Author: Huang, Z.
Paper Title Page
TUPJE074 LCLS Injector Laser Modulation to Improve FEL Operation Efficiency and Performance 1813
 
  • S. Li, D.K. Bohler, W.J. Corbett, A.S. Fisher, S. Gilevich, Z. Huang, A. Li, D.F. Ratner, J. Robinson, F. Zhou
    SLAC, Menlo Park, California, USA
  • R.B. Fiorito, E.J. Montgomery
    UMD, College Park, Maryland, USA
  • H.D. Zhang
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • H.D. Zhang
    The University of Liverpool, Liverpool, United Kingdom
  
  In the Linear Coherent Light Source (LCLS) at SLAC, the injector laser plays an important role as the source of the electron beam for the Free Electron Laser (FEL). The injector laser strikes a copper photocathode which emits photo-electrons due to photo-electric effect. The emittance of the electron beam is highly related to the transverse shape of the injector laser. Currently the LCLS injector laser has hot spots that degrade the FEL performance. The goal of this project is to use adaptive optics to modulate the transverse shape of the injector laser, in order to produce a desired shape of electron beam. With a more controllable electron transverse profile, we can achieve lower emittance for the FEL, improve the FEL performance and operation reliability. We first present various options for adaptive optics and damage test results. Then we will discuss the shaping process with an iterative algorithm to achieve the desired shape, characterized by Zernike polynomial deconstruction.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPJE074  
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TUPMA003 Microbunching Phenomena in LCLS-II 1843
 
  • M. Venturini, C. F. Papadopoulos, J. Qiang
    LBNL, Berkeley, California, USA
  • Y. Ding, P. Emma, Z. Huang, G. Marcus, A. Marinelli, Y. Nosochkov, T.O. Raubenheimer, L. Wang, M. Woodley
    SLAC, Menlo Park, California, USA
  
  Funding: Work supported by DOE, in part under Contract No. DE-AC02-05CH11231 and through the LCLS-II project.
The microbunching instability has long been recognized as a potential limiting factor to the performance of X-ray FELs. It is of particular relevance in LCLS-II due, in part, to a layout that includes a long bypass beamline between the Linac and the undulators. Here we focus on two aspects of the instability that highlight the importance of 3D effects. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPMA003  
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TUPMA028 Feasibility Study for an X-ray FEL Oscillator at the LCLS-II 1897
 
  • T.J. Maxwell, J. Arthur, Y. Ding, W.M. Fawley, J.C. Frisch, J.B. Hastings, Z. Huang, J. Krzywinski, G. Marcus
    SLAC, Menlo Park, California, USA
  • W.M. Fawley
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • K.-J. Kim, R.R. Lindberg, D. Shu, Yu. Shvyd'ko, S. Stoupin
    ANL, Argonne, Ilinois, USA
  
  Funding: This work supported in part under US Department of Energy contract DE-AC02-76SF00515.
We show that a free-electron laser oscillator generating X-ray pulses with hard X-ray wavelengths of order 0.1 nm is feasible using the presently proposed FEL-quality electron beam within the space of existing LCLS-II infrastructure when combined with a low-loss X-ray crystal cavity. In an oscillator configuration driven by the 4 GeV energy electron beam lasing at the fifth harmonic, output x-ray bandwidths as small as a few meV are possible. The delivered average spectral flux is at least two orders of magnitude greater than present synchrotron-based sources with highly stable, coherent pulses of duration 1 ps or less for applications in Mössbauer spectroscopy and inelastic x-ray scattering. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPMA028  
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