Development of a 30-kW Plasma Gun System With a Long Lifetime

A hollow cathode that has extremely stable discharge characteristics has been developed. It is composed of two separated lanthanum hexaboride (LaB₆) disks in the tube as the electron emitters. The design accomplishes great advantages by extending the surface discharge area of LaB₆, an extension that is also useful for optimal fixing of LaB₆. The hollow cathode is capable of producing 30 kW (100 V and 300 A) of power continuously. The plasma beam generated by the hollow cathode passes through holes in the centers of two intermediate electrodes covered with tungsten, which is water cooled due to the high plasma temperature entailed (greater than 3000^degC ). The combination of the hollow cathode and the two intermediate electrodes is practically useful for an ion plating plasma beam source.