Ronnie M Watkins

US Patent:

8143788, Mar 27, 2012

Filed:

Aug 30, 2008

Appl. No.:

12/202252

Inventors:

Richard R. Hofer - Monrovia CA, US
Dan M. Goebel - Tarzana CA, US
Ronnie M. Watkins - Oro Valley AZ, US

Assignee:

California Institute of Technology - Pasadena CA

International Classification:

H01J 17/06

US Classification:

313618, 31511181

Abstract:

An apparatus and method for achieving an efficient central cathode in a Hall effect thruster is disclosed. A hollow insert disposed inside the end of a hollow conductive cathode comprises a rare-earth element and energized to emit electrons from an inner surface. The cathode employs an end opening having an area at least as large as the internal cross sectional area of the rare earth insert to enhance throughput from the cathode end. In addition, the cathode employs a high aspect ratio geometry based on the cathode length to width which mitigates heat transfer from the end. A gas flow through the cathode and insert may be impinged by the emitted electrons to yield a plasma. One or more optional auxiliary gas feeds may also be employed between the cathode and keeper wall and external to the keeper near the outlet.