Modeling of Plasma Parameters of a Two-Jet Plasma Torch with an Intermediate Electrode

The article considers the physical processes occurring under the influence of the plasma flow of the arc of a two-jet plasma torch on the intermediate electrode—a metal workpiece with a diameter of 5 cm rotating around its axis at a velocity of 10 000 rpm. The heated surface of the metal workpiece is melted, due to centrifugal forces the material is torn off from the workpiece in the form of droplets, and after their cooling in an inert gas environment a powder of spherical metal particles is obtained (PREP process). This powder is used in additive technologies. The authors present a three-dimensional stationary model of a two-jet plasma torch with an arc closing through an intermediate electrode—a rotating metal workpiece (near-electrode processes are not taken into account). The influence of the arc current value and plasma gas flow rate on the efficiency of workpiece heating is considered. Both distributed (temperature, plasma velocity, etc.) and integral (power into the workpiece, power loss due to radiation, etc.) calculation results are presented. It is shown that the dependence of the power into the workpiece on the plasma-forming gas flow rate has a “saturation”; i.e., when a certain gas flow rate is exceeded, the power into the workpiece stops increasing. In this case, increasing the arc current is the most effective way to increase the power delivered to the workpiece.