Surface states and the charge of a dust particle in a plasma

TL;DR

This paper studies the surface states of electrons and ions around a negatively charged dust particle in plasma, identifying the particle's charge with electron surface density and confirming findings with experimental data.

Contribution

It introduces a model linking dust particle charge to electron surface states and demonstrates agreement with experimental measurements.

Findings

Electron surface states determine the particle charge.

Ions act mainly as screening charges, not affecting the charge.

Model matches experimental data well.

Abstract

We investigate electron and ion surface states of a negatively charged dust particle in a gas discharge and identify the charge of the particle with the electron surface density bound in the polarization-induced short-range part of the particle potential. On that scale, ions do not affect the charge. They are trapped in the shallow states of the Coulomb tail of the potential and act only as screening charges. Using orbital-motion limited electron charging fluxes and the particle temperature as an adjustable parameter, we obtain excellent agreement with experimental data.