Ionization Processes in a Negative Needle‒Plane Electrode System: Experiment

Ionization processes in air are studied: corona discharge with strongly and weakly pointed electrodes with a high-voltage active negative potential. The primary focus is on the influence of surface and degradation processes on corona electrodes. The current–voltage characteristics were measured in the vicinity of the ignition voltage of the corona discharge and the problem of experimental identification of surface charges is studied. The distribution of ions is estimated based on the glow color of ionization zones and the integral spectrum of the corona discharge. The dark current at the corona-forming, slightly curved negative electrode is explained by the capture of surface electrons by electron-accepting oxygen molecules. It is concluded that the mechanism of surface electron ionization is the same both in the dark region in air (in standard conditions) and in solutions of liquid dielectrics with iodine, in which the current–voltage characteristic is determined by the capture of surface electrons by iodine molecules.