Micro-Plasmas Through Porous Media

多孔介质可以被认为是对流体流（例如气体或液体）基本上透明的材料。 这种材料的内表面积很大，使得该材料非常适合化学加工应用。多孔介质在现代社会中发挥着重要作用，其应用范围从水过滤（如活性炭过滤器）到空气过滤。实际上，催化转化器利用多孔介质的高表面积与体积比来实现汽车废气的高减排效率。 多孔介质的新兴应用包括燃料电池和清洁燃烧。 多孔介质燃烧特别地发生在孔隙中。在那里释放的能量提高了介质温度，因此喷射的燃料在进入时自动点燃。这项技术有可能减少汽车排放，并通过实现非常稀薄的燃料燃烧来显着提高燃油效率。 在孔内引入少量的电离气体（微等离子体）可以进一步降低点火温度，从而允许进一步提高效率。此外，在孔隙中产生的反应性微等离子体具有分解有毒燃烧副产物以及清洁孔隙以大大提高使用寿命的潜力。 目前，多孔介质中微等离子体的产生还没有得到很好的理解。 这项工作的目的是提高理解和优化生产的微等离子体在多孔介质中使用的实验和模拟相结合。 这项工作的目标是弥合多孔介质中等离子体产生的科学理解与实际应用之间的差距。从这一努力中获得的理解有助于开发和实现清洁燃烧、高效、低排放的汽车、先进的燃料电池和先进的工业烟囱洗涤器。 一个基本的物理条件，导致互连等离子体从孔到孔的传播的理解是必要的，才可以合理地控制，从而利用多孔介质中的微等离子体（MPPM）。 我们预计，孔隙和等离子体雪崩的孔隙内，表面充电和辐射传输增强之间的扩散运输的组合，在建立相邻的孔隙之间的等离子体互连发挥关键作用。 然而，现在几乎没有实验或理论证实这些或其他理论。 在本研究计画中，我们将探讨在化学反应环境中，大气压电浆在多孔介质中传播的基本特性。 我们的目标是提高我们对等离子体表面相互作用的理解，这导致MPPM，通过综合实验测量和第一原理，流体，混合动力学建模相结合的合作调查。 将研究两种配置。 第一种是由填充床反应器表示的结构化多孔材料，该填充床反应器由具有受控半径、介电常数、电导率和布置的电介质珠或棒组成，该电介质珠或棒放置在金属电极之间。 第二种结构将是真正随机结构的多孔材料，陶瓷和/或金属泡沫，如市售的。 该项目还包括针对低收入学生的K-12外联工作。这项工作的目的是向学生介绍等离子体科学和等离子体辅助燃烧的新兴领域，通过实验和科学课程模块的手。

Porous media may be thought of as material that is essentially transparent to fluid flow (e.g. gas or liquid). The internal surface area of such materials is substantial, making the material excellent for chemical processing applications. Porous media play an important role in modern society with applications ranging from water filtration, such as activated charcoal filters, to air filtration. Indeed, a catalytic converter exploits porous media's high surface area to volume ratio to achieve high emission reduction efficiency in automobile exhausts. New and emerging applications of porous media include fuel cells and clean combustion. Porous media combustion in particular takes place in the pores. The energy released there elevates the medium temperature so that injected fuel automatically ignites upon entry. This technology has the potential to reduce auto emissions and significantly increase fuel efficiency by enabling very lean fuel burns. The introduction of small amounts of ionized gas, a micro-plasma, inside the pores can further reduce ignition temperature thereby allowing for further increases in efficiency. Additionally, reactive micro-plasmas produced in the pores have the potential to decompose toxic combustion byproducts as well as to clean the pores to greatly improve service lifetime. Currently, the micro-plasma production in porous media is not well understood. This effort aims to improve the understanding and optimize the production of micro-plasmas in porous media by using a combination of experiments and simulations. The goal of the effort is to bridge the gap between scientific understanding of plasma production in porous media and actual applications. The understanding obtained from this effort contributes to the development and realization of clean burning, highly efficient, low emission automobiles, advanced fuel cells and advanced industrial smoke stack scrubbers. A fundamental understanding of the physical conditions that lead to interconnected plasma propagation from pore to pore is necessary before one can credibly control and thus exploit micro-plasmas in porous media (MPPM). We expect that a combination of diffusive transport between pores and plasma avalanche within the pores, augmented by surface charging and radiation transport, play key roles in establishing plasma interconnectivity between adjacent pores. However there is now little experimental or theoretical confirmation of these or other theories. In this research project, we will investigate the basic properties of atmospheric pressure plasmas propagating into and through porous media in chemically reacting environments. The goals are to improve our understanding of plasma-surface interactions, which lead to MPPM, through a collaborative investigation combining comprehensive experimental measurements and first-principles, fluid, hybrid and kinetic modeling. Two configurations will be studied. The first is a structured porous material represented by a pack-bed reactor consisting of dielectric beads or rods having a controlled radius, permittivity, conductivity and layout placed between metal electrodes. The second configuration will be a truly randomly structured porous material, ceramic and/or metal foam, as is commercially available. The project also includes a K-12 outreach effort targeting low-income students. The effort aims to introduce the students to plasma science and the emerging field of plasma-aided combustion through both hands on experiments and science lesson modules.