Investigations of DC corona and back discharge characteristics in various gases

The paper presents investigations of forward and back discharges occurring in air, carbon dioxide, and nitrogen, with plate electrode covered with fly ash. For the glow discharge, the back corona current is lower than for normal corona discharge, but for back-arc discharge, both currents are nearly the same. A dielectric layer covering the plate electrode causes that the arc discharge can start at higher voltages. In the arc discharge, the elements present in fly ash can volatilise due to electron bombardment of the layer.