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Progress in Plasma Processing of Materials, 2003

ISBN:
978-1-56700-192-1 (Print)
978-1-56700-447-2 (Online)

TRANSPORT COEFFICIENTS IN NON-EQUILIBRIUM ARGON-HYDROGEN THERMAL PLASMAS

V. Rat
PCTS -CNRS UMR 6638, University of Limoges, 123 av. A. Thomas, 87060 Limoges cedex, France

Jacque Aubreton
SPCTS University of Limoges, 123 av. A. Thomas, 87060 Limoges cedex, France

P. Andre
Laboratoire Arc Electrique et Plasmas Thermiques CNRS FRE 3120, Phys. Bât. 5 - Université Blaise Pascal, Aubière Cedex, France; and P.R.E.S. Clermont Université, Clermont-Ferrand Cedex 1, France

M. F. Elchinger
SPCTS University of Limoges, 123 av. A. Thomas, 87060 Limoges cedex, France

Pierre Fauchais
Laboratoire Sciences des Procedes Ceramiques et de Traitements de Surface UMR CNRS 6638 University of Limoges 123 avenue Albert Thomas, 87060 LIMOGES - France

A. Lefort
Laboratoire Arc Electrique et Plasmas Thermiques, Université Blaise Pascal, CNRS UMR 6069, 24 avenue des Landais, F63177 Aubiére Cedex, France

Abstract

Transport coefficients in non-equilibrium argon-hydrogen thermal plasmas, where the kinetic temperature of electrons Te is different from that of heavy species Th , are calculated at atmospheric pressure from a recent theoretical approach of Rat et al. The latter consists in deriving transport properties in thermal plasmas from the solution of the Boltzmann's equation according to the Chapman-Enskog method keeping the coupling between electrons and heavy species.
Plasma composition is obtained from a non-equilibrium constant method and a stationary kinetic calculation. First, electrical and translational thermal conductivities are compared with those evaluated with the simplified theory of transport properties of Devoto and Bonnefoi. Non-negligible discrepancies occur reaching more than 30 and 40 % respectively for the electrical and electron thermal conductivities at Te = 15000 ? for θ = 2. Second, the dependence with Te of electrical and total thermal conductivities (including translational, internal and reactional contributions) and viscosity is examined as a function of the method of calculation of plasma composition and the non-equilibrium parameter θ = Te /Th . It is emphasized that non-equilibrium transport coefficients are strongly dependent on the method of plasma composition.