Author: Feng, Y.
Paper Title Page
WEODB101 X-ray Spectra and Peak Power Control with iSASE 2068
  • J. Wu, F.-J. Decker, Y. Feng, J. Krzywinski, H. Loos, A.A. Lutman, A. Marinelli, H.-D. Nuhn, C. Pellegrini, D.F. Ratner, D.H. Zhang, D. Zhu
    SLAC, Menlo Park, California, USA
  Funding: Work is supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contract DE-AC02-76SF00515.
We report the first measurement of spectral line-width reduction in a self-amplified spontaneous emission (SASE) X-ray free-electron laser (FEL) obtained by introducing repeated delays of the electron bunch with respect to the radiation field pulse. The improved longitudinal coherence obtained by this method reduces the intensity spiking effect characteristic of a SASE FEL. The electron-photon delays introduced along the FEL undulator mix the spikes phase and amplitude, increasing the cooperation length and generating a smaller bandwidth than in the conventional SASE mode of operation of an FEL. We call this mode of operation, based on repeated electron-photon delays, ‘‘improved SASE'' (iSASE). We also show with theoretical and simulation analysis that in the iSASE mode it is possible to choose the separation and magnitude of the delays to obtain a nearly transform limited X-ray pulse. This analysis is carried out using a time dependent, one-dimensional model and with GENESIS numerical simulation, including three-dimensional effects.
slides icon Slides WEODB101 [7.647 MB]