Equilibrium probability distribution of a conductive sphere’s floating charge in a collisionless, drifting Maxwellian plasma

摘要

A dust grain in a plasma has a fluctuating electric charge, and past work concludes that spherical grains in anstationary, collisionless plasma have an essentially Gaussian charge probability distribution. This paper extendsnthat work to flowing plasmas and arbitrarily large spheres, deriving analytic charge probability distributions upnto normalizing constants.We find that these distributions also have good Gaussian approximations, with analyticnexpressions for their mean and variance.