira-Wilson
    UW/Physics, Waterloo, Ontario, Canada
  • R.A. Baartman, S. Saminathan
    TRIUMF, Vancouver, Canada
 
  An electron beam ion source (EBIS) is being developed as a charge state breeder for the production of highly charged ions in the CANREB (CANadian Rare isotope facility with Electron Beam ion source) project at TRIUMF. The multiple tunable electrodes of the EBIS, coupled with the necessity of directing both an electron beam and an ion beam of varying charge, impose a challenging task for the optimization of the beam optics. With this in mind, beam envelope simulations have been performed to determine the acceptance of the EBIS and the emittance of the extracted ion beam. The electric field of the different EBIS electrodes were modelled using finite element analysis software and the envelope simulations were executed using beam envelope code TRANSOPTR. Preliminary results show envelope calculation as a viable candidate for tuning the injection and extraction optics of the EBIS.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK111  
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THPAK114 Evaluation of an Interior Point Method Specialized in Solving Constrained Convex Optimization Problems for Orbit Correction at the Electron Storage Ring at DELTA software, feedback, storage-ring, closed-orbit 3507
 
  • S. Koetter, A. Glaßl, B.D. Isbarn, D. Rohde, M. Sommer, T. Weis
    DELTA, Dortmund, Germany
 
  The slow orbit feedback at the electron storage ring at DELTA will be upgraded with new software. Finding a set of dipole-field-strength variations which minimize the deviation of the orbit from a reference orbit requires solving a convex optimization problem subject to inequality constraints. This work focuses on exploiting properties of a special type of interior point methods, which can solve this problem, for orbit correction at DELTA. After comparing runtimes of an interior point method to a Newton-like optimization algorithm, the performance of the new slow-orbit-feedback software is assessed based on measurement results.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK114  
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THPAK116 Modeling Surface Roughness Effects and Emission Properties of Bulk and Layered Metallic Photocathode simulation, emittance, experiment, cathode 3515
 
  • D.A. Dimitrov, G.I. Bell
    Tech-X, Boulder, Colorado, USA
  • I. Ben-Zvi, J. Smedley
    BNL, Upton, Long Island, New York, USA
  • J. Feng, S.S. Karkare, H.A. Padmore
    LBNL, Berkeley, California, USA
 
  Funding: This work was supported by the Office of Science, Office of Basic Energy Sciences of the U.S. Department of Energy under Contract Nos. DE-SC0013190, DE-AC02-05CH11231, and KC0407-ALSJNT-I0013.
The thermal limit of the intrinsic emittance of photocathodes represents an important property to measure experimentally and to understand theoretically. Detailed measurements of intrinsic emittance have become possible in momentatron experiments. Moreover, recent developments in material design have allowed growing photoemissive layers with controlled surface roughness. Although analytical formulations of the effects of roughness have been developed, a full theoretical model and experimental verification are lacking. We aim to bridge this gap by developing realistic models for different materials in the three-dimensional VSim particle-in-cell code. We have recently implemented modeling of electron photo-excitation, transport, and emission from photoemissive layers grown on a substrate. We report results from simulations with these models on electron emission from antimony and gold. We consider effects due to density of states, photoemissive layer thickness, surface roughness and how they affect the spectral response of quantum yield and intrinsic emittance.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK116  
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THPAK122 Longitudinal Coupled Bunch Instability in JLEIC HOM, cavity, impedance, resonance 3530
 
  • R. Li, J. Guo, F. Marhauser, S. Wang
    JLab, Newport News, Virginia, USA
 
  Funding: This work is supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The luminosity performance of the JLEIC design is achieved by using a high bunch repetition rate (476MHz) with moderate bunch charges, similar to the strategy employed in modern lepton colliders. Such a bunch configuration will make single bunch instabilities less probable, yet makes the machine more prone to the onset of longitudinal and transverse coupled bunch instabilities. Consequently, this will set higher demands on the bunch-by-bunch feedback systems to mitigate the multi-bunch instabilities. In this paper we present our detailed analysis of the growth rate of the coupled bunch instabilities for beams in both the electron and ion rings in JLEIC at the collision scenario. The implication of the growth rate on the feedback system will be discussed.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK122  
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THPAK123 Updates on Collective Effects Estimations for JLEIC impedance, cavity, collider, luminosity 3533
 
  • R. Li, K. E. Deitrick, T.J. Michalski
    JLab, Newport News, Virginia, USA
 
  Funding: This work is supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
JLEIC is the high luminosity and high polarization electron-ion collider (EIC) currently under active design at Jefferson Lab. It aims at high luminosity (1033~1034 cm-2s−1) for a wide range of ion species and center-of-mass energies. This luminosity performance relies sensibly on beam stability with high intensity electron and ion beam operation. The impedance budget analysis and the estimations of the single and multibunch instabilities are currently underway. In this paper, we present the update status of estimations for the longitudinal and transverse coherent instabilities, and identify areas or parameter regimes where special attentions for instability mitigations are required.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK123  
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THPAK127 Toroidal Merger Simulations for the JLEIC Bunched Beam Electron Cooler Ring emittance, solenoid, space-charge, simulation 3540
 
  • A.V. Sy
    JLab, Newport News, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The bunched beam electron cooler ring for the Jefferson Lab Electron-Ion Collider (JLEIC) requires a merger system to transport magnetized electron beams of two different energies to the same energy recovery linac (ERL) beamline. The system is especially challenging compared to existing mergers for ERL or hadron cooling applications (as at COSY) due to the small separation in energy between the two beams; for the JLEIC bunched beam cooler, the two beam energies may only differ by a factor of 4. An additional complication is the use of a magnetized beam. A toroidal merger system is studied using G4Beamline/GEANT4. Preservation of the quality of the low energy beam from the injector is especially vital for efficient cooling performance and compatibility with the ERL. Effects of the toroidal system on transverse and longitudinal emittances of the magnetized beams, as well as space charge effects, are presented and discussed.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK127  
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THPAK129 Modeling Challenges for Energy Recovery Linacs With Long, High Charge Bunches bunching, space-charge, recirculation, lattice 3544
 
  • C. Tennant
    JLab, Newport News, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Historically, nearly all energy recovery linacs (ERLs) built and operated were used to drive a free-electron laser (FEL). The requirement for high peak current bunches necessitates bunch compression and handling the attendant beam dynamical challenges. In recent years, ERLs have turned from being drivers of light sources toward applications for nuclear physics experiments, Compton backscattering sources and strong electron cooling. Unlike an FEL, these latter uses require long, high charge bunches with small energy spread. The electron bunch must maintain a small projected energy spread and therefore must avoid gross distortion due to CSR and longitudinal space charge over a single (or multiple) recirculations. Accurately modeling the relevant collective effects in the system 'space charge, microbunching instability, CSR and the effect of shielding' in addition to beam dynamical processes such as halo, presents a formidable challenge. Absent a code that models all of these effects, we outline an approach towards the design, analysis and optimization of the high-energy electron cooler for the Jefferson Lab Electron-Ion Collider and survey widely used codes and their capabilities.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK129  
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THPAK131 Investigation of Two-Bunch Train Compression by Velocity Bunching bunching, cavity, emittance, experiment 3548
 
  • D. Wang, Y. C. Du, W.-H. Huang, X. Liu, X.L. Su, C.-X. Tang, Q.L. Tian, L.X. Yan
    TUB, Beijing, People's Republic of China
  • H. Zhang
    Tsinghua University, Beijing, People's Republic of China
 
  Two electron beamlets, also referred as two-bunch train with adjustable time and energy spacing are popular in many applications such as two color FEL and pump-probe experiments. We investigate compression of two-bunch train via velocity bunching scheme in a traveling wave accelerator (TWA) tube by varying the phase of TWA tube in a very large range. Beam dynamics simulations show that when the phase injected into the accelerator tube for the beam is set to ≪-100 degree, velocity bunching occurs in a deep over-compression mode, where two-bunch train is continuously tunable in time and in energy space, and the emittance of each sub-bunch is also preserved. In the experiment, we use energy spectrum and defecting cavity to diagnose the train's energy space and time space respectively, the measurements demonstrated that two-bunch train through deep over-compression scheme is separated both in time and in energy space, which also agree well with the predictions.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK131  
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THPAK136 Wide-Ranging Genetic Research of Matching Line Design for Plasma Accelerated Beams with GIOTTO plasma, emittance, target, FEL 3561
 
  • M. Rossetti Conti
    Universita' degli Studi di Milano & INFN, Milano, Italy
  • A. Bacci, A.R. Rossi
    Istituto Nazionale di Fisica Nucleare, Milano, Italy
  • A. Giribono, C. Vaccarezza
    INFN/LNF, Frascati (Roma), Italy
 
  GIOTTO is a code based on a Genetic Algorithm, being used in the field of particles accelerators for some years*-***. Its main use concerns beam-dynamics optimizations for low energy linacs, or injectors, where the beam space-charge plays an important role on its dynamics. Typical optimizations regard the Velocity Bunching technique or, more generally, the emittance and energy spread minimization. Recent improvements in GIOTTO, here discussed, have added the important capability to solve problems with a wide research domain, making GIOTTO able to design a beam Transfer Line (TL) from scratch****. The code, taking as input the TL length and the optics elements, can define the correct lattice of the line that transports and matches the beam from the linac to the undulators of an FEL, finding the right gradients, positions and dimensions for the optics elements by exploring the parameters values in selected ranges. Further, the introduction of Twiss parameters into the fitness function makes GIOTTO a powerful tool in the design of highly different beam lines. Lastly, a new routine for the statistical analysis of parameters jitters effects on the beam is under development.
*Bacci et al, NIM-B, 263, 488 (2007)
**Bacci et al, presented at PAC'07, THPAN031
***Bacci et al, presented at IPAC'16, WEPOY039
****Rossetti Conti et al, NIM-A (2018, in press)
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK136  
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THPAK138 Development of Efficient Tree-Based Computation Methods for the Simulation of Beam Dynamics in Sparsely Populated Phase Spaces simulation, FEL, bunching, HOM 3569
 
  • Ph. Amstutz
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • M. Vogt
    DESY, Hamburg, Germany
 
  Collective instabilities pose a major threat to the quality of the high brightness electron beams needed for the operation of a free electron laser. Multi-stage bunch compression schemes have been identified as a possible source of such an instability. The dispersive sections in these compressors translate energy inhomogeneities within the bunch into longitudinal charge density inhomogeneities. In conjunction with a collective force driving locally density-dependent energy modulations this leads to intricate longitudinal beam dynamics. As a consequence of the thin shape those bunches form in the longitudinal phase space, efficient simulation of such systems is not straight forward. At high resolutions, the numerical representation of the phase space density on a uniform grid is too wasteful, due to the large unpopulated phase space regions. In this contribution we present advances made in the development of a simulation code that addresses the problem of sparsely populated phase spaces by means of quadtree domain decomposition. A focus lies on the explanation of the underlying tree data structure.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK138  
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THPAK140 Pyroelectric Detection of Coherent Radiation on the CLARA Phase 1 Beamline radiation, dipole, detector, simulation 3577
 
  • B.S. Kyle
    University of Manchester, Manchester, United Kingdom
  • R.B. Appleby, T.H. Pacey
    UMAN, Manchester, United Kingdom
  • P.H. Williams
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • J. Wolfenden
    The University of Liverpool, Liverpool, United Kingdom
 
  The impacts of coherent synchrotron radiation (CSR) and space charge in the bunch compressor section of the CLARA Free Electron Laser (FEL) are expected to be significant, given the relatively high charge and short bunch lengths expected. The General Particle Tracer (GPT) code allows for the modelling of these effects in tandem, presenting an opportunity to more reliably estimate their effects on the CLARA beam. To provide confidence in future studies using GPT, a benchmarking study on the CLARA Phase 1 beamline is presented alongside relevant simulations. This study will make use of pyroelectric detectors to measure the emitted coherent power of the CLARA beam as it passes through a dispersive section whilst varying the chirp imparted on the bunches longitudinal phase space (LPS). Simulations presented demonstrate the viability of such a study, with energies between ∼ 10-100 nJ per pulse expected to be incident upon the detector face.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK140  
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THPAK141 Initial Tests of Nonlinear Quasi-Integrable Optics at the University of Maryland Electron Ring octupole, optics, experiment, simulation 3581
 
  • H. Baumgartner, B.L. Beaudoin, I. Haber, T.W. Koeth, D.B. Matthew, K.J. Ruisard
    UMD, College Park, Maryland, USA
 
  Funding: Funding for this project and travel is provided by DOE-HEP, NSF GRFP and NSF Accelerator Science Program.
An octupole channel has been inserted into the University of Maryland Electron Ring (UMER), in order to investigate the mitigation of destructive resonances as a novel approach in high-intensity beam transport. The individual octupole magnets have been characterized using our in-house 3-dimensional magnet mapping stage, with a measured gradient of 51.6 ± 1.5 T/m3/A. A single section (20°) of an 18-cell FODO lattice has been replaced by a longitudinally-varying octupole channel constructed from seven flexible printed circuits (PCBs). We present the design of the channel and preliminary beam based measurements on the ring.
 
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THPAK144 A Pseudospectral Method for Solving the Bloch Equations of the Polarization Density in e- Storage Rings polarization, storage-ring, ion-effects, synchrotron 3589
 
  • K.A. Heinemann, O. Beznosov, J.A. Ellison
    UNM, Albuquerque, New Mexico, USA
  • D. Appelö
    University of Colorado at Boulder, Boulder, USA
  • D.P. Barber
    DESY, Hamburg, Germany
 
  Funding: Work supported by DOE under DE-SC0018008
We consider the numerical evolution of Bloch equations for the polarization density in high-energy electron storage rings. Equilibrium polarization is well characterized by the DK formulas for current rings, but deviations may be important at the high energies we have in mind. We believe the Bloch equations derived in* give a more accurate description at all energies. These form a system of three coupled linear partial differential equations for the three components of the polarization density. Following** we formulate the equations in action-angle variables and approximate the Fokker-Planck terms. We aim to integrate these equations numerically in order to approximate the equilibrium and compare with the DK formulas. The smoothness and simple geometry of the problem makes it amenable to pseudospectral discretization using Fourier modes in the angles and Chebyshev polynomials in the actions, leading to a large ODE system. We will explore time stepping algorithms for the needed long time integration. Here, we present results for simple models checking the accuracy of the numerical method but note that our ultimate goal is to simulate polarization in the FCC and CEPC rings.
* Ya.S.Derbenev, A.M.Kondratenko, Sov. Phys. Dokl., 19, p.438 (1975).
** D.P.Barber, K.Heinemann, H.Mais, G.Ripken,
A Fokker-Planck treatment of stochastic particle motion…,
DESY-91-146, 1991.
 
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THPAK152 Study of GF Symplectic Tracking Method and Compensation for the EPU104 at the HLS-II undulator, dynamic-aperture, synchrotron, synchrotron-radiation 3603
 
  • Z.H. Yang, Z.H. Bai, W. Li, G. Liu, L. Wang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  An elliptically polarized undulator (EPU) was applied to obtain high-brightness coherent synchrotron radiation at the upgraded Hefei Light Source, HLS-II. However, the EPU has serious dynamic effects on the beam performances including close orbit, emittance and dynamic aperture etc. when installed at the storage ring. In order to understand the effects, a Taylor expanded generating method was adopted to generate a fast and symplectic map for particle tracking. As for the compensation of the EPU, striplines were equipped above and below the vacuum chamber to reduce the nonlinear effects. With the symplectic tracking routine and the surface fitting method, different parameters such as dynamic aperture and the driving terms, could be set as the objective function to accomplish the optimization of the EPU.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK152  
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THPAK154 Beam Parameter Optimization for UEM Facility with Photo-Emission S-band RF Gun gun, space-charge, laser, emittance 3610
 
  • H.R. Lee, P. Buaphad, Y. Joo
    University of Science and Technology of Korea (UST), Daejeon, Republic of Korea
  • S.C. Cha, Y. Kim
    KAERI, Daejon, Republic of Korea
  • B.L. Cho
    KRISS, Daejeon, Republic of Korea
  • H. Suk
    GIST, Gwangju, Republic of Korea
 
  Ultrafast Electron Microscopy (UEM) can provide snapshot images of a dynamic process in samples with an ultrafast time resolution, which is shorter than picosecond. The Future Accelerator R&D Team at KAERI has been preparing a UEM facility with a photo-emission S-band (= 2856 MHz) RF gun by collaborating with GIST and KRISS. To achieve a higher spatial resolution as well as a higher time resolution, the transverse beam emittance, beam divergence, and energy spread should be smaller, and the bunch length should be shorter. Beam dynamics simulations with ASTRA code is used to optimize those beam parameters in the RF gun. In this paper, we describe ASTRA optimizations of the S-band RF gun to achieve high spatial-temporal resolutions for the UEM facility.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK154  
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THPAL010 Sector DC Dipoles Design for the Beam Test Facility Upgrade dipole, linac, quadrupole, experiment 3634
 
  • A. Vannozzi, S. Lauciani, L. Pellegrino, L. Sabbatini, C. Sanelli, G. Sensolini
    INFN/LNF, Frascati (Roma), Italy
  • P. Valente
    INFN-Roma, Roma, Italy
 
  The Beam Test Facility is part of the DAΦNE accelerators system of INFN Frascati National Laboratory. It is a transfer-line optimized for electrons and positrons extracted from the DAΦNE LINAC. An upgrade of the line is scheduled for two purposes: reach a beam energy of 920 MeV (with respect to the actual 750 MeV) and add a new branch to the present transfer line. This new layout foresees six new quadrupoles one fast ramped dipole, two H-shape and one C-shape sector dipoles. The design of the magnets has been completely performed at INFN involving Electromechanical Enterprise partner in the design phase in order to optimise the manufacturing process. This effort lead to a complete set of detailed CAD drawings that can be directly used by manufacturer to build the magnets. The goal is to boost the manufacturing of prototypes and small series from Small and Medium Enterprises. Magnetic measurements will be performed at INFN. This poster is focused on the realization of the two full iron yoke H-shape and C-shape dipoles, respectively with 45 and 15 bending angle. They are characterized by a high flux density of 1.7 T in a gap of 35 mm. They have a bending radius of 1.8 m  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL010  
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THPAL011 Fast Ramped Dipole and DC Quadrupoles Design for the Beam Test Facility Upgrade dipole, quadrupole, linac, positron 3638
 
  • L. Sabbatini, E. Di Pasquale, L. Pellegrino, C. Sanelli, G. Sensolini
    INFN/LNF, Frascati (Roma), Italy
  • P. Valente
    INFN-Roma, Roma, Italy
  • A. Vannozzi
    Sapienza University of Rome, Rome, Italy
 
  The Beam Test Facility (BTF) is part of the DAΦNE accelerators system of INFN Frascati National Laboratory. It is a transfer-line optimized for electrons and positrons extracted from the DAΦNE LINAC. An upgrade of the line is planned in order to reach a beam energy of 920 MeV (with respect to the present 750 MeV), adding a new branch to the present transfer line. The design of the magnets for this new layout has been completely performed at INFN, including electromagnetic, mechanical, thermal and hydraulic aspects. This effort lead to a complete set of detailed CAD drawings that can be used by Industrial partners to build the magnets. The manufacturing processes have been studied in detail: the goal is to boost the manufacturing of prototypes and small series from Small and Medium Enterprises. Magnetic measurements will be performed at our Institute. In this report we describe two types of magnets for this project. The first magnet is a C-shape fast ramped dipole, designed for a beam deflection of 15 degrees; the rise time is 100ms, the gap is 25mm with a magnetic field of 1.11 T. The second is a family of seven quadrupoles with a gradient of 20 T/m and a bore of 45mm.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL011  
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THPAL033 Measurement of the Internal Dark Current in a High Gradient Accelerator Structure at 17 GHz multipactoring, acceleration, experiment, simulation 3705
 
  • H. Xu, M.A. Shapiro, R.J. Temkin
    MIT/PSFC, Cambridge, Massachusetts, USA
 
  Funding: Work supported by the U.S. Department of Energy, Office of High Energy Physics, under Grant No. DE-SC0015566
We report a study of internal dark current generation by multipactor inside a 17 GHz single cell standing wave disk-loaded waveguide accelerator structure. The multipactor takes place on the side wall of the central cell, driven by the local rf electric and magnetic fields. Theory indicates that a resonant multipactor mode with two rf cycles can be excited near 45 MV/m gradient and a single rf cycle multipactor mode near 60 MV/m. The accelerator structure had two thin slits opened on the side wall of the central cell to directly extract and measure the internal dark current. The dark current was measured as a function of the gradient up to a gradient of 70 MV/m. The experimental results agreed well with theory, showing the two predicted multipactor modes. To further study the effect of the central cell side wall surface properties on the structure performance, we prepared and tested a second structure with the central cell side wall coated with a layer of diamond-like carbon. The comparison of the results showed that the coating reduced the internal dark current and thus enhanced the structure performance considerably.
 
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THPAL037 Nano-engineering of Nb3Sn Thin Films to Improve Wire Performance and Reduce Cost collider, lattice, coupling, dipole 3720
 
  • S.A. Kahn, M.A. Cummings
    Muons, Inc, Illinois, USA
  • E.Z. Barzi
    Fermilab, Batavia, Illinois, USA
 
  State-of-the-art Nb3Sn wires have plateaued in the performance of the critical current density Jc. Chemical and geometrical optimization of the wire layout have produced Nb3Sn wires with average Jc(4.2K, 16T) ~ 1,300 A/mm2. A future high energy hadron collider that is being considered to follow the LHC would need larger Jc and be cost effective. The approach to improving the performance of Nb3Sn conductor would be to introduce enhanced flux pinning mechanisms with nano-engineering techniques.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL037  
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THPAL038 Phase Grouping of Larmor Electrons by a Synchronous Wave in Controlled Magnetrons controls, cavity, operation, cathode 3723
 
  • G.M. Kazakevich, R.P. Johnson
    Muons, Inc, Illinois, USA
  • V.A. Lebedev, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
 
  A simplified analytical model based on the charge drift approximation has been developed. It considers the resonant interaction of the synchronous wave with the flow of Larmor electrons in a magnetron. The model predicts stable coherent generation of the tube above and below the threshold of self-excitation. This occurs if the magnetron is driven by a sufficient resonant injected signal (up to -10 dB). The model substantiates precise stability, high efficiency and low noise at the range of the magnetron power control over 10 dB by variation of the magnetron current. The model and the verifying experiments with 2.45 GHz, 1 kW magnetrons are discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL038  
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THPAL043 Dipole Magnets for the Technological Electron Accelerators dipole, permanent-magnet, radiation, simulation 3739
 
  • I.S. Guk, O.M. Bovda, V.O. Bovda, A.N. Dovbnya, S.G. Kononenko, V.N. Ljashchenko, A. Mytsykov, L.V. Onishchenko, A.Y. Zelinsky
    NSC/KIPT, Kharkov, Ukraine
 
  Permanent magnets made of rare earth elements alloys allow to develop compact dipole magnets for the applied electron accelerator. These devices can be used for the beam trajectory bending as well as for the beam characteristics measurements. For NSC KIPT linear accelerator «EPOS» a dipole magnet on the base of Nd-Fe-B alloy has been designed and developed. The magnet provides 90 degrees bend of 23 MeV electron beam. The design value of magnetic field at the beam design trajectory is 0.5 Т. The magnet effective length is 242 mm. The magnet temperature can be changed with thermos-stabilization system. For NSC KIPT 10 MeV LU-10 applied accelerator a dipole magnet of Sm2Co17 alloy has been manufactured. The maximum magnet field of the magnet is 0.3 Т. The magnet layout allows easy magnet assembling at the accelerator chamber. The magnet is used for the beam energy measurement and accelerator beam energy turning. After energy turning the magnet should be removed from the accelerator lattice.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL043  
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THPAL044 The Permanent Magnets Magnetic Characteristics Change Under Effect of 10 MeV Beam radiation, experiment, permanent-magnet, ECR 3742
 
  • I.S. Guk, O.M. Bovda, V.O. Bovda, A.N. Dovbnya, A.I. Kalinichenko, S.S. Kandybey, V.N. Ljashchenko, A. Mytsykov, L.V. Onishchenko, O.A. Repikhov, A.Y. Zelinsky
    NSC/KIPT, Kharkov, Ukraine
 
  Magnets of applied electron accelerators are under direct effect of electrons and bremsstrahlung radiation stipulated by the electron beam. The choice of the materials for the rare elements alloy accelerator magnets has the decisive importance for the long term magnet parameters keeping. The experimental studies of the magnetic fields around the Nd-Fe-B and Sm2Co17 alloy magnets under effect of the electron beam have been done. The samples of 30х24х12 mm geometrical sizes were bombarded by electron beam of applied NSC KIPT accelerator KUT-1 with electron energy of 10 MeV and were irradiated by correspondent bremsstrahlung. The magnetic field value around Nd-Fe-B alloy samples was decreased nonlineary under electron beam bombarding with change of irradiation doze from 16 to 160 GRad. Under effect of bremsstrahlung the magnetic field value around samples was not changed. The repeated sample magnetizations allowed to restore the initial magnetic field distribution around magnets. The magnetic field distribution around Sm2Co17 alloy samples was not changed under effect of the electron beam and bremsstrahlung within irradiation dozes mentioned above. The induced activity in the Nd-Fe-B and Sm2Co17 alloy samples was changed slightly during the experiments.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL044  
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THPAL045 Determination of the Electron Bunch Length With Third Harmonic Cavity for the Taiwan Photon Source cavity, operation, simulation, SRF 3745
 
  • Z.K. Liu, F.Y. Chang, L.-H. Chang, M.H. Chang, S.W. Chang, L.J. Chen, F.-T. Chung, M.-C. Lin, C.H. Lo, Ch. Wang, M.-S. Yeh, T.-C. Yu
    NSRRC, Hsinchu, Taiwan
 
  The Taiwan Photon Source (TPS) is a modern 3 GeV low emittance light source with RMS bunch lengths of about 3 mm at a beam current of 500 mA and operating gap voltage of 3.2 MV. With a higher harmonic cavity, we could increase the Touschek lifetime and lower the heat load of in-vacuum undulators by lengthening the bunch lengths. Preliminary studies show that for full and uni-form fill patterns, the bunch lengths could be increased by a factor of four. However, this calculation ignores phase transient effects and may overestimate the effect of harmonic cavities. A multi-bunch, multi-particle tracking method has been developed to determine the bunch lengths for non-uniform fill patterns, which also takes phase transient effects into account and the expected maximum bunch lengthening factor for different TPS operation conditions are discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL045  
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THPAL049 Power Supply Decoupling Design controls, power-supply, coupling, simulation 3751
 
  • Y.T. Li, F.Y. Chang
    NSRRC, Hsinchu, Taiwan
 
  After an actual operation of the phase-shifted magnet's power supply was conducted, it was found that the currents in the two modules of magnets would be coupled each other. In order to solve this mutual coupling current, a decoupling controller is designed. From the experiment results indicate that it does not only solve the issue of coupling current but also shorten the rising time of the power supply current. This helps to increase the power supply bandwidth.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL049  
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THPAL053 Perveance Measurement of the TLS-Linac Klystron and the Evaluation of Its Operation Performance klystron, operation, cathode, linac 3763
 
  • H.H. Chen, C.H. Kuo, K.-K. Lin, Y.-H. Liu
    NSRRC, Hsinchu, Taiwan
 
  The high power klystron is a radio frequency amplifier for TLS linac operation. It is a crucial device for electron acceleration in linac. How to evaluate its efficiency, lifetime and performance of klystron in operation is one of the major concern in this report. The key klystron parameter perveance is introduced and used for performance evaluation and operation status monitoring. It is important to execute periodic monitoring on perveance for ensuring a stable linac operation. Klystron characteristics diagnostics can be achieved through perveance measurement. A couple of klystron diagnostic parameters concerning perveance are explored for field examination purpose. Perveance comparison with factory acceptance test data is also presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL053  
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THPAL068 Status of the Polarix-TDS Project FEL, undulator, status, klystron 3808
 
  • P. Craievich, M. Bopp, H.-H. Braun, R. Ganter, T. Kleeb, M. Pedrozzi, E. Prat, S. Reiche, R. Zennaro
    PSI, Villigen PSI, Switzerland
  • R.W. Aßmann, F. Christie, R.T.P. D'Arcy, U. Dorda, M. Foese, P. González Caminal, M. Hoffmann, M. Hüning, R. Jonas, O. Krebs, S. Lederer, V. Libov, B. Marchetti, D. Marx, J. Osterhoff, F. Poblotzki, M. Reukauff, H. Schlarb, S. Schreiber, G. Tews, M. Vogt, A. Wagner
    DESY, Hamburg, Germany
  • N. Catalán Lasheras, A. Grudiev, G. McMonagle, W. Wuensch
    CERN, Geneva, Switzerland
 
  A collaboration between DESY, PSI and CERN has been established to develop and build an advanced modular X-band transverse deflection structure (TDS) system with the new feature of providing variable polarization of the deflecting force. This innovative CERN design requires very high manufacturing precision to guarantee highest azimuthal symmetry of the structure to avoid the deterioration of the polarization of the streaking field. Therefore, the high-precision tuning-free production process developed at PSI for the C-band and X-band accelerating structures will be used for the manufacturing. We summarize in this paper the status of the production of the prototype and the waveguide networks foreseen in the different facilities.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL068  
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THPAL074 Numerical Studies of Normal Conducting Deflecting Cavity Designs for the ELBE Accelerator cavity, HOM, experiment, impedance 3824
 
  • T.G. Hallilingaiah, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  • A. Arnold, U. Lehnert, P. Michel
    HZDR, Dresden, Germany
 
  Currently, in the electron linac ELBE there is a single beam line. Therefore, at any given time only single user can use the beam. Moreover, as different user experiments require distinct beam intensity settings, not all the experiments fully utilize the 13 MHz CW beam capability of the facility. To utilize the full beam capacity, multiple beam lines can be established by using an array of transverse deflecting structures. For that, an RF cavity was the design choice due to its inherent advantages with respect to repeatability of the kick voltage amplitude and phase, and the possibility of CW operation in the MHz range. Potential design candidates are the CEBAF RF separator, the three proposed crab cavities for the HL-LHC upgrade project, and a novel NC deflecting cavity design. In this comparative study, the figures of merit of the cavities are computed from electromagnetic field simulations for a transverse voltage of 300 kV. This comparative study supported our selection of the deflecting cavity design for ELBE.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL074  
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THPAL081 A 3 GHz SRF Reduced-beta Cavity for the S-DALINAC cavity, linac, SRF, operation 3838
 
  • D.B. Bazyl, H. De Gersem, W.F.O. Müller
    TEMF, TU Darmstadt, Darmstadt, Germany
  • J. Enders, S. Weih
    TU Darmstadt, Darmstadt, Germany
 
  Funding: Work supported by DFG through GRK 2128
In order to reduce the energy spread and to be able to use a 200 keV spin-polarized electron source, the initial part of the injector linac of the superconducting Darmstadt electron linear accelerator S-DALINAC needs to be upgraded. The decisions on the cavity type, number of cells and value of geometric beta are motivated. The main part of this work is dedicated to the mechanical design of the cavity. A precise evaluation of the mechanical characteristics of an SRF cavity is necessary during the design stage. The dependence of the resonant frequency of the fundamental mode on external mechanical loads needs to be investigated for developing the tuning procedures. The results of the multiphysics simulations and of the optimization of the mechanical design are presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL081  
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THPAL095 Metal Photocathodes Preparation for Compact Linear Accelerator at Daresbury Laboratory plasma, cathode, gun, laser 3865
 
  • A.N. Hannah, J.A. Conlon, L.B. Jones, B.L. Militsyn, T.C.Q. Noakes, R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • V. R. Dhanak
    The University of Liverpool, Liverpool, United Kingdom
  • L.B. Jones, B.L. Militsyn
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • S. Lederer
    DESY Zeuthen, Zeuthen, Germany
  • S. Lederer
    DESY, Hamburg, Germany
 
  The photoinjector of the CLARA FEL test facility Front End at Daresbury Laboratory is based on a S-band 10 Hz photocathode RF-gun operating with a copper photocath-ode which is driven by the third harmonic of a Ti:Sapphire laser (266 nm). The main aim of this study was to establish a procedure to prepare the Cu surface prior to installation so a Quantum Efficiency (QE) of 10-5 or higher can be achieved at laser power density below the ablation threshold of copper. The best results have been obtained by ex-situ chemical cleaning. This removed the surface oxide layer whilst at the same time producing a surface buffer layer. This inhibited the regrowth of native oxide for up to a week when exposed to normal ambient atmospheric conditions. With either chemical cleaning or Ar plasma cleaning after heating the sample in-situ to 150 °C for 90 minutes or 250 °C for 40 hours, almost all of the surface oxide was removed. For these surfaces a QE of 4.10-5 or better was measured. Oxygen plasma cleaning at 100% and 20% power produced CuO layer with surface carbon contaminant to 3 atomic %, however in-situ thermal cycling resulted in at best a QE of 3·10-6.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL095  
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THPAL107 Three Years of Operational Experience With the Solaris Vacuum System vacuum, storage-ring, MMI, synchrotron 3888
 
  • A.M. Marendziak, M. Rozwadowski, T. Sobol, M.J. Stankiewicz, A.I. Wawrzyniak
    Solaris National Synchrotron Radiation Centre, Jagiellonian University, Kraków, Poland
 
  Solaris, a 1.5 GeV third generation synchrotron light source, was commissioned in 2016 April and is currently operated in decay mode. Two beamlines PEEM/XAS and UARPES were installed and now are being commis-sioned. Three more PHELIX, XMCD and diagnostic beamlines have received funding and will be installed and commissioned in next few years. With total accumu-lated beam dose near to 690 A.h and three orders of mag-nitude reduction of outgassing the design goal of 500 mA beam current and electron energy of 1.5 GeV has been achieved. As the beam current was increased, a few vacu-um problems were encountered, including vacuum leaks in RF and arc sectors and unexpected pressure bursts near photon absorbers. Lessons learned and operational expe-rience will be presented and discussed in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL107  
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THPAL133 LASE Surfaces for Mitigation of Electron Cloud in Accelerators laser, vacuum, cavity, experiment 3958
 
  • B.S. Sian
    UMAN, Manchester, United Kingdom
  • O.B. Malyshev, R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
 
  Vacuum chamber surface characteristics such as the photon and secondary electron yields (PEY and SEY) are critical parameters in the formation of an electron cloud, a serious problem that limits the performance of proton and positron accelerators. A few years ago it was discovered by the Vacuum Solutions Group at Daresbury laboratory that Laser Ablation Surface Engineering (LASE) could provide surfaces with SEY<1 [1,2]. The LASE surfaces are considered as a baseline solution for electron cloud miti-gation in the Future Circular Collider (FCC). However, these surfaces are undergoing further optimisation for the FCC application. While keeping SEY<1 the surfaces should meet the following criteria: Low outgassing, Low particulate generation and low surface resistance. In this paper we will report a number of new surfaces created using the LASE technique with different laser parameters (wavelength, scan speed, pitch, repetition rate, power, and pulse length) and their effect on the SEY, surface re-sistance and vacuum properties, etc  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL133  
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THPAL144 952.6 MHz SRF Cavity Development for JLEIC cavity, HOM, damping, SRF 3982
 
  • R.A. Rimmer, W.A. Clemens, F. Fors, J. Guo, F.E. Hannon, J. Henry, F. Marhauser, L. Turlington, H. Wang, S. Wang
    JLab, Newport News, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
JLab is developing new SRF cavity designs at 952.6 MHz for the proposed Jefferson Lab Electron-Ion Collider (JLEIC). New cavities will be required for the ion ring, cooler ERL and booster and eventually for an upgrade of the electron ring to allow the highest possible bunch collision rate. The challenges include the need for high fundamental mode power couplers and strong HOM damping, with high HOM power capability. Initial focus is on the cooler ERL 5-cell cavity as this is a critical component for the strong, high energy, bunched-beam cooling concept. 1-cell and 5-cell Nb prototype cavities have been designed and fabricated. Details concerning the cavity fabrication and test results will be presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL144  
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THPAL146 802 MHz ERL Cavity Design and Development cavity, SRF, collider, hadron 3990
 
  • F. Marhauser, S. Castagnola, W.A. Clemens, J.G. Dail, P. Dhakal, F. Fors, J. Henry, R.A. Rimmer, L. Turlington, R.S. Williams
    JLab, Newport News, Virginia, USA
  • R. Calaga, K.M. Dr. Schirm, E. Jensen
    CERN, Geneva, Switzerland
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177, and CERN Contract NR. KE3080/ATS
In the framework of a collaboration between CERN and JLab, an SRF accelerating cavity for energy recovery linacs operating at 802 MHz was developed in the context of the CERN's Large Hadron electron Collider (LHeC) design study. A single-cell and a five-cell cavity from fine grain high RRR niobium were built at JLab to validate the basic RF design in vertical tests. Two copper single-cell cavities were produced in parallel for R&D purposes at CERN. The cavity design has since been adapted as baseline for the main linac cavities in the proposed Powerful Energy Recovery Linac Experiment facility (PERLE) at Orsay. Details concerning the cavity fabrication and test results for the Nb cavities are presented.
 
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THPAL148 Status of High Efficiency Klystron Development in TETD klystron, cavity, simulation, bunching 3993
 
  • Y. Okubo, S. Fujii, K. Suzuki, T.E. Tanaka
    Toshiba Electron Tubes & Devices Co., Ltd (TETD), Tochigi, Japan
 
  TETD (Toshiba Electron Tubes and Devices Co., Ltd.) has been developing a high efficiency klystron improved bunch quality by the multi-stage of core oscillation design. For feasibility study, an S-band 7.5 MW klystron has been designed with the efficiency of more than 60% at 1.8μperveance. The first prototype was fabricated by modifying the interaction section of a commercial model to enhance the efficiency from 45% to 60%. The klystron was tested in June 2017, and 57% of efficiency at 6 MW output power was demonstrated. We are developing the second prototype which has the improved design for the higher efficiency at 7.5 WM output power. The design details and the test results of the first prototypes are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL148  
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THPMF012 Tapered Flying Radiofrequency Undulator undulator, FEL, simulation, ECR 4059
 
  • S.P. Antipov, S.V. Kuzikov, A. Liu
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • S.V. Kuzikov, A.V. Savilov, A.A. Vikharev
    IAP/RAS, Nizhny Novgorod, Russia
 
  Funding: DOE SBIR DE-SC0017145
The x-ray free electron laser (x-FEL) efficiency, measured as a fraction of the electron beam power converted into light, is typically below 0.1% for most of the x-FEL facilities presently in operation. Undulator tapering techniques can be used to improve the conversion efficiency by 1-2 orders of magnitude. However at present there are no robust tapered undulator x-FEL schemes operating at 10% efficiency. In this paper we report on the development of tapered radiofrequency (RF) undulator. An RF undulator is a microwave waveguide in which strong RF field is excited that interacts with a charged particle beam forcing it to radiate coherent x-rays while undergoing a wiggling motion. RF undulators are attractive for use in x-FELs due to their large beam aperture and a short undulator period. Strongly tapered RF undulators (with tapering of a wavelength) due to non-resonant trapping regime allow keeping high overall XFEL efficiency being driven by laser plasma accelerated beams usually having high enough current but large energy spread (1-10%).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF012  
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THPMF014 First Experiments at the CLEAR User Facility experiment, radiation, operation, plasma 4066
 
  • R. Corsini, A. Curcio, S. Curt, S. Döbert, W. Farabolini, D. Gamba, R. Garcia Alia, T. Lefèvre, G. McMonagle, P.K. Skowroński, M. Tali, F. Tecker
    CERN, Geneva, Switzerland
  • E. Adli, C.A. Lindstrøm, K.N. Sjobak
    University of Oslo, Oslo, Norway
  • R.M. Jones, A. Lagzda
    UMAN, Manchester, United Kingdom
 
  The new "CERN Linear Electron Accelerator for Research" (CLEAR) facility at CERN started its operation in fall 2017. CLEAR results from the conversion of the CALIFES beam line of the former CLIC Test Facility (CTF3) into a new testbed for general accelerator R&D and component studies for existing and possible future accelerator applications. CLEAR can provide a stable and reliable electron beam from 60 to 220 MeV in single or multi bunch configuration at 1.5 GHz. The experimental program includes studies for high gradient acceleration methods, e.g. for CLIC X-band and plasma technology, prototyping and validation of accelerator components, e.g. for the HL-LHC upgrade, and irradiation test capabilities for characterization of electronic components and for medical applications. An overview of the facility capabilities and a summary of the latest results will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF014  
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THPMF015 Lifetime and Beam Losses Studies of Partially Strip Ions in the SPS (129Xe39+) vacuum, injection, factory, beam-losses 4070
 
  • S. Hirlaender, R. Alemany-Fernández, H. Bartosik, N. Biancacci, T. Bohl, S. Cettour Cave, K. Cornelis, B. Goddard, V. Kain, M.W. Krasny, M. Lamont, D. Manglunki, G. Papotti, M. Schaumann, F. Zimmermann
    CERN, Geneva, Switzerland
  • K. Kroeger
    FSU Jena, Jena, Germany
  • V.P. Shevelko
    LPI RAS, Moscow, Russia
  • T. Stöhlker, G. Weber
    IOQ, Jena, Germany
 
  The CERN multipurpose Gamma Factory proposal relies on using Partially Stripped Ion (PSI) beams, instead of electron beams, as the drivers of its light source. If such beams could be successfully stored in the LHC ring, fluxes of the order of 1017 photons/s, in the gamma-ray energy domain between 1 MeV and 400 MeV could be achieved. This energy domain is out of reach for the FEL-based light sources as long as the multi TeV electron beams are not available. The CERN Gamma Factory proposal has the potential of increasing by 7 orders of magnitude the intensity limits of the present Inverse Compton Scattering sources. In 2017 the CERN accelerator complex demonstrated its flexibility by producing a new, xenon, ion beam. The Gamma Factory study group, based on this achievement, requested special studies. Its aim was to inject and to accelerate, in the SPS, partially stripped xenon ions Xe39+ measure their life time, and determine the relative strength of the processes responsible for the PSI beam losses. This study, the results of which are presented in this contribution, was an initial step in view of the the future studies programmed for 2018 with lead PSI beams.  
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THPMF016 Design of a Terahertz Radiation Source for Pump-Probe Experiments bunching, undulator, radiation, FEL 4073
 
  • J. Pfingstner, E. Adli
    University of Oslo, Oslo, Norway
  • E. Marín
    CERN, Geneva, Switzerland
  • S. Reiche
    PSI, Villigen PSI, Switzerland
 
  Narrow-band, tuneable, high-power terahertz radiation is highly demanded for pump-probe experiments at light source facilities. Since the requested radiation properties are not well covered by current terahertz radiation sources, an accelerator-based terahertz source employing the slotted-foil technique in combination with transverse deflecting cavities is proposed in this work. A detailed design has been worked out, and the behaviour of the electron beam and the created terahertz radiation is studied via numerical simulations. The results show that the proposed source produces tuneable terahertz radiation that can meet most of the demanded specifications.  
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THPMF024 Commissioning and Operation of FAST Electron Linac at Fermilab cavity, cryomodule, experiment, MMI 4096
 
  • A.L. Romanov, C.M. Baffes, D.R. Broemmelsiek, K. Carlson, D.J. Crawford, N. Eddy, D.R. Edstrom, E.R. Harms, J. Hurd, M.J. Kucera, J.R. Leibfritz, I.L. Rakhno, J. Reid, J. Ruan, J.K. Santucci, V.D. Shiltsev, G. Stancari, R.M. Thurman-Keup, A. Valishev, A. Warner
    Fermilab, Batavia, Illinois, USA
 
  We report results of the beam commissioning and first operation of the 1.3 GHz superconducting RF electron linear accelerator at Fermilab Accelerator Science and Technology (FAST) facility. Construction of the linac was completed and the machine was commissioned with beam in 2017. The maximum total beam energy of about 300 MeV was achieved with the record energy gain of 250 MeV in the ILC-type SRF cryomodule. The pho-toinjector was tuned to produce trains of 200 pC bunches with a frequency of 3 MHz at a repetition rate of 1 Hz. This report describes the aspects of machine commission-ing such as tuning of the SRF cryomodule and beam optics optimization. We also present highlights of an experimental program carried out parasitically during the two-month run, including studies of wake-fields, and advanced beam phase space manipulation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF024  
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THPMF025 Emittance Measurements at FAST Facility emittance, MMI, linac, controls 4100
 
  • J. Ruan, D.R. Broemmelsiek, D.J. Crawford, A.L. Edelen, J.P. Edelen, D.R. Edstrom, A.H. Lumpkin, P. Piot, A.L. Romanov, R.M. Thurman-Keup
    Fermilab, Batavia, Illinois, USA
  • P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
 
  Funding: *Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
The FAST facility at Fermilab recently been commissioned has demonstrated the generation of electron beam within a wide range of parameter (energy, charge) suitable for accelerator-science and beam-physics experiments. This accelerator consists of a photo-electron gun, injector, ILC-type cryomodules, and multiple downstream beam-lines. It will mainly serve as injector for the upcoming Integrable Optical Test Accelerator (IOTA). At the same time we will also carry out a LINAC based intense gamma ray experiment based on the Inverse Compton scattering. It is essential to understand the beam emittance for both experiments. A number of techniques are used to characaterizing the beam emittance including slit based method and quad scan method. An on-line emittance measurement based on multi-slit method is developed so the emittance measured will be immediately available to support further beam optimization. In this report we will present the results from the emittance studies using this tool. We will also present the emittance measurement based on quads scan technique for the high energy beam line.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF025  
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THPMF029 Novel MCP-Based Electron Source Studies laser, gun, cathode, controls 4107
 
  • V.D. Shiltsev, G. Stancari
    Fermilab, Batavia, Illinois, USA
  • M.J. Haughey
    Edinburgh University, Edinburgh, United Kingdom
 
  Microchannel plates were recently proposed as cathodes for electron guns, as part of a novel electron lens design to be tested in the IOTA facility at FNAL. We experimentally assessed the suitability of microchannel plate technology in this design and studied the microchannel plate based photomultiplier (MCP-PMT) system using different sources of light pulses. Here we present the results of the nanosecond time response tests and the maximum current density tests as well as the dependency on the magnetic field strength. Several ideas how to proceed beyond O(100 mA/cm2) density observed in the first tests.  
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THPMF038 Status of the BESSY VSR Project cavity, vacuum, operation, SRF 4138
 
  • P. Schnizer, W. Anders, Y. Bergmann, P. Goslawski, H. Hartmut, A. Jankowiak, J. Knobloch, A. Neumann, K. Ott, M. Ries, A. Schälicke, A.V. Vélez
    HZB, Berlin, Germany
 
  BESSY VSR is set out to provide a variable pulse pattern to the BESSY II users. This project is now fully funded and heading into its implementation phase. The pulse pattern, consisting of long and short pulses, require inserting cavities providing a 3rd and a 3.5th harmonic of the fundamental harmonic of the ring. Therefore 1.5 and 1.75 GHz cavities are developed with appropriate higher order mode damping spectrum. Similarly the BESSY II ring and injector chain has to be upgraded to provide appropriate diagnostics and increase the injection efficiency. In this paper we give the current status of the project and give an overview of scientific challenges currently being tackled.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF038  
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THPMF040 Experiences with the SRF Gun II for User Operation at the ELBE Radiation Source gun, radiation, SRF, undulator 4145
 
  • J. Teichert, A. Arnold, M. Bawatna, P.E. Evtushenko, M. Gensch, B.W. Green, S. Kovalev, U. Lehnert, P.N. Lu, P. Michel, P. Murcek, H. Vennekate, R. Xiang
    HZDR, Dresden, Germany
 
  Funding: The work is supported by the German Federal Ministry of Education and Research (BMBF) grant 05K12CR1.
The second version of the superconducting RF pho-toinjector (SRF Gun II) was successfully commissioned at the ELBE radiation source in 2014. The gun features an improved 3.5-cell niobium cavity combined with a super-conducting solenoid integrated in the cryostat. With a Mg photocathode the SRF Gun II is able to generate bunches with up to 200 pC and with sub-ps length in CW mode with 100 kHz pulse frequency for the THz radiation fa-cility at ELBE. In the ELBE linac, the beam is accelerat-ed, gets a proper correlated energy spread, and is com-pressed in a magnetic chicane. Sub-ps pulses are obtained producing coherent diffraction radiation and superradiant undulator radiation.
 
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THPMF045 Synchronized Beam Position Measurement for SuperKEKB Injector Linac linac, controls, EPICS, operation 4159
 
  • M. Satoh, F. Miyahara, T. Suwada
    KEK, Ibaraki, Japan
  • T. Kudou, S. Kusano
    Mitsubishi Electric System & Service Co., Ltd, Tsukuba, Japan
  • T. Ohfusa, H.S. Saotome, M. Takagi
    Kanto Information Service (KIS), Accelerator Group, Ibaraki, Japan
 
  Toward SuperKEKB project, the injector linac upgrade is ongoing for aiming at the stable beam operation with low emittance and high intensity bunch charge. One of the key challenges is a low emittance preservation of electron beam because the vertical emittance of 20 mm.mrad or less should be transported to the main ring without a damping ring. For this purpose, the fine alignment of accelerator components is a crucial issue since the linac alignment was badly damaged by the big earthquake in 2011. From the simulation results of emittance growth, the alignment of the quadrupole magnets and accelerating structures should be conducted at the level of 300 um in rms along the 600-m-long linac. In addition, we are aiming at the level of 100 um alignment in rms within the short range distance of 100 m long. Even after the fine component alignment can be achieved, the fine beam orbit manipulation is necessary for low emittance preservation. For these reasons, we have developed the new BPM readout system based on VME64x. The new system has improved the precision of beam position measurement up to 3 um from 25 um. We will describe the software development of the new BPM readout system.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF045  
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THPMF046 Precision Charge Measurement of 40~MeV Electron-Beam to Calibrate Air Fluorescence Telescope for Cosmic Ray Observation vacuum, ECR, injection, ISOL 4163
 
  • T. Shibata
    KEK, Ibaraki, Japan
  • O.C. Shin
    OCU, Osaka, Japan
 
  The Telescope Array (TA) is ultra-high energy cosmic ray observation (UHECR). TA is using the fluorescence detectors (FD) for observation the air fluorescence(AFY) which are emitted in the cascade generated by an UHECR in atmosphere. One of the important observables is primary energy of UHECR, however it has 21% systematic uncertainty. For reduction of the uncertainty, we have been operated an 40-MeV electron linear accelerator from 2010 which we have constructed for absolute energy calibration. The accelerator is located at 100 m from FD station, and can shot electron beam which the direction is vertical into the air, the energy is 40-MeV, the pulse width is 1 micro-second, and the beam charge is 160 pC. The AFY efficiency and FD calibration parameters can be calibrated, which means energy scale of UHECR, by observation of the AFY which are generated by the electron beam in the air. The most important beam parameter is beam charge. The requirement of the accuracy of charge measurement is a few %, then we have developed the double faraday cups and one current transfer system. We calibrated the current transfer by the double faraday cups, and we could achieve about 1% accuracy.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF046  
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THPMF048 Bunch Length Measurements Using CTR at the AWA with Comparison to Simulation experiment, simulation, laser, gun 4166
 
  • N.R. Neveu
    IIT, Chicago, Illinois, USA
  • S.P. Antipov
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • A. Halavanau, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • P. Piot
    Fermilab, Batavia, Illinois, USA
  • J.G. Power, C. Whiteford, E.E. Wisniewski
    ANL, Argonne, Illinois, USA
  • L.K. Spentzouris
    Illinois Institute of Technology, Chicago, Illinois, USA
 
  Funding: This work is funded by the DOE Office of Science, grant no. DE-SC0015479, and contract No. DE-AC02- 06CH11357.
In this paper we present electron bunch length measurements at the Argonne Wakefield Accelerator (AWA) photoinjector facility. The AWA accelerator has a large dynamic charge density range, with electron beam charge varying between 0.1 nC - 100 nC, and laser spot size diameter at the cathode between 0.1 mm - 18 mm. The bunch length measurements were taken at different charge densities using a metallic screen and a Martin-Puplett interferometer to perform autocorrelation scans of the corresponding coherent transition radiation (CTR). A liquid helium-cooled 4K bolometer was used to register the interferometer signal. The experimental results are compared with Impact-T and OPAL-T numerical simulations.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF048  
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THPMF050 High-Efficient XFELO Based on Optical Resonator with Self-Modulated Q-Factor undulator, FEL, laser, coupling 4172
 
  • S.V. Kuzikov, A.V. Savilov, A.A. Vikharev
    IAP/RAS, Nizhny Novgorod, Russia
  • S.P. Antipov, S.V. Kuzikov
    Euclid TechLabs, LLC, Solon, Ohio, USA
 
  In this paper we describe an efficient XFELO having a new non-stationary out-coupling scheme. It consists of two undulator sections placed inside optical cavity. The first section is a conventional uniform undulator and the second one is a tapered undulator. At start time point X-ray radiation is mostly produced by the uniform section. Mirrors of XFELO's optical resonator are designed so that diffraction Q-factor reaches the highest value, i.e losses are near zero. As X-ray power increases the tapered undulator begins to contribute more to radiation power. However a portion of that power misses mirrors of the optical cavity, because those are tuned to confine radiation produced by the first undulator. This process establishes a steady state operation of the XFELO.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF050  
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