Classical molecular dynamic simulations and modeling 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 mechanisms 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 and electron temperatures, for ionization Z =  1, were carried out with 2 × 106 particles using the code LAMMPS. A parameterized model (with six 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 six 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.