BACK IONIZATION IN A NEGATIVE POINT-TO-PLANE CORONA DISCHARGE

Back ionization from porous layers of tissue paper on the plane of a point-to-plane corona discharge has been studied by observing light emission from the layer and from the point and by detecting the associated current pulses in the external circuit. A quasi-continuous low level light emission was detected from all paper surfaces. It is proposed that this glow emanates from a discharge which is the source of a steady current of positive ions which is responsible for the increase in Trichel pulse frequency; this in turn accounts for nearly all the increase in the current in the external circuit during back ionization. Three types of pulsed light enmission were also detected. This work is relevant to electrostatic precipitation and powder coating.