Browsing by Author "Go, David B."

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    Noncapillary Wave Dynamics due to Interfacial Coupling with Plasma Patterns at a Liquid Surface
    (American Physical Society, 2024) Dubrovski, Oles; Yang, Jinyu; Veloso Espinosa, Felipe Eduardo; Go, David B.; Chang, Hsueh-Chia; Rumbach, Paul
    We identify a new class of surface waves that arise at a plasma-liquid interface due to resonant coupling between discrete plasma pattern modes and a continuum of interfacial liquid surface wave modes. A wave mode is selected due to localized excitation by the plasma, and standing waves result when waves excited from different locations interact. These waves propagate with a slower phase velocity than traditional capillary waves, but exhibit the same damping behavior with respect to liquid viscosity. Surface tension does not appear to play a significant role. We propose a curvature-dependent Maxwell pressure mechanism to explain these nondispersive interfacial waves in the presence of plasma.
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    Temperature Inhibition of Plasma-Driven Methane Conversion in DBD Systems
    (2023) Akintola, Ibukunoluwa; Rivera-Castro, Gerardo; Yang, Jinyu; Secrist, Jeffrey; Hicks, Jason C.; Veloso, Felipe; Go, David B.
    Low-temperature non-thermal plasmas produce highly reactive chemical environments made up of electrons, ions, radicals, and vibrationally excited molecules. These reactive species, when combined with catalysts, can help drive thermodynamically unfavorable chemical reactions at low temperatures and atmospheric pressure. The conversion of methane (CH4) to produce other value-added chemicals is a good model system because of its applicability to a wide range of industries. To effectively create these plasma catalytic systems, a fundamental understanding of the plasma-phase chemistry alone is imperative. While there have been many studies on methane plasmas and how certain operating conditions (i.e., gas composition and power) affect the plasma, there is limited understanding on how changing bulk reaction temperature affects the plasma properties and ensuing plasma chemistry. In this work, we use a dielectric barrier discharge to investigate the effects of temperature on the reaction chemistry and the plasma's electrical properties in various methane-gas mixtures. Results show that increasing temperature leads to a reduction in methane conversion as well as changes to both the gas and dielectric material pre-breakdown, which manifests itself in temperature-dependent electrical properties of the plasma. Experiments at various temperatures and power show a positive correlation between key electrical plasma properties (average charge and lifetime per filament) and the measured methane conversion as a function of temperature.