Author: Decker, F.-J.
Paper Title Page
Generation of High Power, Short X-Ray FEL Pulses  
  • M.W. Guetg, F.-J. Decker, Y. Ding, Z. Huang, A.A. Lutman, T.J. Maxwell
    SLAC, Menlo Park, California, USA
  X-ray Free Electron Lasers combine high pulse power, short pulse length, narrow bandwidth and a high degree of transverse coherence. Increasing the photon pulse power, while shortening the pulse length, is of key importance on the way to single molecule imaging. This letter shows experimental results at the Linac Coherent Light Source improving its power to more than 300 GW, while reducing the photon pulse length to 10fs. This was achieved by removing residual transverse-longitudinal centroid beam offsets and correction of dispersion when operating over 6 kA peak current.  
Recent Developments and Plans for Two Bunch Operation with up to 1 μs Separation at LCLS  
  • F.-J. Decker, K.L.F. Bane, W.S. Colocho, A.A. Lutman, J.C. Sheppard
    SLAC, Menlo Park, California, USA
  Funding: Work supported by U.S. Department of Energy, Contract DE-AC02-76SF00515.
To get two electron bunches with a separation of up to 1 microsecond at the Linac Coherent Light Source (LCLS) is important for LCLS-II developments. Two lasing bunches up to 220 ns have been demonstrated. Many issues have to be solved to get that separation increased by a factor of 5. The typical design and setup for one single bunch has to be questioned for many devices: RF pulse widths have to be widened, BPMs diagnostic can see only one bunch or a vector average, feedbacks have to be doubled up, the main Linac RF needs to run probably un-SLEDed, and special considerations have to be done for the Gun and L1X RF.
Beam Shaping to Improve the Free-Electron Laser Performance at the Linac Coherent Light Source  
  • Y. Ding, K.L.F. Bane, W.S. Colocho, F.-J. Decker, P. Emma, J.C. Frisch, M.W. Guetg, Z. Huang, R.H. Iverson, J. Krzywinski, H. Loos, A.A. Lutman, T.J. Maxwell, H.-D. Nuhn, D.F. Ratner, J.L. Turner, J.J. Welch, F. Zhou
    SLAC, Menlo Park, California, USA
  A new operating mode has been developed for the Linac Coherent Light Source (LCLS) in which we shape the longitudinal phase space of the electron beam. This mode of operation is realized using a horizontal collimator located in the middle of the first bunch compressor to truncate the head and tail of the beam. With this method, the electron beam longitudinal phase space and current profile are re-shaped, and improvement in lasing performance can be realized. We present experimental studies at the LCLS of the beam shaping effects on the free electron laser performance.  
Dispersion Based Fresh Slice Scheme  
  • M.W. Guetg, Y.-C. Chao, F.-J. Decker, Y. Ding, A.S. Fisher, Z. Huang, A.A. Lutman, T.J. Maxwell
    SLAC, Menlo Park, California, USA
  This paper presents experimental studies of the dispersion based fresh slice scheme at LCLS. This scheme lead to pulse shortening resulting in pulse lengths below 10 fs. Careful orbit control allowed generating two colors with individual delay control and color separation of more than 3%. Unlike the dechirper based fresh slice scheme, the dispersion based fresh slice scheme does not require additional hardware. Another key benefit of this scheme is a strong spectral stability making the photon pulse energy independent of the electron energy jitter.