Surface Plasmas Versus Volume Plasma: Energy Deposition and Ozone Generation in Air and Oxygen

The energy deposition and the ozone generation in a shielded sliding discharge were compared with those of a simple surface discharge and a pulsed corona discharge in atmospheric pressure air and oxygen. All discharges were generated by applying 160 ns, high voltage pulses. Under the same conditions, the highest energy deposition per pulse was obtained with the shielded sliding discharge. The energy deposition was lower by a factor of four for the surface discharge plasma and by an order of magnitude for the pulsed corona discharge plasma. Replacing air with the more electronegative oxygen caused a decrease in the deposited energy due to electron attachment. The threshold voltage for plasma formation in oxygen in a shielded sliding discharge was approximately 5 kV, three times less than that of the surface discharge (a parts per thousand yen15 kV) and four times less than that of the pulsed corona discharge (a parts per thousand yen20 kV). A new finding of this study is that, whereas the decrease in energy in the pulsed corona discharge was a parts per thousand yen50 %, and that of the simple surface discharge a parts per thousand yen40 %, it was negligible in the shielded sliding discharge. Since the ozone generation scales with energy density, the results show that plasma reactors based on the nanosecond sliding discharge principle have major advantages in compactness, ignition voltage, and in the use of oxygen, rather than air, compared to surface discharges and corona discharges.