TUOM02 　ビームダイナミクス・加速器理論　 8月9日 会議室201 9:20 - 9:40

J-PARC 3GeVシンクロトロンにおけるビーム不安定性の抑制

Beam Instability Suppression in the 3-GeV RCS of J-PARC

○サハ プラナブ　クマル，発知 英明，菖蒲田 義博，原田 寛之（J-PARC/原子力機構）

○Pranab Kumar Saha, Hideaki Hotchi, Yoshihiro Shobuda, Hiroyuki Harada (J-PARC/JAEA)

The beam instability in the 3-GeV RCS (Rapid Cycling Synchrotron) is caused by the transverse impedance of the extraction kicker magnets. At 80% of the designed 1 MW beam power, significant beam instability occurs depending on the choice of betatron tunes even if the degree of chromaticity correction is reduced to be a minimum. The parameter space at high intensity thus becomes narrower, while RCS has to satisfy multi-users demand in the downstream facilities. In the simulation by using ORBIT code we studied in detail the beam instability nature and parameter dependence in order to take measures to suppress the beam instability at 1 MW and also for choices on the betatron tunes needed for further beam loss mitigation as well as to improve extracted beam qualities. The simulation results are well reproduced in the measurements. An acceleration of 1 MW beam has already been successfully accomplished, while further efforts are ongoing in order to realize enough parameter variation for further beam loss reduction as well as to ensure the beam qualities requested by the downstream facilities. A detail of simulation and experimental results are presented in this paper.