Preparation and characterization of scandia and Re doped tungsten matrix impregnated cathode

The paper describes the preparation and emission property of scandia and Re doped tungsten matrix impregnated cathode. By an easy and reproducible way, solid–liquid doping combined with two-step reduction, powders of tungsten particles covered with scandium oxide were obtained. Compared with scandia mixed tungsten powders prepared by mechanically mixing, scandia and rhenium doped tungsten powders had smaller particle size, for example, scandia (3 wt%) and Re (5 wt%) doped tungsten powders had the average size of about 50 nm in diameter. Based on this kind of powder, scandia and Re doped tungsten matrix with the sub-micrometer sized tungsten grains and a more uniform distribution of Sc2O3 were obtained in this paper. Scandia and Re doped tungsten matrix impregnated cathode had shown excellent emission property and good emission uniformity. The space charge limited current densities of more than 58A/cm2 at 900 °Cb could be obtained and the work function of this cathode was as low as 1.18 eV.