Corona discharges in asymmetric electrode configurations

The dual electrode, which consists of an ionizing wire in parallel with a metallic cylindrical support, both connected at same high voltage supply, has been extensively studied in relation with various electrostatic applications. In practical situations, the dual electrode may be installed in the proximity of metallic objects that will affect the electric field repartition and, hence, the development of the discharge. The aim of the present work is to analyze the operating conditions of such electrodes in the presence of metallic rods or plates connected at fixed or floating potentials. The Superficial Charge Simulation Method was then employed for the numerical analysis of several electrode arrangements involving a dual corona electrode and a metallic rod parallel to it. The paper also reports the results of current–voltage characteristics and current density repartition measurements for the dual corona electrode alone or in the presence of other bodies at same or floating potential. The proximity of metallic objects leads to the increase of corona inception threshold and shifts the I–V characteristics to higher voltages. The objects at floating potential may reduce the discharge current to very low values, while those energized at the same voltage as the ionizing wire may simply anneal the discharge.