Deflecting electromagnet and ion beam irradiating apparatus

摘要

A deflecting electromagnet has first and second magnetic poles that are opposed to each other via an inter-pole space through which an ion beam passes. The deflecting electromagnet further has: a pair of potential adjusting electrodes which are placed to sandwich a path of the ion beam in the same directions as the magnetic poles in the inter-pole space; and a DC potential adjusting power source which applies a positive voltage to the potential adjusting electrodes. The deflecting electromagnet further has a permanent-magnet group for, in the inter-pole space, forming a mirror magnetic field in which intensity is low in the vicinity of the middle in an ion beam passing direction, and intensities in locations which are respectively nearer to an inlet and an outlet are higher than the intensity in the vicinity of the middle.