The Coulomb logarithm evaluation effects on the inverse Bremsstrahlung absorption (IBA) in laser fusion plasmas

Abstract

Inverse Bremsstrahlung absorption (IBA) in high-temperature laser fusion deuterium–tritium (DT) plasmas is investigated. A comparison between two common models, namely the Spitzer model and the Brown–Preston–Singleton (BPS) model, is made to evaluate the Coulomb logarithm. In this case, the sensitivity of the Coulomb logarithm values and the coronal temperatures on IBA is also studied by utilizing these models, considering quantum effects. Using an efficient numerical method combining the Crank–Nicolson and the Newton–Raphson schemes for solving heat transfer equation, energy absorption from the laser and diffusion in a DT target are simulated. It is shown that the Spitzer model gives larger values for the Coulomb logarithm compared to the BPS model. In addition, the overestimation of the Coulomb logarithm in the Spitzer model considerably decreases the absorption length. Furthermore, with increasing electron temperature, the absorption length shows major discrepancies in the two mentioned models.