Preliminary results of the research on one atmosphere glow discharge

Abstract

Summary form only given, as follows. A device for producing a glow discharge plasma at one atmosphere was built and tested. The discharge, powered by an AC source capable of providing a few tens of kV voltage with a few kilohertz frequency, was generated between two plane electrodes covered with 3 mm Pyrex insulating plates. The diameter of the electrode varies from 5 to 15 cm and the gas gap from 2 to 5 mm. The experiments confirmed that it is much easier to obtain one atmosphere uniform glow discharge (OAUGD) in He than in the air. OAUGD could be easily produced in a 5 mm helium gap with an applied voltage, Va, of 1.4 kV rms at a frequency, f, from 1.1 to 5 kHz, while it could only be observed in an air gap shorter than 2 mm with a much higher Va at a much more narrow f range. The glow discharge current is characterized by one peak per half cycle, which begins to appear at the time short after the polarity inversion of the sinusoid-like applied voltage and lasts a few tens us. The current peak varies from some mA to a few tens mA, depending on Va's amplitude and frequency. Comparing to that in a 5 mm helium gap, the discharge in a 5 mm air gap behaves much differently. When Va 2.5 kHz and a much deformed capacitive current for f<1.5 kHz were found, the later most likely means gas discharge occurring in the gap, but no light from discharge could be seen with the naked eye. When Va rose up to 18 M filamentary discharge was observed and several discharge current peaks with a duration of about 10 ns were found superposed on the capacitive current top.