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TY - CONF AU - Miura, A. AU - Liu, Y. AU - Miyao, T. AU - Tamura, J. ED - Schaa, Volker RW ED - Arduini, Gianluigi ED - Pranke, Juliana ED - Seidel, Mike ED - Lindroos, Mats TI - Bunch Shape Monitor Development in J-PARC Linac J2 - Proc. of IPAC2017, Copenhagen, Denmark, 14â19 May, 2017 C1 - Copenhagen, Denmark T2 - International Particle Accelerator Conference T3 - 8 LA - english AB - 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. PB - JACoW CP - Geneva, Switzerland SP - 271 EP - 273 KW - vacuum KW - electron KW - quadrupole KW - focusing KW - target DA - 2017/05 PY - 2017 SN - 978-3-95450-182-3 DO - 10.18429/JACoW-IPAC2017-MOPAB068 UR - http://jacow.org/ipac2017/papers/mopab068.pdf ER -