Bulletin of the American Physical Society
69th Annual Gaseous Electronics Conference
Volume 61, Number 9
Monday–Friday, October 10–14, 2016; Bochum, Germany
Session ET3: Plasma Liquid InteractionsFocus
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Chair: Keisuke Takashima, Tohoku University Room: 2b |
Tuesday, October 11, 2016 11:00AM - 11:30AM |
ET3.00001: Control of Reactive Species Generated by Low-frequency Biased Nanosecond Pulse Discharge in Atmospheric Pressure Plasma Effluent Invited Speaker: Keisuke Takashima The control of hydroxyl radical and the other gas phase species generation in the ejected gas through air plasma (air plasma effluent) has been experimentally studied, which is a key to extend the range of plasma treatment. Nanosecond pulse discharge is known to produce high reduced electric field (E/N) discharge that leads to efficient generation of the reactive species than conventional low frequency discharge, while the charge-voltage cycle in the low frequency discharge is known to be well-controlled. In this study, the nanosecond pulse discharge biased with AC low frequency high voltage is used to take advantages of these discharges, which allows us to modulate the reactive species composition in the air plasma effluent. The utilization of the gas-liquid interface and the liquid phase chemical reactions between the modulated long-lived reactive species delivered from the air plasma effluent could realize efficient liquid phase chemical reactions leading to short-lived reactive species production far from the air plasma, which is crucial for some plasma agricultural applications. [Preview Abstract] |
Tuesday, October 11, 2016 11:30AM - 11:45AM |
ET3.00002: Chemical reaction by plasma in gas-liquid two-phase flow system Motonobu Goto, Kakeru Mano, Yui Hayashi, Noriharu Takada, Hideaki Kanda Two plasma processes using gasliquid two-phase flow were developed. One is gas/liquid slug flow in capillary glass tube where gas bubbles moved stably in liquid flow. Plasma was generated in bubbles by pulsed bipolar voltage and the liquid phase was mixed by circulated convection due to shearing force. As a gas, air, argon, helium, oxygen, or nitrogen was used. The pulsed bipolar voltage of 10 kV was applied at 10 kHz. The generated plasma was evaluated by ICCD image and high speed camera. The optical emission spectra was analyzed to identify the active species. By using this process, organic compound dissolved in liquid aqueous phase was reacted with oxidation. Another process was creeping plasma on flowing liquid film along glass tube outer surface. Owing to the thin film thickness, organic compound dissolved in liquid phase was reacted effectively. Therefore, effective reaction process could be established in gas/liquid two-phase flow by controlling the gas/liquid flow. [Preview Abstract] |
Tuesday, October 11, 2016 11:45AM - 12:00PM |
ET3.00003: Plasma charging and electron-based reactions at the plasma-liquid interface of an isolated liquid droplet Paul Maguire, Charles Mahony, Colin Kelsey, David Rutherford, Davide Mariotti, Declan Diver The study of plasma-liquid interactions opens up exciting new opportunities for applications but numerous investigative challenges remain. The use of isolated and stable spherical liquid microdroplets in a non-thermal equilibrium atmospheric pressure plasma offers a new platform for experimental and theoretical investigations. Since the droplet assumes floating potential, a high flux of electrons with low net energy (\textasciitilde thermal) becomes fixed and solvated within the first monolayers of the liquid leading to highly reactive and rapid chemical reactions. We observe such reactions, e.g. H2O2 and metal nanoparticle formation, at rates that are much higher than reported elsewhere. Since the isolated droplet radius is greater than Debye lengths and mean free paths, we have an opportunity to directly compare, for the first time, long-standing collisional probe theories in this important regime. We measure a lower bound average charge of \textgreater 1E5 electrons on a 13um droplet. Simulations of unipolar corona charging for this size predict \textasciitilde 1E3 electrons. A Comsol-based drift-diffusion model is currently under development and so far experiment and theory match within \textasciitilde 1 order of magnitude but improvements in measurement technique are in progress. [Preview Abstract] |
Tuesday, October 11, 2016 12:00PM - 12:15PM |
ET3.00004: Reacting chemistry at the air-water interface Tomoyuki Murakami, Thomas Morgan, Lutz Huwel, William Graham Plasma interaction with gas-liquid interfaces is becoming increasingly important in biological applications, chemical analysis and medicine. It introduces electrons, new ionic species and reactive species and contributes to chemical and electrical self-organization at the interface. To provide insight into the associated physics and chemistry at work in the evolution of the plasma in the air-water interface (AWI), a time-dependent one-dimensional modelling has been developed. The numerical simulation is used to solve the kinetic equations and help identify the important reaction mechanisms and describe the phenomena associated with hundreds of reacting pathways in gas-phase and liquid-phase AWI chemistry. [Preview Abstract] |
Tuesday, October 11, 2016 12:15PM - 12:30PM |
ET3.00005: Transient Species in Plasmas Interacting with Liquids S. Reuter, A. Schmidt-Bleker, J. H. van Helden, H. Jablonowski, J. Winter, J. Santos Sousa, M. Gianella, G. Ritchie, K.-D. Weltmann Processes of non-equilibrium plasmas at gas-liquid interfaces are determined by transient species. Quantification of these species in the plasma, gas, or liquid is intricate and requires specific diagnostics. In order to study plasma-liquid interaction processes, novel diagnostic concepts need to be developed combined with simulations that allow an insight into the chemical reaction pathways. Significantly relevant transient species in plasmas operated in ambient air include HO$_{\mathrm{2}}$ and O$_{\mathrm{2}}$(a$^{\mathrm{1}}\Delta )$, which are diagnosed in this work. The aim is to link localized transient species with longer living stable species in the gas phase and in the liquid phase. Understanding reaction pathways makes it possible to control the reactive species composition generated by the cold plasmas, and further insight into plasma induced reactivity in condensed matter systems can be gained. The work shows a combination of absorption spectroscopic methods and other diagnostic techniques as well as simple kinetics modeling as a way to control the plasma chemical reactions. [Preview Abstract] |
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