Charging and heat collection by a positively charged dust grain in a plasma

Abstract

Dust particulates immersed in a quasineutral plasma can emit electrons in several important applications. Once electron emission becomes strong enough, the dust enters the positively charged regime where the conventional Orbital-Motion-Limited (OML) theory can break down due to potential well effects on trapped electrons. A minimal modification of the trapped-passing boundary approximation in the so-called OML$^+$ approach is shown to accurately predict the dust charge and heat collection flux for a wide range of dust size and temperature.