Bulletin of the American Physical Society
52nd Annual Meeting of the APS Division of Plasma Physics
Volume 55, Number 15
Monday–Friday, November 8–12, 2010; Chicago, Illinois
Session JO7: Plasma Applications |
Hide Abstracts |
Chair: Yevgeny Raitses, Princeton Plasma Physics Laboratory Room: Columbus IJ |
Tuesday, November 9, 2010 2:00PM - 2:12PM |
JO7.00001: Interaction of atmospheric pressure plasmas with dry and wet wounded skin Natalia Babaeva, Mark Kushner Non-equilibrium plasmas in direct contact with living tissue can produce therapeutic effects. Dielectric barrier discharge (DBD) devices used for this purpose contain the powered electrode while the tissue being treated is usually the floating electrode. The plasma produces beneficial effects through: (i) electric fields, (ii) production of radicals and charged species, (iii) photons and (iv) energetic ions impinging onto wounds and tissue surfaces. Using a 2-d plasma hydrodynamics model, we discuss the interaction of DBD filaments with human skin. We model the propagation of the streamer across the gap, its intersection with skin, the charging of cell surfaces and the generation of conduction and displacement currents, and electric fields in the cells. The cellular structure in the first few mm of human skin is incorporated into the computational mesh with permittivity and conductivity to represent the electrical properties of the intra- and inter-cell structures. In this talk, we concentrate on the effects of plasmas on open wounds which are either dry or filled with blood serum. We will discuss the penetration of electric fields through the blood serum and into the underlying cells, including the possible interactions with blood platelets, and the distribution of ion energies onto the liquid and cellular surfaces. [Preview Abstract] |
Tuesday, November 9, 2010 2:12PM - 2:24PM |
JO7.00002: Propagation of an Ionization Front of Hydrogen Plasma Driven by Pulsed High Voltage under High Pressure Chieh-Wen Lo, Satoshi Hamaguchi Plasmas generated at or near atmospheric pressure with low gas temperature have a variety of industrial applications. A typical method to generate such high-pressure non-thermal plasmas is to apply nanosecond-scale pulsed voltage. The goal of this study is to understand the fundamental physics and formation mechanism of such plasmas, using numerical simulations. In this study, we have employed 1d2v particle-in-cell (PIC) simulations with Monte Carlo (MC) collisions to study nanosecond parallel plate hydrogen discharges near atmospheric pressure, especially focusing on the ionization wave propagation in the discharge formation phase. Recently the dynamics of such discharges has been studied in detail experimentally and our simulation results have reproduced the experimental observations with reasonable accuracy. The simulations have also revealed that, despite the high collisionality, electrons in the cathode region transiently exhibit strongly non-Maxwellian energy distributions. Since the majority of ionization of this system occurs in this region, kinetic treatment is likely to be essential in accurate analysis of such systems. [Preview Abstract] |
Tuesday, November 9, 2010 2:24PM - 2:36PM |
JO7.00003: Microwave Plasma Assisted Combustion of Premixed Ar/CH$_{4}$ and He/CH$_{4}$ Gases at Atmospheric Pressure Chuji Wang, Nimisha Srivastava, Burak Malik Kaya Low-temperature nonthermal plasma assisted combustion is of growing interest due to potential applications in the improvement of combustion efficiency, reduction of ignition delay time, fuel reforming, etc. A 2.45 GHz microwave plasma source was used to study the microwave plasma enhanced flame of premixed Ar/CH$_{4}$ and He/CH$_{4}$ gases at atmospheric pressure. We present the visual observations of the plasma-assisted flames sustained at different mixing ratios of Ar/CH$_{4}$ and He/CH$_{4}$ gases. Optical emission spectroscopy (OES) was employed to study the reactive species generated from plasma flame. Visual imaging clearly showed the effect of microwave power and difference in flame shapes created in the Ar/CH$_{4}$ and He/CH$_{4}$ combustion: for Ar/CH$_{4}$ continuous flames were observed; for He/CH$_{4}$ floating flames (flames sustained with an air-gap from the plasma orifice) were observed at low plasma powers and some particular gas mixing ratios of He/CH$_{4}$. Measured flame temperatures were much higher than plasma gas temperatures. Reactive species, such as OH, NO, N$_{2}$, and C$_{2}$, were observed using OES. Effect of various gas mixing ratios, flow rates, and plasma powers on flame shape and flame temperature were also studied. [Preview Abstract] |
Tuesday, November 9, 2010 2:36PM - 2:48PM |
JO7.00004: Effect of Addition of Water Vapor on OH Radical Concentration in an Atmospheric Pressure Microwave Argon Plasma Jet Nimisha Srivastava, Chuji Wang, Sterling Harper In recent years, role of reactive plasma species such as OH and O in various plasma treatments and combustion applications are topics of investigation and debate. Quantitative study of OH radicals in atmospheric plasma jets can contribute to the better understanding of OH generation mechanism and to optimization of plasma treatment processing and plasma source designs. A 2.45 GHz microwave plasma source was used to study the effect on OH radical generation in an argon atmospheric pressure plasma jet with addition of H$_{2}$O vapor. OH radical number densities were measured along the plasma jet axis using UV cavity ringdown spectroscopy of OH (A--X) (1 -- 0) band at 308 nm. Addition of water vapor results in reduction of plasma column jet length and increases gas temperature. Optical emission spectroscopy clearly shows that dominant reactive species in pure Ar plasma jet changed from N$_{2}$ to OH with the addition of water vapor. The absolute number densities of OH varied along the jet axis from 7.4$\times $10$^{14}$ to 3.7$\times $10$^{16}$, 4.3$\times $10$^{14}$ to 5.0$\times $10$^{16}$, and 4.6$\times $10$^{14}$ to 3.4$\times $10$^{16}$ molecule/cm$^{3}$ for the addition of 0 ppm, 4 ppm, and 7 ppm water vapor, respectively. [Preview Abstract] |
Tuesday, November 9, 2010 2:48PM - 3:00PM |
JO7.00005: ABSTRACT WITHDRAWN |
Tuesday, November 9, 2010 3:00PM - 3:12PM |
JO7.00006: Depletion of High-Energy Electrons in Ar/Ne Inductively-Coupled Plasmas A.E. Wendt, R.O. Jung, John B. Boffard, Chun C. Lin Electrons in bounded, low-pressure plasmas are confined electrostatically by an electric potential difference between the plasma and vessel walls. Electrons with sufficiently large kinetic energy, however, can overcome this potential difference and escape to the walls. The electron energy distribution function (EEDF) of inductively coupled plasmas often takes the form of a Maxwell-Boltzmann distribution at low energies, but with relatively depleted numbers of high energy electrons, sometimes attributed to electron wall losses. While the electrons in this high energy range ($>$12 eV) are often those most critical for driving plasma chemistry, this energy range is also difficult to measure with Langmuir probes. A simple analytic EEDF expression has been developed to account for electron losses in a system with an otherwise Maxwellian EEDF. After accounting for oscillations in the confining potential due to RF fluctuations in plasma potential, the modified Maxwellian agrees well with optical and Langmuir probe measurements of time-averaged EEDFs in Ar and Ar/Ne inductively coupled plasmas, and is well approximated by the two-parameter $(x,T_x)$ form, $f_x(E)=c_1T_x^{-3/2}E^{-1/2}\exp [-c_2(E/T_x)^x]$ with $x\simeq 1.2$. [Preview Abstract] |
Tuesday, November 9, 2010 3:12PM - 3:24PM |
JO7.00007: The high flux plasma generator Magnum-PSI H.J.N. van Eck, A.W. Kleyn, W.R. Koppers, J. Rapp, P.A. Zeijlmans van Emmichoven Magnum-PSI is a magnetized (3 T), high-flux (up to 10$^{24}$ H$^{+}$ ions m$^{-2}$s$^{-1})$ plasma generator, capable of delivering 10 MW m$^{-2}$ steady-state power fluxes to a large area target. Magnum-PSI is a highly accessible laboratory experiment in which the interaction of magnetized plasma with different surfaces can be studied. This experiment will provide new insights in the complex physics and chemistry that will occur in the divertor region of the future experimental fusion reactor ITER and reactors beyond ITER. In this contribution, we will present the design and characterization of the Magnum-PSI experiment. The differentially pumped vacuum system, the superconducting magnet, the plasma source, the target plate and manipulator will be presented. Simulations and measurements of the neutral gas flow, as well as electron density and temperature measurements of the plasma beam will be presented. Furthermore, a flavor of upcoming PSI experiments will be given. [Preview Abstract] |
Tuesday, November 9, 2010 3:24PM - 3:36PM |
JO7.00008: Non-Perturbative Measurements of Silane-Ammonia Plasma Parameters and Correlation with Silicon Nitride Deposition Properties Adam Steiner, Daniel Hoffman, Steven Shannon Plasma-enhanced chemical vapor deposition (PECVD) of thin solid films is a topic of interest as an enabling manufacturing technology for current and future industries. A series of silicon nitride deposition plasmas were generated on a laboratory-scale, capacitively coupled PECVD system under a variety of process conditions (pressure, flow, power, RF frequency) from silane-ammonia mixtures. Voltage-current measurements were recorded using an in-line RF probe; film thickness and uniformity were measured using ellipsometry. A multi-species plasma model was developed based on particle-energy balance and plasma circuit modeling to obtain time-resolved electron temperature, number density, and sheath voltage from the measured electrical data. The results of correlating average plasma parameters with deposition characteristics will be given, and the model for determining real-time parameters of a two-species plasma from VI measurements will be presented. [Preview Abstract] |
Tuesday, November 9, 2010 3:36PM - 3:48PM |
JO7.00009: The role of oxygen in analytical glow discharges: GD-OES and GD-ToF-MS studies Sohail Mushtaq, Juliet C. Pickering, Edward B.M. Steers, Peter Horvath, James A. Whitby, Johann Michler The influence of up to 0.8 {\%} O$_{2}$ on the Ar plasma in a dc analytical glow discharge was studied on Fe, Ti, Cu and Au samples using time of flight mass spectrometry and high resolution optical Fourier transform spectrometry. All positive ion signals decreased gradually by 2 to 3 orders of magnitude with increasing O$_{2}$. In addition, a sudden 100-fold drop of the ion signals also occurred for Fe and Ti samples at 0.1 {\%} and 0.05 {\%} O$_{2}$ concentrations, respectively. Optical emission spectra of Fe~I, Fe~II, Ti~I and Ti~II in Ar/O$_{2}$ plasmas also showed a sudden drop of intensity at the same concentrations. This was accompanied by a 20-fold drop in sputter rate for Fe and Ti, whereas the sputter rate changed less for Cu and only slightly for Au. The role of surface and gas-phase processes will be discussed in the presentation. [Preview Abstract] |
Tuesday, November 9, 2010 3:48PM - 4:00PM |
JO7.00010: Dynamic Control of Microwave Plasma Sources for Material Processing by Using Hyper-Simulation Yasuyoshi Yasaka, Akihiro Tsuji Uniformity of etching or deposition over a wafer is one of the key features for plasma processing with large-size wafers. The uniformity can be measured as a result of a process, and correction or improvement of the uniformity is made by changing device parameters such as power levels, gas flow rates, timings, and so on. Evaluation and control are, however, not combined or unified as a problem of plasma physics. They are assigned as the input and output of a black box of empirical transfer function obtained by expert systems or neural networks. We are going to establish a novel control system based on physics, in which a fluid simulation is used to obtain a power deposition profile necessary to produce the two-dimensional density distribution of desire. A control system of a microwave slot antenna then changes power distribution dynamically according to the output of the simulation. It should be noted that this simulation has inputs and outputs opposite to conventional ones, which, we call hyper-simulation, is one of the novel features of the control system. [Preview Abstract] |
Tuesday, November 9, 2010 4:00PM - 4:12PM |
JO7.00011: Improving Efficiency of Diamond Thin Film Deposition In an ECR Sputter Source Michael Newby, Jerry Ross, Andrew Zwicker Having some of the most extreme physical properties of any material, diamond thin films are used to reinforce vacuum windows, as a semiconductor in electronic devices and to coat knives among other things. In our experiment, a 5 KW microwave ignites Argon or Hydrogen-Methane gas to create plasma at a low pressure which sputters a graphite target to create a diamond thin film on silicon substrates. The microwave matching system used to do this has an output frequency of 2.45GHz which is sent through a SmartMatch AX3060 impedance matching tuner. The SmartMatch uses three tuning stubs to match the load impedance and optimize the microwave power into the plasma. Problems arise when the SmartMatch tunes to something other than the plasma, such as the o-rings at the quartz window vacuum interface. This project focused on troubleshooting these issues by enabling the control of and communication with the microwave matching system. [Preview Abstract] |
Tuesday, November 9, 2010 4:12PM - 4:24PM |
JO7.00012: Application of the Thermoelectric Effect on the Liquid Lithium Heat Transfer Wenyu Xu, Vijay Surla, David Ruzic Recently liquid lithium has drawn a lot of interest due to its large potential to suppress hydrogen recycling and lower the impurity level in tokamaks. A series of experiments have been conducted on Solid/Liquid Lithium Divertor Experiment (SLiDE) facility at the University of Illinois which found that the thermoelectric effect is responsible for enabling the liquid lithium to absorb power, such as the 60 MW/m2 e-beam spot on CDX-U, without significant evaporation. Taking advantage of the observed results in SLiDE, a new concept called Lithium / Molybdenum Infused Trenches (LIMIT) is developed. In this design, millimeter thick trenches are used to hold the flowing liquid lithium by capillary force, while the flow of lithium is still driven by thermoelectric force. The lithium trenches are 2 mm thick, 10 mm deep and 90 mm long. A 5 mm gap between the trenches and the stainless steel tray is formed to conduct the back flow. A linear electron beam generating almost 1MW/m2 heat flux is used to heat the surface of the stainless steel trenches with a small impact angle and the magnetic field is at the same direction as the beam. The detailed heat flux analysis using existing diagnostics, with LIMIT structure housed in SLiDE, is presented. [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