Collisional charging of dust particles by suprathermal plasmas. II -- Regularized Kappa distributions

TL;DR

This study investigates how extreme suprathermal plasma particle velocity distributions, modeled by regularized Kappa functions, influence dust grain charging, revealing conditions for positive equilibrium charge under these non-standard plasma states.

Contribution

It introduces the use of regularized Kappa distributions to analyze dust charging, extending previous models to include extreme suprathermal plasma states and comparing two temperature models.

Findings

Extreme suprathermal states can lead to positive dust grain charges.

Regularized Kappa distributions provide a more accurate description of plasma effects on dust charging.

Conditions for positive equilibrium charge are identified under these distributions.

Abstract

We study the effects of the velocity distribution functions of the plasma particles on the equilibrium charge of dust grains, acquired through inelastic collisions of the particles with the grains. This paper is the second in a series of two papers on the subject. Here, we consider the charging process when the plasma particles are statistically described by the recently proposed regularized Kappa distribution functions, which allow for extreme suprathermal states, characterized by extremely low values of the kappa index, previously forbidden to the standard Kappa distributions, whose effects on dust charging were studied in Paper I of this series. We analyse the effects that extreme suprathermal states of the plasma particles have on dust charging and verify conditions for the uncommon result of positive equilibrium charge, employing two different models for the regularized Kappa distributions, one with kinetic temperature dependent on the kappa index, and another where the temperature is kappa-independent.