Computational and experimental study of ionic space charge generated by combined corona-electrostatic electrode systems

Numerical computation of the electric field intensity and space charge density in electrode systems consisting of ionizing and nonionizing elements, connected at a same DC high-voltage supply and facing a grounded plate, is a difficult problem, which is of interest to several electrostatic processes applications. The aim of the present paper is to demonstrate the effectiveness of an original method of field computation in the analysis of the factors that influence the distribution of the ionic space charge in such combined corona-electrostatic electrode systems. The computations and the experiments were carried out for an ionizing wire of diameter 0.3 mm, located at different distances h (10 to 30 mm) from a tubular support of diameter 25 mm. Several inter-electrode distances (20 to 45 mm) were simulated. The extension of the zone at the surface of the grounded electrode which is affected by the space charge diminishes when reducing the intervals between these elements of the electrode system, and - at similar applied voltage - the density of the corresponding corona current increases. The experimental data were in good agreement with the computed results, validating the accuracy of the numerical method of space-charge calculation in this special electrode configuration.