Circular accelerator

Patent metadata

Field	Value
Publication number	US-10624201-B2
Application number	US-201716341077-A
Country	US
Kind code	B2
Filing date	Feb 1, 2017
Priority date	Feb 1, 2017
Publication date	Apr 14, 2020
Grant date	Apr 14, 2020

Abstract

Conventional cyclotrons have been incapable of changing energy of a beam to be extracted. Conventional synchrotrons have been difficult to output beams in a continuous manner. An accelerator has a dense region dense region in which orbits of different energies densely gather as a result of using a radiofrequency electric field to accelerate an ion orbiting in an isochronous magnetic field in order to cause a beam orbit to be displaced in a specific direction with increasing acceleration, and a sparse region in which orbits of different energies are sparsely discrete from each other. The accelerator has a feature that a magnetic field has a magnetic field gradient in a radial direction of a beam orbit in the dense region, and a product of a gradient of magnetic field gradient and a beam size passing through the dense region becomes smaller than the magnetic field gradient.

First claim

The invention claimed is:

1. An accelerator, comprising:
a dense region in which orbits of different energies densely gather as a result of using a radiofrequency electric field to accelerate an ion orbiting in an isochronous magnetic field in order to cause a beam orbit to be displaced in a specific direction with increasing acceleration; and
a sparse region in which orbits of different energies are sparsely discrete from one another,
wherein the magnetic field has a magnetic field gradient in a radial direction of a beam orbit in the dense region, and a product of a gradient of magnetic field gradient and a beam size passing through the dense region becomes smaller than the magnetic field gradient.

2. The accelerator according to claim 1 ,
wherein the magnetic field gradient in the radial direction in the dense region is approximately linear.

3. The accelerator according to claim 1 ,
wherein a sextupole magnetic field in the dense region is zero.

4. An accelerator, comprising:
a pair of magnets that are placed facing each other to create a magnetic field between them; and
a radiofrequency cavity in which ion beams are accelerated,
wherein the magnets create a magnetic field such that a plurality of beam closed orbits of a ring shape on which the ion beams of different energies respectively orbit and the closed orbits densely gather on one side,
the magnetic field created by the magnets has a magnetic field gradient in a radial direction of the closed orbits, and
in the magnetic field created by the magnets, a product of a gradient of the magnetic field gradient and a size of the ion beam becomes smaller than the magnetic field gradient.

5. The accelerator according to claim 4 ,
wherein the magnetic field created by the magnets has the magnetic field gradient in the radial direction of a region in which the closed orbits densely gather, the magnetic field being approximately linear.

6. The accelerator according to claim 4 , further comprising:
a trim coil for a dense region that is placed in a region in which the closed orbits densely gather.

Assignees

• Hitachi Ltd

Inventors

• Aoki Takamichi
• EBINA Fuutarou
• NAKASHIMA Yuto

Classifications

• H05H13/02

  Synchrocyclotrons, i.e. frequency modulated cyclotrons · CPC title

• H05H15/00

  Methods or devices for acceleration of charged particles not otherwise provided for {, e.g. wakefield accelerators} · CPC title

• A61N2005/1087

  Ions; Protons · CPC title

• H01F7/202

  Electromagnets for high magnetic field strength (for superconducting electromagnets H01F6/00; for transformers or inductances without a magnetic core H01F30/08) · CPC title

• H05H13/005 Primary

  Cyclotrons · CPC title