Probe Research of the Cathode Region of the Glow Discharge

An experimental investigation of the ion fluxes to the cathode of the glow discharges in nitrogen has been performed and is presented in this work. These were studied in a discharge tube with flat electrodes. A hole closed by a grid was located in the cathode center. Next to the hole, a collector was mounted. The study was conducted in nitrogen at discharge currents of 2.5-10 mA and gas pressure 0.3-3 Torr. The dependence of the collector current on the potential difference between the collector and the cathode was determined. In all cases, the voltage blocking (the collector current is equal to zero) is much less than the total voltage across the tube, which can be taken as the value of the cathode fall. The maximum energy of ions reaching the cathode significantly depends on the gas pressure. The alteration of the discharge current at a constant gas pressure does not affect the blocking voltage and the energy distribution of ions. The ion energy distribution functions were determined from the experimental characteristics. The analysis of the ion distribution functions shows that the main process determining the ions energy distribution is charge-exchange.