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

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 ω 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. II. THEORETICAL MODELING FOR INVERSE BREMSSTRAHLUNG ABSORPTION IN THE LITERATUREClassical solutions to this problem have been provided through different techniques in the literature. The oldest was by way of ballistic modeling as in Landau [1] or Mulser [7] where one considers the trajectory of one single