CESIUM VAPOR CATHODE STUDY
Abstract
Two approaches to the problem of extracting high density electron beams from synthesized plasmas are under study: One uses a common surface for both ion and electron emission, the other employs separate surfaces. The first tantalum common emitter hollow cathode tube, designated CE-1, was completed and awaits testing. The cathode, designed to yield an extracted current density of 100 amp/sq cm was taken up to its full operating temperature of 2250 K twice during tube processing with no mechanical or thermal difficulties being encountered. Experiments were carried out on plasma-cathode tubes with separate ion and electron emitters. These can be operated at temperatures lower than those of common-emit ter surfaces since each emitter can be optimized separately. An extracted current density of 32 amp/sq cm was obtained from the aperture in a niobium electrode (this electrode was used for contact ionization of cesium and was located op posite an L-cathode). The synthesized plasma in this tube became the common-emitter type since L-cathode evaporants, which continually deposited on the niobium surface, caused the surface to be also a good electron emitter. In another tube, a hafnium surface was used for cesium contact ionization and a duo-emitter-type plasma was successfully synthesized. The extracted current density through the aperture was 12.3 amp/ sq cm. This density should be considerably increased if excess ions are provided in the exit aperture area and if greater precaution is taken to avoid contamination of the L-cathode.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1963
- Accession Number
- AD0403833
Entities
People
- A. L. Eichenbaum
- F. Norman
- H. Sobol
- P. T. Smith
Organizations
- Sarnoff Corporation