Time-Dependent 2D Modeling of Magnetron Plasma Torch in Turbulent Flow

A theoretical model is presented to describe the electromagnetic,heat transfer andfluid flow phenomena within a magnetron plasma torch and in the resultant plume,by using acommercial computational fluid dynamics (CFD) code FLUENT.Specific calculations are pre-sented for a pure argon system (i.e.,an argon plasma discharging into an argon environment),operated in a turbulent mode.An important finding of this work is that the external axial mag-netic field (AMF) may have a significant effect on the behavior of arc plasma and thus affectsthe resulting plume.The AMF impels the plasma to retract axially and expand radially.As aresult,the plasma intensity distribution on the cross section of torch seems to be more uniform.Numerical results also show that with AMF,the highest plasma temperature decreases and theanode arc root moves upstream significantly,while the current density distribution at the anodeis more concentrated with a higher peak value.In addition,the use of AMF then induces a strongbackflow at the torch spout and its magnitude increases with the AMF strength but decreaseswith the inlet gas velocity.