PROBLEM TO BE SOLVED: To provide a charged particle beam irradiation system capable of suppressing generation of overshoot in emission beam current in starting beam emission, while improving beam stop speed.SOLUTION: High-frequency voltage is applied to a high-frequency electrode for emission provided on a synchrotron in performing emission control for a charged particle beam from the synchrotron, where the high-frequency voltage is composed of first high-frequency voltage for increasing oscillation amplitude so as to exceed a stability limit to make a beam orbiting in the synchrotron be emitted outside the synchrotron and second high-frequency voltage for making a charged particle beam orbiting in the vicinity of the stability limit be preferentially emitted. An amplitude value of the second high-frequency voltage is set to be 0 before starting beam emission, is gradually increased after starting the beam emission, and is kept at a predetermined amplitude value after the amplitude value has reached the predetermined amplitude value.COPYRIGHT: (C)2015,JPO&INPIT【課題】ビーム停止速度を向上しつつ、ビーム出射開始時の出射ビーム電流にオーバーシュートが生じるのを抑制できる荷電粒子ビーム照射システムを提供する。【解決手段】シンクロトロンから荷電粒子ビームの出射制御を実施する際、シンクロトロンに設けられた出射用高周波電極に印加する高周波電圧として、シンクロトロン内を周回するビームをシンクロトロン外に出射させるため、安定限界を超えるように振動振幅を増大させるための第一高周波電圧と、安定限界の近傍を周回する荷電粒子ビームを優先的に出射させるための第二高周波電圧とで構成される高周波電圧を印加し、第二高周波電圧の振幅値は、ビーム出射開始前には振幅値を0としておき、ビーム出射開始とともに漸増的に振幅値を増大し、所定の振幅値に到達したらその値を維持する。【選択図】図5
