Accession Number : ADA113807

Title :   Rare Earth Boride Electron Emitter Materials Fabrication and Evaluation.

Descriptive Note : Final technical rept. 10 Jul 80-9 Jul 81,


Personal Author(s) : Swanson,Lynwood W ; Davis,Paul R ; Gesley,Mark A

PDF Url : ADA113807

Report Date : Mar 1982

Pagination or Media Count : 133

Abstract : Techniques were developed for routine preparation of single crystal rods of LaB6, CeB6 and PrB6 by arc float zone refining. Single crystal, oriented samples were prepared from these rods and mounted as cathodes for testing. Several mounting systems were used, and flat, pointed cone and truncated cone thermionic cathodes were studied. Pointed field emitters of LaB6(100) were also investigated. Variation of thermionic emitted current density and thermal stability of materials were studied as functions of rare earth element, bulk stoichiometry and crystal orientation. Life tests were performed on several different LaB6(100) cathodes. One such cathode operated for over 3000 hours at approximately 10 A/sq cm emitted current density with no serious physical degradation. Surface properties of the materials were investigated by various surface analysis techniques. (Author)

Descriptors :   *Single crystals, *Rare earth elements, *Borides, *Emitters, *Electrons, Bulk materials, Surface analysis, Physical properties, Degradation, Thermal stability, Thermionic emission, Cathodes, Electric arcs, Life tests, Stoichiometry

Subject Categories : Inorganic Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE