06 Beam Instrumentation, Controls, Feedback, and Operational Aspects
T24 Timing and Synchronization
Paper Title Page
WEPAF007 A Scheme for Asynchronous Operation of the APS-U Booster Synchrotron 1823
  • U. Wienands, T.G. Berenc, T. Fors, F. Lenkszus, N. Sereno, G.J. Waldschmidt
    ANL, Argonne, Illinois, USA
  Funding: Work supported by US DOE
The APS-U 6-GeV MBA storage ring will have 42 pm beam emittance and relatively tight acceptance. This requires limiting the beam emittance out of the Booster synchrotron which is achieved by operating the Booster off-momentum, thus manipulating the damping partitions. However, the much higher charge for the APS-U strongly favors injecting on momentum into the Booster for maximum acceptance. An rf-frequency ramping scheme is proposed to allow injecting on momentum and then moving the beam off momentum. The ramp is adjusted from cycle to cycle to vary the total time taken by the beam from injection to extraction, thus aligning the Booster bunch with any chosen MBA storage ring bucket. The two rf systems will not be locked at any time of the cycle. The proposed scheme is compatible with the existing synchronization of the APS injector cycle to the 60-Hz line voltage which induces a variation in the start time of the acceleration cycle. The scheme removes the need to realign the Booster ring for total path length while optimizing its operation for high charge acceleration. A ferrite tuner is being considered for dynamic tuning of the rf cavities.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF007  
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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.
**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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WEPAL035 The Synchronization System of the Thomx Accelerator 2243
  • N. Delerue, V. Chaumat, R. Chiche, N. ElKamchi, H. Monard, F. Wicek
    LAL, Orsay, France
  • B. Lucas
    CNRS LPGP Univ Paris Sud, Orsay, France
  Funding: CNRS and ANR
The ThomX compact light source uses a 50 MeV ring to produce X-rays by Compton scattering. For historical reasons the linac and the ring could not operate at harmonic frequencies of each other. A heterodyne synchronization system has been designed for this accelerator. This synchronization is based on mixing the two RF frequencies to produce an heterodyne trigger signal and that is then distributed to the users. Bench tests of the system has demonstrated a jitter of less than 2 ps. We describe here this synchronization system.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL035  
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WEPAL036 Implementation of CSNS RCS Beam Injection and Extraction Modes in Timing System 2247
  • P. Zhu, M.Y. Huang, D.P. Jin, G. Lei, G.L. Xu, Y.L. Zhang
    IHEP, Beijing, People's Republic of China
  • L. Wang
    CSNS, Guangdong Province, People's Republic of China
  Funding: Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China; Dong guan Neutron Science Center, Dong guan 523803, China
Based on the physical design of the accelerator and the demand of the beam research, we designed four RCS beam injection modes and two RCS beam extraction modes, each of which corresponds to a series of specific timing for the accelerator. RCS beam injection and extraction modes are implemented on "VME + customized boards" hardware platform. In this paper, we will introduce the design and implementation of RCS beam injection and extraction modes as well as the RCS timing requirements and implementation in detail.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL036  
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WEPAL040 High Precision Synchronization Development for HiRES, the Ultrafast Electron Diffraction Beamline at LBNL 2262
  • Y. Yang, K.M. Baptiste, M. Betz, L.R. Doolittle, Q. Du, D. Filippetto, G. Huang, F. Ji
    LBNL, Berkeley, California, USA
  Precise synchronization between the laser and electron is critical for the pump-probe experiments in the HiRES Ultrafast Electron Diffraction facility. We are upgrading the LLRF and laser control system, which ultimately aims at a synchronization below 50 fs RMS between the pump laser pulse and electron probe at the sample plane. Such target poses tight requirements on the RF field stability both in amplitude and phase, and on the synchronization between the RF field and the laser repetition rate. We are presently developing a new LLRF system that has the potential to decrease the overall noise, reaching the required stability of tens of ppm on RF amplitude and phase. For the laser control side, we are replacing the long coaxial cables with fibers for both control signal transmission and laser signal reception. The control transmission side has been implemented, and the timing jitter has been reduced.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL040  
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