Calculating transport coefficients in two-component plasmas with mean force kinetic theory

The electrical conductivity, thermoelectric and electrothermal conductivity, thermal conductivity, and shear viscosity of a classical ion-positron plasma are computed using mean force kinetic theory (MFKT) [1]. Through comparisons with molecular dynamics (MD) simulations, it is shown that MFKT accurately predicts the value of all transport coefficients up to a species coupling strength of Γ ~ 20. This is a significant improvement over the traditional Chapman-Enskog result, which breaks down at Γ ~ 0.1. This work also clarifies the differences in how transport coefficients are defined in MD versus kinetic theory. While unambiguous in one-component systems, the presence of diffusion in mixtures leads to conflicting definitions. In particular, we show that the diffusive force defined in the Chapman-Enskog procedure must be altered to enable accurate comparisons.

[1] Scott D. Baalrud, Jérôme Daligault; Mean force kinetic theory: A convergent kinetic theory for weakly and strongly coupled plasmas. Phys. Plasmas 1 August 2019; 26 (8): 082106.