A 2-D Axisymmetric Magneto-Hydrodynamic Model of a DC Arc Plasma Torch and Its Solution Methodology

The behavior of dynamic plasma is governed by the magneto-hydrodynamic (MHD) equation, and the efficient solution is still an open challenging issue in computational electromagnetics. In this article, to efficiently predict the behavior of an engineering direct current (dc) arc plasma torch, a 2-D axisymmetric MHD model is introduced and its solution methodology is proposed. In the methodology, the initial temperature field of the MHD model is estimated based on a predicted trajectory of the plasma arc, determined by using the single-particle orbital theory; a simple yet efficient iterative procedure using a prediction-correction approach to determine the magnetic field and to solve the corresponding 2-D finite-element equations of the mass, momentum, and energy conservations is proposed; and an approach to solve the extremely small conductivity near the electrodes is introduced. Finally, a finite element method code is developed and used to compute the multi-physics fields of the plasmas with promising results.