Patent ID: 8736198
Filing Date: 2014-05-27
Classification: H05H

Abstract:
1. A circular accelerator comprising: a bending magnet which makes charged particles circulate along a circulating orbit so as to form a charged particle beam; a radio-frequency cavity for accelerating the charged particles; a radio-frequency generator including an output connected to the radio-frequency cavity and outputting a radio-frequency into the radio-frequency cavity, via the output connected thereto, for generating an electric field for accelerating the charged particles; a radio-frequency control device which controls a radio-frequency which is generated by the radio-frequency generator; a region division device which divides betatron oscillation of charged particles which circulate along the circulating orbit into a stable region and a resonance region; an extracting device for extracting the charged particles from the circulating orbit; and a beam current detector which detects a beam current of the charged particles which are extracted from the extracting device; wherein the charged particles are extracted from the extracting device by changing the frequency of the radio-frequency generated by the radio-frequency generator so as to narrow the stable region, wherein the radio-frequency control device comprises a target current memory which stores a target current value of the beam current of charged particles which are extracted from the extracting device and a frequency determination part in which a frequency change ratio is obtained by performing a feedback control based on an error signal between a detection signal of the beam current detector and the target current value which is stored in the target current value memory and then a subsequent frequency is determined from the obtained frequency change ratio and a current frequency, and wherein a subsequent frequency, which is determined by the frequency determination part, is stored in a frequency memory part so as for the radio-frequency generator to generate the subsequent frequency which is determined.