Eur. Phys. J. D 47, 83-105 (2008)
https://doi.org/10.1140/epjd/e2008-00035-1

Charging of a conducting sphere moving in a weakly ionized gas under an arbitrarily oriented external uniform electric field

Institute of Applied Physics RAS, Ulianova str. 46, 603950 Nizhny Novgorod, Russia

Corresponding author: ^a and@appl.sci-nnov.ru

Received: 12 October 2007
Revised: 4 January 2008
Published online: 29 February 2008

Abstract

A charging conducting sphere moving in a weakly ionized gas is investigated. An external uniform electric field is applied with arbitrary orientation relative to the gas flow. The ion current is obtained analytically and investigated numerically in ballistic assumption. It is shown that charging regimes depend not only on the net charge of the sphere but also on the gas flow type, and the parameter ξ_± – the ratio of ion drift velocity far from the sphere to the gas velocity. The cases |ξ_±|<1 and |ξ_±|>1 yield two different charging regimes for Stokes and potential flows. For the potential flow, the ion current has been found analytically in continuous ξ_±-parameter space. The stationary charge of an isolated sphere is also calculated numerically as a function of α. It achieves maximum magnitudes in direct (α=0) and back (α=π) flows respectively.