Accelerator and particle therapy system
AssigneeHitachi High-Tech Corporation
InventorsTakamichi Aoki, Takayoshi Seki, Yuto Nakashima
Life of this patent
Estimating the term…
Abstract
As the ion beam is accelerated, the radii of the closed orbits gradually increase, and the centers thereof move in a direction approaching the peripheral edge portion along a predetermined radial direction of the cavity, and upon reversing the direction of movement, move further toward the center of the cavity. The intensity distribution in the orbital plane of the main magnetic field is designed to realize the foregoing feature. Thus, an accelerator is provided that is compact and that enables the energy of an extracted beam to be changed, that enhances the efficiency of beam injection into the accelerator from an external ion source, and that improves a dose rate of the resulting extracted ion beam.
Claims13
An accelerator comprising:
- an electromagnet that includes a pair of magnetic poles arranged opposite each other having an orbital plane for circulating an ion beam interposed therebetween and that forms a main magnetic field that generates a plurality of closed orbits on the orbital plane;
- an ion injection through-hole formed in the magnetic pole in order to externally introduce an ion beam to a predetermined injection position on the orbital plane;
- a radiofrequency acceleration cavity that is inserted into a cavity formed between the pair of magnetic poles and that generates a radio frequency for accelerating the ion beam circulating in the orbital plane;
- an additional magnetic field generator that is disposed on an outer periphery of the cavity, that feeds a magnetic field to the moving ion beam on one or more closed orbits of an outermost periphery and inside the outermost periphery such that the direction of movement of the ion beam is made to deviate from the closed orbits;
- and
- an extraction channel that guides the ion beam which has deviated from the closed orbits, to an outside of the cavity,
- wherein an intensity distribution in the orbital plane of the main magnetic field is designed such that, as the ion beam is accelerated, the radii of the closed orbits gradually increase, and the centers thereof move in a direction approaching the peripheral edge portion along a predetermined radial direction of the cavity, and upon reversing the direction of movement, move further toward the center of the cavity.
Dependencies are inferred from the claim text.