Impedance matching for one atmosphere uniform glow discharge plasma (OAUGDP) reactors

Abstract

A characteristic one atmosphere uniform glow discharge plasma (OAUGDP) reactor requires a power supply capable of delivering a few kilowatts at a frequency of 1-10 kHz, and an rms voltage up to 20 kV. The OAUGDP reactor with the plasma energized can be modeled as a capacitor in parallel with a resistor. In addition, the nonideality of the transformer between the radio frequency (RF) power supply and the plasma reactor introduces an imaginary component in its impedance. Thus, the load of the RF power supply, as seen by its output terminals, is highly reactive. An impedance mismatch resulting from the absence of a matching network will cause a large reflected power from the plasma reactor back to the power supply that does not contribute to plasma formation, but requires an expensive overrated power supply. All the impedance matching networks in the existing literature are for the RF or microwave plasma applications under low pressures, and they cannot be applied to the applications of the OAUGDP, which is operated at much lower frequencies and much higher voltages. In this paper, the design theory and experimental results of two types of impedance matching circuits that match OAUGDP reactors to their power supplies will be presented.