Low work function, long lifetime filament for electron beam-based, wire-fed metal additive manufacturing
Tantalum filaments are used in electron beam additive manufacturing to thermionically emit electrons that are used to build near-net shape, metal parts. High operating temperatures are required to emit electrons which consequently limits the lifetime of these filaments. This thesis presents the thermionic emission characteristics of drop-in filament replacements that incorporate barium calcium aluminate cermets. Barium calcium aluminate is a low work function material used with hollow cathodes in electric propulsion devices to provide very long service lifetimes by acting as a moderate temperature, ...
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