Stopping power of a helium plasma under LTE or NLTE conditions

Abstract

In this work, the stopping power of a partially ionized helium plasma due to its free and bound electrons is analyzed for an electron temperature and density in which local thermal equilibrium (LTE) or non-local thermal equilibrium (NLTE) regimes can be possible. In particular by means of collisional-radiative models, the average ionization of the plasma as well as the abundances of different helium species (HeI, HeII, and HeIII) are analyzed in both LTE and NLTE thermodynamic states. The influence of this ionization and of the different ion abundances on the stopping power of the helium plasma is shown to be quite significant. Finally, our theoretical model is compared with experimental results on slowing down of swift argon ions in helium plasma.

Contrasting ion stopping models at medium energies in partially ionized plasmas

“…Using the plasma parameters mass density ρ and temperature T , the plasma ionization state q can be calculated by means of local thermal equilibrium [10,11]. Knowledge of the plasma ionization state q is necessary to estimate the density of free n f e and bound electrons n be , which is relevant for the calculation of plasma stopping power.…”