Computer Simulation of Laser-Induced Shock Wave Propagation in Gas

Abstract

Computer simulation is carried out to study the propagation processes of blast wave induced by laser-produced plasma in air. One-dimensional Euler equation is solved numerically by a finite discrete method. Real gas effects are taken into account based on the assumption of local-thermodynamic equilibrium (LTE) where the electron and heavy particle temperatures are assumed the same and the chemical equilibrium holds at every point. Rarefied gas region is formed between the shock wave front and the plasma core, and the plasma core decays at the time scale of msec. In order to examine the validity of the LTE assumption, the radiation spectrum from the plasma core is calculated and compared with the experimental data. The simulation code underestimates the electron temperature and density during 10μsec after the laser plasma ignition because in reality the electron temperature is still higher than the heavy particle temperature. However, as the plasma approaches the equilibrium state after 10μsec, the simulation results show a good agreement even quantitatively with the experimental results.