Thomas-Fermi model for dense plasmas.

Abstract

The average degree of ionization for a dense plasma is calculated with the aid of a newly established atomic model based on the Thomas-Fermi (TF) method. This new model is characterized by the following features: (i) the bound electrons and free electrons are treated separately, (ii) a physically reasonable definition of the bound electrons is given, (iii) the system is described as a strongly coupled plasma of free electrons and TF ions, (iv) the source density in the Poisson equation is determined by the electron-ion and ion-ion correlation functions, and (v) the degree of ionization is calculated through the minimization of the total free energy. Results from the first and second approximations are presented, corresponding to models of increasing sophistication for the ion-ion correlation function. A comparison of these results with the results from earlier TF calculations and with the results from the Saha equation is also provided.