Characteristics of W-ThO2 thermionic cathode activated with nanoscale oxide

A novel tungsten cathode consisting of tungsten matrix of equiaxed 4-mu m-f ine grains with nano-oxide (homogeneous dopants of ThO2 powder less than 20 0 nm in size) has been prepared by Hot-Pressing (HP) sintering. The microst ructure of the cathode is completely different from that of a commercial ca thode. A comparative study has been performed on the effect of the microstr ucture on the operating characteristics of the cathode. The results show th at the microstructure of the cathode has a strong effect on its characteris tics. The nano-oxide cathode demonstrated superior performances compared to the commercial electrode in are starting voltage, voltage-current characte ristics and are stability during arcing.