An effective potential theory for transport coefficients across coupling regimes

Summary form only given. The microscopic dynamics of Coulomb collisions determines macroscopic transport properties of plasmas such as diffusivity, resistivity, viscosity, etc. Conventional plasma kinetic theories assume that since Coulomb interactions are long range, the momentum transferred in the majority of binary encounters is small. This assumption is used to form an expansion parameter based on the smallness of scattering angles. However, the assumption breaks down in strongly coupled plasmas, where the interaction potential energy is comparable to the particle kinetic energies. These include dense plasmas (ICF, white dwarfs, giant planets, etc.), dusty plasmas and ultracold plasmas. We discuss a method that extends conventional plasma theories to stronger coupling regimes. Like the conventional theories, ours is based on a binary collision picture, but where particles interact via an effective potential¹ that accounts for average effects of the intervening medium; including both correlations and screening self-consistently. The hypernetted chain closure is used to calculate this effective potential. The theory is shown to compare well with classical molecular dynamics simulations of temperature relaxation in electronion plasma,² as well as simulations³ and experiments⁴ of self-diffusion in one component plasma. This analysis applies a static effective potential. Possible refinements to account for a dynamic effective potential will also be discussed.