Transition of discharge mode of a local hollow cathode discharge

The discharge characteristics of hollow cathode discharge in argon in a cylindrical cavity are investigated experimentally. The voltage-current (V-I) characteristics and the light emission are measured. It is found that the discharge plasma is localized inside the hollow cavity, withan extensive Faraday dark space between the cathode and the anode. The discharge develops from predischarge to abnormal glow discharge, the hollow cathode effect (HCE) and a hybrid mode as the discharge current increases. The onset of the HCE is found for the first time by the transition from abnormal glow discharge together with a significant decrease in the slope of the V-I curve which shows a positive differential resistivity. The voltage increases proportionally with the current when the HCE is reached.