Numerical investigation of the effect of cathode holder shape on hafnium cathode evaporation for an oxygen plasma cutting arc

摘要

The effects of cathode holder shape on a plasma cutting arc were investigated using a two-dimensional thermo-fluid model developed for arc plasmas with the consideration of hafnium cathode evaporation. The shape of the cathode holder was defined by a convex structure, which protruded from the surface of the cathode holder. Results showed that the vortex of gas flow near the hafnium cathode was created by the effect of the convex cathode holder. The temperature of the cathode surface decreased markedly with higher protrusion of the convex cathode holder by a rapid clockwise rotation of the gas flow. The presence of gas flow vortex towards the cathode surface reduced the mass fraction of hafnium vapour near the surface cathode. Finally, the total amount of mass loss of hafnium evaporation was predicted to decrease markedly with the effect of the convex cathode holder.