Temperature measurement of an atmospheric pressure arc discharge plasma jet using the diatomic CN (BΣ+2-XΣ+2, violet system) molecular spectra

Abstract

The CN (BΣ+2-XΣ+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.