Author: Bane, K.L.F.
Paper Title Page
High-Flux, Fully Coherent X-Ray FEL Oscillator  
  • K.-J. Kim, S.P. Kearney, T. Kolodziej, R.R. Lindberg, X. Shi, D. Shu, Yu. Shvyd'ko
    ANL, Argonne, Illinois, USA
  • K.L.F. Bane, Y. Ding, P. Emma, W.M. Fawley, J.B. Hastings, Z. Huang, J. Krzywinski, G. Marcus, T.J. Maxwell
    SLAC, Menlo Park, California, USA
  • V.D. Blank, S. Terentiev
    TISNCM, Troitsk, Russia
  • W.M. Fawley
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • C. Grizolli
    LNLS, Campinas, Brazil
  • W. Qin
    PKU, Beijing, People's Republic of China
  • S. Stoupin
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • J. Zemella
    DESY, Hamburg, Germany
  Funding: The ANL part of this work is supported by the U.S. DOE Office of Science under Contract No. DE-AC02-06CH11357 and the SLAC part under contract No. DE-AC02-76SF00515.
By optimizing the parameters of the accelerator, undulator, and the optical cavity, an XFELO driven by an 8-GeV superconducting linac is predicted to produce 10zEhNZeHn photons per pulse at the important photon energies around 14.4 keV.* This is an order of magnitude larger than that in previous designs.** With a BW of 3 meV (FWHM), rep rate of 1 MHz, and taking into account the full coherence, the spectral brightness is then 2×1026 photons per (mm2mr2 0.1\% BW), which is higher than any other source currently operating or anticipated in the future. Experiments at APS beam lines have shown that a high-quality diamond crystal can survive the power density (~15 kW/mm2) expected at the XFELO intra-cavity crystals preserving the high reflectivity.*** The compound refractive lenses can serve as the focusing element. Adding an XFELO to the suite of other FEL sources will, at a minor incremental cost but with a major scientific payoff, significantly expand the scientific capabilities at superconducting linac-based XFEL facilities, such as the European XFEL, the proposed LCLS-II High Energy upgrade and the XFEL project in Shanghai.
* W. Qin et al., this conference.
** R.R. Lindberg et al., Phys. Rev. ST Accel. Beams, vol 14, 403 (2011).
*** T. Kolodziej et al., this conference.
Start-to-End Simulations for an X-Ray FEL Oscillator at the LCLS-II and LCLS-II-HE  
  • W. Qin, K.L.F. Bane, Y. Ding, Z. Huang, G. Marcus, T.J. Maxwell
    SLAC, Menlo Park, California, USA
  • S. Huang, K.X. Liu
    PKU, Beijing, People's Republic of China
  • K.-J. Kim, R.R. Lindberg
    ANL, Argonne, Illinois, USA
  The proposed high repetition-rate electron beam from the LCLS-II and LCLS-II High Energy (LCLS-II-HE) upgrade are promising sources as drivers for an X-ray FEL Oscillator (XFELO) operating at both the harmonic and fundamental frequencies. In this contribution we present start-to-end simulations for an XFELO operating at the fifth harmonic with 4 GeV LCLS-II beam and at the fundamental with 8 GeV LCLS-II-HE beam. The electron beam longitudinal phase space is optimized by shaping the photoinjector laser and adjusting various machine parameters. The XFELO simulations show that high-flux output radiation pulses with 1010 photons and 3 meV (FWHM) spectral bandwidth can be obtained with the 8 GeV configuration.  
Recent Developments and Plans for Two Bunch Operation with up to 1 μs Separation at LCLS  
  • F.-J. Decker, K.L.F. Bane, W.S. Colocho, A.A. Lutman, J.C. Sheppard
    SLAC, Menlo Park, California, USA
  Funding: Work supported by U.S. Department of Energy, Contract DE-AC02-76SF00515.
To get two electron bunches with a separation of up to 1 microsecond at the Linac Coherent Light Source (LCLS) is important for LCLS-II developments. Two lasing bunches up to 220 ns have been demonstrated. Many issues have to be solved to get that separation increased by a factor of 5. The typical design and setup for one single bunch has to be questioned for many devices: RF pulse widths have to be widened, BPMs diagnostic can see only one bunch or a vector average, feedbacks have to be doubled up, the main Linac RF needs to run probably un-SLEDed, and special considerations have to be done for the Gun and L1X RF.
Beam Shaping to Improve the Free-Electron Laser Performance at the Linac Coherent Light Source  
  • Y. Ding, K.L.F. Bane, W.S. Colocho, F.-J. Decker, P. Emma, J.C. Frisch, M.W. Guetg, Z. Huang, R.H. Iverson, J. Krzywinski, H. Loos, A.A. Lutman, T.J. Maxwell, H.-D. Nuhn, D.F. Ratner, J.L. Turner, J.J. Welch, F. Zhou
    SLAC, Menlo Park, California, USA
  A new operating mode has been developed for the Linac Coherent Light Source (LCLS) in which we shape the longitudinal phase space of the electron beam. This mode of operation is realized using a horizontal collimator located in the middle of the first bunch compressor to truncate the head and tail of the beam. With this method, the electron beam longitudinal phase space and current profile are re-shaped, and improvement in lasing performance can be realized. We present experimental studies at the LCLS of the beam shaping effects on the free electron laser performance.