Determination of the charge-state distribution from effective iontemperatures in non-LTE plasmas

Abstract

We propose a global method for rapid calculation of charge-state distributions, which relies on effective ionic-excitation temperatures T( I) for each of the ions in a hot, quasi-steady-state non-LTE plasma. An analytic formula is given for obtaining T( I) as a function of a few rates of atomic processes. Thus, an internal partition function can be written for each ion. A formula is proposed for the ratio of the total populations of two ions with neighboring charges, replacing the Saha equation, which is not a valid description of non-LTE plasmas. The charge-state distribution and the 〈 Z〉 value are deduced. Very good agreement is found in the comparison of the results obtained using this method with some experimental results on gold plasmas, and also with theoretical values computed through the resolution of complete collisional–radiative systems.