Pair Correlation Functions of Strongly Coupled Two-Temperature Plasma

TL;DR

This study uses molecular dynamics simulations to evaluate and validate models for pair correlation functions in strongly coupled two-temperature plasmas with species of unequal temperature, focusing on the SVT and Seuferling-Vogel-Teopffer models.

Contribution

First direct testing of three extended Ornstein-Zernike/hypernetted-chain models for two-temperature plasmas with unequal species temperatures, validating the SVT model's accuracy.

Findings

Seuferling, Vogel, and Teopffer model agrees well with simulations across various parameters.

SVT model accurately predicts interspecies correlation strength and static structure factors.

Yukawa OCP model describes ion-ion correlations well up to a certain coupling strength.

Abstract

Using molecular dynamics simulations, we perform the first direct tests of three proposed models for the pair correlation functions of strongly coupled plasmas with species of unequal temperature. The models are all extensions of the Ornstein-Zernike/hypernetted-chain theory used to good success for equilibrium plasmas. Each theory is evaluated at several coupling strengths, temperature ratios, and mass ratios for a model plasma in which the electrons are positively charged. We show that the model proposed by Seuferling, Vogel, and Teopffer [Phys. Rev. A 40, 323 (1989)] agrees well with molecular dynamics over a wide range of mass and temperature ratios, as well as over a range of coupling strength similar to that of the equilibrium HNC theory. The SVT model also correctly predicts the strength of interspecies correlations and exhibits physically reasonable long-wavelength limits of the static structure factors. Comparisons of the SVT model with the Yukawa OCP model are used to show that ion-ion pair correlations are well described by the YOCP model up to $\Gamma_e \approx 1$, beyond which it rapidly breaks down.