Simulation, measurement, and mitigation of beam instability caused by the kicker impedance in the 3-GeV rapid cycling synchrotron at the Japan Proton Accelerator Research Complex

Saha, P. K.   ; Shobuda, Yoshihiro   ; Hotchi, Hideaki  ; Harada, Hiroyuki  ; Hayashi, Naoki  ; Kinsho, Michikazu  ; Tamura, Fumihiko   ; Tani, Norio  ; Yamamoto, Masanobu   ; Watanabe, Yasuhiro  ; Chin, Y. H.*; Holmes, J. A.*

The transverse impedance of the extraction kicker magnets in the 3-GeV RCS of J-PARC is a strong beam instability source and it is one of the significant issue to realize 1 MW beam power as practical measures are yet to be implemented to reduce the impedance. In the present research realistic simulation by updating the simulation code to cope with all time dependent machine parameters were performed in order to study the detail of beam instability nature and to determine realistic parameters for beam instability mitigation. The simulation results were well reproduced by the measurements, and as a consequence an acceleration to 1 MW beam power has also been successfully demonstrated. To further increase of the RCS beam power up to 1.5 MW, beam instability issues and corresponding measures have also been studied.