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

Abstract

The effects of the 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 the hafnium cathode evaporation. The shape of the cathode holder shape was defined a convex structure which protrudes 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 the higher protrusion of the convex cathode holder by a rapid clockwise rotation of gas flow. The presence of gas flow vortex toward to the cathode surface reduces the mass fraction of hafnium vapor near the surface cathode. Finally, the total amount of mass loss of the hafnium evaporation was predicted to decrease markedly with the effect of the convex cathode holder.

Modeling of a xenon short arc lamp considering the behavior of tungsten vapour evaporated from electrodes

“…where Y is the total mass fraction of the tungsten vapour species. The diffusion coefficient of the tungsten vapour in the xenon D W-Xe [m 2 /s] is expressed as follow [44];…”

“…The mass production of the tungsten vapour from the electrode is calculated as a function of the melting rate (ratio of liquid to solid) f m . The equation for the melting rate f m is given as follow [44];…”

Modeling of Thermal Plasma Processes: The Importance of Two‐Way Plasma‐Surface Interactions

“…The influence of the shape of the copper cathode holder on vaporization of the hafnium cathode has also been investigated computationally . If the hafnium is recessed inside the holder, not only is the gas flow velocity away from the cathode reduced, but a vortex is generated leading to gas flow toward the cathode.…”

Observation system of molten steel behavior on plasma arc cutting surface

“…Some of the technical issues involved in plasma cutting include those related to the torch body such as the erosion phenomenon of the hafnium cathode and those related to cutting quality such as dross adhesion to the object and the perpendicularity of the cutting surface. In this study, we have focused on the problem of dross adhesion to the object, which is one of the major factors that affect cutting quality.…”