Influence of plasma ions on the stopping power and the energy straggling of charged particles traversing hot plasmas

Abstract

A charged test particle moving through a plasma suffers the effects of collisions with the plasma particles. The effects of these interactions may be described in terms of the two main energy-loss parameters, namely, the stopping power and the energy-loss straggling; these are the main parameters that characterize the interaction of external particles with the plasma. Here we perform a comparative study of the ionic and electronic contributions to the stopping and the straggling for the hydrogen isotopes, alpha particles, positrons, and muons, traversing different types of plasmas: tokamak plasmas, the dense helium region of a giant star, and the solar interior. To calculate these parameters we apply a quantum approach to describe the interaction of charged particles with plasmas, based on one side on the quantum dielectric plasma model, which includes a full description of statistical effects on energy exchange processes together with a quantum treatment of electron excitations. In addition, we incorporate the effect of the plasma ions through a semiclassical dielectric function that combines a quantum description of plasma electrons with a classical dielectric model for plasma ions. Through various examples we analyze the partial (electronic and ionic) and total contributions to the stopping power and energy straggling for protons, positrons, and muons. The comparison between these cases provides insights into the effects of statistical fluctuations and ionic contributions to the energy-loss processes for each of these particles and different plasma media.