Physical Processes in the <i>L</i> Cathode

Abstract

The activity of this barium-on-tungsten cathode is maintained by dispensing barium from a pellet of barium compound. The dispensing mechanism is shown to be controlled by surface diffusion of barium over tungsten. Despite incomplete coverage of the emitting surface with barium, and almost complete absence of streaming of active material out through pores in the surface material, evaporation of barium is sufficient to be of concern in certain applications.