Measurements Of Gas Temperature In Microwave Plasma At Atmospheric Pressure By Molecular Emission Spectrometry

In this study, gas temperature measurements of argon, nitrogen, and air microwave plasma are achieved by the molecular emission spectrometry of the $A^{2} \sum ^{+} \rightarrow X^{2} \prod _{r}$ electronic system of OH radical
^{[1, 2]}
, and the gas temperatures at different microwave power and gas flow rate are explored, the axial temperature distributions of nitrogen and air microwave plasma plume are measured. The experimental results show that the microwave plasma core temperature is higher than 2000 K at different working conditions, even up to over 6000 K in air microwave plasma. At the same working condition, the three kind of microwave plasma gas temperature meet $T_{Ar}\, \lt T_{N2}\, \lt T_{Air}$. The gas temperature increases slightly with the increase of microwave power, decreases slightly with the decrease of gas flow overall. The gas temperature of nitrogen and air microwave plasma plume reduces quickly along the axial direction. In order to verify the accuracy of molecular emission spectrometry, the thermocouple is used as a comparison to measure the temperature of the DBD argon plasma. Experiments show that the temperature measurement results of molecular emission spectrometry and thermocouple are very consistent.