[Study on energy transfer in argon/air in dielectric barrier discharge by optical emission spectra]

The energy transfer in dielectric barrier discharge in argon/air mixture in a device with water electrodes was investigated by comparing the optical emission spectra in pure argon, argon/air mixture and air. It was observed that the intensities of argon spectral lines in argon/air discharge are all lower than that in argon discharge, which indicates that the nitrogen in air has a quenching effect on the argon excited states. It was found that the decreasing rate of intensity of spectral lines with increasing the air concentration is different. The intensity of ArI 763. 51 nm decreases fastest, the ArI 772.42 nm and ArI 696.54 nm take second place, while the ArI 750.39 nm decreases slowest. Comparing the excitation energy of argon excited state with the excitation energy of nitrogen molecule, the authors found that the smaller the difference between the excitation energy of argon excited state and the excitation energy of nitrogen molecule, the faster the spectral line decreases, implying the stronger the energy transfer. In addition, the additional argon in air makes the emission intensities of nitrogen band of second positive system and band of first negative system increase, which indicates that the excitation of nitrogen is enhanced by the energy transfer from argon through Penning excitation involving argon metastable states. In other words, the component and ratio of gas in the gas mixture influence the optical characteristic and energy transfer peculiarity in the mixed gas discharge. The optical emission spectra measurement as a useful plasma diagnostic tool has been successfully used in the study of energy transfer in the mixed gas discharge, and the results provide a reasonable reference for the underlying industrial applications of different species discharge.