This paper presents the first application to an argon atmospheric plasma of
a very recent derivation of a two-temperature (2T) transport properties
theory, based on the Chapman-Enskog method expanded up to the fourth
approximation, where only elastic processes are considered. The kinetic
electron temperature Te is assumed to be different from that of heavy
species Th, chemical equilibrium being achieved. This new theory,
where electrons and heavy species are coupled, allows one to determine 2T
diffusion coefficients which was not the case of the previous ones.
First, basic definitions of transport fluxes are recalled and a binary
diffusion coefficient approximation is defined which involves an asymmetric
relationship between these coefficients.
Second, a particular care is taken in choosing the most recent data of
potential interactions or elastic differential cross sections in order to
determine the collision integrals.
Third, a convergence study of transport coefficients is led to evaluate
the influence of the non-equilibrium parameter θ = Te/Th on this convergence. It is shown that
changing θ does not modify the convergence of transport
coefficients. Moreover, ordinary and thermal diffusion coefficients,
electrical and electron translational thermal conductivities as well as
viscosity are displayed as functions of the electron temperature for
different values of θ = Te/Th. It is pointed out
that the non-equilibrium parameter θ has a non-negligible influence
on transport coefficients. Besides, recently, it has been shown that the 2T
simplified theory of transport properties, very often used in modelling,
does not allow one to achieve mass conservation. Consequently, a comparison
is presented between the 2T simplified theory and this new approach.
Significant differences are found in the electrical conductivity and the
electron translational thermal conductivity.