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Ding, Y. T.

  
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MOBAU04 Optical Klystron Enhancement to SASE X-Ray FELs 29
 
  • Y. T. Ding, P. Emma, Z. Huang
    SLAC, Menlo Park, California
  • V. Kumar
    RRCAT, Indore (M. P.)
  
  The optical klystron enhancement to self-amplified spontaneous emission (SASE) free electron lasers (FELs) is studied in theory and in simulations. In contrast to a seeded FEL, the optical klystron gain in a SASE FEL is not sensitive to any phase mismatch between the radiation and the microbunched electron beam. The FEL performance with the addition of four optical klystrons located at the undulator long breaks in the Linac Coherent Light Source (LCLS) shows significant improvement if the uncorrelated energy spread at the undulator entrance can be controlled to a very small level. In addition, FEL saturation at shorter x-ray wavelengths (around 1.0 angstrom) within the LCLS undulator length becomes possible. We also discuss the application of the optical klystron in a compact x-ray FEL design that employs relatively low electron beam energy together with a shorter-period undulator.  
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THPPH062 Calculation of the Beam Field in the LCLS Bunch Length Monitor 728
 
  • G. V. Stupakov, Y. T. Ding, Z. Huang
    SLAC, Menlo Park, California
  
  Maintaining a stable bunch length and peak current is a critical step for the reliable operation of a SASE based x-ray source. In the LCLS, a bunch length monitor (BLM) right after the bunch compressors is proposed based on the coherent radiation generated by the short electron bunch*. Due to its diagnostic setup, the standard far field synchrotron radiation formula and well-developed numerical codes do not apply for the analysis of the BLM performance. In this paper, we develope a calculation procedure to take into account the near field effect, the effect of a short bending magnet, and the diffraction effect of the radiation transport optics. We find the frequency response of the BLM after the first LCLS bunch compressor and discuss its expected performance.

* J. Wu, P. Emma, Z. Huang, Proceedings of 2005 Particle Accelerator Conference 428.