Analytic models for interdiffusion in dense plasma mixtures

Abstract

The characteristics of atomic-scale mixing are determined by diffusive processes driven by gradients. One such process is interdiffusion, a process driven by density gradients. We consider the various options for formulating interdiffusion in terms of Green-Kubo autocorrelation functions and the thermodynamic factor. Through models for the direct correlation function, we generalize expressions for the thermodynamic factor to include different electron and ion temperatures, electron degeneracy, finite-temperature exchange, and strong coupling. Additionally, a Gaussian autocorrelation function (GAF) is employed for a binary ionic mixture, yielding a simple analytic transport model for interdiffusion. The GAF model is shown to be accurate for moderately and strongly coupled plasmas.