Author: Huang, S.
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WEPOY019 Beam Optimization Study for an X-ray FEL Oscillator at the LCLS-II 3020
 
  • W. Qin, S. Huang, K.X. Liu
    PKU, Beijing, People's Republic of China
  • K.L.F. Bane, Y. Ding, Z. Huang, T.J. Maxwell
    SLAC, Menlo Park, California, USA
  • K.-J. Kim, R.R. Lindberg
    ANL, Argonne, Ilinois, USA
  
  The 4 GeV LCLS-II superconducting linac with high repetition beam rate enables the possibility to drive an X-Ray FEL oscillator at harmonic frequencies *. Compared to the regular LCLS-II machine setup, the oscillator mode requires a much longer bunch length with a relatively lower current. Also a flat longitudinal phase space distribution is critical to maintain the FEL gain since the X-ray cavity has extremely narrow bandwidth. In this paper, we study the longitudinal phase space optimization including shaping the initial beam from the injector and optimizing the bunch compressor and dechirper parameters. We obtain a bunch with a flat energy chirp over 400 fs in the core part with current above 100 A. The optimization was based on LiTrack and Elegant simulations using LCLS-II beam parameters.
* T. J. Maxwell et al., Feasibility study for an X-ray FEL oscillator at the LCLS-II, IPAC15, TUPMA028. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOY019  
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THPOW058 Drive Laser System for the DC-SRF Photoinjector at Peking University 4076
 
  • F.M. Liu, L.W. Feng, S. Huang, L. Lin, K.X. Liu, S.Y. Si, Zh.W. Wang, G. Zhao
    PKU, Beijing, People's Republic of China
  
  The DC-SRF photoinjector, developed at Peking University, uses Cs2Te as the photocathode and accordingly 266 nm laser is used as the drive laser. A drive laser sys-tem，which includes a 1064 nm laser oscillator, a four-stage amplifier, and second and fourth harmonic genera-tors, has been designed and applied successfully. To avoid the high average current electron beam from hitting the vacuum tube and causing safety problems, a laser pulse selector with an EO modulator has been designed and included into the laser drive system to reduce the repetition rate of electron pulses during the DC-SRF photoinjector commissioning. It can adjust the repetition rate of laser pulses from 81.25 kHz to 81.25 MHz. In this paper, we introduce the drive laser system and describe the laser pulse selector in detail.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW058  
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