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Rossbach, J.

Paper Title Page
MOPPH053 Simulation Studies on the Self-Seeding Option at FLASH 162
 
  • V. Miltchev, J. Rossbach
    Uni HH, Hamburg
  • B. Faatz, R. Treusch
    DESY, Hamburg
  
  In order to improve the temporal coherence of the radiation generated by FLASH, a two-stage seeding scheme* is presently being realized. It consists of two undulator stages and a magnetic chicane and a monochromator located between them. In this contribution we investigate various configurations of the electron optics of the seeding set-up. The optimization of the lattice in the first seeding stage and the parameters of the magnetic chicane will be discussed. Simulation results for the performance of the seeded FEL at different resonant wavelengths will be presented.

* J. Feldhaus et. al. "Possible application of X-ray optical elements for reducing the spectral bandwidth of an X-ray SASE FEL". Optics Communications, Volume 140, Pages 341-352

 
THPPH018 Single-Shot Longitudinal Diagnostics with THz Radiation at the Free-Electron Laser FLASH 594
 
  • H. Delsim-Hashemi, J. Rossbach, P. Schmüser
    Uni HH, Hamburg
  • O. Grimm, H. Schlarb, B. Schmidt
    DESY, Hamburg
  • A. F.G. van der Meer
    FOM Rijnhuizen, Nieuwegein
  
  The longitudinal charge distribution in the electron bunches has a strong impact on the lasing process in a SASE-type FEL. The investigation of the longitudinal charge distribution in the electron bunches with very high resolution and on a bunch-by-bunch basis is enabled by a novel spectrometer which is based on diffraction gratings and multichannel signal detection. Measurements of coherent transition radiation with this spectrometer in both the scanning mode and the single-shot mode are presented. Structures in the electron bunches as short as 10 fs have been observed. Correlations between the measured FEL pulse energies and the signals in different wavelength channels of the single-shot spectrometer have been established. These data will be utilized to fine-tune the parameters of the bunch compression system at FLASH in order to optimize the gain in the SASE process.  
THPPH019 Investigations of Longitudinal Beam Properties at the Photoinjector Test Facility in Zeuthen 597
 
  • J. R. Roensch, J. Rossbach
    Uni HH, Hamburg
  • G. Asova, J. W. Baehr, H.-J. Grabosch, S. Khodyachykh, S. A. Korepanov, M. Krasilnikov, A. Oppelt, B. Petrosyan, S. Riemann, L. Staykov, F. Stephan
    DESY Zeuthen, Zeuthen
  • D. Lipka, F. Marhauser, R. Richter
    BESSY GmbH, Berlin
  • A. P. Onuchin
    BINP SB RAS, Novosibirsk
  
  The goal of the Photoinjector Test Facility at DESY in Zeuthen (PITZ) is to test and optimise electron guns for FELs like FLASH at DESY in Hamburg. In 2005 the setup was extended by a booster cavity. In order to measure longitudinal and transverse beam properties in the range between 5 to 40 MeV/c, a viewport after the booster cavity was developed. It contains several radiators. One of them is Silica aerogel used as Cherenkov radiator for the measurement of the longitudinal electron distribution with a streak camera. Design considerations are presented and maybe first measurement results are available. The longitudinal distributions after the booster for different beam parameters are compared to the distributions before the booster.