Author: Dohlus, M.
Paper Title Page
MOP003 Concept for a Seeded FEL at FLASH2 1
  • C. Lechner, R.W. Aßmann, J. Bödewadt, M. Dohlus, N. Ekanayake, G. Feng, I. Hartl, T. Laarmann, T. Lang, L. Winkelmann, I. Zagorodnov
    DESY, Hamburg, Germany
  • A. Azima, M. Drescher, Th. Maltezopoulos, T. Plath, J. Roßbach, W. Wurth
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • S. Khan, T. Plath
    DELTA, Dortmund, Germany
  The free-electron laser (FEL) FLASH is a user facility delivering photon pulses down to 4 nm wavelength. Recently, the second FEL undulator beamline 'FLASH2' was added to the facility. Operating in self-amplified spontaneous emission (SASE) mode, the exponential amplification process is initiated by shot noise of the electron bunch resulting in photon pulses of limited temporal coherence. In seeded FELs, the FEL process is initiated by coherent seed radiation, improving the longitudinal coherence of the generated photon pulses. The conceptual design of a possible seeding option for the FLASH2 beamline envisages the installation of the hardware needed for high-gain harmonic generation (HGHG) seeding upstream of the already existing undulator system. In this contribution, we present the beamline design and numerical simulations of the seeded FEL.  
WEP005 Coaxial Coupler RF Kick in the PITZ RF Gun 1
  • Y. Chen, P. Boonpornprasert, J.D. Good, H. Huck, I.I. Isaev, M. Krasilnikov, A. Oppelt, H.J. Qian, Y. Renier, F. Stephan
    DESY Zeuthen, Zeuthen, Germany
  • W. Ackermann, H. De Gersem
    TEMF, TU Darmstadt, Darmstadt, Germany
  • M. Dohlus
    DESY, Hamburg, Germany
  • Q.T. Zhao
    IMP/CAS, Lanzhou, People's Republic of China
  We investigate a transverse RF kick induced by the transition between rectangular waveguide and coaxial line of the RF coupler in the 1.6-cell L-band normal conducting (NC) RF gun at the Photo Injector Test Facility at DESY, Zeuthen site (PITZ). A three-dimensional electromagnetic simulation shows the disturbed RF field distributions in the fundamental accelerating mode. Based on the 3D RF field map, an electron beam based characterization and quantification of the coaxial coupler RF kick in the PITZ gun is simulated. Preliminary results of the investigations are presented.  
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