Non-LTE superconfiguration collisional radiative model

We have developed a non-LTE collisional radiative model which takes into account the overwhelming multiplicity of excited levels of heavy elements in hot and dense plasmas. The model, 'SCROLL' (Super Configuration Radiative cOLLisional), treats superconfigurations as effective levels and reproduces detailed configuration accounting results by an iterative procedure which splits superconfiguration until convergence. The fundamental assumption in the model is that within a superconfiguration levels are populated according to Boltzmann statistics. This assumption is effectively relaxed by the convergence procedure. The populations of the superconfigurations are obtained by solving the set of collisional radiative rate equations. For this purpose we have derived analytical formulae for the average transition rates between superconfigurations for collisional excitation and ionization, radiative transitions, photoionization and autoionization. These analytical formulae are obtained using the 'Partition Function Algebra' developed in our previous LTE STA model. The calculation of the average rates are performed in the distorted wave approximation framework. Using the resulting superconfiguration populations we can then calculate charge distribution, opacities and emissivities. The model is applicable to any atom. In the present work it was applied to investigate non-LTE thin plasmas of Al and Au for several temperatures and densities. Comparison with detailed calculations when these are possible gave excellent agreement. Both theory and results are addressed. (C) 1997 Published by Elsevier Science Ltd. All rights reserved.