Charge fluctuations for particles on a surface exposed to plasma

TL;DR

This paper introduces a stochastic model for charge fluctuations on dust particles on surfaces in plasma, revealing their steady-state distribution and characteristic timescales related to plasma and particle properties.

Contribution

It presents a novel stochastic framework for understanding charge fluctuations on particles in plasma-surface interactions, including analytical results for steady-state distribution and timescales.

Findings

Charge fluctuations are normally distributed in steady state.

Standard deviation of fluctuations scales with C T_e)^{1/2}.

Time to reach steady state is proportional to C T_e.

Abstract

We develop a stochastic model for the charge fluctuations on a microscopic dust particle resting on a surface exposed to plasma. We find in steady state that the fluctuations are normally distributed with a standard deviation that is proportional to $CT_{e})^{1/2}$, where $C$ is the particle-surface capacitance and $T_{e}$ is the plasma electron temperature. The time for an initially uncharged ensemble of particles to reach the steady state distribution is directly proportional to $CT_{e}$.