Directly heated cathode structure

Abstract

A directly heated cathode structure includes a porous pellet impregnated with a cathode material, a first metal member fixed to a surface of the porous pellet, a second metal member welded to the first metal member, and a filament interposed between the first and second metal members. A method for manufacturing a directly heated cathode structure includes manufacturing a porous pellet having a multiplicity of cavities, welding a first metal member to a surface of the porous pellet with a brazing layer, impregnating the cavities of the pellet with an electron radiating material, and welding a second metal member to the first metal member with a filament disposed between the first and second metal members. The useful life of the cathode structure is prolonged since thermions are not emitted through the surface of the pellet covered by the metal member.

Dependencies are inferred from the claim text.