Author: Otake, Y.
Paper Title Page
WEOBB01 Design and Performance of the Optical Fiber Length Stabilization System for SACLA 1906
 
  • H. Maesaka, T. Ohshima, Y. Otake
    RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
  • S. Matsubara
    JASRI/SPring-8, Hyogo, Japan
  
  The x-ray free electron laser facility, SACLA, requires timing synchronization accuracies of less than 50 fs for acceleration rf components and less than 10 fs for pump-and-probe user experiments. Although a stable timing distribution system with optical fiber cables was constructed*, a timing drift of more than 100 fs has been observed after the transmission of about 100 m**. In order to suppress optical fiber length drift, we developed and installed an optical fiber length stabilization system with a Michelson interferometer. A frequency-stabilized laser with a wavelength of 1.5 um is transmitted together with a timing signal and it is reflected back to the interferometer. The length signal from the interferometer is fed back to a fiber stretcher for fiber length control. A prototype system showed that the length of a 1km-long optical fiber in a feedback loop was stabilized within 0.1 um corresponding to 0.5 fs. From this result, a timing accuracy improvement of pump-and-probe experiments can be expected. In this presentation, the design and basic performance of the optical fiber length stabilization system and the operational experience at SACLA will be reported.
* H. Maesaka et al., Proceedings of FEL’08, 352 (2008).
** H. Maesaka et al., Proceedings of FEL’12, 325 (2012).
 		 
slides icon Slides WEOBB01 [2.673 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEOBB01  
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THPRO016 Stable Generation of High Power Self-seeded XFEL at SACLA 2888
 
  • T. Inagaki, N. Adumi, T. Fukui, T. Hara, Y. Inubushi, T. Ishikawa, H. Kimura, R. Kinjo, H. Maesaka, Y. Otake, H. Tanaka, T. Tanaka, K. Togawa, M. Yabashi
    RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
  • S. Goto, T.K. Kameshima, T. Ohata, K. Tono
    JASRI/SPring-8, Hyogo, Japan
  • T. Hasegawa, S. Tanaka
    SES, Hyogo-pref., Japan
  • A. Miura, H. Ohashi, H. Yamazaki
    Japan Synchrotron Radiation Research Institute (JASRI/SPring-8), Hyogo, Japan
  
  A self-seeded XFEL system using a transmitted beam under Bragg diffraction has been developed at the first compact XFEL facility SACLA in order to generate a brilliant single-mode XFEL with high temporal coherence. High stability and unique beam characteristics of SACLA should significantly contribute to achieve reliable, high-quality seeded XFEL operation. In particular, the short-pulse property that has been achieved in routine operation enables us to switch SASE and seeded mode quickly, without changing the electron beam parameters. This is also useful for delivering different modes to multiple beamlines simultaneously. In the test experiments carried out in autumn 2013, spectral narrowing was observed at 10 keV using diamond 400 reflection. Systematic optimization on beam properties is now in progress towards experimental use of seeded XFELs in summer 2014. This talk gives the overview of the plan, achieved results and ongoing R&D.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO016  
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