From the derivation of two-temperature diffusion number fluxes of species proposed by Rat et al and that of ambipolar diffusion coefficients, combined diffusion coefficients introduced by Murphy at equilibrium are extended to non-equilibrium thermal plasmas, where the kinetic temperature of electrons Te is different from that of heavy species Th .
Two-temperature ordinary and thermal combined diffusion coefficients are calculated in an argon-helium plasma at atmospheric pressure up to 30,000 K. Plasma composition is obtained using a non-equilibrium constant method. The dependence on the electron temperature of combined diffusion coefficients is analyzed for different mole percentages of argon in the mixture and for different values of the non-equilibrium parameter
θ = Te /Th.
Similar behaviors to those obtained at equilibrium are highlighted with a decrease in the combined diffusion coefficients, at fixed electron temperature, as θ increases.