Beam accelerator

• US 6,713,976 B1
• Filed: 04/17/2003
• Issued: 03/30/2004
• Est. Priority Date: 10/17/2002
• Status: Expired due to Term

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Kijima, Yuko, Ishi, Yoshihiro, Zumoto, Nobuyuki, Nagayama, Takahisa
• Primary Examiner(s): VU, DAVID HUNG
• Application Number:
  US10/417,218
• Time in Patent Office: 348 Days
• Field of Search: 315/500, 315/507, 315/506, 315/501, 315/504
• US Class Current: 315/500
• CPC Class Codes: H05H 11/00 Magnetic induction accelerators, e.g. betatrons
• CPC Class Codes: H05H 7/04 Magnet systems , e.g. undulators, wigglers free-electron laser H01S3/0903; Energisation thereof

Abstract

A high performance beam accelerator in which accelerating voltage may be increased by applying a high excitation frequency to the accelerator core and controlling heat generation. The beam accelerator includes an annular hollow vessel with an annular passage, fixed magnetic field generators generating magnetic fields for deflecting and guiding a charged particle beam into an orbit, an accelerating gap for inducing an accelerating electric field, and an accelerator core for generating the accelerating electric field via the accelerating gap by changing magnetic state in accordance with electromagnetic induction. Injection to ejection of charged particles is completed within one cycle of the excitation frequency applied to the accelerator core. The accelerator core includes wound multiple layers of a ribbon-shaped soft magnetic alloy, 50 μm or less in thickness, and having a saturation magnetic flux density of 1 Tesla or more.

Claims

1. A beam accelerator comprising:

an annular hollow vessel having an annular passage inside, through which a charged particle beam passes,

a plurality of fixed magnetic field generating means for deflecting the charged particle beam and guiding the charged particle beam into an orbit in said annular passage, located along a circumferential direction of said annular hollow vessel,

an accelerating gap for inducing an accelerating electric field in the charged particle beam, located at a position of said annular hollow vessel, and

an accelerator core, surrounding said annular hollow vessel, for generating the accelerating electric field via said accelerating gap by changing magnetic state of an inner portion of said annular passage in accordance with electromagnetic induction, wherein

injection to ejection of charged particles is completed within one cycle of an excitation frequency applied to said accelerator core, and

said accelerator core includes multiple wound layers of a ribbon-shaped soft magnetic alloy, 50 μ

m or less in thickness, and having a saturation magnetic flux density of at least one Tesla.

4. The beam accelerator according to claim 1 wherein said accelerator core has an excitation frequency of at least 1 kHz.

5. The beam accelerator according to claim 1 wherein said fixed magnetic field generating means generates a fixed magnetic field which gradually becomes larger from an inside diameter-side to an outside diameter-side in said annular passage.

6. The beam accelerator according to claim 5 wherein said fixed magnetic field generating means is an electromagnet comprising a pair of pole pieces facing each other and sandwiching said annular passage and which gradually reduce a gap from an inside diameter-side to an outside diameter-side of said annular passage.

7. The beam accelerator according to claim 1 wherein said magnetic field generating means generates a magnetic field which gradually becomes larger from an inside diameter side to an outside diameter side in said annular passage.

8. The beam accelerator according to claim 7 wherein said magnetic field generating means is an electromagnet comprising a pair of pole pieces facing each other and sandwiching said annular passage and which gradually reduce a gap from an inside diameter side to an outside diameter side of said annular passage.

2. A beam accelerator comprising:

an annular hollow vessel having an annular passage inside, through which a charged particle beam passes,

a plurality of magnetic field generating means for deflecting the charged particle beam and guiding the charged particle beam into an orbit in said annular passage, located along a circumferential direction of said annular hollow vessel,

an accelerating gap for inducing an accelerating electric field in the charged particle beam, located at a position of said annular hollow vessel, and

an accelerator core, surrounding said annular hollow vessel, for generating the accelerating electric field via said accelerating gap by changing magnetic state of an inner portion of said annular passage in accordance with electromagnetic induction, wherein

injection to ejection of charged particles is completed within one cycle of an excitation frequency applied to said accelerator core,

said accelerator core comprises an inner accelerator core enclosed inside radial directions extending from an inside side-surface of said annular hollow vessel and an outer accelerator core having a c-shaped cross section and forming a ring with said inner accelerator core, and

said inner accelerator core is a soft magnetic alloy having a higher saturation magnetic flux density than said outer accelerator core.

3. The beam accelerator according to claim 2 wherein, in said outer accelerator core and said inner accelerator core, a ratio between saturation magnetic flux density of said outer accelerator core and saturation magnetic flux density of said inner accelerator core is equal to a ratio between cross sectional area of said inner accelerator core and joining area of said inner accelerator core and said outer accelerator core.