Non-local Thermodynamic Equilibrium Effect On Opacity,

In this paper, we define non-equilibrium coefficients of plasma to describe the departure from local thermodynamic equilibrium(LTE). These coefficients cannot only help us to determine the departure from LTE accurately but can also be used to calculate LTE criteria. The numerical examples show the reasonableness of these coefficients and the LTh criteria curves for different elements are very interesting. The NLTE average atom model(AA) is improved by accounting the RP and EA processes. Few AA model includes such two-electron processes until recently a new AA model is developed. The present method to include such processes is different from the other one and has its own advantage to avoid the two-electron correlation. The comparison of the results of the two models shows poor agreement, which calls for further study on such processes under AA model. The opacity due to scattering at high temperature is studied for NLTE plasmas. It is the first time to take into account both non-Thomson cross-section and the NLTE effects on scattering opacity. The results show that the high temperature modification for scattering cross section is less than 30% for electron temperature lower than 10 keV. The average ionization stages calculated by the improved AA model agree well with those calculated by other accurate detailed configuration accounting(DCA) models. However, the charge state distributions calculated from the AA model by binomial distribution are much different from those of DCA models, especially for high-Z elements. This implies that the two-electron correlation in NLTE condition should be accounted. Using these improved AA model, The NLTE opacity is calculated and the ionization temperature method is also checked. The results show that the NLTE effects on opacity is strong and the ionization temperature method is reasonable for calculating opacity. Our results of Rossland mean opacity and the ionization temperature agree well with those of SCROLL.