Author: Liu, Y.
Paper Title Page
MOPAB068 Bunch Shape Monitor Development in J-PARC Linac 271
 
  • A. Miura, J. Tamura
    JAEA/J-PARC, Tokai-mura, Japan
  • Y. Liu
    KEK/JAEA, Ibaraki-Ken, Japan
  • T. Miyao
    KEK, Ibaraki, Japan
 
  At Japan accelerator reserch complex (J-PARC), the linac, which serves as the injector for the downstream 3-GeV synchrotron, accelerates a negative-hydrogen-ion beam (H) to obtain a 400-MeV beam energy. We use an accelerating frequency of 324 MHz for the accelerator cavities and of 972 MHz. Both the centroid-phase set point at the frequency jump from 324 MHz to 972 MHz and the phase-width control are key issues for suppressing the excess beam loss. In order to optimize a set point of the tuning cavities, we developed a bunch-shape monitor (BSM) to measure the phase width as well as a tuning strategy to minimize the beam loss. In the development of the BSM, the design developed in the INR, Russia. Because the BSM had first experienced to be used between accelearation cavities, we need to protect the leak-magnetic field from quadrupole magnets and outgas impacts to cavities. We installed a BSM again in the beamline, BSM started to measure the phase width and evaluated its performances with a peak-beam-current dependence. We proposed new strategy to use BSM-measurment data for the tuning cavity. This paper describes the BSM development, its modification, and new strategy.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB068  
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MOPIK118 Model Based Optics Studies in the MEBT Section of SNS 814
 
  • A.P. Shishlo, A.V. Aleksandrov, A.P. Zhukov
    ORNL, Oak Ridge, Tennessee, USA
  • Y. Liu
    KEK/JAEA, Ibaraki-Ken, Japan
 
  Funding: This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC0500OR22725 with the U.S. Department of Energy.
The paper presents the beam dynamics studies for the Medium Energy Beam Transport (MEBT) section of the Spallation Neutron Source (SNS) accelerator. The analysis of measurements is based on the PyORBIT linac model. The diagnostics data includes wire scanners' profiles, slit-harp and slit-slit transverse emittances, MEBT re-bunchers calibration data, and bunch length measurements. The MEBT is a matching section between RFQ and a Drift Tube Linac (DTL). It is also a place for beam halo scraping which helps to reduce beam loss in downstream linac sections. The linac simulation code was benchmarked against the diagnostics data.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK118  
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