Keyword: vacuum
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MOZGBE3 Primary Study of High-Power Graphene Beam Window Windows, proton, target, scattering 47
 
  • H. Wang, C. Meng, H. Qu, D.H. Zhu
    IHEP, Beijing, People's Republic of China
  • X. Sun, P.C. Wang
    DNSC, Dongguan, People's Republic of China
 
  Beam windows are usually used to isolate vacuum or other special environments, which is a key device for high-power accelerators. Graphene has extremely high thermal conductivity, high strength and high transparency to high energy ions. It is highly suitable for beam windows if the technology is allowable. This paper will discuss the primary tests of graphene films, including vacuum per-formance and thermal conductivity performance, as well as the simulated performance of an assumed graphene window.  
slides icon Slides MOZGBE3 [1.756 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBE3  
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MOZGBE4 Overview of Fabrication Techniques and Lessons Learned with Accelerator Vacuum Windows Windows, target, operation, site 51
 
  • C.R. Ader, M.W. McGee, L.E. Nobrega, E.A. Voirin
    Fermilab, Batavia, Illinois, USA
 
  Funding: Operated by Fermi Research Alliance, LLC, under Contract No. DE-AC02- 07CH11359 with the U.S. Department of Energy.
Vacuum thin windows have been used in Fermilab's accelerators for decades and typically have been overlooked in terms of their criticality and fragility. Vacuum windows allow beam to pass through while creating a boundary between vacuum and air or high vacuum and low vacuum areas. The design of vacuum windows, including titanium and beryllium windows, will be discussed as well as fabrication, testing, and operational concerns. Failure of windows will be reviewed as well as safety approaches to mitigating failures and extending the lifetimes of vacuum windows. Various methods of calculating the strengths of vacuum windows will be explored, including FEA.
 
slides icon Slides MOZGBE4 [2.160 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBE4  
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MOZGBE5 Results on the FCC-hh Beam Screen at the KIT Electron Storage Ring KARA photon, electron, experiment, radiation 55
 
  • L.A. Gonzalez, V. Baglin, P. Chiggiato, C. Garion, M. Gil Costa, R. Kersevan
    CERN, Geneva, Switzerland
  • I. Bellafont, F. Pérez
    ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
  • S. Casalbuoni, E. Huttel
    KIT, Eggenstein-Leopoldshafen, Germany
 
  Funding: * The European Circular Energy-Frontier Collider Study (EuroCirCol) project has received funding from the European Union's Horizon 2020 research and innovation programme under grant No 654305.
In the framework of the EuroCirCol collaboration* (work package 4 "Cryogenic Beam Vacuum System"), the fabrication of 3 FCC-hh beam-screen (BS) prototypes has been carried out with the aim of testing them at room temperature at the Karlsruhe Institute of Technology (KIT) 2.5 GeV electron storage ring KARA (KArlsruhe Research Accelerator). The 3 BS prototypes will be tested on a beamline installed by the collaboration, named as BEam Screen TEstbench EXperiment (BESTEX). KARA has been chosen because its synchrotron radiation (SR) spectrum, photon flux and power, match the one foreseen for the 50+50 TeV FCC-hh proton collider. Each of the 3 BS prototypes, 2 m in length, implement a different design feature: 1) baseline design (BD), with electro-deposited copper and no electron-cloud (EC) mitigation features; 2) BD with set of distributed cold-sprayed anti-EC clearing electrodes; 3) BD with laser-ablated anti-EC surface texturing. We present here the results obtained so far at BESTEX and the comparison with extensive montecarlo simulations of the expected outgassing behavior under synchrotron radiation.
The information herein only reflects the views of its authors and the European Commission is not responsible for any use that may be made of the information.
 
slides icon Slides MOZGBE5 [4.323 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBE5  
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MOPMF031 Modelling Wake Impedance of a Rough Surface in Application to the FCC-hh Beamscreen impedance, coupling, electron, laser 157
 
  • S. Arsenyev, D. Schulte
    CERN, Geneva, Switzerland
 
  The inner surface of the future circular collider (FCC-hh) beamscreen is proposed to be laser-treated in order to mitigate the electron cloud build-up. However, the rough structure of the treated surface can result in unwanted impedance increase, potentially leading to the transverse mode coupling instability (TMCI). Three models have been adopted to estimate the wake impedance of a beamscreen with a rough surface. The models use the resistive wall formalism generalized for the case of an arbitrary surface impedance. The results apply to a beamscreen of a circular cross-section with the homogeneously rough inner surface for the case of ultrarelativistic particles. The free parameters of the models were fit into preliminary measurements of the surface resistivity, giving, as a result, a range of the real and the imaginary parts of the wake impedance.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF031  
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MOPMF053 Observations, Analysis and Mitigation of Recurrent LHC Beam Dumps Caused by Fast Losses in Arc Half-Cell 16L2 MMI, operation, electron, solenoid 228
 
  • J.M. Jimenez, D. Amorim, S. A. Antipov, G. Arduini, A. Bertarelli, N. Biancacci, B. Bradu, E. Bravin, G. Bregliozzi, K. Brodzinski, R. Bruce, X. Buffat, L.R. Carver, P. Chiggiato, S.D. Claudet, P. Collier, R. Garcia Alia, M. Giovannozzi, L. K. Grob, E.B. Holzer, W. Höfle, G. Iadarola, G. Kotzian, A. Lechner, T.E. Levens, B. Lindstrom, T. Medvedeva, A. Milanese, D. Mirarchi, E. Métral, D. Perini, S. Redaelli, G. Rumolo, B. Salvant, R. Schmidt, M. Valette, D. Valuch, J. Wenninger, D. Wollmann, C. Yin Vallgren, C. Zamantzas, M. Zerlauth
    CERN, Geneva, Switzerland
  • D. Amorim
    Université Grenoble Alpes, Grenoble, France
  • A.A. Gorzawski
    University of Manchester, Manchester, United Kingdom
  • L. Mether
    EPFL, Lausanne, Switzerland
 
  Recurrent beam dumps significantly perturbed the operation of the CERN LHC in the summer months of 2017, especially in August. These unexpected beam dumps were triggered by fast beam losses that built up in the cryogenic beam vacuum at the half-cell 16 left of LHC-IP2 and were detected either at that location but mainly in the collimation insertions. This contribution details the experimental observables (beam losses, coherent instabilities, heat load to cryogenic system, vacuum signals), the extent of the understanding of the beam loss and instability mechanisms and the mitigation steps and new settings that allowed recovering the luminosity performance of the LHC for the rest of the Run.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF053  
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MOPMF070 High Voltage Design for the Electrostatic Septum for the Mu2e Beam Resonant Extraction cathode, high-voltage, simulation, extraction 289
 
  • M.L. Alvarez, C.C. Jensen, D.K. Morris, V.P. Nagaslaev, H. Pham, D.G. Tinsley
    Fermilab, Batavia, Illinois, USA
 
  Two electrostatic septa (ESS) are being designed for the slow extraction of 8GeV proton beam for the Mu2e experiment at Fermilab. Special attention is given to the high voltage components that affect the performance of the septa. The components under consideration are the high voltage (HV) feedthrough, cathode standoff (CS), and clearing electrode ceramic standoffs (CECS). Previous experience with similar HV systems at Fermilab was used to define the evaluation criteria of the design of the high voltage components. Using electric field simulation software, high E-field intensities on the components and integrated field strength along the surface of the dielectric material were minimized. Here we discuss the limitations found and improvements made based on those studies.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF070  
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MOPMF085 Beam-gas Background Characterization in the FCC-ee IR simulation, scattering, background, optics 322
 
  • M. Boscolo, O.R. Blanco-García
    INFN/LNF, Frascati (Roma), Italy
  • H. Burkhardt, R. Kersevan, M. Lueckhof
    CERN, Geneva, Switzerland
  • F. Collamati
    INFN-Roma1, Rome, Italy
 
  The MDISim toolkit is used to evaluate and characterize the beam-gas induced background in the FCC-ee Interaction Region. MDISim allows a full characterization of this beam background source with the locations where the beam-gas scattering occurs as well as the loss points, as a function of different vacuum conditions and composition, for the nominal optics and parameters. Detailed pressure distribution profiles have been obtained running coupled synchrotron radiation and molecular flow montecarlo codes, as an input to the GEANT4 calculations. The particles hitting the pipe in the IR can be tracked in the detectors with a full Geant-4 simulation. Semi-analytic estimates for the expected rates and lifetime are also performed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF085  
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MOPMK012 Electron Cloud Studies in FCC-ee electron, collider, simulation, quadrupole 374
 
  • E. Belli
    Sapienza University of Rome, Rome, Italy
  • P. Costa Pinto, G. Rumolo, T.F. Sinkovits, M. Taborelli
    CERN, Geneva, Switzerland
  • M. Migliorati
    INFN-Roma1, Rome, Italy
 
  Electron cloud effects are one of the most critical aspects for the LHC and the future circular colliders. In the frame of the electron-positron collider FCC-ee, an estimation of the electron cloud build up in the machine will be discussed in this paper. A preliminary evaluation of the heat load in the arc components and interaction region magnets will be presented, together with possible mitigation strategies.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK012  
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MOPML011 Liquid Cluster Ion Beam Processing of Transition Metal Films acceleration, radiation, target, experiment 415
 
  • D. Shimizu, H. Ryuto, M. Takeuchi, D. Yamamoto
    Kyoto University, Photonics and Electronics Science and Engineering Center, Kyoto, Japan
 
  The irradiation effects of cluster ion beams are characterized by the high-density collision of molecules that comprise the clusters against a target. According to molecular dynamics calculations, the local temperature of the colliding cluster and the surface of the target are expected to increase to several thousand K. The enhancement of the chemical interactions between the molecules in the colliding clusters and the atoms on the target surface is expected, if polyatomic molecules, such as ethanol and acetone, are used for the source material of the cluster. So, the irradiation effects of the polyatomic liquid cluster ion beams on transition metal films have been studied to examine the possibility of utilizing the liquid cluster ion beam technique for the processing of transition metal films. The transition metal films were formed by magnetron sputtering. The liquid clusters were produced by the adiabatic expansion method and ionized by electron ionization. The sputtering yields of transition metal films induced by liquid cluster ions are discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML011  
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MOPML029 A Portable X-ray Source Based on Dielectric Accelerators electron, target, shielding, solenoid 464
 
  • C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • S.P. Antipov, A. Kanareykin, R.A. Kostin
    Euclid Beamlabs LLC, Bolingbrook, USA
 
  Funding: The work has been supported by the U.S. Department of Homeland Security (DHS), Domestic Nuclear Detection Office (DNDO), under a competitively awarded contract No. HSHQDC-17-C-00007.
The portable low energy accelerator based X-ray sources have attractive applications in the non-destructive examination as a replacement of radiological gamma isotope sources. We are developing an inexpensive ultra-compact dielectric accelerator technology for low energy electron beams. The portability in the realm of this proposal is unprecedented ~ 1 ft3 volume with ~ 50 lbs of weight. The use of ceramics makes the transverse size of the accelerating waveguide comparable to that of a pencil. Because of this size reduction, additional weight reduction of shielding becomes possible. The article will report on the progress of this project.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML029  
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MOPML062 Accelerator Neutron Source for Boron Neutron Capture Therapy neutron, proton, experiment, tandem-accelerator 550
 
  • S.Yu. Taskaev, D.A. Kasatov, A.N. Makarov, Y.M. Ostreinov, I.M. Shchudlo, I.N. Sorokin
    BINP SB RAS, Novosibirsk, Russia
  • T.A. Bykov
    Budker INP & NSU, Novosibirsk, Russia
  • Ya.A. Kolesnikov, A.M. Koshkarev, E.O. Sokolova
    NSU, Novosibirsk, Russia
 
  Funding: This study was carried out with a grant from the Russian Science Foundation (project No. 14-32-00006-P) with the support of the Budker Institute of Nuclear Physics and Novosibirsk State University.
A source of epithermal neutrons based on a vacuum-insulated tandem accelerator and a lithium target is developed for the technique of boron neutron capture therapy. A stationary proton beam of 2 MeV with a current of up to 5 mA was obtained in the accelerator. Neutron generation was performed and the flux and neutron spectrum were experimentally measured. A Beam Shaping Assembly was developed and manufactured, which makes it possible to form a therapeutic beam of neutrons to the greatest extent satisfying the requirements of BNCT. It was established that neutron irradiation of tumor cells of human glioma U251 and human glioblastoma T98G, previously incubated in a medium with boron, led to a significant suppression of their viability. Irradiation of mice with grafted human glioblastoma tumor led to their complete cure. In order to increase the beam parameters, the facility was equipped with a wire scanner OWS-30 (D-Pace, Canada; under the license of TRIUMF), a non-contact current sensor NPTC (Bergos, France), a FLIR T650SC infrared camera, an Optris CT Laser 3ML SF pyrometer (Optris, GmbH, Germany), cooled diaphragms with thermistors, telescopic beam receivers with thermoresistors, a new bushing insulator. Two new sources of negative hydrogen ions with a high current are being prepared, one of them is surface-plasma, the other is voluminous. The investigations established the effect of space charge and spherical aberration of lens on the ion beam transport, the dependence of the heating of the diaphragms of the electrodes and the size of the proton beam on the current of the injected beam of negative hydrogen ions and the pressure of the residual gas in the transport channel. The report describes the modernization of the accelerator, discusses the results of research, declares plans.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML062  
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MOPML066 Ultrafast Mega-electron-volt Gas-Phase Electron Diffraction at SLAC National Accelerator Laboratory electron, gun, laser, experiment 556
 
  • X. Shen, R.K. Li, X.J. Wang, S.P. Weathersby, J. Yang
    SLAC, Menlo Park, California, USA
 
  Funding: This work was supported in part by the U.S. Department of Energy Contract No. DE-AC02-76SF00515, and the SLAC UED/UEM Initiative Program Development Fund.
Ultrashort mega-electron-volt (MeV) electron beams from radio-frequency (rf) photoinjectors have recently attracted strong interests for application in ultrafast gas-phase electron diffraction (UGED). Such high-brightness electron beams are capable of providing 100-fs level temporal resolution and sub-Angstrom level spatial resolution to capture the ultrafast structural dynamics from photoexcited gas molecules. To experimentally demonstrate such an ultrafast electron scattering instrument, a high performance UGED system has been commissioned at SLAC National Accelerator Laboratory. The UGED instrument produces 3.7 MeV electron beams with 2 fC beam charge at 180-Hz repetition rate. The temporal resolution is characterized to be 150 fs full-width-at-half-maximum (FWHM), while the spatial resolution is measured to be 0.76 Å FWHM. The UGED instrument also demonstrates outstanding performance in vacuum, rf, and electron beam pointing stability. Details of the performance of the SLAC MeV UGED system is reported in this paper.
 
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TUYGBD2 A Review of DAΦNE Performances During the KLOE-2 Run luminosity, detector, operation, collider 624
 
  • C. Milardi, D. Alesini, S. Bini, O.R. Blanco-García, M. Boscolo, B. Buonomo, S. Cantarella, S. Caschera, A. D'Uffizi, A. De Santis, G.O. Delle Monache, D.G.C. Di Giulio, G. Di Pirro, A. Drago, L.G. Foggetta, A. Gallo, R. Gargana, A. Ghigo, S. Guiducci, C. Ligi, M. Maestri, A. Michelotti, L. Pellegrino, R. Ricci, U. Rotundo, A. Stecchi, A. Stella, M. Zobov
    INFN/LNF, Frascati (Roma), Italy
 
  DAΦNE, the Frascati electron-positron accelerator complex, has almost completed the last and more chanlleging period of operation for the KLOE-2 detector. In this context the performances of the collider, based on the Crab-Waist collision scheme, are reviewed and the limiting factors discussed.  
slides icon Slides TUYGBD2 [9.932 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUYGBD2  
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TUPAF012 Commissioning of the Lipac Medium Energy Beam Transport Line cavity, rfq, controls, operation 683
 
  • I. Podadera, J. Castellanos, J.M. García, D. Gavela, A. Ibarra, D. Jiménez-Rey, A. Marqueta, L.M. Martinez Fresno, E. Molina Marinas, J. Mollá, P. Méndez, C. Oliver, D. Regidor, F. Toral, R. Varela, V. Villamayor, M. Weber, C. de la Morena
    CIEMAT, Madrid, Spain
  • P. Cara, A. Marqueta, I. Moya
    Fusion for Energy, Garching, Germany
  • T. Ebisawa, Y. Hirata, A. Ihara, Y. Ikeda, A. Kasugai, T. Kitano, K. Kondo, T. Narita, K. Sakamoto, T. Shinya, M. Sugimoto
    QST, Aomori, Japan
  • D. Gex, A. Jokinen
    F4E, Germany
  • J. Knaster
    IFMIF/EVEDA, Rokkasho, Japan
  • M. Mendez Macias
    7S, Peligros (Granada), Spain
  • O. Nomen
    IREC, Sant Adria del Besos, Spain
  • G. Pruneri
    Consorzio RFX, Associazione Euratom-ENEA sulla Fusione, Padova, Italy
  • F. Scantamburlo
    INFN/LNL, Legnaro (PD), Italy
 
  Funding: This work has been funded by the Spanish Ministry of Economy and Competitiveness under the Agreement as published in BOE, 16/01/2013, page 1988 and the project FIS2013-40860-R.
LIPAc* will be a 9 MeV, 125 mA CW deuteron accelerator which aims to validate the technology to be used as neutron source of the IFMIF facility. Those facilities are essential for future fusion reactors material research. A 175 MHz RFQ will increase the energy up to 5 MeV before a Superconducting RF (SRF) linac with eight 175 MHz Half Wave Resonators brings the particles up to the final energy of 9 MeV. Between both stages, a Medium Energy Beam Transport line (MEBT)** aims at transporting and matching the beam between the RFQ and the SRF linac. The transverse focusing of the beam is controlled by five quadrupole magnets with integrated steerers, grouped in one triplet and one doublet. Two buncher cavities handle the longitudinal dynamics. Two movable scraper systems are included to purify the beam optics coming out the RFQ and avoid losses in the SRF linac. In this contribution, checkout of the beamline and its ancillaries in Japan is reported. Tests carried out on the beamline prior to the MEBT beam commissioning are described, focusing in vacuum tests, magnets powering, buncher conditioning and scrapers movement.
* P. Cara et al., IPAC16, MOPOY057 , p.985, Busan, Korea (2016)
** I. Podadera et al., LINAC2016, TUPLR041, p.554, East Lansing, USA (2016).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF012  
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TUPAF015 Preliminary Test Results of the First ESS Elliptical Cryomodule Demonstrator cavity, cryomodule, cryogenics, radiation 691
 
  • F. Peauger, C. Arcambal, S. Berry, P. Bosland, E. Cenni, G. Devanz, T. Hamelin, O. Piquet, B. Renard, P. Sahuquet, T. Trublet
    CEA/DRF/IRFU, Gif-sur-Yvette, France
  • C. Darve
    ESS, Lund, Sweden
  • P. Michelato
    INFN/LASA, Segrate (MI), Italy
  • G. Olivier
    IPN, Orsay, France
  • J.P. Thermeau
    Laboratoire APC, Paris, France
 
  Two ESS elliptical cavities cryomodule prototypes are being developed and will be tested at CEA Saclay before starting the series production. This paper presents the preliminary test results of the first medium beta cavities cryomodule demonstrator M-ECCTD. The measurements of the cryogenic performances at 80 K and 2 K of the different cryomodule components and circuits are given. The first RF test results performed at low power are also reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF015  
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TUPAF021 Identification and Removal of SPS Aperture Limitations optics, target, proton, injection 709
 
  • V. Kain, R. Alemany-Fernández, H. Bartosik, S. Cettour Cave, K. Cornelis, P. Cruikshank, J.A. Ferreira Somoza, B. Goddard, C. Pasquino
    CERN, Geneva, Switzerland
 
  The CERN SPS (Super Proton Synchrotron) serves as LHC injector and provides beam for the North Area fixed target experiments. Since the 2016 run automated local aperture scans have been performed with the main focus on the vertical plane where limitations typically arise due to the flat vacuum chambers in most SPS elements. For LHC beams the aperture limitations with the present low integer tune optics also occur at locations with large dispersion. Aperture measurements in the horizontal plane using a variety of techniques were performed and showed surprising results, which could partially explain the unexpected losses of high intensity LHC beams at the SPS flat bottom. In this paper, reference measurements from 2016 are compared with the ones taken at the beginning of the run in 2017. Several aperture restrictions in the vertical plane could be found and cured, and a potential systematic restriction in the horizontal plane has been identified. The results of the measurements and the origin of the restrictions are presented in this paper, and the outlook for partial mitigation is discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF021  
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TUPAF030 Electron Cloud Build Up for LHC Sawtooth Vacuum Chamber electron, photon, simulation, synchrotron 744
 
  • G. Guillermo Cantón, F. Zimmermann
    CERN, Geneva, Switzerland
  • G.H.I. Maury Cuna, E. D. Ocampo
    Universidad de Guanajuato, División de Ciencias e Ingenierías, León, Mexico
 
  At high proton-beam energies, beam-induced synchrotron radiation is an important source of heating, of beam-related vacuum pressure increase, and of primary photoelectrons, which can give rise to an electron cloud. For the arcs of LHC a sawtooth pattern had been imprinted on the horizontally outward side  of the vacuum chamber in order to locally absorb synchrotron radiation photons without dispersing them all around the chamber. Using the combination of the codes Synrad3D and PyCLOUD we examine the effect of realistic absorption distributions with and without sawtooth on the build up of electron clouds.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF030  
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TUPAF037 Validation of the CERN PS Eddy Current Injection Septa septum, simulation, injection, HOM 768
 
  • M. Hourican, B. Balhan, J.C.C.M. Borburgh, T. Masson, A. Sanz Ull
    CERN, Geneva, Switzerland
 
  As part of the upgrade of the CERN PS accelerator from 1.4 GeV to 2 GeV, new injection septa have been developed. The system is comprised of a pulsed eddy current septum magnet and a pulsed eddy current bumper magnet. Both magnets will be housed in a common vacuum vessel and powered by independent power converters. In-depth studies and simulations have been performed to reduce as much as possible the leak field by designing specific magnetic shielding, combined with dual function beam impedance shielding. A prototype magnet was built and measured to validate the simulations. The final complete system will be bake-able at 200C and uses demineralised water for cooling. Closed circuit cooling systems have been integrated to reduce risks of vacuum leaks. This report describes the electromechanical design from the concept and simulation stages to the prototyping and final manufacturing. Results of the initial magnetic measurements, including field homogeneity and leak field mitigation methods are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF037  
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TUPAF049 Analysis of Loss Signatures of Unidentified Falling Objects in the LHC proton, operation, beam-losses, electron 814
 
  • L. K. Grob, M. Dziadosz, E.B. Holzer, A. Lechner, B. Lindstrom, R. Schmidt, D. Wollmann, C. Zamantzas
    CERN, Geneva, Switzerland
 
  Particulates in the LHC beam pipes can interact with the proton beams and cause significant beam losses. The "UFOs" (unidentified falling objects) hypothesis describes a particle falling into the beam, creating particle showers, being ionized and repelled. Though the signals of the beam loss monitors support this, many aspects remain unknown. Neither the source of the dust nor the release mechanism from the beam pipe are understood. The same holds for the forces involved in the interaction and the observed UFO rate reduction over the years. These open questions are approached from different angles. Firstly, a new data analysis tool was established featuring advanced raw data selection and statistical analysis. Results of this analysis will be presented. Secondly, dust samples were extracted from LHC components and analyzed to gain insight into the size distribution and material composition of the contamination. The performed observations and analysis lead to a better modelling of the UFO events and helped to understand the physics involved. The validated UFO models will be crucial in view of the high luminosity upgrade of the LHC (HL-LHC) and the Future Circular Collider (FCC).  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF049  
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TUPAF057 The SPS Tests of the HL-LHC Crab Cavities cavity, cryomodule, HOM, operation 846
 
  • R. Calaga, O. Capatina, G. Vandoni
    CERN, Geneva, Switzerland
 
  Funding: Research supported by the HL-LHC project
Two superconducting crab cavities in the framework of the High Luminosity (HL-LHC) LHC were built to test for the first time with proton beams in the Super Proton Synchrotron (SPS) at CERN. These tests will address the operation of the crab cavities in a high current and high intensity proton machine through the full energy cycle with a primary focus on cavity transparency, performance and stability, failures modes and long term effects on proton beams. An overview of the SPS cryomodule development towards the SPS tests along with the first test results are presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF057  
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TUPAF068 Functional Integration of the RFQ in the ESS Systems rfq, cavity, controls, LLRF 890
 
  • J.S. Schmidt, E. Bargalló, T. Fay, G. Hulla, B. Lagoguez, R. Montaño, E. Sargsyan, S. Scolari, H. Spoelstra
    ESS, Lund, Sweden
  • A.C. Chauveau, M. Desmons, O. Piquet
    CEA/IRFU, Gif-sur-Yvette, France
  • A.J. Johansson
    Lund University, Lund, Sweden
  • W. Ledda
    Vitrociset s.p.a, Roma, Italy
 
  The 352 MHz Radio Frequency Quadrupole (RFQ) for the European Spallation Source ERIC (ESS) will be delivered during 2018. After delivery, installation and tuning of the cavity, the high power RF conditioning will be performed. At this point all the different systems that are needed to condition and operate the RFQ have to be in place and operational. This paper will give an overview of the system analysis that has been performed for the RFQ. The RFQ requirements for the RF system, including the RF distribution system (RFDS), the Low Level RF (LLRF) and the local RF protection system (RFLPS) will be presented. In addition, the paper covers the system integration of the structure in the ESS control and vacuum systems as well as the outcome of a machine protection analysis.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF068  
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TUPAF076 Design of PIP-II Medium Energy Beam Transport SRF, linac, kicker, cryomodule 905
 
  • A. Saini, C.M. Baffes, A.Z. Chen, V.A. Lebedev, L.R. Prost, A.V. Shemyakin
    Fermilab, Batavia, Illinois, USA
 
  Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics
The Proton Improvement Plan-II (PIP-II) is a proposed upgrade for the accelerator complex at Fermilab. The central piece of PIP-II is a superconducting radio frequency (SRF) 800 MeV linac capable of operating in both CW and pulse regimes. The PIP-II linac comprises a warm front-end that includes a H ion source capable of delivering 15-mA, 30-keV DC or pulsed beam, a Low Energy Beam Transport (LEBT), a 162.5 MHz, CW Radio-Frequency Quadrupole (RFQ) accelerating the ions to 2.1 MeV and, a 14-m Medium Energy Beam Transport (MEBT) before beam is injected into SRF part of the linac. This paper presents the PIP-II MEBT design and, discusses operational features and considerations that lead to existing optics design such as bunch by bunch chopping system, minimization of radiation coming to the warm front-end from the SRF linac using a concrete wall, a robust vacuum protection system etc.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF076  
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TUPAF084 The First-of-Series SIS100 Cryocatcher cryogenics, site, HOM, instrumentation 930
 
  • L.H.J. Bozyk, Sh. Ahmed, P.J. Spiller
    GSI, Darmstadt, Germany
 
  The superconducting heavy ion synchrotron SIS100 of the FAIR-facility will be equipped with 60 cryocatcher, to suppress dynamic vacuum effects. A prototype cryocatcher has been designed, manufactured and underwent several tests. The results yielded in the design of the series cryocatcher. Recently, the First-of-Series cryocatcher has been manufactured and tested. Results from the manufacturing process and the site acceptance tests, including cryogenic test with liquid helium are presented. The FoS cryocatcher sucessfully passed all tests and the series production will be released.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF084  
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TUPAK012 Conceptual Design of a Single-Ended MA Cavity for J-PARC RCS Upgrade cavity, acceleration, operation, power-supply 987
 
  • M. Yamamoto, M. Nomura, T. Shimada, F. Tamura
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • M. Furusawa, K. Hara, K. Hasegawa, C. Ohmori, Y. Sugiyama, M. Yoshii
    KEK, Tokai, Ibaraki, Japan
 
  The J-PARC RCS employes Magnetic Alloy (MA) loaded cavities and rf power is fed by vacuum tubes in push-pull operation. The multi-harmonic rf driving and the multi-harmonic beam loading compensation are realized due to the broadband characteristics of the MA. However, the push-pull operation has disadvantages in the multi-harmonics. An unbalance of the anode voltage swing remarkably appears at very high intensity beam acceleration. In order to avoid the unbalance, a single-ended MA cavity is considered for the RCS beam power upgrade because no unbalance arises intrinsically. We will describe the conceptual design of the single-end MA cavity for the RCS upgrade.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAK012  
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TUPAL046 Construction, Test, and Operation of a new RFQ at the Spallation Neutron Source (SNS) rfq, operation, linac, ion-source 1113
 
  • Y.W. Kang, A.V. Aleksandrov, W.E. Barnett, M.S. Champion, M.T. Crofford, B. Han, S.W. Lee, J. Moss, R.T. Roseberry, J.P. Schubert, A.P. Shishlo, M.P. Stockli, C.M. Stone, R.F. Welton, D.C. Williams, A.P. Zhukov
    ORNL, Oak Ridge, Tennessee, USA
  • C.C. Peters, J. Price
    ORNL RAD, Oak Ridge, Tennessee, USA
 
  Funding: * This work was supported by SNS through UT-Battelle, LLC, under contract DEAC0500OR22725 for the U.S. DOE.
A new RFQ was successfully installed recently in the SNS linac to replace the old RFQ that was used for more than a decade with certain operational limitations. The new RFQ was completely tested with H ion source in the Beam Test Facility (BTF) at SNS. For robust operation of SNS at 1.4 MW, the full design beam power and to satisfy the beam current requirement of the forthcoming SNS proton power upgrade (PPU) project, an RFQ with enhanced performance and reliability was needed. The new RFQ was built to have the beam parameters identical to those of the first RFQ but with improved RF and mechanical stability and reliability for continuous operation of neutron production. The tests confirmed that the new RFQ can run with high beam transmission efficiency at around 90 % and notably improved operational stability. In this paper, construction, test, installation, and operation of the new RFQ in SNS are discussed with the performance improvements.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL046  
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TUPAL055 Progress with Carbon Stripping Foils at ISIS operation, synchrotron, injection, proton 1136
 
  • B. Jones, H.V. Cavanagh
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
 
  The ISIS Facility at the Rutherford Appleton Laboratory produces intense neutron and muon beams for condensed matter research. The facility's 50Hz rapid cycling synchrotron accelerates protons from 70 to 800MeV to deliver a mean beam power of 0.2MW to two target stations. Since 2016, ISIS has routinely used commercially produced carbon based foils for beam stripping during charge-exchange injection. Recent experience and developments to increase useful foil lifetime are presented including in-house high temperature annealing of foils prior to use. The installation and performance of a new foil imaging system are described and, finally, the procedure to change the stripping foil is described. Issues with the current arrangements and options for redesign are discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL055  
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TUPAL056 High Order Image Terms and Harmonic Closed Orbits at the ISIS Synchrotron closed-orbit, simulation, resonance, space-charge 1140
 
  • B.G. Pine, C.M. Warsop
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
 
  ISIS is the spallation neutron source at Rutherford Appleton Laboratory in the UK. Protons are accelerated from 70 to 800 MeV in a 50 Hz rapid cycling synchrotron. Due to the intense beam, space charge forces are high during the first part of the acceleration cycle. The vacuum vessel in the synchrotron has a rectangular shape where the apertures are conformal to the design beam envelopes. At high intensities image forces interact with the beam, especially when the closed orbit is large. An analysis of image forces has been made and used to classify higher order image terms. These have been identified using simulations of round beams in rectangular vacuum vessels. The higher order image terms from harmonic closed orbits have been used with single particle resonance theory, taking account of the coherent nature of the beam response. Several predictions of beam resonance have been made. A simulation study has been carried out using a smooth focusing lattice and uniform density beams. Resonant beam behaviour has been observed and explained by the proposed theory.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL056  
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TUZGBE3 Towards Implementation of Laser Engineered Surface Structures for Electron Cloud Mitigation electron, laser, operation, multipactoring 1220
 
  • M. Sitko, V. Baglin, S. Calatroni, P. Chiggiato, B. Di Girolamo, E. Garcia-Tabares Valdivieso, M. Taborelli
    CERN, Geneva, Switzerland
  • A. Abdolvand, D. Bajek, S. Wackerow
    University of Dundee, Nethergate, Dundee, Scotland, United Kingdom
  • M. Colling, T.J. Jones, P.A. McIntosh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
 
  The LHC operation has proven that the electron cloud could be a significant limiting factor in machine performance, in particular for future High Luminosity LHC (HL-LHC) beams. Electron clouds, generated by electron multipacting in the beam pipes, leads to beam instabilities and beam-induced heat load in cryogenic systems. Laser Engineered Surface Structures (LESS) is a novel surface treatment which changes the morphology of the internal surfaces of vacuum chambers. The surface modification results in a reduced secondary electron yield (SEY) and, consequently, in the eradication of the electron multipacting. Low SEY values of the treated surfaces and flexibility in choosing the laser parameters make LESS a promising treatment for future accelerators. LESS can be applied both in new and existing accelerators owing to the possibility of automated in-situ treatment. This approach has been developed and optimised for the LHC beam screens in which the electron cloud has to be mitigated before the HL-LHC upgrade. We will present the latest steps towards the implementation of LESS.  
slides icon Slides TUZGBE3 [1.830 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUZGBE3  
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TUPMF007 Cryogenic Testing and Initial Performance of a Helical Superconducting Undulator at the APS undulator, cryogenics, operation, radiation 1260
 
  • J.D. Fuerst, E. Gluskin, Q.B. Hasse, Y. Ivanyushenkov, M. Kasa, I. Kesgin, Y. Shiroyanagi
    ANL, Argonne, Illinois, USA
 
  Funding: Work supported by the U.S. Department of Energy, Office of Science under Contract No. DE-AC02-06CH11357.
A helical superconducting undulator (HSCU) has been installed and is presently operational at the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). We describe the final assembly and cryogenic test program which led to successful operation, representing the culmination of a two-year development effort. Details of the cryostat and cryogenic system design are presented along with as-installed performance data and a comparison with design expectations.
 
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TUPMF027 Impedance Modeling for eRHIC impedance, dipole, quadrupole, electron 1309
 
  • A. Blednykh, G. Bassi, M. Blaskiewicz, C. Hetzel, V. Ptitsyn, V.V. Smaluk, F.J. Willeke
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by the US DOE under contract number DE-SC0012704
The impedance budget for the eRHIC project is discussed at its earlier stage of development. As a first step, with the eRHIC lattice and beam parameters , we use the geometric impedances of the vacuum chamber components simulated for the NSLS-II project. The impedance budged will be updated next with more impedance data simulated for the optimized eRHIC vacuum components. It will allows us to keep track on the collective effects changes with more realistic components added to the ring.
 
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TUPMF032 RF Conceptual Design of Normal Conducting Cavity for an eRHIC Rapid Cycling Synchrotron cavity, electron, GUI, coupling 1316
 
  • B. P. Xiao, M. Blaskiewicz, J.M. Brennan, D. Holmes, K.S. Smith, T. Xin, A. Zaltsman
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE.
The Rapid Cycling Synchrotron (RCS) for the eRHIC Ring-Ring design will provide on energy injection (up to 18 GeV) of high charge, polarized electron bunches to the eRHIC electron storage ring. The RF system comprises a large number of 563MHz fundamental cavities, providing up to 45MV per turn. The cavities will operate in pulsed mode with <20% duty factor, at a repetition rate of 1 Hz. In this paper we report the conceptual RF design of the cavity.
 
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TUPMF040 Alignment of Current Strips at the Canadian Light Source alignment, closed-orbit, undulator, electron 1342
 
  • W.A. Wurtz
    CLS, Saskatoon, Saskatchewan, Canada
  • Q.L. Zhang
    SINAP, Shanghai, People's Republic of China
 
  The Quantum Materials Spectroscopy Centre beamline at the Canadian Light Source will employ a 180 mm period elliptically polarizing undulator (EPU180), which will have significant impacts on beam dynamics with large tune shifts and reductions in dynamic aperture. Current strips mounted to the vacuum chamber are intended to mitigate the effects of EPU180 with each strip powered by an independent power supply. It is important to accurately model the current strips in order to calculate the required compensation. We model the current strips as straight wires, parallel to the electron beam, with small horizontal and vertical displacements from their nominal positions. As the real current strips are not completely straight, this is an effective model, but justified as we are mostly interested in the magnetic field integrated along the strips. By activating two strips and measuring the ratio of the two currents needed to minimize closed orbit distortion in the horizontal and vertical planes, we can find the effective horizontal and vertical displacements of the straight wires in the model. Our goal is to create an effective model of the strips from beam-based measurements.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF040  
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TUPMK002 First Tests of the Apple II Undulator for the LOREA Insertion Device and Front End undulator, simulation, optics, insertion-device 1488
 
  • J. Campmany, L.G.O. Garcia-Orta, J. Marcos, Z. Martí, V. Massana, M. Quispe
    ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
 
  ALBA synchrotron is currently installing the new beamline LOREA (Low-Energy Ultra-High-Resolution Angular Photoemission for Complex Materials at ALBA). It operates in the range of 10 - 1500 eV with polarized light. To produce the light for the beamline, an Apple II undulator with a period of 125 mm has been chosen. It can operate as an undulator at low energies and as a wiggler at high energies, providing a wide energy range. The device was built by KYMA, delivered on February 2017 and installed in August 2017. We present the magnetic measurements made during SAT as well as the simulations of the influence of the ID in the electron beam dynamics and the first measurements with beam. On the other hand, the high demanding characteristics of the beamline lead to a device providing high power and wide beam in some working modes. This situation has been a challenge for the Front End (FE) thermal load. It has been built by the companies RMP and TVP, and the FE modules have been installed in the tunnel along autumn 2017. We present the Site Acceptance Tests results as well as the technical solutions adopted, especially in terms of mechanical design and used materials.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMK002  
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TUPMK010 Differences in Current Dependent Tune Shifts Measured by Direct or ORM Based Methods storage-ring, impedance, optics, wakefield 1510
 
  • Y.E. Tan, R.T. Dowd
    AS - ANSTO, Clayton, Australia
 
  The change in the tunes as a function of total beam current is a well documented effect and has been attributed to quadrupole like self induced wakefields. Theoretical models presented by others have utilised direct methods (spectrum analyser) to measure the tunes in the analysis. In this report we shall present observations that show the ORM method, Linear Optics from Closed Optics (LOCO), and direct methods have significantly different tune gradients. The different tune gradients is attributed to the static (ORM) and dynamic (direct) nature of the measurements where in the static case the vacuum chamber is to be considered as a thin wall while in the dynamic case the vacuum chamber wall is to be considered as a thick wall.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMK010  
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TUPML019 Design of Multi-Alkali Photocathode Preparation System for CTFEL Facility cathode, FEL, laser, electron 1571
 
  • D.X. Xiao, M. Li, Q. Pan, H. Wang, X. Yang
    CAEP/IAE, Mianyang, Sichuan, People's Republic of China
 
  The first saturated lasing of the China Academy of Engineering Physics tera-hertz free electron laser (CTFEL) facility has been realized. In order to improve the performance of the CTFEL facility, the multi-alkali photocathode with much longer life-time has been proposed to replace the GaAs photocathode currently used. This paper presents the design of the multi-alkali photocathode preparation system, which consists of three chambers: the suitcase chamber, the preparation chamber, and the loading chamber. The function of each chamber is also discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML019  
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TUPML025 Long Lifetime Spin-Polarized GaAs Photocathode Activated by Cs2Te cathode, electron, polarization, photon 1589
 
  • J. Bae, L. Cultrera, P. Digiacomo
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • I.V. Bazarov
    Cornell University, Ithaca, New York, USA
 
  Funding: This work was supported by the Department of Energy Grant Nos. DE-SC0016203 and NSF PHY-1461111.
High intensity and highly spin-polarized electron source is of great interest to the next generation Electron Ion Colliders. GaAs prepared by the standard activation method, which is the most widely used spin-polarized photocathode, is notorious for its vacuum sensitivity and short operational lifetime. To improve the lifetime of GaAs photocathodes, we activated GaAs by Cs2Te, a material well known for its robustness. We confirmed the Cs2Te layer forms negative electron affinity on GaAs with a factor of 5 improvement in lifetime. Furthermore, the new activation method had no adverse effect on spin-polarization. Considering Cs2Te forms much thicker activation layer (~ 2 nm) compared to the standard activation layer (~ monolayer), our results trigger a paradigm shift on new activation methods with other robust materials that were avoided for their thickness.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML025  
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TUPML073 Ion Source and Low Energy Beam Transport Line Final Commissioning Step and Transfer from INFN to ESS MMI, proton, ion-source, controls 1712
 
  • L. Celona, A. Amato, G. Calabrese, A.C. Caruso, G. Castro, F. Chines, S. Gammino, O. Leonardi, A. Longhitano, G. Manno, S. Marletta, D. Mascali, A. Maugeri, M. Mazzaglia, A. Miraglia, L. Neri, S. Passarello, A. Seminara, D. Siliato, A. Spartà, G. Torrisi
    INFN/LNS, Catania, Italy
 
  At the Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud (INFN-LNS), the beam commissioning of the high intensity Proton Source for the European Spallation Source (PS-ESS) was completed in November 2017. All requirements have been satisfied and certified by the European Spallation Source (ESS). In the last step of the commissioning a complete characterization of the source has been carried out and some results are hereinafter reported. The shipment of the source was done in December 2017, followed by the installation in January while the beam commissioning is foreseen during summer 2018. The paper describes the final commissioning steps at INFN-LNS, the procedure adopted for a safe transfer of the equipment, the transfer of knowledge needed for the operation and the maintenance.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML073  
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TUPML075 Development of Target/ion Source for Li-8 Beam at KOMAC* target, ion-source, proton, operation 1718
 
  • J.J. Dang, Y.-S. Cho, H.S. Kim, H.-J. Kwon, P. Lee, S. Lee, Y.G. Song
    Korea Atomic Energy Research Institute (KAERI), Gyeongbuk, Republic of Korea
 
  Funding: This work has been supported through KOMAC operation fund of KAERI by MSIT and the NRF of Korea grant funded by the Korea government (MSIT) (No. NRF-2017M2A2A6A02071070).
A target/ion source (TIS) for Li-8 isotope beam has been developed at Korea Multi-purpose Accelerator Complex (KOMAC). The TIS was designed based on various numerical studies such as Monte Carlo simulation for Li-8 yield estimation, an ionization efficiency calculation of a surface ionization ion source and thermal analysis by a power balance model. Then, it was fabricated that a prototype of the TIS which consists of a beryllium oxide (BeO) target, a graphite target container, a tantalum target heater and a rhenium surface ion source. Also, the target heater and the surface ion source were heated to designed operation temperatures. In addition, it has been designed and constructed that an online test facility including Li-8 beam optics and diagnostics.
 
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WEXGBD1 Development of Very Short Period Undulators undulator, electron, radiation, factory 1735
 
  • S. Yamamoto
    KEK, Ibaraki, Japan
 
  Scientists and engineers at KEK have developed undulator magnets having very short period lengths. Magnet plates 100mm and 152mm long with 4-mm period length have been successfully fabricated. They produce an undulator field of approximately 4kG at a gap of 1.6mm. The magnetic field characterization shows that the undulator field is satisfactory in quality for a very short period undulator. KEK has recently installed a short-period undulator at a 50-MeV linac and observed a first light, and will soon start an experiment using a short-period undulator with laser-accelerated electrons for future table-top XFELs. This invited talk summarizes the current status, and experimental activities and results related to short-period undulators and table-top FELs.  
slides icon Slides WEXGBD1 [3.520 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEXGBD1  
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WEPAF010 Fast Glitch Detection of Coupled Bunch Instabilities and Orbit Motions feedback, storage-ring, injection, operation 1829
 
  • W.X. Cheng, B. Bacha, K. Ha, Y. Li
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by DOE contract No: DE-SC0012704
During high current operation at NSLS-II storage ring, vertical beam size spikes have been noticed. The spikes are believed due to ion instability associates with vacuum activities localized in the ring. A new tool has been developed using gated BPM turn-by-turn (TBT) data to detect beam centroid glitches. When one turn orbit deviates outside the predefined window, a global event will be generated. This allows synchronized data acquisition of TBT beam positions around the ring. Bunch by bunch data is acquired at the same time to analyze the possible coupled bunch instabilities (CBI). Besides CBI mainly due to ion bursts, fast orbit glitches have been captured with the new tool. Sources of the glitches can be identified.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF010  
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WEPAF011 Developments of Bunch by Bunch Feedback System at NSLS-II Storage Ring feedback, operation, emittance, storage-ring 1833
 
  • W.X. Cheng, B. Bacha, Y. Li
    BNL, Upton, Long Island, New York, USA
  • D. Teytelman
    Dimtel, San Jose, USA
 
  Funding: Work supported by DOE contract No: DE-SC0012704
Transverse bunch-by-bunch (BxB) feedback system has been constructed and in operation since the very beginning of NSLS-II storage ring commissioning. As the total beam current continues increasing in the past years, the system has been operating stable and reliable. Advanced BxB diagnostic functions have been developed using the system. Continuous tune measurement is realized with a diagnostic single bunch. Coupled bunch instability growth rate is able to be measured with the transient excitation. The BxB feedback system is also capable to excite a small fraction of total bunches for lattice measurement during high current operations. We present the most recent developments and operation experience on the BxB feedback system at NSLS-II.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF011  
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WEPAF012 Improvements of NSLS-II X-ray Diagnostic Beamlines emittance, storage-ring, photon, radiation 1837
 
  • W.X. Cheng, B. Bacha, B.N. Kosciuk, D. Padrazo Jr
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by DOE contract No: DE-SC0012704
There are two X-ray diagnostic beamlines (XDB) developed at NSLS-II storage ring to measure emittance, energy spread, and other machine parameters. The first beamline utilizes a soft bending magnet radiation has been in operation since 2014. The tungsten pinhole originally located in the air had corrosion issue. The beamline has been improved by extending the vacuum to the imaging system. The second X-ray pinhole beamline using three-pole wiggler (TPW) radiation has been constructed and commissioned recently. Energy spread is able to be precisely measured due to large dispersion at the source point. A gated camera is equipped with the new beamline to acquire profiles within one turn. Recent operation experience and beam measurements will be presented in this paper.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF012  
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WEPAF049 Energy Beam Position Monitor Button Array Electronics for the European XFEL electron, FEL, electronics, pick-up 1927
 
  • B. Lorbeer, B. Beutner, H.T. Duhme, L. Fröhlich, D. Lipka, D. Nölle
    DESY, Hamburg, Germany
 
  The European XFEL(X-Ray Free Electron Laser) at DESY(Deutsches Elektronen-Synchrotron) in Hamburg/Schenefeld started commissioning in early 2017. Before the pulsed electron beam is accelerated to its final energy of 14 GeV, the energy of the bunch can be compressed in three bunch compression chicanes at 130 MeV, 700 MeV and 2400 MeV. The vacuum chamber in these sections is tapered from 40 mm round beam pipe to a 40 cm rectangular shaped vacuum section. A custom made button array type of BPM(Beam position Monitor) is installed in this section with 26 button electrode feed-throughs. The analog and digital readout electronics for this monitor and the first experience with the calibration and operational aspects of this system are presented in this poster.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF049  
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WEPAF068 Frequency Scanning Interferometry as New Solution for on-Line Monitoring Inside a Cryostat for the HL-LHC project cavity, target, monitoring, dipole 1986
 
  • H. Mainaud Durand, T. Dijoud, J. Gayde, F. Micolon, M. Sosin
    CERN, Geneva, Switzerland
  • M. Duquenne, V. Rude
    ESGT-CNAM, Le Mans, France
 
  Funding: Research supported by the HL-LHC project
For the HL-LHC project, the cryostats of the key components will be equipped permanently with an on-line position monitoring system based on Frequency Scanning Interferometry (FSI). Such a system, based on absolute distance measurement, will determine the position of the inner triplet cold masses w.r.t. their cryostat and the position of the crab cavities also inside their cryostat, within an uncertainty of measurement of 0.1 mm, in a harsh environment: cold temperature of 2 K and high radiation level of the order of 1 MGy. The FSI system was validated first successfully on one LHC dipole cryostat and its associated cold mass to undergo qualification tests under different conditions: warm, vacuum and cold (2K). The FSI system also equips the first crab cavities prototype cryostat. The configuration of the FIS system chosen after simulations, the conditions of tests as well as their results and analysis are presented in this paper.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF068  
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WEPAL014 Non-Distructive 2-D Beam Profile Monitor Using Gas Sheet in J-PARC LINAC linac, injection, electron, cavity 2177
 
  • J. Kamiya, Y. Hikichi, M. Kinsho, A. Miura, N. Ogiwara
    JAEA/J-PARC, Tokai-mura, Japan
 
  We have been developed a beam profile monitor using interaction between the beam and the gas molecules distributed in sheet shape*. Generated luminescence or ions by passing the beam through the gas sheet has the information of cross-section shape of the beam. The gas sheet beam monitor will become a useful tool to measure the profile of high power beams because it has no breakable element such as wires and a 2-D beam profile at a certain position of beam line can be immediately obtained by just injecting the gas. Previously, the development of the gas sheet generator and successful demonstration of the beam profile measurement were reported. This time, we applied a gas sheet monitor to J-PARC LINAC, where the negative hydrogen atoms (H) are accelerated to the energy of 400 MeV in the normal operation. Most challenging factor was the development of the gas sheet monitor system, which generates the enough dense gas sheet to detect the clear image of the beam profile without harmful effect on the ultra-high vacuum in the beam line. We will report the gas sheet beam monitor system for J-PARC LINAC and the results of the first measurement of the beam profile.
* N. Ogiwara, et al., Proceedings of IPAC2016, p.2102.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL014  
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WEPAL058 Beam Loss Studies at the Taiwan Photon Source radiation, injection, scattering, undulator 2309
 
  • C.H. Huang, J. Chen, Y.-S. Cheng, K.T. Hsu, K.H. Hu, D. Lee, C.Y. Wu
    NSRRC, Hsinchu, Taiwan
 
  PIN-photodiodes and RadFETs are installed in the storage ring of the Taiwan Photon Source (TPS) to study beam loss distributions and mechanisms. In the highest dose area, the radiation comes mainly from hard X-rays produced by synchrotron bending magnets. During beam cleaning and after replacing a vacuum chamber, losses due to inelastic Coulomb scattering occur mostly downstream from bending magnets while elastic scattering causes electrons to get lost mainly after an elliptically polarizing undulator which has a limited vertical aperture. During the injection period, the beam loss pattern can be changed by modifying injection conditions or lattice settings. The beam loss usually happens in the injection section and small-aperture section. The injection efficiency can be improved by minimizing the detected injection loss.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL058  
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WEPMF004 The Saclay Test Stand for Conditioning the ESS RFQ Power Couplers at High RF Power cavity, rfq, linac, interface 2375
 
  • N. Misiara, A.C. Chauveau, D. Chirpaz-Cerbat, P. Daniel-Thomas, M. Lacroix, L. Maurice
    CEA/IRFU, Gif-sur-Yvette, France
  • M. Desmons, A. Dubois, A. Gaget, L. Napoly, M. Oublaid, G. Perreu, O. Piquet, B. Pottin, Y. Sauce
    CEA/DRF/IRFU, Gif-sur-Yvette, France
 
  The RF power coupler system for the RFQ of the ESS LINAC will feed 1.6 MW peak power through two coaxial loop couplers for a 352.21 MHz operation at the expected duty cycle. A specific test stand has been designed to condition the power couplers, and test the different auxiliary components in the nominal conditions of the RFQ. The power couplers were successfully assembled, installed and instrumented on the test cavity. This paper presents the general layout of the test stand, the installation and preparation of the power couplers for their conditioning at high RF power up to the ESS nominal conditions.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF004  
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WEPMF009 Influence of Argon-Ion Irradiation on Field Emission from Polycrystalline Cu and Large-Grain NB Surfaces radiation, niobium, experiment, cavity 2384
 
  • S. Soykarci
    University of Wuppertal, Wuppertal, Germany
  • D. Lützenkirchen-Hecht, V. Porshyn, P. Serbun
    Bergische Universität Wuppertal, Wuppertal, Germany
 
  Funding: This work is funded by the BMBF project 05H15PXRB1.
In the present work, systematic investigations of the enhanced field emission (EFE) from polycrystalline copper and large grain niobium surfaces before and after argon-ion irradiation with an energy of 5 keV were performed with a variation of the irradiation time. Results show that the suppression of the EFE might be achievable.
 
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WEPMF022 Coulped Multiphysics Simulation for the Water Cooling Layout of a Rhodotron Cavity cavity, simulation, operation, electron 2416
 
  • L. Yang, X. He, H. Li, S.Q. Liao
    CAEP/IFP, Mainyang, Sichuan, People's Republic of China
 
  A Rhodotron-based electron accelerator served as micro-focused X-ray source is under development at IFP, CAEP. The RF-cavity, running in long pulse/ CW mode, will deliver 9 MeV energy to electron beams after multiple accelerations within the same field at a frequency of 107.5MHz. A substantial amount of average power loss with tens of kW will be dissipated on the RF surface of the cavity to maintain the operational field level. Efficient water cooling is critical to prevent large scale temperature rise for stable operation sake. Reasonable prediction of temperature rise becomes essential to assess a certain cooling layout in the design phase. The frequency drift and thermal stress on account of temperature variation and gradient on cavity wall respectively, could be computed accordingly. This paper presents a comprehensive coupled simulation involving electromagnetic, thermal and structural for the RF-cavity of Rhodotron.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF022  
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WEPMF031 Development of a High-Power High-Directivity Directional Coupler and Four Power Dividers for S-Band coupling, GUI, MMI, simulation 2422
 
  • X. He, J. Lei, J.R. Zhang
    IHEP, Beijing, People's Republic of China
 
  A novel Bethe-hole S band directional coupler has been designed based on some structural optimizations, the prototype has been tested with a Directivity of more than 30 dB. The new directional coupler can also hold higher power compared to the old type, which is more useful for the future accelerator applications. Four power dividers using different structures are studied and the best one is chosen for fabrication. The prototype with matching rod in the middle has got qualified microwave cold test results and has been used during the whole microwave commissioning of an accelerating structure, the performance is quite stable.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF031  
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WEPMF032 Experimental Studies on Secondary Electron Emission Characteristics for Chamber Materials of Accelerators electron, experiment, detector, neutron 2425
 
  • Y. Jiao, Z. Duan, W.B. Liu, Y.D. Liu
    IHEP, Beijing, People's Republic of China
  • Liu. S. Liu
    Institute of High Energy Physics (IHEP), People's Republic of China
  • P.C. Wang
    DNSC, Dongguan, People's Republic of China
 
  Funding: National Natural Science Foundation of China (11275221) and Key Laboratory Foundation of Particle Acceleration Physics &Technology (Y5294106TD)
Secondary electron emission (SEE) of surface is origin of multipacting effect which could seriously deteriorate beam quality and even perturb the normal operation of particle accelerators. Experimental measurements on secondary electron yield (SEY) on different materials and coating have been developed in many accelerator laboratory. In fact, the SEY is just one parameter of secondary electron emission characteristics which include spatial and energy distribution of emitted electrons. A novel experimental apparatus was set up in China Spallation Neutron Source (CSNS) and innovative measurement methods were applied to obtain the whole characteristics of SEE. With some traditional accelerator chamber materials such as Cu, Al, TiN, SEY dependence on primary electron energy and beam injection angle, spatial and energy distribution of emitted secondary electrons were achieved with this measurement apparatus. This contribution also tries to give all the experimental results a reasonable theoretical analysis.
 
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WEPMF033 RF Study And Cold Test of an S-band Spherical Cavity Pulse Compressor cavity, coupling, simulation, klystron 2429
 
  • J. Lei, X. He, M. Hou, X.P. Li, G. Pei, H. Wang, J.B. Zhao
    IHEP, Beijing, People's Republic of China
  • S. Shu
    Institute of High Energy Physics (IHEP), Chinese Academy of Sciences, Beijing, People's Republic of China
 
  An S-band (2856 MHz) spherical cavity pulse compressor has been designed, fabricated and tested in the Institute of High Energy Physics (IHEP), Chinese Academy of Sciences (CAS). The pulse compressor consists of a special 3 dB coupler and only one spherical energy storage cavity, two TE114 modes are chosen to oscillate in which for fairly high unload Q factor. The prototype was made of aluminum for studying the performance of the pulse compressor and checking the validity of the simulations. The cold test results of the aluminum cavity are also presented. The copper coating on the whole internal surface of the aluminum spherical cavity is in progress and the test results will also be presented in the future.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF033  
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WEPMF036 RF Test Result of a BNL N-Doped 500 MHz B-Cell Cavity at Cornell cavity, SRF, superconducting-cavity, niobium 2440
 
  • F. Furuta, M. Ge, T. Gruber, J.J. Kaufman, M. Liepe, J.T. Maniscalco, J. Sears
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • F. Gao, J. Rose
    BNL, Upton, Long Island, New York, USA
 
  Cornell's SRF group has collaborated with Brookhaven National Laboratory (BNL) on one 500 MHz CESR type SRF "B-cell" cavity (BNL B-cell) for the National Synchrotron Light Source II. Cornell has been responsible for RF surface preparation, vertical testing, and short cavity string assembly. As a state-of-the-art surface preparation protocol, Cornell selected Nitrogen doping for the BNL B-cell. N-doping has been well demonstrated and established to push the cavity quality factor (Q0) higher in 1.3GHz SRF cavities at many laboratories. Cornell calculated that N-doping could also be beneficial on a 500MHz SRF cavity, with a potential to increase its Q0 by a factor of two compared with the traditional chemical polishing based surface preparation protocol. Here we report on the detailed surface preparation and vertical test result of the BNL B-cell.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF036  
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WEPMF039 Experimental Results on the Field and Frequency Dependence of the Surface Resistance of Niobium Cavities cavity, niobium, experiment, electron 2451
 
  • P.N. Koufalis, M. Liepe, J.T. Maniscalco, T.E. Oseroff
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  We investigate the field and frequency dependence of the surface resistance of single-cell niobium cavities as a function of surface treatment at 1.3, 2.6, and 3.9 GHz. The surface resistance is broken down into two parts: the temperature-independent residual resistance and the temperature-dependent BCS resistance. While the low-field BCS resistance is known to vary quadratically with frequency, the exact dependence of the BCS and residual resistances on field at higher frequencies are important topics for further investigation. We offer results on a systematic experimental study of the residual and BCS resistance as a function of frequency and field for clean niobium and high-temperature nitrogen-doped niobium.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF039  
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WEPMF055 The REGAE Accelerator Vacuum System gun, cathode, operation, electron 2493
 
  • S. Lederer, K. Flöttmann, L. Lilje, N. Plambeck
    DESY, Hamburg, Germany
 
  Since 2011 the Relativistic Electron Gun for Atomic Exploration (REGAE) is operated at DESY in Hamburg. The accelerator consists mainly of a high gradient S-band RF-gun, which generates ultra-low emittance electron bunches, and an S-band RF-buncher cavity for bunch compression. In this contribution we describe the vacuum system of the REGAE accelerator. We will cover design aspects, applied cleaning and installation procedures as well as operation experience over the last years.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF055  
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WEPMF057 PETRA III Vacuum System - Experiences from the First Decade of Operation operation, radiation, photon, experiment 2499
 
  • L. Lilje, R. Bospflug, N. Plambeck
    DESY, Hamburg, Germany
 
  In 2008 the construction of the PETRA III vacuum system started. A year later the first photons were delivered to initial experiments and in 2010 the user operation started. In this paper the operation of the vacuum system will be reviewed. Some of the lessons learned in the initial phase will be presented as well as the main upgrades since then. By now the vacuum system has shown a very high reliability and shows no significant impact on the availability of the machine.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF057  
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WEPMF066 Fabrication of Split-Section X-band Structure Using Elastic Averaging alignment, coupling, electron, gun 2521
 
  • P. Borchard, S.A. Appert, J.S. Hoh
    Dymenso LLC, San Francisco, USA
 
  Conventional accelerator structures are manufactured using axial stacks of cylindrical components which, when brazed together, form the accelerator cell structure. Splitting the accelerator structure into two sections along the beam axis allows for a significant reduction in part count and vacuum joint length. The resultant single and coplanar vacuum joint between the two split sections allows for joining techniques such as electron beam welding or brazing of the parts to form the accelerator vacuum envelope. High precision alignment of the two sections is achieved through an elastic averaging interface coupling where improved accuracy is derived from the averaging of errors over a large number of relatively compliant contacting members. The monoblock split sections allow for highly optimized cooling configurations with enhanced heat removal in high heat flux regions, reducing vacuum wall thermal stresses and enabling higher power operation. This paper describes the engineering and manufacturing of four generations of brazed and electron beam welded X-band accelerator structures at both 9.3 GHz and 11.4 GHz frequencies.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF066  
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WEPMF068 Inexpensive Brazeless Accelerator Prototype gun, cavity, operation, electron 2528
 
  • S.P. Antipov, R.A. Kostin, S.V. Kuzikov
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • A.A. Vikharev
    IAP/RAS, Nizhny Novgorod, Russia
 
  Funding: DOE SBIR
A simple, inexpensive way to manufacture a standard radio frequency (RF) driven particle accelerator is presented. The simplification comes from two innovations: utilization of LCLS gun type RF design to avoid an expensive brazing process and copper plating of stainless steel that further reduces manufacturing cost. This is realized by a special structure design where accelerating structure cells are made out of copper plated stainless steel with knife edges and structure irises - copper disks acts also as gaskets for vacuum and RF seal. Besides the reduced cost, brazeless assembly allows integration of effective cooling and magnet optics elements into accelerator cells. Here we report on manufacturing and testing of brazeless accelerator prototype.
 
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WEPMF074 High Power Conditioning of X-Band RF Components operation, cavity, hardware, GUI 2545
 
  • N. Catalán Lasheras, H. Damerau, R.L. Gerard, A. Grudiev, G. McMonagle, J. Paszkiewicz, A. Solodko, I. Syratchev, B.J. Woolley, W. Wuensch, V. del Pozo Romano
    CERN, Geneva, Switzerland
  • T.G. Lucas, M. Volpi
    The University of Melbourne, Melbourne, Victoria, Australia
  • S. Pitman
    Lancaster University, Lancaster, United Kingdom
  • A. Vnuchenko
    IFIC, Valencia, Spain
 
  As part of the effort to qualify CLIC accelerating struc-tures prototypes, new X-band test facilities have been built and commissioned at CERN in the last years. In this context, a number of RF components have been designed and manufactured aiming at stable operation above 50 MW peak power and several kW of average power. All of them have been tested now in the X-band facility at CERN either as part of the facility or in dedicated tests. Here, we describe shortly the main design and manufac-turing steps for each component, the testing and eventual conditioning as well as the final performance they achieved.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF074  
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WEPMF078 Assembly of the DQW Crab Cavity Cryomodule for SPS Test cavity, cryomodule, controls, alignment 2561
 
  • M. Garlaschè, K. Artoos, R. Calaga, O. Capatina, T. Capelli, N. El Kbiri, D. Lombard, P.F. Marcillac, P. Minginette, M. Narduzzi, L.R.A. Renaglia, J. Roch, J.S. Swieszek
    CERN, Geneva, Switzerland
  • A. Krawczyk, B. Prochal
    IFJ-PAN, Kraków, Poland
 
  RF Crab Cavities are an essential part of the High Luminosity Upgrade of the LHC accelerating complex. Two concepts of such superconducting systems are being developed: the Double Quarter Wave (DQW) and the RF Dipole (RFD). A prototype cryomodule - hosting two DQW cavities - has been fabricated and assembled for validation tests to be carried out in the Super Proton Synchrotron (SPS) at CERN. An overview of the main cryomodule components is presented, together with the system features and main fabrication requirements. The preparatory measures for cryomodule assembly, the execution and lessons learned are also discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF078  
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WEPMF082 Design and Construction of the CERN PS Booster Charge Exchange Injection Chicane Bumpers injection, septum, simulation, linac 2575
 
  • B. Balhan, C. Baud, J.C.C.M. Borburgh, M. Hourican
    CERN, Geneva, Switzerland
 
  In the framework of the LIU project and the connection from LINAC4 to PS Booster, the 160 MeV H beam will be injected horizontally into the PSB by means of one charge-exchange injection system for each PSB ring. A set of four outside vacuum pulsed dipole magnets (BSW) creating the required injection bump has been designed and built. The dynamic requirements for the bump ramp down determine, to a large extent, the field homogeneity due to the eddy currents induced in the corrugated Inconel vacuum chamber. Magnetic simulations were performed to determine the field harmonics during bump ramp down, and the results subsequently used for the dynamic tracking of the beam during injection. The mechanical design and construction of the magnets will be briefly outlined, and the article will conclude with the magnetic measurements of the magnets. The magnetic performance of the as built magnets will be compared with the simulations and the influence of the vacuum chambers on the magnetic field will be quantified.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF082  
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WEPMF087 LHC Injectors Upgrade Project: Outlook of the Modifications to the Super Proton Synchrotron (SPS) Vacuum System and Impact on the Operation of the Carbon-Coated Vacuum Chambers impedance, experiment, proton, extraction 2589
 
  • C. Pasquino, G. Bregliozzi, P. Chiggiato, P. Cruikshank, A. Farricker, A. Harrison, J. Perez Espinos, J.A.F. Somoza, M. Taborelli, C. Vollinger
    CERN, Geneva, Switzerland
 
  Aiming at doubling the beam intensity and reducing the beam emittance, significant modifications of the LHC and its injector chain will take place during Long Shutdown 2 (LS2), starting from 2019. The LIU project (LHC Injector Upgrade), in the specific, touches Linac4, the Proton Synchrotron Booster (PSB), the Proton Synchrotron (PS), the Super Proton Synchrotron (SPS) as well as the heavy ion chain. During LS2, important changes will take place mainly in the Long Straight Sections of the SPS to host a newly conceived dumping system, upgraded RF cavities and upgraded extraction channels. Additionally, the vacuum chambers of the main bending and focusing magnets as well as vacuum drifts will be coated with amorphous carbon in order to reduce the dynamic pressure effects induced by multipacting. The modifications to the different vacuum sectors will be described in details as well as the impact on operation of amorphous carbon coated sectors that have been already deposited.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF087  
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WEPMF090 Upgrade of the CMS Experimental Beam Vacuum During LS2 experiment, detector, operation, luminosity 2596
 
  • J.S. Sestak, G. Bregliozzi, P. Chiggiato, C. Di Paolo
    CERN, Geneva, Switzerland
 
  Starting from December 2018, the Large Hadron Collider (LHC) is going to interrupt its physic operations for more than two years within the period called second long shutdown (LS2). The Compact Muon Solenoid (CMS) experiment will undergo the biggest upgrade of its experimental beam vacuum system since the first operations in 2008. The new experimental vacuum layout should comply with demanding structural, vacuum, integration and physics requirements. Moreover, the new layout should be compatible with foreseen engineering changes of the detector and the machine during the upgrade phase of High-Luminosity LHC in LS3. This paper gives an overview of the CMS LS2 experimental vacuum sectors upgrades. Both design and production phase of the new vacuum layout is discussed in detail.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF090  
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WEPMG001 Engineering Design and Prototyping of the New LIU PS Internal Beam Dumps simulation, interface, proton, operation 2600
 
  • G. Romagnoli, J.A. Briz Monago, M.E.J. Butcher, M. Calviani, D.G. Cotte, Y. C. Coutron, J.J. Esala, E. Grenier-Boley, J. Hansen, A. Huschauer, A. Masi, F.-X. Nuiry, D. Steyart, V. Vlachoudis
    CERN, Geneva, Switzerland
 
  For the LHC Injectors Upgrade (LIU) at CERN, the two Proton Synchrotron (PS) internal dumps are redesigned and upgraded for the new high intensity/brightness beams. The dumps are installed as active elements in the lattice in straight sections between the main bending magnets. The dumps are moved into the beam when requested by operation and shave the circulating beam turn by turn stopping the beam after about 6 ms. The shaving induces a very localized beam energy deposition on the dump surface in a thickness of tens of microns. A completely new approach has been developed with FLUKA to simulate beam shaving, coupled with ANSYS to define a new dump core design. This paper presents the design of the dump based on operational constraints such as cycling 200 000 times per year for 20 years, limited access for maintenance or reaching the beam trajectory in 150 ms. These constraints had a major impact on the technological choices. The new dump core is made of a low-density graphite block followed by a denser copper alloy (CuCr1Zr) one. Water circuits, bonded with Hot Isostatic Pressing, are cooling the core in ultra-high vacuum. The core is moved by a spring-based actuation mechanism.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMG001  
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WEPMG005 First Beam Test of Laser Engineered Surface Structures (LESS) at Cryogenic Temperature in CERN SPS Accelerator electron, laser, cryogenics, multipactoring 2616
 
  • R. Salemme, V. Baglin, S. Calatroni, P. Chiggiato, B. Di Girolamo, E. Garcia-Tabares Valdivieso, B. Jenninger, L. Prever-Loiri, M. Sitko
    CERN, Geneva, Switzerland
  • A. Abdolvand, S. Wackerow
    University of Dundee, Nethergate, Dundee, Scotland, United Kingdom
  • R. Salemme
    ITER Organization, St. Paul lez Durance, France
 
  Electron cloud mitigation is an essential requirement for accelerators of positive particles with high intensity beams to guarantee beam stability and limited heat load in cryogenic systems. Laser Engineered Surface Structures (LESS) are being considered, within the High Luminosity upgrade of the LHC collider at CERN (HL-LHC), as an option to reduce the Secondary Electron Yield (SEY) of the surfaces facing the beam, thus suppressing the elec-tron cloud phenomenon. As part of this study, a 2.2 m long Beam Screen (BS) with LESS has been tested at cryogenic temperature in the COLD bore EXperiment (COLDEX) facility in the SPS accelerator at CERN. In this paper, we describe the manufacturing procedure of the beam screen, the employed laser treatment technique and discuss our first observations in COLDEX confirming electron cloud suppression.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMG005  
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WEPMK001 Preliminary Design of a Cooling System for the LHC Injection Kicker Magnets kicker, injection, operation, impedance 2624
 
  • L. Vega Cid, M.J. Barnes, L. Ducimetière, M.T. Moester, V. Vlachodimitropoulos, W.J.M. Weterings
    CERN, Geneva, Switzerland
  • A. Abánades
    ETSII UPM, Madrid, Spain
 
  The CERN Large Hadron Collider (LHC) is equipped with two fast pulsed magnet systems (MKIs) that inject particle beams from the injector chain. Future operation for High Luminosity LHC (HL-LHC) with high intensity beams will cause heating of the ferrite yokes of the MKIs beyond their Curie temperature, preventing injection until the yokes cool down. Beam coupling impedance studies show that it is possible to move a substantial portion of the beam induced power deposition from the upstream ferrite yokes, which are the yokes with the highest power deposition, to ferrite rings located at the upstream end of the magnet. Thermal predictions show that this power redistribution, combined with the installation of a cooling system around the rings, will maintain the temperatures of all the yokes and ferrite rings below their Curie point. Since the rings are not pulsed to high voltage, whereas the ferrite yokes are, the installation of a cooling system is feasible around the rings. The proposed design of the cooling system will be tested to ensure good performance before its installation on the MKIs. The details of the simulations and the design process are reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMK001  
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WEPMK002 Longitudinal Impedance Analysis of an Upgraded LHC Injection Kicker Magnet impedance, kicker, simulation, injection 2628
 
  • V. Vlachodimitropoulos, M.J. Barnes, L. Vega Cid, W.J.M. Weterings
    CERN, Geneva, Switzerland
 
  Prior to Long Shutdown 1 (LS1) one of the LHC injection kickers (MKIs) occasionally exhibited high temperatures leading to significant turnaround times. After a successful impedance mitigation campaign during LS1, the MKI ferrite yokes have remained below their Curie point and have not limited LHC's availability. However, for HL-LHC operation the MKI yokes are expected to exceed their Curie temperatures after long physics runs. To ensure uninterrupted future HL-LHC operation, a modified beam screen design, relocating some of the heat load to more easily cooled parts, and a suitable cooling system are under development as the current baseline for the HL-LHC upgrade of the MKIs. An upgraded beam screen providing such relocation has been designed, simulated and compared to the existing model. To validate simulations, two longitudinal beam coupling impedance measurement techniques have been used and the results are compared to predictions. The modified beam screen was implemented in an upgraded MKI installed in the LHC during the Year End Technical Stop (YETS) 2017/18.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMK002  
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WEPMK003 An Upgraded LHC Injection Kicker Magnet kicker, injection, electron, impedance 2632
 
  • M.J. Barnes, C. Bracco, G. Bregliozzi, A. Chmielinska, L. Ducimetière, B. Goddard, T. Kramer, H. Neupert, L. Vega Cid, V. Vlachodimitropoulos, W.J.M. Weterings, C. Yin Vallgren
    CERN, Geneva, Switzerland
  • A. Chmielinska
    EPFL, Lausanne, Switzerland
 
  Funding: Work supported by the HL-LHC project.
An upgrade of the LHC injection kickers is necessary for HL-LHC to avoid excessive beam induced heating of these magnets: the intensity of the HL-LHC beam will be twice that of LHC. In addition, in the event that it is necessary to exchange an injection kicker magnet, the newly installed kicker magnet would limit HL-LHC operation for a few hundred hours due to dynamic vacuum activity. Extensive studies have been carried out to identify practical solutions to these problems: these include redistributing a significant portion of the beam induced power deposition to ferrite parts of the kicker magnet which are not at pulsed high voltage and water cooling of these parts. Furthermore a surface coating, to mitigate dynamic vacuum activity, has been selected. The results of these studies, except for water cooling, have been implemented on an upgraded LHC injection kicker magnet: this magnet was installed in the LHC during the 2017-18 Year End Technical Stop. This paper presents the upgrades, including some test and measurement results.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMK003  
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WEPMK010 LCLS-II Cryomodules Production at Fermilab cryomodule, cavity, FEL, controls 2652
 
  • T.T. Arkan, J.N. Blowers, C.M. Ginsburg, C.J. Grimm, J.A. Kaluzny, A. Lunin, Y.O. Orlov, K.S. Premo, R.P. Stanek, G. Wu
    Fermilab, Batavia, Illinois, USA
 
  Funding: DOE
LCLS-II is a planned upgrade project for the linear coherent light source (LCLS) at SLAC. The LCLS-II linac will consist of thirty-five 1.3 GHz and two 3.9 GHz superconducting RF continuous wave (CW) cryomodules that Fermilab and Jefferson Lab are currently producing in collaboration with SLAC. The LCLS-II 1.3 GHz cryomodule design is based on the European XFEL pulsed-mode cryomodule design with modifications needed for CW operation. Two prototype cryomodules had been assembled and tested. After prototype cryomodule tests, both laboratories have increased cryomodule production rate to meet the challenging LCLS-II project installation schedule requirements of approximately one cryomodule per month per laboratory. Fermilab is at half point for the production, meaning that 6 cryomodules are fully assembled and tested. This paper presents Fermilab Cryomodule Assembly Facility (CAF) infrastructure for the LCLS-II cryomodules assembly, production experience at the half point emphasizing the challenges and mitigations.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMK010  
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WEPML014 Tooling Systems for the Assembly and Integration of the SSR1 Cryomodule for PIP-II Project at Fermilab cavity, cryomodule, solenoid, insertion 2710
 
  • D. Passarelli, F. Di Ciocchis, M. Parise, V. Roger
    Fermilab, Batavia, Illinois, USA
 
  In this paper we present the assembly strategy and tooling design for the SSR1 cryomodule from the cavity string to the final module. Several challenging aspects were considered to minimize undesired stresses on critical components, to preserve the alignment of cavities and solenoids during final assembly, and ultimately to meet the technical requirements of the PIP-II project at Fermilab.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML014  
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WEPML015 Preparation and Qualification of Jacketed SSR1 Cavities for String Assembly at Fermilab cavity, cryomodule, multipactoring, controls 2714
 
  • D. Passarelli, P. Berrutti, S.K. Chandrasekaran, J.P. Ozelis, M. Parise, L. Ristori, A.M. Rowe, A.I. Sukhanov
    Fermilab, Batavia, Illinois, USA
 
  The qualification of dressed 325 MHz Single Spoke Resonators type 1 (SSR1) to meet technical requirements is an important milestone in the development of the SSR1 cryomodule for the PIP-II Project at Fermilab. This paper reports the procedures and lessons learned in processing and preparing these cavities for horizontal cold testing prior to integration into a cavity string assembly.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML015  
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WEPML028 NEG Coated Vacuum Chambers and Bake-Out-Concept for the HESR at FAIR dipole, quadrupole, heavy-ion, storage-ring 2745
 
  • H. Jagdfeld, N.B. Bongers, J. Böker, P. Chaumet, F.M. Esser, F. Jordan, F. Klehr, G. Langenberg, D. Prasuhn, L. Semke, R. Tölle
    FZJ, Jülich, Germany
  • A. Mauel, G. Natour, U. Pabst
    Forschungszentrum Jülich GmbH, Central Institute of Engineering, Electronics and Analytics, Jülich, Germany
 
  The High-Energy Storage Ring (HESR) is part of the international Facility for Antiproton and Ion Research (FAIR) at GSI Darmstadt. Forschungszentrum Jülich (IKP and ZEA-1) is responsible for the design and installation of the HESR. The HESR is designed for antiprotons and heavy ion experiments as well. Therefore the vacuum is required to be 10-11 mbar or better. To achieve this extreme high vacuum (XHV), NEG coated chambers will be used in combination with common vacuum pumps to reach the needed pumping speed and capacity everywhere in the accelerator ring. For activation of the NEG material a bake-out system will be developed and installed. A bake-out test bench was used for checking the achievable end pressure and developing the bake-out system for the NEG coated chambers of the HESR. The results of the tests and the bake-out concept including the layout of the control system are presented. In addition, the temperature distribution of the dedicated heater jackets inside the dipole and quadrupole magnets are shown.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML028  
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WEPML029 Vacuum System of the HESR at FAIR, Status of Tests, Layout and Manufacturing dipole, kicker, injection, controls 2748
 
  • F.M. Esser, N.B. Bongers, J. Böker, P. Chaumet, R. Gebel, R. Greven, S. Hamzic, H. Jagdfeld, F. Klehr, B. Laatsch, G. Langenberg, D. Marschall, A. Mauel, G. Natour, D. Prasuhn, L. Reifferscheidt, M. Schmitt, L. Semke, R. Tölle
    FZJ, Jülich, Germany
 
  The Research Center Jülich is leading a consortium being responsible for the design and manufacturing of the High-Energy Storage Ring (HESR) which is part of the FAIR project in Darmstadt, Germany. The HESR is designed for antiprotons within a momentum range of 1.5-15 GeV/c but can also be used for heavy ion experiments. Therefore the vacuum quality is expected to be 10-11 mbar or better which is a great challenge on the overall vacuum layout as well as on the surface quality of the chambers and beam tubes. Whereas all bent dipole chambers are installed, the manufacturing of the pumping bodies with integrated RF meshes as well as several diagnostic chambers are in the focus of investigation. To validate the intended pumping concept of both the bake-out arc sections and the non-bakable straight sections, final tests at the operational test benches are planned. In parallel, the purchasing of valves and first pumps will be prepared. The actual layout of the HESR vacuum system and its components will be presented as well as the progress of manufacturing of several vacuum chambers. The latest experimental test results will be presented also.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML029  
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WEPML038 Plasma Window as a Pressure Valve for FAIR plasma, cathode, experiment, electron 2776
 
  • B. F. Bohlender, M. Iberler, J. Jacoby
    IAP, Frankfurt am Main, Germany
  • A. Michel
    Goethe Universität Frankfurt, Frankfurt am Main, Germany
 
  Funding: Funded by BMBF, Ref. No: 05P15 RFRBA and HIC for FAIR
This contribution shows the progress in the development of a plasma window at the institute for applied physics at Goethe University Frankfurt. A plasma window* is a membrane free transition between two regions of different pressure, enabling beam transmission from a rough vacuum area (~1 mbar) to a higher pressure (up to 1 bar) region on short length scales. In comparison to differential pumping stages a length reduction by a factor of up to 100 is achievable, while the absence of a solid membrane yields prolonged operation time. The sealing effect is based on the high temperature arc discharge sustained in a cooled copper channel between the pressure regimes. Due to a bulk temperature around 10,000K** the viscosity of the gas is dramatically increased, leading to a slower gas flow, enabling a higher pressure gradient. This contribution will present first results regarding the pressure gradient in dependence of the discharge current and the aperture. Until now, a pressure factor around 100 has been established for well over 50 min. This contribution goes along with the one from Mr. A. Michel, he focuses on the spectroscopic analysis of the arc plasma.
*A. Hershcovitch, J. Appl. Phys., AIP Publishing (1995) 78, 5283
**Y.E. Krasik et al., "Plasma Window Characterization", J. Appl. Phys., AIP Publishing (2007) 101, 053305.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML038  
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WEPML045 Infrastructure for Superconducting CH-Cavity Preparation at HIM cavity, linac, SRF, heavy-ion 2796
 
  • T. Kürzeder, K. Aulenbacher, W.A. Barth, F.D. Dziuba, V. Gettmann, M. Miski-Oglu, E. Riehn
    HIM, Mainz, Germany
  • K. Aulenbacher, R.G. Heine, T. Stengler
    IKP, Mainz, Germany
  • W.A. Barth, S. Yaramyshev
    GSI, Darmstadt, Germany
  • F. Hug
    KPH, Mainz, Germany
 
  A superconducting cw LINAC for heavy ions is currently under development at GSI in Darmstadt and HIM in Mainz. This Linac is based on 217 MHz multigap bulk niobium Crossbar H-mode RF-cavities. In order to treat and prepare RF-cavities with such a complex geometry a new cleanroom facility has been already built at the Helmholtz-Institut in Mainz. All tools and machines inside the cleanroom can handle cavities with up to 800 mm in diameter and with up to 1300 mm in length. In its ISO-class 6 and 4 zones, respectively it features a large ultrasonic and conductance rinsing bath, a high pressure rinsing (HPR) cabinet and a vacuum oven. The HPR cabinet has an inside clearance of 1.4 m. The large cavities sit on a rotating table, while the rising wand moves vertically up and down. Due to the crossbar structure of the RF-cavities the HPR device allows for off axis-rinsing in their quadrants. For RF testing a 52 m² (4 m x 13 m) concrete shielded area with sufficient liquid helium and nitrogen supply is located next to the cleanroom and the cryo-module assembly area. We will report on the new SRF infrastructure in Mainz and the commissioning of the new high pressure rinsing cabinet.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML045  
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WEPML053 Availability of the TiN Coating-Free Ceramic in the STF-type Power Coupler for ILC electron, SRF, cryomodule, GUI 2819
 
  • Y. Yamamoto, E. Kako, T. Matsumoto, S. Michizono, A. Yamamoto
    KEK, Ibaraki, Japan
  • M. Irikura, M. Ishibashi, H. Yasutake
    Toshiba Electron Tubes & Devices Co., Ltd (TETD), Tochigi, Japan
  • C. Julie, E. Montesinos
    CERN, Geneva, Switzerland
 
  In the Superconducting RF Test Facility (STF) in KEK, the research and development for the power coupler with the TiN coating-free ceramic has been done from 2014. In 2016, the high power test at the test bench was stopped due to the worse vacuum level by the unusual heating around the RF window with the TiN coating-free ceramic and the coaxial tapered section, which was caused by the enormous emission of the secondary electrons from the ceramic. And, the situation was never also changed by the ultrapure water rinsing for the power couplers several times. However, in 2017, the ultrasonic rinsing was done for the power couplers for the first time by the collaboration between KEK and TETD. After that, the situation was drastically improved, and the secondary electron emission almost disappeared even in the higher RF duty. This shows that the TiN coating-free ceramic is the prospective item for the cost reduction in ILC. In this report, the recent result for the power coupler with the TiN coating-free ceramic will be presented in detailed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML053  
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WEPML057 First Commissioning of Vacuum System of Positron Damping Ring for SuperKEKB photon, MMI, operation, positron 2826
 
  • K. Shibata, H. Hisamatsu, T. Ishibashi, K. Kanazawa, M. Shirai, Y. Suetsugu, S. Terui
    KEK, Ibaraki, Japan
 
  To satisfy the requirements of high beam quality for positron injection into the SuperKEKB main ring, a new damping ring (DR) is constructed in an upgraded injector system. The DR is a racetrack-shaped storage ring with a circumference of 135.5 m, in which the 1.1 GeV positron beam is stored for 40 ms to damp the emittance. The maximum stored beam current is 70.8 mA. Required beam lifetime due to residual gas scattering is longer than 1000 s and the average pressure should be lower than 10-5 Pa. Non-evaporable getter (NEG) pumps are mainly used, and the average effective pumping speed for CO is expected to be 0.013 m3s−1m-1 immediately after NEG activation. The beam pipes are made of aluminum alloy, and have antechambers to deal with synchrotron radiation (critical energy 0.8-0.9 keV, total power 7.2 kW) in arc sections, which are effective in reducing the electron cloud and the impedance of the beam pipes. As additional countermeasures against the electron cloud effect, TiN coating and grooved surfacing are also adopted. The commissioning of the DR will commence at the beginning of 2018. The status of the vacuum system of the DR during the first commissioning will be reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML057  
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WEPML059 Status of the SuperKEKB Vacuum System in the Phase-2 Commissioning MMI, electron, wiggler, permanent-magnet 2833
 
  • Y. Suetsugu, H. Hisamatsu, T. Ishibashi, K. Kanazawa, K. Shibata, M. Shirai, S. Terui
    KEK, Ibaraki, Japan
 
  The SuperKEKB is an electron-positron collider with asymmetric energies in KEK aiming an extremely high luminosity of 8.0·1035 /cm2/s. In the Phase-1 commissioning from February to June, 2016, the vacuum system of the main ring worked well as a whole at stored beam currents of approximately 1 A. However, several problems were found for the future commissioning, and various countermeasures were taken against these problems during the shutdown period before starting the Phase-2 commissioning. For example, permanent magnets were placed around the beam pipe to suppress the electron cloud effect in the positron ring. Other than these works, new beam pipes for the collision point, the super-conducting final focusing magnets and the positron beam injection region were installed in the main ring. Additional six beam collimators were installed for reducing background noise of the particle detector. Furthermore, the vacuum system for new damping ring for the positron beam was constructed. Reported here will be the present status of the vacuum system of the main ring, and major results of the countermeasures taken prior to the Phase-2 commissioning.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML059  
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WEPML069 Fast Kicker and Pulser R&D for the HEPS on-Axis Injection System kicker, injection, impedance, simulation 2846
 
  • H. Shi, J. Chen, Z. Duan, L. Huo, P. Liu, X.L. Shi, G. Wang, L. Wang, N. Wang
    IHEP, Beijing, People's Republic of China
 
  The HEPS plans to adopt on-axis injection scheme because the dynamic aperture of machine is not large enough for off-axis injection for its baseline 7BA lattice design. A sets of super fast kicker and pulser of ±15kV amplitude, 15ns pulse bottom width are needed for bunch spacing of 10ns to minimize perturbation on adjacent bunches. To achieve these requirement, a multifaceted R&D program including the strip-line kicker and HV pulser, was initiated last 2 years. So far, the prototype development of a 750mm long strip-line kicker and a DSRD pulser was completed and the preliminary test results show they can meet the baseline requirement of the HEPS.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML069  
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WEPML071 Superconducting 16-Pole Wiggler for Beijing Electron-Positron Collider II wiggler, impedance, collider, positron 2853
 
  • M.X. Li, X.J. Bian, F.S. Chen, W. Chen, X.J. Sun, H. Wang, J.L. Wang, N. Wang, M.F. Xu, X.C. Yang
    IHEP, Beijing, People's Republic of China
 
  A superconducting 16-pole 2.6T wiggler with period 170mm of The High-Energy Photon Source and the Test Facility Project (HEPS-TF) designed and fabricating in the Institute of High Energy Physics (IHEP) in China is described. This wiggler will be installed in Beijing Electron-Positron Collider II (BEPCII). The main parameters and structure of the wiggler are presented. Besides, some vertical testing results are involved.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML071  
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WEPML072 Gas Permeability Measurement of Graphene Films background, experiment, neutron, detector 2856
 
  • P.C. Wang, X. Sun
    DNSC, Dongguan, People's Republic of China
  • Liu. S. Liu
    Institute of High Energy Physics (IHEP), People's Republic of China
  • C. Meng, H. Wang, D.H. Zhu
    IHEP, Beijing, People's Republic of China
 
  Graphene has extremely high strength and thermal conductivity, which can possibly be used for high-power beam window in accelerator. In this paper, gas permeabilities of different graphene films have been measured by the permeation measurement facility. According to the results, the possibility of the graphene-made beam windows will be discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML072  
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THXGBD3 Status of the ESRF-Extremely Brilliant Source Project SRF, operation, injection, dipole 2882
 
  • J.-L. Revol, C. Benabderrahmane, P. Berkvens, J.C. Biasci, J-F. B. Bouteille, T. Brochard, N. Carmignani, J.M. Chaize, J. Chavanne, F. Cianciosi, A. D'Elia, R.D. Dimper, M. Dubrulle, D. Einfeld, F. Ewald, L. Eybert, G. Gautier, L. Goirand, L. Hardy, J. Jacob, B. Joly, M.L. Langlois, G. Le Bec, I. Leconte, S.M. Liuzzo, C. Maccarrone, T.R. Mairs, T. Marchial, H.P. Marques, D. Martin, J.M. Mercier, A. Meunier, M. Morati, J. Pasquaud, T.P. Perron, E. Plouviez, E. Rabeuf, P. Raimondi, P. Renaud, B. Roche, K.B. Scheidt, V. Serrière, P. Van Vaerenbergh, R. Versteegen, S.M. White
    ESRF, Grenoble, France
 
  The ESRF - the European Synchrotron Radiation Facility - is a user facility in Grenoble, France, and the source of intense high-energy (6 GeV) X-rays. In 2019, the existing storage ring will be removed and a new lattice will be installed in its place, dramatically reducing the equilibrium horizontal emittance. This 'fourth-generation' synchrotron will produce an X-ray beam 100 times more brilliant and coherent than the ESRF source today. The Extremely Brilliant Source (EBS) project was launched in 2015 and is now well underway, on track for its scheduled completion in 2020. The design is completed, the procurement in full swing, the assembly has started, and critical installation activities are being prepared. The current status, three years into the project, will be revealed, along with the expected performance of the accelerator and the technical challenges involved. This paper will focus on the implementation of the project.  
slides icon Slides THXGBD3 [13.552 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THXGBD3  
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THXGBF2 Beam Commissioning of the IFMIF EVEDA Very High Power RFQ rfq, cavity, MMI, operation 2902
 
  • E. Fagotti, L. Antoniazzi, L. Bellan, D. Bortolato, M. Comunian, A. Facco, M.G. Giacchini, F. Grespan, M. Montis, A. Palmieri, A. Pisent, F. Scantamburlo
    INFN/LNL, Legnaro (PD), Italy
  • B. Bolzon, N. Chauvin, R. Gobin
    CEA/IRFU, Gif-sur-Yvette, France
  • P. Cara
    IFMIF/EVEDA, Rokkasho, Japan
  • H. Dzitko, D. Gex, A. Jokinen, G. Phillips
    F4E, Germany
  • T. Ebisawa, A. Kasugai, K. Kondo, K. Sakamoto, T. Shinya, M. Sugimoto
    QST, Aomori, Japan
  • R. Heidinger, A. Marqueta, I. Moya
    Fusion for Energy, Garching, Germany
  • P. Mereu
    INFN-Torino, Torino, Italy
  • G. Pruneri
    Consorzio RFX, Associazione Euratom-ENEA sulla Fusione, Padova, Italy
  • M. Weber
    CIEMAT, Madrid, Spain
 
  IFMIF, the International Fusion Materials Irradiation Facility, is an accelerator-based neutron source that will use Li(d, xn) reactions to generate a flux of neutrons with a broad peak at 14 MeV equivalent to the conditions of the Deuterium-Tritium reactions in a fusion power plant. IFMIF is conceived for fusion materials testing. The IFMIF prototype linear accelerator (LIPAc) is jointly developed by Europe and Japan within the IFMIF EVEDA project: it is composed of an ion source, a LEBT, an RFQ, a MEBT and a SC linac, with a final energy of 9 MeV. The 4-vane Radio Frequency Quadrupole (RFQ), developed by INFN in Italy, will accelerate a 130 mA deuteron beam from 0.1 to 5 MeV in continuous wave, for a beam power of 650 kW. The 9.8 m long 175 MHz cavity is composed of 18 x 0.54 m long modules flanged together and aligned within 0.3 mm tolerance. The RFQ was completed, delivered and assembled at the Rokkasho site and is presently under extended RF tests. The second phase of beam commissioning (up to 2.5 MeV/u) was scheduled to start at the end of 2017. Several unexpected issues and incidents significantly delayed the original program, which is however proceeding step by step toward the full achievement of its goals.  
slides icon Slides THXGBF2 [5.323 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THXGBF2  
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THPAF026 Modeling Studies for Synchrotron-Radiation-Induced Electron Production in the Vacuum Chamber Walls at CesrTA photon, electron, simulation, site 3011
 
  • S. Poprocki, J.A. Crittenden, D. L. Rubin, D. Sagan
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467 and the US Department of Energy DE-FC02-08ER41538, DE-SC0006505.
We report on calculations of electron production by synchrotron radiation absorbed in the vacuum chamber walls of the Cornell Electron Storage Ring (CESR). These electrons are the source of electron clouds which limit the performance of storage rings by causing betatron tune shifts, instabilities and emittance growth. Until now, cloud buildup modeling codes have used ad hoc models of the production of the seed electrons. We have employed the photon scattering code Synrad3D to quantify the pattern of absorbed photons around the CESR ring, including the transverse distribution on the wall of the beam-pipe. These distributions in absorbed photon energy and incident angle are used as input to Geant4-based simulations of electron emission from the walls. The average quantum efficiency is found to vary dramatically with the location of the absorption site, owing to the distribution in impact energies and angles. The electron production energy spectrum plays an important role in the modeling of electron cloud buildup, where the interplay of production energy and acceleration by the beam bunches determines the time structure and multipacting characteristics of the cloud.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF026  
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THPAF036 Longitudinal and Quadrupolar Coupling Impedance of an Elliptical Vacuum Chamber With Finite Conductivity in Terms of Mathieu Functions impedance, coupling, factory, electromagnetic-fields 3040
 
  • M. Migliorati, L. Palumbo
    Sapienza University of Rome, Rome, Italy
  • N. Biancacci
    CERN, Geneva, Switzerland
  • M. Migliorati, L. Palumbo
    INFN-Roma1, Rome, Italy
  • V.G. Vaccaro
    Naples University Federico II and INFN, Napoli, Italy
 
  Funding: Work supported by the CERN PS-LIU project
The resistive wall impedance of an elliptical vacuum chamber in the classical regime with infinite thickness is known analytically for ultra-relativistic beams by means of the Yokoya form factors. Starting from the longitudinal electric field of a point charge moving at arbitrary speed in an elliptical vacuum chamber, which we express in terms of Mathieu functions, in this paper we take into account the finite conductivity of the beam pipe walls and evaluate the longitudinal and quadrupolar impedance for any beam velocity. We also obtain that the quadrupolar impedance of a circular pipe is different from zero, approaching zero only for ultra-relativistic particles. Even if some of the results, in particular in the ultra-relativistic limit, are already known and expressed in terms of form factors, this approach is the first step towards the calculation of the general problem of a multi-layer vacuum chamber with different conductivities and of elliptic cross section.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF036  
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THPAF052 Impedance Analysis of New PS Internal Dump Design impedance, HOM, coupling, resonance 3083
 
  • B.K. Popovic, L. Teofili, C. Vollinger
    CERN, Geneva, Switzerland
 
  The High Luminosity Large Hadron Collider (HL-LHC) project at CERN calls for increasing beam intensity in the injector chain. In the Proton Synchrotron (PS), a pre-injector of the LHC, these intensities can result in beam instabilities and potential RF heating of machine components, such that impedance mitigation measures are required. To study these intensity effects, the PS impedance model has been developed and is continuously updated. Each new machine element that is to be added into the accelerator requires an impedance study to minimize its contribution with respect to the machine's overall impedance budget. In such a context, this paper presents the impedance analysis of the new design of the internal beam dump for the PS, showing the design process required to reduce the impedance contribution of this element. Furthermore, the impedance analysis of the currently installed beam dump is analysed in order to compare the impedance contributions of the two designs.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF052  
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THPAK001 Impedance Evaluation of In-Vacuum Undulator at KEK Photon Factory impedance, simulation, undulator, factory 3200
 
  • O. Tanaka, M. Adachi, R. Kato, N. Nakamura, T. Obina, S. Sakanaka, R. Takai, K. Tsuchiya, N. Yamamoto
    KEK, Ibaraki, Japan
 
  The estimate of impedance and kick factors of the recently installed at KEK Photon Factory (PF) four In-Vacuum Undulators (IVU) is currently a very important issue, because they could be considerable contributors to the total impedance of PF. Moreover, the coupling impedance of the IVUs could lead to the beam energy loss, changes in the bunch shape, betatron tune shifts and, finally, to the various beam instabilities. Using the simulation tool (CST Particle Studio), longitudinal and transverse impedances of the IVUs were evaluated and compared to analytical formulas and measurement results. The study provides guidelines for mitigation of unwanted impedance, for the accurate estimate of its effects on the beam quality and beam instabilities and also for the impedance budget of a newly designed next-generation machine which has many IVUs and small-aperture beam pipes.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK001  
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THPAK005 Measuring the Coupling Impedance of Vacuum Components for the Advanced Photon Source Upgrade Using a Goubau Line impedance, cavity, simulation, coupling 3211
 
  • M.P. Sangroula
    IIT, Chicago, Illinois, USA
  • R.M. Lill, R.R. Lindberg, R.B. Zabel
    ANL, Argonne, Illinois, USA
 
  The Planned upgrade of the Advanced Photon Source to a multi-bend achromat (MBA) will increase the x-ray brightness by two to three orders of magnitude. Storing such an intense beam stably inside the narrow gap vacuum chambers requires sophisticated and appropriately designed rf-components that helps to minimize rf heating and collective instabilities associated with the impedance of these small-aperture vacuum components. As part of this effort, my research focuses on impedance measurement and simulation of various MBA vacuum components. In this paper, we briefly introduce the novel Goubau line (G-line) test fixture for the impedance measurement, at first, and then present our measurements data along with simulations with simulations for various vacuum components designed for the APS Upgrade.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK005  
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THPAK030 Studies of Longitudinal Dynamics in the Micro-Bunching Instability Using Machine Learning longitudinal-dynamics, bunching, synchrotron, simulation 3277
 
  • T. Boltz, M. Brosi, E. Bründermann, A.-S. Müller, P. Schönfeldt, M. Yan
    KIT, Karlsruhe, Germany
  • M. Schwarz
    CERN, Geneva, Switzerland
 
  The operation of synchrotron light sources with short electron bunches increases the emitted CSR power in the THz frequency range. However, the spatial compression leads to complex longitudinal dynamics, causing the formation of micro-structures in the longitudinal bunch profiles. The fast temporal variation and small scale of these micro-structures put challenging demands on their observation. At the KIT storage ring KARA (KArlsruhe Research Accelerator), diagnostics have been developed allowing direct observation of the dynamics by an electro-optical setup, and indirect observation by measuring the fluctuation of the emitted CSR. In this contribution, we present studies of the micro-structure dynamics on simulated data, obtained using the numerical Vlasov-Fokker-Planck solver Inovesa, and first applications on measured data. To deal with generated data sets in the order of terabytes in size, we apply the machine learning technique k-means to identify the dominant micro-structures in the longitudinal bunch profiles. Following this approach, new insights on the correlation of the CSR power fluctuation to the underlying longitudinal dynamics can be gained.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK030  
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THPAK046 The Ion-Hose Instability in High-Current Multi-Pulse Induction Linacs electron, simulation, induction, experiment 3320
 
  • C. Ekdahl
    LANL, Los Alamos, New Mexico, USA
 
  The ion-hose instability has long been considered a danger for long-pulse, high-current electron linear induction accelerators (LIAs)*. This instability is enabled by beam-electron ionization of residual background gas in the accelerator. The space-charge of the high-energy beam ejects low-energy electrons from the ionized channel, leaving a positively-charged ion channel that attracts the electron beam. The beam can oscillate in the potential well around the channel position. Likewise, the electron beam attracts the ions, which can oscillate about the beam position. Because of the vast differences in particle mass, the oscillations are out of phase, and the amplitudes grow unstably. The number of instability e-foldings is proportional to the channel ion density*, which in turn is proportional to the background pressure and pulse length. This scaling of the instability growth was demonstrated on the long-pulse DARHT-II linear induction accelerator (LIA) at Los Alamos**. The ion-hose instability is also problematic for high-current multi-pulse LIAs, because ion recombination times are so very long at typical background pressures. Moreover, because of low ion channel ion densities, and massive ions, channel expansion is too slow to reduce the instability growth by very much. In particular, the ion channel is expected to persist and its density to increase during the 3-microsecond duration of a four-pulse burst from the 2-kA, 20-MeV Scorpius LIA now being developed. Recent simulations with an experimentally validated code that was used to predict DARHT-II growth rates have shown that the magnetic focusing field designed for Scorpius will be strong enough to inhibit ion-hose instability if the background pressure is kept below a value that is readily attainable with the present designs of induction cells and other accelerator components. Details and results of these calculations are the subject of this presentation.
*H. L. Buchanan, Phys. Fluids, vol. 30, pp. 221 - 231, 1987
**C. A. Ekdahl, et al., IEEE Trans. Plasma Sci., vol. 34, pp. 460-466, 2006
 
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THPAK052 Single Bunch Instabilities in FCC-ee impedance, collider, simulation, electron 3336
 
  • E. Belli
    Sapienza University of Rome, Rome, Italy
  • G. Castorina, M. Migliorati
    INFN-Roma1, Rome, Italy
  • G. Rumolo
    CERN, Geneva, Switzerland
  • B. Spataro, M. Zobov
    INFN/LNF, Frascati (Roma), Italy
 
  FCC-ee is a high luminosity lepton collider with a centre-of-mass energy from 91 to 365 GeV. Due to the machine parameters and pipe dimensions, collective effects due to electromagnetic fields produced by the interaction of the beam with the vacuum chamber can be one of the main limitations to the machine performance. In this frame, an impedance model is required to analyze these instabilities and to find possible solutions for their mitigation. This paper will present the contributions of specific machine components to the total impedance budget and their effects on the beam stability. Single bunch instability thresholds will be estimated in both transverse and longitudinal planes.   
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK052  
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THPAK077 Feasibility of Non-Metal Vacuum Chamber for Storage Rings impedance, cavity, insertion-device, insertion 3411
 
  • T.-Y. Lee
    PAL, Pohang, Kyungbuk, Republic of Korea
 
  This paper studies if the vacuum chamber of an elec-tron storage ring can be made of dielectric non-meta materials such as ceramics or glass. The purpose of this study is to substantially reduce the broadband imped-ance of the vacuum chamber and consequently mitigate single bunch instabilities. This theoretical study examines how these materials can reduce the impedance and pro-poses how to resolve technical problems to occur.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK077  
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THPAK091 Design of the New Proton Synchrotron Booster Absorber Scraper (PSBAS) in the Framework of the Large Hadron Collider Injection Upgrade (LIU) Project impedance, proton, simulation, booster 3444
 
  • L. Teofili, M. Migliorati
    Sapienza University of Rome, Rome, Italy
  • J.A. Briz Monago, M. Calviani, N. Chritin, J.J. Esala, S.S. Gilardoni, I. Lamas Garcia, J. Maestre, T. Polzin, T.L. Rijoff
    CERN, Geneva, Switzerland
  • T.L. Rijoff
    TU Darmstadt, Darmstadt, Germany
 
  The Large Hadron Collider (LHC) Injector Upgrade (LIU)Project at CERN calls for increasing beam intensity for the LHC accelerator chain. Some machine components will not survive the new beam characteristics and need to be rebuilt for the new challenging scenario. This is particularly true for beam intercepting devices (BIDs) such as dumps, collimators, and absorber/scrapers, which are directly exposed to beam impacts. In this context, this work summarizes conceptual design studies on the new Proton Synchrotron Booster (PSB) Absorber/Scraper (PSBAS), a device aimed at cleaning the beam halo at the very early stage of the PSB acceleration. This paper outlines the steps performed to fulfil the component design requirements. It discusses thermo-mechanical effects as a consequence of the beam-matter collisions, simulated with the FLUKA Monte Carlo code and ANSYS finite element software; and the impedance minimization study performed to prevent beam instabilities and to reduce RF-heating on the device.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK091  
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THPAK103 Pragmatic Method of Deducing a Wake Function for a General 3D Structure impedance, wakefield, simulation, resonance 3469
 
  • G. Skripka
    CERN, Geneva, Switzerland
  • R. Nagaoka
    SOLEIL, Gif-sur-Yvette, France
 
  A key quantity in simulating collective beam instabilities is the wake potential of a bunch of particles whose charge distribution is continuously evolving in time. However, obtaining such wake potential is only possible if a wake excited by a single particle in the surrounding environment is known. A practical self-consistent approach was developed to obtain an effective wake function from a numerical wake potential computed for a finite length bunch. The wake potential is processed to a numerical impedance which is decomposed into a set of well-known analytical wake functions. The decomposed impedance is then transformed back into time domain and, thus, converted into an effective wake function which is by nature physical and most consistent with the numerical wake potential. Though the method is limited by the initial numerical impedance data and the choice of impedance decomposition, the retrieved wake function can be used in instability simulations with a bunch whose length is comparable to that used in the electromagnetic field solver. We show that the method can be applied to a general 3D structure, which allows finding effective wake functions of realistic vacuum chambers.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK103  
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THPAK107 Space-Charge Hamiltonian with a Space Coordinate as Independent Variable plasma, space-charge, TRIUMF, synchrotron 3484
 
  • T. Planche, P. M. Jung, S.D. Rädel
    TRIUMF, Vancouver, Canada
 
  We present a version of the Low Lagrangian tailored to treat space-charge effects in particle accelerators: the Lagrangian is relativistic and uses a space coordinate as the independent variable. From this Lagrangian we obtain the corresponding Hamiltonian. From the Hamiltonian we obtain equations of motion for the 8 canonical variables, which can be plugged into a symplectic numerical integrator. We will finally discuss the possibility of numerically solving this problem using an explicit symplectic integrator.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK107  
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THPAL016 Study of the Performances of a 3D Printed BPM HOM, impedance, instrumentation, status 3656
 
  • N. Delerue, D. Auguste, J. Bonis, F. Gauthier, A. Gonnin, S. Jenzer, O. Trofimiuk
    LAL, Orsay, France
  • A. Vion
    BV Proto, Sévenans, France
 
  Funding: Work supported by IN2P3 ‘‘3D Metal'' innovation program; Oleh Trofimiuk stay in France is supported by the IDEATE International Associated Laboratory (LIA) between France and Ukraine.
Following previous results which have shown that some components built using additive manufacturing (3D printing) are compatible with ultra high vacuum, we have adapted the design of a stripline BPM to the requirements of additive manufacturing and built it. We report here on the design adaptation and on its mechanical and electrical performances.
 
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THPAL040 Lossy Beam Pipe HOM Load Ceramics with DC Conductivity experiment, HOM, site, controls 3729
 
  • M.L. Neubauer, A. Dudas
    Muons, Inc, Illinois, USA
  • F. Marhauser
    JLab, Newport News, Virginia, USA
 
  The ceramic materials used in the beam pipe for super-conducting RF accelerators have the problem of charging due to the electron cloud and secondary electron emission. A novel solution is in the application of conductive nanoparticles to the lossy ceramic. The lossy ceramic is pre-processed to provide for pores that will accept the conductive nanoparticles and then coated with a thin film to prevent the nanoparticles from entering the environment. The same process was also done with sub-micron carbon particles. Measurements of surface conductivity with and without a vacuum compatible sealant are reported on along with microwave measurements.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL040  
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THPAL052 Finite Element Analysis on Beam-Induced Heat Load in in-Vacuum Undulators with a Small Magnet Gap undulator, simulation, synchrotron, synchrotron-radiation 3760
 
  • J.-C. Chang, Y.-H. Liu
    NSRRC, Hsinchu, Taiwan
 
  In-vacuum undulators with a small gap and short period have been applied in synchrotron accelerators for hard X-rays users for years. However, beam-induced heat load resulted from synchrotron radiation or the image current will not only degrade the performance of undulator but damage the magnet foil. It is difficult to quantitatively study heat transfer phenomenon of the magnet foil through physical experiment. In this study, finite element analysis was applied to study the effect of beam-induced heat load on an in-vacuum undulator.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL052  
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THPAL056 Vibration Measurements in the TPS Vacuum System radiation, synchrotron, storage-ring, synchrotron-radiation 3772
 
  • Y.C. Yang, C.K. Chan, C.-C. Chang, C.S. Chen, J. -Y. Chuang, Y.M. Hsiao, C.C. Liang, Y.Z. Lin
    NSRRC, Hsinchu, Taiwan
 
  The Taiwan Photon Source (TPS) is currently operated in top-up mode for users. In order to improve the stability of the synchrotron light source, vibrations related to the vacuum system have been investigated and improved by turning off pumping systems and reducing the flow rate in chamber cooling water circuits. In this paper, vibrations in different vacuum chambers with normal cooling water condition were investigated, their sources were recorded and clarified and properties of different materials for water tubes were also compared.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL056  
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THPAL057 Development of the Aluminum Beam Duct for the Ultra-Low Emittance Light Source experiment, storage-ring, impedance, emittance 3775
 
  • G.-Y. Hsiung, J.-R. Chen, C.M. Cheng, S-N. Hsu, H.P. Hsueh, Y.C. Yang
    NSRRC, Hsinchu, Taiwan
  • J.-R. Chen
    National Tsing Hua University, Hsinchu, Taiwan
 
  The future light source with ultra-low emittance, typically < 500 pm rad, requests the beam duct with inner aperture < 20 mm for the electron storage ring. Besides, the cross section of the beam duct must be kept smooth for lowering the impedance. The aluminum extruded beam duct of 10 mm inside and 1 ~ 2 m in length was developed for this purpose. The beam duct was machined in ethanol to obtain a clean surface for a lower thermal outgassing rate. To mitigate the impedance of the flange connection, a special designed diamond-edge gasket and the aluminum flange without knife edge were developed. The inner diameters of both flange and gasket, 10 mm, are the same as that of beam duct. The sealing of the gasket has been proved leak-tight. The ultimate pressure and the thermal outgassing rate of the beam duct has achieved < 2.0·10-10 Torr and < 1.4·10-13 Torr l/(s cm2), respectively after baking. Those results fulfill both the ultrahigh vacuum and lowest impedance are applicable for the next generation ultra-low emittance light source.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL057  
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THPAL058 Effect of Ozonated Water Cleaning on Photon Stimulated Desorption in a Stainless Steel Chamber photon, ECR, experiment, radiation 3778
 
  • C.M. Cheng, C.K. Chan, C.-C. Chang, Y.T. Cheng, J. -Y. Chuang, G.-Y. Hsiung, L.H. Wu, Y.C. Yang
    NSRRC, Hsinchu, Taiwan
 
  Aluminium vacuum chambers cleaned with ozonated water show a reduction of residual carbon and lower surface outgassing rate after baking. We would like to investigate if stainless steel chambers show similar ef-fects. A stainless steel test chamber was cleaned by stand-ard chemical cleaning only and then compared with an-other one after immersion in 30ppm ozonated water for thirty minutes. Both samples were baked, then photon exposed and the photon desorption yields were deter-mined by vacuum gauges and residual gas analysers at the TLS 19B beamline. The test results on photon stimulated desorption yields and partial pressure variations with and without ozonated water cleaning of the stainless steel tubes will be discussed in some detail.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL058  
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THPAL063 RF and Thermo-Mechanical Considerations in Designing the Waveguide Iris Coupler for the Drift Tube Linac in the ORNL Spallation Neutron Source cavity, GUI, DTL, simulation 3796
 
  • S.W. Lee, Y.W. Kang
    ORNL, Oak Ridge, Tennessee, USA
 
  Funding: This work was supported by SNS through UT Battelle, LLC, under contract DE AC05 00OR22725 for the U.S.DOE
The Spallation Neutron Source (SNS) employs tapered ridge waveguide iris couplers to power six drift tube linac (DTL) cavity structures with pulsed RF systems using 2.5MW klystrons at 402.5MHz. All DTL iris couplers have been operating continuously for more than a decade without replacement. Transferring high RF energy to the cavities requires robust RF and mechanical performances with respect to power dissipation, electrical breakdown, and vacuum pressure. Considering the upcoming full 1.4MW operation and the future proton power upgrade (PPU) project, the structural design and the material selection needed to be reviewed for potential spare manufacturing. The existing design and the modified design with improvements to the coupler have been numerically studied. For the study, 3D models were used for RF and structural characterizations of the waveguide iris couplers on the DTL cavity. RF and thermo-mechanical co-simulations were performed to assess the effects of using the different materials and the structural modification.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL063  
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THPAL069 Simulation of a 10 mm Diameter Cascaded Plasma Window plasma, cathode, simulation, experiment 3812
 
  • P.P. Gan, S. Huang, Y.R. Lu, S.Z. Wang, K. Zhu
    PKU, Beijing, People's Republic of China
 
  As a windowless vacuum device, the 10 mm diameter 60 mm long plasma window designed by Peking University only achieved to separate 28.8 kPa from 360 Pa experimentally with 50 A direct current and 2.5 kW power. Based on our 10 mm diameter plasma window, we have proposed a cascaded plasma window to achieve the isolation of atmosphere and high vacuum. In this paper, a numerical 2D FLUENT-based magneto-hydrodynamic simulation on 10 mm diameter cascaded plasma window was developed. The gas inlet, arc creation and plasma expansion segments are all contained in this model. A set of parameters including pressure, temperature, velocity and current distribution were obtained and analysed. In our first simulation, the isolation of 100 kPa and 50 Pa pressure has been realised, and some interesting phenomena occurred.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL069  
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THPAL076 Experimental Methods for the Assessment of NEG Pumps Working in Dust-Sensitive Environments cavity, SRF, experiment, background 3828
 
  • T. Porcelli, E. Maccallini, P. Manini, M. Mura, M.F. Urbano
    SAES Getters S.p.A., Lainate, Italy
 
  NEG pumps have been widely adopted by many accelerator facilities since decades. However, their use in dust-sensitive areas - such as superconductive radio frequency (SRF) cavities - has always been limited by concerns about accidental dust emission, which could induce detrimental field emission. As future machines will necessarily rely on highly-efficient SRF cavities, able to supply very high accelerating gradients, requirements in terms of particle release from vacuum components (e.g., pumps and valves) are becoming more and more stringent. At the same time, achieving stable ultra-high vacuum conditions is crucial, as condensed residual gas might also be a potential source of field emission. At present, a unified standard procedure to assess dust generation and propagation along a machine is still missing and discussions are ongoing in the vacuum community. Recent experimental measurements demonstrated the compatibility of sintered NEG pumps with ultra-clean environments, due to their intrinsic very low dust release. In parallel, in-situ tests performed at different accelerator facilities showed absence of dust contamination from NEGs and no impact on cavities efficiency.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL076  
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THPAL078 In-Vacuum Lambertson Septum for SPEAR3 Low Emittance Injection septum, simulation, storage-ring, injection 3831
 
  • M.A.G. Johansson, J. Langton, J.A. Safranek
    SLAC, Menlo Park, California, USA
  • S.C. Gottschalk
    STI Magnetics LLC, Woodinville, USA
 
  Funding: Work supported by DOE Contract No. DE-AC02-76SF00515
A new in-vacuum Lambertson septum magnet is being designed for the SPEAR3 storage ring, intended to replace the existing septum to allow injection into a new lower emittance operation mode for SPEAR3. The new septum design is constrained to fit in the same length and have the same bend angle as the existing injection septum, so as to minimize changes to surrounding storage ring and transfer line components, while also meeting stringent requirements on the stored beam leakage field. This has led to a design using Vanadium Permendur alloy for the septum pole pieces, with shaping of the inner profile of the stored beam channel to minimize the leakage fields indicated in 2D and 3D magnetic simulations.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL078  
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THPAL085 High Power RF Conditioning on CLARA cavity, linac, solenoid, multipactoring 3852
 
  • L.S. Cowie, D.J. Scott
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • G. Burt, W.L. Millar
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
 
  The CLARA accelerator at Daresbury Laboratory will have 8 normal conducting RF cavities. Automating the high power RF conditioning of these cavities will mean a repeatable, research-lead process is followed. An auto-mated algorithm has been written in Python. A prototype algorithm was used to condition the first CLARA travel-ling wave linac in October 2017. The linac was success-fully conditioned over approximately 12 million pulses up to 27 MW for a 750 ns pulse. A more complex and robust algorithm was used to re-condition the standing wave 10 Hz photoinjector after a cathode change. The photoinjec-tor was conditioned to 10 MW for a 2.5 μs pulse in Feb-ruary 2018 over 2.1 million pulses. Conditioning method; differences for travelling and standing wave structures; difficulties and interesting phenomena are all discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL085  
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THPAL086 Superconducting Thin Film RF Measurements cavity, SRF, niobium, operation 3856
 
  • P. Goudket, L. Bizel-Bizellot, L. Gurran, O.B. Malyshev, S.M. Pattalwar, R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • G. Burt, L. Gurran
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • P. Goudket, T. Junginger, O.B. Malyshev, S.M. Pattalwar, R. Valizadeh
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • L. Gurran, T. Junginger
    Lancaster University, Lancaster, United Kingdom
 
  As part of an ongoing programme of SRF Thin Films development, a radiofrequency (RF) cavity and cryostat dedicated to the measurement of superconducting coatings at GHz frequencies was designed to evaluate surface resistive losses on a flat sample. The resonator has now been used for measurements on Thin Film samples. Results from a test on a sample previously tested at Cornell University are presented. In order to simplify the measurements and achieve a faster turnaround, the experiment will be moved to a new cryostat fitted with a cryocooler. This will limit the measurements to low power only, but will allow a much faster sorting of samples to identify those that would benefit from further investigation. A description of the system and initial results will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL086  
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THPAL092 Test Particle Monte Carlo Simulation of NEG Coated Narrow Tubular Samples ECR, experiment, simulation, SRF 3862
 
  • O. Seify, A.N. Hannah, O.B. Malyshev, Sirvinskaite, R. Sirvinskaite, R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • Sirvinskaite, R. Sirvinskaite
    Loughborough University, Loughborough, Leicestershire, United Kingdom
 
  The pumping properties of the NEG coated vacuum chambers play an important role in the efficiency of vac-uum system of accelerators. The sticking probability of the NEG films is one the most important parameters to characterise the pumping properties of the NEG coated vacuum chambers. In order to investigate the NEG film sticking probability, Test Particle Monte-Carlo (TPMC) models were used. The models were based on the design of the installed experimental setup in ASTeC Vacuum Science group laboratory at Daresbury Laboratory (DL). The results of the simulations have been used for inter-preting the results of the measurements in the experi-mental setup.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL092  
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THPAL098 Pumping Properties of Single Metal Zirconium Non-Evaporable Getter Coating target, site, experiment, injection 3869
 
  • Sirvinskaite, R. Sirvinskaite, M.D. Cropper, M.D. Cropper
    Loughborough University, Loughborough, Leicestershire, United Kingdom
  • A.N. Hannah, O.B. Malyshev, R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • O.B. Malyshev, R. Valizadeh
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
 
  Non-evaporable getter (NEG) coating has been used for years in many particle accelerator facilities due to its evenly distributed pumping speed, low thermal outgassing, and low photon and electron stimulated desorption yields. We have previously demonstrated that quaternary Ti-Zr-Hf-V coating deposited from an alloy wire has the lowest desorption yields, the highest sticking probability and sorption capacity. In this work, we explore the single element targets which are widely available and can be produced in a form of a wire that is easy to apply for a uniform coating of various shapes of vacuum chamber. Single metal Zr coatings have been tested to find a more efficient and cheaper way of producing the NEG-coated vacuum chambers. Two samples coated with Zr of dense and columnar structure were analysed and results of the pumping properties are reported. The results show that pure Zr coating could be an economic solution, despite not being as effective as can be achieved with quaternary NEG film. It shows that columnar Zr coating can be activated and reaches full pumping capacity at 160°C. This is close to the activation temperature of Ti-Zr-Hf-V and lower than that for the widely used ternary Ti-Zr-V alloy.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL098  
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THPAL104 The Magnetic Field Measurement Systems for a Cryogenic Undulator and a Superconducting Undulator at SSRF cryogenics, SRF, undulator, GUI 3878
 
  • H.F. Wang
    SSRF, Shanghai, People's Republic of China
  • M.F. Qian, W. Zhang, Q.G. Zhou
    SINAP, Shanghai, People's Republic of China
 
  Two cryogenic permanent magnet undulators (CPMU) have been developed and assembled into storage ring at SSRF,in order to reach larger magnetic field and to produce higher brilliance in the hard X rays domain. Lowering the temperature of permanent magnets increases the magnetic produced field about by 15%. A set of magnetic measurement system and a suitable magnetic field optimization method have been developed. The design of a magnetic measurement bench based on a Hall probe to perform low temperature measurement has been finished. In addition, a 50-period superconducting undulator prototype with 16mm period length is also being developed for more photons with some specific photon characteristic. And a special hall probe system has been built in order to characterize the magnetic field distribution of the SCU prototype.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL104  
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THPAL106 Heating Unit Controller at NSRC SOLARIS TANGO, controls, undulator, PLC 3885
 
  • W.T. Kitka, P. Bulira, P. Czernecki, M.K. Fa'owski, K. Kubal, P. Kurdziel, A.M. Marendziak, M.P. Nowak, M. Ostoja-Gajewski, M. Rozwadowski, K. Wawrzyniak, Z. Zbylut
    Solaris National Synchrotron Radiation Centre, Jagiellonian University, Kraków, Poland
 
  Solaris is a third generation light source constructed at the Jagiellonian University in Kraków, Poland. The machine was designed by the MAX IV Laboratory team. Commissioning of the machine was accomplished at 2016 April and now synchrotron operate in decay mode. Two beamlines PEEM/XAS and UARPES were installed and now are being commissioned. Three more PHELIX, XMCD and diagnostic beamline have received funding and it will be installed and commissioned in range of next few years. The SOLARIS Heating Unit Controller (HUC) was designed to perform bake-out process of new installed vacuum systems. It will allow to perform activation process of undulator vacuum chamber inner coated with NEG layer and also activation process of NEG strips installed in dipole vacuum chambers. HUC is able to control independently up to six 2 kW temperature channels and two current channels. System was built based on Allen-Bradley PLC and Tango Controls. Easy access to the device is provided by the GUI design based on Taurus framework.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL106  
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THPAL107 Three Years of Operational Experience With the Solaris Vacuum System storage-ring, electron, MMI, synchrotron 3888
 
  • A.M. Marendziak, M. Rozwadowski, T. Sobol, M.J. Stankiewicz, A.I. Wawrzyniak
    Solaris National Synchrotron Radiation Centre, Jagiellonian University, Kraków, Poland
 
  Solaris, a 1.5 GeV third generation synchrotron light source, was commissioned in 2016 April and is currently operated in decay mode. Two beamlines PEEM/XAS and UARPES were installed and now are being commis-sioned. Three more PHELIX, XMCD and diagnostic beamlines have received funding and will be installed and commissioned in next few years. With total accumu-lated beam dose near to 690 A.h and three orders of mag-nitude reduction of outgassing the design goal of 500 mA beam current and electron energy of 1.5 GeV has been achieved. As the beam current was increased, a few vacu-um problems were encountered, including vacuum leaks in RF and arc sectors and unexpected pressure bursts near photon absorbers. Lessons learned and operational expe-rience will be presented and discussed in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL107  
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THPAL110 High-Power RF Test of Coaxial Couplers for the Injection Linac of XiPAF cavity, multipactoring, coupling, linac 3899
 
  • Y. Lei, X. Guan, R. Tang, X.W. Wang, Q.Z. Xing, H.Y. Zhang, S.X. Zheng
    TUB, Beijing, People's Republic of China
  • J. Jiang, H. Li, C. Yu
    Beijing Aerospace Guagntong Technology Co., Beijing, People's Republic of China
 
  For the high-power RF test of the coaxial couplers which will be employed on the linac injector of the XiPAF (Xi'an Proton Application Facility) project, a high-power conditioning cavity was designed and manufactured [1]. There are some optimized aspects on the cavity and couplers to obtain better RF performance during the high-power testing process. The traveling-wave test and full-power-reflection test were executed to check whether the coupler can afford the enough power level for the linac operation, and whether only one coupler can afford the total power for the RFQ. The construction of the testing stand, optimization of RF parameters and results of high-power RF test are presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL110  
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THPAL114 The Analytical Model of the Helical Accelerating Structure of Linac with Helix Outside of the Vacuum Chamber experiment, simulation, resonance, TRIUMF 3908
 
  • N.V. Avreline
    TRIUMF, Vancouver, Canada
 
  An analytical model of the helical RF resonator for the single charged 250 keV nitrogen ion implanter operating in CW was developed. The analytical model allowed to determine the geometry of the accelerating structure and to construct CST Microwave Studio and ANSYS HFSS models based on this analytical model. Results obtained from the analytical model and simulations were within 5% of each other. The experimental investigation of the accelerating section confirmed that the models are correct. The accelerating section was tuned and verified for the right accelerating field distribution and operating frequency. Finally, the section was successfully tested in 2 kW CW RF power.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL114  
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THPAL126 Nitrogen Bake-out Procedures at the Vertical High-Temperature UHV-Furnace of the S-DALINAC cavity, SRF, niobium, linac 3937
 
  • R. Grewe, L. Alff, M. Arnold, J. Conrad, S. Flege, M. Major, N. Pietralla
    TU Darmstadt, Darmstadt, Germany
  • F. Hug
    IKP, Mainz, Germany
 
  Funding: Work supported by the Federal Ministry of Education and Research through grant No. 05H15RDRBA.
As the performance limits of bulk Nb srf cavities are reached, our research is focused on materials with superior srf properties like Nb3Sn and NbN. Research on NbN resulted in the "nitrogen-doping" process used for increasing the quality factors of srf cavities for the LCLS-II project. This process leads to delta-phase Nb-N, a phase with higher critical sc parameters than bulk Nb. This phase is formed at temperatures of 800°C in nitrogen atmospheres of 10-2 mbar. Other crystalline phases of NbN have even better sc parameters. We concentrate our research on applicability of delta-phase NbN for cavities. The delta-phase forms at temperatures of above 1300°C, which is more than most of the furnaces at accelerator facilites are capable of. Since 2005 the Institute for Nuclear Physics at the Technische Universität Darmstadt operates a high temperature vacuum furnace which has been upgraded to allow temperatures of up to 1750°C and bakeouts of niobium samples and cavities in nitrogen atmospheres. We will report on the current status of our research on nitrogen bake-out procedures on Nb samples. The samples have been analyzed at the Material Science Departement with SIMS, REM and XRD.
 
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THPAL127 Structural Investigations of Nitrogen-Doped Niobium for Superconducting RF Cavities niobium, cavity, ECR, experiment 3940
 
  • M. Major, L. Alff, M. Arnold, J. Conrad, S. Flege, R. Grewe, M. Mahr, N. Pietralla
    TU Darmstadt, Darmstadt, Germany
  • F. Hug
    KPH, Mainz, Germany
 
  Funding: Work supported by the German Federal Ministry for Education and Research (BMBF) through grant 05H15RDRBA.
Niobium is the standard material for superconducting RF (SRF) cavities. Superconducting materials with higher critical temperature or higher critical magnetic field allow cavities to work at higher operating temperatures or higher accelerating fields, respectively. Enhancing the surface properties of the superconducting material in the range of the penetration depth is also beneficial. One direction of search for new materials with better properties is the modification of bulk niobium by nitrogen doping. In the Nb-N phase diagram the cubic delta-phase of NbN has the highest critical temperature (16 K). Already slight nitrogen doping of the alpha-Nb phase results in higher quality factors.* Nb samples were N-doped at the refurbished UHV furnace at IKP Darmstadt. Reference samples were annealed in 1 bar nitrogen atmosphere at different temperatures. In this contribution the results on the structural investigations (x-ray diffraction and pole figure, secondary ion mass spectroscopy, scanning electron microscopy) at the Materials Research Department of TU Darmstadt will be presented.
*Grassellino et al., Proc. SRF2015, MOBA06, 48.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL127  
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THPAL128 Autonomous Topography Detection and Traversal for an Inspection Robot Within the Beamline of Particle Accelerators experiment, FEL, kicker, heavy-ion 3943
 
  • N. Schweizer
    Technische Universität Darmstadt (TU Darmstadt, RMR), Darmstadt, Germany
  • I. Pongrac
    GSI, Darmstadt, Germany
 
  Particle accelerators feature ultra-high vacuum pipe systems with unique topography, i.e. with a multitude of different vacuum chambers of varying dimensions and varying pipe apertures. In order to be able to examine the interior of the entire vacuum system, even those parts which are not accessible without disassembling large parts of the accelerator, a semi-autonomous robot is being developed which shall traverse and visually inspect the vacuum system of particle accelerators. We present a generic concept based on distance sensors for the inspection robot to detect steps between vacuum chambers and gaps in the beamline. Movement strategies to autonomously overcome these basic obstacles are introduced. For evaluation we use simulations of ideal environments with flat surfaces as well as realistic beam pipe environments of the SIS100 particle accelerator. Additionally, a prototype of our robot concept confirms the implementation of all maneuvers. Results show that obstacles of previously unknown dimensions can be detected and reliably traversed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL128  
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THPAL133 LASE Surfaces for Mitigation of Electron Cloud in Accelerators electron, laser, cavity, experiment 3958
 
  • B.S. Sian
    UMAN, Manchester, United Kingdom
  • O.B. Malyshev, R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
 
  Vacuum chamber surface characteristics such as the photon and secondary electron yields (PEY and SEY) are critical parameters in the formation of an electron cloud, a serious problem that limits the performance of proton and positron accelerators. A few years ago it was discovered by the Vacuum Solutions Group at Daresbury laboratory that Laser Ablation Surface Engineering (LASE) could provide surfaces with SEY<1 [1,2]. The LASE surfaces are considered as a baseline solution for electron cloud miti-gation in the Future Circular Collider (FCC). However, these surfaces are undergoing further optimisation for the FCC application. While keeping SEY<1 the surfaces should meet the following criteria: Low outgassing, Low particulate generation and low surface resistance. In this paper we will report a number of new surfaces created using the LASE technique with different laser parameters (wavelength, scan speed, pitch, repetition rate, power, and pulse length) and their effect on the SEY, surface re-sistance and vacuum properties, etc  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL133  
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THPAL150 Development of Tsinghua X-Band High Power Test Facility klystron, controls, GUI, software 3999
 
  • M.M. Peng, D.Z. Cao, W. Gai, Y.L. Jiang, J. Liu, J. Shi, P. Wang
    TUB, Beijing, People's Republic of China
 
  The X band high power test facility consists of a 11.424 GHz, 50 MW CPI klystron and a ScandiNova pulse modulator at Tsinghua University has been built since Sept 2017 and the output RF power has reached 60 MW with 200 ns pulse width at a repetition frequency of 10. The klystron output RF pulse will eventually be 50 MW at a 1.5 μs. A group of cylinder pulse compressor will be installed. High gradient accelerating structures for research and TTX will be tested on this facility.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL150  
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THPMF015 Lifetime and Beam Losses Studies of Partially Strip Ions in the SPS (129Xe39+) injection, factory, beam-losses, electron 4070
 
  • S. Hirlaender, R. Alemany-Fernández, H. Bartosik, N. Biancacci, T. Bohl, S. Cettour Cave, K. Cornelis, B. Goddard, V. Kain, M.W. Krasny, M. Lamont, D. Manglunki, G. Papotti, M. Schaumann, F. Zimmermann
    CERN, Geneva, Switzerland
  • K. Kroeger
    FSU Jena, Jena, Germany
  • V.P. Shevelko
    LPI RAS, Moscow, Russia
  • T. Stöhlker, G. Weber
    IOQ, Jena, Germany
 
  The CERN multipurpose Gamma Factory proposal relies on using Partially Stripped Ion (PSI) beams, instead of electron beams, as the drivers of its light source. If such beams could be successfully stored in the LHC ring, fluxes of the order of 1017 photons/s, in the gamma-ray energy domain between 1 MeV and 400 MeV could be achieved. This energy domain is out of reach for the FEL-based light sources as long as the multi TeV electron beams are not available. The CERN Gamma Factory proposal has the potential of increasing by 7 orders of magnitude the intensity limits of the present Inverse Compton Scattering sources. In 2017 the CERN accelerator complex demonstrated its flexibility by producing a new, xenon, ion beam. The Gamma Factory study group, based on this achievement, requested special studies. Its aim was to inject and to accelerate, in the SPS, partially stripped xenon ions Xe39+ measure their life time, and determine the relative strength of the processes responsible for the PSI beam losses. This study, the results of which are presented in this contribution, was an initial step in view of the the future studies programmed for 2018 with lead PSI beams.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF015  
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THPMF022 Study of Possible Beam Losses After Post-Linac Collimation at European XFEL undulator, radiation, FEL, simulation 4092
 
  • S. Liu, W. Decking
    DESY, Hamburg, Germany
  • F. Wolff-Fabris
    XFEL. EU, Schenefeld, Germany
 
  The European XFEL has been operating with the undulator beam line SASE1 and SASE3 since April 2017 and February 2018, respectively. Despite of the fact that the post-linac collimation has collimated the beam halo to ~20 σ level*, relative high radiation doses have been measured especially in the diagnostic undulator (DU) section**. In order to find the sources of beam losses after post-linac collimation, BDSIM simulations have been performed. In this paper, we will first present the possible losses generated by the wire scanners upstream of the undulators during a scan. The simulation results will be compared with the measured doses along SASE1 and SASE3 undulators. Based on the simulation results, we will estimate the frequency for wire scanner opera-tions. Besides, the simulations with large extension of beam halo hitting the vacuum chamber aperture transition will also be presented. Finally, other possible radiation dose sources will be discussed.
* S. Liu et al., in Proc. of FEL 2017, Santa-Fe, USA, Aug. 2017, paper TUP003.
** F. Wolff-Fabris et al.,IPAC-2018 contribution.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF022  
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THPMF031 In-Vacuum APPLE II Undulator undulator, cryogenics, operation, FEL 4114
 
  • J. Bahrdt, W. Frentrup, S. Grimmer, C. Kuhn, C. Rethfeldt, M. Scheer, B. Schulz
    HZB, Berlin, Germany
 
  APPLE II undulators are widely used in many synchrotron radiation facilities for the generation of arbitrarily polarized light, because they provide the highest magnet fields among all planar variably polarizing permanent magnet undulators (PMUs). So far, in-vacuum permanent magnet undulators (IVUs) have a fixed polarization, either planar or elliptical / helical. A variably polarizing in-vacuum undulator was never built due to the engineering challenges. We present the design of a new in-vacuum APPLE II, which will extend the photon energy range to tender X-rays in the 1.7 GeV storage ring BESSY II.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF031  
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THPMF034 Status Report of the Berlin Energy Recovery Linac Project BERLinPro gun, SRF, cathode, cavity 4127
 
  • M. Abo-Bakr, W. Anders, Y. Bergmann, K.B. Bürkmann-Gehrlein, A.B. Büchel, P. Echevarria, A. Frahm, H.-W. Glock, F. Glöckner, F. Göbel, B.D.S. Hall, S. Heling, H.-G. Hoberg, A. Jankowiak, C. Kalus, T. Kamps, G. Klemz, J. Knobloch, J. Kolbe, G. Kourkafas, J. Kühn, B.C. Kuske, J. Kuszynski, A.N. Matveenko, M. McAteer, A. Meseck, R. Müller, A. Neumann, N. Ohm, K. Ott, E. Panofski, F. Pflocksch, L. Pichl, J. Rahn, M.A.H. Schmeißer, O. Schüler, M. Schuster, J. Ullrich, A. Ushakov, J. Völker
    HZB, Berlin, Germany
  • A. Bundels
    Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Berlin, Germany
 
  Funding: Work supported by the German Bundesministerium für Bildung und Forschung, Land Berlin and grants of Helmholtz Association
The Helmholtz-Zentrum Berlin is constructing the Energy Recovery Linac Prototype BERLinPro, a demonstration facility for the science and technology of ERLs for future light source applications. BERLinPro is designed to accelerate a high current (100 mA, 50 MeV), high brilliance (norm. emittance below 1 mm mrad) cw electron beam. We report on the last year's progress, including the comissioning of the gun module as the first SRF component to be installed in BERLinPro.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF034  
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THPMF036 Status of the Conceptual Design of ALS-U lattice, emittance, kicker, cavity 4134
 
  • C. Steier, A.P. Allézy, A. Anders, K.M. Baptiste, E.S. Buice, K. Chow, G.D. Cutler, S. De Santis, R.J. Donahue, D. Filippetto, J.P. Harkins, T. Hellert, M.J. Johnson, J.-Y. Jung, S.C. Leemann, D. Leitner, M. Leitner, T.H. Luo, H. Nishimura, T. Oliver, O. Omolayo, J.R. Osborn, G.C. Pappas, S. Persichelli, M. Placidi, G.J. Portmann, S. Reyes, D. Robin, F. Sannibale, C. Sun, C.A. Swenson, M. Venturini, S.P. Virostek, W.L. Waldron, E.J. Wallén
    LBNL, Berkeley, California, USA
 
  Funding: This work was supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
The ALS-U conceptual design promises to deliver diffraction limited performance in the soft x-ray range by lowering the horizontal emittance to about 70 pm rad resulting in two orders of brightness increase for soft x-rays compared to the current ALS. The design utilizes a nine bend achromat lattice, with reverse bending magnets and on-axis swap-out injection utilizing an accumulator ring. This paper shows some aspects of the completed conceptual design of the accelerator, as well as some results of the R&D program that has been ongoing for the last years.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF036  
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THPMF038 Status of the BESSY VSR Project cavity, operation, SRF, electron 4138
 
  • P. Schnizer, W. Anders, Y. Bergmann, P. Goslawski, H. Hartmut, A. Jankowiak, J. Knobloch, A. Neumann, K. Ott, M. Ries, A. Schälicke, A.V. Vélez
    HZB, Berlin, Germany
 
  BESSY VSR is set out to provide a variable pulse pattern to the BESSY II users. This project is now fully funded and heading into its implementation phase. The pulse pattern, consisting of long and short pulses, require inserting cavities providing a 3rd and a 3.5th harmonic of the fundamental harmonic of the ring. Therefore 1.5 and 1.75 GHz cavities are developed with appropriate higher order mode damping spectrum. Similarly the BESSY II ring and injector chain has to be upgraded to provide appropriate diagnostics and increase the injection efficiency. In this paper we give the current status of the project and give an overview of scientific challenges currently being tackled.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF038  
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THPMF043 Development and Present Status of Photon Factory Light Sources injection, septum, operation, storage-ring 4155
 
  • T. Honda, Y. Kobayashi, S. Nagahashi, R. Takai
    KEK, Ibaraki, Japan
 
  Photon Factory of KEK manages two light sources, Photon Factory storage ring (PF-ring) and Photon Factory Advanced Ring (PF-AR) with an energy of 2.5 GeV and 6.5 GeV, respectively. Although it is unfortunate that the operation time of the accelerators is decreasing recent years due to a budget shortage and some unavoidable reconstructions, we are continuing the operation with a low failure rate and constructing a new beamline based on a novel undulator. Preparing for the start of the physics run of Super KEKB Factory, a new full energy beam transport line from the injector LINAC to PF-AR was constructed. With an installation of pulsed quadrupole magnets for the LINAC, continuous top-up injection has been established simultaneously for the four storage rings of PF and Super KEKB, and the operation of them has become compatible. As a result of increasing the injection energy of PF-AR form 3 GeV to 6.5 GeV, the beam instability during the injection disappeared, and the stability and efficiency of the injection improved significantly.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF043  
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THPMF046 Precision Charge Measurement of 40~MeV Electron-Beam to Calibrate Air Fluorescence Telescope for Cosmic Ray Observation electron, ECR, injection, ISOL 4163
 
  • T. Shibata
    KEK, Ibaraki, Japan
  • O.C. Shin
    OCU, Osaka, Japan
 
  The Telescope Array (TA) is ultra-high energy cosmic ray observation (UHECR). TA is using the fluorescence detectors (FD) for observation the air fluorescence(AFY) which are emitted in the cascade generated by an UHECR in atmosphere. One of the important observables is primary energy of UHECR, however it has 21% systematic uncertainty. For reduction of the uncertainty, we have been operated an 40-MeV electron linear accelerator from 2010 which we have constructed for absolute energy calibration. The accelerator is located at 100 m from FD station, and can shot electron beam which the direction is vertical into the air, the energy is 40-MeV, the pulse width is 1 micro-second, and the beam charge is 160 pC. The AFY efficiency and FD calibration parameters can be calibrated, which means energy scale of UHECR, by observation of the AFY which are generated by the electron beam in the air. The most important beam parameter is beam charge. The requirement of the accuracy of charge measurement is a few %, then we have developed the double faraday cups and one current transfer system. We calibrated the current transfer by the double faraday cups, and we could achieve about 1% accuracy.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF046  
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THPMF061 Updates on Hardware Developments for SPring-8-II electron, multipole, permanent-magnet, storage-ring 4209
 
  • T. Watanabe, S. Takano
    Japan Synchrotron Radiation Research Institute (JASRI), RIKEN SPring-8 Center, Hyogo, Japan
  • H. Tanaka
    RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
 
  We will report the updates on hardware developments for SPring-8-II including a status on a test half-cell construction. A major upgrade of SPring-8, SPring-8-II, targeting substantial improvements in the light source performance is based on a five-bend achromat lattice at an electron energy of 6 GeV*, and hardware accommodating with the new lattice have been extensively developed**. Some of key features are permanent dipole magnets, SUS vacuum chambers, highly accurate and reliable electron and photon beam position monitors, and an extremely small emittance beam injection from the SACLA linac to the storage ring. In the process of the optimization, we cannot rely merely on independent developments; the high packing factor lattice naturally imposes an integration of the individual efforts into a whole design. Thus, a test-half cell has been constructed as one of important milestones, where we need to carefully look through specification balances between different components, physical and magnetic interferences, etc. The presentation will give overall status on the developments as well as the test half-cell construction.
* H. Tanaka et al., Proc. of IPAC2016, Busan, Korea (2016), p.2867. K. Soutome and H. Tanaka, PRAB 20, 064001 (2017).
** e,g, T. Watanabe et al., PRAB 20, 072401 (2017).
 
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THPMF080 Physical and Chemical Roughness of Alkali-Animonide Cathodes cathode, electron, emittance, laser 4259
 
  • S.S. Karkare, S. Emamian, G. Gevorkyan, H.A. Padmore, A.K. Schmid
    LBNL, Berkeley, California, USA
  • I.V. Bazarov
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • A. Galdi
    Cornell University, Ithaca, New York, USA
 
  Over the last decade, alkali-antimonides have been investigated as high QE cathodes in green light and more recently as ultra-low intrinsic emittance cathodes in near-threshold red wavelengths at cryogenic temperatures*. Nano-meter scale surface non-uniformities (physical roughness and chemical roughness or work function variations) are thought to limit the smallest possible emittance from these materials at the photoemission threshold under cryogenic conditions**. Despite this, the surfaces of alkali-antimonides have not been well characterized in terms of the surface non-uniformities. Here, we present measurements of both the physical and chemical roughness of alkali-antimonide surfaces using several surface characterization techniques like atomic force microscopy, kelvin probe force microscopy, low energy electron microscopy and near-threshold photoemission electron microscopy and show how such non-uniformities limit the intrinsic emittance.
*L. Cultrera et al Phys. Rev. ST Accel. Beams 18, 113401 (2015)
**J. Feng et al, J. of Appl. Phys. 121, 044904 (2017)
 
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THPMK066 Cryogenic Permanent Magnet Undulator of SSRF permanent-magnet, undulator, SRF, cryogenics 4449
 
  • Y.Z. He, M.F. Qian, H.F. Wang, W. Zhang, Q.G. Zhou
    SINAP, Shanghai, People's Republic of China
 
  Funding: Work supported by the State Key Lab of Advanced Metals and Materials (2016-Z03) and the Youth Innovation Promotion Association of CAS (Grant No: 2017305)
The two Cryogenic Permanent Magnet Undulators (CPMU18 with PrFeB magnets P46H and CPMU20 with NdFeB magnets N48H) were designed and developed in SSRF in the past few years (2014-2017).This paper introduces magnetic performance of the permanent magnets, design parameters of the two CPMUs, cryogenic cooling and magnetic field of the two CPMUs and so on. When gap of the two CPMUs is about 6.0 mm, the measurement results showed that the effective magnetic field peak of CPMU18 at 300 K and 77 K was 0.82 T, 0.92T, respectively, and the magnetic field phase error is about 3 degrees and 5 degrees respectively. The effective magnetic field peak of CPMU20 at 300 K and 140 K was 0.94T and 1.03T, respectively, and the magnetic field phase error was 3 degrees and 3.5 degrees respectively.
 
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THPMK100 Setup for Cooled GaAs Cathodes With Increased Charge Lifetime cathode, electron, cryogenics, simulation 4542
 
  • T. Eggert, J. Enders, M. Espig, Y. Fritzsche, N. Kurichiyanil, M. Wagner
    TU Darmstadt, Darmstadt, Germany
 
  Funding: DFG (GRK 2128) BMBF (05H15RDRB1)
GaAs photocathode lifetime is limited, and to ensure re- liable operation for high power-applications it is necessary to maximize its charge lifetime. By using a cryogenic sub- volume it is expected to improve the local vacuum condi- tions due to cryogenic adsorption of reactive residual gas molecules. Yielding an enhanced lifetime of the negative- electron-affinity surface of the cathode. Furthermore the cooling of the cathode itself ishould allow higher laser power deposition in the material. Introducing an electrostatic bend is expected to reduces the ion-backbombardment on the cath- ode surface. A dedicated set-up is being developed at the Photo-CATCH test facility in Darmstadt, Germany to measure the charac- teristics of such a cryogenic source. This contribution updates the report given at PSTP 2017.
 
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THPMK125 Development of Non-Evaporable Getter (NEG) Coatings on Small Diameter Vacuum Chambers for Diffraction-Limited Storage Ring site, target, electron, storage-ring 4611
 
  • S. Wang, Y.Z. Hong, R. Huang, X.T. Pei, Y. Wang, W. Wei, B. Zhang, S.C. Zhang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  Design of the fourth generation Diffraction-Limited Storage Ring reduces aperture of vacuum chambers to a few centimeters. To satisfy the small aperture, the intense photon bombardment and the requirement of low pressure, most of the beam pipes need to be deposited with Ti-Zr-V nonevaporable getter (NEG) thin films. NEG can provide distributed pumping and low gas desorption and allow to achieve low pressure in narrow and conductance limited chambers. In this paper, Ti-Zr-V thin film was deposited by DC magnetron sputtering using Ti-Zr-V alloy target. The morphology and thickness of Ti-Zr-V are characterized by Scanning Electron Microscopy (SEM). The average grain size is evaluated using X-ray diffraction (XRD). The composition and the corresponding chemical bonding of the thin film are analyzed by X-ray Photoelectron Spectroscopy (XPS). Finally, the adhesion between the film and substrate and the vacuum performance are evaluated.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK125  
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THPML015 Dielectric Multipactor Discharges at 110 GHz multipactoring, cavity, experiment, GUI 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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THPML022 Application of Surface Plasmon Polaritons on Charged particle Beam Diagnostics radiation, electron, interface, diagnostics 4699
 
  • Z.G. Jiang, D. Gu, 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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THPML047 Design and Measurement of the X-Band Pulse Compressor for TTX cavity, GUI, coupling, ISOL 4745
 
  • Y.L. Jiang, H.B. Chen, C. Cheng, W. Gai, J. Shi, P. Wang, Z.H. Wang, 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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THPML053 Computational Screening for Low Emittance Photocathodes electron, cathode, database, emittance 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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THPML059 Re-Commissioning the Front End Test Stand Negative Hydrogen Ion Source, Beam Transport and Interlocks ion-source, rfq, MMI, high-voltage 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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THPML112 Preliminary Design and Calculation of Button BPM for the HALS Storage Ring storage-ring, HOM, electronics, impedance 4929
 
  • F.F. Wu, F.L. Gao, L.T. Huang, X.Y. Liu, P. Lu, B.G. Sun, J.H. Wei, Y.L. Yang, 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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THPML128 Production and Secondary Electron Yield Test of Amorphous Carbon Thin Film electron, synchrotron, synchrotron-radiation, site 4980
 
  • Y.X. Zhang, X.Q. Ge, S.W. Wang, 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 electron, controls, storage-ring, target 4983
 
  • X.Q. Ge, T.L. He, 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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THPML131 A NEW PRODUCTION PROCESS FOR UCx TARGETS FOR RADIOACTIVE ISOTOPE BEAMS AT TRIUMF target, TRIUMF, ISOL, ISAC 4990
 
  • 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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THPML135 Design of the Combined Function Dipole-Quadrupoles (DQS) with High Gradients quadrupole, dipole, lattice, storage-ring 5001
 
  • Z.L. Ren, C. Chen, T.L. He, 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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