The Influence of Discharge Capillary Size, Distance, and Gas Composition on the Non-Equilibrium State of Microplasma

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• 作者：Asif Majeed ; Xiaoxia Zhong ; Shaofeng Xu ; Xinhui Wu ; Uros Cvelbar and Zhengming Sheng
• 刊名：Plasma Processes and Polymers
• 出版年：2016
• 出版时间：July 2016
• 年：2016
• 卷：13
• 期：7
• 页码：690-697
• 全文大小：2136K
• ISSN：1612-8869

文摘

The non-equilibrium state of microplasma from the mixture of He and N₂ was studied by exploring the rotational and vibrational temperatures of molecular nitrogen under various discharge conditions. At a varying gap distance of 1–3 mm (with a step of 1 mm) from the exit of the capillary to the water surface, the average rotational temperature of N₂ was found to increase from 983 to 1250 K while the corresponding vibrational temperature of N₂ was reduced from 4875 to 3099 K. Consequently, the average vibrational to rotational temperature ratio of N₂ was decreased from 4.96 to 2.48. By widening the capillary inner diameter from 100 to 200 μm, the average rotational temperature of N₂ was elevated from 891 to 1090 K whereas the average vibrational temperature of N₂ was dropped from 4662 to 3646 K and hence, the ratio of vibrational to rotational temperature of N₂ was lessened from 5.23 to 3.34. Moreover, with the addition of more nitrogen into the flow, i.e., by increasing the flow rate of N₂ from 0 to 15 sccm (with an interval of 5 sccm), the average rotational temperature of N₂ was intensified from about 942 to 1404 K, whereas the corresponding vibrational temperature of N₂ was reduced from 5011 to 3254 K. Therefore, the corresponding ratios of vibrational to rotational temperature of N₂ were declined from 5.3 to 2.3. The results demonstrate that the surface area to volume ratio of microplasma and gas conductivity have a significant effect on the non-equilibrium nature of He-N₂ atmospheric pressure microplasma.