氮氣大氣電漿噴流特性探討

Abstract

本研究探討氮氣大氣電漿噴流特性，藉由建立包含流體力學、熱傳輸、粒子擴散的多物理耦合數值模型，計算並討論其流場、溫度、粒子分佈等特性，並透過工作平台上的量測實驗設計做比對驗證。再藉由改變實驗參數及基材材料，分析系統受影響後各特性的變化。 研究使用含石英管的氮氣大氣電漿系統，藉由數值模型可以觀察到石英管內的流場會形成兩個渦旋，隨著流場往下游溫度及氮氣激態粒子逐漸降低，氧氣及氮氧化物則是沿著下游逐漸增加。而在工作平板上的溫度分佈，數值模型及實驗量測上有很好的吻合。 改變實驗參數的模擬結果顯示，參數的調整會表現在大氣電漿噴流的不同特性上。在大氣電漿氮氣源摻雜氧氣雜質增加時，由於氧氣增加的影響，會造成大氣電漿噴流的氮氣激態粒子減少，氧原子、臭氧及氮氧化物增加。增加氣體流量則會使得大氣電漿噴流的溫度明顯降低，氮氣激態粒子增加，影響其他粒子分佈及濃度。加大石英管下方至工作平台間隙高度則會增加下游溢入的空氣量，使得下游溫度降低且氮氣激態粒子減少、氮氧化物增加。在康寧玻璃、藍寶石晶圓及碳布三種基材進行數值模擬及溫度量測實驗的結果亦有良好對照。 利用數值模型的建立，可以對於氮氣大氣電漿噴流有特性上的了解，並提供實驗應用上調整參數的參考依據。例如輸入氣體在濃度差異及流量調整上都會影響電漿輸出的不同特性，也可以藉由控制石英管下方的間隙高度增減氣體的混合效率，進而達到改變基態粒子濃度的調整。

This research presents analyses of the nitrogen atmospheric pressure plasma jet (APPJ). Multi-physics numerical models with fluid dynamics, heat transfer, and species transfer were developed to simulate the fluid field, temperature, and species distribution of APPJ. Furthermore, experiments of temperature measurement were set up to verify the temperature characteristics on the working platform. Then, the influences of different inlet gas impurity, flow rate, the gap between the quartz tube and the working plate, and the type of the substrate were discussed. Based on the numerical model, the flow of APPJ would form two vortices in the quartz tube. The temperature and nitrogen excited state species decreased along the stream, while oxygen and NOx-related species increased. In addition, the temperature profile on the working plate were validated by experimental measurement data. The numerical results showed that the adjustment of experimental parameters would contribute to APPJ characteristics. When adding oxygen impurity, the nitrogen excited state species decreased, and oxygen and NOx-related species increased. With a larger flow rate, the temperature of APPJ obviously decreased, nitrogen excited state species increased, and other species distribution were also varied. While enlarging the gap between quartz tube and the working plate, the temperature and nitrogen excited state species decreased and NOx-related species increased downstream because of more air mixture. Moreover, the temperature distribution on different substrates of Corning EXG glass, sapphire wafer, and Carbon cloth were also in accordance with experimental data. In summary, with the assistance of the numerical model, the characteristics of APPJ could be specified, and this study could be a reference for experimental adjustment for APPJ application. For example, the APPJ output characteristic could be influenced by the inlet gas impurity and flow rate, and one can adjust the excited species concentration by controlling the gap under the quartz cylinder to vary the gas mixture efficiency.