M. Klapisch et al., NON LOCAL-THERMODYNAMICAL-EQUILIBRIUM EFFECTS IN THE SIMULATION OF LASER-PRODUCED PLASMAS, Physics of plasmas, 5(5), 1998, pp. 1919-1926
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.