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Characterization of Dust-Plasma Interactions In Non-Thermal Plasmas Under Low Pressure and the Atmospheric Pressure.

机译：低压和大气压下非热等离子体中粉尘-等离子体相互作用的表征。

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This dissertation research focuses on the experimental characterization of dust-plasma interactions at both low and atmospheric pressure. Its goal is to fill the knowledge gaps in (1) the fundamental research of low pressure dusty plasma electrons, which mainly relied on models with few experimental results; and (2) the nanoparticle synthesis process in atmospheric pressure uniform glow plasmas (APGDs), which is largely unexplored in spite of the economical advantage of APGDs in nanotechnology.;The low pressure part of the dissertation research involves the development of a complete diagnostic process for an argon-siline capacitively-coupled RF plasma. The central part of the diagnostic process is the Langmuir probe measurement of the electron energy probability function (EEPF) in a dusty plasma, which has never been measured before. This is because the dust particles in the plasma cause severe probe surface contamination and consequently distort the measurement. This problem is solved by adding a solenoid-actuated shield structure to the Langmuir probe, which physically protects the Langmuir probe from the dust particle deposition to ensure reliable EEPF measurements. The dusty plasma EEPFs are characterized by lower electron density and higher electron temperature accompanied by a drop in the low energy electron population. The Langmuir probe measurement is complemented with other characterizations including the capacitive probe measurement, power measurement, and dust particle collection. The complete diagnostic process then gives a set of local plasma parameters as well as the details of the dust-electron interactions reflected in the EEPFs. This set of data serves as input for an analytical model of nanoparticle charging to yield the time evolution of nanoparticle size and charge in the dusty plasma.;The atmospheric pressure part of the dissertation focuses on the design and development of an APGD for zinc oxide nanocrystal synthesis. One of the main difficulties in maintaining an APGD is ensuring its uniformity over large discharge volume. By examining past atmospheric pressure plasma reactor designs and looking into the details of the atmospheric pressure gas breakdown mechanism, three design features are proposed to ensure the APGD uniformity. These include the use of a dielectric barrier and the RF driving frequency, as well as a pre-ionization technique achieved by having a non-uniform gap spacing in a capacitively-coupled concentric cylinder reactor. The resulting APGD reactor operates stably in the abnormal glow regime using either helium or argon as the carrier gas. Diethylzinc (DEZ) and oxygen precursors are injected into the APGD to form zinc oxide nanocrystals. The physical and optical properties of these nanocrystals are characterized, and the system parameters that impact the nanoparticle size and deposition rate are identified.
机译：本论文的研究重点是在低压和大气压力下粉尘-等离子体相互作用的实验表征。其目的是填补（1）低压尘土等离子体电子的基础研究的知识空白，该研究主要依靠很少有实验结果的模型； （2）大气压均匀辉光等离子体（APGDs）中的纳米粒子合成过程，尽管APGDs在纳米技术上具有经济优势，但在很大程度上尚待探索。;论文的低压部分涉及开发完整的诊断过程。用于氩-氩电容耦合的射频等离子体。诊断过程的中心部分是在尘土飞扬的等离子体中对电子能量概率函数（EEPF）进行Langmuir探针测量，这是以前从未测量过的。这是因为等离子体中的灰尘颗粒会导致严重的探头表面污染，从而使测量变形。通过向Langmuir探头添加螺线管致动的屏蔽结构可以解决此问题，该结构可物理保护Langmuir探头免受灰尘颗粒的沉积，从而确保可靠的EEPF测量。尘土等离子体EEPF的特征在于较低的电子密度和较高的电子温度，同时伴随着低能电子群体的下降。 Langmuir探头测量与其他特性相辅相成，包括电容探头测量，功率测量和灰尘颗粒收集。然后，完整的诊断过程将提供一组局部血浆参数以及EEPF中反映的粉尘-电子相互作用的详细信息。这组数据可作为纳米颗粒带电分析模型的输入，以产生纳米颗粒尺寸和尘埃等离子体中带电的时间演化。论文的大气压部分着重于氧化锌纳米晶体APGD的设计和开发合成。维持APGD的主要困难之一是确保其在大排量下的均匀性。通过检查过去的大气压等离子体反应器设计并研究大气压气体分解机理的细节，提出了三个设计特征以确保APGD的均匀性。这些措施包括使用电介质势垒和RF驱动频率，以及通过在电容耦合的同心圆柱电抗器中具有不均匀的间隙间距而实现的预电离技术。使用氦气或氩气作为载气，所得的APGD反应器在异常辉光状态下稳定运行。将二乙基锌（DEZ）和氧气前驱物注入APGD中以形成氧化锌纳米晶体。表征了这些纳米晶体的物理和光学性质，并确定了影响纳米颗粒尺寸和沉积速率的系统参数。

著录项

  • 作者

    Bilik, Narula.;

  • 作者单位

    University of Minnesota.;

  • 授予单位 University of Minnesota.;
  • 学科 Physics.;Nanotechnology.
  • 学位 Ph.D.
  • 年度 2016
  • 页码 116 p.
  • 总页数 116
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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