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Progress in Plasma Processing of Materials, 1997

ISBN:
1-56700-093-2 (Print)

THERMAL PROPERTIES OF A PLASMA TORCH

O.K. Chang
Inst, of Electric Power Eng., Univ. of Tech., 60965 Poznan, Poland

B. Laufer
Inst, of Electric Power Eng., Univ. of Tech., 60965 Poznan, Poland

A. Kaminska
Institute of Electric Power Engineering - Poznan University of Technology ul.Piotrowo 3A - 60-965 Poznan - Poland

Michel A. Dudeck
ICARE Inst.-CNRS and University of Paris 6, 75252 Paris, France

Abstract

The plasma jet produced by a D.C. torch using a nozzle with a cylindrical part for the arc and a divergent part for the plasma expansion is studied. A model based essentially on the energy equation is developped to describe the thermal properties of the arc in the cylindrical channel. The energy equation is solved numerically and simultaneously with a calculation of the physical properties as a function of temperature and pressure. First, for the expansion zone, the momentum and energy equations are solved by a finite difference method. This model allows to investigate the behavior of numerical solutions of plasma equations near the wall. Then, a non equilibrium model is developped for the description of expanding plasma and the pressure, velocities, heavy particle and electron temperatures and densities are determined solving momentum, compositions and energy equations.