噴射式大氣電漿 (Atmospheric pressure plasma jet, APPJ) 因為無需使用昂貴的真空系統且具有多樣性的應用(例如表面處理或生醫應用等等)而在近年來備受重視。經過射頻功率的偶合後，其所產生的高電子溫度以及活性粒子密度也是受重視的原因之一。在本論文裡，我們首先整理了應用端的機制並發現原來氣體溫度以及高活性的氧物種都與應用上的成效有很大的關聯性。
我們進而研究頻率、氣體成分比例以及幾何結構對不同種類的噴射式大氣電漿及參數造成的影響。為了找出適當的研究方法，也研究了世界上不同研究團隊的模擬以及實驗結果。經過初步研究之後，我們認為射頻多電極氦/氧噴射式大氣電漿也許能夠只消耗相對低的功率且能達到功率或實務上廣泛的應用。
在本論文中，我們利用模擬以及實驗來觀察射頻多電極氦/氧噴射式大氣電漿的特性。在模擬上，ESI CFD-ACE+ 這套軟體被我們採用並為了數值分析發展出了二維流體模型。另一方面，在實驗上，我們不僅實際架設了上述所提的噴射式大氣電漿也同時佐以阻抗及光譜量測分析。
模擬結果首先展示了電子以及活性粒子密度的二維分布(隨時間以及到達穩態都有)，也展示了多電極噴射式大氣電漿在固定功率下的維持電壓。更進一步顯示了原子態的氧氣、亞穩態的氧氣(O2*)以及臭氧(O3)粒子為電漿在流出區域的主要活性粒子，也找出了亞穩態的氧氣(O2*)以及臭氧(O3)粒子在電漿中生成的主要反應式。而經由模擬上的參數最佳化，我們發現經由條件為功率1.5 W、流速3 m/s以及混了0.3%的氧氣所點起的大氣電漿可能同時具有僅消耗低功率且產生高濃度的活性粒子的特性。另一方面，在實驗上，我們實際點了電漿且利用照片展示電漿分布，也從阻抗及光譜量測分別得到了氦/氧放電的電流-電壓曲線以及光譜。光譜的結果可使我們了解電漿內的活性物種。也由兩條波長差較多的惰性氣體特徵譜線之比值，得到電子溫度隨著電壓是有上升的趨勢。
因此對於未來目標，在短期內，我們要在模擬上考慮電漿在開放空間的情形，因為從實驗得來的光譜可以得知活性氮物種對於電漿的維持也很重要，進以得到能夠操作在廣範圍的噴射式大氣電漿，而長遠目標則是希望能在實務上先應用在表面處理以測試其成效，並利用水接觸角估計電漿所產生的活性氧物種的分布及多寡。

Atmospheric pressure plasma jets (APPJs) have attracted a great deal of attention recently since they do not need expensive vacuum system, enabling a wide variety of application such as surface modification or bio-medical treatments, etc. As can be seen, APPJs produce non-thermal plasmas where extremely high electron temperature (1~2 eV) and active plasma species are generated when radio-frequency powers are applied. In this thesis, we summarized the mechanisms of applications and found that the gas temperature and the reactive oxygen species (ROS) generated in plasma plume are strongly related with the effect of applications.
Then, we investigated various types of APPJs and their parameters including effects of frequencies, gas compositions and configurations. Also, we studied simulation and experiment results of world-wide groups in order to take their research methods as references. After the investigations, we realized that to low the power consumption and temperature for APPJs, a Multi-electrode dielectric barrier helium/oxygen discharge coupled with radio-frequency power might be able to achieve low power consumption (low gas temperature) and wide range operation.
In this thesis, we investigate the characteristics of radio frequency multi-electrode Helium/Oxygen atmospheric pressure plasma jets (RF ME He/O2 APPJs) by simulation and experiment. For simulation, a two-dimensional (2-D) fluid model for numerical analysis using ESI CFD-ACE+ was developed. For experiment, on the other hand, an experimental configuration was set up with impedance and optical emission spectroscopic (OES) measurements.
Simulation results represents the 2-D distributions of electron density and reactive species vary with times and reach to the steady states. The results also show the sustain voltage in typical case for ME APPJ. Also, they point out that the atomic oxygen (O), metastable oxygen (O2*) and ozone (O3) are main reactive oxygen species (ROS) generated by plasma and the main reactions for ROS formations. After doing the parameter optimization, we found out ME APPJ ignited with 1.5 W, 3 m/s and 0.3% O2 mixed might be achieve low power consumption and high ROS generation according to the simulation results. For experimental results, we show the photograph of ignited plasma plume in order to demonstrate the distribution of plasma. Also, with impedance and OES measurement, I-V curve and optical spectra of helium/oxygen discharge are presented. From the spectra, the reactive species in discharge are investigated. Moreover, the emission ratios of noble gas transitions that quite apart in wavelength at different voltage are presented. We found out an increasing trend as voltage rising up.
Therefore, for future works, the short term is to carry out the effects of gas composition in open air since the spectra shows that reactive nitrogen species (RNS) are also important for discharge. Once the analyses are done, the experimental structure will be adopt for applications as well. For the long term, we will do surface treatment for glass substrate and heat-sensitive materials. Water contact angle measurement will also be considered to estimate the densities and distributions of reactive oxygen species generated by plasma plume.

摘要 i
Abstract iii
Acknowledgements v
Content 1
Lists of Tables 3
Lists of Figures 4
Chapter 1 9
Introduction 9
§ 1.1 Atmospheric Pressure Plasma Jets (APPJs) 10
§ 1.2 Thermal and Non-thermal Equilibrium Plasmas 12
§ 1.3 Applications of APPJs 14
§ 1.4 Reactive Species Induced in APPJs 17
Chapter 2 21
Literature Review 21
§ 2.1 Gas Compositions of APPJs 22
§ 2.2 Radio Frequency Powers of APPJs 26
§ 2.3 Configurations of APPJs 27
§ 2.4 Simulation Investigations 29
§ 2.5 Experiment Investigations 34
§ 2.6 Research Motivation 39
Chapter 3 40
Methods – Simulation 40
§ 3.1 Finite Volume Method (FVM) and Calculating Procedure 40
§ 3.2 Capacitive Coupled Plasma Model (CCP Model) 43
§ 3.3 Boundary Condition 47
Methods – Experiment 48
§ 3.4 Experimental set up 48
§ 3.5 Optical Emission Spectroscopy (OES) 49
Chapter 4 51
Results – Simulation 51
§ 4.1 Description of Simulation Model 51
§ 4.2 Simulation Parameters and Gas Phase Reactions 53
§ 4.3 Basic Characteristics of ME He/O2 APPJ Discharge 61
Time-dependent (Transient) Results 63
Steady State Results 66
Results – Experiment 83
§ 4.4 Experimental results 83
§ 4.5 Plasma Diagnostics 84
Chapter 5 87
Summary and Future Works 87
Reference 89

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