Binary phase separation in strongly coupled plasma

We investigated the two-dimensional binary phase separation process of plasma species using classical molecular dynamics in the strongly coupled regime. Both the plasma species interact via a pairwise screened Coulomb (Debye-H & uuml;ckel) potential; however, the screening parameter kappa is different for like- and unlike-species and is the cause for phase separation. We characterize the separation process by measuring the domain growth of equilibrium phases as a function of time-generally, the more significant the inhomogeneity in pairwise interaction, the faster the domain growth. Typically, the domain growth follows a power law in time with an exponent beta characterizing the underlying coarsening mechanism. We demonstrate that the growth law exponent is beta=1/2 for equal-number-density mixtures and 1/3 otherwise. Further, by comparing these with the corresponding growth laws in binary mixtures of viscous fluids, we show that the viscoelastic nature of plasma fluid modifies the coarsening dynamics, which in turn leads to the observed growth law exponents, notably in the unequal-number-density case.