A thermionic tungsten cathode activated with nanothoria and prepared by swaging method

Using high-energy ball milling, nanosized thoria powders were obtained. After mixing the thoria nanoparticles with tungsten powders, a nanocomposite cathode was fabricated by sintering and hot swaging. The relative density of the nanocomposite material is near 100%. The microstructure of the nanocomposite cathode is quite different from that of conventional thoriated tungsten cathodes. Most of the thoria particles in the nanocomposite are less than 100 nm in diameter, and situated on the boundaries of tungsten grains. The nanocomposite cathode shows a much lower arc initiation field than that of conventional cathode, which will improve the performance of the cathode significantly.