THPML —  MC3/6/7 Poster Session   (03-May-18   16:00—17:30)
Paper Title Page
THPML002 Emittance Preservation in Plasma-Based Accelerators with Ion Motion 4654
 
  • C. Benedetti, E. Esarey, W. Leemans, T.J. Mehrling, C.B. Schroeder
    LBNL, Berkeley, California, USA
 
  Funding: This work was supported by the Director, Office of Science, Office of High Energy Physics, of the U.S. DOE under Contract No. DE-AC02-05CH11231.
In a plasma-accelerator-based linear collider, the density of matched, low-emittance, high-energy particle bunches required for collider applications can be orders of magnitude above the background ion density, leading to ion motion, perturbation of the focusing fields, and, hence, to beam emittance growth. By analyzing the response of the background ions to an ultrahigh density beam, analytical expressions, valid for non-relativistic ion motion, are obtained for the perturbed focusing wakefield. Initial beam distributions are derived that are equilibrium solutions, which require head-to-tail bunch shaping, enabling emittance preservation with ion motion.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML002  
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THPML006 Using Drive Rods in Inductions Cells to Reduce the Beam Break Up Instability 4658
 
  • N. Pogue, T.L. Houck, B.R. Poole
    LLNL, Livermore, California, USA
 
  The Beam Breakup Instability is a critical effect to reduce in high current induction accelerators. The RF modes generated inside the induction cells can deflect or degrade subsequent beam traversing the cell. Significant effort has been invested in minimizing the effect over several decades. One mechanism that is known to reduce the transverse impedance, the main observable experimentally which directly relates to the BBU amplitude, is to introduce ferrites to absorb the fields. Another, less investigated mechanism, is to disturb the modes symmetry by inserting the drive rods at the proper locations in the cell. This paper will show that the drive rods can dramatically reduce the transverse impedance, and will show that simulations are maturing towards predicting this effect. Lawrence Livermore National Laboratory is operated by Lawrence Livermore National Security, LLC, for the U.S. Department of Energy, National Nuclear Security Administration under Contract DE-AC52-07NA27344.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML006  
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THPML007 An Investigation of Electron Beam Divergence from a Single DFEA Emitter Tip 4662
 
  • H.L. Andrews, B.K. Choi, R.L. Fleming, D. Kim, J.W. Lewellen, K.E. Nichols, D.Y. Shchegolkov, E.I. Simakov
    LANL, Los Alamos, New Mexico, USA
 
  Funding: We gratefully acknowledge the support of the U.S. Department of Energy through the LANL/LDRD Program for this work.
Diamond Field-Emitter Array (DFEA) cathodes are arrays of micron-scale diamond pyramids with nanometer-scale tips. DFEAs can produce high emission currents with small emittance and energy spread. At LANL, we have an ongoing program to test DFEA cathodes for the purpose of using them to generate high-current, low-emittance electron beams for dielectric laser accelerators. We have recently upgraded our cathode test chamber to use a mesh anode in place of a solid luminescent anode. In addition to allowing for downstream beam transport, this arrangement may eliminate earlier problems with reduced cathode performance due to ion back-bombardment. We are measuring divergence of the electron beam past the mesh in an effort to characterize the inherent beam divergence off the diamond tip and divergence contribution from the mesh. We will compare these observations with theoretical and modeled values.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML007  
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THPML009 Polarized Deuteron Negative Ion Source for Nuclear Physics Applications 4665
 
  • V.G. Dudnikov, M.A. Cummingspresenter, R.P. Johnson
    Muons, Inc, Illinois, USA
  • A.V. Sy
    JLab, Newport News, Virginia, USA
 
  The proposed U.S. Electron-Ion Collider (EIC) provides a unique tool to explore the next frontier in Quantum Chromodynamics, the dependence of hadron structure on the dynamics of gluons and sea quarks. Polarized beams are essential to these studies; understanding of the hadron structure cannot be achieved without knowledge of the spin. The existing EIC concepts utilize both polarized electrons and polarized protons/light ion species to probe the sea quark and gluon distributions. Polarized deuterons provide an especially unique system for study by essentially providing a combination of quark and nuclear physics. We note that there are currently no operational polarized deuteron beam sources in the United States. This polarized deuteron source can serve as a polarized deuteron injector for a future EIC, with additional applications in polarimetry and polarized gas targets for experiments at CEBAF or RHIC and would be very useful for our future facilities.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML009  
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THPML010 Modeling of Diamond Field Emitter Arrays for Shaped Electron Beam Production 4668
 
  • K.E. Nichols, H.L. Andrews, D.Y. Shchegolkov, E.I. Simakov
    LANL, Los Alamos, New Mexico, USA
 
  We present simulations of shaped electron beam production from diamond field emitter array (DFEA) cathodes. DFEAs are arrays of diamond pyramids with bases of the order of 10 microns that produce high current densities. These arrays can be fabricated in arbitrary shapes such as a triangle or a double triangle, so that they produce an inherently shaped beam. These transversely shaped beams can be put through an emittance exchanger to produce a longitudinally shaped electron beam distribution for use with high-transformer ratio wakefield accelerators. Simulations are conducted with MICHELLE. We design cathodes and focusing systems that preserve the beam's shape while transporting it to the emittance exchanger.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML010  
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THPML011 Possibilities for Fabricating Polymer Dielectric Laser Accelerator Structures with Additive Manufacturing 4671
 
  • E.I. Simakov, R.D. Gilbertson, M.J. Herman, G. Pilania, D.Y. Shchegolkov, E.M. Walker, E. Weis
    LANL, Los Alamos, New Mexico, USA
  • R.J. England, K.P. Wootton
    SLAC, Menlo Park, California, USA
 
  Funding: Los Alamos National Laboratory LDRD Program
We present results of recent studies of new materials designed for the additive manufacturing of accelerating structures for dielectric laser accelerators (DLAs). Demonstration of a stand-alone practical DLA requires innovation in design and fabrication of efficient laser accelerator structures and couplers. Many complicated three-dimensional structures for laser acceleration (such as a long woodpile structure with couplers) are difficult to manufacture with conventional microfabrication technologies. LANL has a large effort focused on developing new materials and techniques for additive manufacturing. The materials for DLA structures must have high dielectric constant (larger than 4), low loss in the infrared regime, high laser damage threshold, and be able to withstand the electron beam damage. This presentation will discuss the development of novel infrared dielectric materials that are of interest for laser acceleration and are compatible with additive manufacturing, as well as recent advances in additive manufacturing of dielectric woodpile structures using a Nanoscribe direct laser-writing 3D printer.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML011  
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THPML012 Simulations and Measurements of the Wakefield Loading Effect in Argonne Wakefield Accelerator Beamline 4675
 
  • J. Upadhyay, E.I. Simakov
    LANL, Los Alamos, New Mexico, USA
  • M.E. Conde, Q. Gao, N.R. Neveu, J.G. Power, J.H. Shao, E.E. Wisniewski
    ANL, Argonne, Illinois, USA
  • N.R. Neveu
    IIT, Chicago, Illinois, USA
 
  A beam driven acceleration experiment in a photonic band gap (PBG) structure is planned at Argonne wakefied accelerator (AWA) facility at Argonne National Laboratory. We plan to pass a high charge (drive) beam through a travelling wave 11.7 GHz PBG structure and generate a wakefield. This wakefield will be probed by a low charge (witness) beam to demonstrate wakefield acceleration and deceleration. The drive and witness bunches will be accelerated to above 60 MeV in the main accelerator at AWA which has frequency of 1.3 GHz. The charges used in this experiment could be as high as 20 nC. To measure the exclusive effect of PBG the structure on acceleration and deceleration of the witness bunch we have to exclude the effect of beam loading of the main AWA accelerator structure. To understand the wakefield effect in AWA, we conducted an experiment where we passed the high charge (10 nC) beam through the accelerator structure which was followed by a 2 nC witness beam separated by 4 wavelength. The energy of witness beam was measured in the presence and absence of the drive beam. The beam loading was observed and quantified. The results of this work will be presented in the conference.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML012  
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THPML013 Demonstration of the Wakefield Acceleration in an 11.7 GHz Photonic Band Gap Accelerator Structure 4678
 
  • J. Upadhyay, E.I. Simakov
    LANL, Los Alamos, New Mexico, USA
  • M.E. Conde, Q. Gao, N.R. Neveu, J.G. Power, J.H. Shao, E.E. Wisniewski
    ANL, Argonne, Illinois, USA
 
  We plan to conduct a beam driven acceleration experiment in a photonic band gap (PBG) accelerator structure operating at 11.7 GHz at Argonne Wakefield Accelerator (AWA) facility. For the experiment, the PBG structure will be excited by a high charge (up to 10 nC) electron bunch, and a second smaller charge witness bunch will be accelerated. Because the PBG structure was fabricated with electroforming, the AWA beamline includes a Be window placed before the PBG structure that protects the cathode from contamination due to possible outgassing from the electroformed copper. The diameter of the Be window is 9 mm and the beam tube diameter of the PBG structure is 6.4 mm. The size of the high charge electron beam on Be window has to be minimized to minimize scattering. The parameters of the beamline had to be adjusted to achieve good propagation of the beam. An OPAL simulation for the AWA beamline was performed for 1, 5, and 10 nC beams. The beam size was experimentally measured at different positions in the beamline for different charges to verify simulations. Finally, the high charge electron beam was passed through the PBG structure and acceleration of the witness bunch was measured  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML013  
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THPML014 A Metamaterial Wagon Wheel Structure for Wakefield Acceleration by Reversed Cherenkov Radiation 4681
SUSPF036   use link to see paper's listing under its alternate paper code  
 
  • X.Y. Lu, I. Mastovsky, M.A. Shapiro, R.J. Temkin
    MIT/PSFC, Cambridge, Massachusetts, USA
  • M.E. Conde, C.-J. Jing, J.G. Power, J.H. Shao, E.E. Wisniewski
    ANL, Argonne, Illinois, USA
 
  Funding: U.S. Department of Energy, Office of Science, Office of High Energy Physics under Award Number DE-SC0015566 and the U.S. Department of Energy Office of Science under Contract No. DE-AC02-06CH11357
We present the design and experimental operation on an X-band metamaterial (MTM) wagon wheel structure for wakefield acceleration. The structure was designed and fabricated at MIT, and tested at the Argonne Wakefield Accelerator (AWA) laboratory at Argonne National Lab. The MTM wagon wheel structure is an all-metal periodic structure at 11.4 GHz. The fundamental TM mode has a negative group velocity, so when an electron beam travels through, energy is extracted from the beam by reversed Cherenkov radiation, which was verified in the experiment. Single bunches up to 45 nC were sent through the structure with a beam aperture of 6 mm and generated microwave power up to 25 MW in a 2 ns pulse, in agreement with both the analytical wakefield theory and the numerical CST simulations. Two bunches with a total charge of 85 nC generated 80 MW of microwave power. The structure is scalable to a power extractor of over 1 GW by increasing the structure length from 8 cm to 22 cm.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML014  
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THPML015 Dielectric Multipactor Discharges at 110 GHz 4684
 
  • S. C. Schaub
    MIT, Cambridge, Massachusetts, USA
  • M.A. Shapiro, R.J. Temkin
    MIT/PSFC, Cambridge, Massachusetts, USA
 
  A 1.5 MW, 110 GHz gyrotron has been used to experimentally measure the maximum sustainable fields on dielectric materials in vacuum. The purpose of this work is to evaluate the suitability of these materials for future applications in high frequency linear accelerators and high power terahertz components. To our knowledge, these are the first measurements of multipactor phenomena in the millimeter wave or terahertz frequency range. Materials tested include alumina, sapphire, fused quartz, crystal quartz, and high resistivity silicon. Dielectric samples were tested both as windows, with electric fields parallel to the surface, and sub-wavelength dielectric rod waveguides, with electric fields perpendicular to the surface. Surface electric fields in excess of 52 MV/m were achieved in 3 microsecond pulses. Visible light emission, absorbed/scattered microwave power, and emitted electrons were measured to characterize the discharges on the dielectric surfaces. The results of these experiments have been compared to theoretical calculations of multipactor discharges, testing these theories at significantly higher frequencies than has been done before.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML015  
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THPML017 Beam Dynamics Calculation of a New Injection System for LINAC II 4687
 
  • J.X. Zhang, M. Hüning
    DESY, Hamburg, Germany
 
  The Linac II at DESY (Deutsches Elektronen Synchrotron) is an electron/positron linear accelerator with a 400 MeV primary electron linac, an 800 MW positron converter, and a 450 MeV secondary electron/positron linac. For reliability two injection systems can be switched, a 150 kV bombarder diode gun dating from 1969 and a 100 kV triode gun commissioned in 2014. The older bombarder gun shall be replaced with a triode gun optimized for injection into the synchrotron radiation facility PETRA III. In this paper, the parameters of the existing injectors and the design considerations for the new injector are presented. The preliminary beam dynamics calculation of the new injection system will be performed; the future plan of the replacement will be discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML017  
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THPML018 Modeling of Self-Modulated Laser Wakefield Acceleration Driven by Sub-Terawatt Laser Pulses 4690
SUSPF035   use link to see paper's listing under its alternate paper code  
 
  • C.-Y. Hsieh, S.-H. Chen
    NCU, Chung Li, Taiwan
  • M.W. Lin
    National Tsing-Hua University (NTHU), Hsinchu, Taiwan
 
  Funding: This work has been supported by the Ministry of Science and Technology in Taiwan by grant MOST104-2112-M-008-013-MY3 and by grant MOST105-2112-M-007-036-MY3.
Laser wakefield accelerator (LWFA) can be achieved in a scheme in which a sub-terawatt (TW) laser pulse is introduced into a thin, high-density target*. As a result, the self-focusing and the self-modulation can greatly enhance the peak intensity of the laser pulse capable of exciting a nonlinear plasma wave to accelerate electrons. A particle-in-cell model was developed to study the sub-TW LWFA, in which a 0.6-TW laser pulse is injected into a hydrogen gas cell with a flat-top density profile. In addition to using 800-nm laser pulses, laser pulses of 1030 nm were used in simulations as they represent a viable approach to realize the sub-TW LWFA driven by high-frequency, diode-pumped laser systems**. Process of the electron injection is complicated in such a high-density plasma; however, the simulation results show that the appropriate injection and acceleration of electrons can be achieved by optimizing the length of the gas cell. When a 340-micrometer long gas cell is introduced, energetic electrons (> 1 MeV) are produced with a relatively low emittance of 3.5 pi-mm-mrad and a total charge of 0.32 nC accordingly.
* A. J. Goers et al., Phys. Rev. Lett. 115, 194802 (2015).
** E. Kaksis et al., Opt. Express 24, 25, 28915 (2016).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML018  
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THPML020 The First Results of Trial Operation and Performance Improve of the 100 MeV/ 100 kW Electron Linear Accelerator of the NSC KIPT SCA Neutron Source 4693
 
  • A.Y. Zelinsky, O.E. Andreev, V.P. Androsov, O. Bezditko, O.V. Bykhun, A.N. Gordienko, V.A. Grevtsev, A. Gvozd, V.E. Ivashchenko, I.I. Karnaukhov, I.M. Karnaukhov, V.P. Lyashchenko, M. Moisieienko, A.V. Reuzayev, D.V. Tarasov, V.I. Trotsenko
    NSC/KIPT, Kharkov, Ukraine
  • Y.L. Chi
    IHEP, Beijing, People's Republic of China
 
  The NSC KIPT SCA Neutron Source uses 100 MeV/ 100 kW electron linear accelerator as a driver for the generation of the initial neutrons. The trial operation of the accelerator was started in 2018. To provide design electron beam parameters is the primary task of the first stage of the trial operation. During the first stage of the accelerator operation the following tasks were under consideration: minimization of the electron beam losses along accelerator, providing of the stable electron beam pulse current, adjustment of the electron beam position along accelerator and providing of the uniform electron beam distribution at the tungsten neutron generating target. The main results of the accelerator operation and methods of performance improve are described in the paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML020  
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THPML021 Individual Acceptance Testing and Comprehensive Testing of NSC KIPT SCA Neutron Source Technological Systems and Equipment 4696
 
  • A.Y. Zelinsky, O.V. Bykhun, I.M. Karnaukhov, A. Mytsykov, I. Ushakov
    NSC/KIPT, Kharkov, Ukraine
  • I. Bolshinsky
    INL, Idaho Falls, Idaho, USA
  • Y. Gohar
    ANL, Argonne, Illinois, USA
 
  During 2016-2017 the installation, assembling and commissioning of the NSC KIPT SCA Neutron Source technological systems were completed. The facility was designed and developed by NSC KIPT of Ukraine in collaboration with ANL of USA. The construction of the neutron source facility was started in 2012. The neutrons of the subcritical assembly are generated by 100 MeV/ 100 kW electron beam uniformly distributed at the surface of the tungsten target. It is supposed that the facility will be used to perform basic and applied nuclear research, produce medical isotopes, and train nuclear specialists. The individual acceptance testing and comprehensive testing were conducted for the technological and engineering systems of the neutron source. The tests were performed in compliance with programs and methodologies agreed by the State Nuclear Regulatory Inspectorate of Ukraine. The testing results confirmed compliance of the equipment with technical specifications, standards, regulations and rules on nuclear and radiation safety and preparedness of these systems for trial operation with the KIPT neutron source. The trial operation of the NSC KIPT SCA 'Neutron Source' has been started.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML021  
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THPML022 Application of Surface Plasmon Polaritons on Charged particle Beam Diagnostics 4699
 
  • Z.G. Jiang, D. Gupresenter, Q. Gu, M.H. Zhao
    SINAP, Shanghai, People's Republic of China
 
  In Recent years, the Cherenkov light radiation transformed from surface plasmon polaritons has been found and proposed for a compact and adjustable light source. As the process is motivated by charged particle beam, the characteristics of the light are not only related with the device but can also reflect certain characteristics of the beam. In this paper, a beam position and energy measurement method has been proposed based on the Cherenkov light radiation transformed from surface plasmon polaritons. Early-stage numerical and analytical investigations are also presented for a planar structure device.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML022  
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THPML024 Monoenergetic Beam Generated by Laser Accelerator at Peking University 4702
 
  • K. Zhu, J.E. Chen, Y.X. Geng, C. Li, D.Y. Li, Q. Liao, C. Lin, H.Y. Lu, W.J. Ma, Y.R. Shou, Wu,M.J. Wu, X.H. Xu, X.Q. Yan, J.Q. Yu, Y.Y. Zhao, J.G. Zhu
    PKU, Beijing, People's Republic of China
 
  An ultrahigh-intensity laser incident on a target sets up a very strong electrostatic field exceeding 100 GV/m, it will few orders magnitude shrink down the traditional radio frequency accelerators. Whereas, to build a real accelerator for routine operation, many scientific and technical challenges for laser acceleration need to overcome before they could be applied to these applications. Recently A laser accelerator− Compact Laser Plasma Accelerator (CLAPA) is being built with a beam line to deliver proton beam with the energy of 1~15MeV, energy spread of ¡À1% and 107-8 protons per pulse. The very high current proton beam is accelerated in laser ultrathin-foil interaction and transported by a beam line consisting of the electric quadruple and analyzing magnets. It makes sure the good beam qualities such as energy spread, charge, repeatability and availability of different energy, which means that for the first laser acceleration becomes a real laser accelerator. With the development of high-rep rate PW laser technology, we can now envision a compact beam therapeutic machine of cancer treatment in the near future soon.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML024  
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THPML025 Operation of an RF Modulated Thermionic Electron Source at TRIUMF 4705
 
  • F. Ames, K. Fong, B. Humphries, S.R. Koscielniak, A. Laxdal, Y. Ma, T. Planche, S. Saminathan, E. Thoeng
    TRIUMF, Vancouver, Canada
 
  ARIEL (Advanced Rare IsotopE Laboratory) at TRIUMF will use a high-power electron beam to produce radioactive ion beams via photo-fission. The system has been designed to provide up to 10 mA of electrons at 30 MeV. The electron source delivers electron bunches with charge up to 16 pC at a repetition frequency of 650 MHz at 300 keV. The main components of the source are a gridded dispenser cathode (CPI - Y845) in an SF6 filled vessel and an in-air HV power supply. The beam is bunched by applying DC and RF fields to the grid. A macro pulse structure can be applied by additional low frequency modulation of the RF signal. This allows adjusting the average beam current by changing the duty factor of the macro pulsing. Unique features of the gun are its cathode/anode geometry to reduce field emission, and transmission of RF modulation via a dielectric (ceramic) waveguide through the SF6. The source has been installed and fully commissioned to a beam power up to 1 KW and tests with accelerated beams have been performed. Measurements of the beam properties and results from the commissioning and operational experiences of the source will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML025  
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THPML027 Longitudinal and Transverse Wakefields Simulations and Studies in Dielectric-Coated Circular Waveguides 4708
 
  • L. Ficcadenti
    Rome University La Sapienza, Roma, Italy
  • A. Biagioni
    INFN/LNF, Frascati (Roma), Italy
  • G. Castorina, D. Francescone, M. Marongiupresenter, M. Migliorati, A. Mostacci, L. Palumbo
    Sapienza University of Rome, Rome, Italy
 
  In recent years, there has been a growing interest and rapid experimental progress on the use of e.m. fields produced by electron beams passing through dielectric-lined structures and on the effects they might have on the drive and witness bunches. Short ultra-relativistic electron bunches can excite very intense wakefields, which provide an efficient acceleration through the dielectric wakefield accelerators (DWA) scheme with higher gradient than that in the conventional RF LINAC. These beams can also generate high power narrow band THz coherent Cherenkov radiation. These high gradient fields may create strong instabilities on the beam itself causing issues in plasma acceleration experiments (PWFA), plasma lensing experiments and in recent beam diagnostic applications. In this work we report the results of the simulations and studies of the wakefields generated by electron beams at different lengths and charges passing on and off axis in dielectric-coated circular waveguides. We also propose a semi-analytical method to calculate these high gradient fields without resorting to time consuming simulations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML027  
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THPML028 Genetic Algorithms for Machine Optimization in the Fair Control System Environment 4712
 
  • W. Geithner, Z. Andelkovic, S. Appel, O. Geithnerpresenter, F. Herfurth, S. Reimann, G. Vorobjev
    GSI, Darmstadt, Germany
  • F. Wilhelmstötter
    emarsys, Vienna, Austria
 
  Due to the massive parallel operation modes at the GSI accelerators, a lot of accelerator setup and re-adjustment have to be made by the operators during a beam time. With the FAIR project the complexity of the accelerator facility increases furthermore and for efficiency reasons it is recommended to establish a high level of automation for future operation. The PEP (parameter evolution project) has been launched at GSI operations group in 2017 to investigate the potential of a settings optimization using evolutionary Algorithms. The working proof of principle has already been tested at the Cryring injector. The latest improvements and the further Development of the Parameter Evolution Project will be shown.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML028  
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THPML031 Collective Acceleration of Laser Plasma in Non-stationary and Non-uniform Magnetic Field 4716
 
  • A.A. Isaev, C.I. Kozlovskij, E.D. Vovchenko
    MEPhI, Moscow, Russia
 
  This paper presents the new experimental results concerning acceleration of deuterium ions extracted from laser plasma in the rapid-growing nonuniform magnetic field in order to initiate the nuclear reactions D(d, n)3He and Т (d,n)4He. In order to obtain plasma a laser that generates in Q-switched mode the pulses of infrared radiation (λ = 1.06 μm) with the energy W ≤ 0.85 J and duration of ≈10 ns. In the present study, the velocity of a bunch of a laser plasma at a magnetic field induction rate of 3-108 T/s was experimentally measured, and angular distributions of accelerated particle fluxes were measured in the range from 0 to 30 degrees. The maximum and mean ion velocities were determined by the time-of-flight technique. The proposed system allows the generation of neutrons, including possibly thermonuclear ones, on counterflows using two similar magnetic accelerators located coaxially, facing each other. In this case the problem related to degradation of solid neutron-generating targets is resolved. There also occurs a possibility of fast accumulated running time of packed solid targets at using of deuteron-tritium laser targets.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML031  
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THPML032 Using Deep Reinforcement Learning for Designing Sub-Relativistic Electron Linac 4720
SUSPF038   use link to see paper's listing under its alternate paper code  
 
  • Shin, S.W. Shin, J.-S. Chai, M. Ghergherehchi
    SKKU, Suwon, Republic of Korea
 
  Generally, when designing an accelerator device, the design is based on the experience and knowledge of the designer. Most of the design process proceeds by chang-ing the parameters and looking at the trends and then determining the optimal values. This process is time-consuming and tedious. In order to efficiently perform this tedious design process, a method using an optimization algorithm is used. Recently, many people started to get interested in the algorithm used in AlphaGo, which became famous when it won the professional Go player developed by google The algorithm used in AlphaGo is an algorithm called reinforcement learning that learns how to get optimal reward in various states by moving around a solution space that the agent has not told beforehand. In this paper, we will discuss about designing an particle accelerator by applying Deep Q-network algorithm which is one kind of deep learning reinforcement learning.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML032  
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THPML033 Towards a Free Electron Laser Using Laser Plasma Acceleration 4723
 
  • A. Loulergue, T. André, I.A. Andriyash, C. Benabderrahmane, P. Berteaud, F. Blache, C. Bourassin-Bouchet, F. Bouvet, F. Briquez, L. Chapuis, M.-E. Couprie, D. Dennetière, Y. Dietrich, J.P. Duval, M. El Ajjouri, T.K. El Ajjouri, A. Ghaith, C. Herbeaux, N. Hubert, M. Khojoyan, C.A. Kitegi, M. Labat, N. Leclercq, A. Lestrade, O. Marcouillé, F. Marteau, P. N'gotta, D. Oumbarek, F. Polack, P. Rommeluère, M. Sebdaoui, K.T. Tavakoli, M. Valléau, J. Vétéran, C. de Oliveira
    SOLEIL, Gif-sur-Yvette, France
  • S. Bielawski, C. Evain, E. Roussel, C. Szwaj
    PhLAM/CERLA, Villeneuve d'Ascq, France
  • S. Corde, J. Gautier, J.-P. Goddet, G. Lambert, B. Mahieu, V. Malka, J.P. Rousseau, S. Sebban, K. Ta Phuoc, A. Tafzi, C. Thaury
    LOA, Palaiseau, France
  • O. S. Kononenko
    DESY, Hamburg, Germany
  • S. Smartzev
    Weizmann Institute of Science, Physics, Rehovot, Israel
 
  Since the laser invention, the advent of X-ray Free Electron Lasers (FEL) half a century later, opens new areas for matter investigation. In parallel, the spectacular development of laser plasma acceleration (LPA) with several GeV beam acceleration in an extremely short distance appears very promising. As a first step, the qualification of the LPA with a FEL application sets a first challenge. Still, energy spread and beam divergence do not meet the state-of-the-art performance of the conventional accelerators and have to be manipulated to fulfill the FEL requirement. We report here on the undulator spontaneous emission measured after a transport manipulation electron beam line, using variable permanent magnet quadrupoles of variable strength for emittance handing and a demixing chicane equipped with a slit for the energy spread. Strategies of control electron beam position and dispersion have been elaborated. The measured undulator radiation provides an insight on the electron beam properties.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML033  
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THPML034 Baseline Lattice for the Upgrade of SOLEIL 4726
 
  • A. Loulergue, P. Alexandre, P. Brunelle, O. Marcouillé, A. Nadji, L.S. Nadolski, R. Nagaoka, K.T. Tavakoli, M.-A. Tordeux, A. Vivoli
    SOLEIL, Gif-sur-Yvette, France
  • L. Hoummi
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
 
  Previous MBA studies converged to a lattice composed of 7BA-6BA with a natural emittance value of 200- 250 pm.rad range. Due to the difficulties of non-linear optimization in targeting lower emittance values, a decision was made to symmetrize totally the ring with 20 identical cells having long free straight sections longer than 4 m. A 7BA solution elaborated by adopting the sextupole paring scheme with dispersion bumps originally developed at the ESRF-EBS, including reverse-bends, enabling an emittance of 72 pm.rad has been defined as the baseline lattice. The sufficient on-momentum dynamic aperture obtained allows to consider off-axis injection. The linear and nonlinear dynamic properties of the lattice along with the expected performance in terms of brilliance and transverse coherence are presented. In particular, the beta functions tuned down to 1 m in both transverse planes at the center of straight sections allow matching diffraction limited photons up to 3 keV.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML034  
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THPML041 FEBIAD Ion Source Development at TRIUMF-ISAC 4730
 
  • B.E. Schultz, F. Ames, O.K. Kester, P. Kunz, A. Mjøs, J.F. Sandor
    TRIUMF, Vancouver, Canada
 
  The ISOL facility TRIUMF-ISAC utilizes a number of different ion sources to produce radioactive ion beams. Most isotopes are ionized using surface or resonant laser ionization, but these techniques are prohibitively inefficient for species with high ionization energies, such as noble gases and molecules. For these cases, the Forced Electron Beam Induced Arc Discharge (FEBIAD) ion source can be used. The FEBIAD uses a hot cathode to produce electrons, which are accelerated through a potential (< 200 V) into the anode volume. Isotopes entering the resulting plasma undergo impact ionization and are extracted. Efforts are under way to better understand the physics and operation of the FEBIAD, using both theory and experiment. Recent measurements and simulations on the ISAC FEBIAD will be reported here.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML041  
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THPML042 Integrating the Lorentz Force Law for Highly-Relativistic Particle-in-Cell Simulations 4734
 
  • A.V. Higuera, J.R. Cary
    Tech-X, Boulder, Colorado, USA
  • J.R. Cary
    CIPS, Boulder, Colorado, USA
 
  Funding: This work is supported by the DOE under Grants No. DE-SC0011617 and DE-SC0012444, and by DOE/NSF Grant No. DE-SC0012584
Integrating the Relativistic Lorentz Force Law for plasma simulations is an area of current research (*, **, ***). In particular, recent research indicates that interaction with highly-relativistic laser fields is particularly problematic for current integration techniques (****). Here is presented a special-purpose integrator yielding improved accuracy for highly-relativistic laser-particle interactions. This integrator has been implemented in the particle-in-cell code VSim, and the authors present an accuracy and performance comparison with several particle push methods.
* http://aip.scitation.org/doi/abs/10.1063/1.4979989
** https://arxiv.org/abs/1702.04486
*** https://arxiv.org/abs/1710.09164
**** http://aip.scitation.org/doi/abs/10.1063/1.4905523
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML042  
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THPML043 Optimization of Dielectric Laser-Driven Accelerators 4737
 
  • C.P. Welsch, M.G. Ibison, Y. Wei
    The University of Liverpool, Liverpool, United Kingdom
  • M.G. Ibison, Y. Wei, C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • J.D.A. Smith
    TXUK, Warrington, United Kingdom
  • G.X. Xia
    UMAN, Manchester, United Kingdom
 
  Funding: This project has received funding from the European Union's Seventh Framework Programme for research, technological development and demonstration under grant agreement no 289191.
Dielectric laser-driven accelerators (DLAs) utilizing large electric field from commercial laser system to accelerate particles with high gradients in the range of GV/m have the potential to realize a first particle accelerator ‘on a chip'. Dual-grating structures are one of the candidates for DLAs. They can be mass-produced using available nanofabrication techniques due to their simpler structural geometry compared to other types of DLAs. Apart from the results from optimization studies that indicate the best structures, this contribution also introduces two new schemes that can help further improve the accelerating efficiency in dual-grating structures. One is to introduce a Bragg reflector that can boost the accelerating field in the channel, the other applies pulse-front-tilt operation for a laser beam to help extend the interaction length.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML043  
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THPML044 Operation of a Cryogenic Current Comparator with Nanoampere Resolution for Continuous Beam Intensity Measurements in the Antiproton Decelerator at CERN 4741
 
  • M.F. Fernandes, D. Alves, T. Koettig, A. Lees, J. Tan
    CERN, Geneva, Switzerland
  • M.F. Fernandes, C.P. Welschpresenter
    The University of Liverpool, Liverpool, United Kingdom
  • M. Schwickert, T. Stöhlker
    GSI, Darmstadt, Germany
  • T. Stöhlker
    IOQ, Jena, Germany
  • C.P. Welschpresenter
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
 
  Funding: This project has received funding from the European Union's Seventh Framework Programme, under grant agreement number 289485.
Low-intensity charged particle beams are particularly challenging for non-perturbative beam diagnostics due to the small amplitude of induced electromagnetic fields. The Antiproton Decelerator (AD) and Extra Low ENergy Antiproton (ELENA) rings at CERN decelerate beams containing 107 antiprotons. An absolute intensity measurement of the circulating beam is essential to monitor the operational efficiency and to provide important calibration data for the antimatter experiments. This paper reviews the design of an operational Cryogenic Current Comparator (CCC) based on Superconducting QUantum Interference Device (SQUID) for current and intensity monitoring in the AD. Such a system has been operational throughout 2017, relying on a stand-alone cryogenic infrastructure based on a pulse-tube cryocooler. System performance is presented and correlated with different working environments, confirming a resolution in the nanoampere range.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML044  
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THPML047 Design and Measurement of the X-Band Pulse Compressor for TTX 4745
 
  • Y.L. Jiang, H.B. Chen, C. Cheng, W. Gai, J. Shi, P. Wang, Z.H. Wangpresenter, X.W. Wu, H. Zha
    TUB, Beijing, People's Republic of China
 
  A radio frequency (RF) pulse compressor had been designed for the X-band (11.424 GHz) high power test stands at the Accelerator Laboratory of Tsinghua University. It is the SLED-I type pulse compressor, which uses a high quality factor corrugated circular cavity to store the RF power. An RF polarizer couples two quadrature modes into the cavity so that the pulse compressor needs only one cavity. The cavity implements HE1-1-14 mode, with the Q0 of 115, 000 and the coupling factor (β) of 3.23. The design and the microwave measurement before brazing of this pulse compressor are presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML047  
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THPML051 Electron Acceleration by Plasma Wave in the Presence of a Transversely Propagated Laser with Magnetic Field 4749
 
  • M. Yadav, S. C. Sharma
    DELTECH, New Delhi, India
  • D.N. Gupta, M. Kaurpresenter
    University of Delhi, Delhi, India
 
  It has been revealed that a relativistic plasma wave, having an extremely large electric field, may be utilized for the acceleration of plasma particles. The large accelerating field gradient driven by a plasma wave is the basic motivation behind the acceleration mechanism. Such a plasma wave can be excited by a single laser in the form wakefield in laser-plasma interactions. In this paper, we study the enhancement of electron acceleration by plasma wave in presence of a laser* propagated perpendicular to the propagation of the wake wave. Electrons trapped in the plasma wave are effectively accelerated by the additional field of the laser combined with wakefield. The additional resonance provided by the laser field contributes to the large energy gain of electrons during acceleration. The resonant enhancement of electron acceleration has been validated by single particle simulations**. The dependence of energy gain on laser intensity, laser spot size, initial electron energy, and electron trajectories have been investigated.
* G. D. Tsakiris, C. Gahn, and V. K. Tripathi, Phys. Plasmas 7, 3017 (2000)
** Maninder Kaur, and D. N. Gupta, IEEE, 45, p 2841 - 2847, (2017)
 
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THPML052 Excitation of Plasma Wave by Lasers Beating in a Collisional and Mild-Relativistic Plasma 4752
SUSPF044   use link to see paper's listing under its alternate paper code  
 
  • M. Kaur, D.N. Gupta
    University of Delhi, Delhi, India
 
  Funding: Work supported by Department of Science and Technology (DST), Government of India.
Excitation of plasma wave by two lasers beating in a collisional dominated relativistic plasma is investigated. We study the energy exchange between a plasma wave and two co-propagating lasers in plasma including the effect of relativistic mass change and electron-ion collisions. Two lasers, having frequency difference equal to the plasma frequency, excite a plasma beat wave resonantly by the ponderomotive force, which obeys the energy and momentum conservation*. The relativistic effect and the electron-ion collision both contribute in energy exchange between the interacting waves in the beat-wave acceleration mechanism. Our study shows that the initial phase difference between interacting waves generates a phase mismatch between lasers and plasma wave, which alters the rate of amplitude variations of the interacting waves and, hence, affects the energy exchange between the interacting waves**. This study may be crucial to design a compact plasma accelerator in low-intensity regime***.
*T. Tajima, and J. Dawson, Phys. Rev.Lett. 43, 267(1979)
**D. N. Gupta, M. S. Hur, and H. Suk, J.Appl. Phys. 100, 103101 (2006)
***M. Kaur and D. N. Gupta, EuroPhysics letter 116, 35001 (2016).
 
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THPML053 Computational Screening for Low Emittance Photocathodes 4755
 
  • J.T. Paul, R.G. Hennig
    University of Florida, Gainesville, Florida, USA
  • I.V. Bazarov, A. Galdi
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • S.S. Karkare, H.A. Padmore
    LBNL, Berkeley, California, USA
 
  The majority of photocathode materials in use in accelerator applications have been discovered empirically through trial and error with little guidance from material science calculations. Alternatively, one can envision a process which is heavily guided by computational search using latest advances in density functional theory (DFT). In this work, the MaterialsProject database is searched for potential single crystal photocathodes that would be suitable for ultralow emittance beam production. The materials in the database are initially screened on the basis of experimental practicality. Following this, the expected emittance is calculated from the DFT computed band structures for the pre-screened materials using the conservation of energy and transverse momentum during photoemission. Based on such computational screening, we provide a list of potential low emittance photocathode materials which can be investigated experimentally as high brightness electron sources.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML053  
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THPML054 Design Studies of an S-Band Multipacting Electron Gun 4759
SUSPF051   use link to see paper's listing under its alternate paper code  
 
  • C. Henkel, W. Hillert, V. Miltchev
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • K. Flöttmann
    DESY, Hamburg, Germany
 
  A multipacting electron gun (MEG) is a micro-pulse electron source based on secondary electron emission in a resonant microwave cavity structure for the generation of low emittance electron bunches with high repetition rate. By theoretical simulations a suitable radio-frequency gun design at 3 GHz is established, simultaneously meeting the demands of bunch production and amplification process as well as including the effects of space charge and beam loading for the evolution of a stable beam. In this contribution we show detailed simulation studies of the impact of important design parameters like mechanical dimensions and choice of material on the average output current, which is in the order of several mA. For the experimental investigation a test setup is under construction, which may demonstrate the application of MEG's as a serious alternative or addition to commonly used electron sources like thermionic and photocathodes.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML054  
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THPML055 Scaled Studies on Radio Frequency Sources for Megawatt-Class Ionospheric Heaters 4763
 
  • B.L. Beaudoin, T.M. Antonsen, J.A. Karakkad, A.H. Narayan, G.S. Nusinovich, K.J. Ruisardpresenter
    UMD, College Park, Maryland, USA
  • R. Fischer
    Naval Research Laboratory (NRL), Washington, USA
  • S.H. Gold, A. Ting
    NRL, Washington,, USA
 
  Funding: Funding for this project and travel is provided by the Air Force Office of Scientific Research under grant FA95501410019.
The ionosphere plays a prominent role in the performance of critical civilian and military communication systems. The key instrument in Ionospheric Modification (IM) research is a powerful, ground-based, High Frequency (HF) source of electromagnetic waves known as a heater. With a mobile heater, investigators would be able to conduct IM research at different latitudes without building a costly permanent installation. A new highly efficient Megawatt class of Radio Frequency sources is required to reduce the overall power demands on a fully deployable system. Such a source has been described previously*. Results of a scaled experiment, using the electron beam produced by a gridded gun to drive an external lumped element circuit for high efficiency radio frequency generation is presented. The IOT gun produces an electron beam bunched at the driving frequency that is then collected by an external circuit for impedance matching to the load. Results showed that effects such as the internal resistance of the inductor and deflection of beam electrons by the induced RF voltages on the beam collector are important considerations to be included in the design of a practical device.
* B.L. Beaudoin, G.S. Nusinovich, G. Milikh, A. Ting, S. Gold, J.A. Karakkad, A.H. Narayan, D.B. Matthew, D.K. Papadopoulos, T.M. Antonsen Jr., Journal of Elec. Waves and Appl.,31,17,pp.1786, 2017.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML055  
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THPML058 Recent Results from MICE on Multiple Coulomb Scattering and Energy Loss 4766
 
  • P. Franchini
    University of Warwick, Coventry, United Kingdom
 
  Funding: STFC, DOE, NSF, INFN, and CHIPP
Multiple Coulomb scattering and energy loss are well known phenomena experienced by charged particles as they traverse a material. However, from recent measurements made by the MuScat collaboration, it is known that the available simulation codes (GEANT4, for example) overestimate the scattering of muons in low Z materials. This is of particular interest to the Muon Ionization Cooling Experiment* (MICE) collaboration which has the goal of measuring the reduction of the emittance of a muon beam induced by energy loss in low Z absorbers. MICE took data without magnetic field suitable for multiple scattering measurements in the autumn of 2015 with the absorber vessel filled with xenon and in the spring of 2016 using a lithium-hydride absorber. In the autumn of 2016 MICE took data with magnetic fields on and studied the energy loss of muons in a lithium-hydride absorber. These data are all compared with the Bethe-Bloch formula and with the predictions of various models, including the default GEANT4 model.
*Submitted by the MICE Speakers bureau, to be prepared and presented by a MICE member to be selected in due course
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML058  
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THPML059 Re-Commissioning the Front End Test Stand Negative Hydrogen Ion Source, Beam Transport and Interlocks 4769
 
  • S.R. Lawrie, R.E. Abel, M. Dudman, D.C. Faircloth, A.P. Letchford, J.H. Macgregor, M. Perkins, T. M. Sarmento, R.C. Searle, M. Whitehead, T. Wood
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
 
  The front end test stand (FETS) is a demonstrator for a future high intensity, high duty factor negative hydrogen (H') ion injector. With the radio-frequency quadrupole (RFQ) nearing installation, the ion source has been re-commissioned in preparation for long-term operation. The 3 MeV beam exceeds the radio-activation energy of common engineering materials, so radiation shielding has been erected. A new interlocking scheme has been signed-off which integrates the existing ion source high voltage area with the new shielding access points, to ensure that the machine can operate safely during beam production. The existing vacuum arrangement has been extended to in-clude the RFQ and medium energy beam transport (MEBT) line. A new programmable logic controller (PLC) has been built to operate the entire vacuum chain. The ion source high voltage equipment has been upgraded to minimise both spark rate and intensity. A collimating aperture and Faraday cup have been installed after the low energy beam transport (LEBT) section to ensure the beam is well aligned for injection into the RFQ. Re-commissioning the ion source has given a rugged shakedown of all these new systems before beam is required for the RFQ.
*scott.lawrie@stfc.ac.uk
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML059  
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THPML060 Virtual VELA-CLARA: The Development of a Virtual Accelerator 4773
 
  • T.J. Price, H.M. Castaneda Cortes, D.J. Dunning, J.K. Jonespresenter, B.D. Muratori, D.J. Scott, B.J.A. Shepherd, P.H. Williams
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • R.F. Clarke, G. Cox
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
 
  A Virtual Accelerator (VA) has been developed to mimic the accelerators Versatile Electron Linear Accelerator (VELA) and Compact Linear Accelerator for Research and Applications (CLARA). Its purpose is to test control room applications, run start-to-end simulations with multiple simulation codes, accurately reproduce measured beam properties, conduct 'virtual experiments'and gain insight into ‘hidden beam parameters'. This paper gives an overview into the current progress in constructing this VA, detailing the areas of: developing a 'Virtual EPICS' control system, using multiple simulation codes (both particle tracking and analytic), the development of a ‘Master Lattice' and the construction of a Python interface in which to run the VA.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML060  
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THPML061 X-Band Low Q Cavity Beam Position Monitor Study 4777
SUSPF093   use link to see paper's listing under its alternate paper code  
 
  • S.S. Cao
    SINAP, Shanghai, People's Republic of China
  • Y.B. Leng, R.X. Yuan
    SSRF, Shanghai, People's Republic of China
 
  The high repetition-rate and high peak brilliance of X-ray free-electron laser (XFEL) allow studying many scientific experiments that have not been feasible. To realize such high performance, a sub-micron beam transverse position measurement is required. The cavity-type beam position monitor (CBPM), as a non-destructive diagnostics tool with high potential in resolution performance, has been applied in different free electron laser facilities (FELs). In this research, an X-band high bandwidth CBPM has been studied and used for pre-research on bunch-by-bunch diagnostic for the pulsed FEL with high repetition-rate. Its bandwidth reaches 300 MHz. Design considerations and simulation results of the CBPM have been discussed and presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML061  
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THPML062 A Beam Based Method to Optimize the SBPM System 4780
SUSPF095   use link to see paper's listing under its alternate paper code  
 
  • J. Chen
    SINAP, Shanghai, People's Republic of China
  • L.W. Lai, Y.B. Leng, T. Wu, R.X. Yuan
    SSRF, Shanghai, People's Republic of China
 
  For the electron accelerator, it is hoped that the trajec-tory of the beam can pass through the magnetic center of the quadrupole to minimize the orbital motion caused by the instability of the power supply. The relative deviation between the magnetic center of quadrupole and the elec-tric center of adjacent BPM is measured by electron beam usually in various accelerator facilities. But for the stripline BPM (SBPM) system, in order to achieve the best performance, the beam trajectory should also need to pass through the electrical center of the SBPM system. In this paper, a beam based method to optimize the SBPM system was proposed, the intensity of the magnet power was scanned to change the beam position in two-dimension and combine the change trend of the sum signal of adjacent SBPM to find out the relative deviation of BPM electric center and mechanical center. Relevant beam experiment work on the Shanghai Soft X-ray free electron laser (SXFEL) and the benefit of this method will be addressed as well.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML062  
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THPML063 Micro-Bunched Beam Production at FAST for Narrow Band THz Generation Using a Slit-Mask 4784
 
  • J. Hyun
    Sokendai, Ibaraki, Japan
  • D.J. Crawford, D.R. Edstrom, J. Ruan, J.K. Santucci, T. Sen, J.C.T. Thangaraj, R.M. Thurman-Keup
    Fermilab, Batavia, Illinois, USA
 
  We discuss simulations and experiments on creating micro-bunch beams for generating narrow band THz radiation at the Fermilab Accelerator Science and Technology (FAST) facility. The low-energy electron beamline at FAST consists of a photoinjector-based RF gun, two L-band superconducting accelerating cavities, a chicane, and a beam dump. The electron bunches are lengthened with cavity phases set off-crest for better longitudinal separation and then micro-bunched with a slit-mask installed in the chicane. We carried out the experiments with 30 MeV electron beams and detected signals of the micro-bunching using a skew quadrupole magnet in the chicane. In this paper, the details of micro-bunch beam production, the detection of micro-bunching and comparison with simulations are described.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML063  
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THPML065 Preliminary Results of the Bunch Arrival-Time Monitor at SXFEL 4787
 
  • J.G. Wang, B. Liu
    SINAP, Shanghai, People's Republic of China
 
  Based on an electro-optical intensity modulation detection scheme, a Bunch Arrival-time Monitor (BAM) is under study at Shanghai soft X-ray Free Electron Laser (SXFEL) to meet the high-resolution requirements of the measurement of bunch arrival time. The first BAM is installed and is being tested at the SXFEL upstream of the first short undulator (modulator) near the seed laser injection point. In this paper, we present the basic working principle, the design of the BAM system and report the preliminary test results.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML065  
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THPML066 Filling Pattern Measurement System Upgrade in SSRF* 4791
 
  • N. Zhang, F.Z. Chenpresenter, Y.M. Zhou
    SSRF, Shanghai, People's Republic of China
 
  Funding: Work supported by National Natural Science Foundation of China (No.11575282 No.11375255 No.11305253)
Filling pattern affects various operation performance of a synchrotron light source. A new diagnostic beam charge monitor (BCM) with high bandwidth multi-channels digitizer was developed to perform bunch-by-bunch charge measurement and record filling pattern for SSRF storage ring. Signals picked up from button elec-trodes were sampled synchronously with RF frequency, and IQ (In-phase and Quadrature phase) sampling meth-od was employed for noise-filtering and phase independ-ence calibration. Layout and evaluation experiment of the system are presented in this paper.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML066  
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THPML067 SXFEL Linac BPM System Development and Performance Evaluation 4794
SUSPF094   use link to see paper's listing under its alternate paper code  
 
  • F.Z. Chen, T. Wu
    SSRF, Shanghai, People's Republic of China
  • J. Chen, L.W. Lai, Y.B. Leng, L.Y. Yu, R.X. Yuan
    SINAP, Shanghai, People's Republic of China
 
  Shanghai Soft X-ray Free Electron Laser (SXFEL) is a test facility to study key technologies and new FEL physics. In order to deliver high quality electron beams to the undulator section, a high resolution (better than 10 microns with 200pC beam) Linac beam position monitor system has been developed. The system consists of stripline pickup and custom designed DBPM processor. The hardware and software architecture will be introduced in this paper. The online performance evaluation results will be presented as well.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML067  
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THPML068 Upgrade of Bunch Phase Monitor at SSRF Storage Ring 4797
 
  • Y.M. Zhou, Y.B. Lengpresenter, T. Wu, N. Zhang
    SSRF, Shanghai, People's Republic of China
 
  Beam instability is a serious problem for physics in beam diagnosis technology. With regard to the evaluation of longitudinal phase oscillations during the transient injection process, bunch-by-bunch phase measurement is a useful tool for studying the behavior of the refilled bunches. A new upgraded beam phase monitor system with 1.2GHz bandwidth PXI waveform digitizer has been developed at Shanghai synchrotron radiation source (SSRF). Bunch-by-bunch phase information, retrieved from button pickup signals, is calculated by the zero-crossing detection method with the best phase resolution of 0.4ps. The refilled bunches can be separated from the stored ones, and the longitudinal offset of each refilled bunch has been measured. Several groups of experiments have been performed to verify the repeatability of bunch-by-bunch phase measurement, and some results regarding refilled bunches will be discussed in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML068  
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THPML069 The Control System Design of SCLF 4800
 
  • Y.B. Yan, J.G. Ding, G.Y. Jiang, Y.B. Lengpresenter
    SSRF, Shanghai, People's Republic of China
  • J.F. Chen
    SINAP, Shanghai, People's Republic of China
 
  The high-gain free electron lasers have given scientists hopes for new scientific discoveries in many frontier research areas. The Shanghai Coherent Light Facility (SCLF) was proposed by the central government of China on April 2017, which is a quasi-continuous wave hard X-ray free electron laser facility. The control system is responsible for the facility-wide device control, data acquisition, machine protection, high level database or application, as well as network and computing platform. It will be mainly based on EPICS to reach the balance between the high performance and costs of maintenance. The latest technology will be adopted for the high repetition rate data acquisition and feedback system. The details of the control system design will be reported in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML069  
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THPML070 Point Spread Function Study of Quasi-Monochromatic X-Ray Pinhole Camera at SSRF 4803
 
  • B. Gao, H.J. Chen
    SINAP, Shanghai, People's Republic of China
  • J. Chen, Y.B. Lengpresenter
    SSRF, Shanghai, People's Republic of China
 
  Since 2009 an X-ray pinhole camera that has been used to present the transverse beam size and emittance on diagnostic beam line of the storage ring at SSRF. The real beam size is a function of the image size of the CCD camera and point spread function (PSF) of the system. The performance of the measurement of the transverse electron beam size is given by the width of the PSF of X-ray pinhole camera. The contributions to the PSF width are the PSF of pinhole itself due to diffraction, and the PSF of the screen and camera. An X-ray monochromatic system has been established to measure the PSF accurately, and decrease the variation in the beam size between the theoretical values and the measured ones at SSRF. In this article, both calculated and measured PSF of quasi-monochromatic X-ray pinhole camera will be presented in detail.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML070  
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THPML071 Upgrade of Digital BPM Processor at DCLS and SXFEL 4807
 
  • L.W. Lai, F.Z. Chen, Y.B. Lengpresenter, T. Wu, Y.B. Yan
    SSRF, Shanghai, People's Republic of China
  • J. Chen
    SINAP, Shanghai, People's Republic of China
 
  A digital BPM processor has been developed at 2016 in SINAP for DCLS and SXFEL, which are FEL facilities built in China. The stripline BPM and cavity BPM processors share the same hardware platform and firmware, but the processing algorithms implemented in EPICS IOC on the ARM CPU are different. The capability of the ARM limits the processing speed to 10 bunches per second. Now the bunch rate of DCLS and SXFEL are going to increase from 10Hz to 50Hz. To meet the higher processing speed requirements, the processor firmware and software are upgraded in 2017. All BPM signal processing algorithms are implemented in FPGA, and EPICS IOC reads results only. After the upgrade, the processing speed reach 120 bunches per second. And this is also a good preparation for future Shanghai Hard-X ray FEL, which bunch rate is about 1MHz.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML071  
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THPML072 Injection Comparison using Bunch-by-Bunch Beam Size Measurement System at SSRF 4811
 
  • H.J. Chen, J. Chen, B. Gao, Y.B. Lengpresenter
    SINAP, Shanghai, People's Republic of China
 
  Injection transient process happens every 5-10 minutes in storage ring during normal top-up operating mode at SSRF, which is a proper window for machine status and injection performance evaluation. In the recent year, a bunch-by-bunch beam size measurement system has been implemented at SSRF, which has the capability to offer transverse bunch-by-bunch position and size information and is a powerful tool for injection study. In this paper, we summarize three injection study results from July 2017 to April 2018, including betatron oscillation amplitude, spectrum, horizontal tune and damping time comparison. The oscillation amplitude and temporal behavior of recent injection are all better than results before contributed to the injection optimization work during maintenance in 2018 winter. In addition, the principal component analysis method is also applied to further study the injection behavior in turn-by-turn or bunch-by-bunch direction to the refilled bucket.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML072  
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THPML073 Measurement of the RF Reference Phase Stability in the SuperKEKB Injector LINAC 4815
SUSPL063   use link to see paper's listing under its alternate paper code  
 
  • N. Liu
    Sokendai, Ibaraki, Japan
  • D.A. Arakawa, H. Katagiri, T. Matsumoto, S. Michizono, T. Miura, F. Qiu, Y. Yano
    KEK, Ibaraki, Japan
 
  The SuperKEKB injector is a more than 600 m J-shaped LINAC. The requirement of the RF phase refer-ence stability is 0.1 degree (RMS) at 2856 MHz for SuperKEKB PHASE-2 commissioning. In order to clari-fy and improve the reference line performance, the RF reference phase stability is measured. The phase noise of the RF reference at each sector is shown in this paper. A new phase monitor system is implemented to measure the short-term stability and long-term drift due to the temperature and humidity fluctuations in the klystron gallery.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML073  
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THPML074 Image Reconstruction Technique Based on Coded Aperture Imaging for SuperKEKB X-ray Beam Size Monitor 4819
SUSPF105   use link to see paper's listing under its alternate paper code  
 
  • E. Mulyani, J.W. Flanagan
    Sokendai, Ibaraki, Japan
  • J.W. Flanagan, H. Fukuma, H. Ikeda, M. Tobiyama
    KEK, Ibaraki, Japan
 
  The fast reconstruction techniques based on principles originally developed for coded aperture imaging have been investigated for SuperKEKB accelerator. The establishment of this technique will very important for measuring the beam sizes of all 2500 bunches in the SuperKEKB accelerator over thousands of turns, as needed for instability studies and luminosity tuning, due to the vast quantity of data that needs to be processed in a timely manner.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML074  
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THPML075 MYRRHA Control System Development 4823
 
  • R. Modic, M. Pavleski, T. Zagar
    Cosylab, Ljubljana, Slovenia
  • J. Belmans, P. Della Faille, D. Vandeplasschepresenter
    Studiecentrum voor Kernenergie - Centre d'Étude de l'énergie Nucléaire (SCK•CEN), Mol, Belgium
 
  MYRRHA ADS (Accelerator Driven System), the prototype of a nuclear reactor driven by a particle accelerator, is being realized through a staged approach. This paper will explore the Control System (CS) strategy for the current stage of the accelerator R&D, where the goal is injector for the energies up to 5.9 MeV. Accelerator components are being delivered within international semi-industrial partnerships. Currently the RFQ, MYRRHA's first RF structure, is being introduced. It will be followed by the first Medium Energy Beam Transport (MEBT1) and several normal-conducting CH cavities. As the portfolio and number of devices and systems grows there is increased push towards standardization of integration procedures, interfaces to system-wide services, configuration management. Several partners provide components with varying level of vertical integration. The responsibility of the Control System integrator is therefore shifting towards provision of integration guidelines, configuration and deployment of central services and management tools, training to the contributing developers, help with specifications and requirements, quality insurance and acceptance criteria.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML075  
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THPML076 Design of Control System for Dual-Head Radiation Therapy 4826
SUSPL059   use link to see paper's listing under its alternate paper code  
 
  • H.S. Kim, J.-S. Chai, M. Ghergherehchi, D.H. Ha, J.C. Lee, H. Namgoong, J.H. Seo, Shin, S.W. Shin
    SKKU, Suwon, Republic of Korea
  • D. Lipka
    DESY, Hamburg, Germany
 
  Sungkyunkwan University groups have been developed advanced radiation therapy machine named dual-head radiation therapy gantry for reducing the treatment time by up to 30%. The main difference between previous radiation therapy machine is using two electron LINAC as X-ray sources at radiation therapy. In support of this system, control system based on SCADA and hardware development was implemented. The control system consists of supervisory computers and local controllers and the control network was ethernet and software was written by labVIEW. An overview of this control system is presented in paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML076  
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THPML077 Status of the Machine Protection System for ARIEL e-linac 4829
 
  • M. Alcorta, D. Dale, H. Hui, S.R. Koscielniak, K. Langton, K. LeBlanc, M. Rowe
    TRIUMF, Vancouver, Canada
 
  The Advanced Rare Isotope & Electron Linac (ARIEL) facility at TRIUMF consists of an electron linear accelerator (e-linac) capable of currents up to 10 mA at an energy of 30 MeV, giving a total available beam power of 300 kW. In addition, the e-linac can be run in pulsed operation down to beam pulses of 5 µs, up to CW. A Machine Protection System (MPS) is required to protect the accelerator from hazardous beam spills and must turn off the electron gun within 10 µs of detection. The MPS consists of two types of beam loss monitors, a front-end beam loss monitor board developed at TRIUMF, and EPICS-based controls to establish operating modes. A trip time of 10 µs has been demonstrated, along with a 106 dynamic range and sensitivity down to 100 pA. This paper is focused on the current status of the beam loss monitor detection system.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML077  
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THPML078 Web-Based Control Room Applications at TRIUMF 4832
 
  • C.B. Barquest, P. M. Jung, S. Kiy, K.E. Lucow, T. Planche, S.D. Rädel, B.E. Schultz, D. Sehayek, O. Shelbaya, D. Tattan
    TRIUMF, Vancouver, Canada
  • M. Corwin, S. Marcano
    UW/Physics, Waterloo, Ontario, Canada
 
  Control room applications are programs that interface with control systems and beam physics models. These tools range from real-time diagnostic visualizations to post-processing data analysis. At TRIUMF, the concept of web-based control room applications has been adopted to advance the capabilities of these applications and facilitate operations. This online model takes advantage of server-based continuous integration and a centralized middleware layer. Continuous integration of server-based applications allows for easy deployment and maintenance. A centralized middleware layer allows a single application to work for many different accelerator configurations. Some motivating examples of web-based applications currenly being developed are presented, demonstrating this online approach to be an effective method for deploying applications for use in the control room and beyond.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML078  
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THPML079 Multipole Tuning Algorithm for the CANREB HRS at TRIUMF 4836
 
  • D. Sehayek, R.A. Baartman, C.B. Barquestpresenter, J.A. Maloney, M. Marchetto, T. Planche
    TRIUMF, Vancouver, Canada
 
  The TRIUMF CANadian Rare isotope facility with Electron Beam ion source (CANREB) High Resolution Separator (HRS) has been designed to separate rare isotopes with mass/charge differences of only one part in 20,000 for beams with transverse emittances of 3 μm. To reach this resolution, high-order aberrations must be corrected using a multipole corrector. From experience, tuning such a multipole is very challenging. The unique geometry of our multipole motivated a novel tuning method based on determining the desired pole voltages directly from measured emmitance. This novel tuning algorithm is presented alongside a web application which has been developed in anticipation of the commissioning of the HRS.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML079  
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THPML080 Preliminary Results of a New High Brightness H Ion Source Developed at TRIUMF 4839
 
  • K. Jayamanna, F. Ames, Y. Bylinskiipresenter, J.Y. Cheng, M. Lovera, M. Minato
    TRIUMF, Vancouver, Canada
 
  This paper describes the preliminary results of a high brightness ion source developed at TRIUMF, which is capable of producing a negative hydrogen ion beam (H) of up to 5 mA of direct current. A 1.7 mm.mrad and 5 mm.mrad emittance(rms) is achieved for 500 uA and for 1 mA H-, respectively. Characteristics as well as a brief description regarding extraction issues of the source to date are also presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML080  
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THPML081 Beam-Based Measurements of the ISAC-II Superconducting Heavy Ion Linac 4841
 
  • S. Kiy, R.E. Laxdal, M. Marchetto, S.D. Rädel, O. Shelbaya
    TRIUMF, Vancouver, Canada
 
  Preparation for experiments, which typically run for one to two weeks in the ISAC-II facility at TRIUMF, requires some amount of overhead, limiting the efficiency of the facility. Efforts are underway to improve the ISAC-II linac model to reduce this overhead while also improving the quality of the delivered ion beam. This can be accomplished with beam-based measurements and corrections of alignment, cavity gradients, focal strengths, and more. A review of the present state of the linac will be given, including measured mis-alignments and other factors that affect the reproducibility of tunes. The outlook on expected improvements will also be summarized, including progress on the automatic phasing of cavities with a focus on integration to the High Level Application platform being developed at TRIUMF. Lastly, a summary will be given on the expected paradigm shift in the tuning approach taken: moving from re-active tuning by operators or beam delivery experts to pro-active measurements and investigations, version-controlled tunes, and continuous feedback from beam physicists.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML081  
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THPML082 Reflected Power Based Extremum Seeking Control Algorithm to Tune the Resonance Frequency of Room Temperature Cavities 4844
 
  • R. Leewe, K. Fong, Z. Shahriari
    TRIUMF, Vancouver, Canada
  • M. Moallem
    SFU, Surrey, Canada
 
  A sliding mode extremum seeking algorithm to tune the resonance frequency was implemented in two of TRIUMF's DTL tanks. The tuning algorithm searches for the minimum reflected power point and was developed to eliminate the highly temperature dependent phase measurement, which was previously used to tune the resonance frequency. Short and long term measurement results show that the tuning algorithm compensates for the RF heating effect as well as for diurnal temperature variations. Reflected power measurements of TRIUMF's DTL tank 3 were taken for both cases of operating the phase based tuning system and the reflected power based tuning system, with an outcome of a higher tuning accuracy of the newly developed system. Another advantage is a quick cavity start up time, as the reflected power based system does not rely on a reference set point which has do be adjusted manually. The sliding mode extremum seeking control loop is currently commissioned in further room temperature cavities of the TRIUMF's ISAC I facility.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML082  
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THPML083 Iterative Learning Control to Cancel Beam Loading Effect on Amplitude and Phase of the Accelerating Field 4847
 
  • Z. Shahriari, K. Fong
    TRIUMF, Vancouver, Canada
  • G. A. Dumont
    UBC, Vancouver, Canada
 
  Funding: This research is supported by TRIUMF through federal funding via a contribution agreement with the National Research Council of Canada.
Iterative learning control (ILC) is an open loop control strategy that improves the performance of a repetitive system through learning from previous iterations. ILC can be used to compensate for a repetitive disturbance like the beam loading effect in resonators. Assuming that the beam loading disturbance is identical for all iterations, the learning law can be non-causal; it can anticipate the disturbance and preemptively counteract its effect. In this work, we aim to use ILC to cancel beam loading effect on amplitude and phase. Feedback controllers are not fast enough for this purpose. A normal feed forward controller may not be sufficient as well if there is a difference between the feed forward signal and the beam loading current. Therefore, the goal is to use ILC to adaptively cancel the beam loading effect.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML083  
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THPML084 Validating the COBEA Algorithm at the DELTA Storage Ring 4851
 
  • B. Riemann, B.D. Isbarn, S. Khan, S. Koetterpresenter, T. Weis
    DELTA, Dortmund, Germany
 
  Closed-Orbit Bilinear-Exponential Analysis (COBEA) is an algorithm to decompose monitor-corrector response matrices into (scaled) beta optics values, phase advances, scaled dispersion and betatron tunes. No explicit magnetic lattice model is required for COBEA - only the sequence of monitors and correctors along the beam path (no lengths, no strengths approach). To obtain absolute beta values, the length of one drift space can be provided as optional input. In this work, the application of COBEA to the DELTA storage ring, operated by TU Dortmund University, is discussed, and its results for betatron tunes and scaled dispersion are compared with those of conventional, direct measurement methods. COBEA is also put in a historical perspective to other diagnostic algorithms. Improvements in the Python implementation of COBEA, which is available as free software, are presented. Due to COBEA being relatively modest regarding its requirements on input data respectively hardware, it should be applicable to the majority of existing storage rings.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML084  
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THPML085 Intelligent Controls for the Electron Storage Ring DELTA 4855
 
  • D. Schirmer
    DELTA, Dortmund, Germany
 
  In recent years, artificial intelligence has become one of the buzzwords in the field of controlling, monitoring and optimizing complex machines. Particle accelerators belong to this class of machines in particular. In accelerator controls one has to deal with a variety of time-varying parameters, nonlinear dynamics as well as a lot of small, compounding errors. Therefore, to cope with these tasks and to achieve higher performance, particle accelerators require new advanced strategies in controls and feedback systems. Machine learning through (deep) neural networks, genetic algorithms, swarm intelligence and adaptive controls are some of the proposed approaches. Increased computational capability and the availability of large data sets in combination with better theoretical understanding of new network architectures and training paradigms allow for promising approaches for novel developments. This report aims to discuss the state of the art techniques and presents ideas for possible applications of intelligent controls at the synchrotron radiation source DELTA.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML085  
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THPML087 First ERL Operation of S-DALINAC and Commissioning of a Path Length Adjustment System 4859
 
  • M. Arnold, C. Burandt, R. Grewepresenter, J. Pforr, N. Pietralla, M. Steinhorst
    TU Darmstadt, Darmstadt, Germany
  • C. Eschelbach, M. Lösler
    Frankfurt University of Applied Sciences, Frankfurt am Main, Germany
  • F. Hug
    KPH, Mainz, Germany
 
  Funding: Work supported by DFG through GRK 2128 and INST163/383-1/FUGG
The S-DALINAC is running in recirculating operation since 1991. In 2015/2016 a major upgrade was performed by adding a third recirculation beam line. The versatility of this recirculation beam line enables a phase shift of the beam of up to 360° of the RF phase. The required range of 10 cm for a 3 GHz RF frequency is realized by a path length adjustment system. A complementary operation in normal scheme (single-pass, once or thrice recirculating with acceleration) or ERL mode (once or twice) is possible by appropriate adjustment of this system. After installation this system was aligned properly and its functionality and stroke was checked without beam. The system was commissioned by measuring the change of the beam phase in dependency of the setting of the path length adjustment system. The complementary usage of the newly installed recirculation for once recirculating with acceleration and once recirculating with ERL mode has been shown successfully in autumn 2017. This contribution will provide an overview on the path length adjustment system and the first run of the once recirculating ERL mode of the S-DALINAC.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML087  
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THPML088 Cavity Impedance Reduction Strategies During Multi Cavity Operation in the SIS100 High Intensity Hadron Synchrotron 4863
 
  • D. Mihailescu Stoica, D. Domont-Yankulova
    Technische Universität Darmstadt (TU Darmstadt, RMR), Darmstadt, Germany
  • D. Domont-Yankulova, H. Klingbeil
    TEMF, TU Darmstadt, Darmstadt, Germany
  • H. Klingbeil, D.E.M. Lens
    GSI, Darmstadt, Germany
 
  Funding: Supported by GSI Helmholtzzentrum für Schwerionenforschung GmbH
The planned SIS100 heavy ion synchrotron at the GSI Helmholtzzentrum für Schwerionenforschung will possess twenty ferrite accelerating cavities in its final stage of extension. As at injection and at flat top during slow extraction of the planned acceleration cycles the RF voltage will be relatively low, not all cavities will be active in this part of operation. It is important to analyse the impact of the inactive cavities on the overall RF voltage and subsequently their implication on the longitudinal particle dynamics. Classical approaches for reducing the beam impedance consist of active detuning of the cavities to pre-described parking frequencies. The fact that two out of ten buckets have to stay empty in all SIS100 scenarios is of particular interest as additional frequency components appear in the excitatory beam current, which have to be considered when the cavity is detuned. Therefore multi-cavity particle tracking simulations, consisting of twenty cavities and their attached LLRF control systems, are carried out in order to analyse different possibilities to minimize the impact on the beam dynamics and emittance growth.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML088  
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THPML089 Tuning of 3-tap Bandpass Filter During Acceleration for Longitudinal Beam Stabilization at FAIR 4866
 
  • B.R. Reichardt, D. Domont-Yankulova
    Technische Universität Darmstadt (TU Darmstadt, RMR), Darmstadt, Germany
  • D. Domont-Yankulova, H. Klingbeil
    TEMF, TU Darmstadt, Darmstadt, Germany
  • H. Klingbeil, D.E.M. Lens
    GSI, Darmstadt, Germany
 
  During acceleration in the heavy-ion synchrotrons SIS18/SIS100 at GSI/FAIR longitudinal beam oscillations are expected to occur. To reduce longitudinal emittance blow-up, dedi- cated LLRF beam feedback systems are planned. To date, damping of longitudinal beam oscillations has been demon- strated in SIS18 machine experiments with a 3-tap filter controller (e.g. *), which is robust in regard to control pa- rameters and also to noise. On acceleration ramps the control parameters have to be adjusted to the varying synchrotron frequency. Previous results from beam experiments at GSI indicate that a proportional tuning rule for one parameter and an inversely proportional tuning rule for a second parameter is feasible, but the obtained damping rate may not be opti- mal for all synchrotron frequencies during the ramp. In this work, macro-particle simulations are performed to evaluate, whether it is sufficient to adjust the control parameters pro- portionally (inversely proportionally) to the change in the linear synchrotron frequency, or if it is necessary to take more pa- rameters, such as bunch-length and synchronous phase, into account to achieve stability and a considerable high damping rate for excited longitudinal dipole beam oscillations. This is done for single- and dual-harmonic acceleration ramps.
* H. Klingbeil et al., "A Digital Beam-Phase Control System for Heavy-Ion Synchrotrons", in IEEE Transactions on Nuclear Science, vol. 54, no. 6, pp. 2604-2610, Dec. 2007.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML089  
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THPML090 Optical Beam Loss Monitors Based on Fibres for the CLARA Phase 1 Beam-Line 4869
 
  • A.S. Alexandrova, L.J. Devlin, V. Tzoganis, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • A.D. Brynes, F. Jackson
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • A.D. Brynes, F. Jackson, V. Tzoganis, C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • E. Effinger, E.B. Holzer
    CERN, Geneva, Switzerland
 
  Funding: Work supported by STFC Cockcroft Institute core Grant No. ST/G008248/1
Fibre based Optical Beam Loss Monitors (oBLMs) are on-line devices used in-situ to measure losses along a beam-line. The technology is based on the detection of Cherenkov radiation, produced inside quartz fibres placed alongside the beampipe, from the interaction of secondary showers generated from losses hitting the vacuum pipe. This contribution presents ongoing developments of an oBLM system installed along the Compact Linear Accelerator for Research and Applications (CLARA). The oBLM system consists of 4 channels which allows for sub-metre loss resolution with two dimensional coverage along the entirety of the beam line, as opposed to conventional localised BLM systems. The system was first commissioned to measure dark current from the injector. The ability of the system to locate longitudinal positions of known beam loss locations has also been measured and has shown excellent agreement. We present measurements acquired from the detector during regular operation and during dedicated beam tests. We also discuss the incorporation of the monitor into the accelerator diagnostics system and its use in assisting accelerator characterisation and performance.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML090  
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THPML091 Design of a High Gradient 60 GHz Dielectric Accelerating Structure 4873
SUSPF034   use link to see paper's listing under its alternate paper code  
 
  • D.Z. Cao, D. Dan, W. Gai, C.-X. Tang, H. Zha
    TUB, Beijing, People's Republic of China
 
  RF breakdown are the main limitation for the application of high gradient structures. Higher frequencies and shorter pulse length benefit the design of accelerating structure for the breakdown threshold of surface field is Es=f1/2 τ-1/4. Power source which generates very short V-band pulse with nearly hundred megawatt is now available. The paper presents the analysis of a V-band dielectric acceleration structure and power source. Future plan about RF transmission and power coupling of the whole structure will be discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML091  
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THPML092 Electromagnetic and Mechanical Design of High Gradient S-Band Accelerator in TTX 4876
 
  • D.Z. Cao, H.B. Chen, Y. C. Du, W. Gai, W.-H. Huang, J. Shi, C.-X. Tang, P. Wang, H. Zha
    TUB, Beijing, People's Republic of China
 
  Thomson scattering x-ray source is an essential scien-tific research tool in x-ray imaging technology for vari-ous fields. Upgrading plan of replacing the 3-meter S-band linac with a shorter structure operating at higher gradient in Tsinghua Thomson scattering X-ray source (TTX) is undergoing so far, aiming to enhance the accel-erating gradient from 15 MV/m to 30 MV/m. Detailed parameters of couplers and mechanical design of acceler-ation structure are presented in this work.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML092  
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THPML093 New Fast Kicker Results from the Muon g-2 E-989 Experiment at Fermilab 4879
 
  • A.P. Schreckenberger
    The University of Texas at Austin, Austin, Texas, USA
  • D. Barak, C.C. Jensen, G.E. Krafczyk, R.L. Madrak, H. Nguyen, H. Pfeffer, M. Popovic, J.C. Stapleton, C. Stoughton
    Fermilab, Batavia, Illinois, USA
  • A.T. Chapelain, A.A. Mikhailichenko, D. L. Rubin
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • N.S. Froemming
    CENPA, Seattle, Washington, USA
  • J.L. Holzbauer
    UMiss, University, Mississippi, USA
  • A.I. Keshavarzi
    The University of Liverpool, Liverpool, United Kingdom
 
  We describe the installation, commissioning, and characterization of the injection kicker system for the E-989 experiment at Fermilab for a precision measurement of the muon anomalous magnetic moment. Control and monitoring systems have been implemented to acquire and record the waveforms of each kicker pulse, and measurements of various kicker system observables were recorded in the presence of the 1.45 T g-2 storage ring magnetic field. These monitoring systems are necessary to understand the systematic contribution to the measurement of the precession frequency. We examine the dependence of muon capture to kicker field predictions.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML093  
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THPML094 New Methods for Dispersion Measurement and Correction for 12 GeV CEBAF 4882
 
  • D.L. Turner
    JLab, Newport News, Virginia, USA
 
  Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
This paper discusses methods for dispersion measurement and correction for the Continuous Electron Beam Accelerator Facility (CEBAF) for the 12GeV era. New methods will be compared with methods used during the 6GeV era. New software tools which implement the new methods will be discussed, along with a method for automating dispersion measurement and correction. New dispersion measurement and correction methods and tools are being implemented to provide more deterministic results and to reduce machine setup time.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML094  
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THPML095 Improvement of Wire-Stretching Technique to the RF Measurements of E-Center and Multipole Field for the Dipole Cavities 4885
 
  • G.-T. Park, J. Guo, H. Wang
    JLab, Newport News, Virginia, USA
  • A. Overstreet
    ODU, Norfolk, Virginia, USA
  • B. P. Xiaopresenter, T. Xin
    BNL, Upton, Long Island, New York, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
After the first publication* of wire-stretching technique from its principle to measure the electrical center of a deflecting cavity, more refinements of this techniques including the review of its analytical and simulation results, RF circuit improvement to improve the signal to noise ratio and its application to other cavities have been developed. These applications include the electrical center measurements for the LHC RFD and DQW crabbing cavity prototypes, multi-frequency harmonic kicker cavity for JLEIC electron cooler**, TE011 cavity developed for the beam magnetization measurement***, and a separator cavity at BNL****. Further development of measurement calibration, error reduction, alignment of cavity installation to the machine beam line, and multipole field analysis for the beam dynamics will be presented.
*H. Wang, Proceedings of NAPAC2016, pp225-228
**S. A. Overstreet, BS Thesis 2017, Guilford College, Greensboro, NC
***J. Guo et al. these proceedings
****T. Xin et al, these proceedings
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML095  
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THPML096 A Non-Invasive Magnetic Momentum Monitor Using a TE011 Cavity 4889
 
  • J. Guo, J. Henry, M. Poelker, R.A. Rimmerpresenter, R. Suleiman, H. Wang
    JLab, Newport News, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC with Laboratory Directed Research and Development funding, under U.S. DOE Contract No. DE-AC05-06OR23177.
The Jefferson Lab Electron-Ion Collider (JLEIC) design relies on cooling of the ion beam with bunched electron beam. The bunched beam cooler complex consists of a high current magnetized electron source, an energy recovery linac, a circulating ring, and a pair of long solenoids where the cooling takes place. A non-invasive real time monitoring system is highly desired to quantify electron beam magnetization. The authors propose to use a passive copper RF cavity in TE011 mode as such a monitor. In this paper, we will show the mechanism and scaling law of this device, as well as the design and testing results of the prototype cavity.
 
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THPML098 Design of Beam Profile Monitor Used at the Xi'an Proton Application Facility (XiPAF) 4892
 
  • D. Wang, Z.M. Wang
    State Key Laboratory of Intense Pulsed Radiation Simulation and Effect, Northwest Institute of Nuclear Technology, Shannxi, People's Republic of China
  • W. Chen
    NINT, Xi'an, People's Republic of China
  • P.F. Mapresenter, Y.G. Yang
    TUB, Beijing, People's Republic of China
  • W. Wang
    Tsinghua University, Beijing, People's Republic of China
 
  A pixel ionization chamber for beam profile monitor (BPrM) is designed and manufactured by a new technology .The detector will be installed on the beam line just upstream of the target device of XiPAF. It has many advantages such as high resolution, high radiation hardness and it can work as a real-time monitor to show the distribution of the delivered relative dose. The physics design and construction of the detector are described in this paper, and its performances are tested offline.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML098  
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THPML099 Phase Extraction and Stabilization for Coherent Pulse Stacking 4895
SUSPL060   use link to see paper's listing under its alternate paper code  
 
  • Y.L. Xu, W.-H. Huang, C.-X. Tang, L.X. Yan
    TUB, Beijing, People's Republic of China
  • L.R. Doolittle, Q. Du, G. Huang, W. Leemans, D. Li, R.B. Wilcox, Y. Yang, T. Zhou
    LBNL, Berkeley, California, USA
  • A. Galvanauskas
    University of Michigan, Ann Arbor, Michigan, USA
 
  Funding: This work was supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics, under Contract DE-AC02-05CH11231.
Coherent pulse stacking (CPS) is a new time-domain coherent addition technique that stacks several optical pulses into a single output pulse, enabling high pulse energy and high average power. We model the CPS as a digital filter in the Z domain, and implement two deterministic algorithms extracting the cavity phase from limited data where only the pulse intensity is available. In a 2-stage 15-pulse CPS system, each optical cavity is stabilized at an individually-prescribed round-trip phase with 0.7 deg and 2.1 deg RMS phase errors for Stage 1 and Stage 2 respectively. Optical cavity phase control with nm accuracy ensures 1.2% intensity stability of the stacked pulse over 12 hours.
 
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THPML100 A High Voltage Feedforward Subsystem of Low Level RF System for the High Power RF System 4898
SUSPL062   use link to see paper's listing under its alternate paper code  
 
  • Z.Y. Lin, Y. C. Du, H.Q. Fengpresenter, W.-H. Huang, CY. Song, C.-X. Tang, Y.L. Xu, J. Yang
    TUB, Beijing, People's Republic of China
  • G. Huang
    LBNL, Berkeley, California, USA
 
  The Low Level Radio Frequency control (LLRF) system measures the RF signals from the accelerator tube, compares it with the phase reference received from the timing distribution system, and provides the drive signal to the high power RF system to provide synchronized RF voltage to the electron beam. Usually, the LLRF system can achieve a ~50 fs RMS phase jitter which is limited by the microwave devices. The phase noise arise from the high voltage variation of the high power system will significantly increase phase noise from low level RF signal to high power RF. A high voltage feed forward subsystem is proposed to deal with the phase noise caused by the high voltage jitter of the modulator. The demo system is depolyed in Thomson scattering X-ray source (TTX).and the primary experiment result anaylse is discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML100  
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THPML101 A Novel Double Sideband-Based Phase Averaging Line for Phase Reference Distribution System 4901
 
  • Z.Y. Lin, Y.-C. Du, W.-H. Huang, Z. Panpresenter, C.-X. Tang, C.-X. Tang, Y.L. Xu, J. Yang
    TUB, Beijing, People's Republic of China
  • G. Huang
    LBNL, Berkeley, California, USA
 
  Coaxial cable based solution is one of the most important scheme in Phase Reference Distribution System. A novel double sideband-based phase averaging line has been developed in Tsinghua accelerator lab. The sender chassis generates the 2856 MHz signal as the forward signal and receives the 2856 MHz signal and the reflected double sideband signal from the receiver. The forward signal is phase-locked with the reference signal, and the forward signal and the sideband signal are adjusted by the FPGA virtual delay line. The preliminary experiments result shows the phase stability can achieve about 1% by signal distorted by the phase shifter.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML101  
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THPML102 Field and Cost Optimization of a 5 T/m Normal Conducting Quadrupole for the 10-MeV Beam Line of the eLINAC of the Mexican Particle Accelerator Community 4905
SUSPL080   use link to see paper's listing under its alternate paper code  
 
  • D. Chavez Valenzuela, G.H.I. Maury Cuna, M. Napsuciale Mendivil
    Universidad de Guanajuato, División de Ciencias e Ingenierías, León, Mexico
  • J. C. Basilio Ortiz
    CINVESTAV, Mexico City, Mexico
  • P.M. McIntyre, A. Sattarov
    Texas A&M University, College Station, USA
  • C.A. Valerio
    ECFM-UAS, Culiacan, Sinaloa, Mexico
  • B. Yee-Rendón
    KEK, Ibaraki, Japan
 
  The Mexican Particle Accelerator Community is currently designing the first Mexican RF eLINAC that will have three beamlines at 10, 60 and 100 MeV. In this work, we present an optimized design in terms of field quality and production cost for the 5 T/m normal conducting quadrupoles of the 10-MeV beamline. Several candidate materials for the yoke were studied based on their availability and machinability, with the aim to optimize in-house production cost (Mexico) while restricting a low multipole content.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML102  
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THPML106 Electron Microscopy Inspired Setup for Single-Shot 4-D Trace Space Reconstruction of Bright Electron Beams 4909
 
  • J. Giner Navarro, D.B. Cesarpresenter, P. Musumeci
    UCLA, Los Angeles, California, USA
  • R.W. Aßmann, B. Marchetti, D. Marx
    DESY, Hamburg, Germany
 
  Funding: This work has been partially supported by the National Science Foundation under Grant No. 1549132 and Department of Energy under award No. DE-SC0009914.
In the development of low charge, single-shot diagnostics for high brightness electron beams, Transmission Electron Microscopy (TEM) grids present certain advantages compared to pepper pot masks due to higher beam transmission. In this paper, we developed a set of criteria to optimize the resolution of a point projection image. However, this configuration of the beam with respect to the grid and detector positions implies the measurement of a strongly correlated phase space which entails a large sensitivity to small measurement errors in retrieving the projected emittance. We discuss the possibility of an alternative scheme by inserting a magnetic focusing system in between the grid and the detector, similar to an electron microscope design, to reconstruct the phase space when the beam is focused on the grid.
 
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THPML107 Steering Optimizations for the University of Maryland Electron Ring 4913
SUSPL053   use link to see paper's listing under its alternate paper code  
 
  • L. Dovlatyan, B.L. Beaudoin, R.A. Kishek, K.J. Ruisard
    UMD, College Park, Maryland, USA
 
  Funding: This work is supported by the US Dept. of Energy, Office of High Energy Physics award # DE-SC0010301
The University of Maryland Electron Ring (UMER) has the flexibility to set up alternative lattices for different research experiments, including nonlinear optics studies using octupoles. Each alternative lattice requires an acceptable steering solution for use in experiments. Existing beam-based alignment tools can take a significant amount of time to run and become difficult to process with a low number of BPMs. The Robust Conjugate Directional Search (RCDS) optimizer* is used to quickly obtain steering solutions for different lattice configurations and has been adopted for beam steering at UMER. Steering magnets are optimized online to reduce scraping, correct equilibrium orbits, and increase beam lifetimes. This study presents the application of the optimizer at UMER.
* X. Huang, J. Corbett, J. Safranek, J. Wu, Nucl. Instr. Meth. A vol. 726, pp. 77-83, 2013.
 
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THPML108 Distributed I/O System Based on Ethernet POWERLINK Under the EPICS Architecture 4917
SUSPL055   use link to see paper's listing under its alternate paper code  
 
  • X.K. Sun, G. Liu, Y. Song
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  Ethernet POWERLINK (EPL) is a communication profile for Real-Time Ethernet. The communication profile meets real-time demands for the distributed system composed of multiple controllers. EPICS is a wildly used distributed control system in large scientific facilities. We design a distributed IO system based on EPL under the EPICS architecture and establish the prototype system composed of a PC and six FPGA boards. In this system, an EPICS driver based on openPOWERLINK is developed to monitor the system status. In this paper, the communication mechanism of EPL, the design of system architecture, the implementation of EPICS driver and the test results of prototype system will be described.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML108  
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THPML109 Control System Design for Front End Devices of IRFEL 4920
 
  • S. Xu, G. Liu, Y. Song, X.K. Sunpresenter
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  An Infrared Free Electron Laser Light (IRFEL) is being constructed at National Synchrotron Radiation Laboratory. IRFEL consists of e-gun, accelerating tube, microwave, klystron, power supply, vacuum, resonator, undulator, beam diagnosis, cooling water and other devices. The development of the control system for the front end devices of IRFEL is based on EPICS. This paper will introduce the hardware system design, Input Output Controller application, Operation Interface, data archiving and retrieval.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML109  
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THPML110 EPICS Driver for Siemens CP1616 Communication Module 4923
 
  • Z. Huang, G. Liu, Y. Song, X.K. Sunpresenter
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  Funding: Work supported by National Natural Science Foundation of China (11375186)
Siemens communication module CP1616 is a high-performance PROFINET controller, which can support both Real-time (RT) and Isochronous Real-Time (IRT) communication. Experimental Physics and Industrial Control System (EPICS) is a wildly used distributed control system in large scientific devices. In order to integrate PROFINET protocol into EPICS environment, we developed this driver based on CP1616 and established the prototype system. This paper will describe the design of EPICS driver for CP1616 and the test result of the prototype system.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML110  
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THPML111 Test of the Tune Measurement System Based on BBQ at HLS-II Storage Ring 4926
 
  • L.T. Huang, F.L. Gao, P. Lu, B.G. Sun, H.Q. Wang, J.G. Wang, Q. Wang, F.F. Wu, Y.L. Yangpresenter, T.Y. Zhou
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  Funding: Supported by the National Science Foundation of China (Grant No. 11705203, 11575181)
The HLS-II storage ring is a crucial part of Hefei Light Source. Tune is one of the most important parameters of the electron storage ring, of which the tune measurement system is an integral component. In this paper, the design of a new tune measurement system based on BBQ (base band tune), is presented. Some experiments are performed to test this system. The new system is compared with the original system and the TBT (turn-by-turn) method respectively. The obtained results illustrate higher accuracy and higher stability for the new system. A new approach of calculating the betatron oscillation amplitude is proposed, and the betatron oscillation amplitudes in the normal running stage for the HLS-II storage ring are estimated at 95 nm (horizontal) and 60 nm (vertical).
 
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THPML112 Preliminary Design and Calculation of Button BPM for the HALS Storage Ring 4929
 
  • F.F. Wu, F.L. Gao, L.T. Huang, X.Y. Liu, P. Lu, B.G. Sun, J.H. Wei, Y.L. Yangpresenter, T.Y. Zhou
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  • L. Lin
    Huizhou University, Huizhou, People's Republic of China
 
  Funding: Supported by the National Science Foundation of China (Grant No.11705203, 11575181,11605202) and the National Key Research and Development Program of China(No. 2016YFA0402000)
Button BPM is being designed for the HALS storage ring, which is a diffraction-limited storage ring (DLSR) located at the NSRL in Hefei city. Since beam size is very small, the required resolution of 50 nm for beam position measurement need to be obtained. The parameters of the HALS Button BPM are initially determined. According to theoretical formulas, electrode induced signal is calculated and the relationship between electrode induced signal and beam current is obtained. Signal to noise ratio(SNR)of the HALS Button BPM is calculated with different beam current when the required resolution is 50 nm. The results show that the SNR is well when beam current is very low. In addition, the effects of BPM RF frequency and button electrode radius on SNR are analyzed.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML112  
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THPML113 Design and Simulation of the Waveguide Coupler for the Cavity Beam Monitor 4932
 
  • Q. Wang, Q. Luo, B.G. Sun, F.F. Wu, Y.L. Yangpresenter, Z.R. Zhou
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  • Y.W. Wu
    USTC, Hefei, Anhui, People's Republic of China
 
  Funding: Supported by The National Key Research and Development Program of China (2016YFA0401900), NSFC (11375178, 11575181) and the Fundamental Research Funds for the Central Universities (WK2310000046)
The waveguide coupling is an important way to extract the signals of the specific eigenmodes required. The design of the waveguide coupler, including the waveguide-to-coaxial adapter behind it for the cavity bunch length monitor is presented. The influence of the dimension parameters is analyzed, which offers the theoretical support for the design and application of cavity bunch length monitor or cavity beam position monitor (CBPM). A series simulation based on CST is performed to verify the feasibility, and the simulation results show good performance.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML113  
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THPML115 Introduction of the Laser Intensity Measurement System for the FELiChEM 4936
 
  • F.L. Gao, L.T. Huang, P. Lu, B.G. Sun, J.G. Wang, F.F. Wu, Y.L. Yangpresenter, T.Y. Zhou
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  The FELiChEM is a new infrared free electron laser (IR-FEL) facility, which is being built in the National Synchrotron Radiation Laboratory (NSRL) in Heifei, China. The facility will provide continuously tunable pulsed laser radiation covering the mid-infrared (MIR) wavelength range from 2.5 to 50μm and the far-infrared (FIR) range from 40 to 200μm. The output macro pulsed laser width is 5-10μs and pulsed laser power is 2-10kW. In order to evaluate pulsed laser saturation time and FEL optical cavity losses, the rise time and fall time of macro pulsed laser need to be measured. Laser intensity measurement system for the FELiChEM is being designed. This system is composed of optical system, pyroelectric detector and electronics. Each module will be described in detail in this paper. The laser intensity measurement system was tested under offline and online conditions. The results showed that pulsed laser of 10μs width can be measured and the design requirement can be met with this system.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML115  
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THPML116 AutoTuner: A General Graphical User Interface for Automated Tuning 4939
 
  • X. Huang
    SLAC, Menlo Park, California, USA
  • T. Zhangpresenter
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  AutoTuner is a general graphical user interface (GUI) that we developed for automated tuning or online optimization. The GUI provides a convenient interface to select tuning knobs, objectives, and optimization algorithms and to change the tuning control parameters. Tuning setup can be created and saved for reuse. The progress of the tuning processing is plotted in real time. The tuning process can be paused, aborted, or resumed. We have tested the program for real-life accelerator tuning problems.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML116  
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THPML117 Study of the Impact of Linear Coupling on Off-Axis Injection 4943
 
  • X. Huang
    SLAC, Menlo Park, California, USA
  • T. Zhangpresenter
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  The next generation of storage ring light sources will likely operate with high linear coupling, which could potentially prevent the use of off-axis injection as large horizontal oscillation of the injected beam is coupled to the vertical plane. We did experiments on the SPEAR3 storage ring to study how linear coupling impact the dynamic aperture and the off-axis injection efficiency. The results show that the dynamic aperture is significantly reduced and injection efficiency can drop to zero when operated on the coupling resonance. However, with large nonlinear detuning, the dynamic aperture and high injection efficiency can survive with the stored beam at full coupling because the injected beam is shifted away from the coupling resonance.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML117  
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THPML118 The AWAKE Electron Spectrometer 4947
 
  • F. Keeble, M. Cascella, J. A. Chappell, L.C. Deacon, S. Jolly, M. Wing
    UCL, London, United Kingdom
  • I. Gorgisyan, S. Mazzoni
    CERN, Geneva, Switzerland
  • P.L. Penna, M. Quattri
    ESO, Garching bei Muenchen, Germany
 
  The AWAKE experiment at CERN aims to use a proton driven plasma wakefield to accelerate electrons from 10–20 MeV up to GeV energies in a 10 m plasma cell. We present the design of the magnetic spectrometer which will measure the electron energy distribution. Results from the calibration of the spectrometer's scintillator and optical system are presented, along with a study of the backgrounds generated by the 400 GeV SPS proton beam.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML118  
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THPML119 A Time-of-Flight Based Energy Measurement System for the LIGHT Medical Accelerator 4951
SUSPF096   use link to see paper's listing under its alternate paper code  
 
  • F. Galizzi
    University of Bergamo, Bergamo, Italy
  • M. Caldara, F. Galizzi, A. Jeff
    A.D.A.M. SA, Meyrin, Switzerland
 
  The LIGHT proton therapy facility is the first compact Linac that will deliver proton beams up to 230 MeV for cancer treatment. The proton beam is pulsed; pulses repetition rate can reach 200 Hz. LIGHT prototype is currently being commissioned by AVO/ADAM at CERN, while the first full installation is foreseen in 2019. Beam energy translates directly to range penetration in the body, so it is of the utmost importance to monitor it accurately especially for Linacs, since each beam pulse is directly transported to the patient. We present the implementation of a non-interceptive beam energy measurement system based on the Time-of-Flight technique. Unlike state of the art ToF systems this one has been designed to measure autonomously the mean energy of the beam with medical resolution (0.03 %) by processing as little as 1 us of data providing the result within 1 to 2 ms over an energy range from 5 to 230 MeV. The first results for beams up to 7.5 MeV are shown.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML119  
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THPML120 Development of Coating Technique for Superconducting Multilayered Structure 4954
 
  • R. Ito, T. Nagata
    ULVAC, Inc, Chiba, Japan
  • H. Hayano, T. Kubo, T. Saeki
    KEK, Ibaraki, Japan
  • H. Ito
    Sokendai, Ibaraki, Japan
  • Y. Iwashita, R. Katayama
    Kyoto ICR, Uji, Kyoto, Japan
  • H. Oikawa
    Utsunomiya University, Utsunomiya, Japan
 
  In order to increase the maximum acceleration gradient of SRF cavities, S-I-S (superconductor-insulator-superconductor) multilayered structure theory has been proposed. We focused on NbN which has a higher superconducting transition temperature than Nb. Firstly, we researched the optimal deposition condition for N2 gas reactive sputtering of NbN by using in-house inter-back type DC magnetron sputtering equipment. The critical condition for a thin film with strong crystalline orientation of NbN was identified. The superconducting transition temperature of the NbN thin film, which were coated under the best condition, was over 14 K. Secondly, we tried making S-I-S multilayered samples that was composed of NbN/SiO2/Nb substrate. The coating condition for the NbN layer was determined based on the research results in a single layer. The SiO2 layer was deposited with a film thickness of 30 nm that was theoretically expected to be effective as barrier layer. We applied O2 gas reactive AC magnetron sputtering for coating. In this article, the detailed results of the NbN single layer and multilayer film depositions are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML120  
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THPML121 Compensation of Transient Beam Loading in Ramping Synchrotrons Using a Fixed Frequency Processing Clock 4957
SUSPL061   use link to see paper's listing under its alternate paper code  
 
  • F.J. Galindo Guarch, J.M.M.A. Moreno Arostegui
    Universitat Politécnica de Catalunya, Barcelona, Spain
  • P. Baudrenghien, F.J. Galindo Guarch
    CERN, Geneva, Switzerland
 
  Transient beam loading compensation schemes, such as One-Turn-FeedBack (OTFB), require beam synchronous processing (BSP). Swept clocks derived from the RF, and therefore harmonic to the revolution frequency, are widely used in CERN synchrotrons; this simplifies implementation with energy ramping, where the revolution frequency changes. It is however not optimal for state-of-the-art digital hardware that prefers fixed frequency clocks. An alternative to the swept clocking is the use of a deterministic protocol, for example, White Rabbit (WR): a fixed reference clock can be extracted from its data stream, while enabling digital distribution of the RF frequency among other data. New algorithms must be developed for BSP using this fixed clock and the digital data transmitted on the WR link. This is the strategy adopted for the SPS Low Level RF (LLRF) upgrade. The paper gives an overview of the technical, technological and historical motivations for such a paradigm evolution. It lists the problems of fixed clock BSP, and presents an innovative solution based on a real-time variable ratio re-sampler for implementing an OTFB with the new fixed clock scheme.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML121  
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THPML122 Beta-SRF - A New Facility to Characterize SRF Materials near Fundamental Limits 4961
SUSPL077   use link to see paper's listing under its alternate paper code  
 
  • E. Thoeng
    UBC & TRIUMF, Vancouver, British Columbia, Canada
  • R.A. Baartman, R.E. Laxdal, B. Matheson, G. Morris, N. Muller, S. Saminathan
    TRIUMF, Vancouver, Canada
  • A. Chen
    UBC, Vancouver, Canada
  • T. Junginger
    Lancaster University, Lancaster, United Kingdom
 
  Funding: Natural Sciences and Engineering Research Council of Canada (NSERC) & UBC (NSERC) IsoSiM Program
Demands of CW high-power LINAC require SRF cavities operating at the frontier of high accelerating gradient and low RF power dissipation, i.e. high quality factor (Q0). This requirement poses a challenge for standard surface treatment recipes of SRF cavities. In a recent breakthrough, elliptical SRF cavities doped with Nitrogen have been shown to improve Q0 by a factor of 3, close to the fundamental SRF limit. The fundamental mechanisms at microscopic level and optimum doping recipe, however, have still not fully been understood. Materials other than Nb have also been proposed for SRF cavities to overcome the fundamental limit already reached with Nitrogen doping, e.g. Nb3Sn, MgB2, and Nb-SIS multilayer. At TRIUMF, a unique experimental facility is currently being developed to address these issues. This facility will be able to probe local surface magnetic field in the order of the London Penetration Depth (several tens of nm) via \beta decay detection of a low-energy radioactive ion-beam. This allows depth-resolution and layer-by-layer measurement of magnetic field shielding effectiveness of different SRF materials at high-parallel field (up to 200 mT). Design and current development of this facility will be presented here, as well as commissioning and future measurements strategies for new SRF materials.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML122  
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THPML123 The ESR Barrier-Bucket LLRF System - Design and First Results 4964
 
  • J. Harzheim, D. Domont-Yankulova, K. Groß, H. Klingbeil
    TEMF, TU Darmstadt, Darmstadt, Germany
  • M. Frey, H. Klingbeil, D.E.M. Lens
    GSI, Darmstadt, Germany
 
  At GSI, Darmstadt, Germany, a Barrier-Bucket (BB) RF System is currently under development for the Experimental Storage Ring (ESR). The system consists of two broadband RF cavities, each driven by a solid state amplifier, with the purpose to produce two voltage pulses per beam revolution. This will enable highly sophisticated longitudinal beam manipulations like longitudinal capture, compression and decompression or stacking of the beam. For the LLRF System, several requirements have to be fulfilled. Besides high standards concerning the pulsed gap signal quality (e.g. ringing <2.5%), the system has to provide the flexibility for adiabatic voltage ramp-up and adiabatic pulse shifting with high timing accuracy. A connection to the FAIR Central Control System (CCS) is necessary, as amplitude and phase ramp data will be provided by the CCS. In this contribution, the structure of the ESR BB LLRF system is presented together with experimental results from the first version of the system, which will be installed in the ESR in March 2018.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML123  
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THPML124 Design of Beam Position Fast-Correction Magnet Power Supply for HALS 4967
SUSPL082   use link to see paper's listing under its alternate paper code  
 
  • Z.X. Shao, H. Gao, L. Wang, H.Y. Zhang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  Funding: Supported by 'Hefei Advanced Light Source Pre-research Project'
Hefei Advanced Light Source (HALS) is the fourth-generation radiation light source that is being pre-researched in China. Ultra-low emittance of the beam requires higher performance of power supply system. We designed a fast correcting power supply for the beam measurement needs. We adopted the all-digital method, the current closed-loop feedback used the AD7766 with 24-bit resolution as its A/D converter. And we added the corresponding constant temperature control, chain protection, etc. The small-signal frequency response of this system can reach more than 5kHz. The detail design scheme is described in this paper.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML124  
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THPML125 Efficiency Analysis of High Average Power Linacs for Environmental and Industrial Applications 4970
 
  • M. Shumail, V.A. Dolgashev
    SLAC, Menlo Park, California, USA
 
  Funding: U.S. Department of Energy, HEP under Research Opportunities in Accelerator Stewardship: LAB 16-1438.
We present comprehensive efficiency equations and useful scaling laws to optimally determine design parameters for high efficiency rf linacs. For the first time we have incorporated the parasitic losses due to the higher order cavity modes into the efficiency analysis of the standing wave (SW) and travelling wave (TW) accelerators. We have also derived the efficiency equations for a new kind of attenuation-independent-impedance travelling wave (ATW) accelerators where the shunt impedance can be optimized independent of the group velocity. We have obtained scaling laws which relate the rf to beam efficiency to the linac length, beam aperture radius , phase advance per cell, and the type of accelerating structure: SW versus TW, disk-loaded (DL) versus nose-cone (NC). We give an example of using these scaling laws to determine a feasible set of parameters for a 10 MeV, 10 MW linac with 97.2% efficiency.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML125  
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THPML126 Design of High Efficiency High Power CW Linacs for Environmental and Industrial Applications 4974
 
  • M. Shumail, V.A. Dolgashev, C.M. Markusen
    SLAC, Menlo Park, California, USA
 
  Funding: US Department of Energy, Office of High Energy Physics, through Accelerator Stewardship Grant
We have used our accelerator design toolbox equations to design three high efficiency and high power CW accelerators for the environmental and medical applications. These are: 2MeV-1MW, 10MeV-10MW, and 10MeV-1MW linacs. These are all 10 m long, 1.3 GHz, π-mode standing wave structures with design efficiencies of 96.8, 97.4 and 86.5 %, and optimal coupling coefficients of 32.9, 43.5, and 7.45, respectively. We present the detailed design parameters of these linacs. The study of single-bunch beam breakup for these linacs and the simulations results from ABCI are also included. The initial cavities are optimized according to the speed of the electron bunch to maximize the shunt impedance. The plots of peak surface fields on these cavities are also presented. We have also included a detailed thermal analysis of these linacs. Finally, we present the results of ASTRA simulations of the three linacs with magnetic focusing. We have also included the complete design of rf-distributed-coupling manifold for the third linac along with the HFSS® simulation results.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML126  
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THPML127 Alignment and Installation for the FELiChEM project 4977
 
  • W. Wang, Zhang, H.T. H.T, X.Y. He, D.R. Xu
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  Funding: Work supported by National Natural Science Foundation of China (11705199) and China Postdoctoral Science Foundation (2017M622024)
FELiChEM is a new experimental facility under construction at the University of Science and Technology of China. There are more than one hundred important devices to construct it, which core device is two free electron laser oscillators generating middle-infrared and far-infrared laser and covering the spectral range of 25-200μm. The optical cavity is an important component of oscillator which very sensitive to misalignment errors of the mirror, due to its near-concentric and symmetric structure. High precision alignment and installation is necessary to ensure the smooth implementation of the FELiChEM project. Laser tracker and Level are used to install this devices according to the alignment control network. An efficient and high-precision alignment method based on autocollimator and photoelectric auto-collimator is used to align optical cavity of oscillator. This methods is proven to be effective and meet the tolerances by multiple means.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML127  
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THPML128 Production and Secondary Electron Yield Test of Amorphous Carbon Thin Film 4980
 
  • Y.X. Zhang, X.Q. Ge, S.W. Wangpresenter, Y. Wang, W. Wei, B. Zhang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  Amorphous carbon (a-C) thin film applied to vacuum chambers of high-energy particle accelerators can decrease secondary electron yield(SEY)and suppress electron-cloud effectively. A dc magnetron sputtering apparatus to obtain a-C film has been designed. With the equipment, a-C thin film can be deposited on the inner face of stainless steel pipes ultimately which is uniform and high-quality. Meanwhile, it is found that a-C has a low SEY<1.2 measured by the secondary electron emission measurement set-up in the National Synchrotron Radiation Laboratory. The result indicates that a-C is an ideal material for modern accelerators.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML128  
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THPML129 Deposition and Characterization of TiZrHfV films by DC Magnetron Sputtering 4983
 
  • X.Q. Ge, T.L. Hepresenter, X.T. Pei, Y.G. Wang, Y. Wang, W. Wei, B. Zhang, Y.X. Zhang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  The new generation of accelerators places higher demands on the surfaces of vacuum chamber materials. Search for low secondary electron yield (SEY) materials and an effective vacuum chamber surface treatment process, which can effectively reduce the electronic cloud effect, are important early works for the new generation of accelerators. In this work, we revealed the SEY characteristics of Ti-Zr-Hf-V NEG films and Ti-Zr-V NEG films which were deposited on Si (111) substrates using direct current magnetron sputtering method. The surface morphology and surface chemical bonding information were collected by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). With the same parameters, the maximum SEY of Ti-Zr-Hf-V NEG films and Ti-Zr-V NEG films are 1.24 and 1.51, respectively. These results are of great significance for the next-generation particle accelerators.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML129  
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THPML130 Applications of a Distributed Beam Loss Monitor at the Australian Synchrotron 4986
SUSPF097   use link to see paper's listing under its alternate paper code  
 
  • P.J. Giansiracusa, T.G. Lucas, R.P. Rassool, M. Volpi
    The University of Melbourne, Melbourne, Victoria, Australia
  • M.J. Boland
    CLS, Saskatoon, Saskatchewan, Canada
  • G. LeBlanc
    SLSA, Clayton, Australia
 
  A distributed beam loss monitoring system, based on Cherenkov silica fibres, has been installed at the Australian Synchrotron. The fibres are installed parallel to the beam pipe and cover the majority of the injection system and storage ring. Relativistic charged particles from beam loss events that have a velocity above the Cherenkov threshold produce photons in the fibres. These photons are then guided along the fibres to detectors outside of the accelerator tunnels. Originally the system was installed to determine its suitability for measuring losses at a future linear collider, such as the Compact Linear Collider, with single pass 150 ns bunch trains. This study builds on these results and attempts to use the system to measure loss locations with a circulating beam. We present the preliminary results and describe how the system could be improved.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML130  
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THPML131 A NEW PRODUCTION PROCESS FOR UCx TARGETS FOR RADIOACTIVE ISOTOPE BEAMS AT TRIUMF 4990
SUSPL087   use link to see paper's listing under its alternate paper code  
 
  • M. S. Cervantes, P. Fouquet-Métivier, A. Gottberg, P. Kunz, L. Lambert, A. Mjøs, J. Wong
    TRIUMF, Vancouver, Canada
  • M. S. Cervantes
    UVIC, Victoria, Canada
  • P. Fouquet-Métivier
    ENSCM, Montpellier, France
  • A. Gottberg
    Victoria University, Victoria, B.C., Canada
 
  TRIUMF has the objective of producing radioactive isotope beams (RIB) using the ISOL method. Radioactive isotopes are used in experiments in different areas of science. At the TRIUMF-ISAC facility, a 500 MeV proton driver beam impinges onto different targets and induces nuclear reactions in them. The isotopes obtained in this way then diffuse out of the target material before they are ionized and extracted to form an isotope beam. Targets of uranium carbide with excess of graphite (UCx) are the most requested targets at TRIUMF. ARIEL, TRIUMF's flagship project, aims at increasing the radioactive isotope production capabilities to satisfy the growing demand of radioactive isotopes. The current production method of UCx targest does not have the means to supply enough UCx targets to satisfy ARIEL's demand, therefore, a new method for efficient UCx target material synthesis is being developed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML131  
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THPML132 Cryogenic Performance of an SRF Deflecting Cavity Fabricated Using Alternative Techniques for the ARIEL eLinac 4992
 
  • D.W. Storey
    Victoria University, Victoria, B.C., Canada
  • R.E. Laxdal, Z.Y. Yaopresenter
    TRIUMF, Vancouver, Canada
 
  A 650 MHz SRF deflecting mode cavity has been built and tested for use as a three-way beam separator in the ARIEL eLinac. The cavity operates in a TE-like mode, and has been optimized for high shunt impedance with minimal longitudinal footprint. The device is the first SRF cavity to be fully fabricated in house at TRIUMF. The requirements of the cavity allowed for the development of low cost manufacturing techniques, including the use of Reactor grade niobium and atmospheric pressure TIG welding. The cavity has been fabricated and tested at 4 K and 2 K, obtaining a 4 K Qo of 4·108 at the operating voltage of 0.3 MV, surpassing the goal voltage and quality factor required for operation. Results of the cryogenic tests of the cavity will be presented here.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML132  
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THPML133 Design and Optimization of the Electron Gun 4995
 
  • K. Huang, T.L. Hepresenter, Z.L. Ren, D.R. Xu, H. Xu
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  • Y. Chen
    Department of Information Engineering , Anhui Economic Management Cadres' Institute, Hefei, Anhui, People's Republic of China
 
  Funding: Work supported by the National Nature Science Foundation of China under Grant Nos.11375176 and 10875118.
Design of an energy-modified electron gun is of significance to do some research on the properties of Diamond-amplified cathode. Based on the design method of the Pierce electron gun, the optimum parameters of the electron gun have been obtained using the Opera-3D program. And the beam waist's position, the beam current, the beam size and the beam emittance related to the electron bean energy was investigated in this paper.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML133  
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THPML134 Design of the Magnets of the HALS Project 4998
 
  • Z.L. Ren, C. Chen, T.L. Hepresenter, L. Wang, X.Q. Wang, H. Xu, B. Zhang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  Funding: Work supported by the National Nature Science Foundation of China under Grant Nos.11375176 * hlxu@ustc.edu.cn ** zhbo@ustc.edu.cn
The Hefei Advanced Light Source (HALS) is a future soft X-ray diffraction-limited storage ring at NSRL, this project aims to improve the brilliance and coherence of the X-ray beams and to decrease the horizontal emittance. The lattice of the HALS ring relies on magnets with demanding specifications, including combined function dipole-quadrupoles (DQs) with high gradients, dipoles with longitudinal gradients (DLs), high gradient quadrupoles and strong sextupoles. The combined dipole-quadrupole design developed is between the offset quadrupole and septum quadrupole types. The longitudinal-gradient dipoles are permanent magnets. The quadrupoles and sextupoles rely on a more conventional design. All the magnets have been designed using POSSION, Radia, and OPERA-3D.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML134  
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THPML135 Design of the Combined Function Dipole-Quadrupoles (DQS) with High Gradients 5001
 
  • Z.L. Ren, C. Chen, T.L. Hepresenter, L. Wang, X.Q. Wang, H. Xu, B. Zhang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  Funding: Work supported by the National Nature Science Foundation of China under Grant Nos.11375176 * hlxu@ustc.edu.cn **zhbo@ustc.edu.cn
Combined dipole-quadrupoles (DQs) can be obtained with the design of tapered dipole or offset quadrupole. However, the tapered dipole design can not achieve a high gradient field, as it will lead to poor field quality in the low field area of the magnet bore, and the design of offset quadrupole will increase the magnet size and power consumption. Finally, the dipole-quadrupole design developed is between the offset quadrupole and septum quadrupole types. The dimensions of the poles and the coils of the low field side have been reduced. The 2D pole profile is simulated and optimized by using POSSION and Radia, while the 3D modle using Radia and OPERA-3D. The end shimming and chamfer are modelled to meet the field uniformity requirement.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML135  
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THPML136 Study of Secondary Electron Generation and Transport in Diamond 5004
SUSPF025   use link to see paper's listing under its alternate paper code  
 
  • T.L. He, K. Huang, Z.L. Ren, L. Wang, D.R. Xu, H. Xu
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  Energetic primary electrons (~ keV) impinging on the diamond film with its both surface under bias field in ~ MV/m, will excite secondary electron (SE) response including SE generation & transport. Although there have been 3D Monte Carlo (MC) simulation to study the two processes, this paper will introduce another method. Based on optical dielectric model, 3D MC simulation was implemented to study the generation process, and SE generation function was obtained by fitting the calculations. Using this function, the diffusion-drift equation of charge carriers (electron and hole) can be solved in 1D for the transport process, and the variation of SE depth distribution with time can be obtained.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML136  
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THPML138 Efficiency and Error Analysis of the HALS Injection Scheme 5008
 
  • Z.B. Sun, G. Liu, W. Liu, F.L. Shang, L. Shang, W.B. Song
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  Hefei Advanced Light Source (HALS) is a newly designed diffraction-limited storage ring.. The latest version of HALS has a 7BA lattice. One of the most important parts about HALS design is its injection system. Since conventional injection scheme is not suitable for DLSRs, many new injection schemes are proposed, including longitudinal injection scheme. In this paper, we investigate the feasibility of longitudinal injection scheme for HALS. In order to evaluate the injection performance, various errors have been considered. A series of tracking simulations are carried out and injection efficiency is obtained under different error levels.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML138  
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THPML140 Radiation Monitoring System of HLSII 5011
 
  • Lin, H.S. Lin, Y.Q. Cai, S.P. Jiang, Z.B. Sunpresenter, Z.R. Zhou
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  Funding: Supported by the National Science Foundation of China 11675170 By the Fundamental Research Funds for the Central Universities WK2310000056
Monitoring of ionizing radiation of synchrotron radiation facility is very important for the safety of staff and users of the light source. Radiation monitoring system of HLSII has been built and the whole system consists of local radiation monitoring spots and central control system, and a web-based monitoring dynamic release system. The local radiation monitoring spot consists of a high air pressure ionization type gamma detector and a BF3 counting tube neutron detector, and the radiation data are calculated by microcontroller locally and acquired by the data server for further processing. The dynamic release system is integrated with EPICS interface and radiation safety interlock system. Other accelerator systems could obtain radiation data from the server and the interlock system is triggered by the radiation data to shut down the machine in case the radiation exceeds the safety threshold.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML140  
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