Optical Diagnostics of Breakdown Phase of Pulsed N2/He Atmospheric-Pressure Microhollow Cathode Discharge Plasma

• Published in: Jpn J Appl Phys 2011-08, Vol.50 (8), p.08JB07-08JB07-6
• Main Authors: Wake, Shinya, Nakano, Toshiki, Kitajima, Takeshi
• Format: Article
• Language: eng ; jpn
• ISSN: 0021-4922; 1347-4065
• DOI: 10.1143/JJAP.50.08JB07

The breakdown phase of a pulsed N 2 /He atmospheric-pressure microhollow cathode discharge plasma is studied using the time-resolved N 2 optical emission spectra as well as the discharge current and voltage. The N 2 emission intensity exhibits a sharp peak in the breakdown phase and becomes constant in the glow discharge phase. The temporal variation of the N 2 emission spectra indicates that the N 2 rotational temperature remains below 500 K immediately after discharge ignition but increases to ${\approx}1000$ K within ${\approx}20$ μs after the ignition. In the breakdown phase, the plasma with high excitation and dissociation rates is probably generated at the low neutral temperature. The prompt increase in neutral temperature indicated by the N 2 rotational temperature is explained using a simple, zero-dimension model including the neutral heating due to electron--neutral collisions and the neutral cooling caused by the removal and refilling of the gas in the discharge volume.