Resumen de Axisymmetric computational modelling of a laser induced air plasma

Eric Schall, S. Soubacq, P. Pignolet

• Recent developments in pulsed high voltage technologies used in some great scientific facilities (i.e. the Méajoule laser, or X radiation generator,. . . ), have presently a large revival of interest for triggering methods. Because of numerous advantages (lowering of d.c. breakdown voltage, accuracy of shot control, variable delay without jitter, complete insulation between the triggering system and the high power electrical circuit,. . . ), one of these consists in the use of laser triggered switches. As the relevant laser triggering is physically based on the laser induced gas breakdown process involving a plasma generation which sharply depends on complex experimental conditions (gas pressure, radiative absorption conditions,. . . ), it is of a great importance to investigate the dynamic evolution of that phenomenon under that parametric influence. Thus, a numerical twodimensional compressible flow simulation of the plasma expansion induced in air by a focused Nd:YAG laser beam is proposed. A modelling of the dynamic phase of laser plasma is presented. This phase, described as a strong shock wave expanding out of the focal volume, is simulated by using a two-dimensional compressible flow calculation code. The evolution of pressure, temperature, densities and velocities are analysed