Modeling results on the dust charge distribution in a plasma afterglow

Abstract

Discharging of dust particles in an argon plasma afterglow is investigated using different approaches. First, the dust charge distribution function (DCDF) is obtained by solving numerically the master equation describing dust discharging as a one-step stochastic process. Second, the DCDF is calculated as a Gaussian distribution with mean dust charge and variance, which are functions of time. Additionally, the time-dependencies for the mean dust charge are obtained assuming that the charge changes continuously in the afterglow plasma. Calculation results are compared with available experimental data and are found to be in good qualitative agreement if the dust discharging model accounts for the emission of electrons in the collisions of excited argon atoms with dust particles. This study is carried out taking into account the transition from ambipolar to free diffusion as well as multistep ionization, excitation, and deexcitation of argon atoms in the plasma afterglow.