Measurement of the rotational temperature during pulsed discharge in atmospheric gas

Pulsed power technology has been used in many applications such as control of NOx and SOx from exhaust gases, treatment of dioxins, removal of volatile organic compounds, generation of ozone, and laser excitation. In this situation, it is well known that the shorter pulse width of applied voltage to discharge reactor improves energy efficiency of the pollutant removal. However, it is still unclear why the shorter pulse brings less energy consumption to treat pollutant. Normally, the heating of medium gas during discharge is thought as one of cause of energy loss. Therefore, in this work, the temperature of medium gas in discharge reactor was measured during pulsed discharge process. As the experimental method, the rotational temperature during the pulsed discharge in atmospheric gas gap was measured by analysis of optical emissions. As the experimental results, the rotational temperature of air is approximately 300 K during the propagation of streamer in the pulsed discharge. On the other hand, the rotational temperature in air increases to approximately 400 K during the glow-like discharge mode in the pulsed discharge. In addition, it is obvious that the nitrogen rotational temperature in the vicinity of the central wire electrode of the coaxial reactor increases higher than that near ground cylinder electrode. From these results, it is clear that the shorter pulsed discharge which has the streamer propagation mainly brings less energy consumption for heating gas. It means that the shorter pulsed discharge can consume energy for radical formations, which react with pollutant, efficiently and can improve the energy efficiency of pollutant removal. In this paper, the spatial and the temporal dependences of the rotational temperature during pulsed discharge would be reported.