THERMIONIC CATHODE Russian patent published in 2000 - IPC

FIELD: electronic engineering; electronic devices using lanthanum hexaboride emitter. SUBSTANCE: in order to ensure long life of thermionic cathode by reducing internal stresses and equalizing various physical properties between substrate and intermediate barrier layers, it is provided with porous interlayer made of metal identical to that of substrate and set of intermediate barrier layers whose varying porosity gradually grows to 25-30% (15-20% for graphite substrate) and reduces to 2-3% in emissive lanthanum hexaboride layer made of powder produced by pulverizing single-crystalline part grown towards (001) edge. Proposed thermionic cathodes are noted for adequate layer-to-layer adhesion, resistance to heat impacts without cracking and crumbling and to cyclic heat treatment; they have solid emissive coating and can be used in miscellaneous electronic devices as electron sources at operating temperature of 1700-1800 C. EFFECT: improved service life and emissive properties of cathode. 2 dwg, 2 tbl