# US 4,395,655 A · High power gyrotron (OSC) or gyrotron type amplifier using light weight focusing for millimeter wave tubes

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- Number: US 4,395,655 A
- Document ID: US4395655A
- Status: Granted
- Kind: A
- Application number: 06/198,395
- Filed: 1980-10-20
- Granted: 1983-07-26
- Earliest claimed: 1980-10-20
- Assignees: The United States of America as represented by the Secretary of the Army
- Inventors: Gunther E. Wurthman
- Web page: https://patentgrep.com/patent/US4395655A

## CPC

- H01J 25/025: {with an electron stream following a helical path}
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)

## Abstract

An improved gyrotron oscillator or gyrotron amplifier having a plurality of trong-field magnetic arrays disposed along the length of the device. Each magnetic array comprises n electromagnets, the windings of which are arranged so that the polarity of the electromagnets alternates around each array. Further, the polarity of the corresponding magnets in successive arrays alternate axially along the device. The strong-field magnetic arrays focus and reshape the electron beam within the gyrotron, thereby increasing the efficiency of the device. Permanent magnets may be used in lieu of electromagnets but offer less control.

## Claims

### Claim 1

A microwave gyrotron tube comprising:
an evacuated elongated chamber;
a cathode located at one end of said chamber;
an injection gun located at said one end of said chamber including means for injecting a hollow, circular cylindrical electron beam into said chamber coaxial with the principal longitudinal axis thereof;
a solenoid means mounted around said tube for providing a longitudinal magnetic field in said chamber for focussing said electron beam;
said chamber including at least one r-f input cavity mounted in the path of said beam and said cavity having means for coupling r-f gyrotron energy to said beam;
the other end of said tube including a means for collecting said electron beam and a means for coupling microwave energy out of said tube;
at least one strong-field quadrupole magnetic means in said chamber adjacent to said electron beam and located between said injection gun and said cavity for reshaping said electron beam into a hollow elliptical electron beam; and
said quadrupole magnetic means including four magnets having poles extending into said chamber adjacent to said electron beam and being symetrically spaced about said beam in a plane perpendicular to said longitudinal axis with the adjacent ones of said poles having opposite polarities.

### Claim 2 (depends on 1)

The tube according to claim 1 further comprising a plurality of said cavities periodically spaced along said longitudinal axis and interleaved with a plurality of said strong-field magnetic means.