Classical molecular dynamic simulations and modelling of inverse-bremsstrahlung heating in low Z weakly-coupled plasmas

TL;DR

This study uses classical molecular dynamics simulations to investigate inverse-bremsstrahlung heating in low Z plasmas, challenging existing models and proposing a refined parameterized model that accurately fits simulation data.

Contribution

The paper introduces a comprehensive parameterized model with six adjustable constants that accurately describes inverse-bremsstrahlung heating, validated against extensive molecular dynamics simulations.

Findings

Past models' Coulomb logarithms depend only on laser frequency, not intensity.

The new model fits all simulation results and previous literature data.

Simulations cover a wide range of electron densities and temperatures.

Abstract

Classical molecular-dynamics simulations (CMDS) have been conducted to investigate one of the main mechanism responsible for absorption of radiation by matter namely stimulated inverse bremsstrahlung. CMDS of two components plasmas (electrons and ions) for a large range of electron densities, electron temperatures, for ionization $Z=1$, were carried out with 2 million particles using the code LAMMPS. A parameterized model (with 6 adjustable constants), which encompasses most theoretical models proposed in the past to quantify heating rate by stimulated inverse bremsstrahlung, serves as a reference for comparison to our simulations. CMDS results are precise enough to rule out elements of these past models such as coulomb logarithms depending solely upon laser pulsation $\omega$ and not upon intensity. The 6 constants of the parameterized model have been adjusted and the resulting model matches all our CMDS results and those of previous CMDS in the literature.