Author: Amstutz, Ph.
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WEPAB016 Experience in Operating sFLASH With High-Gain Harmonic Generation 2596
 
  • J. Bödewadt, R.W. Aßmann, N. Ekanayake, B. Faatz, I. Hartl, T. Laarmann, C. Lechner, M.M. Mohammad Kazemi, A. Przystawik
    DESY, Hamburg, Germany
  • Ph. Amstutz, A. Azima, M. Drescher, W. Hillert, L.L. Lazzarino, Th. Maltezopoulos, V. Miltchev, T. Plath, J. Roßbach
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • K.E. Hacker, S. Khan, N.M. Lockmann, R. Molo
    DELTA, Dortmund, Germany
 
  sFLASH, the experimental setup for external seeding of free-electron lasers (FEL) at FLASH, has been operated in the high-gain harmonic generation (HGHG) mode. A detailed characterization of the laser-induced energy modulation, as well as the temporal characterization of the seeded FEL pulses is possible by using a transverse deflecting structure and an electron spectrometer. FEL saturation was reached for the 7th harmonic of the 266 nm seed laser. In this contribution, we present the latest experimental results.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB016  
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THPAB014 An Adaptive Mesh-Based Method for the Efficient Simulation of LSC-Driven Microbunching Gain in FEL Applications 3720
 
  • Ph. Amstutz
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • M. Vogt
    DESY, Hamburg, Germany
 
  Electron beams with high peak current as they are required for the operation of free-electron lasers (FELs) are often generated by means of a series of magnetic bunch compressors. In conjunction with a collective coherent force, e.g. longitudinal space-charge (LSC), bunch compressors can possibly cause a wavelength dependent amplification of initial density inhomogeneities, potentially to an extent detrimental to the operation of the FEL. A common model, consisting of LSC, acceleration (kicks), and magnetic chicanes (drift-type maps), is governed by a time-discrete Vlasov-Poisson system. Such systems have been successfully simulated using mesh based representations of the phase space density (PSD) and the method of characteristics for the update step. However, for the irregular and exotic PSDs, prevalent in FEL applications, a homogeneous high resolution discretization on a naive rectangular mesh can be prohibitively wasteful. Here we present an approach based on adaptive tree refinement that addresses the complexity of the PSDs and allows for the efficient simulation of LSC-driven micro-bunching in FELs.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB014  
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