Modeling of laser-induced breakdown phenomena in non-equilibrium plasmas

This work discusses the modeling of Laser Induced Breakdown (LIB) in gases. The interaction between the laser beam and the plasma is described via a fluid approach based on the Navier-Stokes equations for a gas in Non-Local Thermodynamic Equilibrium (NLTE). The radiation field is split in two components: (i) collimated and (ii) and non-collimated. To model the collimated component (i.e., the laser), a flux-tube formulation of the Radiative Transfer Equation (RTE) is developed. The non-collimated component, representing the radiation from the laser-induced plasma, is described by an optically thin loss model. The flow governing equations are discretized in space using a second-order finite volume method. The system of equations is time-integrated by a point-implicit dual-time-stepping method. Applications consider the breakdown stage and the early post-breakdown evolution in oxygen plasmas.