Modeling of ionization composition in argon plasma with fast electrons

Discharge and laser produced plasmas often have non-equilibrium electron distributions containing fast electrons that may have a profound effect on the ionization balance. The influence of high energy electrons on the ionization balance in the collisional-radiative equilibrium model for optically thin plasma is considered forthwith. A nonmaxwellian electron distribution with fast electrons at energies and concentrations is used for calculating collisional rates; this according to the Hartree-Fock-Slater (HFS) quantum-statistical model in the average atom approximation. The calculative approach is based on the distorted wave approximation along with numerical and semiclassical wave functions calculated in the self-consistent HFS potential. The results from ionization equilibrium modeling in argon plasma at temperatures T ∼ 5–1000 eV with fast electron energies ranging from 1 to 10 keV and their different relative concentrations (from 0.1–10%) are analyzed. It is shown that fast electrons increase the impact ionization rates and significantly change the ionization stage as compared with equilibrium plasma.