On the interaction of adjacent coronae: a description of the electric field behaviour on the planar line beneath twin coronating negative DC points in air

A full mathematical description of the complex interaction of adjacent point-plane coronae has yet to be given. An essential feature of the phenomenon is the electric field on the planar line running directly below the points. Experimental data, obtained elsewhere, have been manipulated to reveal the functional dependence of this field on the control or independent variables of voltage and geometry. A model in terms of simple functions has then been derived that fits the measurements within reasonable bounds and which is a valuable tool from the point of view of predictive engineering. As for single points, the behaviour is shown to be separable, with a linear dependence on the voltage and an inverse dependence on the gap separation. The distribution is further shown to be represented by cosine power functions of the angles subtended from each planar position to the electrode points and to locations on the central axis between the points. The modelling uses centre-of-charge concepts, and gives an insight to the mutual interactions of the multipoint discharges that are used commercially and also into the behaviour of neighbouring coronas on high-voltage equipment in the environment. What is known of single-point phenomena leads one to expect that the description derived here is likely to hold for a large range of gap sizes and also for positive DC discharges in the absence of streamers.