Abstract：To enhance plasma applications' effect, plasma's discharge kinetic process must be explored in depth. The rotation temperature is one of the important parameters reflecting the energy transport in the plasma discharge process, which is mainly calculated by the Boltzmann slope method, which is commonly used to calculate the rotation temperature of the plasma in the thermodynamic equilibrium state and has a large error in calculating the rotation temperature of the plasma in the non-thermal equilibrium state. To address this problem, this thesis proposes an analytical method to calculate the rotation temperature using diatomic molecular spectral bands. A needle-ring electrode plasma jet device is used for the experiment, and a plasma jet is formed by discharging a mixture of Ar/Air/CH4 gas into the device with an operating voltage of 10~14 kV. A spectrometer collects the spectral data of the plasma jet at different discharge voltages to calculate the rotation temperature. The OH (A—X), CH (A—X) and N+2 (B—X) emission spectra were selected to investigate the rotation temperature of the Ar/Air/CH4 plasma jet, using the property that the spectral lines in the wavelength interval of the three diatomic molecules, are not affected by the change of vibration temperature. The rotation temperature of the DBD-excited Ar/Air/CH4 plasma jet was obtained by selecting one spectral line every 20 K in the range of ±100 K calculated by the Boltzmann slope method, fitting it to the experimental spectral line, calculating the root-mean-square error obtained from the fit of the spectral line, and analyzing the accuracy of the fit. The root-mean-square error of the rotation temperature, calculated by the Boltzmann slope method obtained in the fit, is higher than the minimum root-mean-square error, and the root-mean-square error can be reduced by 38%. The minimum root-mean-square errors obtained by fitting the OH, CH, and N+2 spectral bands were 4.6, 2.9, and 2.1, respectively, and the results of fitting the N+2 band were 61% lower than the results of fitting the OH band. The results show that calculating the root-mean-square error of spectral line fitting can effectively improve the accuracy of the calculation results, compared with the Boltzmann slope method when calculating the rotation temperature of the plasma in the non-thermal equilibrium state. The accuracy of the calculation results can be further improved by choosing the emission spectrum of the N+2 (B—X) band for fitting to the experimental spectral line.
Key words：Dielectric barrier discharge; Plasma jet; Emission spectrum; Rotation temperature
张文钧，宋 鹏，鞠迎昕，关婷予，纪相彤，韩 朋. 双原子分子发射光谱分析Ar/Air/CH4等离子体射流转动温度研究[J]. 光谱学与光谱分析, 2024, 44(11): 3136-3141.
ZHANG Wen-jun, SONG Peng, JU Ying-xin, GUAN Ting-yu, JI Xiang-tong, HAN Peng. Study of the Rotation Temperature of Ar/Air/CH4 Plasma Jets by
Diatomic Molecular Emission Spectroscopy. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2024, 44(11): 3136-3141.
[1] Liu Z J, Xu H, Zhou C X, et al. Plasma Processes and Polymers, 2019, 16(11): 1970023.
[2] LI He-ping, YU Da-ren, SUN Wen-ting, et al(李和平, 于达仁, 孙文廷, 等). High Voltage Engineering(高电压技术), 2016, 42(12): 3697.
[3] Xia W J, Liu D X, Guo L, et al. Plasma Sources Science & Technology, 2019, 28(12): 47.
[4] Sun M, Chen W G, Zhang Y, et al. Plasma Science and Technology, 2011, 13(4): 470.
[5] Li C L, Deng L H, Zhang J，et al. Journal of Molecular Spectroscopy, 2013，(284-285): 29.
[6] Zheng S, Yang Y, Li X Y, et al. Fuel Processing Technology, 2020, 204: 106423.
[7] Wang B H, Chen L, Liu G M, et al. Physica Scripta, 2023, 98(4): 045612.
[8] PEI Huan, CHEN Lei, WANG Si-yuan, et al(裴 欢, 陈 雷, 王思远, 等). Spectroscopy and Spectral Analysis(光谱学与光谱分析), 2022, 42(7): 2007.
[9] Liu Z J, Liu D X, Xu D H, et al. Journal of Physics D: Applied Physics, 2017, 50: 195203.
[10] Sainct F P, Durocher-Jean A, Gangwar R K, et al. Plasma, 2020, 3: 38.
[11] LIU Zhi-jie, CHEN Min, LIU Ding-xin(刘志杰, 陈 旻, 刘定新). High Voltage Engineering(高电压技术), 2022, 48(10): 4196.
[12] LU Quan-fang, LI Juan-long, YU Jie, et al(陆泉芳, 李娟龙, 俞 洁, 等). Journal of Analytical Science(分析科学学报), 2022, 38(2): 147.
[13] LIU Kun, XIANG Hong-fu, ZHOU Xiong-feng, et al(刘 坤, 项红甫, 周雄峰, 等). Acta Physica Sinica(物理学报), 2023, 72(11): 222.
[14] Han Gookhee, Cho Guangsup. Applied Science and Convergence Technology, 2017, 26(6): 201.
[15] Moon S Y, Choe W. Spectrochimica Acta Part B, 2003, 58(2): 249.
