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Taniuchi, Y.

Paper Title Page
TUPC096 Development of Beam Loss Monitor for the SPring-8 Storage Ring 1284
 
  • Y. Shimosaki, K. Kobayashi, M. Oishi, M. Shoji, K. Soutome, Y. Taniuchi
    JASRI/SPring-8, Hyogo-ken
 
  A beam loss monitor using PIN photodiodes has been developed. To check its performance, we installed it at an in-vacuum insertion device and at the injection section in the SPring-8 storage ring. Information on the beam loss at these points will be useful for examining demagnetization of permanent magnets of insertion devices and for studying a mechanism of beam loss. A noise level at these points is however high due to stray synchrotron radiation, an induction voltage generated by pulsed injection magnets, etc. The beam loss signal is then picked up under a high noise condition. Experimental results with its countermeasure will be reported.  
THPC127 Filling of High Current Singlet and Train of Low Bunch Current in SPring-8 Storage Ring 3284
 
  • T. Nakamura, T. Fujita, K. Fukami, K. Kobayashi, C. Mitsuda, M. Oishi, S. Sasaki, M. Shoji, K. Soutome, M. Takao, Y. Taniuchi
    JASRI/SPring-8, Hyogo-ken
  • T. Ohshima
    RIKEN/SPring-8, Hyogo
  • Z. R. Zhou
    USTC/NSRL, Hefei, Anhui
 
  We performed the storage of high current singlet of 10mA/bunch and a train of bunches of 0.3mA/bunch under the bunch by bunch feedback systems with newly developed bunch current sensitive automatic attenuators with FPGA. The automatic attenuator reduces the signal level of the high current bunch by factor three to five to avoid the saturation of the feedback systems. With this system, the feedback systems suppress horizontal and vertical mode-coupling instabilities and raise the bunch current limit from 3.5mA/bunch to 12mA/bunch, and simultaneously the systems suppress the multi-bunch instabilities by resistive-wall and cavity higher order mode impedances. The improvement of the automatic attenuation system to fit to the final target of the bunch current in the train, 0.06mA/bunch, are being performed. The other problems which limit the filling patterns, such as saturation of the readout electronics of the beam position monitor system and the heating of vacuum components by high current bunches, will be briefly presented.