Keyword: laser
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MO2A03 Technology Developments for ELI-NP Gamma Beam System gun, linac, electron, vacuum 13
 
  • L. Piersanti, D. Alesini, A. Battisti, M. Bellaveglia, S. Bini, F. Cardelli, R.D. Di Raddo, A. Falone, A. Gallo, V.L. Lollo, L. Pellegrino, S. Pioli, S. Tomassini, A. Variola
    INFN/LNF, Frascati (Roma), Italy
  • N. Beaugerard
    SEIV, Mérignac, France
  • K. Cassou, D. Douillet, K. Dupraz, T. Le Barillec, A. Martens, C.F. Ndiaye, Y. Peinaud, Z.F. Zomer
    LAL, Orsay, France
  • L. Ficcadenti, A. Mostacci, L. Palumbo, V. Pettinacci
    INFN-Roma, Roma, Italy
  • M. Migliorati
    INFN-Roma1, Rome, Italy
  • D.T. Palmer, L. Serafini
    Istituto Nazionale di Fisica Nucleare, Milano, Italy
  • H. Rocipon
    ALSYOM, Argebteuil, France
 
  ELI-NP gamma beam system (GBS) is a linac based gamma-source in construction in Magurele (RO) by the European consortium EuroGammaS led by INFN. Photons with tunable energy, from 0.2 to 19.5 MeV, and with intensity and brilliance beyond the state of the art, will be produced by Compton back-scattering between a high quality electron beam (up to 740 MeV) and an intense laser pulse at 100 Hz repetition rate. Production of very intense photon flux with narrow bandwidth requires multi-bunch operation and laser recirculation at the interaction point. In this paper, the main technological developments carried out by the EuroGammaS consortium for the generation of the ELI-NP gamma beam will be described with a special emphasis on the electron linac technology, such as: RF-gun and C-band accelerating structures design fabrication and tests; low level RF (LLRF) and synchronization systems specifications and development. Finally, the laser recirculation apparatus design is briefly described and first results reported.  
slides icon Slides MO2A03 [9.121 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MO2A03  
About • paper received ※ 11 September 2018      issue date ※ 18 January 2019  
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MO2A04 Compact SRF Linac for High Brilliance Inverse Compton Scattering Light Source electron, brilliance, emittance, gun 19
 
  • K.E. Deitrick, J.R. Delayen, G.A. Krafft, B. Terzić
    ODU, Norfolk, Virginia, USA
  • J.R. Delayen, G.A. Krafft
    JLab, Newport News, Virginia, USA
 
  New designs for compact SRF linacs can produce micron-size electron beams. These can can be used for inverse Compton scattering light sources of exceptional flux and brilliance.  
slides icon Slides MO2A04 [1.717 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MO2A04  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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MOPO007 The Developing of the Beam Injection Section with Laser Source and S-Band Electron RF Gun for SuperKEKB Project gun, electron, MMI, emittance 50
 
  • X. Zhou, Y. Ogawa, M. Yoshida, R. Zhang
    KEK, Ibaraki, Japan
 
  For the beam injection at Linac Accelerator of the SuperKEKB project, the s-band RF gun needs to provide low-emittance high-charge electron bunches. An ultrashort high energy solid laser driving a cathode in a quasi-travelling side-coupled RF gun were developed. A Yb fiber and Nd:YAG hybrid laser amplify system is start with 114.24 MHz oscillator that synchronized from accelerator. Two beam lines with the 25Hz, ~20ps, and sub-mJ Ultraviolet pulses were generated to RF gun. Ir5Ce has long lifetime and quantum efficiency QE that was employed to cathode. The RF gun has two side coupled cavities on same axis can realize quasi-traveling wave, which is suitable for the high charge and low emittance beam generation. Now, great progress has been made to make the RF gun function well. For the Phase II commissioning, required charge and emittance were achieved.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO007  
About • paper received ※ 05 September 2018      issue date ※ 18 January 2019  
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MOPO008 The RF Gun Adopting the Dielectric Assist Accelerating Structure cavity, electron, cathode, emittance 54
 
  • S. Mori, D. Satoh, M. Yoshida
    KEK, Ibaraki, Japan
 
  We apply the dielectric assist accelerating (DAA) structure to the RF gun, which is a candidate for a high average current and high brightness electron source. The DAA structure consists of ultralow-loss dielectric cylinders and disks which are periodically arranged in a metallic enclosure. Due to the high quality factor and the high shunt impedance of the DAA cavity, the RF gun adopting the DAA cavity can be a high-duty electron beam source at room temperature. We provide design work for RF gun adopting the DAA structure.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO008  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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MOPO009 ELI-NP Gamma Beam System - Current Project Status linac, gun, electron, experiment 59
 
  • P.S. Tracz
    IFIN-HH, Bucharest - Magurele, Romania
 
  The Gamma Beam System at the ELI-NP under construction in Magurele/Bucharest Romania, aims at producing high brilliance gamma-rays based on the laser Compton back-scattering, up to 3.5 and 19.5 MeV out of two interaction chambers. The design of warm RF electron linac is optimized to meet the unique source specification i.e. high brilliance, small relative bandwidth, tunable energy, and high spectral density. Together with technological development in field of high energy/high quality lasers it will open new opportunities for nuclear physics research in fields like nuclear photonics, nuclear astrophysics, photo-fission, and production of exotic nuclei, applications in industry, medicine, and space science. S-band laser driven RF photo-gun and two accelerating structures constitute the injector. The beam is then accelerated by C-band linac up to 350MeV (low energy linac), and up to 720MeV (high energy linac). The GBS was designed and is being constructed by the EuroGammaS - a consortium of European academic and research institutions and industrial partners. This paper gives an overview of the facility, describes the main linac systems and summarizes the project status.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO009  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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MOPO010 JINR Photocathode Research: Status and Plans cathode, electron, gun, scattering 62
 
  • M.A. Nozdrin, N. Balalykin, J. Huran, V.F. Minashkin, G. Shirkov
    JINR, Dubna, Moscow Region, Russia
  • E. Gacheva, A. Poteomkin, V. Zelenogorsky
    IAP/RAS, Nizhny Novgorod, Russia
  • J. Huran
    Slovak Academy of Sciences, Institute of Electrical Engineering, Bratislava, Slovak Republic
 
  Photocathode research in the frame of the "transmission" photocathode conception (backside illuminated cathode based on a quartz/sapphire plate or a metal mesh which is a substrate for thin film made of a photomaterial) is being conducted in the Veksler and Baldin Laboratory of High Energy physics (LHEP) of the Joint Institute for Nuclear Research (JINR). Status of the 30-kev DC Photogun test bench and recent results of the extremely thin carbon film based cathodes research are described. Progress in the full-scale photoinjector prototype (max electron energy of 400 keV) is given. Startup of the photoinjector was performed, 70 keV electrons were extracted (650 pC).  
poster icon Poster MOPO010 [1.564 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO010  
About • paper received ※ 11 September 2018      issue date ※ 18 January 2019  
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MOPO027 Photocathode Laser Pulse Shaping for Improved Emittance cathode, electron, gun, emittance 84
 
  • M. Kotur, J. Andersson, J. Björklund Svensson, M. Brandin, F. Curbis, L. Isaksson, F. Lindau, R. Lindvall, E. Mansten, R. Svärd, S. Thorin, S. Werin
    MAX IV Laboratory, Lund University, Lund, Sweden
 
  We present a setup for producing and characterizing picosecond ultraviolet laser pulses for use in the MAX IV photocathode electron gun preinjector. Frequency-tripled laser pulses from a commercial laser system are shaped directly in the ultraviolet domain using a Fourier-domain pulse shaper. The pulses were characterized using a transitent grating FROG. We discuss a proposed upgrade of the pulse shaper, as well as its limitations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO027  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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MOPO035 Status of CLARA Front End Commissioning linac, GUI, cathode, MMI 98
 
  • D. Angal-Kalinin, A.D. Brynes, S.R. Buckley, P.A. Corlett, L.S. Cowie, K.D. Dumbell, D.J. Dunning, P.C. Hornickel, F. Jackson, J.K. Jones, J.W. McKenzie, B.L. Militsyn, A.J. Moss, T.C.Q. Noakes, M.D. Roper, D.J. Scott, B.J.A. Shepherd, E.W. Snedden, N. Thompson, C. Tollervey, D.A. Walsh, T.M. Weston, A.E. Wheelhouse
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • R.J. Cash, R.F. Clarke, G. Cox, C. Hodgkinson, R.J. Smith, J.T.G. Wilson
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
  • K.D. Dumbell, B.J.A. Shepherd
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
 
  CLARA (Compact Linear Accelerator for Research and Applications) is a Free Electron Laser (FEL) test facility under development at Daresbury Laboratory. The principal aim of CLARA is to test advanced FEL schemes which can later be implemented on existing and future short wavelength FELs. We report on the commissioning of the CLARA front end, consisting of a photoinjector and the first linac section, and merger into the existing VELA (Versatile Electron Linear Accelerator) beamline.  
slides icon Slides MOPO035 [1.870 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO035  
About • paper received ※ 11 September 2018      issue date ※ 18 January 2019  
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MOPO037 SRF Gun Development at DESY gun, cathode, cavity, SRF 105
 
  • E. Vogel, S. Barbanotti, I. Hartl, K. Jensch, D. Klinke, D. Kostin, W.-D. Möller, M. Schmökel, J.K. Sekutowicz, S. Sievers, N. Steinhau-Kühl, A.A. Sulimov, J.H. Thie, H. Weise, L. Winkelmann, B. van der Horst
    DESY, Hamburg, Germany
  • J.A. Lorkiewicz, R. Nietubyć
    NCBJ, Świerk/Otwock, Poland
  • J. Smedley
    BNL, Upton, Long Island, New York, USA
  • J. Teichert
    HZDR, Dresden, Germany
  • M. Wiencek
    IFJ-PAN, Kraków, Poland
 
  A future upgrade of the European XFEL (E-XFEL) foresees an additional cw operation mode increasing the flexibility in the photon beam time structure. This mode requires among others a cw operating photo injector. We believe that using an SRF gun is the preferred approach as the beam parameters of normal conducting pulsed guns can be potentially met by SRF guns operating cw. Since more than a decade DESY in collaboration with TJNAF, NCBJ, BNL, HZB and HZDR performs R&D to develop an all superconducting RF gun with a lead cathode. In the frame of E-XFEL cw upgrade feasibility studies, the SRF-gun R&D program gained more attention and support. Within the next few years we would like to demonstrate the performance of the all superconducting injector required for the E-XFEL upgrade. The selected approach offers advantages w.r.t. the cleanliness of the superconducting surface, but requires a complete disassembly of a cryostat and stripping the gun cavity in a clean room to exchange the cathode. Thus it is practical only when the life time of the cathode is at least several months. In this paper we present the actual status of the R&D program, next steps and the longer term plans.  
slides icon Slides MOPO037 [1.966 MB]  
poster icon Poster MOPO037 [3.774 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO037  
About • paper received ※ 11 September 2018      issue date ※ 18 January 2019  
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MOPO039 Status Update of the Fast Energy Corrector Cavity at FLASH cavity, electron, coupling, free-electron-laser 112
 
  • S. Pfeiffer, J. Branlard, L. Butkowski, M. Hierholzer, M. Hoffmann, K. Honkavaara, H. Schlarb, Ch. Schmidt, S. Schreiber, M. Vogt, J. Zemella
    DESY, Hamburg, Germany
  • M. Fakhari
    CFEL, Hamburg, Germany
 
  Funding: The work is part of EuCARD-2, partly funded by the European Commission, GA 312453.
Linear accelerator facilities driving a free-electron laser require femtosecond precision synchronization between external laser systems and the electron beam. Such high precision is required for pump-probe experiments and also for example for the electron bunch injection into a plasma bubble for laser plasma acceleration. An upgrade of the fast intra-train beam-based feedback system is planned at the Free-Electron Laser FLASH in Hamburg, Germany. This linear accelerator is based on superconducting (SRF) technology operating with pulse trains of maximum 1 MHz bunch repetition rate. Arrival time fluctuations of the electron beam are correctable by introducing small energy modulations prior to the magnetic bunch compressor. This contribution focuses on the design and the characterization of a normal-conducting RF (NRF) cavity with large bandwidth, mandatory to correct fast arrival time fluctuations. The cavity has recently been installed in the FLASH beamline. First measurements with the new cavity will be presented.
 
poster icon Poster MOPO039 [1.884 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO039  
About • paper received ※ 13 September 2018      issue date ※ 18 January 2019  
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MOPO040 Coherent Synchrotron Radiation Monitor for Microbunching Instability in XFEL radiation, electron, bunching, FEL 115
 
  • J.H. Ko, I.S. Ko
    POSTECH, Pohang, Kyungbuk, Republic of Korea
  • H.-S. Kang, C. Kim, G. Kim
    PAL, Pohang, Kyungbuk, Republic of Korea
 
  The microbunching instability is an important issue in an X-ray Free Electron Laser (XFEL). The intensity of the FEL can be reduced significantly by the microbunching instability so that the laser heater is widely used to reduce it. In the X-ray Free Electron Laser of the Pohang Accelerator Laboratory (PAL-XFEL), to directly monitor the microbunching instability, a visible CCD camera was included into the coherent radiation monitor (CRM) which uses a pyroelectric detector. It enabled us to measure the microbunching instability more clearly and optimize the FEL lasing in the PAL-XFEL.  
slides icon Slides MOPO040 [1.125 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO040  
About • paper received ※ 11 September 2018      issue date ※ 18 January 2019  
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MOPO042 Evolutionary Many-objective Optimization Algorithm for Large-bandwidth Free-Electron-Laser Generation electron, FEL, free-electron-laser, linac 121
 
  • J.W. Yan, H.X. Deng
    SINAP, Shanghai, People’s Republic of China
 
  Funding: National Natural Science Foundation of China , the National Key Research and Development Program of China, the Young Elite Scientist Sponsorship Program by CAST and Ten Thousand Talent Program.
X-ray free-electron lasers (XFELs) are leading-edge instruments in a wide range of research fields. Besides pursuing narrow bandwidth FEL pulses, the large-bandwidth XFEL pulses are very useful in various spectroscopy experiments, multi-wavelength anomalous diffraction, and X-ray crystallography. Overcompression operation scheme can be utilized to generate electron beams with large energy chirp which is benefit for bandwidth broadening. Recently, an evolutionary many-objective (having four or more objectives) algorithm, NSGA-III, was used to optimize the electron beam parameters in the overcompression including energy chirp, energy spread, current profile, peak current, and projected emittance. In this paper, combining with the Xie’s semianalytical estimate formula, the NSGA-III is utilized to find an optimal working point of linac by optimizing the XFEL pulse properties directly. Start-to-end numerical simulations based on the Shanghai soft X-ray Free-Electron Laser user facility parameters demonstrate that a full bandwidth of 4.75% can be generated.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO042  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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MOPO115 CEBAF Photo Gun RF System FPGA, operation, gun, MMI 236
 
  • T. E. Plawski, R. Bachimanchi, M. Diaz, H. Higgins, C. Hovater, C.I. Mounts, D.J. Seidman
    JLab, Newport News, Virgina, USA
 
  Funding: Authored by JSA, LLC under U.S. DOE Contract DE-AC05- 06OR23177 and DE-SC0005264.
During the CEBAF 12 GeV Upgrade at Jefferson Lab, a fourth experimental hall, ’D’, was added to the existing three halls. To produce four beams and deliver them to all halls concurrently requires new frequencies and a new timing pattern of the electron bunches. Since a photo-gun is used to produce electron bunches, the gun’s drive laser pulses need to be synchronized with the required bunch rate frequencies of 499 MHz or 249.5 MHz. To meet these new operational requirements, the new LLRF system has been proposed. Very specific requirements (dual frequency operation) on one side and the simple RF drive mode operation on the other imply the use of a commercial off-the-shelf digital platform rather than a system typical for RF cavity field control. We have chosen the Texas Instruments FPGA board along with a high-speed 8-Channel, 14-Bit board, and a 4-Channel, 16-Bit board. The DAC board includes the clock generator for clocking ADCs, DACs and the FPGA. The complete Gun Laser LLRF system has been designed, built, and recently commissioned in the CEBAF Injector. This paper will detail the design and report on commissioning activities.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO115  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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MOPO121 Large-Scale Optical Synchronization System of the European XFEL FEL, timing, experiment, electron 253
 
  • J.M. Müller, M. Felber, T. Kozak, T. Lamb, H. Schlarb, S. Schulz, C. Sydlo, M. Titberidze, F. Zummack
    DESY, Hamburg, Germany
 
  At the European XFEL, a facility-wide optical synchronization system providing a femtosecond-stable timing reference at more than 40 end-stations had been developed and installed. The system is based on an ultra-stable, low-noise laser oscillator, whose signals are distributed via actively length-stabilized optical fibers to the different locations across the accelerator and experimental areas. There, it is used to locally re-synchronize radio frequency signals, to precisely measure the arrival time of the electron beam for fast beam-based feedbacks, and to phase-lock optical laser systems for electron bunch generation, beam diagnostics and user pump-probe experiments with femtosecond temporal resolution. In this paper, we present the system’s architecture and discuss design choices to realize an extensible, large-scale synchronization infrastructure for accelerators that meets reliability, maintainability as well as the performance requirements. Furthermore, the latest performance result of an all-optically synchronized laser oscillator is shown.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO121  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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TUPO011 Upgrade of Heavy Ion Injector I-3 at ITEP acceleration, heavy-ion, emittance, ion-source 346
 
  • N.N. Alexeev, P.N. Alekseev, V. Andreev, T. Kulevoy, A.D. Milyachenko, V.I. Nikolaev, Yu.A. Satov, A. Shumshurov, A. Zarubin
    ITEP, Moscow, Russia
 
  Heavy ion injector I-3 represents two-gap 2.5 MHz resonator with accelerating voltage 2x2 MV. It‘s used with laser ion source for acceleration of heavy ions in wide range of charge to mass ratio. As a result of modernization, injector structure will be supplemented by the second two-gap resonator, rf voltage will be increased to 3x4 MV and accelerated beam structure has to be improved by increasing accelerating frequency to 5 MHz. Design features of upgraded linac and peculiarity of beam dynamics for different types of ions are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO011  
About • paper received ※ 03 September 2018      issue date ※ 18 January 2019  
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TUPO048 Study Progress of Pulse Laser Annealing for Niobium Film on Copper ECR, niobium, experiment, cavity 438
 
  • Y. Yang, B.T. Li, X.Y. Lu, W.W. Tan, L. Xiao, D. Xie, D.Y. Yang
    PKU, Beijing, People’s Republic of China
 
  Funding: Work supported by Major Research Plan of National Natural Science Foundation of China (No. 91026001).
The recent studies of laser annealing on niobium films on copper are reported. Annealing is normally used to deal with the surface, reducing defects and even chang-ing the microstructure of the coating film. Short pulse laser can produce a sharp step temperature field on the film thickness scale (μm), which anneals the surface without substrate heated. The laser annealing experi-ments of niobium thin film sample have been carried out, and according to SEM and FIB results, Nb films melted and recrystallization occurred. Grains growing up can be observed while the power density of laser pulse in-creased.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO048  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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TUPO098 Proof-of-Principle Tests for Slit-scan-based Slice Emittance Measurements at PITZ emittance, electron, FEL, cathode 553
 
  • R. Niemczyk, P. Boonpornprasert, Y. Chen, J.D. Good, M. Groß, H. Huck, I.I. Isaev, D.K. Kalantaryan, C. Koschitzki, M. Krasilnikov, X. Li, O. Lishilin, G. Loisch, D. Melkumyan, A. Oppelt, H.J. Qian, Y. Renier, C. Saisa-ard, F. Stephan, Q.T. Zhao
    DESY Zeuthen, Zeuthen, Germany
  • W. Hillert
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
 
  Transverse slice emittance is one of the most important properties of high-brightness electron beams for freeelectron lasers (FELs). The photo injector test facility at DESY in Zeuthen (PITZ) develops high-brightness electron sources for modern FELs. With a 23 MeV, 1 nC beam at PITZ the experimental slice emittance characterization with the quadrupole scan technique is complicated by strong space charge effects. Combining the slit scan technique with a transverse deflecting cavity (TDS) allows for timeresolved emittance measurements of such a space-chargedominated beam. The first proof-of-principle results of slice emittance measurements at PITZ based on the ’TDS + slit scan’-technique are presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO098  
About • paper received ※ 04 September 2018      issue date ※ 18 January 2019  
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TH1A05 Jitter Study for the APS Linac Photo-injector Beam timing, linac, experiment, simulation 647
 
  • D. Hui, M. Borland, J.M. Byrd, Y. Sun
    ANL, Argonne, Illinois, USA
 
  Funding: *Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The APS Linac photo-injector can deliver high brightness electron beams to the Linac Extension Area (LEA) for beam experiments such as TESSA (Tapering Enhanced Stimulated Superradiant Amplification). Beam jitter in the device-under-test (DUT) area of the LEA can adversely affect the quality of data for such experiments. In this paper, a start-to-end simulation of jitter is studied. Sources of jitter include photo-cathode drive-laser arrival time, laser energy, and RF phases and voltages of the photo-cathode gun and accelerating cavities. It is found that at the DUT the relative mean energy jitter is the most significant concern, and that improvements in the Linac RF voltage stability can help to reduce it. RMS energy spread are more sensitive to the laser timing and charge jitter. The laser timing jitter itself can be compressed by the magnetic chicane by a factor of 5.6.
 
slides icon Slides TH1A05 [4.377 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TH1A05  
About • paper received ※ 10 September 2018      issue date ※ 18 January 2019  
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THPO116 Space-Charge Dominated Photoemission in High Gradient Photocathode RF Guns cathode, space-charge, emittance, gun 941
 
  • Y. Chen, P. Boonpornprasert, J.D. Good, M. Groß, H. Huck, I.I. Isaev, D.K. Kalantaryan, C. Koschitzki, M. Krasilnikov, O. Lishilin, G. Loisch, D. Melkumyan, R. Niemczyk, A. Oppelt, H.J. Qian, Y. Renier, F. Stephan
    DESY Zeuthen, Zeuthen, Germany
  • H. Chen, Y. C. Du, W.-H. Huang, C.-X. Tang, Q.L. Tian, L.X. Yan
    TUB, Beijing, People’s Republic of China
  • H. De Gersem, E. Gjonaj
    TEMF, TU Darmstadt, Darmstadt, Germany
  • M. Dohlus
    DESY, Hamburg, Germany
  • S. A. Schmid
    Institut Theorie Elektromagnetischer Felder, TU Darmstadt, Darmstadt, Germany
 
  The cathode emission physics plays a crucial role in the overall beam dynamics in the gun. Interplays between intricate emission mechanisms in the cathode vicinity strongly influence the cathode quantum efficiency (QE) and the intrinsic emittance. The presence of strong space-charge effects in high gradient RF guns further complicates the emission process. A proper modeling of photoemission and a careful treatment of the space-charge contribution is thus of great necessity to understanding the formation of the beam slice emittance. In this article, emission measurements are carried out using the L-band cesium-telluride photocathode RF gun at the Photo Injector Test Facility at DESY in Zeuthen (PITZ) and the S-band copper photocathode RF gun at Tsinghua University. Following the Dowell model a simple so-called space-charge iteration approach is developed and used to determine the QE through temporal and spatial-dependent electromagnetic fields. An impact of the space-charge cooling on the thermal emittance is presented. Measurement data are shown and discussed in comparisons to preliminary simulation results.  
slides icon Slides THPO116 [6.249 MB]  
poster icon Poster THPO116 [3.157 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO116  
About • paper received ※ 11 September 2018      issue date ※ 18 January 2019  
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THPO125 Runing Status of SRF Gun II at the ELBE Radiation Center gun, SRF, cathode, operation 952
 
  • R. Xiang, A. Arnold, P.N. Lu, P. Murcek, J.S. Schaber, J. Teichert, H. Vennekate, P.Z. Zwartek
    HZDR, Dresden, Germany
 
  Funding: The work is supported by the German Federal Ministry of Education and Research (BMBF) grant 05K12CR1 and the Deutsche Forschungsgemeinschaft (DFG) grant XI106/2-1.
As a new electron source with higher brilliance, the second version of the superconducting RF photoinjector (SRF Gun II) has been successfully commissioned at the ELBE Center for High-Power Radiation Sources since 2014. SRF Gun II features an improved 3.5-cell niobium cavity as well as a superconducting solenoid in the same cryomodule. For user operation the SRF Gun II with Mg photocathode successfully generated stable beam with bunch charges up to 200 pC in CW mode, and with sub-ps bunch length. In this presentation the gun’s status and beam parameters will be presented.
 
poster icon Poster THPO125 [1.520 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO125  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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FR1A06 Pulse-by-Pulse Beam Parameter Switching of High-Quality Beams for Multi-Beamline Operation at SACLA FEL, electron, controls, optics 988
 
  • H. Maesaka, T. Fukui, T. Hara, Y. Otake
    RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
  • T. Hasegawa, O. Morimoto, Y. Tajiri, S. Tanaka, M. Yoshioka
    SES, Hyogo-pref., Japan
  • N. Hosoda, S. Matsubara, T. Ohshima
    JASRI/SPring-8, Hyogo-ken, Japan
  • C. Kondo, M. Yamaga
    JASRI, Hyogo, Japan
 
  The main linac of the X-ray free electron laser (XFEL), SACLA, provides electron beams to two XFEL beamlines and a beam transport line to the SPring-8 storage ring. In order to utilize these beamlines at the same time, a kicker magnet was installed into the switch yard and electron beams with a 60 Hz repetition rate can be distributed to these beamlines pulse-by-pulse. Since a beam energy and an optimum bunch length are usually different for each beamline, the operation condition of each acceleration unit, such as the rf phase, the trigger permission, etc., has to be changed pulse-by-pulse. Even in that case, the electron beam quality, such as 1 mm mrad normalized emittance, 10 fs bunch length, 10 kA peak current, etc., must not be deteriorated. At first, we developed a parameter control software that was able to manage two XFEL beamlines with an equal repetition rate. Different energy beams with sufficient quality for lasing were successfully distributed to the two XFEL beamlines and the XFEL performances of both beamlines were optimized simultaneously. The development status of a new parameter switching system with an arbitrary sequence of the destinations will also be reported.  
slides icon Slides FR1A06 [6.179 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-FR1A06  
About • paper received ※ 16 September 2018      issue date ※ 18 January 2019  
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