Characteristics of W-ThO/sub 2/ thermionic cathode activated with nanoscale oxide

A novel tungsten cathode consisting of tungsten matrix of equiaxed 4-/spl mu/m-fine grains with nanooxide (homogeneous dopants of ThO/sub 2/ powder less than 200 nm in size) has been prepared by hot-pressing (HP) sintering. The microstructure of the cathode is completely different from that of a commercial cathode. A comparative study has been performed on the effect of the microstructure on the operating characteristics of the cathode. The results show that the microstructure of the cathode has a strong effect on its characteristics. The nanooxide cathode demonstrated superior performances compared to the commercial electrode in arc starting voltage, voltage-current characteristics and arc stability during arcing.