STUDY OF THE VALIDITY OF A SHOCK WAVE MODEL TO DESCRIBE THE LASER-INDUCED PLASMA EXPANSION INTO OXYGEN GAS

Abstract

In this contribution, the plume expansion dynamics of an ablated Sm2O3, Nd2O3 and NiO mixed oxide target by a KrF laser into a background of oxygen atmosphere has been investigated using fast ICCD imaging. The laser fluence was fixed at 2 Jcm-2 and the surrounding ambient gas pressure was varied from vacuum to 50 mbar. The imaging data were used to create position–time plots of the luminous front. The plume behaviour was found influenced by the gas pressure above a certain threshold. The plasma plume dynamics was analysed in the framework of a shock wave model. It was found that the shock wave model is valid at distance ranges which depend on the gas pressure. This was very well illustrated using dimensionless variables. By studying the evolution of the plume stopping distance at high pressures and comparing the measured plume mass to the calculated ones, it was found that the previsions of the shock wave model are valid.