Electric fields coupled with ion space charge. Part 2: computation

Abstract

The coupled computation of the electric field distribution together with ion space charge is considered for the case of a point-plane arrangement, where ions are induced by a high-voltage needle. The general physical problem and its numerical implementation are focused as well as the usage of Peek's Law. The computations, which are destined for coupling with flow field simulations, are performed with a modified commercial CFD-Tool (FLUENT), based on the finite volume method. The numerical results are compared with experimental ones performed by means of the set-up presented in Meyer et al. (Electric fields coupled with ion-space-charge: I. Measurements, Electrostatics, 2005, accepted for publication). The results obtained are problematic, and therefore this method is limited to coupled simulation, if only a rough estimation of the electric field is needed or if a complex geometry avoids measurements. Additionally, the influence of ion wind is tested as well as different meshing techniques, which are all found to be of minor importance for the simulation of this arrangement.