Author: Maxwell, T.J.
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TUP030 Time Dependent Study for an X-ray FEL Oscillator at LCLS-II 433
  • J. Zemella
    DESY, Hamburg, Germany
  • W.M. Fawley, T.J. Maxwell
    SLAC, Menlo Park, California, USA
  • R.R. Lindberg
    ANL, Argonne, Illinois, USA
  The LCLS-II with its high repetition rate and high quality beam will be capable of driving an X-ray free electron laser oscillator at higher harmonics in the hard X-ray regime (0.1 nm). The oscillator consists of a low loss X-ray crystal cavity using diamond Bragg crystals with meV bandwidth. The expected average spectral flux has been estimated to be 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. A more detailed study of the start up of a fifth-harmonic X-ray FEL oscillator at LCLS-II will be presented with full, time-dependent simulations.  
poster icon Poster TUP030 [0.619 MB]  
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TUP070 Energy Jitter Minimization at LCLS 523
  • L. Wang, A.L. Benwell, A. Brachmann, W.S. Colocho, F.-J. Decker, Z. Huang, T.J. Maxwell, T. Tao, J.L. Turner
    SLAC, Menlo Park, California, USA
  The energy jitters of the electron beam can affects the FEL in self-seeded modes if the jitter is large compared to the FEL parameter. We work in multiple ways to reduce the jitters, including hardware improvement, optimization linac set-up. This paper discusses the optimization of linac set-up. The solutions always suggest that we can largely reduce the energy jitter from a weak compression at BC1 and a stronger compression at BC2. Meanwhile a low beam energy at BC2 also reduce the energy jitter, which is confirmed by the experiment. The results can be explained by a simple model. Experimental results are also presented, demonstrating better than 20% and 40% relative energy jitter reduction for 13.6 and 4 GeV linac operation, respectively.  
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Progress Towards an X-ray FEL Oscillator  
  • K.-J. Kim, T. Kolodziej, R.R. Lindberg, D. Shu, Yu. Shvyd'ko, S. Stoupin
    ANL, Argonne, Ilinois, USA
  • J. Arthur, Y. Ding, W.M. Fawley, J.C. Frisch, J.B. Hastings, Z. Huang, J. Krzywinski, G. Marcus, T.J. Maxwell
    SLAC, Menlo Park, California, USA
  Funding: Work at ANL supported under US Department of Energy contract DE-AC02-76SF00515 and at SLAC by the U.S. Department of Energy, Office of Science, under Contract No. DE-ACO2-O6CH11357
Issues and progress in R&D toward realizing an X-ray FEL oscillator will be discussed, including electron injector optimization, X-ray power density evolution on Bragg crystals throughout the lasing process, experimental efforts for testing radiation damage, evaluating the performance of compound refractive lenses (CRLs) as the focusing elements, and the basic considerations for mechanical layout. These will be discussed in the context of a concrete implementation scheme [*] using the 4 GeV superconducting linac to be constructed at the LCLS-II. Time-dependent simulations of harmonic XFELO performance is discussed in another contribution to this conference by Zemella, et al.
[*] T. J. Maxwell et al., Feasibility study for an X-ray free electron laser oscillator, IPAC 2015, Richmond, Virginia, USA
slides icon Slides WEB03 [6.452 MB]  
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