Advanced cathode and anode research at the Air Force Research Laboratory

High power microwave (HPM) tubes require currents and voltages generally in excess of 1 kA and 100 kV. Traditionally such systems have operated in poor vacuum (>10/sup -6/ torr) and on a single shot basis. Current work at the Air Force Research Laboratory (AFRL) has been directed toward high vacuum and high repetition rate systems, necessitating a complete revision of standard HPM "techniques". In this paper we discuss cathode and anode research in the HPM area, defining the figures of merit for AFRL cathodes and anodes. Several novel cathode and anode designs are discussed, with accompanying experimental results. Indeed, results have been so encouraging that we believe these classes of novel cathodes and anodes have application beyond HPM as replacements for thermionic cathodes.