Keyword: free-electron-laser
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TUPRB062 Coherence Time Characterization for Self-Amplified Spontaneous Emission Free-Electron Lasers electron, FEL, laser, radiation 1820
  • G. Zhou, Y. Jiao, J.Q. Wang
    IHEP, Beijing, People’s Republic of China
  • T.O. Raubenheimer, J. Wu
    SLAC, Menlo Park, California, USA
  • C.-Y. Tsai
    HUST, Wuhan, People’s Republic of China
  • C. Yang
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
  One of the key challenges in scientific researches based on free-electron lasers (FELs) is the characterization of the coherence time of the ultra-fast hard x-ray pulse, which fundamentally influences the interaction process between x-ray and materials. Conventional optical methods, based on autocorrelation, is very difficult to realize due to the lack of mirrors. Here, we experimentally demonstrate a conceptually new coherence time characterization method and a coherence time of 174.7 attoseonds has been measured for the 6.92 keV FEL pulses at Linac Coherent Light Source. In our experiment, a phase shifter is adopted to control the cross-correlation between x-ray and microbunched electrons. This approach provides critical temporal coherence diagnostics for x-ray FELs, and is decoupled from machine parameters, applicable for any photon energy, radiation brightness, repetition rate and FEL pulse duration, etc.
The work was supported by the US Department of Energy (DOE) under contract DE-AC02-76SF00515 and the US DOE Office of Science Early Career Research Program grant FWP-2013-SLAC-100164.
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About • paper received ※ 01 May 2019       paper accepted ※ 28 May 2019       issue date ※ 21 June 2019  
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TUPRB096 Test of an X-ray Cavity using Double-Bunches from the LCLS Cu-Linac FEL, cavity, electron, laser 1887
  • K.-J. Kim, L. Assoufid, R.R. Lindberg, X. Shi, D. Shu, Yu. Shvyd’ko, M. White
    ANL, Argonne, Illinois, USA
  • F.-J. Decker, Z. Huang, G. Marcus, T.O. Raubenheimer, D. Zhu
    SLAC, Menlo Park, California, USA
  Funding: This work is supported by U.S. DOE, Office of Science, Office of BES, under Contract No. DE-AC02-06CH11357 (ANL) and DE-AC02-76SF00515 (SLAC).
We discuss a proposal to test the operation of an X-ray cavity consisting of Bragg reflectors. The test will con-stitute a major step demonstrating the feasibility of either an X-ray regenerative amplifier FEL or an X-ray FEL Oscillator. These cavity-based X-ray FELs will provide the full temporal coherence lacking in the SA-SE FELs. An X-ray cavity of rectangular path will be constructed around the first seven LCLS-II undulator units. The Cu-linac will produce a pair of electron bunches separated by the cavity-round-trip distance during each linac cycle. The X-ray pulse produced by the first bunch is deflected into the cavity and returns to the undulator where it is amplified due to the presence of the second bunch. The key challenges are: the preci-sion of the cavity mechanical construction, the quality of the diamond crystals, and the electron beam stability. When the LCLS-II super-conducting linac becomes available, the cavity can then be used for high-repetition rate studies of the X-ray RAFEL and XFELO concepts.
DOI • reference for this paper ※  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEXXPLM1 Amplified Emission of a Soft-X Ray Free-Electron Laser Based on Echo-Enabled Harmonic Generation FEL, laser, electron, experiment 2230
  • E. Allaria, L. Badano, G. De Ninno, S. Di Mitri, B. Diviacco, W.M. Fawley, N.S. Mirian, G. Penco, P. Rebernik Ribič, S. Spampinati, C. Spezzani, M. Trovò
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • G. De Ninno
    University of Nova Gorica, Nova Gorica, Slovenia
  • E. Ferrari, E. Prat
    PSI, Villigen PSI, Switzerland
  • D. Garzella
    CEA, Gif-sur-Yvette, France
  • V. Grattoni
    DESY, Hamburg, Germany
  • E. Hemsing
    SLAC, Menlo Park, California, USA
  • M.A. Pop
    MAX IV Laboratory, Lund University, Lund, Sweden
  • E. Roussel
    PhLAM/CERLA, Villeneuve d’Ascq, France
  • D. Xiang
    Shanghai Jiao Tong University, Shanghai, People’s Republic of China
  We report the first evidence of substantial gain in a soft-X ray Free Electron Laser (FEL) based on Echo-Enabled Harmonic Generation (EEHG). The experiment was focused on harmonics 36 (~7.3nm) and 45 (5.8 nm) and clearly demonstrated the expected EEHG capability of generating powerful and coherent FEL pulses, with strongly reduced sensitivity to electron-beam fluctuations. The experiment was carried out at FERMI, the seeded FEL user facility at Elettra-Sincrotrone Trieste.  
slides icon Slides WEXXPLM1 [11.410 MB]  
DOI • reference for this paper ※  
About • paper received ※ 17 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPRB048 Design, Fabricate, and Tuning of X-Band Deflecting Structure for CERN simulation, cavity, GUI, electron 2915
  • J.H. Tan, W. Fang, Q. Gu, X.X. Huang, Z.T. Zhao
    SSRF, Shanghai, People’s Republic of China
  A 20-cell x-band deflecting structure for CERN has been finished, and now is under high power conditioning at XBOX of CERN.  
DOI • reference for this paper ※  
About • paper received ※ 14 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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THYPLM1 Development of the Vertically Polarizing Hard X-Ray Undulator Segments for the Linear Coherent Light Source Upgrade (LCLS-II) Project undulator, photon, operation, electron 3408
  • M. Leitner, D. Arbelaez, J.N. Corlett, A.J. DeMello, L. Garcia Fajardo, D. Leitner, S. Marks, K.A. McCombs, T. Miller, D.V. Munson, J. Niu, K.L. Ray, D.A. Sadlier, D. Schlueter, E.J. Wallén
    LBNL, Berkeley, California, USA
  • H. Bassan, D.E. Bruch, D.S. Martinez-Galarce, H.-D. Nuhn, M. Rowen, Z.R. Wolf
    SLAC, Menlo Park, California, USA
  • C.W. Chen
    NSRRC, Hsinchu, Taiwan
  Funding: Work supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
The Linear Coherent Light Source II (LCLS-II) is a free electron laser facility currently in its final construction stage at Stanford Linear Accelerator Center. The project includes two variable-gap, hybrid-permanent-magnet undulator lines: A soft x-ray undulator line with 21 undulator segments optimized for a photon energy range from 0.2 keV to 1.3 keV and a hard x-ray undulator line with 32 undulator segments designed for a photon energy range from 1.0 keV to 25.0 keV. This paper focuses on the design, development, and performance of the hard x-ray undulator line which utilizes uniquely-developed, vertically-polarizing undulators. To fully compensate the magnetic force throughout the entire gap range these devices incorporate non-linear spring systems which permit the construction of relatively compact undulators. However, significant magnetic field repeatability challenges have been encountered during prototyping of this novel design. The paper describes the innovative design improvements that were implemented which lead to reaching the LCLS-II required performance. These final design solutions can also be advantageous improving the operation of any future undulator design.
slides icon Slides THYPLM1 [28.498 MB]  
DOI • reference for this paper ※  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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