Magnetic field generator and charged particle beam irradiator

• US 6,246,066 B1
• Filed: 09/17/1998
• Issued: 06/12/2001
• Est. Priority Date: 12/25/1997
• Status: Expired due to Term

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Yuehu, Pu
• Primary Examiner(s): Berman, Jack
• Assistant Examiner(s): SMITH, JOHNNIE L
• Application Number:
  US09/154,752
• Time in Patent Office: 999 Days
• Field of Search: 378/136, 250/374, 250/492.3, 250/493.3, 250/493.1, 250/396.R, 250/309, 250/499, 250/292.3
• US Class Current: 250/492.3
• CPC Class Codes: G21K 5/00 Irradiation devices discharge tubes for irradiating H01J37/00
• CPC Class Codes: H05H 7/04 Magnet systems , e.g. undulators, wigglers free-electron laser H01S3/0903; Energisation thereof

Abstract

A magnetic field generator includes a movable magnetic pole pair within a stationary return yoke, modifying a magnetic field at a high speed with high precision. The magnetic field generator includes a first return yoke having a first internal volume, a magnetic pole pair with magnetic poles disposed opposite each other, disposed in the first internal volume, and movable relative to the first return yoke, and a driver for moving the magnetic pole pair within the first internal volume.

Claims

1. A magnetic field generator comprising:

a first return yoke having a first internal volume;

a magnetic pole pair comprising a pair of magnetic poles disposed opposite each other, disposed in the first internal volume, and movable relative to said first return yoke; and

a driver for moving said magnetic pole pair within the first internal volume.

2. The magnetic field generator as defined in claim 1 wherein the first internal volume is substantially circular in cross-section, said magnetic pole pair is rotatable along an internal surface of said first return yoke, and said driver rotationally drives said magnetic pole pair.

3. The magnetic field generator as defined in claim 1 comprising a second return yoke having a second internal volume, disposed in the first internal volume, and rotatable along an internal surface of said first return yoke, wherein said magnetic pole pair is fixed to said second return yoke in the second internal volume, and said driver drives said magnetic pole pair and said second return yoke.

4. The magnetic field generator as defined in claim 3 comprising a bearing of a magnetic substance disposed between said first return yoke and said second return yoke.

5. The magnetic field generator as defined in claim 1 comprising a non-magnetic magnet supporting member connecting opposed faces of each of said magnetic poles in the first internal volume.

6. The magnetic field generator as defined in claim 1 wherein a cross-section of the first internal volume has a pair of parallel sides, said magnetic pole pair is linearly movable along an internal surface of said first return yoke, and said driver linearly drives said magnetic pole pair.

7. The magnetic field generator as defined in claim 1 wherein each magnetic pole comprises a respective coil and comprising a power source for supplying a current to each coil upon stopping of movement of said magnetic pole pair and for reducing the current supplied to each coil upon movement of said magnetic pole pair.

8. The magnetic field generator as defined in claim 1 wherein said driver rotationally drives said magnetic pole pair to rotate through an angle larger than a threshold angle to a stop position of said magnetic pole pair.

9. A charged particle beam irradiator comprising:

a charged particle beam generator for generating a charged particle beam; and

a magnetic field generator for deflecting the charged particle beam to adjust a position on an irradiated object irradiated by the charged particle beam, wherein said magnetic field generator comprises;

a first return yoke having a first internal volume;

a magnetic pole pair comprising a pair of magnetic poles disposed opposite each other, disposed in the first internal volume, and movable relative to said first return yoke; and

a driver for moving said magnetic pole pair within the first internal volume.

10. The charged particle beam irradiator as defined in claim 9 wherein the first internal volume is substantially circular in cross-section, said magnetic pole pair is rotatable along an internal surface of said first return yoke, and said driver rotationally drives said magnetic pole pair.

11. The charged particle beam irradiator as defined in claim 9 comprising a second return yoke having a second internal volume, disposed in the first internal volume, and rotatable along an internal surface of said first return yoke, wherein said magnetic pole pair is fixed to said second return yoke in the second internal volume, and said driver drives said magnetic pole pair and said second return yoke.

12. The charged particle beam irradiator as defined in claim 11 comprising a bearing of a magnetic substance disposed between said first return yoke and said second return yoke.

13. The charged particle beam irradiator as defined in claim 9 comprising a non-magnetic magnet supporting member connecting opposed faces of each of said magnetic poles in the first internal volume.

14. The charged particle beam irradiator as defined in claim 9 wherein each magnetic pole comprises a respective coil and comprising a power source for supplying a current to each coil upon stopping of movement of said magnetic pole pair and for reducing the current supplied to each coil upon movement of said magnetic pole pair.

15. The charged particle beam irradiator as defined in claim 9 wherein said driver rotationally drives said magnetic pole pair to rotate through an angle larger than a threshold angle to a stop position of said magnetic pole pair.

16. A charged particle beam irradiator comprising:

a charged particle beam generator for generating a charged particle beam, and

a magnetic field generator for deflecting the charged particle beam to adjust a position on an irradiated object irradiated by the charged particle beam, wherein said magnetic field generator comprises;

a first magnetic field generator for deflecting the charged particle beam, and

a second magnetic field generator for deflecting the charged particle beam deflected by the first magnetic field generator, one of the first and second magnetic field generators comprising a first return yoke having a first internal volume and a first magnetic pole pair comprising a pair of magnetic poles disposed opposite each other, disposed in the first internal volume, and movable relative to said first return yoke.

17. The charged particle beam irradiator as defined in claim 16 wherein another of the first and second magnetic field generators comprises a second return yoke having a second internal volume and a second magnetic pole pair disposed opposite each other, disposed in the second internal volume, and movable relative to said second return yoke.

18. The charged particle beam irradiator as defined in claim 17 wherein:

the first internal volume has a substantially circular cross-section, and the first magnetic pole pair is rotatably disposed along an internal surface of said first return yoke;

said second return yoke internal volume has a substantially circular cross-section, and the second magnetic pole pair is rotatably disposed along an internal surface of said second return yoke; and

the charged particle beam irradiator comprises a driver for rotationally moving the first magnetic pole pair and the second magnetic pole pair in an interlocking manner.

19. The charged particle beam irradiator as defined in claim 16 wherein the second magnetic field generator comprising said first return yoke and said first magnetic pole pair, a cross-section of the first internal volume has a pair of parallel sides, the first magnetic pole pair is linearly movable along an internal surface of the first return yoke toward a deflection direction of said first magnetic field generator.