La–Mo emitters in hollow cathodes

Abstract

A hollow cathode which utilizes lanthanum molybdenum (LM) as the active electron emitter is described and compared in performance to a LaB₆ emitter of equal area in an identical configuration. Tests in both argon and hydrogen produced effective emission current densities of up to 10 A/cm² from the LM material in continuous and long pulse operation. Examination after 40 h running time showed no sign of damage or rapid evaporation. Impurity build up on the emitting surfaces which stopped the LaB₆ emission after 50 h was not apparent with the LM and long lifetimes are anticipated for cathodes using this emitter.