Patent attributes
An accelerator 4 includes a circular vacuum container including circular return yokes 5A, 5B. An injection electrode 18 is disposed closer to an inlet of a beam extraction path 20 in the return yoke 5B than a central axis C of the vacuum container. Magnetic poles 7A to 7F are radially disposed from the injection electrode 18 at the periphery of the injection electrode 18 in the return yoke 5B. Recessions 29A to 29F are disposed alternately with the magnetic poles 7A to 7F in the circumferential direction of the return yoke 5B. In the vacuum container, a concentric trajectory region, in which multiple beam turning trajectories centered around the injection electrode 18 are present, is formed, and an eccentric trajectory region, in which multiple beam turning trajectories eccentric from the injection electrode 18 are present, is formed around the region.
