Diagnosis on the Molecular Vibrational Temperature of a Micro-Plasma Jet Operated at Atmospheric Pressure

In this paper, an optical diagnostic system is used to measure the molecular vibrational temperature of a micro-hollow cathode device. The micro-hollow cathode discharge setup can generate micro-plasma plume in the flowing mixture of Ar and N₂ at atmospheric pressure. The characteristics of the micro-plasma jet have been investigated by means of optical method and electrical one. Optical emission spectrum from the micro-hollow discharge device is given. It has been found that breakdown occurs in the gas between the two electrodes when the input power of electric source is increased to a certain value. Plasma appears along the gas flow direction when the mixed gas flows from the aperture of the micro-hollow cathode, and the length of plasma reaches 4mm. The duration of discharge pulse is about 0.15μs. Molecular vibrational temperature has been estimated by Boltzmann plot method. It is found that, the molecular vibrational temperature is bout 4000K. It can also be found that, the molecular vibrational temperature is almost independent of power in the error range. A qualitative explanation to the phenomenon is given based on the gas discharge theory.