| 摘要 |
An accelerator is provided which can efficiently emit ion beams of different energies. This accelerator 4 comprises a circular vacuum container which contains a circular return yoke 5A, 5B. With respect to the central axis C of the vacuum container, an incidence electrode 18 is arranged towards the entrance of a beam emission path 20 inside of the return yoke 5B. Inside of the return yoke 5B, electrodes 7A-7F are arranged radially from the incidence electrode 18 in the periphery of the incidence electrode 18. Recesses 29A-29F are arranged alternately with the electrodes 7A-7F in the circumferential direction of the return yoke 5B. In the vacuum container, an orbit-concentric region is formed in which multiple beam orbits centered on the incidence electrode 18 are present, and, in the periphery of said region, an orbit-eccentric area is formed in which multiple beam orbits eccentric to the incidence electrode 18 are present. In the orbit-eccentric region, the beam orbits between the incidence electrode 18 and the entrance to the beam emission path 20 are denser, and the interval between beam orbits becomes wider on the side opposite by 180° to the entrance to the beam emission path 20 with the incidence electrode 18 as a reference point. |
