Analytical model for determination of the unipolar ionic saturation current during positive corona discharge for geometries comprising cylindrical emitter electrodes

This paper presents an analytical model for the assessment of the unipolar corona saturation current limit for positive corona discharge in air, based on the determination of the field line lengths and trajectories. The model is applicable to emitter electrodes with a cylindrical surface facing a plane or an identical cylindrical collector electrode, if their spatial characteristics, the ion mobility of the surrounding medium and the applied voltage are known. Experimental investigation is performed to compare the results of the unipolar corona saturation current limit from the proposed model to the actual corona current flow in an experimental setup that comprises cylindrical emitters of various radii, facing a plane electrode. Both the total current amplitude and the current density distribution over the collecting electrode's surface have been examined.