Towards a microscopic theory of particle charging

TL;DR

This paper introduces a surface-based microscopic model for dust particle charging in plasmas, challenging traditional flux-balance approaches and aligning well with experimental data.

Contribution

It presents a novel microscopic surface model for dust charging that incorporates boundary physics and differs from standard flux-balance models.

Findings

Model agrees with experimental charge measurements

Provides detailed hypotheses on grain boundary physics

Offers an alternative to flux-balance charging theories

Abstract

We recently questioned the treatment of a dust particle as a perfect absorber for electrons and ions and proposed a surface model for the charge of a dust particle in a quiescent plasma which combines the microscopic physics at the grain boundary (sticking into and desorption from external surface states) with the macrophysics of the discharge (plasma collection fluxes). Within this model the charge and partial screening of the particle can be calculated without relying on the condition that the total electron collection flux balances on the grain surface the total ion collection flux. Grain charges obtained from our approach compared favorably with experimental data. The purpose of this paper is to describe our model in more detail, in particular, the hypotheses on which it is built, contrast it with the standard charging models based on flux balancing on the grain surface, and to analyze additional experimental data.