• C. Mitsuda, K. Fukami, K. Kobayashi, M. Oishi, Y. Okayasu, M. Shoji, K. Soutome, H. Yonehara
  JASRI/SPring-8, Hyogo-ken
• T. Nakanishi
  SES, Hyogo-pref.
• T. Ohshima
  RIKEN/SPring-8, Hyogo

In top-up operation at SPring-8 the horizontal beam oscillation had been excited because the injection bump orbit is not closed perfectly. For this problem, we had made an effort to reduce the residual beam oscillation by the improvement of bump magnet design, reducing the effect due to the nonlinearity of sextupole magnet and introducing pulsed corrector magnet, etc. By these improvements the average amplitude of residual oscillation has now been suppressed to the level of less than 0.1 mm. Still remaining relatively large residual oscillation comes from a non-similarity of a temporal shape of magnetic field of four bump magnets. We then started development fast kicker magnet system to give a counter kick to this part of residual beam oscillation. A key technology in this development is how to generate a large pulsed current in a short period to meet the oscillation characteristic. A newly developed fast pulsed power supply can generate a current of about 300 A, or corresponding magnetic field of 4.61 mT, with a pulse width of 1.2 us. Recently, we succeeded in the reduction of the horizontal beam oscillation at the timing of firing bump magnets by using this kicker system.