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Atmospheric Pressure Plasma Treatment of Complex Interfaces [electronic resource].

University of Michigan. Nuclear Engineering & Radiological Sciences.

[S.l.] : University of Michigan. 2024 Ann Arbor : ProQuest Dissertations & Theses , 2024

1 online resource(226 p.)

Source: Dissertations Abstracts International, Volume: 86-03, Section: B.
Advisor: Kushner, Mark J.

Thesis (Ph.D.)--University of Michigan, 2024.

Technologies that use atmospheric pressure plasmas play a critical role in modern life and the economy. Advances in the field of atmospheric pressure plasmas help to invent and revolutionize these technologies. As new technology devices have become more complex and operated more selectively, research in the field of atmospheric pressure plasmas has concomitantly increased the complexity of the systems. One of the directions for increasing this complexity is surface morphology. Common laws and patterns of interaction of plasmas with surfaces, particularly those with complex interface configurations of different materials, have not been formulated. To approach this problem, a set of common standard surface types have been computationally studied for this dissertation using nonPDPSIM, a 2-D plasma hydrodynamics model.Through the application of surface dielectric barrier discharges to arrays of micropores in dielectrics that can represent catalyst supports or combustion filters, common patterns in uniformity of treatment are identified. The inhomogeneous treatment is identified to be caused by the electric field enhancement at a crest of non-planar regions of the interface. Further, principles of plasma propagation to pores with the extremely small opening of a few microns are determined to be guided by the photoionization source. Within a similar setup configuration, another interface, wet microchannels, is modeled. The formation of reverse ionization waves on the channels interface when being treated by the negative polarity pulse are first identified. When channels are extended in horizontal direction having as a result a higher surface-to-volume ratio, the treatment does not necessarily lead to more efficient coverage by fluxes due to non-uniform plasma propagation along such interface. The validation of the research on microchannels is continued with another setup in which microchannels are treated with an atmospheric pressure plasma jet. Modeling results of plasma propagation are compared with collaborative experimental research. The formation of reverse ionization waves on periodic microchannel structures is again observed, modeled, and explained. Extreme cases of rectangular microchannels that are extended in vertical directions up to several millimeters, which represent hair follicles on human skin, are modeled in contact with atmospheric pressure plasma. The propagation of plasma into the reservoir of hair-follicle-like structures is then demonstrated within the model and supported with a literature search. An atmospheric pressure plasma jet is also used in contact with another interface modeling abrupt change in the height of the surface, known as step barriers. The modeling and collaborative experimental research indicate the existence of a critical height above which plasma propagation is limited. Surface kinetics on a simplified polypropylene model is implemented on a step surface. The non-uniform formation of the resulting chemicals is demonstrated on the surface following the propagation and stopping of plasma with the sensitivity of the electric field at the apexes of steps.The aim of this dissertation is to contribute to the field of atmospheric pressure plasmas with a particular focus on interaction with solid and liquid interfaces of a complex morphology. Fundamental research in this field has an impact on the development of plasma sources that can be used in medicine, catalysis or microfluidic devices. Identifying shared principles governing plasma interaction with common interfaces like micropores, microchannels, microcapillaries, and step barriers can significantly advance the field's progress.

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