Bulletin of the American Physical Society
73rd Annual Gaseous Electronics Virtual Conference
Volume 65, Number 10
Monday–Friday, October 5–9, 2020; Time Zone: Central Daylight Time, USA.
Session YF3: Plasma-liquid Interaction IILive
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Chair: Mohammad Hasan, University of Liverpool |
Friday, October 9, 2020 1:00PM - 1:15PM Live |
YF3.00001: Modeling Humid Helium Plasmas and Their Interaction with Liquid Water Droplets Mackenzie Meyer, Gaurav Nayak, Peter Bruggeman, Mark J. Kushner Atmospheric pressure plasma activation of liquid water droplets is typically more efficient at transferring reactive species to the liquid than treating bulk liquid due to the droplets' larger surface-to-volume ratio. The mechanisms for transferring plasma activated species into a droplet are not clear, particularly for short-lived species that may also react in the evaporating layers adjacent to the surface of the droplet. To quantify these processes, single droplets in atmospheric pressure radio frequency excited He discharges are being investigated experimentally and computationally. The droplets contain formate, and the change in formate concentration is a measure of interactions between short-lived species such as OH$_{\mathrm{aq}}$ and the droplet. The 2D modeling platform \textit{nonPDPSIM} was used to simulate a reduced volume near the droplet and the full reactor with and without the water droplet to ascertain the influence of the droplet on the plasma. The plasma is sustained in humid He between electrodes 9.5 mm long and separated by 2 mm. 40 micron diameter water droplets flow with the ambient gas through the plasma. Plasma properties near the droplet, transfer of plasma activated species to the droplet and formate consumption will be discussed, with comparison to companion experiments. [Preview Abstract] |
Friday, October 9, 2020 1:15PM - 1:30PM Live |
YF3.00002: Spatial Distribution of Reduction Potential near the Plasma-Liquid Interface Trey Oldham, Elijah Thimsen Systems comprised of aqueous media in contact with nonthermal atmospheric pressure plasma jets (APPJs) have attracted interest for biomedical, agricultural, and nanomaterial synthesis applications. The emerging field of plasma electrochemistry uses atmospheric pressure plasma, generated using noble gases, as a means to drive redox reactions. Free electrons from the noble gas plasma become solvated in solution, creating a chemically reducing environment. Many important fundamental questions about the plasma-liquid interface remain unanswered. For example, if a reduction reaction occurs in the liquid beneath the plasma jet, where does the complementary oxidation half-reaction occur that is required to maintain charge neutrality in the solution? In this work, the spatial distribution of the reduction potential for a solution in contact with a radiofrequency APPJ is presented. Treating the plasma-liquid interface as a boundary condition that constrains the reduction potential, a parametric study will be presented relating process parameters to the spatial distribution of the reduction potential. More specifically, the influence of applied power, gas flow rate, and jet standoff distance on the location and magnitude of the reducing and oxidizing zones in the liquid will be presented. The knowledge of how process parameters affect the spatial distribution of reduction potential in solution can be used to design electrodeless electrochemical reactions using the plasma-liquid interface. [Preview Abstract] |
Friday, October 9, 2020 1:30PM - 1:45PM Live |
YF3.00003: Gas-liquid Interfacial Plasma Using High-speed Liquid Flow for Analyzing Short-lived Reactive Species Transport Toshiro Kaneko, Kazuki Takeda, Keisuke Takashima, Shota Sasaki Atmospheric-pressure plasmas (APPs) have recently emerged as a novel technology for life science (medical and agricultural) applications. Although APP-produced short-lived reactive species in the liquid phase could be key factors in their applications, the analysis of the short-lived reactive species transport is still challenging due to their high reactivity and coexisting various species. In order to analyze decay of OH radical (one of important short-lived reactive species) in APP-exposed water, we developed a He-APP device with high-speed (\textasciitilde 10 m/s) liquid flow. This system gives a high temporal resolution measurement of OH radical in the liquid phase. We have experimentally measured APP-produced OH radical decay and showed a space-time distribution of OH radical based on a reaction-diffusion model which is consistent with the experimentally obtained OH radical decay. [Preview Abstract] |
Friday, October 9, 2020 1:45PM - 2:00PM Live |
YF3.00004: Modeling solvated electron penetration depth and aqueous chemistry at the humid air plasma-water interface Shane Keniley, Davide Curreli Plasma-liquid systems are experiencing growing interest due to their applications in medicine and chemical production. In this work the interface of a humid air plasma impacting a water surface is modeled in the MOOSE-based open source finite element model, Zapdos-Crane. Electrons are allowed to directly penetrate the water interface through advection, and heavy species transport between gas and liquid phases is included through Henry's law. The effect on varying electron current density and oxygen concentration on penetration depth is studied. Preliminary results suggest that increasing electron current density increases solvated electron concentration at the interface but decreases penetration depth, a result corroborated by previous works. Chemical pathways leading to the production of reactive oxygen and nitrogen species in both the gas and liquid phases are also analyzed. [Preview Abstract] |
Friday, October 9, 2020 2:00PM - 2:15PM Live |
YF3.00005: Probing the relationship between plasmas self organization and plasma induced fluid circulation in 1 ATM DC glows with liquid anode Zimu Yang, Yao Kovach, Janis Lai, John Foster The origin of plasma self organization in DC glows with liquid anode is still not well understood. Above a threshold current, the pattern appears for a given electrolyte. Also observed during self organization is fluid circulation. This circulation is observed both in the plane of the liquid (on surface) and normal to the plasma-liquid interface. The normal circulation gives rise to non-local flow field that enhances overall solution mixing. This work uses particle image velocimetry to map both surface and normal flow fields. More importantly, these measurements allow us to determine if the flows change with self organization. The measurements also yield insight into why the chemical properties of the solution are so stratified. That is, observed solution pH and conductivity changes seem to be local and thus at a certain depth below the surface, there is no change in these parameters. This spatial difference may be enhanced due to this forced convection induced by plasma contact. [Preview Abstract] |
Friday, October 9, 2020 2:15PM - 2:30PM Live |
YF3.00006: Time-resolved imaging of pulsed positive nanosecond discharge on water surface Ahmad Hamdan, James Diamond Pulsed nanosecond discharges produce non-thermal plasmas that are highly promising for various applications as well as for fundamental investigations. The dynamics of such discharges are highly dependent on the experimental conditions, mainly the propagation medium. In this study, pulsed nanosecond discharges in air in-contact with water are investigated. The dynamics of the plasma emission has been unveiled using imaging technique with time resolution as short as 1 ns. Depending on the magnitude of the voltage, two discharges modes were observed: i) highly organized filaments and ii) intense and less organized plasma filaments. 1-ns resolved images showed that the highly organized filaments can be considered as plasma bullets that propagate at the water surface with a velocity of hundreds of m/s. Detailed analysis of the bullets number and of the discharge electrical characteristics of the discharge, have revealed that one bullet has a constant charge (few nC) independently of the discharges conditions. Such characteristic encouraged us to propose the plasma bullet as plasma quanta. [Preview Abstract] |
Friday, October 9, 2020 2:30PM - 2:45PM Not Participating |
YF3.00007: Advanced Oxidation Dose and Correlation with Contaminant Removal Kinetics in a Dielectric Barrier Discharge Plasma-water Reactor Joseph Groele, John Foster Plasma-water interaction generates a variety of reactive species that are transported into the liquid. Hydrogen peroxide and ozone are two reactive oxygen species with lifetimes that allow them to penetrate into the bulk liquid and react to form hydroxyl radicals in-situ for the non-selective oxidation of organic contaminants in the volume of treated water. De-ionized water is processed by the plasma-water reactor and the resulting aqueous hydrogen peroxide and ozone concentrations are measured as part of the advanced oxidation dose. De-ionized water is then spiked with a model contaminant and processed at the same power supply conditions, and the contaminant concentration is measured along with the residual peroxide and ozone. The experimental contaminant removal kinetics are compared with those predicted by conventional advanced oxidation process modelling using peroxide and ozone concentrations determined by the pristine de-ionized water dosing experiments. The correlation between the oxidation dose delivered by the plasma and the contaminant removal kinetics are investigated. [Preview Abstract] |
Friday, October 9, 2020 2:45PM - 3:00PM Not Participating |
YF3.00008: Characterization of Particle Emission in Atmospheric Pressure Plasma DC glow Yao Kovach, Zhehui Wang, John Foster Atmospheric pressure plasmas are currently being investigated for a number of applications ranging from wound healing to water purification. A particular class of these discharges is the 1 atm DC glow with liquid anode. Previously, when ferric chloride solution was applied as anode electrolytes, a luminous particle emission has been observed with a trajectory phenomenon at 100 mA. However, the mechanism of particle emission from the liquid anode still remaining study. Recently, three types of particle emission processes have been demonstrated using a high speed image camera with the exposure rates up to 30k frames per seconds. Besides the particle emitted from the local interface on liquid anode, it is observed that the particles emitted downward from the cathode while a bright cathode spot was existing. Particle emission was also initiated in the plasma column. In this type, an interesting explosion activity with a ball shaped structure in gas-liquid phase which formed after the explosion was explored. The characteristics of each emission was summarized and compared with their time resolved measurements. Importantly, these different typed particle emissions and associate plasma behaviors might give rises to enhance the study in dusty plasma related physics. [Preview Abstract] |
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