Steady‐state discharge test of coaxial LaB6 cathode

Results of steady‐state discharge test of coaxial LaB6 cathodes in a multicusp plasma generator are described. After a single‐unit test of a compact, 6.4‐mm‐diam coaxial LaB6 cathode, a discharge test of two cathodes with one heater power supply was carried out with success. In addition, a new tapered coaxial cathode, which was designed to prevent overheating of LaB6 due to ohmic heating by discharge current, was investigated. During steady‐state plasma source operation, a discharge current as high as 180 A was obtained with this tapered cathode.