Numerical modeling of laser-produced blast waves in real gases

A fast pulsed laser focused into a gas target deposits its energy into a small volume and generates a shock wave that dissociates and ionizes the gas. A numerical model of the propagation of the blast wave is described here. The computation includes several realistic gas properties such as internal energy for vibration, dissociation, ionization and electronic excitation of the molecules and atoms, as well as conductive and radiative heat-transfer. This model uses the method of characteristics with the initial and boundary conditions computed from a self-similar solution, following a technique proposed by Steiner and Gretler (1994) [1]. The modeling described here is programmed in Mathematica. While this is a powerful language for evaluating complex analytical expressions, its use in numerical modeling poses several technical problems. The methods and results of these calculations are described and compared to a simple self-similar blastwave in a molecular gas without dissociation. A general Mathematica program for calculating conditions in a blastwave is given in the appendix.