A SIMPLE ANALYTIC ALTERNATIVE TO WARBURG LAW

A point-plane corona discharge in ambient air is modelled by regarding the drift of ions from the coronating point-electrode to the earthed plane as a succession of non-interacting uniform spheres of charge. Each sphere is thought to expand in its self-field as it drifts in the mean field between point and plane. The space charge deposited by the spheres on their arrival at the plane implies a current distribution which gives an analytic alternative to Warburg's empirical expression. It is shown that the parameters of the model can be adjusted to give a good fit to experimentally obtained results for negative coronas. The success of this simple model is discussed in terms of experimental observations and recent theoretical developments. © 1990 IOP Publishing Ltd.