Preparation of porous tungsten materials for dispenser cathodes–A brief review

Abstract

The thermal cathode, as the electron emission source of the most widely used vacuum electronic devices, is considered to be the “heart” of the vacuum electronic devices, and has evolved from the initial pure metal cathode to the diffusion cathode composed of porous tungsten matrix material and active emission material. It has been shown that the pore properties of porous tungsten matrix materials and the selection of active materials affect the performance of dispenser cathodes by determining the magnitude and distribution of the work function. Herein, this review analyzes the progress and key points in the preparation of porous tungsten materials in terms of pore properties, aiming at avoiding the degradation of cathode performance due to the poor properties of porous tungsten matrix materials. An outlook on cathode preparation and performance improvement is also presented in the article, especially a positive outlook on the application of binder jetting technology for rapid preparation of porous tungsten matrix materials.