Mini-Workshop on Commissioning of
X-Ray Free-Electron Lasers
 April 18-22, 2005, DESY Zeuthen, Germany

Work Package 3: Analysis of Simulated X-Ray Pulses
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Coordinators:

S. Reiche (Chair), UCLA +1-310-206-4540
P. Ilinski, DESY +49-40-8998-1730
H.-D. Nuhn, SLAC +1-650-926-2275

Ideas:

The numerical modeling of the X-ray radiation pulse allows for the investigation of measurement techniques and the signal strength and quality at the location of the detector. In these virtual experiments the results of the simulated measurements can be compared to the values directly extracted from the radiation pulse. The numerical simulation of the XFEL X-ray pulse is an invaluable tool to model FEL pulse propagation along the beamline, to interpret x-ray diagnostics measurements and to predict the conditions of future experiments. Of special consideration is the simulation of following aspects in the commission and operation phase of an X-ray FEL:
  1. Measurement of the transverse coherence. Based on the output of an FEL simulation, the wavefronts of multiple slices should be propagated through the X-ray beamline down to the experimental station, where the transverse coherence is measured. The initial wavefront distribution can be downloaded from this website (see below for more info and format)
  2. Similar to the transverse coherence, the simulation output can be used to predict the radiation pulse length and/or coherence length.
  3. The aperture limit of the undulator vacuum chamber and X-ray transport beam line will alter the properties of the spontaneous radiation, seen by the detector. Part of the radiation is reflected or absorbed and the spectrum becomes wider at the detector location. Modeling strategies should be presented and discussed as well as the consequence of possible radiation damage to the vacuum chamber and undulator by the reflected X-rays.
  4. And early detection of the FEL signal is essential to the successful commission of the FEL. However the FEL signal only gradually emerges from the spontaneous background. The expected radiation power, degree of coherence and FEL signal spatial and spectral distributions in the start-up regime should be presented in comparison to the full spontaneous background signal.

Information of the supplied wavefronts:

The single wavefront is sampled on a 139×139 grid of 16 byte long complex numbers (or alternative of pairs of 8 byte long real numbers), corresponding to the real and imaginary part of the wavefront amplitude at the grid points. The total file size is 139×139×16 bytes = 309,136 bytes. The transverse grid has a grid spacing of 7.481 microns and the reference wavelength is 1.5 Å. The full profile consisting of a series of wavefronts is no longer posted. The data can still be obtained from Sven Reiche (reiche@ucla.edu).

Presentation Equipment:

Provisions for presenting talks from a CD or a PC laptop are available as wells as using the old overhead projector.

Documents:

Icon  Name                    Last modified      Size  Description
[DIR] Parent Directory                             -   
[   ] lcls_wavefront.single   17-Feb-2005 16:38  302K
Content Owner: S. Reiche, SLAC
Page Editor: H.-D. Nuhn, SLAC

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