Pulsed Corona Discharge in Supercritical Carbon Dioxide: Fundamentals and Applications

公共摘要CTS-0522578，PI：Lawrence A.肯尼迪，伊利诺伊大学芝加哥分校脉冲电晕放电在超临界二氧化碳：基础知识和应用的非热等离子体的应用范围从材料处理到污染控制。 在努力增加激发态或反应物的密度，或处理非气态介质，非热放电的缩放到高压，液体和多相系统是非常感兴趣的。 超临界流体（SCFs）是一类特殊的高密度流体，由于其独特的清洁和溶剂化性能，已在其自身的程序中进行了研究。SCF具有介于气体和液体状态之间的密度和传输性质，具有固有的空间不均匀性，并且通常被称为"簇"流体。本计画探讨SCF电浆与放电之几乎未被探索但实际上重要的领域。 预计SCF中维持的等离子体具有独特的化学反应性，这是由于SCF的固有团簇流体性质以及通过等离子体中的电子撞击过程产生的自由基和离子。 即使是SCF等离子体的最基本的特性在很大程度上是未知的，因此我们利用其独特特性的能力受到严重阻碍。 该项目的目标是研究和表征放电的启动和SCF等离子体中的传播。 在超临界CO2放电引发的实验研究正在进行在超临界压力和温度的范围很广。 流光击穿机制正在研究中，包括临界电场，传播速度，直径，分支，和火花过渡。 重点放在空间不均匀性的作用，从固有的纳米级集群等离子体特性。 诊断包括空间和时间分辨ICCD成像，光谱学和纹影技术。一个全面的数据库放电和流光参数SCF包括击穿电压，流光速度，SCF等离子体的空间特性开始组装。 更广泛的影响涉及科学、技术和教育的进步。 这项研究提供了基本的新的见解流光在非均匀介质中的传播，包括各种大小和结构的集群。 因此，这项工作为其他人利用这种新的SCF等离子体提供了一个基线，这将补充高压气体和液体放电的研究。 这项研究也推进了尘埃等离子体和微等离子体相关领域的知识。 从实用的角度来看，这项研究打开了非热超临界等离子体领域的技术优势。 利用SCF等离子体的特性将可能扩展和改进现在利用传统SCF的技术。 独立地，非平衡等离子体和SCF已被证明是氧化，蚀刻部件，污染去除，材料合成，传感器，细菌灭活和聚合的特殊工艺。 这两个进程的结合有可能产生重大的协同增效作用。研究和教育通过服务于几个重要群体的机制进行整合，包括：研究生和本科生以及研究人员，开辟了等离子体科学和工程的新领域。 本科生通过本科研究的学术学分参与该项目的许多方面。

Public AbstractCTS-0522578, PI: Lawrence A. Kennedy, University of Illinois ChicagoPulsed Corona Discharge in Supercritical Carbon Dioxide: Fundamentals and Applications Applications of non-thermal plasmas range from material processing to pollution control. In an effort to increase the density of excited states or reactants, or to process non-gaseous media, the scaling of non-thermal discharges to high pressures, liquids, and multiphase systems is of great interest. Supercritical fluids (SCFs) are a special class of high-density fluids that have been investigated in their own rite due to their unique cleaning and solvating properties. Having densities and transport properties intermediate between the gas and liquid states, SCFs have inherent spatial inhomogeneities and are often referred to as "cluster" fluids. This project investigates the nearly unexplored but practically important area of SCF plasmas and discharges. Plasmas sustained in SCFs are expected to have unique chemical reactivity resulting from both the inherent cluster-fluid properties of SCFs; and radical and ion production through electron impact processes in plasma. Even the most fundamental properties of SCF plasmas are largely uncharacterized; so our ability to leverage their unique properties is severely hindered. The project goal is to investigate and characterize discharge initiation and propagation in SCF plasmas. Experimental investigations on electric discharge initiation in supercritical CO2 are being performed over a wide range of supercritical pressures and temperatures. The streamer breakdown mechanism is being investigated including critical electric field, propagation velocity, diameter, branching, and spark transition. Emphasis is placed on the role of spatial inhomogeneities resulting from the inherent nanoscale clustering on plasma properties. Diagnostics include spatially and temporally resolved ICCD imaging, optical spectroscopy, and Schlieren techniques. A comprehensive database on discharge and streamer parameters in SCFs including breakdown voltages, streamer velocities, and spatial characteristics for SCF plasmas is beginning to be assembled. The broader impact involves advances in science, technology, and education. This study is providing fundamental new insights on streamer propagation in inhomogeneous media incorporating clusters of various size and structure. As such, the work is providing a baseline for others to exploit this new class of SCF plasma, which will compliment research on discharges in high-pressure gases and liquids. The research is also advancing knowledge in related areas of dusty plasmas and microplasmas. From a practical perspective, this research opens the area of non-thermal supercritical plasmas for technological benefit. Exploiting the properties of SCF plasmas will likely extend and improve the technologies that now utilize conventional SCFs. Independently, both non-equilibrium plasmas and SCFs have proven to be exceptional processes for oxidizing, etching parts, pollution removal, material synthesis, sensors, bacteria inactivation and polymerization. The combination of both processes holds the promise of significant synergistic enhancements. Research and education are integrated via mechanisms that will serve several important constituencies, including: graduate and undergraduate students and fellow researchers through opening up a new area of plasma science and engineering. Undergraduate students are involved in many aspects of this project through academic credit for undergraduate research.