Temperature measurement of an atmospheric pressure arc discharge

The CN B 2 -X 2 + molecular emission spectrum is used to measure both the vibrational and rotational temperatures in atmospheric pressure arc jet discharges. The vibrational and rotational temperature effects on the synthetic diatomic molecular spectra were investigated from the v ,v = 0,0 band to the 5,5 band. The temperatures obtained from the synthetic spectra compared with the experimental result of a low-frequency arc discharge show a vibrational temperature of 4250–5010 K and a rotational temperature of 3760–3980 K for the input power in the range of 80–280 W. As the 0,0 band is isolated from other vibrational transition bands, determination of the rotational temperature is possible based only on the 0,0 band, which simplifies the temperature measurement. From the result, it was found that the CN molecular spectrum can be used as a thermometer for atmospheric pressure plasmas containing carbon and nitrogen. © 2009 American Institute of Physics. DOI: 10.1063/1.3087537