Bulletin of the American Physical Society
68th Annual Gaseous Electronics Conference/9th International Conference on Reactive Plasmas/33rd Symposium on Plasma Processing
Volume 60, Number 9
Monday–Friday, October 12–16, 2015; Honolulu, Hawaii
Session OR1: Plasma Interaction with Liquids I |
Hide Abstracts |
Chair: Fumiyoshi Tochikubo, Tokyo Metropolitan University Room: 301 B |
Thursday, October 15, 2015 10:00AM - 10:15AM |
OR1.00001: Production of water mist from electrolyte surface in contact with atmospheric-pressure dc helium glow plasma K. Sasaki, H. Ishigame, S. Nishiyama Plasma-liquid interaction is a new subject which has been opened by developments of atmospheric-pressure plasma sources. In this work, we adopted laser Mie scattering to examine an atmospheric-pressure dc helium glow plasma in contact with NaCl solution. The plasma was produced by applying a dc voltage between a stainless-steel gas nozzle and the electrolyte via a register of 100 k$\Omega$. The gap distance between the electrolyte surface and the electrode was 4 mm. Helium as a working gas was fed from the nozzle toward the electrolyte surface. The discharge space was illuminated using a cw laser beam at a wavelength of 457 nm, and the scattered laser light was captured using a high-speed camera with an image intensifier via an interference filter at the laser wavelength. The scattered laser light told us the existence of particulates or water mists in the discharge space. The water mists were produced from the electrolyte surface explosively as well as randomly. The trajectories of the mists were basically parabolic. We sometimes observed the expansion of the mist size in the gas phase. The expansion was followed by the disappearance of the mist. This may be due to the evaporation of the mist, and is considered to be the production mechanism of Na in the gas phase. [Preview Abstract] |
Thursday, October 15, 2015 10:15AM - 10:30AM |
OR1.00002: Precision charging of microparticles in plasma via the Rayleigh instability for evaporating charged liquid droplets Euan Bennet, Charles M.O. Mahony, Hugh E. Potts, Paul Everest, David Rutherford, Sadegh Askari, Colin Kelsey, Fatima Perez-Martin, Neil Hamilton, David A. McDowell, Davide Mariotti, Paul Maguire, Declan A. Diver In this paper we describe a novel method for delivering a precise, known amount of electric charge to a micron-sized solid target. Aerosolised microparticles passed through a plasma discharge will acquire significant electric charge. The fluid stability under evaporative stress is a key aspect that is core to the research. Initially stable charged aerosols subject to evaporation (i.e. a continually changing radius) may encounter the Rayleigh stability limit. This limit arises from the electrostatic and surface tension forces and determines the maximum charge a stable droplet can retain, as a function of radius. We demonstrate that even if the droplet charge is initially much less than the Rayleigh limit, the stability limit will be encountered as the droplet evaporates. The instability emission mechanism is strongly linked to the final charge deposited on the target, providing a mechanism that can be used to ensure a predictable charge deposit on a known encapsulated microparticle. [Preview Abstract] |
Thursday, October 15, 2015 10:30AM - 10:45AM |
OR1.00003: Controlled Microdroplet Transport {\&} Charging in an Atmospheric Pressure Microplasma Colin Kelsey, Paul Maguire, Charles Mahony, Neil Hamilton, Davide Mariotti, David Rutherford, David McDowell, F\'atima P\'erez-Mart\'In, Euan Bennet, Hugh Potts, Declan Diver We have measured charge and evaporation rates of a stream of micron-scale H$_{2}$O droplets transported through a low-temperature helium-neon rf plasma. N$_{\mathrm{e}}$ and T$_{\mathrm{e}}$, estimated from plasma impedance, were $\sim$ 10$^{13}$/cm$^{3}$ and $\sim$ 5eV respectively; gas temperature, from N$_{2}$ spectroscopy, was \textless 400K. With a log-normal aerosol droplet size distribution, 15 micron CMD and droplet velocity distribution within a parabolic envelope of $\sim$ 75{\%} of the local gas speed, the plasma induced evaporation caused an average diameter reduction of \textless 2 microns. This is equivalent to an average evaporation rate $\sim$ 2 orders of magnitude higher than reported for similar droplets in a comparable gas flow without plasma. Using charged droplet collection and current amplification, we have measured sub-millisecond charge pulses of up to 10$^{7}$e from a droplet stream with $\sim$ 2.5x10$^{3}$ droplets/s demonstrating the transport of droplets beyond the plasma and recombination region with negative charge retained. Time averaged measurements using an alternative technique show the mean charge per droplet is $\sim$ 10$^{5}$e. Results from an enhanced resolution charge measurement apparatus, currently being tested and using individual and size selectable droplets will be reported. \\[4pt] [1] P. Maguire et al: Appl. Phys. Lett. 106 (2015) 224101 [Preview Abstract] |
Thursday, October 15, 2015 10:45AM - 11:00AM |
OR1.00004: Bubble Phenomena caused by High Repetitive Plasmas in Water Masahiro Akiyama, Takuma Oikawa, Masatoshi Fue, Ryoma Ogata, Koich Takaki, Hidenori Akiyama Streamer discharges in water were generated by a pulsed power generator. The streamer shape changed depending on pulse repetition rate. Streamer discharges at 500 pulses per second (pps) resulted in a ball shape. Under this formation, small bubbles gather near the electrode tip. Our aims are the analysis and discussion of the bubble phenomena caused by high repetitive plasmas produced in water. Pulsed power with a maximum output of 1 J/pulse was applied to an electrode of 0.8 mm in diameter covered by an insulator of 2 mm thickness. The electrode was inserted into tap water with conductivity of 170 uS/cm. The polarity was positive. Phenomena, in which the resulting gas bubbles oscillate and gather, were found to have an important role in producing ball shape streamer discharges. [Preview Abstract] |
Thursday, October 15, 2015 11:00AM - 11:15AM |
OR1.00005: The Time Evolution of Streamer Discharges in Single and Multiple Bubbles in Water Selman Mujovic, Joseph Groele, John Foster The interaction of plasma with liquid water lies at the heart of a variety of revisited technological applications ranging from water treatment to wound healing. Plasma ignition and propagation in water, however, is poorly understood. It has been theorized that plasma streamer propagation takes place in microbubbles, namely streamer bubble hopping. In this work, discharge development in single and multiple bubble acoustic systems is investigated using high-speed imaging and emission spectroscopy. Optical filters allow for time resolved measurements of specific chemical species as well. Better understanding of these breakdown processes will guide the construction of an effective plasma water purifier. [Preview Abstract] |
Thursday, October 15, 2015 11:15AM - 11:30AM |
OR1.00006: Multi-physics study of plasma in liquids: The case of Plasma Electrolytic Oxidation (PEO) Alexandre Nomine, Sam Troughton, Anna Nomine, Gerard Henrion, Bill Clyne PEO is a promising technique in order to grow rapidly oxide coatings with high corrosion and wear resistance. Oxidation is driven by millions of simultaneous micro-discharges (MD) that occur at the interface between the substrate and the liquid electrolyte. However, the mechanisms of breakdown and the subsequent oxidation are not well understood yet. Current profiles and Ultra-Fast Imaging of single discharges allows to correlate the size and life-time of the discharge with different electric parameters (Q, Imax). MD are found to appear in cascade, switching on and off with a frequency in the order of 1--10 kHz. Formation of a bubble is observed directly after the ignition of the discharge. The growth rate that varies between 1 and 10 m/s, is used to estimate the gas pressure in the bubble. The influence of the pulse frequency on the bubble shape and on the coatings will be presented. MD size and life time are known to increase with coating thickness presumably due to higher charge accumulation. This study shows that ms scale, the evolution of MD size and life time evaluates similarly, suggesting that the coating thickness is not the only parameter governing the MD size and life-time. [Preview Abstract] |
Thursday, October 15, 2015 11:30AM - 11:45AM |
OR1.00007: Optical Emission Spectroscopy of Microplasma Discharge in Sea Water Vladislav Gamaleev, Akimitsu Hatta, Hiroshi Furuta, Jun-Seok Oh, Yo Okamura, Kensuke Kitamura, Yusuke Hashimoto We have been investigating microplasma discharge in sea water for optical emission spectroscopy. Microplasma discharge in artificial sea water (10ASW) was carried using needle-to-plane platinum electrode system. The gap, between electrodes, was ranged from 10 to 60 microns. The electricity source was impulse generatorwith MOSFET switch and variable capacitance and inductance. The maximum voltage and current for this scheme were respectively 1kV and 10A, pulse width 10 $\mu $s. It has been confirmed that, using the micro-gap configuration, spark discharges were ignited at the conventional breakdown voltages below 1kV, even in the conductive sea water. Was noted formation of small bubbles before of the plasma ignition process. The mechanism of formation of these bubbles is mostly Joule heating because of high currents. It has been speculated that plasma discharge initiates in bubbles. Optical emission spectroscopy of microplasma in sea water was carried. In the spectra, emission peaks for H, O, Na, Mg, Ca, Cl and Pt were clearly detected. Besides the main components of 10ASW, contaminants from the electrodes appeared in the spectra. The characteristics of microplasma discharge in sea water and analysis of the optical emission spectra will be presented. [Preview Abstract] |
Thursday, October 15, 2015 11:45AM - 12:00PM |
OR1.00008: Simulation of plasma discharge in liquids: A detailed two-phase fluid approach Ali Charchi Aghdam, Tanvir Farouk Plasma discharge in liquids has gained great attention recently due to its applications in biomedical engineering, fuel processing, and water treatment and so on. Despite the tremendous interest, a comprehensive understanding of the underlying physics still remains limited. In the current work, an attempt is made to present a mathematical multi-physics model to describe the discharge of plasma in liquids. An in-house modeling platform is developed for simulating plasma formation in multiphase fluids. The model resolves a detailed two-phase fluid including viscous effects, surface tension, gravitational forces and electrical body force. All the governing equations are solved for gas and liquid phases. Electric field and charged species equations along with the plasma reaction kinetics are solved to get the charge distribution in the different phases as well as at the gas-liquid interface to obtain the electric body force acting at the interface. By coupling the above sub-models, a comprehensive multi-physics model for plasma discharge in liquids is constructed which is able to capture several physical aspects of the phenomena especially the role of the bubble, its motion and distortion on plasma characteristics. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700