Mode suppression means for gyrotron cavities

• US 4,398,121 A
• Filed: 02/05/1981
• Issued: 08/09/1983
• Est. Priority Date: 02/05/1981
• Status: Expired due to Term

• Current Assignee: Communications & Power Industries Incorporated
• Original Assignee: Varian Associates, Inc.
• Inventors: Symons, Robert S., Chodorow, Marvin
• Primary Examiner(s): Chatmon, Jr., Saxfield
• Application Number:
  US06/232,059
• Time in Patent Office: 915 Days
• Field of Search: 315/3, 315/4, 315/5, 315/5.31, 315/5.38, 315/5.35, 333/228, 333/229
• US Class Current: 315/4
• CPC Class Codes: H01J 25/025 with an electron stream following a helical path

Abstract

In a gyrotron electron tube of the gyro-klystron or gyro-monotron type, having a cavity supporting an electromagnetic mode with circular electric field, spurious resonances can occur in modes having noncircular electric field. These spurious resonances are damped and their frequencies shifted by a circular groove in the cavity parallel to the electric field.

Claims

1. In a gyrotron:

means for forming a beam of spiraling charged particles,

a hollow conducting cavity shaped to resonate in a mode with circular electric field,

an end of said cavity comprising an opening for passage of said beam,

an end of said cavity comprising an opening connecting to a circular waveguide capable of transmitting a wave having a circular electric field, the improvement being

a groove in the wall of said cavity, said groove running parallel to said electric field of said mode, the walls of said groove having low resistive loss and the interior of said groove having low dielectric loss,

whereby field patterns of modes with non-circular electric fields are perturbed with only a small dissipation of their energy.

2. The gyrotron of claim 1 wherein said cavity, said waveguide, said groove and said openings are figures of revolution about an axis.

3. The gyrotron of claim 2 wherein the outline of said beam is a figure of revolution about said axis.

4. The gyrotron of claim 1 wherein said wall of said cavity is of high-conductivity metal and the walls, including the bottom, of said groove are of high-conductivity metal and the interior of said groove is empty.