NON LOCAL-THERMODYNAMICAL-EQUILIBRIUM EFFECTS IN THE SIMULATION OF LASER-PRODUCED PLASMAS

Local thermodynamic equilibrium (LTE) breaks down in directly or indir ectly driven laser plasmas because of sharp gradients,energy depositio n, etc. For modeling non-LTE effects in hydrodynamical simulations, Bu squet's model [Phys. Fluids B 5, 4191 (1993)] is very convenient and e fficient. It uses off-line generated LTE opacities and equation of sta tes via an effective, radiation-dependent ionization temperature T-z. An overview of the model is given. The results are compared with an el aborate collisional radiative model based on superconfigurations. The agreements for average charge Z and opacities are surprisingly good, even more so when the plasma is immersed in a radiation field. Some re maining discrepancy at low density is attributed to dielectronic recom bination. Improvement appears possible, especially for emissivities, b ecause the concept of ionization temperature seems to be validated. (C ) 1998 American Institute of Physics.