Overview and performance of a waveguide ECR plasma cathode with permanent magnets

A waveguide electron cyclotron resonance (ECR)-heated plasma cathode has been developed as a long-lived alternative to the thermionic emitter-based hollow cathode assembly (HCA) for space applications, primarily as a neutralizer source for electric propulsion systems used on long-term missions. The use of a microwave discharge as an electron source could avoid lifetime limitations of the well-established HCA, which arise from erosion of the emissive insert and evaporation of impregnate material in the insert. The device to be presented utilizes traveling microwaves, as opposed to direct heating from a wire antenna, to generate the source discharge. As a result, this plasma source also avoids lifetime constraints associated with other microwave plasma cathodes due to antenna erosion.