Thermionic emission properties of a lanthanum hexaboride/rhenium cathode

Abstract

This paper describes an experimental investigation of the thermionic emission properties of a rhenium tape coated with lanthanum hexaboride, and considers its usefulness as a low temperature emitter for demountable vacuum ionization gauges and mass spectrometers. Methods of preparation and processing are described and measurements of the Richardson emission constants are given. The poisoning of the emission by those gases generally found in vacuum systems has been studied and the extent to which the activity can subsequently be restored is described. Measurements have also been made of the rate of evaporation of active material from the cathode surface.