The CPC: A00000000 medium current density, high reliability cathode

The coated powder cathode is an inexpensive, reproducible emitter which combines the virtues of various conventional cathode types, and is suited to use in modern high-power, high-reliability electron tubes. It is best considered as a modification of the classic oxide cathode in which each particle of the emissive coating is covered with a thin layer of nickel. Inherent advantages of this cathode over the oxide cathode include the ability to sustain current densities up to 1 amp/cm2 over long, calculable lifetimes, increased flexibility in time and temperature during processing, and improved coating adhesion. This paper describes the concept, fabrication and mechanism of the cathode and presents data obtained from a diode evaluation program.