Emission property of scandia and Re doped tungsten matrix dispenser cathode

Abstract

Scandia and rhenium doped tungsten powders have been prepared by solid–liquid doping combined with two-step reduction method. The experimental results show that scandia distributes evenly in the doped tungsten powder. Moreover, the addition of scandia and rhenium could decrease the particle size of tungsten. By using this kind of powder, scandia and rhenium doped tungsten matrix with sub-micrometer sized tungsten grains and a uniform distribution of Sc 2O 3 together with high pore density has been obtained. The emission property result shows that high space charge limited current density of more than 30 A/cm 2 at 850 °C has been obtained for this cathode. This excellent emission capability results from an active layer uniformly covering the sub-micron structure framework of the cathodes.