Author: Liu, B.
Paper Title Page
WEPAF043 Commissioning and Long-Term Results of a Fully-Automated Pulse-Based Optical Timing Distribution System at Dalian Coherent Light Source 1909
 
  • H.P.H. Cheng, A. Berlin, E. Cano, A. Dai, J. Derksen, D. Forouher, W. Nasimzada, M. Neuhaus, P. Schiepel, E. Seibel, K. Shafak
    Cycle GmbH, Hamburg, Germany
  • Z. Chen, H.L. Ding, Z.G. He, Y.H. Tian, G.R. Wu
    DICP, Dalian, People's Republic of China
  • F.X. Kärtner
    Deutsches Elektronen Synchrotron (DESY) and Center for Free Electron Science (CFEL), Hamburg, Germany
  • B. Liu, X.Q. Liu
    SINAP, Shanghai, People's Republic of China
  
  New generation light sources such as X-ray free-electron lasers* and attoscience centers** require high demand for timing synchronization, on the order of few femtoseconds or below, to generate ultrashort X-ray pulses that enables attosecond temporal and subatomic spatial resolution. The challenge in achieving this scientific dream lies in part in a reliable, high-precision timing distribution system that can synchronize various optical and microwave sources across multi-km distances with good long-term stability. It was shown that the pulsed-optical timing distribution system can deliver sub-fs long-term timing precision between remotely synchronized lasers and microwave sources in laboratory environment.*** We present the latest results from the commissioning of China's first multi-link pulse-based optical timing distribution system (TDS) installed at Dalian Coherent Light Source. Long term operating results of the fully-automated polarization-maintaining TDS, as well as lessons learned and recommendations for future improvements, are presented, including performance of the timing-stabilized PM fiber links, microwave end-stations and ultrafast laser synchronization end-stations.
*http://www.xfel.eu/news/2017/europeanxfelgeneratesitsfirstlaserlight
**G. Mourou and T. Tajima, Science, 331, pp. 41-42, 2011.
***M. Xin et al., Light Sci. Appl., 6, e16187, 2017.
 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF043  
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THPMK068 High degree circular polarization at x-ray self-seeding FELs with crossed-planar undulators 4453
 
  • K. Li, H.X. Deng, Z.F. Gao, B. Liu, D. Wang
    SINAP, Shanghai, People's Republic of China
  
  Funding: Work was supported by the National Natural Science Foundation of China (11775293), the National Key Research and Development Program of China (2016YFA0401900).
The crossed undulator configuration for a high-gain free-electron laser (FEL) is well-known for the ability of versatile polarization control. However, the degree of polarization is very sensitive to power and phase between the two stages of crossed undulators. In this poster, we introduce the generation of high degree circular polarization hard x-ray FEL with crossed-planar undulator seeded by self-seeding. The reverse taper and taper undulator technology are employed for improving its performance. With the combination of high degree (>95%) circular polarization and flexibility of polarization switching, this scheme might be useful for some scientific research in the future. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK068  
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THPMK069 Design of the Beam Switchyard of a Soft X-ray FEL User Facility in Shanghai 4456
 
  • S. Chen, H.X. Deng, C. Feng, B. Liu, D. Wang, R. Wang
    SINAP, Shanghai, People's Republic of China
  
  A soft X-ray FEL user facility, which is based on the existing test facility located in the Zhangjiang Campus of SINAP, is under construction. Two undulator lines will be installed parallelly in the undulator hall and their electron beams are served by a 1.5 GeV linac. For simultaneous operation of the two undulator lines, a beam distribution system should be used to connect the linac and the undulator lines. In this paper, the physics design of this beam distribution system will be presented and also the beam dynamic issues will be discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK069  
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THPML065 Preliminary Results of the Bunch Arrival-Time Monitor at SXFEL 4787
 
  • J.G. Wang, B. Liu
    SINAP, Shanghai, People's Republic of China
  
  Based on an electro-optical intensity modulation detection scheme, a Bunch Arrival-time Monitor (BAM) is under study at Shanghai soft X-ray Free Electron Laser (SXFEL) to meet the high-resolution requirements of the measurement of bunch arrival time. The first BAM is installed and is being tested at the SXFEL upstream of the first short undulator (modulator) near the seed laser injection point. In this paper, we present the basic working principle, the design of the BAM system and report the preliminary test results.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML065  
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