Comparison of electron-ion energy transfer in dense plasmas obtained from numerical simulations and quantum kinetic theory

TL;DR

This paper compares various analytical models and molecular dynamics simulations to understand electron-ion energy transfer in dense plasmas, highlighting the regimes where collective mode effects are significant or negligible.

Contribution

It evaluates multiple models for electron-ion energy transfer against MD simulation data, clarifying when collective mode effects are relevant or can be ignored.

Findings

Most MD data show no clear collective mode effects.

FGR and binary collision models are sufficient in many regimes.

Parameter regimes, like initial temperature difference, influence the prominence of collective modes.

Abstract

We evaluate various analytical models for the electron-ion energy transfer and compare the results to data from molecular dynamics (MD) simulations. The models tested includes energy transfer via strong binary collisions, Landau-Spitzer rates with different choices for the cut-off parameters in the Coulomb logarithm, rates based on Fermi's golden rule (FGR) and theories taking coupled collective modes (CM) into account. In search of a model easy to apply, we first analyze different approximations of the FGR energy transfer rate. Then we investigate several numerical studies using MD simulations and try to uncover CM effects in the data obtained. Most MD data published so far show no distinct CM effects and, thus, can be interpreted within a FGR or binary collision approach. We show that this finding is related to the parameter regime, in particular the initial temperature difference, considered in these investigations.