【作者】 李志；

【导师】 李学慧；

【作者基本信息】 大连理工大学 ， 等离子体物理， 2013， 博士

【摘要】 Ar/NH3混合气体放电在便携式氢气发生装置、保护环境、氮化硅薄膜沉积、磁性液体制备和纳米碳管改性等方面都有极其重要的应用。尽管存在关于Ar/NH3混合气体放电等离子体的部分实验和理论结果,但是由于成分复杂,粒子密度变化迅速等原因,测量等离子体参数需要复杂的实验设备。当前大气压等离子体放电的实验诊断手段仍旧十分有限。本项研究采用流体模型求解不同放电机制下Ar/NH3混合气体放电中的电子、离子和中性粒子的连续性方程,电子能量守恒方程和泊松方程,主要研究了等离子体参数对氨的主要中性产物和氨离子密度空间分布的影响。本论文的研究内容概括如下：第一章叙述了Ar/NH3混合气体放电的应用及理论和实验的研究进展,并阐述了本项研究的意义和主要内容。第二章采用一维流体模型对大气压直流平板电极Ar/NH3混合气体放电进行模拟,探讨了在该放电模式时,氨气浓度和压强对粒子密度的影响。模拟发现,最主要的离子是Ar2+和Ar+,Ar2+的密度比Ar+的密度约高一个数量级。发现NH2的密度随着压强的增加而增加的趋势比NH的密度随着压强的变化更明显。随着氨气浓度的增加和压强的增大,NH4+在氨离子中所占的比例变大,-而NH2-变化的趋势相反。NH+的密度比氨的其它正离子的密度低得多。并采用二维流体模型的结果与一维流体模型的结果进行比较。第三章采用一维流体模型对大气压同轴电极介质阻挡Ar/NH3混合气体放电进行模拟,探讨了氨气中间态粒子密度的空间分布和氨气浓度对粒子密度、气体温度和电子温度的影响。模拟发现,在该放电模式下,H2的密度大于H的密度。NH4+成为最主要的氨离子。氨气的浓度较低时,Ar2+离子的密度高于Ar+离子的密度。随着氨气浓度的增加,氨气分解产生大量的NH,H2和NH2分子,Ar2+离子与其反应被大量消耗,使得Ar+离子的密度高于Ar2+离子的密度。随着氨气浓度的增加,气体温度略升高,而电子温度则略降低。第四章采用二维轴对称的流体方程对低压微波电子回旋共振Ar/NH3混合气体放电进行模拟。探讨了压强和微波功率对粒子密度的影响。模拟发现,随着微波功率的增加,电子和氨离子的密度均增加,然而其空间分布的均匀性变差。在低压下,NH3+离子的密度依次高于NH2+, NH4+和NH+离子的密度。第五章采用二维混合模型模拟了氨气浓度对低压磁控直流平板电极设备中Ar/NH3混合气体放电的影响。模拟发现,在压强为5mTorr时,Ar+密度明显高于Ar2+密度,在氨离子中NH3+的密度最大,然后依次是NH2+, NH4+和NH+。当氩气和氨气的体积比为1：1时,主要带电粒子的密度减小,其空间分布的均匀性变好。电子温度略有增加。更多还原

【Abstract】 Ar/NH3admixture plasma discharge has an extremely important role in portable hydrogen generating device, environment protection, silicon nitride thin film deposition, magnetic fluid preparation and nanotube modification and so on. Although there were the partial experimental results and theoretical calculation results on Ar/NH3admixture plasma discharge, complex components and the densities significantly changed with time, and the complex equipments have been to measure the spatial and temporal parameters. The direct experimental diagnosis on the atmospheric pressure plasma discharge is still limited at present. The fluid model of the Ar/NH3admixture plasma discharges has been developed to solve the continuity equations for electron, ions and radials and the electron energy conservation equation and Poisson’s equation at the different discharge mechanism. The plasma parameters how to influence on the spatial distribution of the main radicals and ions of ammonia are studied by simulation.The research contents of the thesis are summarized as follows:In chapter one, the applications and the research progress of theory and experiment on argon and ammonia admixture discharge are described, and the significance and the main content of the research are introduced.In chapter two, the one-demonsional fluid model is adopted to simulate Ar/NH3admixture direct current discharge in planar electrode at atmospheric pressure. The ammonia concentration and the pressure how to effect on the particle density in the discharge mode are discussed. It found that the main ions are Ar2+and Ar+, the Ar2+density is about one order higher than the Ar+density.The density of NH2increases with pressure increased which is more obvious than that of NH. The proportion of NH4+density to that of ammonia ions becomes larger, while the NH2-density has an opposite trend when the ammonia concentration and pressure increased. And the density of NH+is significantly lower than that of the other positive ammonia ions. The results of two-dimensional fluid model are compared with those of one-dimensional fluid model.In chapter three, the one-demonsional fluid model is used to calculate an atmospheric pressure Ar/NH3admixture dielectric barrier discharge between the coaxial electrodes. The spatial distribution of the ammonia radials and the impact of ammonia concentration on the particle density, gas temperature and electron temperature are discussed respectively. It found that in the discharge mode the H2density is more than that of H. NH4+becomes the most important ammonia ion. The Ar2+ion density is higher than that of Ar+ion as ammonia concentration is low.Along with ammonia concentration increased, a large number of NH, H2and NH2are generated by the ammonia decomposition, and then Ar2+is consumed by reaction with them, it makes the Ar+ion density is higher than that of Ar2+ion. Along with ammonia concentration increased, gas temperature slightly increased, while electron temperature is slightly lower.In chapter four, the two-dimensional axisymmetric fluid model is used to simulate Ar/NH3admixture microwave electron cyclotron resonance discharge at low pressure. The impact of pressure and microwave power on the particle density is discussed. It found that the density of electron and the ammonium ions increased with the microwave power increased, while the uniformity of the spatial distribution is decreased. The NH3+density sequentially higher than that of the NH2+, NH4+and NH+ions at low pressure.In chapter five, the two-dimensional hybrid model is adopted to investigate ammonia concertion how to influence on the Ar/NH3admixture discharge in the magnetized direct current planar device at low pressure.lt found that the Ar+density is signficantly higher than the Ar2+density at5mTorr, and the most ammonia ion is NH3+, sequentially followed by NH2+, NH4+and NH+. The main charged particles density is lower, and the spatial distribution is slightly uniform, and the electron temperature is slightly increase as the volume ratio of argon and ammonia is1:1.更多还原