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Kumar, V.

  
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WG312 Optical Klystron Enhancement to SASE X-ray FELs  
 
  • Z. Huang, Y. T. Ding, P. Emma
    SLAC, Menlo Park, California
  • V. Kumar
    ANL, Argonne, Illinois
  
  We study the optical klystron enhancement to SASE FELs in theory and 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.  
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WG341 Flat Electron Beams for a Smith-Purcell Backward Wave Oscillator for Intense Terahertz Radiation  
 
  • K.-J. Kim
    ANL, Argonne, Illinois
  • V. Kumar
    RRCAT, Indore (M. P.)
  
  A Smith-Purcell device can operate as a backward wave oscillator (BWO) producing a few watts of narrow bandwidth, CW Terahertz radiation. We discuss the requirements on electron beam properties for achieving the operation of such a device based on the results of a 2-D theory of Smith-Purcell BWO [1]. It is found that a specially designed non-relativistic electron beam is necessary with the current exceeding a certain threshold value and a flat transverse profile. Two methods for producing electron beams of required characteristics are discussed, one based on a line source and one employing the flat beam technique.

[1] V. Kumar and K.-J. Kim, Physical Review E 73, 026501 (2006).

 
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