【作者】 李宏；

【导师】 李寿哲；

【作者基本信息】 大连理工大学 ， 等离子体物理， 2013， 硕士

【摘要】 大气压等离子体不需要昂贵的真空设备的辅助,能够有效地降低设备投资和维护以及生产成本,并可以实现连续性生产。因此,近年来其在实际的应用中得到了广泛的关注。本文通过射频容性耦合放电的方式,在工作气体注入端采用预激发的技术手段在平板型裸露金属电极中产生了均匀稳定的氩/氮射频辉光放电,得到了具有高浓度活性粒子的低温氩/氮等离子体。我们首先从放电形态上揭示了氩/氮射频辉光放电等离子体的三种不同放电模式,即正常辉光α放电模式,反常辉光α放电模式和γ/arc放电模式。给出了不同N2/Ar气体混合比例下,射频辉光放电刚进入到反常辉光α放电模式和γ/弧放电模式时的临界电压和电流值。并分析了α放电模式下氩/氮等离子体的电流电压特性(CVC)曲线随氮气含量的变化规律。由于气体放电的电学特性是诊断等离子体的重要依据,我们分别测量了氩/氮射频辉光放电等离子体的阻抗,相位角,电阻和电抗随氮气含量的变化关系。其次,发射光谱法作为诊断等离子体的重要手段,我们利用氮分子的第二正带发射谱线给出了氮分子C态上粒子数的振动态分布函数(VDF)及归一化分布特性(NDC)曲线,实验结果表明：氮分子C态上粒子数的振动分布函数满足玻尔兹曼分布,并计算了氮分子的振动温度约为2216K。另外,利用光化线强度法测定了氮原子的相对浓度随着氮气含量的变化趋势,发现氮原子浓度一致地随氮气含量的增加而上升。最后,对氩/氮等离子体在玻璃表面亲水性改良上的应用进行了初步的研究,并给出了定性的解释。另外,我们对微等离子体射频容性耦合放电的网络匹配中传输线对匹配的影响做了深入和系统的探讨。在微等离子体射流阻抗匹配的实验中,通过改变连接匹配箱和放电装置之间同轴线的长度和信号源调谐频率大小实现了为射频容性耦合的介质阻挡微等离子体源提供了足够高的谐振电压用以激励和维持等离子体放电的目的。首先,利用阻抗分析仪测量了同轴线的阻抗特性,确立了电容值随长度的变化关系；其次,通过改变信号发生器频率,确立了回路的谐振频率值和同轴传输线长度的依赖关系；最后,发现了在微等离子体源反应器上获得的谐振电压随同轴线长度的变化规律。并从电路原理上通过建立等效电路模型对实验结果进行了分析,给出了满意的解释。实验结果表明：在我们所考察的电源频率范围内同轴传输线呈现容性,并且随着同轴线长度的增加,其电容值线性增加；回路谐振频率和微等离子体源两端电压随着同轴线长度呈递减关系。更多还原

【Abstract】 Atmospheric-pressure plasma can effectively reduce equipment investment, maintenance and production costs, and can realize continuous production by elimination of the need for an expensive vacuum system. Therefore, there is a widespread concern for its applications in recent years. In this paper, a uniform and stable atmospheric-pressure radio-frequency Ar/N2glow discharge was produced in a parallel bare metal plate reactor by means of radio-frequency capacitively coupled discharge through pre-excitation technique at the inlet of the working gas.First, three different discharge modes of Ar/N2glow discharge were revealed from the discharge forms:normal a-mode glow discharge mode, abnormal a-mode glow discharge and y-mode/arc discharge, respectively. The variation of the critical voltage and current values versus the nitrogen-to-argon ratios was given while the Ar/N2radio-frequency plasma translated into abnormal a mode and y mode/arc discharge. The variation of current-voltage characteristic (CVC) curves for the Ar/N2plasma versus nitrogen percentages was analyzed, also. Since the electrical characteristic of a gas discharge is an important basis for diagnosis of plasma, the impedance, phase angle, resistance and reactance of the Ar/N2glow discharge plasma versus the nitrogen-to-argon ratios was measured, respectively. The experiment results showed that the critical voltage values increased monotonously with increasing addition of nitrogen, while the critical current values changed slightly; it was found that each of the current-voltage curves consists of two segments which corresponds to a normal a-mode discharge and an abnormal a-mode discharge, each varying almost linearly at different slopes with respect to two segments. Second, When optical emission spectroscopy (OES) is used as an important means of diagnosis of plasma, the vibrational distribution function (VDF) of the nitrogen molecules (C3Πu, u’=0-3) state and the normalized distribution characteristic (NDC) curves was analyzed using the second positive band of N2spectrum. The experiment results showed that the VDF is closed to Boltzmann distribution, and the vibrational temperature varied slightly, which can be estimated to be about2216K with respect to the uncertainty of5%. Additionally, the relative variation of the N-atom density with the nitrogen-to-argon ratios was obtained actinometrically. It was founded that the N-atom density increased coincidently with addition of nitrogen. Last, the hydrophilic modification of slide glass treated by Ar/N2plasma was studied experimentally, and a qualitative explanation was given.Furthermore, the matching issue of radio-frequency capacitively coupled microplasma discharge has been investigated with respect to the influence of transmission line. It is by changing the frequency of signal source and the length of coaxial lines between the matching box and the plasma reactor that a high resonance voltage was generated and supplied for an atmospheric-pressure capacitively coupled dielectric-barrier plasma source to strike and maintain plasma discharge at atmospheric pressure. First, in order to obtain the variation tendency of capacitances of coaxial lines versus their length, the impedance characteristics of coaxial lines was measured by using RF impedance analyzer; Second, the variation tendency of circuit resonance frequency versus the length of coaxial lines was determined by changing the frequency of the signal generator; Finally, the variation tendency of the resonance voltage in the terminal plasma reactor versus the length of coaxial lines was obtained. Also, the experiment results were analyzed by means of circuitous philosophy with introduction of an equivalent circuit, which gives a satisfactory agreement. The experiment results showed that coaxial transmission lines exhibited capacitances in the working frequency range and their capacitances increased linearly with the length of the transmission line; the circuit resonance frequency and the terminal reactor voltage decreased with the length of coaxial transmission line.更多还原