Ion correlation effect on electron screening of moderately coupled plasma

For moderately/strongly coupled plasmas, modeling of the electron screening effect remains an unresolved problem, owing to the complicated many-body correlations among the surrounding electrons and ions. In this work, we investigate the ion correlation effect on electron screening of moderately coupled plasmas using an atomic-state-dependent electron-screening model. It is found that the electron density around a target ion is significantly enhanced by the ion correlation effect from surrounding ions. By considering this ion correlation effect, the electron density fluctuation induced by the target ion becomes non-spherically symmetric, which causes traditional electron screening models to underestimate the screening effects, especially for moderately/strongly coupled and weakly degenerate plasmas. The present model and findings are validated by molecular dynamics simulations of moderately coupled ultracold neutral plasmas. For moderately coupled plasmas, the Coulomb logarithm is found to decrease by about 10%–30% owing to the ion correlation effect, which should be considered when modeling plasma effects on atomic processes, radiation transport, and thermodynamic properties.