Enhanced efficiency of atomic oxygen generation in a single-electrode, 5NS pulsed microplasma jet

Abstract

A single-electrode, 5 millimeter long, 500 micrometer-in width, helium plasma jet was generated in ambient atmosphere when the electrode was excited with 5 ns, 8 kV pulses at 500 Hz. Optical emission spectroscopy (OES) showed that the production of excited atomic oxygen increased by a factor of 2 for the 5 ns pulsed plasma jet when compared with that for a 164 ns pulsed plasma jet operating at the same voltage, amplitude, and flow conditions. This signifies an enhanced efficiency of atomic oxygen production using the 5 ns pulsed plasma with faster rise time, as the energy per pulse was 0.12 mJ, which had only 8 % more energy per pulse than that of the longer pulsed version. Emission due to excited species including He, O, H, OH, N 2 (C-B) and N 2 + (B-X) were observed in both of the discharges within the first 1 mm (from the tip of the electrode) of the jet. All of the emissions, except from that of N2 second positive system, decayed rapidly with the distance. Analysis of the rovibronic emission from N2 (CB) showed both the nanosecond plasma jets have a rotational temperature of 300 K and a vibrational temperature of 3000 K.