The one atmosphere uniform glow discharge plasma (OAUGDP) as a classical normal glow discharge

Abstract

Summary form only given, as follows. The one atmosphere uniform glow discharge plasma (OAUGDP) operating in air and other gases, has been recently developed at the UTK Plasma Sciences Laboratory and is proprietary to the University of Tennessee. The plasma is driven at low RF frequency, on the order of a few kilohertz, and is formed in a relatively large gap (several mm in air), between plane parallel insulated metal electrodes. For the proper values of gap distance, RF driving frequency, and rms voltage, the OAUGDP operates uniformly, without producing filamentary microdischarges, and its physical characteristics are, in spite of the high pressure, surprisingly analogous to those observed in a normal DC glow discharge. Numerical simulations and experimental time-resolved photographs show that all the features of the classical normal glow discharge are present between the instantaneous cathode and anode: the cathode dark space, a linear electric field in the cathode region obeying Aston's law, the negative glow, the Faraday dark space, and the positive column. The glow discharge nature of the OAUGDP is significant because normal glow discharges operate very efficiently as plasma sources at or near the Stoletow point where the energy cost of generating an ion-electron pair in air is only 81 eV. In other atmospheric plasmas, such as arcs, this energy cost can be at least 10 KeV per ion-electron pair. We have developed a variety of configurations for the electrodes which permits both large and small processing volumes and allows a large range of applications to be accommodated. The electrical and physical characteristics of the OAUGDP will be presented.