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
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