High Pressure Radio-Frequency Microhollow Cathode Discharges

A new field of microhollow cathode discharges is represented by the RF microhollow cathode discharge. So far, the behavior and related physical processes of the RF microhollow cathode discharge are not well investigated. RF microhollow discharges in air at high pressures were investigated under different experimental conditions. The geometry was changed by reducing the cathode hole diameter and the dielectric spacer thickness. By adding a noble gas to air, the influence of additive gases was explored. Additionally, the parallel operation of RF microhollow discharges was investigated. It was shown that stable RF microhollow cathode discharges could only be sustained up to a pressure of 500 mbar in air despite the changes in geometry. By adding a significant amount of noble gas to air it was possible to sustain the RF microhollow cathode discharge up to atmospheric pressures. Parallel operation of the discharge is possible up to a pressure of 500 mbar in air. It was found from the results that the RF microhollow discharge operates in the predischarge mode. Due to the high frequency (1.4 MHz), the hollow cathode discharge mode will be avoided. Based on this investigation a better understanding of the behavior of the RF microhollow cathode discharge is now possible.