A consideration on the transfer function between RQ field and slow extraction spill in the Main Ring of J-PARC

Increasing the duty of beam spill is one of the important issues in the slow extraction system. In the Main Ring of J-PARC, the spill feedback system combined with EQ and RQ magnet is used to smooth the spill. In this study, frequency domain characteristics between the current of RQ magnet and the beam spill was investigated. As a result, the spill intensity gain increases with the frequency, whereas phase shift decreases with the frequency. Also the transfer function was derived, which is expected to be useful to obtain the best control parameter of the spill feedback system. (author)