Coupled-cavity drift-tube linac

• US 5,578,909 A
• Filed: 07/15/1994
• Issued: 11/26/1996
• Est. Priority Date: 07/15/1994
• Status: Expired due to Fees

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Billen, James H.
• Primary Examiner(s): Patel, Nimeshkumar D.
• Application Number:
  US08/275,865
• Time in Patent Office: 865 Days
• Field of Search: 315/500, 315/505, 315/5.41, 315/5.42, 315/5.46, 315/5.47
• US Class Current: 315/505
• CPC Class Codes: H05H 7/18 Cavities; Resonators travelling-wave tubes H01J23/18; hyperfrequency cavities in general H01P7/04, H01P7/06
• CPC Class Codes: H05H 7/22 Details of linear accelerators, e.g. drift tubes H05H7/02 - H05H7/20 take precedence
• CPC Class Codes: H05H 9/00 Linear accelerators

Abstract

A coupled-cavity drift-tube linac (CCDTL) combines features of the Alvarez drift-tube linac (DTL) and the π-mode coupled-cavity linac (CCL). In one embodiment, each accelerating cavity is a two-cell, 0-mode DTL. The center-to-center distance between accelerating gaps is βλ, where λ is the free-space wavelength of the resonant mode. Adjacent accelerating cavities have oppositely directed electric fields, alternating in phase by 180 degrees. The chain of cavities operates in a π/2 structure mode so the coupling cavities are nominally unexcited. The CCDTL configuration provides an rf structure with high shunt impedance for intermediate velocity charged particles, i.e., particles with energies in the 20-200 MeV range.

Claims

1. A linear accelerator (linac) for accelerating charged particles with radio frequency (rf) energy through an intermediate velocity range, said accelerator comprising:

a plurality of accelerating cavities, each one of said accelerating cavities defining input and output coaxial bore tubes connecting adjacent ones of said accelerating cavities; and

a number of drift tubes, n, within each of said accelerating cavities located intermediate and coaxial with said input and output bore tubes, said n drift tubes defining n+1 accelerating gaps between said input and output bore tubes, wherein the center-to-center spacing between successive ones of said accelerating gaps in said accelerating cavity is the distance a particle travels in one period of said rf.

2. A linac according to claim 1, wherein each said accelerating cavity has a length of (2n+1)/2 times the distance a particle travels in one period of said rf.

3. A linac according to claim 1 or claim 2, wherein successive ones of said accelerating gaps in adjacent ones of said accelerating cavities have a center-to-center spacing defined by one-half the distance a particle travels in one period of said rf.

4. A linear accelerator (linac) for accelerating charged particles through an intermediate velocity range, said accelerator comprising:

a plurality of resonantly coupled accelerating cavities coupled with nominally unexcited coupling cavities to form a π

/2 mode linac accelerating structure, each one of said accelerating cavities defining input and output coaxial bore tubes connecting adjacent ones of said accelerating cavities; and

a number of drift tubes n within each of said accelerating cavities located intermediate and coaxial with said input and output bore tubes, said n drift tubes defining n+1 accelerating gaps between said input and output bore tubes.

5. A linac according to claim 4, wherein each said accelerating cavity has a length of (2n+1)/2 times the distance a particle travels in one period of said rf.

6. A linac according to claim 4, wherein have a center-to-center spacing defined by successive ones of said accelerating gaps in said accelerating cavity the distance a particle travels in one period of said rf.

7. A linac according to claim 6, wherein each said accelerating cavity has a length of (2n+1)/2 times the distance a particle travels in one period of said rf.

8. A linac according to any one of claims 4 through 7 wherein successive ones of said accelerating gaps in adjacent ones of said accelerating cavities is have a center-to-center spacing defined by one-half the distance a particle travels in one period of said rf.

9. A linear accelerator (linac) for accelerating charged particles through an intermediate velocity range, said accelerator comprising:

a plurality of accelerating cavities, each one of said accelerating cavities defining input and output coaxial bore tubes connecting adjacent ones of said accelerating cavities; and

a number of drift tubes n within each of said accelerating cavities located intermediate and coaxial with said input and output bore tubes, said n drift tubes defining n+1 accelerating gaps between said input and output bore tubes;

wherein each said accelerating cavity has a length of (2n+1)/2 times the distance a particle travels in one period of said rf.

10. A linac according to claim 9, wherein successive ones of said accelerating gaps in said accelerating cavity have a center-to-center spacing defined by the distance a particle travels in one period of said rf.

11. A linac according to claim 9 or claim 10, wherein successive ones of said accelerating gaps in adjacent ones of said accelerating cavities is have a center-to-center spacing defined by one-half times the distance a particle travels in one period of said rf.