Author: Anisimov, P.M.
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MOC01 Regenerative Amplifier FEL - from IR to X-Rays 20
  • D.C. Nguyen, P.M. Anisimov, C.E. Buechler, Q.R. Marksteiner, R.L. Sheffield
    LANL, Los Alamos, New Mexico, USA
  The Regenerative Amplifier FEL (RAFEL) feeds back a small fraction of the radiation exiting a high-gain undulator as the seed for the next pass, and achieves narrow linewidth and saturation in a few passes. For the IR RAFEL, we used an optical cavity with annular mirrors to reinject ~10% of the IR radiation back into a two-meter undulator [1]. Since then, a number of researchers have proposed RAFEL and XFELO to achieve full temporal coherence in VUV and X-ray FELs [2-5]. For the XFELO, symmetric Bragg backscattering off high-quality diamond crystals can provide very high reflectivity for the XFELO cavity [6]. The required reflectivity for a RAFEL feedback cavity is much lower than the XFELO. We show that 6% feedback is sufficient for the X-ray RAFEL at 9.8 keV to saturate and achieve 0.5-eV bandwidth. We discuss options to out-couple more than ~50% of the RAFEL intra-cavity power and discuss challenges associated with X-ray absorption in the out-coupler.
[1] D. Nguyen et al. NIMA 429 125 (1999)
[2] B. Faatz et al. NIMA A429 424 (1999)
[3] Z. Huang et al. PRL 96 144801 (2006)
[4] B.W.J. McNeil et al. NJP 9 239 (2007)
[5] G. Marcus et al. FEL17 MOP061 (2017)
[6] K. Kim et al. PRL 100 244802 (2008)
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About • paper received ※ 21 August 2019       paper accepted ※ 28 August 2019       issue date ※ 05 November 2019  
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Using an E-SASE Compression to Suppress Microbunch Instability and Resistive-Wall Wake Effects  
  • P.M. Anisimov
    LANL, Los Alamos, New Mexico, USA
  Funding: Research presented in this presentation was supported by the Laboratory Directed Research and Development program of Los Alamos National Laboratory under project number 20180535ECR.
High brightness electron sources, such as photo injectors, deliver electron beams with a few Ampere peak currents yet high energy X-ray free-electron lasers require electron beams with >3kA peak currents to operate. In order to bridge this gap, a 100x beam compression that does not reduce the brightness of an electron beam has to take place. We will present our study of an E-SASE based compression scheme aimed at satisfying the requirements of high energy X-ray free electron lasers regarding electron beam currents, energy spreads and emittances. The E-SASE compression is based on a laser modulation of an electron beam energy and subsequent compression in a small magnetic chicane, which results in a train of high current bunches that are synchronized to the external laser and could be used in pump-probe experiments. A unique time profile of an electron beam is expected to suppress the resistive-wall wake effects.
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