Author: Emma, C.
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TUP092 XFEL Third Harmonic Statistics Measurement at LCLS 269
 
  • A. Halavanau, C. Emma, E. Hemsing, A.A. Lutman, G. Marcus, C. Pellegrini
    SLAC, Menlo Park, California, USA
  
  We investigate the statistical properties of the 6 keV third harmonic XFEL radiation at 2 keV fundamental photon energy at LCLS. We performed third harmonic self-seeding in the hard X-ray self-seeding chicane and characterized the attained non-linear third harmonic spectrum. We compare theoretical predictions with experimental results.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP092  
About • paper received ※ 20 August 2019       paper accepted ※ 29 August 2019       issue date ※ 05 November 2019  
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THP071 Progress in High Power High Brightness Double Bunch Self-Seeding at LCLS-II 726
 
  • A. Halavanau, F.-J. Decker, Y. Ding, C. Emma, Z. Huang, A.K. Krasnykh, J. Krzywiński, A.A. Lutman, G. Marcus, A. Marinelli, A. Ratti, D. Zhu
    SLAC, Menlo Park, California, USA
  • C. Pellegrini
    UCLA, Los Angeles, California, USA
  
  Funding: Work supported by the U.S. Department of Energy Contract No. DE-AC02-76SF00515.
We have previosuly shown that we can generate near TW, 15 fs duration, near transform limited X-ray pulses in the 4 to 8 keV photon energy range using the LCLS-II copper linac, two electron bunches, a 4-crystal monochromator/delay line and a fast transverse bunch kicker. The first bunch generates a strong seeding X-ray signal, and the second bunch, initially propagating off-axis, interacts with the seed in a tapered amplifier undulator, where it propagates on axis. In this paper, we investigate the design of the 4-crystal monochromator, acting also as an X-ray delay system, and of the fast kicker, in preparation of the implementation of the system in LCLS-II. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP071  
About • paper received ※ 20 August 2019       paper accepted ※ 26 August 2019       issue date ※ 05 November 2019  
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TUT01 Superradiance and Stimulated-Superradiant Emission of Bunched Electron Beams 288
 
  • A. Gover, R. Ianconescu
    University of Tel-Aviv, Faculty of Engineering, Tel-Aviv, Israel
  • C. Emma, P. Musumeci, C. Pellegrini, N.S. Sudar
    UCLA, Los Angeles, USA
  • A. Friedman
    Ariel University, Ariel, Israel
  • R. Ianconescu
    Shenkar College of Engineering and Design, Ramat Gan, Israel
  
  Funding: We acknowledge support of the Israel Science Foundation and the German Israeli Projects Foundation (DIP).
We outline the fundamental processes of coherent radiation emission from a bunched charged particles beam [1]. In contrast to spontaneous emission of radiation from a random electron beam that is proportional to the number of particles N, a pre-bunched electron beam emits spontaneously coherent radiation proportional to N2 through the process of (spontaneous) superradiance (SP-SR) (in the sense of Dicke’s [2]). The SP-SR emission of a bunched electron beam can be even further enhanced by a process of stimulated-superradiance (ST-SR) in the presence of a seed injected radiation field. These coherent radiation emission processes are presented in term of a radiation mode expansion model, applied to general free electron radiation schemes: Optical-Klystron, HGHG, EEHG, and coherent THz sources based on synchrotron radiation, undulator radiation or Smith-Purcell radiation. The general model of coherent spontaneous emission is also extended to the nonlinear regime - Tapering Enhanced Stimulated Superradiance (TESSA) [3], and related to the tapered wiggler section of seed-injected FELs. In X-Ray FELs these processes are convoluted with other effects, but they are guidelines for strategies of wiggler tapering efficiency enhancement.
[1] A. Gover et al., Rev. Mod. Phys. https://arxiv.org/abs/1810.07566v3 (2019)
[2] R. H. Dicke, Physical Review 93, 99 (1954)
[3] N. Sudar et al., P.R.L. 117, 174801 (2016) 		 
slides icon Slides TUT01 [11.391 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUT01  
About • paper received ※ 20 August 2019       paper accepted ※ 29 August 2019       issue date ※ 05 November 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)