Accelerator and particle beam irradiation system

Patent metadata

Field	Value
Publication number	US-10117320-B2
Application number	US-201415513584-A
Country	US
Kind code	B2
Filing date	Dec 8, 2014
Priority date	Dec 8, 2014
Publication date	Oct 30, 2018
Grant date	Oct 30, 2018

Abstract

The accelerator includes a circular vacuum container which contains a circular return yoke. With respect to the central axis of the vacuum container, an incidence electrode is arranged towards the entrance of a beam emission path inside of the return yoke. Inside of the return yoke, electrodes are arranged radially from the incidence electrode in the periphery of the incidence electrode. Recesses are arranged alternately with the electrodes in the circumferential direction of the return yoke. In the vacuum container, an orbit-concentric region is formed in which multiple beam orbits centered on the incidence electrode 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 are present. In the orbit-eccentric region, the beam orbits between the incidence electrode and the entrance to the beam emission path are denser.

First claim

The invention claimed is:

1. An accelerator comprising:
an annular main coil;
a plurality of magnetic poles configured to form isochronous magnetic fields;
an ion injection port configured to inject ions into an ion injection portion disposed at a position that is different from a position of a center of gravity of the main coil in a radial direction;
an acceleration electrode configured to accelerate the ions; and
an extraction port through which an accelerated ion beam is extracted,
wherein the ion injection portion, a tip of an inner circumferential end portion of the acceleration electrode, or a tip of one of the magnetic poles extends closer to the extraction port than the center of gravity of the main coil in the radial direction.

2. The accelerator according to claim 1 , further comprising:
a pair of iron cores that are joined together in a state where a beam turning region, on which a plurality of beam turning trajectories are formed, is interposed therebetween,
wherein the extraction port passes through the iron cores,
wherein the center of gravity of the main coil is positioned on a central axis of the main coil,
wherein the ion injection portion is disposed at the position that is closer to an inlet of the extraction port than the central axis of the main coil,
wherein each of the iron cores extends radially from the ion injection portion at the periphery of the ion injection portion, forms the magnetic poles, a tip end of each of which faces the ion injection portion, and forms a plurality of recessions which extend radially from the ion injection portion at the periphery of the ion injection portion,
wherein the magnetic poles and the recessions are alternately disposed at the periphery of the ion injection portion, and
wherein the main coil surrounds the multiple magnetic poles and the multiple recessions which are disposed inside each of the iron cores.

3. The accelerator according to claim 2 ,
wherein a first recession, which is one of the recessions positioned between two of the magnetic poles adjacent to each other in a circumferential direction of the main coil, and a second recession, which is another of the recessions positioned between another pair of two of the magnetic poles adjacent to each other in the circumferential direction, are disposed along a straight line that connects the inlet of the extraction port positioned inside the main coil to the central axis of the main coil, and
wherein the inlet of the extraction port opens in the second recession, and the first recession is disposed 180° opposite to the second recession relative to the central axis of the main coil.

4. The accelerator according to claim 3 ,
wherein each of the magnetic poles has bent points, and a portion of each of the magnetic poles between the bent points and an end surface thereof facing the main coil is bent toward the first recession.

5. The accelerator according to claim 4 ,
wherein in each of the iron cores, the magnetic poles, which are disposed on a plane perpendicular to the central axis and in regions on both sides of the straight line, are disposed in symmetry relative to the straight line.

6. The accelerator according to claim 3 , further comprising:
a beam current measuring apparatus that is disposed in the first recession and on a trajectory plane which is present in the beam turning region, on which the beam turning trajectories are formed, and which is perpendicular to the central axis.

7. A particle beam irradiation system comprising:
the accelerator according to claim 1 ; and
an irradiation apparatus configured to output the ion beam extracted from the accelerator.

8. An accelerator comprising:
a pair of iron cores which are installed to face each other;
a plurality of magnetic poles configured to form isochronous magnetic fields between the iron cores;
an ion injection port configured to inject ions into an ion injection portion disposed at a position that is different from a position of a center of the iron cores in a radial direction;
an acceleration electrode configured to accelerate the injected ions; and
an extraction port through which an accelerated ion beam is extracted,
wherein the ion injection portion, a tip of an inner circumferential end portion of the acceleration electrode, or a tip of one of the magnetic poles extends closer to the extraction port than the center of the iron cores in the radial direction.

9. The accelerator according to claim 8 ,
wherein the extraction port passes through the iron cores,
wherein the pair of iron cores are joined together in a state where a beam turning region, on which a plurality of beam turning trajectories are formed, is interposed therebetween,
wherein the ion injection portion is disposed at the position that is closer to an inlet of the extraction path than the center of the iron core
wherein each of the iron cores extends radially from the ion injection portion at the periphery of the ion injection portion, forms the magnetic poles, a tip end of each of which faces the ion injection portion, and forms a plurality of recessions which extend radially from the ion injection portion at the periphery of the ion injection portion,
wherein the magnetic poles and the recessions are alternately disposed at the periphery of the ion injection portion, and
wherein the main coil surrounds the magnetic poles and the recessions which are disposed inside each of the iron cores.

10. The accelerator according to claim 9 ,
wherein a first recession, which is one of the recessions positioned between two of the magnetic poles adjacent to each other in a circumferential direction of the main coil, and a second recession, which is another of the recessions positioned between another pair of two of the magnetic poles adjacent to each other in the circumferential direction, are disposed along a straight line that connects the inlet of the extraction port positioned inside the main coil to the central axis of the main coil, and
wherein the inlet of the extraction port opens in the second recession, and the first recession is disposed 180° opposite to the second recession relative to the central axis of the main coil.

11. An accelerator comprising:
an annular main coil;
a plurality of magnetic poles configured to form isochronous magnetic fields;
a plurality of acceleration electrodes configured to accelerate ions,
wherein the acceleration electrodes are installed to extend from a position of an inner surface of the main coil toward an inside of the main coil, and
wherein a respective tip end portion of each of the acceleration electrodes, which extends away from the inner surface of the main coil and is positioned inside the main coil, is disposed at a position that is different from a position of a center of gravity of the main coil in a radial direction.

12. The accelerator according to claim 11 , further comprising:
a pair of iron cores that are joined together in a state where a beam turning region, on which a plurality of beam turning trajectories are formed, is interposed therebetween,
an ion injection port configured to inject the ions into an ion injection portion disposed at a position that is different from a position of a center of the iron cores in the radial direction; and
an extraction port which passes through the iron cores and through which an accelerated ion beam is extracted,
wherein the ion injection portion is formed in the beam turning region, and is disposed closer to an inlet of the extraction port than the center of gravity of the main coil,
wherein the center of gravity of the main coil is positioned on a central axis of the main coil,
wh

Assignees

• Hitachi Ltd

Inventors

• Aoki Takamichi
• Ebina Futaro
• Nishiuchi Hideaki
• Hara Shigemitsu
• Umezawa Masumi
• Seki Takayoshi

Classifications

• A61N2005/1087

  Ions; Protons · CPC title

• H05H2277/11

  Radiotherapy · CPC title

• H05H13/04

  Synchrotrons · CPC title

• H05H13/005 Primary

  Cyclotrons · CPC title

• H05H7/08

  Arrangements for injecting particles into orbits · CPC title