Author: Zhao, Z.T.
Paper Title Page
TUPRB054 The Beam-Based Alignment Simulation and Preliminary Experiment at SXFEL 1804
 
  • L. Zeng, H.X. Deng, C. Feng, D. Gu, B. Liu, Z.T. Zhao
    SINAP, Shanghai, People’s Republic of China
  • G.L. Wang
    DICP, Dalian, People’s Republic of China
  
  The Shanghai soft X-ray Free-electron Laser facility (SXFEL) is now serving as an experimental platform for fundamental free-electron laser (FEL) principle tests. The machine puts very tight tolerance on the straightness of the electron beam orbit. It is hard to achieve the required trajectory due to the off-axis field of the misaligned quadrupoles and undulator segments especially for the SXFEL driven by low energy linac (840MeV). This tight requirement on electron beam straightness can only be met through the beam-based alignment (BBA) technology which achieved great success at LCLS, PAL-XFEL, European-XFEL and SCALA with high electron beam energies. But there has been no report about satisfactory BBA experiment results on soft X-ray FEL facility driven by relatively low energy linacs (on the order of 2 GeV or less) up to now. Here, we report the simulation results and preparatory experiment progress of the BBA at SXFEL with the method of dispersion-free steering (DFS). The experiment results show some improvements of the electron beam orbit and the phenomenon of the dispersion-free. The entire BBA experiment and a feedback system of electron beam trajectory may also be included.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB054  
About • paper received ※ 18 April 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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TUPGW110 Improvement of Touschek Lifetime by Higher Harmonic RF Cavity in the SPS Storage Ring 1669
 
  • T. Phimsen, N. Juntong, P. Sudmuang
    SLRI, Nakhon Ratchasima, Thailand
  • B.C. Jiang
    Shanghai Advanced Research Institute, Pudong, Shanghai, People’s Republic of China
  • Z.T. Zhao
    SSRF, Shanghai, People’s Republic of China
  
  Siam Photon Source (SPS), located at Nakhon Ratchasima, Thailand, is a synchrotron light source with the beam energy of 1.2 GeV. User operation is performed in beam decay mode with the maximum current of 150 mA. Beam lifetime is about 12 hours at the beam current of 100 mA. Beam injection is carried out twice a day, and even with full energy, it takes roughly 30 minutes. Beam lifetime in the SPS storage ring is limited by Touschek scattering and strongly depends on operation conditions. Higher harmonic RF cavity is a proven method to increase the beam lifetime and suppressing coupled bunch instabilities through Landau damping effect. If the beam lifetime is increased for examples, to be double, only one injection per day would be needed. In this study, an improvement of Touschek lifetime by passive harmonic RF cavity is investigated.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW110  
About • paper received ※ 14 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPRB055 First Results of the IVU16 Prototype Undulator Measurements 1808
 
  • C. Yu, Y.Z. He, X. Hu, Z. Jiang, M.F. Qian, Y.M. Wen, S. Xiang, L. Yin, J.D. Zhang, W. Zhang, Q.G. Zhou
    SINAP, Shanghai, People’s Republic of China
  • H.X. Deng, B. Liu, D. Wang
    SARI-CAS, Pudong, Shanghai, People’s Republic of China
  • H.F. Wang, Z.T. Zhao
    SSRF, Shanghai, People’s Republic of China
  
  The Shanghai Synchrotron Radiation Facility (SSRF) has developed a 16 mm period length, 4 mm gap, in-vacuum undulator (IVU) that is planned to be installed and tested in the 1.5 GeV SXFEL-SBP beam line. This paper will describe the main parameters of the undulator and the key design choices that have been made. The first undulator prototype was assembled and magnetically tested. First measurements with vacuum chamber will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB055  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPTS054 1st+2nd Harmonic Photocathode Bimodal Gun R&D 2054
SUSPFO086   use link to see paper's listing under its alternate paper code  
 
  • L. Wang
    SINAP, Shanghai, People’s Republic of China
  • W. Fang, Z.T. Zhao
    SSRF, Shanghai, People’s Republic of China
  • J.L. Hirshfield
    Yale University, Physics Department, New Haven, CT, USA
  • J.L. Hirshfield, S.V. Shchelkunov
    Omega-P, Inc., New Haven, Connecticut, USA
  • Y. Jiang, S.V. Shchelkunov
    Yale University, Beam Physics Laboratory, New Haven, Connecticut, USA
  • L. Wang
    University of Chinese Academy of Sciences, Beijing, People’s Republic of China
  
  Funding: U.S. Dept. of Energy
A novel Bimodal Electron Gun is designed to apply microwaves at two harmonically-related frequency in a 0.6 cell RF gun to increase the RF breakdown threshold and enhance the beam quality. This stratagem is intended to allow the RF gun structure to support a high accelera-tion gradient as well as to manipulate the emittance evolution in the half cell. By selecting a proper ampli-tude ratio and phase relationship between the first and second harmonic RF field components in the gun cavity, the superposition of the harmonic field components can provide a flat-top like RF profile to omitting the RF emittance component in the gun, while increase the RF breakdown threshold. The recent status of the Bimodal Electron Gun R&D is presented, including the designs of the novel two frequency RF structure and the simulation of the beam dynamic. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS054  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPTS085 Design Study of 3.6-cell C-band Photocathode Electron Gun 2121
 
  • W. Fang, Z.T. Zhao
    SSRF, Shanghai, People’s Republic of China
  • L. Wang
    University of Chinese Academy of Sciences, Beijing, People’s Republic of China
  • L. Wang
    SINAP, Shanghai, People’s Republic of China
  
  A C-band photocathode injector composed of a 3.6-cell C-band photocathode RF gun and two 1.8-meter C-band accelerating structures is proposed. The injector is a low emittance electron source for Free Electron Lasers (FEL) and other compact light sources. The RF structure of the cavities is designed with 2D SUPERFISH simulation. The Beam dynamic study in ASTRA helps rectify the 2D RF simulation. To feed the cavities, a design of extra coaxial coupler with RF gun structure is presented. With compact focusing solenoids, for 0.25nC bunch charge, the final energy can reach 6.9 MeV energy and the 95% emittance can be as low as 0.23 mm mrad (95%). All the details of RF design and beam dynamics studies are presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS085  
About • paper received ※ 15 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
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WEPRB034 Study on the Design of the X-band Waveguide-damped Structure 2886
 
  • X.X. Huang, W. Fang, Z.T. Zhao
    SSRF, Shanghai, People’s Republic of China
  • A. Grudiev
    CERN, Meyrin, Switzerland
  
  The design of waveguide-damped structure is optimized to reduce the magnitudes of surface electromagnetic fields and strongly suppress long-range transverse wakefields of the 380 GeV Compact Linear Collider facility currently under study. The optimization is mainly discussed with the elliptical shape of the iris, the wall shape of the damping waveguides, the position of the high-order-mode damping loads and the widths of the waveguide openings of the entire sequence of damping waveguides.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB034  
About • paper received ※ 13 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPRB042 High Power Test of the First C-band Spherical Pulse Compressor Prototype 2896
 
  • Z.B. Li
    SINAP, Shanghai, People’s Republic of China
  • W. Fang, Q. Gu, X.X. Huang, J.H. Tan, Z.T. Zhao
    SSRF, Shanghai, People’s Republic of China
  
  Funding: National Natural Science Foundation of China (No. 11675249)
Recently, a new C-band (5712 MHz) compact spherical radio frequency (RF) pulse compressor was designed and tested for Shanghai Soft X-ray Free Electron Laser Facili-ty (SXFEL). This pulse compressor utilizes one high Q0 spherical RF resonant cavity that works with two TE1, 1,3 modes and a dual-mode polarized coupler. The peak power multiply factor is 6.1 and average power gain 3.8 in theory. During the high power test, a peak power mul-tiply factor of 5.74 and average power gain of 3.77 was achieved. This paper presents the RF measurement of the C-band spherical pulse compressor and the high power test results. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB042  
About • paper received ※ 19 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPRB048 Design, Fabricate, and Tuning of X-Band Deflecting Structure for CERN 2915
 
  • J.H. Tan, W. Fang, Q. Gu, X.X. Huang, Z.T. Zhao
    SSRF, Shanghai, People’s Republic of China
  
  A 20-cell x-band deflecting structure for CERN has been finished, and now is under high power conditioning at XBOX of CERN.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB048  
About • paper received ※ 14 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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