Reduced-order modeling of plasma ionization due to multifluid, collisional-radiative effects

Abstract

Collisional rate calculations which account for relative multifluid streaming were implemented in a collisional-radiative model that is applicable for a generalized set of atomic elements. The rate modifications for multifluid streaming were derived in two recent studies for electron-impact excitation, de-excitation, ionization, and recombination [H. P. Le and J.-L. Cambier, Phys. Plasmas 22, 093512 (2015); 23, 063505 (2016)]. This study follows from the previous studies by extending the derivations to radiative recombination. However, the memory intensive aspect of expanding the collisional rate tabulations to temperature and multifluid effects can become a numerical obstacle for large-scale plasma simulations. The main objective of this study is to explore reduced-order modeling approaches for collisional-radiative systems that may adopt collisional rate accounting for multifluid streaming. The ionization test case simulated in this work uses the quasi-steady-state solution and two Boltzmann grouping approaches, one of which is the ionic excitation concept and the other being a relatively finer selection of Boltzmann groups. The reduced-order models captured the general trend of the detailed model, providing a foundation from which to improve or perform coupled plasma simulations in the future.