MATHEMATICAL MODELS FOR HIGH FREQUENCY PLASMA TORCHES

This paper describes a complete model for the prediction of flow, tem- perature, concentration, and electromagnetic fields for argon, argon ٫ ۵% hydrogen, argon ۱۰% hydrogen, argon ٫ ۵۰% nitrogen, and nitrogen plas- mas. These plasmas have an induction frequency of ۳ MHz and a power in the range of ۱۰-۳۰ kW. The Navier-Stokes equations, energy, mass diffusion and Maxwell's equations for electro-magnetic fields are solved based on the SIMPLER algorithm. Vector potential formalism is used for the resolution of the Maxwell's equations. The computed results show that the flow fields are sensitive to the addition of molecular gases. The coupling between plasma power and coil current has been explored and it is shown that based on the model, the minimum sustaining power for a stable plasma production can be predicted, for a given set of operating conditions.