WorldWideScience

Sample records for plasma discharge result

  1. Plasma Discharges in Gas Bubbles in Liquid Water: Breakdown Mechanisms and Resultant Chemistry

    Science.gov (United States)

    Gucker, Sarah M. N.

    The use of atmospheric pressure plasmas in gases and liquids for purification of liquids has been investigated by numerous researchers, and is highly attractive due to their strong potential as a disinfectant and sterilizer. However, the fundamental understanding of plasma production in liquid water is still limited. Despite the decades of study dedicated to electrical discharges in liquids, many physical aspects of liquids, such as the high inhomogeneity of liquids, complicate analyses. For example, the complex nonlinearities of the fluid have intricate effects on the electric field of the propagating streamer. Additionally, the liquid material itself can vaporize, leading to discontinuous liquid-vapor boundaries. Both can and do often lead to notable hydrodynamic effects. The chemistry of these high voltage discharges on liquid media can have circular effects, with the produced species having influence on future discharges. Two notable examples include an increase in liquid conductivity via charged species production, which affects the discharge. A second, more complicated scenario seen in some liquids (such as water) is the doubling or tripling of molecular density for a few molecule layers around a high voltage electrode. These complexities require technological advancements in optical diagnostics that have only recently come into being. This dissertation investigates several aspects of electrical discharges in gas bubbles in liquids. Two primary experimental configurations are investigated: the first allows for single bubble analysis through the use of an acoustic trap. Electrodes may be brought in around the bubble to allow for plasma formation without physically touching the bubble. The second experiment investigates the resulting liquid phase chemistry that is driven by the discharge. This is done through a dielectric barrier discharge with a central high voltage surrounded by a quartz discharge tube with a coil ground electrode on the outside. The plasma

  2. Modeling electronegative plasma discharge

    Energy Technology Data Exchange (ETDEWEB)

    Lichtenberg, A.J.; Lieberman, M.A. [Univ. of California, Berkley, CA (United States)

    1995-12-31

    Macroscopic analytic models for a three-component electronegative gas discharge are developed. Assuming the negative ions to be in Boltzmann equilibrium, a positive ion ambipolar diffusion equation is derived. The discharge consists of an electronegative core and electropositive edges. The electron density in the core is nearly uniform, allowing a parabolic approximation to the plasma profile to be employed. The resulting equilibrium equations are solved analytically and matched to a constant mobility transport model of an electropositive edge plasma. The solutions are compared to a simulation of a parallel-plane r.f. driven oxygen plasma for p = 50 mTorr and n{sub eo}= 2.4 x 10{sup 15} m{sup -3}. The ratio {alpha}{sub o} of central negative ion density to electron density, and the electron temperature T{sub e}, found in the simulation, are in reasonable agreement with the values calculated from the model. The model is extended to: (1) low pressures, where a variable mobility model is used in the electropositive edge region; and (2) high {alpha}{sub o} in which the edge region disappears. The inclusion of a second positive ion species, which can be very important in describing electronegative discharges used for materials processing, is a possible extension of the model.

  3. Plasma discharge in N2 + CH4 at low pressures - Experimental results and applications to Titan

    Science.gov (United States)

    Thompson, W. Reid; Henry, Todd J.; Schwartz, Joel M.; Khare, B. N.; Sagan, Carl

    1991-01-01

    Results are reported from laboratory continuous-flow plasma-discharge experiments designed to simulate the formation of hydrocarbons and nitriles from N2 and CH4 in the atmosphere of Titan. Gas-chromatography and mass-spectrometry data were obtained in experiments lasting up to 100 h at temperature 295 K and pressure 17 or 0.24 mbar, modeling (1) cosmic-ray-induced processes in the Titan troposphere and (2) processes related to stratospheric aurorae excited by energetic electrons and ions from the Saturn magnetosphere, respectively. The results are presented in extensive tables and graphs, and the 0.24-mbar yields are incorporated into an eddy-mixing model to give stratospheric column abundances and mole fractions in good agreement with Voyager IRIS observations.

  4. Electrosurgical Plasma Discharges

    Science.gov (United States)

    Stalder, K. R.; Woloszko, J.

    2002-10-01

    Electrosurgical instruments employing plasmas to volumetrically ablate tissue are now enjoying widespread use in medical applications. We have studied several commercially available instruments in which luminous plasma discharges are formed near electrodes immersed in saline solutions when sufficiently large amplitude bipolar voltage waveforms are applied. Different aqueous salt solutions have been investigated, including isotonic NaCl solution as well as solutions of KCl, and BaCl_2. With strong driving voltage applied, a vapor layer is formed as well as visible and UV optical emissions. Spectroscopic measurements reveal the predominant emissions are from the low ionization potential salt species, but significant emissions from electron impact dissociated water fragments such as OH and H-atoms also are observed. The emissions also coincide with negative bias on the active electrode. These optical emissions are consistent with an electron density of about 10^12cm-3 and an electron temperature of about 4 eV. Experimental results and model calculations of the vapor layer formation process and plasma formation in the high-field region will be discussed.

  5. Theory of gas discharge plasma

    CERN Document Server

    Smirnov, Boris M

    2015-01-01

    This book presents the theory of gas discharge plasmas in a didactical way. It explains the processes in gas discharge plasmas. A gas discharge plasma is an ionized gas which is supported by an external electric field. Therefore its parameters are determined by processes in it. The properties of a gas discharge plasma depend on its gas component, types of external fields, their geometry and regimes of gas discharge. Fundamentals of a gas discharge plasma include elementary, radiative and transport processes which are included in its kinetics influence. They are represented in this book together with the analysis of simple gas discharges. These general principles are applied to stationary gas discharge plasmas of helium and argon. The analysis of such plasmas under certain conditions is theoretically determined by numerical plasma parameters for given regimes and conditions.

  6. Plasma Characteristics of Electrosurgical Discharges*

    Science.gov (United States)

    Stalder, Kenneth R.

    2003-10-01

    Surgical devices utilizing electrical discharges of ever increasing sophistication have been used for decades for numerous procedures. Cushing and Bovie in 1928, for example, developed high-frequency spark generators to cauterize blood vessels and remove unwanted tissue by a thermal ablation processes. Modern Bovies (named after their inventor) use a high-frequency discharge from an electrode to nearby tissue to thermally ablate tissue. Spectroscopic analysis shows that these discharges are hot and are well represented by a thermal equilibrium model, and temperatures near 2000 K are easily achieved. New electrosurgical devices utilizing repetitive electrical discharges in a conducting saline environment have recently been developed. Electron emission from an active electrode during certain portions of the voltage waveform causes the formation of a vapor layer surrounding the electrode and the subsequent ionization and dissociation of species in this region. Electron temperatures of approximately 4 eV are achieved during the plasma phase. Water molecules are dissociated into reactive fragments, and the salt species are also excited and ionized in this nonequilibrium plasma. It is thought that the reactive species interact with nearby tissue, causing localized tissue removal (ablation) which surgeons can exploit during surgical procedures. Flowing saline surrounding the plasma region cools untargeted tissue and removes the reaction products. This presentation will focus on experimental results of the plasma conditions and discuss our current efforts to understand the complex reactions of the various plasma species with tissue structures such as collagen. A short clip showing tissue removal will also be shown.

  7. Biological and Agricultural Studies on Application of Discharge Plasma and Electromagnetic Fields 2.Sterilization by Electrical Discharges and Plasmas

    Science.gov (United States)

    Watanabe, Takayuki

    The use of electrical discharges and plasmas for sterilization is reviewed. Plasmas generated by a silent discharge, a pulse discharge, and a radio frequency discharge under atmospheric pressure have been used for sterilization. Furthermore, a microwave plasma, a radio frequency plasma, and a low temperature plasma with hydrogen peroxide under low pressure conditions have been also used for sterilization. Sterilization results from injury caused by the discharge current, and from the reaction of species affected by the discharge. A silent discharge with air or oxygen is most effective for the sterilization. Nitrogen discharge also has a significant effect, however, argon discharge does not have a significant effect.

  8. Pulsed discharge plasmas in supercritical carbon dioxide

    OpenAIRE

    Kiyan, Tsuyoshi; Uemura, A.; Tanaka, K.; Zhang, C. H.; Namihira, Takao; Sakugawa, Takashi; Katsuki, Sunao; Akiyama, Hidenori; Roy, B.C.; Sasaki, M.; Goto, M.; キヤン, ツヨシ; ナミヒラ, タカオ; サクガワ, タカシ; カツキ, スナオ

    2005-01-01

    In recent years, several studies about electrical discharge plasma in supercritical carbon dioxide (CO2) have been carried out. One of the unique characteristics of supercritical fluid is a large density fluctuation near the critical point that can result in marked dramatic changes of thermal conductivity. Therefore, the electrical discharge plasma produced in supercritical fluid has unique features and reactions unlike those of normal plasma produced in gas phase. In our experiments, two typ...

  9. Helicon plasma thruster discharge model

    Energy Technology Data Exchange (ETDEWEB)

    Lafleur, T., E-mail: trevor.lafleur@lpp.polytechnique.fr [Laboratoire de Physique des Plasmas, CNRS, Sorbonne Universités, UPMC Univ Paris 06, Univ Paris-Sud, Ecole Polytechnique, 91128 Palaiseau, France and ONERA - The French Aerospace Lab, 91120 Palaiseau (France)

    2014-04-15

    By considering particle, momentum, and energy balance equations, we develop a semi-empirical quasi one-dimensional analytical discharge model of radio-frequency and helicon plasma thrusters. The model, which includes both the upstream plasma source region as well as the downstream diverging magnetic nozzle region, is compared with experimental measurements and confirms current performance levels. Analysis of the discharge model identifies plasma power losses on the radial and back wall of the thruster as the major performance reduction factors. These losses serve as sinks for the input power which do not contribute to the thrust, and which reduce the maximum plasma density and hence propellant utilization. With significant radial plasma losses eliminated, the discharge model (with argon) predicts specific impulses in excess of 3000 s, propellant utilizations above 90%, and thruster efficiencies of about 30%.

  10. Plasma Discharge Process in a Pulsed Diaphragm Discharge System

    Science.gov (United States)

    Duan, Jianjin; Hu, Jue; Zhang, Chao; Wen, Yuanbin; Meng, Yuedong; Zhang, Chengxu

    2014-12-01

    As one of the most important steps in wastewater treatment, limited study on plasma discharge process is a key challenge in the development of plasma applications. In this study, we focus on the plasma discharge process of a pulsed diaphragm discharge system. According to the analysis, the pulsed diaphragm discharge proceeds in seven stages: (1) Joule heating and heat exchange stage; (2) nucleated site formation; (3) plasma generation (initiation of the breakdown stage); (4) avalanche growth and plasma expansion; (5) plasma contraction; (6) termination of the plasma discharge; and (7) heat exchange stage. From this analysis, a critical voltage criterion for breakdown is obtained. We anticipate this finding will provide guidance for a better application of plasma discharges, especially diaphragm plasma discharges.

  11. First results with a surface conversion H ion source based on helicon wave mode-driven plasma discharge

    Energy Technology Data Exchange (ETDEWEB)

    Tarvainen, Ollie A [Los Alamos National Laboratory; Geros, Ernest [Los Alamos National Laboratory; Rouleau, Gary [Los Alamos National Laboratory; Zaugg, Thomas J [Los Alamos National Laboratory

    2008-01-01

    The currently employed converter-type negative ion source at Los Alamos Neutron Science Center (LANSCE) is based on cesium enhanced surface production of H{sup -} ion beams in a filament-driven discharge. The extracted H{sup -} beam current is limited by the achievable plasma density, which depends primarily on the electron emission current from the filaments. The emission current can be increased by increasing the filament temperature but, unfortunately, this leads not only to shorter filament lifetime but also to an increase in metal evaporation from the filament, which degrades the performance of the H{sup -} conversion surface. In order to overcome these limitations we have designed and tested a prototype of a surface conversion H{sup -} ion source, based on excitation of helicon plasma wave mode with an external antenna. The source has been operated with and without cesium injection. An H{sup -} beam current of over 12 mA has been transported through the low energy beam transport of the LANSCE ion source test stand. The results of these experiments and the effects of different source parameters on the extracted beam current are presented. The limitations of the source prototype are discussed and future improvements are proposed based on the experimental observations.

  12. Plasma diagnostics discharge parameters and chemistry

    CERN Document Server

    Auciello, Orlando

    1989-01-01

    Plasma Diagnostics, Volume 1: Discharge Parameters and Chemistry covers seven chapters on the important diagnostic techniques for plasmas and details their use in particular applications. The book discusses optical diagnostic techniques for low pressure plasmas and plasma processing; plasma diagnostics for electrical discharge light sources; as well as Langmuir probes. The text also describes the mass spectroscopy of plasmas, microwave diagnostics, paramagnetic resonance diagnostics, and diagnostics in thermal plasma processing. Electrical engineers, nuclear engineers, microwave engineers, che

  13. Plasma spark discharge reactor and durable electrode

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Young I.; Cho, Daniel J.; Fridman, Alexander; Kim, Hyoungsup

    2017-01-10

    A plasma spark discharge reactor for treating water. The plasma spark discharge reactor comprises a HV electrode with a head and ground electrode that surrounds at least a portion of the HV electrode. A passage for gas may pass through the reactor to a location proximate to the head to provide controlled formation of gas bubbles in order to facilitate the plasma spark discharge in a liquid environment.

  14. Plasma discharge self-cleaning filtration system

    Science.gov (United States)

    Cho, Young I.; Fridman, Alexander; Gutsol, Alexander F.; Yang, Yong

    2014-07-22

    The present invention is directed to a novel method for cleaning a filter surface using a plasma discharge self-cleaning filtration system. The method involves utilizing plasma discharges to induce short electric pulses of nanoseconds duration at high voltages. These electrical pulses generate strong Shockwaves that disintegrate and dislodge particulate matter located on the surface of the filter.

  15. Combustion Enhancement with a Silent Discharge Plasma

    Science.gov (United States)

    Rosocha, Louis

    2003-10-01

    It is well known that the application of an external electric field to a flame can affect its propagation speed, stability, and combustion chemistry (Lawton & Weinberg 1969). External electrodes, arc discharges, and plasma jets have been employed to allow combustible gas mixtures to operate outside their flammability limits by gas heating, injection of free radicals, and field-promoted flame stabilization (Yagodnikov & Voronetskii 1994). Other investigators have carried out experiments with silent electrical discharges applied to propagating flames (Inomata et al 1983, Kim et al 2003). These have demonstrated that the flame propagation velocity is actually decreased (combustion retarded) when a silent discharge is applied directly to the flame region, but that the flame propagation velocity is increased (combustion promoted) when a silent discharge is applied to the unburned gas mixture upstream of a flame. Two other recent works have considered the possibility of combustion enhancement in aircraft gas turbine engine combustor mixers by using a plasma-generating fuel nozzle, that employs an electric-arc or microwave plasma generator, to produce dissociated fuel or ionized fuel (Johnson et al 2001); and pulsed corona-enhanced detonation of fuel-air mixtures in jet engines (Wang et al 2003). In contrast to these prior works, we have employed a silent discharge plasma (SDP) reactor to break up large fuel molecules into smaller molecules and create free radicals or other active species in a gas stream before the fuel is mixed with an oxidizer and combusted. In experiments reported here, a cylindrical SDP reactor was used to 'activate' propane before mixing it with air and igniting the combustible gas mixture. With the plasma, the physical appearance of the flame changes and substantial changes in mass spectrometer fragmentation peaks are observed (e.g., propane fragments decrease and water and carbon dioxide increase). This indicates that the combustion process is

  16. Studying surface glow discharge for application in plasma aerodynamics

    Science.gov (United States)

    Tereshonok, D. V.

    2014-02-01

    Surface glow discharge in nitrogen between two infinite planar electrodes occurring on the same plane has been studied in the framework of a diffusion-drift model. Based on the results of numerical simulations, the plasma structure of this discharge is analyzed and the possibility of using it in plasma aerodynamics is considered.

  17. Stabilizing effect of plasma discharge on bubbling fluidized granular bed

    Science.gov (United States)

    Hu, Mao-Bin; Dang, Sai-Chao; Ma, Qiang; Xia, Wei-Dong

    2015-07-01

    Fluidized beds have been widely used for processing granular materials. In this paper, we study the effect of plasma on the fluidization behavior of a bubbling fluidized bed with an atmospheric pressure plasma discharger. Experiment results show that the bubbling fluidized bed is stabilized with the discharge of plasma. When the discharge current reaches a minimum stabilization current Cms, air bubbles in the bed will disappear and the surface fluctuation is completely suppressed. A simplified model is proposed to consider the effect of electric Coulomb force generated by the plasma. It is found that the Coulomb force will propel the particles to move towards the void area, so that the bubbling fluidized bed is stabilized with a high enough plasma discharge. Project supported by the National Natural Science Foundation of China (Grant Nos. 11035005 and 11034010).

  18. Direct current dielectric barrier assistant discharge to get homogeneous plasma in capacitive coupled discharge

    Energy Technology Data Exchange (ETDEWEB)

    Du, Yinchang, E-mail: ycdu@mail.ustc.edu.cn [Modern Physics Department, University of Science and Technology of China, Hefei, Anhui 230026 (China); Max-Planck Institute for Extraterrestrial Physics, D-85748 Garching (Germany); Li, Yangfang [Max-Planck Institute for Extraterrestrial Physics, D-85748 Garching (Germany); Cao, Jinxiang; Liu, Yu; Wang, Jian; Zheng, Zhe [Modern Physics Department, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2014-06-15

    In this paper, we propose a method to get more homogeneous plasma in the geometrically asymmetric capacitive coupled plasma (CCP) discharge. The dielectric barrier discharge (DBD) is used for the auxiliary discharge system to improve the homogeneity of the geometrically asymmetric CCP discharge. The single Langmuir probe measurement shows that the DBD can increase the electron density in the low density volume, where the DBD electrodes are mounted, when the pressure is higher than 5 Pa. By this manner, we are able to improve the homogeneity of the plasma production and increase the overall density in the target volume. At last, the finite element simulation results show that the DC bias, applied to the DBD electrodes, can increase the homogeneity of the electron density in the CCP discharge. The simulation results show a good agreement with the experiment results.

  19. Analysis of radiofrequency discharges in plasma

    Science.gov (United States)

    Kumar, Devendra; McGlynn, Sean P.

    1992-01-01

    Separation of laser optogalvanic signals in plasma into two components: (1) an ionization rate change component, and (2) a photoacoustic mediated component. This separation of components may be performed even when the two components overlap in time, by measuring time-resolved laser optogalvanic signals in an rf discharge plasma as the rf frequency is varied near the electrical resonance peak of the plasma and associated driving/detecting circuits. A novel spectrometer may be constructed to make these measurements. Such a spectrometer would be useful in better understanding and controlling such processes as plasma etching and plasma deposition.

  20. Formation of a strong electric field resulting in the excitation of microplasma discharges at the edge of a dielectric film on a metal in a plasma flow

    Science.gov (United States)

    Ivanov, V. A.; Sakharov, A. S.; Konyzhev, M. E.

    2016-06-01

    Results are presented from experimental and analytical studies of the processes resulting in the excitation of microplasma discharges (MPDs) on a metal surface partially covered with a thin dielectric film under the action of an external plasma flow in vacuum. It is shown experimentally that MPDs are excited at the interface between the open metal surface and the region covered by the dielectric film. The probability of MPD excitation is investigated as a function of the thickness of the dielectric film deposited on the metal. It is found that, for a film thickness of 1 μm, the probability of MPD excitation is close to unity. As the film thickness decreases below ~10 nm or increases above ~10 μm, the probability of MPD excitation is reduced by more than two orders of magnitude. A two-dimensional kinetic numerical code is developed that allows one to model the processes of Debye sheath formation and generation of a strong electric field near the edge of a finite-thickness dielectric film on a metal surface in a plasma flow for different configurations of the film edge. It is shown that the maximum value of the tangential component of the electric field is reached at the film edge and amounts to E max ≈ |φ0|/2 d (where φ0 qualitative idea about the mechanism of the formation of a strong electric field resulting in the excitation of MPDs at the edge of a dielectric film on a metal surface in a plasma flow and agree with experimental data.

  1. Benzene conversion by manganese dioxide assisted silent discharge plasma

    Institute of Scientific and Technical Information of China (English)

    LU Bin; JI Min; YU Xin; FENG Tao; YAO Shuiliang

    2007-01-01

    Non-thermal plasma technologies have shown their promising potential specially for the low concentration of volatile organic compound control in indoor air in recent years.But it is also high energy consuming.So,to improve the energy efficiency,adding catalysts which enhance the plasma chemical reactions to plasma reactors may be a good selection.Therefore,in this study the manganese dioxide assisted silent discharge plasma was developed for benzene conversion at a relatively high energy efficiency.The results show that MnO2 could promote complete oxidation of benzene with O2 and O3 produced in the plasma discharge zone.The energy efficiency of benzene conversion with MnO2 was two folds as much as that without catalysts.It was also found that the site of MnO2 in the reactor and the energy density had effects on benzene conversion.While the energy density was lower than 48 J/L,benzene conversion decreased with the increase in the distance between MnO2 bed and the plasma discharge zone.Whereas when the energy density was higher than 104 J/L,benzene conversion had an optimal value that was governed by the distance between MnO2 bed and the plasma discharge zone.The mechanism of benzene oxidation in plasma discharges and over MnO2 is discussed in detail.

  2. Sheet Plasma Produced by Hollow Cathode Discharge

    Institute of Scientific and Technical Information of China (English)

    张龙; 张厚先; 杨宣宗; 冯春华; 乔宾; 王龙

    2003-01-01

    A sheet plasma is produced by a hollow cathode discharge under an axial magnetic field.The plasma is about 40cm in length,4 cm in width and 1cm in thickness.The electron density is about 108cm-3.The hollow cathode is made to be shallow with a large opening,which is different from the ordinary deep hollow cathode.A Langmuir probe is used to detect the plasma.The electron density and the spatial distribution of the plasma change when voltage,pressure and the magnetic field vary.A peak and a data fluctuation at about 200 G-300 G are observed in the variation of electron density(or thickness of the sheet plasma)with the magnetic field.Our work will be helpful in characterizing the sheet plasma and will make the production of dense sheet plasma more controllable.

  3. Plasma Acceleration from RF Discharge in Dielectric Capillary

    Energy Technology Data Exchange (ETDEWEB)

    A. Dunaevsky; Y. Raitses; N. J. Fisch

    2005-08-09

    Plasma acceleration from rf discharge in dielectric capillary was demonstrated. Observed plasma flow had ion energies of approximately 100 eV and electron energies of approximately 20 eV. The discharge was powered by a MHz-range rf generator and fed by Ar. Experimental results indicate possible validity of assumptions about formation of a potential difference at the open end of the capillary and presence of hot electron fraction in the capillary discharge. Simplicity and small dimensions of the source are attractive for micro-propulsion applications.

  4. Underwater plasma discharge and its water treatment applications

    Science.gov (United States)

    Ma, Sukhwal; Huh, Jin Young; Kim, Kangil; Hong, Yong Cheol; National Fusion Research Institute Team; Chonbuk National University Team; Kwangwoon University Team; NPAC Team

    2016-09-01

    In recent, the quality of water has been exacerbated by the influx of wastewater and water pollutants. There have been frequent occurrences of water blooms due to the eutrophication of river. Therefore, the needs for water treatment are increased through effective and environment-friendly method. In this work, we propose the plasma system to overcome the problems mentioned above using underwater discharge plasma. The underwater discharges are generated by capillary electrode, and have the advantages of low cost, high efficiency and eco-friendly processing. The proposed technologies can be suitable for eliminating cyanobacteria, decreasing the concentration of oil dissolved in water, and purifying wastewater. Cyanobacteria is killed directly by the underwater discharge and water-dissolved oil and heavy-metal wastewater are purified by coagulation effect, which may result from the chemical reactions of underwater plasma. Consequently, these technologies using underwater discharge can be alternative methods to replace the existing technologies.

  5. Improvement on Diamond Nucleation Treated by Pulsed Arc Discharge Plasma

    Institute of Scientific and Technical Information of China (English)

    马志斌; 万军; 汪建华; 张文文

    2004-01-01

    A technique of improvement on diamond nucleation based on pulsed arc discharge plasma at atmospheric pressure was developed. The pulsed arc discharge was induced respectively by nitrogen, argon and methanol gas. After the arc plasma pretreatment, a nucleation density higher than 1010 cm-2 may be obtained subsequently in chemical vapor deposition (CVD) on a mirror-polished silicon substrate without any other mechanical treatment. The effects of the arc discharge plasma on the diamond nucleation were investigated by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR) and Raman spectroscopy. The enhancement of nucleation is postulated to be a result of the formation of carbonlike phase materials or nitrogenation on the substrate surface without surface defect produced by arc discharge.

  6. Flush-mounted probe diagnostics for argon glow discharge plasma

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Liang, E-mail: xld02345@mail.ustc.edu.cn; Cao, Jinxiang; Liu, Yu; Wang, Jian; Du, Yinchang; Zheng, Zhe; Zhang, Xiao; Wang, Pi [Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Zhang, Jin; Li, Xiao; Qin, Yongqiang; Zhao, Liang [Science and Technology on Space Physics Laboratory, Beijing 100076 (China)

    2014-09-15

    A comparison is made between plasma parameters measured by a flush-mounted probe (FP) and a cylindrical probe (CP) in argon glow discharge plasma. Parameters compared include the space potential, the plasma density, and the effective electron temperature. It is found that the ion density determined by the FP agrees well with the electron density determined by the CP in the quasi-neutral plasma to better than 10%. Moreover, the space potential and effective electron temperature calculated from electron energy distribution function measured by the FP is consistent with that measured by the CP over the operated discharge current and pressure ranges. These results present the FP can be used as a reliable diagnostic tool in the stable laboratory plasma and also be anticipated to be applied in other complicated plasmas, such as tokamaks, the region of boundary-layer, and so on.

  7. Analytical calculations of anode plasma position in high-voltage discharge range in case of auxiliary discharge firing

    OpenAIRE

    Melnyk, Igor V.; Tugay, S. B.

    2012-01-01

    We consider the mathematical model of triode high-voltage glow discharge range in case of auxiliary discharge firing. On a basis of analysis of elementary processes of charged particles interaction in a discharge range we obtain analytical relation, which allows to obtain the anode plasma position with regard to the cathode. Obtained results can be used for analysis of analysis of energy balance in a discharge range and self-maintained electron-ion optics of high voltage glow discharge electr...

  8. Hybrid Modeling of Plasma Discharges

    Science.gov (United States)

    2010-04-01

    kinetics. The same cellular structure resulting from a highly exothermic detonation wave can be observed in an endothermic system. In a detonation system...length is 2 cm (dashed line in bottom figure). Note that a better agreement could be obtained with a better definition of the induction length...node position. The weighting function evaluated at the node position itself is of course 1; after using the definition of the centroid, (8-13

  9. Volume Diffuse Dielectric Barrier Discharge Plasma Produced by Nanosecond High Voltage Pulse in Airflow

    Institute of Scientific and Technical Information of China (English)

    QI Haicheng; GAO Wei; FAN Zhihui; LIU Yidi; REN Chunsheng

    2016-01-01

    Volume diffuse dielectric barrier discharge (DBD) plasma is produced in subsonic airflow by nanosecond high-voltage pulse power supply with a plate-to-plate discharge cell at 6 mm air gap length.The discharge images,optical emission spectra (OES),the applied voltage and current waveforms of the discharge at the changed airflow rates are obtained.When airflow rate is increased,the transition of the discharge mode and the variations of discharge intensity,breakdown characteristics and the temperature of the discharge plasma are investigated.The results show that the discharge becomes more diffuse,discharge intensity is decreased accompanied by the increased breakdown voltage and time lag,and the temperature of the discharge plasma reduces when airflow of small vclocity is introduced into the discharge gap.These phenomena are because that the airflow changes the spatial distribution of the heat and the space charge in the discharge gap.

  10. Volume Diffuse Dielectric Barrier Discharge Plasma Produced by Nanosecond High Voltage Pulse in Airflow

    Science.gov (United States)

    Qi, Haicheng; Gao, Wei; Fan, Zhihui; Liu, Yidi; Ren, Chunsheng

    2016-05-01

    Volume diffuse dielectric barrier discharge (DBD) plasma is produced in subsonic airflow by nanosecond high-voltage pulse power supply with a plate-to-plate discharge cell at 6 mm air gap length. The discharge images, optical emission spectra (OES), the applied voltage and current waveforms of the discharge at the changed airflow rates are obtained. When airflow rate is increased, the transition of the discharge mode and the variations of discharge intensity, breakdown characteristics and the temperature of the discharge plasma are investigated. The results show that the discharge becomes more diffuse, discharge intensity is decreased accompanied by the increased breakdown voltage and time lag, and the temperature of the discharge plasma reduces when airflow of small velocity is introduced into the discharge gap. These phenomena are because that the airflow changes the spatial distribution of the heat and the space charge in the discharge gap. supported by National Natural Science Foundation of China (No. 51437002)

  11. Ignition Features of Plasma-Beam Discharge in Gas-Discharge Electron Gun Operation

    Directory of Open Access Journals (Sweden)

    Valery A. Tutyk

    2013-01-01

    Full Text Available The current paper presents the results of experimental researches to determine the mode features of plasma-beam discharge (PBD generation by an electron beam injected by a low-vacuum gasdischarge electron gun (LGEG with the cold cathode and hollow anode on the basis of the high-voltage glow discharge and in the range of helium pressure of P ? 10 ÷ 130 Pa. The PBD boundaries and their dependences on parameters of an electron beam are found. The influence of PBD on parameters of low-vacuum gas-discharge electron gun is revealed. It causes an avalanche increase of electron beam current and burning of plasma-beam discharge in the whole space of the vacuum chamber volume and generation of electromagnetic radiation is revealed. Achieved results will be used for implementation of various vacuum technologies in the medium of reaction gas and generated electromagnetic radiation.

  12. High-frequency underwater plasma discharge application in antibacterial activity

    Science.gov (United States)

    Ahmed, M. W.; Choi, S.; Lyakhov, K.; Shaislamov, U.; Mongre, R. K.; Jeong, D. K.; Suresh, R.; Lee, H. J.

    2017-03-01

    Plasma discharge is a novel disinfection and effectual inactivation approach to treat microorganisms in aqueous systems. Inactivation of Gram-negative Escherichia coli ( E. coli) by generating high-frequency, high-voltage, oxygen (O2) injected and hydrogen peroxide (H2O2) added discharge in water was achieved. The effect of H2O2 dose and oxygen injection rate on electrical characteristics of discharge and E. coli disinfection has been reported. Microbial log reduction dependent on H2O2 addition with O2 injection was observed. The time variation of the inactivation efficiency quantified by the log reduction of the initial E. coli population on the basis of optical density measurement was reported. The analysis of emission spectrum recorded after discharge occurrence illustrated the formation of oxidant species (OH•, H, and O). Interestingly, the results demonstrated that O2 injected and H2O2 added, underwater plasma discharge had fabulous impact on the E. coli sterilization. The oxygen injection notably reduced the voltage needed for generating breakdown in flowing water and escalated the power of discharge pulses. No impact of hydrogen peroxide addition on breakdown voltage was observed. A significant role of oxidant species in bacterial inactivation also has been identified. Furthermore the E. coli survivability in plasma treated water with oxygen injection and hydrogen peroxide addition drastically reduced to zero. The time course study also showed that the retardant effect on E. coli colony multiplication in plasma treated water was favorable, observed after long time. High-frequency underwater plasma discharge based biological applications is technically relevant and would act as baseline data for the development of novel antibacterial processing strategies.

  13. High-frequency underwater plasma discharge application in antibacterial activity

    Science.gov (United States)

    Ahmed, M. W.; Choi, S.; Lyakhov, K.; Shaislamov, U.; Mongre, R. K.; Jeong, D. K.; Suresh, R.; Lee, H. J.

    2017-03-01

    Plasma discharge is a novel disinfection and effectual inactivation approach to treat microorganisms in aqueous systems. Inactivation of Gram-negative Escherichia coli (E. coli) by generating high-frequency, high-voltage, oxygen (O2) injected and hydrogen peroxide (H2O2) added discharge in water was achieved. The effect of H2O2 dose and oxygen injection rate on electrical characteristics of discharge and E. coli disinfection has been reported. Microbial log reduction dependent on H2O2 addition with O2 injection was observed. The time variation of the inactivation efficiency quantified by the log reduction of the initial E. coli population on the basis of optical density measurement was reported. The analysis of emission spectrum recorded after discharge occurrence illustrated the formation of oxidant species (OH•, H, and O). Interestingly, the results demonstrated that O2 injected and H2O2 added, underwater plasma discharge had fabulous impact on the E. coli sterilization. The oxygen injection notably reduced the voltage needed for generating breakdown in flowing water and escalated the power of discharge pulses. No impact of hydrogen peroxide addition on breakdown voltage was observed. A significant role of oxidant species in bacterial inactivation also has been identified. Furthermore the E. coli survivability in plasma treated water with oxygen injection and hydrogen peroxide addition drastically reduced to zero. The time course study also showed that the retardant effect on E. coli colony multiplication in plasma treated water was favorable, observed after long time. High-frequency underwater plasma discharge based biological applications is technically relevant and would act as baseline data for the development of novel antibacterial processing strategies.

  14. High-frequency underwater plasma discharge application in antibacterial activity

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, M. W.; Choi, S.; Lyakhov, K.; Shaislamov, U. [Jeju National University, Department of Nuclear and Energy Engineering (Korea, Republic of); Mongre, R. K.; Jeong, D. K. [Jeju National University, Faculty of Biotechnology (Korea, Republic of); Suresh, R.; Lee, H. J., E-mail: hjlee@jejunu.ac.kr [Jeju National University, Department of Nuclear and Energy Engineering (Korea, Republic of)

    2017-03-15

    Plasma discharge is a novel disinfection and effectual inactivation approach to treat microorganisms in aqueous systems. Inactivation of Gram-negative Escherichia coli (E. coli) by generating high-frequency, high-voltage, oxygen (O{sub 2}) injected and hydrogen peroxide (H{sub 2}O{sub 2}) added discharge in water was achieved. The effect of H{sub 2}O{sub 2} dose and oxygen injection rate on electrical characteristics of discharge and E. coli disinfection has been reported. Microbial log reduction dependent on H{sub 2}O{sub 2} addition with O{sub 2} injection was observed. The time variation of the inactivation efficiency quantified by the log reduction of the initial E. coli population on the basis of optical density measurement was reported. The analysis of emission spectrum recorded after discharge occurrence illustrated the formation of oxidant species (OH{sup •}, H, and O). Interestingly, the results demonstrated that O{sub 2} injected and H{sub 2}O{sub 2} added, underwater plasma discharge had fabulous impact on the E. coli sterilization. The oxygen injection notably reduced the voltage needed for generating breakdown in flowing water and escalated the power of discharge pulses. No impact of hydrogen peroxide addition on breakdown voltage was observed. A significant role of oxidant species in bacterial inactivation also has been identified. Furthermore the E. coli survivability in plasma treated water with oxygen injection and hydrogen peroxide addition drastically reduced to zero. The time course study also showed that the retardant effect on E. coli colony multiplication in plasma treated water was favorable, observed after long time. High-frequency underwater plasma discharge based biological applications is technically relevant and would act as baseline data for the development of novel antibacterial processing strategies.

  15. Destruction of Bacterial Biofilms Using Gas Discharge Plasma

    Science.gov (United States)

    Abramzon, Nina

    2005-03-01

    Biofilms are bacterial communities embedded in an exopolysaccharidic matrix with a complex architectural structure. Bacteria in biofilms show different properties from those in free life thus, conventional methods of killing bacteria are often ineffective with biofilms. The use of plasmas potentially offers an alternative to conventional sterilization methods since plasmas contain a mixture of charged particles, chemically reactive species, and UV radiation. 4 and 7 day-old biofilms were produced using two bacterial species: Rhizobium gallicum and Chromobacterium violaceum. Gas discharge plasma was produced by using an AtomfloTM reactor (Surfx Technologies) and bacterial biofilms were exposed to it for different periods of time. Our results show that a 10-minute plasma treatment was able to kill 100% of the cells in most cases. Optical emission spectroscopy was used to study plasma composition which is then correlated with the effectiveness of killing. These results indicate the potentiality of plasma as an alternative sterilization method. Supported by CSuperb.

  16. Plasma production by means of discharge in a spherical cavity

    NARCIS (Netherlands)

    Antsiferov, P. S.; Dorokhin, L. A.; Koshelev, K. N.

    2010-01-01

    The work is devoted to the study of plasma, appearing as a result of cumulation of shock wave with form close to spherical. The shock wave was obtained by triggering of fast discharge (dI/dt about 10(12) A/s) on inner surface of cavity, made from insulator. Spherical cavity with radius 4.5 mm was fi

  17. Sterilization of Turmeric by Atmospheric Pressure Dielectric Barrier Discharge Plasma

    Science.gov (United States)

    Setareh, Salarieh; Davoud, Dorranian

    2013-11-01

    In this study atmospheric pressure dielectric barrier discharge (DBD) plasma has been employed for sterilizing dry turmeric powders. A 6 kV, 6 kHz frequency generator was used to generate plasma with Ar, Ar/O2, He, and He/O2 gases between the 5 mm gap of two quartz covered electrodes. The complete sterilization time of samples due to plasma treatment was measured. The most important contaminant of turmeric is bacillus subtilis. The results show that the shortest sterilization time of 15 min is achieved by exposing the samples to Ar/O2 plasma. Survival curves of samples are exponential functions of time and the addition of oxygen to plasma leads to a significant increase of the absolute value of time constant of the curves. Magnitudes of protein and DNA in treated samples were increased to a similar value for all samples. Taste, color, and solubility of samples were not changed after the plasma treatment.

  18. Plasma environment during hot cathode direct current discharge plasma chemical vapor deposition of diamond films

    Institute of Scientific and Technical Information of China (English)

    朱晓东; 詹如娟; 周海洋; 胡敏; 温晓辉; 周贵恩; 李凡庆

    1999-01-01

    The plasma characteristics have been investigated in situ by using optical emission spectroscopy (OES) and the Langmuir probe during hot cathode direct current discharge plasma chemical vapor deposition of diamond films. The changes of atomic H and CH radical in the ground state have been calculated quantitatively according to the results of OES and the Langmuir probe measurement as discharge current density varied. It is shown that atomic H and CH radicals both in the ground state and in the excited state increase with the enhancement of the discharge current density in the plasma. The electron density and CH emission intensity increase linearly with the enhancement of discharge current densities. The generation of different carbon-containing radicals is related to the elevation of electron temperature. Combining the growth process of diamond films and the diagnostic results, it is shown that atomic H in the excited state may improve the diamond growth efficiently, and the increase of electron temperat

  19. Electrical and spectroscopic characterization of a surgical argon plasma discharge

    Science.gov (United States)

    Keller, Sandra; Bibinov, Nikita; Neugebauer, Alexander; Awakowicz, Peter

    2013-01-01

    For electrosurgical procedures, the argon plasma coagulation (APC) discharge is a well-established atmospheric-pressure plasma tool for thermal haemostasis and devitalization of biological tissue. To characterize this plasma source, voltage-current measurements, microphotography, optical emission spectroscopy and numerical simulation are applied. Two discharge modes are established during the operation of the APC plasma source. A short transient spark discharge is ignited within the positive half period of the applied high voltage after a streamer channel connects the APC probe and the counter-electrode. During the second phase, which continues under negative high voltage, a glow discharge is stabilized in the plasma channel.

  20. Research on the Plasma Anemometer Based on AC Glow Discharge

    Directory of Open Access Journals (Sweden)

    Bing Yu

    2017-01-01

    Full Text Available A new plasma anemometer based on AC glow discharge is designed in this article. Firstly, theoretical analysis of plasma anemometer working principle is introduced to prove the feasibility of the experimental measurement method. Then the experiments are carried out to study the effects of different parameters on the static discharge characteristics of the plasma anemometer system, by which the system optimization methods are obtained. Finally, several groups of appropriate parameters are selected to build the plasma anemometer system based on resistance capacitance coupling negative feedback AC glow discharge, and different airflow speeds are applied to obtain the achievable velocity measurement range. The results show that there is a linear relationship between airflow velocity and discharge current in an allowable error range, which can be applied for airflow velocity measurement. Negative feedback coupling module, which is composed of the coupling resistance and the coupling capacitance, has good effects on improving the system stability. The measurement range of the airflow velocity is significantly increased when the electrode gap is 3 mm, coupling resistance is 470 Ω, and coupling capacitance is 220 pF.

  1. Electrohydrodynamic force in dielectric barrier discharge plasma actuators

    Energy Technology Data Exchange (ETDEWEB)

    Boeuf, J P; Lagmich, Y; Unfer, Th; Callegari, Th; Pitchford, L C [CPAT-CNRS, Universite Paul Sabatier, 118 Route de Narbonne, Toulouse 31062 (France)

    2007-02-07

    Surface dielectric barrier discharges (DBDs) have been proposed as actuators for flow control. In this paper we discuss the basic mechanisms responsible for the electrohydrodynamic (EHD) force exerted by the discharge on the gas molecules. A two-dimensional fluid model of the DBD is used to describe the plasma dynamics, to understand the basic physics associated with the EHD force and to give some quantitative estimation of the force under simplified conditions. The results show that for ramp or sinusoidal voltage waveforms, the discharge consists of large amplitude short current pulses during which a filamentary plasma spreads along the surface, separated in time by long duration, low current discharge phases of a Townsend or corona type. The contribution of the low current phases to the total force exerted by the discharge on the gas is dominant because their duration is much longer than that of the current pulses and because the force takes place in a much larger volume. A description of the different discharge regimes and a parametric study of the EHD force as a function of voltage rise time and dielectric thickness is presented.

  2. The Main Plasma Chemical Process of Nitric Oxide Production by Arc Discharge%The Main Plasma Chemical Process of Nitric Oxide Production by Arc Discharge

    Institute of Scientific and Technical Information of China (English)

    杨旗; 胡辉; 陈卫鹏; 许杰; 张锦丽; 吴双

    2011-01-01

    By adopting the optical multi-channel analyzer combined with fourier transform infrared (FTIR) spectrometer, the dominant free radicals and products generated by arc discharge were measured and studied, and the main plasma chemical reaction process in the nitric oxide production by arc discharge was identified. Plasma chemical kinetic curves of O, O2, N2, N and NO were simulated by using CHEMKIN and MATLAB. The results show that the main plasma chemical reaction process of nitric oxide production by arc discharge is a replacement reaction between O and N2, where NO can be generated instantaneously when discharging reaches stable.

  3. Combustion Enhancement Using a Silent Discharge Plasma Reactor

    Science.gov (United States)

    Rosocha, Louis; Platts, David; Coates, Don; Stange, Sy

    2003-10-01

    Electric fields affect flame propagation speed, stability, and combustion chemistry. External electrodes, arc discharges, and plasma jets have been used to combust gas mixtures outside their flammability limits. Experiments with silent electrical discharges (SEDs) and propagating flames have shown that flame propagation velocity is actually decreased (combustion retarded) when an SED is applied directly to the flame region, but velocity is increased (combustion promoted) when applied to the unburned gas mixture upstream of a flame. More recent work has proposed electric arc/microwave-driven plasma-generating fuel nozzles to produce dissociated fuel or ionized fuel for aircraft gas turbine engine combustor mixers. In contrast to prior works, we have used a silent discharge plasma (SDP) reactor to break up large fuel molecules into smaller molecules and create free radicals/active species in a gas stream before the fuel is mixed with an oxidizer and combusted. A cylindrical SDP reactor was used to 'activate' propane before mixing it with air and igniting the combustible gas mixture. With the plasma, the physical appearance of the flame changes and substantial changes in mass spectrometer fragmentation peaks for fuel and combustion products are observed (i.e., combustion is enhanced). Results of changes in the degree of combustion will be discussed in terms of variations in the plasma specific energy.

  4. Characterization of a Dielectric Barrier Plasma Gun Discharging at Atmospheric Pressure

    Institute of Scientific and Technical Information of China (English)

    ZHANG Guang-Qiu; GE Yuan-Jing; ZHANG Yue-Fei; CHEN Guang-Liang

    2004-01-01

    @@ We develop a plasma gun based on dielectric barrier discharge and working at atmospheric pressure. A theoretical model to predict the gun discharge voltage is built, which is in agreement with the experimental results. After investigating the characterization of discharging gun and utilizing it for polymerization, we find that the gun can be used as a source to generate a stable uniform plasma for different plasma-processing technologies.

  5. Coal Liquefaction by Using Dielectric Barrier Discharge Plasma

    Science.gov (United States)

    Wang, Qiuying; Wu, Peng; Gu, Fan

    2013-07-01

    An innovative method for coal liquefaction by using dielectric barrier discharge (DBD) plasma in a short reaction time was developed. Using tetralin as the reaction medium, DBD plasma as the energy source, and a reaction time of 10 min at 140°C, up to 10% of coal was converted to liquid material. The results showed the feasibility of coal's liquefaction by DBD plasma under relatively moderate conditions. Simultaneously, it was clarified that the effect of DBD plasma treatment was opposed to the thermal effect of heating. An acid plasma sheath could be formed on the coal powder surface in DBD conditions, liquefied reactions could be carried out in the absence of inorganic acid, and the products were nearly neutral and with low causticity.

  6. Glow Discharge Plasma Nitriding of AISI 304 Stainless Steel

    Institute of Scientific and Technical Information of China (English)

    A.QAYYUM; M.A.NAVEED; S.ZEB; G.MURTAZA; M.ZAKAULLAH

    2007-01-01

    Glow discharge plasma nitriding of AISI 304 austenitic stainless steel has been carried out for different processing time under optimum discharge conditions established by spectroscopic analysis.The treated samples were analysed by X-ray diffraction(XRD)to explore the changes induced in the crystallographic structure.The XRD pattern confirmed the formation of an expanded austenite phase(γN)owing to incorporation of nitrogen as an interstitial solid solution in the iron lattice.A Vickers microhardness tester was used to evaluate the surface hardness as a function of indentation depth(μm).The results showed clear evidence of surface changes with substantial increase in surface hardness.

  7. Autonomous Method and System for Minimizing the Magnitude of Plasma Discharge Current Oscillations in a Hall Effect Plasma Device

    Science.gov (United States)

    Hruby, Vladimir (Inventor); Demmons, Nathaniel (Inventor); Ehrbar, Eric (Inventor); Pote, Bruce (Inventor); Rosenblad, Nathan (Inventor)

    2014-01-01

    An autonomous method for minimizing the magnitude of plasma discharge current oscillations in a Hall effect plasma device includes iteratively measuring plasma discharge current oscillations of the plasma device and iteratively adjusting the magnet current delivered to the plasma device in response to measured plasma discharge current oscillations to reduce the magnitude of the plasma discharge current oscillations.

  8. Review of relaxation oscillations in plasma processing discharges

    Institute of Scientific and Technical Information of China (English)

    Zhou Zhu-Wen; M.A.Lieberman; Sungjin Kim

    2007-01-01

    Relaxation oscillations due to plasma instabilities at frequencies ranging from a few Hz to tens of kHz have been observed in various types of plasma processing discharges.Relaxation oscillations have been observed in electropositive capacitive discharges between a powered anode and a metallic chamber whose periphery iS grounded through a slot with dielectric spacers.The oscillations of time-varying optical emission from the main discharge chamber show,for example,a high-frequency (~40 kHz) relaxation oscillation at 13.33Pa,with an absorbed power being nearly the peripheral breakdown power,and a low-frequency (~3 Hz) oscillation,with an even higher absorbed power.The high-frequency oscillation is found to ignite plasma in the slot,but usually not in the peripheral chamber.The kilohertz oscillations are modelled using an electromagnetic model of the slot impedance,coupled to a circuit analysis of the system including the matching network.The model results are in general agreement with the experimental observations,and indicate a variety of behaviours dependent on the matching conditions.In low-pressure inductive discharges,oscillations appear in the transition between low-density capacitively driven and high-density inductively driven discharges when attaching gases such as SF6 and Ar/SF6 mixtures are used.Oscillations of charged particles,plasma potential,and light,at frequencies ranging from a few Hz to tens of kHz,are seen for gas pressures between 0.133 Pa and 13.33 Pa and discharge powers in a range of 75-1200 W.The region of instability increases as the plasma becomes more electronegative,and the frequency of plasma oscillation increases as the power,pressure,and gas flow rate increase.A volume-averaged (global) model of the kilohertz instability has been developed;the results obtained from the model agree well with the experimental observations.

  9. Particle based plasma simulation for an ion engine discharge chamber

    Science.gov (United States)

    Mahalingam, Sudhakar

    Design of the next generation of ion engines can benefit from detailed computer simulations of the plasma in the discharge chamber. In this work a complete particle based approach has been taken to model the discharge chamber plasma. This is the first time that simplifying continuum assumptions on the particle motion have not been made in a discharge chamber model. Because of the long mean free paths of the particles in the discharge chamber continuum models are questionable. The PIC-MCC model developed in this work tracks following particles: neutrals, singly charged ions, doubly charged ions, secondary electrons, and primary electrons. The trajectories of these particles are determined using the Newton-Lorentz's equation of motion including the effects of magnetic and electric fields. Particle collisions are determined using an MCC statistical technique. A large number of collision processes and particle wall interactions are included in the model. The magnetic fields produced by the permanent magnets are determined using Maxwell's equations. The electric fields are determined using an approximate input electric field coupled with a dynamic determination of the electric fields caused by the charged particles. In this work inclusion of the dynamic electric field calculation is made possible by using an inflated plasma permittivity value in the Poisson solver. This allows dynamic electric field calculation with minimal computational requirements in terms of both computer memory and run time. In addition, a number of other numerical procedures such as parallel processing have been implemented to shorten the computational time. The primary results are those modeling the discharge chamber of NASA's NSTAR ion engine at its full operating power. Convergence of numerical results such as total number of particles inside the discharge chamber, average energy of the plasma particles, discharge current, beam current and beam efficiency are obtained. Steady state results for

  10. ORAL ISSUE OF THE JOURNAL "USPEKHI FIZICHESKIKH NAUK": Modeling of gas discharge plasma

    Science.gov (United States)

    Smirnov, Boris M.

    2009-06-01

    The condition for the self-maintenance of a gas discharge plasma (GDP) is derived from its ionization balance expressed in the Townsend form and may be used as a definition of a gas discharge plasma in its simplest form. The simple example of a gas discharge plasma in the positive column of a cylindrical discharge tube allows demonstrating a wide variety of possible GDP regimes, revealing a contradiction between simple models used to explain gas discharge regimes and the large number of real processes responsible for the self-maintenance of GDP. The variety of GDP processes also results in a stepwise change of plasma parameters and developing some instabilities as the voltage or discharge current is varied. As a consequence, new forms and new applications of gas discharge arise as technology progresses.

  11. Electrode microwave discharge: Areas of application and recent results of discharge physics

    Science.gov (United States)

    Lebedev, Yu A.; Epstein, I. L.; Tatarinov, A. V.; Shakhatov, V. A.

    2010-01-01

    The first paper on the electrode microwave discharge (EMD) appeared in 1996. Presently many problems of EMD physics and applications have already been solved. Several examples of EMD application are discussed: diamond growth, deposition of CNx films and nanotubes, deposition of metal films (Cu, Al), deposition of TiN and TiO2 films, generation of O2(a1Δ), and EMD as a plasma cathode. Results of EMD experiments and modeling give rise to the assumption that an EMD consists of a self-sustained domain (near-electrode plasma region with overcritical plasma density) which is surrounded by a region of a non-self-sustained discharge (ball shaped region with undercritical plasma density). We assumed that the layer of charge separation and of induced electrostatic field originated at the outer EMD boundary was one of the reasons for the abrupt decrease of the plasma density which leads to the formation of a compact plasma structure. Recent modeling results of the strongly nonuniform electrode microwave plasma based on a quasi static, 1D spherically symmetric model showed that such a layer can be generated at the point where a sudden increase of the total ionization rate takes place.

  12. Properties Influencing Plasma Discharges in Packed Bed Reactors

    Science.gov (United States)

    Kruszelnicki, Juliusz; Engeling, Kenneth W.; Foster, John E.; Kushner, Mark J.

    2016-09-01

    Atmospheric pressure dielectric barrier discharges (DBDs) sustained in packed bed reactors (PBRs) are being investigated for CO2 removal and conversion of waste gases into higher value compounds. We report on results of a computational investigation of PBR-DBD properties using the plasma hydrodynamics simulator nonPDPSIM with a comparison to experiments. Dielectric beads (rods in 2D) were inserted between two coplanar electrodes, 1 cm apart filled by humid air. A step-pulse of -30 kV was applied to the top electrode. Material properties of the beads (dielectric constant, secondary emission coefficient) and gas properties (photoionization and photo-absorption cross-sections, temperature) were varied. We found that photoionization plays a critical role in the propagation of the discharge through the PBR, as it serves to seed charges in regions of high electric field. Increasing rates of photo-ionization enable increases in the discharge propagation velocity, ionization rates and production of radicals. A transition between DBD-like and arc-like discharges occurs as the radiation mean free path decreases. Increasing the dielectric constant of the beads increased electric fields in the gas, which translated to increased discharge propagation velocity and charge density until ɛ/ɛ0 100. Secondary electron emission coefficient and gas temperature have minimal impacts on the discharge propagation though the latter did affect the production of reactive species. Work supported by US DOE Office of Fusion Energy Science and the National Science Foundation.

  13. Influence of Plasma Temperature on the Concentration of NO Produced by Pulsed Arc Discharge

    Institute of Scientific and Technical Information of China (English)

    胡辉; 陈卫鹏; 张锦丽; 陆僖; 何俊佳

    2012-01-01

    This study conducted experiments on producing inhaled medical nitric oxide (iNO) by pulsed arc discharge in dry and clean air under different discharge current. The concentration of NO and NO2 produced by air discharge, as well as the change of the ratio of NO2/NO under different discharge current were investigated. Through the analysis of plasma emission spectrum, the relationship between discharge current and arc plasma temperature was studied. The results indicate that, as discharge current increases, the arc plasma temperature increases, which then leads to the increase of NO concentration, the decrease of NO2 concentration, and the rapid decrease of the ratio of NO2/NO. When the plasma temperature is 9000 K, the ratio of NO2/NO is approximately 60%, while when the plasma temperature varies between 10550 K and 11300 K, the NO2/NO ratio is within the range of 4.2% to 4.6%.

  14. Simulation Tool for Dielectric Barrier Discharge Plasma Actuators

    Science.gov (United States)

    Likhanskii, Alexander

    2014-01-01

    Traditional approaches for active flow separation control using dielectric barrier discharge (DBD) plasma actuators are limited to relatively low speed flows and atmospheric conditions. This results in low feasibility of the DBDs for aerospace applications. For active flow control at turbine blades, fixed wings, and rotary wings and on hypersonic vehicles, DBD plasma actuators must perform at a wide range of conditions, including rarified flows and combustion mixtures. An efficient, comprehensive, physically based DBD simulation tool can optimize DBD plasma actuators for different operation conditions. Researchers are developing a DBD plasma actuator simulation tool for a wide range of ambient gas pressures. The tool will treat DBD using either kinetic, fluid, or hybrid models, depending on the DBD operational condition.

  15. Manufacturing of Dielectric Barrier Discharge Plasma Actuator for Degradation Resistance

    Science.gov (United States)

    Houser, Nicole M.

    The performance and broader application of dielectric barrier discharge (DBD) plasma actuators are restricted by the manufacturing methods currently employed. In the current work, two methodologies are proposed to build robust plasma actuators for active flow control; a protective silicone oil (PDMS) treatment for hand-cut and laid tape-based actuators and a microfabrication technique for glass-based devices. The microfabrication process, through which thin film electrodes are precisely deposited onto plasma-resistant glass substrates, is presented in detail. The resulting glass-based devices are characterized with respect to electrical properties and output for various operating conditions. The longevity of microfabricated devices is compared against silicone-treated and untreated hand-made devices of comparable geometries over 60 hours of continuous operation. Both tungsten and copper electrodes are considered for microfabricated devices. Human health effects are also considered in an electromagnetic field study of the area surrounding a live plasma actuator for various operating conditions.

  16. Ethanol reforming in non-equilibrium plasma of glow discharge

    CERN Document Server

    Levko, D

    2012-01-01

    The results of a detailed kinetic study of the main plasma chemical processes in non-equilibrium ethanol/argon plasma are presented. It is shown that at the beginning of the discharge the molecular hydrogen is mainly generated in the reaction of ethanol H-abstraction. Later hydrogen is formed from active H, CH2OH and CH3CHOH and formaldehyde. Comparison with experimental data has shown that the used kinetic mechanism predicts well the concentrations of main species at the reactor outlet.

  17. "Super-acceleration" of ions in a stationary plasma discharge

    Science.gov (United States)

    Bardakov, Vladimir; Ivanov, Sergey; Kazantsev, Alexander; Strokin, Nikolay; Stupin, Aleksey

    2016-10-01

    We report on the detection of the acceleration effect of the bulk of ions in a stationary plasma E × B discharge to energies exceeding considerably the value equivalent to the discharge voltage. We determined the conditions necessary for the generation of high-energy ions, and ascertained the influence exerted on the value of the ion energies by pressure (flow rate) and the kind of plasma-producing gas, and by the value of discharge current. The possible acceleration mechanism is suggested.

  18. Design of a Microwave Assisted Discharge Inductive Plasma Accelerator

    Science.gov (United States)

    Hallock, Ashley K.; Polzin, Kurt A.

    2010-01-01

    The design and construction of a thruster that employs electrodeless plasma preionization and pulsed inductive acceleration is described. Preionization is achieved through an electron cyclotron resonance discharge that produces a weakly-ionized plasma at the face of a conical theta pinch-shaped inductive coil. The presence of the preionized plasma allows for current sheet formation at lower discharge voltages than those employed in other pulsed inductive accelerators that do not employ preionization. The location of the electron cyclotron resonance discharge is controlled through the design of the applied magnetic field in the thruster. Finite element analysis shows that there is an arrangement of permanent magnets that yields a small volume of resonant magnetic field at the coil face. Preionization in the resonant zone leads to current sheet formation at the coil face, which minimizes the initial inductance of the pulse circuit and maximizes the potential electrical efficiency of the accelerator. A magnet assembly was constructed around an inductive coil to provide structural support to the selected arrangement of neodymium magnets. Measured values of the resulting magnetic field compare favorably with the finite element model.

  19. Parameters influencing plasma column potential in a reflex discharge

    Science.gov (United States)

    Liziakin, G. D.; Gavrikov, A. V.; Murzaev, Y. A.; Usmanov, R. A.; Smirnov, V. P.

    2016-12-01

    Distribution of electrostatic potential in direct current reflex discharge plasma has been studied experimentally. Measurements have been conducted by the single floating probe method. The influence of 0-0.2 T magnetic field, 1-200 mTorr pressure, 0-2 kV discharge voltage, and electrodes geometry on plasma column electrostatic potential was investigated. The possibility for the formation of a preset potential profile required for the realization of plasma separation of spent nuclear fuel was demonstrated.

  20. An investigation of an underwater steam plasma discharge as alternative to air plasmas for water purification

    Science.gov (United States)

    Gucker, Sarah N.; Foster, John E.; Garcia, Maria C.

    2015-10-01

    An underwater steam plasma discharge, in which water itself is the ionizing media, is investigated as a means to introduce advanced oxidation species into contaminated water for the purpose of water purification. The steam discharge avoids the acidification observed with air discharges and also avoids the need for a feed gas, simplifying the system. Steam discharge operation did not result in a pH changes in the processing of water or simulated wastewater, with the actual pH remaining roughly constant during processing. Simulated wastewater has been shown to continue to decompose significantly after steam treatment, suggesting the presence of long-lived plasma produced radicals. During steam discharge operation, nitrate production is limited, and nitrite production was found to be below the detection threshold of (roughly 0.2 mg L-1). The discharge was operated over a broad range of deposited power levels, ranging from approximately 30 W to 300 W. Hydrogen peroxide production was found to scale with increasing power. Additionally, the hydrogen peroxide production efficiency of the discharge was found to be higher than many of the rates reported in the literature to date.

  1. Focusing of plasma flow in an E cross B discharge

    Science.gov (United States)

    Griswold, Martin; Raitses, Yevgeny; Fisch, Nathaniel J.

    2010-11-01

    ExB discharges can be used to accelerate ions in a quasi-neutral plasma. Large ion fluxes can be produced in this way because there is no space charge limitation, however difficulty in specifying the electric field distribution results in large flow divergence [1]. Recent work has identified new methods to control the flow divergence [2,3]. We present the results of new techniques that are designed to further reduce the divergence. [4pt] [1] A.I. Morozov and V.V. Savelyev, Reviews of Plasma Physics vol. 21, B. B. Kadomtsev and V. D. Shafranov, Eds. New York: Consultants Bureau, 2000. [2] Y. Raitses, L.A. Dorf, A.A. Litvak, and N.J. Fisch, Journal of Applied Physics 88 (2000) 1263. [3] A. Smirnov, Y. Raitses, and N.J. Fisch, IEEE Transactions on Plasma Science 36 (2008) 1998.

  2. Relationship between the discharge mode and the spatial oxygen plasma distribution in a large size ferrite inductively coupled plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyun Jun [Department of Electrical Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); R and D Center for PSK-INC Corporation, Hwaseong-si 445-170 (Korea, Republic of); Hwang, Hye Ju; Cho, Jeong Hee; Chae, Hee Sun [R and D Center for PSK-INC Corporation, Hwaseong-si 445-170 (Korea, Republic of); Kim, Dong Hwan [Department of Nanoscale Semiconductor Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Chung, Chin-Wook, E-mail: joykang@hanyang.ac.kr [Department of Electrical Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of)

    2015-04-15

    The electrical characteristics and the spatial distribution of oxygen plasma according to the number of turns in ferrite inductively coupled plasmas (ferrite ICPs) are investigated. Through a new ICP model, which includes the capacitive coupling and the power loss of the ferrite material with the conventional ICP model, the variation of the oxygen discharge characteristics depending on the number of turns is simply understood by the electrical measurement, such as the antenna voltages and the currents. As the number of the turns increases, the capacitive coupling dominantly affects the spatial plasma distribution. This capacitive coupling results in a center focused density profile along the radial direction. In spite of the same discharge conditions (discharge chamber, neutral gas, and pressure), the spatial plasma distribution over 450 mm has drastic changes by increasing number of the turns. In addition, the effect of the negative species to the density profile is compared with the argon discharge characteristics at the same discharge configuration.

  3. Discharge effects on gas flow dynamics in a plasma jet

    Science.gov (United States)

    Xian, Yu Bin; Hasnain Qaisrani, M.; Yue, Yuan Fu; Lu, Xin Pei

    2016-10-01

    Plasma is used as a flow visualization method to display the gas flow of a plasma jet. Using this method, it is found that a discharge in a plasma jet promotes the transition of the gas flow to turbulence. A discharge at intermediate frequency (˜6 kHz in this paper) has a stronger influence on the gas flow than that at lower or higher frequencies. Also, a higher discharge voltage enhances the transition of the gas flow to turbulence. Analysis reveals that pressure modulation induced both by the periodically directed movement of ionized helium and Ohmic heating on the gas flow plays an important role in inducing the transition of the helium flow regime. In addition, since the modulations induced by the high- and low-frequency discharges are determined by the frequency-selective effect, only intermediate-frequency (˜6 kHz) discharges effectively cause the helium flow transition from the laminar to the turbulent flow. Moreover, a discharge with a higher applied voltage makes a stronger impact on the helium flow because it generates stronger modulations. These conclusions are useful in designing cold plasma jets and plasma torches. Moreover, the relationship between the discharge parameters and the gas flow dynamics is a useful reference on active flow control with plasma actuators.

  4. Multifunctional bulk plasma source based on discharge with electron injection

    Energy Technology Data Exchange (ETDEWEB)

    Klimov, A. S.; Medovnik, A. V. [Tomsk State University of Control Systems and Radioelectronics, Tomsk 634050 (Russian Federation); Tyunkov, A. V. [Tomsk State University of Control Systems and Radioelectronics, Tomsk 634050 (Russian Federation); Institute of High Current Electronics, Tomsk 634055 (Russian Federation); Savkin, K. P.; Shandrikov, M. V.; Vizir, A. V. [Institute of High Current Electronics, Tomsk 634055 (Russian Federation)

    2013-01-15

    A bulk plasma source, based on a high-current dc glow discharge with electron injection, is described. Electron injection and some special design features of the plasma arc emitter provide a plasma source with very long periods between maintenance down-times and a long overall lifetime. The source uses a sectioned sputter-electrode array with six individual sputter targets, each of which can be independently biased. This discharge assembly configuration provides multifunctional operation, including plasma generation from different gases (argon, nitrogen, oxygen, acetylene) and deposition of composite metal nitride and oxide coatings.

  5. Measurement of Plasma Density Produced in Dielectric Barrier Discharge for Active Aerodynamic Control with Interferometer

    Institute of Scientific and Technical Information of China (English)

    LI Gang; ZHANG Yi; XU Yan-Ji; LIN Bin; LI Yu-Tong; ZHU Jun-Qiang

    2009-01-01

    We utilize an interferometer to investigate the changes of the refractive index caused by dielectric barrier discharge plasma.The electronic density of the plasma produced is measured and analyzed tentatively.The results show that density of the plasma increases linearly with exciting voltages.

  6. Comparison of atmospheric air plasmas excited by high-voltage nanosecond pulsed discharge and sinusoidal alternating current discharge

    Science.gov (United States)

    Zhang, Shuai; Wang, Wen-chun; Jiang, Peng-chao; Yang, De-zheng; Jia, Li; Wang, Sen

    2013-10-01

    In this paper, atmospheric pressure air discharge plasma in quartz tube is excited by 15 ns high-voltage nanosecond pulsed discharge (HVNPD) and sinusoidal alternating current discharge (SACD), respectively, and a comparison study of these two kinds of discharges is made through visual imaging, electrical characterization, optical detection of active species, and plasma gas temperature. The peak voltage of the power supplies is kept at 16 kV while the pulse repetition rate of nanosecond pulse power supply is 100 Hz, and the frequency of sinusoidal power supply is 10 kHz. Results show that the HVNPD is uniform while the SACD presents filamentary mode. For exciting the same cycles of discharge, the average energy consumption in HVNPD is about 1/13 of the SACD. However, the chemical active species generated by the HVNPD is about 2-9 times than that excited by the SACD. Meanwhile, the rotational and vibrational temperatures have been obtained via fitting the simulated spectrum of N2 (C3Πu → B3Πg, 0-2) with the measured one, and the results show that the plasma gas temperature in the HVNPD remains close to room temperature whereas the plasma gas temperature in the SACD is about 200 K higher than that in HVNPD in the initial phase and continually increases as discharge exposure time goes on.

  7. Plasma Physics Issues in Gas Discharge Laser Development

    Science.gov (United States)

    1991-12-01

    WL-TR-92-2087 PLASMA PHYSICS ISSUES IN GAS DISCHARGE LASER DEVELOPMENT AD-A257 735 ALAN GARSCADDEN MARK J. KUSNER J. GARY EDEN WL/POOC-3 WRIGHT...LASERS INFRARED MOLECULAR jAS LASERS UNCLASSIFIED UNCLASSIFIED UNCLASSIFIED UL Plasma Physics Issues in Gas Discharge Laser Development Alan Garscadden...the close coupling between body of work was not generally useful in laser development . vibrationally excited nitrogen and CO or CO2 . In fact. the First

  8. Study of the Effect of Decrease in the Conductivity Ahead of a Shock Wave in a Glow-Discharge Plasma

    Science.gov (United States)

    Baryshnikov, A. S.; Basargin, I. V.; Bobashev, S. V.; Monakhov, N. A.; Popov, P. A.; Sakharov, V. A.; Chistyakova, M. V.

    2016-05-01

    The electrical conductivity of a glow-discharge plasma ahead of a shock wave moving perpendicularly to the discharge axis has been investigated using a double electric probe. The obtained results have shown that the interaction of the shock wave with the glow-discharge plasma is accompanied by a change in its conductivity in the entire investigated volume simultaneously.

  9. Discharge processes and an electrical model of atmospheric pressure plasma jets in argon

    Science.gov (United States)

    Fang, Zhi; Shao, Tao; Yang, Jing; Zhang, Cheng

    2016-01-01

    In this paper, an atmospheric pressure plasma discharge in argon was generated using a needle-to-ring electrode configuration driven by a sinusoidal excitation voltage. The electric discharge processes and discharge characteristics were investigated by inspecting the voltage-current waveforms, Lissajous curves and lighting emission images. The change in discharge mode with applied voltage amplitude was studied and characterised, and three modes of corona discharge, dielectric barrier discharge (DBD) and jet discharge were identified, which appeared in turn with increasing applied voltage and can be distinguished clearly from the measured voltage-current waveforms, light-emission images and the changing gradient of discharge power with applied voltage. Based on the experimental results and discharge mechanism analysis, an equivalent electrical model and the corresponding equivalent circuit for characterising the whole discharge processes accurately was proposed, and the three discharge stages were characterised separately. A voltage-controlled current source (VCCS) associated with a resistance and a capacitance were used to represent the DBD stage, and the plasma plume and corona discharge were modelled by a variable capacitor in series with a variable resistor. Other factors that can influence the discharge, such as lead and stray capacitance values of the circuit, were also considered in the proposed model. Contribution to the Topical Issue "Recent Breakthroughs in Microplasma Science and Technology", edited by Kurt Becker, Jose Lopez, David Staack, Klaus-Dieter Weltmann and Wei Dong Zhu.

  10. Numerical simulation of discharge plasma generation and nitriding the metals and alloys

    Science.gov (United States)

    Koval, T. V.; Manakov, R. A.; Nguyen Bao, Hung; Tran My, Kim An

    2017-01-01

    This research provides the numerical simulation of the plasma generation in a hollow cathode as well as the diffusion of nitrogen atoms into the metal in the low-pressure glow discharge plasma. The characteristics of the gas discharge were obtained and the relation of the basic technological parameters and the structural and phase state of the nitrided material were defined. Authors provided the comparison of calculations with the experimental results of titanium nitriding by low-pressure glow discharge plasma in a hollow cathode.

  11. Conversion of Methane by Dielectric-barrier Discharge Plasma Method-Comparison with Microwave Plasma Method

    National Research Council Canada - National Science Library

    Konno, Katsuya; Kobayashi, Motoki; Onoe, Kaoru; Yamaguchi, Tatsuaki

    2010-01-01

      Methane conversion by the dielectric-barrier discharge plasma method (DBD) was compared with our previous findings for the microwave plasma method (MW). The power (Pw), initial pressure (P0) and flow rate (F0...

  12. Pathway Study on Dielectric Barrier Discharge Plasma Conversion of Hexane

    NARCIS (Netherlands)

    Agiral, Anil; Boyadjian, Cassia; Seshan, K.; Lefferts, Leon; Gardeniers, J.G.E. (Han)

    2010-01-01

    A plasma reactor based on dielectric barrier discharge has been developed for oxidative cracking of hexane to yield olefins at atmospheric pressure. Dissociation of hexane in the presence of oxygen with nonequilibrium plasma state represents complex chemistry, and both conversion and product selecti

  13. Discharge Characteristics of DC Arc Water Plasma for Environmental Applications

    Institute of Scientific and Technical Information of China (English)

    LI Tianming; Sooseok CHOI; Takayuki WATANABE

    2012-01-01

    A water plasma was generated by DC arc discharge with a hafnium embedded rodtype cathode and a nozzle-type anode. The discharge characteristics were examined by changing the operation parameter of the arc current. The dynamic behavior of the arc discharge led to significant fluctuations in the arc voltage and its frequency. Analyses of the high speed image and the arc voltage waveform showed that the arc discharge was in the restrike mode and its frequency varied within several tens of kilohertz according to the operating conditions. The larger thermal plasma volume was generated by the higher flow from the forming steam with a higher restrike frequency in the higher arc current conditions. In addition, the characteristics of the water plasma jet were investigated by means of optical emission spectroscopy to identify the abundant radicals required in an efficient waste treatment process.

  14. Improvement of water quality using dielectric barrier discharge plasma

    Science.gov (United States)

    Quyen, N. T.; Traikool, T.; Nitisoravut, R.; Onjun, T.

    2017-06-01

    The improvement of water quality using by atmospheric plasma produced from a dielectric barrier discharge (DBD) was studied. An experiment was set-up with a 4 mm diameter pipe, which contains 2 electrodes and has an air flow with the rate of 15 liters per minute. Surface water, domestic wastewater and DI water were treated with the DBD plasma for some period of time. Electricity was supplied at 3.5 kV with the frequency of 5.5 kHz. Some key parameters of water quality includes the level of chemical oxygen demand (COD), total suspended solid (TSS), color, and odor are measured before and after. The result showed that strong acid with pH below 2 was observed after 60 minutes plasma treatment for the DI water, while the surface water and wastewater needs about 120 minutes to pH below 2 even though the pH value are about the same at the beginning. Moreover, It was formed that the COD, TSS microorganism was noticeably decreased, therefore the increasing of transparency level. This result confirms that atmospheric DBD plasma generated acidity in water as reduce amount of organic and suspended solid in water.

  15. How does a probe inserted into the discharge influence the plasma structure?

    Science.gov (United States)

    Yordanov, D.; Lishev, St.; Shivarova, A.

    2016-05-01

    Shielding the bias applied to the probe by the sheath formed around it and determination of parameters of unperturbed plasmas are in the basis of the probe diagnostics. The results from a two-dimensional model of a discharge with a probe inserted in it show that the probe influences the spatial distribution of the plasma parameters in the entire discharge. The increase (although slight) in the electron temperature, due to the increased losses of charged particles on the additional wall in the discharge (mainly the probe holder), leads to redistribution of the plasma density and plasma potential, as shown by the results obtained at the floating potential of the probe. The deviations due to the bias applied to the probe tip are stronger in the ion saturation region of the probe characteristics. The pattern of the spatial redistribution of the plasma parameters advances together with the movement of the probe deeper in the discharge. Although probe sheaths and probe characteristics resulting from the model are shown, the study does not aim at discussions on the theories for determination of the plasma density from the ion saturation current. Regardless of the modifications in the plasma behavior in the entire discharge, the deviations of the plasma parameters at the position of the probe tip and, respectively, the uncertainty which should be added as an error when the accuracy of the probe diagnostics is estimated do not exceed 10%. Consequently, the electron density and temperature obtained, respectively, at the position of the plasma potential on the probe characteristics and from its transition region are in reasonable agreement with the results from the model of the discharge without a probe. Being in the scope of research on a source of negative hydrogen ions with the design of a matrix of small radius inductive discharges, the model is specified for a low-pressure hydrogen discharge sustained in a small-radius tube.

  16. Electrostatic modelling of dual frequency rf plasma discharges

    Energy Technology Data Exchange (ETDEWEB)

    Boyle, P C; Ellingboe, A R; Turner, M M [Plasma Research Laboratory, National Centre for Plasma Science and Technology and School of Physical Sciences, Dublin City University, Dublin 9 (Ireland)

    2004-08-01

    Particle-in-cell simulations have been used to study the nature of dual frequency plasma discharges. It is observed that both the ion flux on to the electrodes and the ion bombardment energy on to the electrodes can be controlled independently. There are two separate regimes in which this occurs. At large electrode separation, the ion current is controlled by varying the total discharge current, J{sub lf} + J{sub hf}. At small electrode separations, the ion flux can be controlled by varying the high frequency power source. In both regimes, the energy of the ions bombarding the electrodes is then determined by the low frequency voltage. A consequence of using dual frequencies to power the device is that the sheath width increases linearly as the low frequency power source is increased. This results in the dimensions of the bulk plasma decreasing, causing the electron temperature to increase for devices with electrode separations that are of comparable size to the electrode separation. In order to better understand the underlying physics involved within these devices an analytical global model has been developed which can explain many of the characteristics observed in the simulations.

  17. Boosting persistence time of laser-induced plasma by electric arc discharge for optical emission spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Eschlböck-Fuchs, S., E-mail: simon.eschlboeck-fuchs@jku.at [Christian Doppler Laboratory for Laser-Assisted Diagnostics, Institute of Applied Physics, Johannes Kepler University Linz, A-4040 Linz (Austria); Kolmhofer, P.J.; Bodea, M.A.; Hechenberger, J.G.; Huber, N. [Christian Doppler Laboratory for Laser-Assisted Diagnostics, Institute of Applied Physics, Johannes Kepler University Linz, A-4040 Linz (Austria); Rössler, R. [voestalpine Stahl GmbH, A-4031 Linz (Austria); Pedarnig, J.D., E-mail: johannes.pedarnig@jku.at [Christian Doppler Laboratory for Laser-Assisted Diagnostics, Institute of Applied Physics, Johannes Kepler University Linz, A-4040 Linz (Austria)

    2015-07-01

    Plasma induced by nanosecond laser ablation is re-excited by a pulsed electric discharge and the parameters and optical emission of the plasma are measured. The discharge is a low-voltage and high-current electric arc that is triggered by the laser-induced plasma and slowly decaying with time. The optical emission of such combined plasma lasts up to several milliseconds which is much longer than without re-excitation (μs range). The emission spectra of re-excited plasma measured on different sample materials show higher line intensities than spectra measured by conventional laser-induced breakdown spectroscopy (LIBS). Moreover, emission lines of fluorine (spectral range 683–691 nm) and sulfur (range 520–550 nm) not detected by conventional LIBS become easily detectable with the combined plasma. The concentration of major components in metallurgical slags, as determined by calibration-free LIBS, agrees very well to the reference data evaluating the spectra taken from re-excited plasma. - Highlights: • Persistence time of laser-induced plasma in air is increased from ~ 10 μs to ~ 1 ms. • Laser-induced plasma triggers an electric arc discharge that boosts the plasma. • The combined laser-arc plasma is in LTE state over very long time (ms range). • CF-LIBS method delivers accurate results evaluating spectra of combined plasma. • Emission from S and F, not detected by LIBS, is detected with combined plasma.

  18. [Investigation on the Spectral Characteristics of a Plasma Jet in Atmospheric Argon Glow Discharge].

    Science.gov (United States)

    Li, Xue-chen; Zhang, Chun-yan; Li, Ji-yuan; Bao, Wen-ting

    2015-12-01

    Plasma jet is a kind of important plasma source at atmospheric pressure. In recent years, it becomes an important hot topic in the field of low temperature plasma. In this paper, using a tungsten needle and a tungsten wire mesh, a direct-current excited jet is developed to operate in argon at atmospheric pressure. In the atmospheric pressure argon, the plasma jet can produce a stable plasma plume. By using the method of emission spectroscopy, the parameters of the plasma plume are investigated. The discharge emits dazzling white light from the area between the tungsten needle electrode and the wire mesh electrode. A plasma plume with a flame shape appears outside the tungsten wire mesh electrode. For a constant value of voltage (U = 13.5 kV), the length of the plasma plume increases with the gas flow rate. For a constant value of the gas flow rate(10 L · min⁻¹), the length of the plasma plume increases with the voltage. The voltage is inversely proportional to the current under the constant gas flow rate. In other words, the voltage decreases with the discharge current, which indicates that a glow discharge is formed in the plasma jet. Optical emission spectrum in 300 to 800 nm is collected from the direct-current excited plasma jet. By Boltzmann plot method, the excited electron temperature of the plasma plume is investigated as a function of the applied voltage or the gas flow rate. Results show that the excited electron temperature increases with decreasing applied voltage under the constant gas flow. Moreover, it increases with decreasing the gas flow under the constant voltage. Based on the discharge theory, these experimental phenomena are explained qualitatively. These results are of great importance to the development of atmospheric pressure uniform discharge plasma source and its application in industrial field.

  19. Focused beams of fast neutral atoms in glow discharge plasma

    Science.gov (United States)

    Grigoriev, S. N.; Melnik, Yu. A.; Metel, A. S.; Volosova, M. A.

    2017-06-01

    Glow discharge with electrostatic confinement of electrons in a vacuum chamber allows plasma processing of conductive products in a wide pressure range of p = 0.01 - 5 Pa. To assist processing of a small dielectric product with a concentrated on its surface beam of fast neutral atoms, which do not cause charge effects, ions from the discharge plasma are accelerated towards the product and transformed into fast atoms. The beam is produced using a negatively biased cylindrical or a spherical grid immersed in the plasma. Ions accelerated by the grid turn into fast neutral atoms at p > 0.1 Pa due to charge exchange collisions with gas atoms in the space charge sheaths adjoining the grid. The atoms form a diverging neutral beam and a converging beam propagating from the grid in opposite directions. The beam propagating from the concave surface of a 0.24-m-wide cylindrical grid is focused on a target within a 10-mm-wide stripe, and the beam from the 0.24-m-diameter spherical grid is focused within a 10-mm-diameter circle. At the bias voltage U = 5 kV and p ˜ 0.1 Pa, the energy of fast argon atoms is distributed continuously from zero to eU ˜ 5 keV. The pressure increase to 1 Pa results in the tenfold growth of their equivalent current and a decrease in the mean energy by an order of magnitude, which substantially raises the efficiency of material etching. Sharpening by the beam of ceramic knife-blades proved that the new method for the generation of concentrated fast atom beams can be effectively used for the processing of dielectric materials in vacuum.

  20. Characteristics of cold atmospheric plasma source based on low-current pulsed discharge with coaxial electrodes

    Science.gov (United States)

    Bureyev, O. A.; Surkov, Yu S.; Spirina, A. V.

    2017-05-01

    This work investigates the characteristics of the gas discharge system used to create an atmospheric pressure plasma flow. The plasma jet design with a cylindrical graphite cathode and an anode rod located on the axis of the system allows to realize regularly reproducible spark breakdowns mode with a frequency ∼ 5 kHz and a duration ∼ 40 μs. The device generates a cold atmospheric plasma flame with 1 cm in diameter in the flow of various plasma forming gases including nitrogen and air at about 100 mA average discharge current. In the described construction the cathode spots of individual spark channels randomly move along the inner surface of the graphite electrode creating the secondary plasma stream time-average distributed throughout the whole exit aperture area after the decay of numerous filamentary discharge channels. The results of the spectral diagnostics of plasma in the discharge gap and in the stream coming out of the source are presented. Despite the low temperature of atoms and molecules in plasma stream the cathode spots operation with temperature of ∼ 4000 °C at a graphite electrode inside a discharge system enables to saturate the plasma by CN-radicals and atomic carbon in the case of using nitrogen as the working gas.

  1. Temporal modulation of plasma species in atmospheric dielectric barrier discharges

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Aijun; Wang, Xiaohua, E-mail: xhw@mail.xjtu.edu.cn, E-mail: mzrong@mail.xjtu.edu.cn; Liu, Dingxin; Rong, Mingzhe, E-mail: xhw@mail.xjtu.edu.cn, E-mail: mzrong@mail.xjtu.edu.cn [Centre for Plasma Biomedicine, State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Xi' an 710049 (China); Kong, Michael G. [Centre for Plasma Biomedicine, State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Xi' an 710049 (China); Frank Reidy Research Center for Bioelectrics, Department of Electrical and Computer Engineering, Old Dominion University, Virginia 23508 (United States); Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, Virginia 23529 (United States)

    2014-07-15

    The atmospheric pressure dielectric barrier discharge in helium is a pulsed discharge in nature and the moment of maximum species densities is almost consistent with peak discharge current density. In this paper, a one-dimensional fluid model is used to investigate the temporal structure of plasma species in an atmospheric He-N{sub 2} dielectric barrier discharge (DBD). It is demonstrated that there exist microsecond delays of the moments of the maximum electron and ion densities from the peak of discharge current density. These time delays are caused by a competition between the electron impact and Penning ionizations, modulated by the N{sub 2} level in the plasma-forming gas. Besides, significant electron wall losses lead to the DBD being more positively charged and, with a distinct temporal separation in the peak electron and cation densities, the plasma is characterized with repetitive bursts of net positive charges. The temporal details of ionic and reactive plasma species may provide a new idea for some biological processes.

  2. Simulation of polyatomic discharges for thin film deposition processes in low-pressure plasma reactors

    Science.gov (United States)

    Bera, Kallol

    Comprehensive multi-dimensional self-consistent numerical fluid models for radio-frequency capacitively and inductively coupled methane discharges were developed to predict diamond-like-carbon thin film deposition/etching rate on the wafer. A numerical model of glow discharge provides insight on the physical phenomena in the discharge leading to better understanding and design of the reactor. The developed discharge models included detailed discharge physics, gas-phase chemistry and surface chemistry modeling. To understand the basic discharge phenomena, one- dimensional radio frequency capacitively coupled Ar plasma was simulated using a fluid model. The model was modified for methane plasma to predict the profiles of the plasma variables. The model was then extended to two- dimensional cylindrical coordinates to capture the effects of asymmetry of the reactor on the plasma variables. The necessary dc bias for the discharge was predicted such that the cycle-averaged current to the powered electrode was zero. A discharge chemistry model was also developed to predict various radical and neutral densities in the plasma, and their fluxes to the cathode. The species fluxes are used to predict film deposition rate and the properties of the deposited film. The model predictions of plasma density, self-generated de bias, cathode current and plasma potential compared well with the experimental results. A high density plasma with inductive coupling at low pressure was also considered. Separate rf bias and dc bias are applied to the substrate holder to modulate the ion energy. The present model simulates electron, ion and neutral transport, including detailed discharge and surface chemistry. The model has been implemented for methane discharge to obtain deposition/etching of thin carbon film on the wafer. To the author's knowledge, this is the first attempt to simulate capacitively and inductively coupled plasmas self-consistently for a depositing gas under the operating

  3. Plasma-density evolution in compact polyacetal capillary discharges

    Energy Technology Data Exchange (ETDEWEB)

    Tomasel, F.G.; Rocca, J.J.; Cortazar, O.D.; Szapiro, B.T. (Electrical Engineering Department, Colorado State University, Fort Collins, Colorado 80523 (United States)); Lee, R.W. (Lawrence Livermore National Laboratory, Livermore, California 94550 (United States))

    1993-05-01

    We have measured the temporal evolution of the electron density of plasmas produced in polyacetal capillaries with diameters between 0.5 and 1.5 mm excited by 110-ns full-width-at-half-maximum discharge pulses with currents between 13 and 42 kA. The electron density was determined from Stark-broadened line profiles of the 4[ital f]-3[ital d] O VI transition taking into account opacity effects. The electron density was found to increase continuously during the rise of the current pulse, and to decrease near the end of the current pulse, when a drop in plasma temperature causes the degree of ionization of the plasma to decrease. The peak plasma density in a 1-mm capillary excited by a 24-kA pulse was measured to be 5[times]10[sup 19] cm[sup [minus]3]. The plasma density was observed to increase linearly with discharge energy from 7.5[times]10[sup 18] cm[sup [minus]3] for a 5-J discharge to 5[times]10[sup 19] cm[sup [minus]3] for a 30-J discharge in a 1.5-mm-diam. capillary.

  4. Carbon dust particles in a beam-plasma discharge

    Science.gov (United States)

    Koval, O. A.; Vizgalov, V.; Shalpegin, A. V.

    2016-09-01

    This paper focuses on dynamics of micro-sized carbon dust grains in beam-plasma discharge (BPD) plasmas. It was demonstrated that injected dust particles can be captured and transported along the discharge. Longitudinal average velocity of the particles in the central area of the plasma column was 17 m/sec, and 2 m/sec in the periphery. Dust injection caused a decrease of emission intensity of metastable nitrogen molecular ion. This effect is suggested for a spectroscopy method for particles’ potential measurements. Five-micron radius carbon dust grains obtained potential above 500 V in the experiments on PR-2 installation, proving the feasibility of BPDs for the charging of fine dust particles up to high potential values, unattainable in similar plasma conditions.

  5. Numerical Modeling of the Atmospheric-Pressure Helium Plasma Formed During Spark-to-Glow Discharge Transition

    Science.gov (United States)

    Demkin, V. P.; Melnichuk, S. V.

    2017-06-01

    Results of numerical experiment on modeling of the atmospheric-pressure plasma formed during the spark-to-glow discharge transition in helium in low-current non-stationary plasmatron are presented. The numerical experiment is performed using the developed 2D physical and mathematical plasma model in the drift-diffusion approximation. Results of numerical calculation of the dynamics of discharge evolution are confirmed by the experimental data on the atmospheric-pressure plasma dynamics formed in the plasmatron during the spark-to-glow discharge transition. It is demonstrated that with preset initial conditions characteristic for spark breakdown, further discharge evolution leads to the formation of the near-cathode zone of the potential drop and the pulsed behavior of the electric current of the discharge. After the current pulse, the discharge transforms into the quasi-stationary mode with parameters characteristic for the glow discharge with monotonically increasing electric current and transverse dimensions of the plasma column.

  6. High Frequency Discharge Plasma Induced Grafting of Polystyrene onto Titanium Dioxide Powder

    Institute of Scientific and Technical Information of China (English)

    ZHONG Shaofeng; OU Qiongrong; MENG Yuedong

    2007-01-01

    Grafting of polystyrene (PS) onto titanium dioxide powder was investigated. The graft polymerization reaction was induced by high frequency discharge produced N2 plasma treatment of the surfaces of titanium dioxide. IR , XPS and TGA results show that PS was grafted on the titanium dioxide powder. And the crystal structure of the titanium dioxide powder observed by XRD was unchanged after plasma treatment.

  7. Dynamics of the plasma current sheath in plasma focus discharges in different gases

    Energy Technology Data Exchange (ETDEWEB)

    Vinogradov, V. P.; Krauz, V. I., E-mail: krauz-vi@nrcki.ru [National Research Center Kurchatov Institute (Russian Federation); Mokeev, A. N. [Project Center ITER (Russian Federation); Myalton, V. V.; Kharrasov, A. M. [National Research Center Kurchatov Institute (Russian Federation)

    2016-12-15

    The shape of the plasma current sheath (PCS) in the final stage of its radial compression, the dynamics of pinching, and the subsequent pinch decay in plasma focus (PF) discharges in different gases are studied using an improved multichannel system of electron-optical plasma photography and a newly elaborated synchronization system. The PCS structure in discharges in heavy gases (Ne, Ar) is found to differ significantly from that in discharges in hydrogen and deuterium. The influence of a heavy gas (Xe) additive to hydrogen and deuterium on the structure and compression dynamics of the PCS is investigated.

  8. Two-stage plasma gun based on a gas discharge with a self-heating hollow emitter.

    Science.gov (United States)

    Vizir, A V; Tyunkov, A V; Shandrikov, M V; Oks, E M

    2010-02-01

    The paper presents the results of tests of a new compact two-stage bulk gas plasma gun. The plasma gun is based on a nonself-sustained gas discharge with an electron emitter based on a discharge with a self-heating hollow cathode. The operating characteristics of the plasma gun are investigated. The discharge system makes it possible to produce uniform and stable gas plasma in the dc mode with a plasma density up to 3x10(9) cm(-3) at an operating gas pressure in the vacuum chamber of less than 2x10(-2) Pa. The device features high power efficiency, design simplicity, and compactness.

  9. Evaluation of the potentials of humic acid removal in water by gas phase surface discharge plasma.

    Science.gov (United States)

    Wang, Tiecheng; Qu, Guangzhou; Ren, Jingyu; Yan, Qiuhe; Sun, Qiuhong; Liang, Dongli; Hu, Shibin

    2016-02-01

    Degradation of humic acid (HA), a predominant type of natural organic matter in ground water and surface waters, was conducted using a gas phase surface discharge plasma system. HA standard and two surface waters (Wetland, and Weihe River) were selected as the targets. The experimental results showed that about 90.9% of standard HA was smoothly removed within 40 min's discharge plasma treatment at discharge voltage 23.0 kV, and the removal process fitted the first-order kinetic model. Roles of some active species in HA removal were studied by evaluating the effects of solution pH and OH radical scavenger; and the results presented that O3 and OH radical played significant roles in HA removal. Scanning electron microscope (SEM) and FTIR analysis showed that HA surface topography and molecular structure were changed during discharge plasma process. The mineralization of HA was analyzed by UV-Vis spectrum, dissolved organic carbon (DOC), specific UV absorbance (SUVA), UV absorption ratios, and excitation-emission matrix (EEM) fluorescence. The formation of disinfection by-products during HA sample chlorination was also identified, and CHCl3 was detected as the main disinfection by-product, but discharge plasma treatment could suppress its formation to a certain extent. In addition, approximately 82.3% and 67.9% of UV254 were removed for the Weihe River water and the Wetland water after 40 min of discharge plasma treatment.

  10. Dielectric barrier Discharge Plasma Actuator Characterization and Application

    NARCIS (Netherlands)

    Correale, G.

    2016-01-01

    An experimental investigation about nanosecond Dielectric Barrier Discharge (ns-DBD) plasma actuator is presented in this thesis. This work aimed to answer fundamental questions on the actuation mechanism of this device. In order to do so, parametric studies in a quiescent air as well as laminar

  11. Dielectric barrier Discharge Plasma Actuator Characterization and Application

    NARCIS (Netherlands)

    Correale, G.

    2016-01-01

    An experimental investigation about nanosecond Dielectric Barrier Discharge (ns-DBD) plasma actuator is presented in this thesis. This work aimed to answer fundamental questions on the actuation mechanism of this device. In order to do so, parametric studies in a quiescent air as well as laminar bou

  12. Characterization of Plasma Polymerized Hexamethyldisiloxane Films Prepared by Arc Discharge

    NARCIS (Netherlands)

    Lazauskas, A.; Baltrusaitis, Jonas; Grigaliunas, V.; Jucius, D; Guobiene, A.; Prosycevas, I.; Narmontas, P.

    2014-01-01

    Herein, we present a simple method for fabricating plasma polymerized hexamethyldisiloxane films (pp-HMDSO) possessing superhydrophobic characteristics via arc discharge. The pp-HMDSO films were deposited on a soda–lime–silica float glass using HMDSO monomer vapor as a precursor. A detailed surface

  13. Characteristics of an Atmospheric Discharge Plasma as an RF Antenna

    Science.gov (United States)

    1982-05-27

    continuing PLASMA AS AN RF ANTENNA problem 6. PERFORMIN4G ORO . REPORT NUM99fR 7. AUTNOR(j .C ONTRACT OR GRANT MUMDERp(s) T. Dwyer, J1. R. Greig. D. P. Murphy...path) of the plasma antenna and energy to create and sustain the plasma were supplied directly in the form of an electric discharge a totally new balance...the ground plane, G. The lead was terminated in a corona ball with a small protrusion sticking out towards the laser-designated path. The end of the

  14. Generation of intense soft X-rays from capillary discharge plasmas

    Indian Academy of Sciences (India)

    Y B S R Prasad; S Nigam; K Aneesh; S Barnwal; P K Tripathi; P A Naik; C P Navathe; P D Gupta

    2011-06-01

    X-ray lasing through high voltage, high current discharges in gas filled capillaries has been demonstrated in several laboratories. This method gives highest number of X-ray photons per pulse. The fast varying current and the j x B magnetic force compress the plasma towards the axis forming a hot, dense, line plasma, wherein under appropriate discharge conditions lasing occurs. At Laser Plasma Division, RRCAT, a program on high voltage capillary discharge had been started. The system consists of a 400 kV Marx bank, water line capacitor, spark gap and capillary chamber. The initial results of the emission of intense short soft X-ray pulses (5–10 ns) from the capillary discharge are reported.

  15. Growth Enhancement of Radish Sprouts Induced by Low Pressure O2 Radio Frequency Discharge Plasma Irradiation

    Science.gov (United States)

    Kitazaki, Satoshi; Koga, Kazunori; Shiratani, Masaharu; Hayashi, Nobuya

    2012-01-01

    We studied growth enhancement of radish sprouts (Raphanus sativus L.) induced by low pressure O2 radio frequency (RF) discharge plasma irradiation. The average length of radish sprouts cultivated for 7 days after O2 plasma irradiation is 30-60% greater than that without irradiation. O2 plasma irradiation does not affect seed germination. The experimental results reveal that oxygen related radicals strongly enhance growth, whereas ions and photons do not.

  16. Preliminary experiment on the negative magneto-resistance effect in a weakly ionized discharge plasma

    Energy Technology Data Exchange (ETDEWEB)

    Nagata, M.

    2002-04-01

    Compared with the interest in the magneto-resistance effect in solid conductors, the effect in a gas plasma has hardly been addressed. In this work, a theoretical result that a magneto-resistance in an infinite plasma decreases is examined experimentally in an actual discharge plasma. Furthermore, a modified expression for the ambipolar diffusion coefficient in the case where electrons are scattered by heavy neutral atoms is presented. (author)

  17. Experimental Study on Indoor Air Cleaning Technique of Nano-Titania Catalysis Under Plasma Discharge

    Institute of Scientific and Technical Information of China (English)

    GAO Deli; YANG Xuechang; ZHOU Fei; WU Yuhuang

    2008-01-01

    In this study, a new technique of air cleaning by plasma combined with catalyst was proposed, which consisted of electrostatic precipitation, volatile organic compounds (VOCs) decomposition and sterilization. A novel indoor air purifier based on this technique was adopted. The experimental results showed that formaldehyde decomposition by the plasma-catalyst hybrid system was more efficient than that by plasma only. Positive discharge was better than negative discharge in formaldehyde removal. Meanwhile, the outlet concentration of ozone byproduct was effectively reduced by the nano-titania catalyst.

  18. Temperature and Nitric Oxide Generation in a Pulsed Arc Discharge Plasma

    Institute of Scientific and Technical Information of China (English)

    T.NAMIHIRA; S.SAKAI; M.MATSUDA; D.WANG; T.KIYAN; H.AKIYAMA; K.OKAMOTO; K.TODA

    2007-01-01

    Nitric oxide (NO) is increasingly being used in medical treatments of high blood pressure,acute respiratory distress syndrome and other illnesses related to the lungs.Currently a NO inhalation system consists of a gas cylinder of N2 mixed with a high concentration of NO.This arrangement is potentially risky due to the possibility of an accidental leak of NO from the cylinder.The presence of NO in the air leads to the formation of nitric dioxide (NO2),which is toxic to the lungs.Therefore,an on-site generator of NO would be highly desirable for medical doctors to use with patients with lung disease.To develop the NO inhalation system without a gas cylinder,which would include a high concentration of NO,NAMIHIRA et al have recently reported on the production of NO from room air using a pulsed arc discharge.In the present work,the temperature of the pulsed arc discharge plasma used to generate NO was measured to optimize the discharge condition.The results of the temperature measurements showed the temperature of the pulsed arc discharge plasma reached about 10,000 K immediately after discharge initiation and gradually decreased over tens of microseconds.In addition,it was found that NO was formed in a discharge plasma having temperatures higher than 9,000 K and a smaller input energy into the discharge plasma generates NO more efficiently than a larger one.

  19. Formation of positive ions in hydrocarbon containing dielectric barrier discharge plasmas

    Science.gov (United States)

    Mihaila, Ilarion; Pohoata, Valentin; Jijie, Roxana; Nastuta, Andrei Vasile; Rusu, Ioana Alexandra; Topala, Ionut

    2016-12-01

    Low temperature atmospheric pressure plasma devices are suitable experimental solutions to generate transitory molecular environments with various applications. In this study we present experimental results regarding the plasma chemistry of dielectric barrier discharges (DBD) in helium - hydrogen (0.1%) - hydrocarbons (1.2%) mixtures. Four types of hydrocarbon gases were studied: methane (CH4), ethane (C2H6), propane (C3H8), and butane (C4H10). Discharge diagnosis and monitoring was assured by electrical measurements and optical emission spectroscopy. Molecular beam mass spectrometry is engaged to sample positive ions populations from two different plasma sources. Dissociation and generation of higher-chain and cyclic (aromatic) hydrocarbons were discussed as a function of feed gas and discharge geometry. We found a strong influence of these parameters on both molecular mass distribution and recombination processes in the plasma volume.

  20. Temporal evolution of electron density and temperature in capillary discharge plasmas

    Science.gov (United States)

    Oh, Seong Y.; Uhm, Han S.; Kang, Hoonsoo; Lee, In W.; Suk, Hyyong

    2010-05-01

    Time-resolved spectroscopic measurements of a capillary discharge plasma of helium gas were carried out to obtain detailed information about dynamics of the discharge plasma column, where the fast plasma dynamics is determined by the electron density and temperature. Our measurements show that the electron density of the capillary plasma column increases sharply after gas breakdown and reaches its peak of the order of 1018 cm-3 within less than 100 ns, and then it decreases as time goes by. The result indicates that a peak electron density of 2.3×1018 cm-3 occurs about 65 ns after formation of the discharge current, which is ideal for laser wakefield acceleration experiments reported by Karsch et al. [New J. Phys. 9, 415 (2007)].

  1. Decomposition of toluene in a gliding arc discharge plasma reactor

    Energy Technology Data Exchange (ETDEWEB)

    Du Changming [School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Yan Jianhua [Institute for Thermal Power Engineering, Zhejiang University, Hangzhou 310027 (China); Cheron, Bruno [UMR 6614 (CORIA), University of Rouen, 76821 Mont Saint Aignan (France)

    2007-11-15

    The decomposition of toluene in a gliding arc discharge (glidarc) was performed and studied. Experimental results indicate that the glidarc technology can effectively decompose toluene molecules and has bright prospects of being applied as an alternative tool to decompose volatile organic compounds. It is found that a change in the electrode material had an insignificant effect on the toluene removal efficiency. The toluene removal efficiency increases with increasing inlet gas temperature. The water vapor present in the gas mixture has a favorable effect on the toluene decomposition in the plasma. The energy efficiency is 29.46 g (kWh{sup -1}) at a relative humidity of 50% and a specific energy input of 0.26 kWh m{sup -3}, which is higher than other types of non-thermal plasmas. Too much or too little oxygen content does not favor toluene decomposition. The major gas phase products detected by FT-IR from the decomposition of toluene with air participation were CO, CO{sub 2}, H{sub 2}O and NO{sub 2}. Some brown depositions were found on the surface of the electrodes, which were polar oxygenous and nitrogenous compounds determined by the GC-MS analysis, such as benzaldehyde, benzoic acid, quinine and nitrophenol from the reaction of toluene with radicals. A possible mechanism for toluene destruction via glidarc technology is proposed and summarized.

  2. Plasma Catalysis of Methane Decomposition in Pulse Microwave Discharge

    Science.gov (United States)

    Potapkin, B.; Rusanov, V.; Jivotov, V.; Babaritski, A.; Potechin, S.; Etievant, C.

    1997-10-01

    Investigation of plasma catalysis effects in various chemical reactions, such as SO2 and hydrocarbons oxidation, ammonia and nitrogen oxides synthesis, has been of interest for many decades. Present work describes the first experimental observation and theoretical analysis of plasma catalysis effects in the case of endothermic methane decomposition into molecular hydrogen and carbon black. Process energy requirements are coverd mainly by low potential gas thermal energy while plasma is used for acceleration of chemical reactions via active species generation. The experiments were done as follows: (i) methane was preheated in a conventional heat exchanger up to about 40-65 ^oC where thermal methane decomposition is limited by process kinetics, (ii) methane was passed through a non-equilibrium pulse microwave discharge (9.04 GHz, pulse duration 1 μs). Experiments have shown a strong catalytic effect of plasma on methane decomposition. The degree of conversion after discharge increased drastically, despite gas cooling, because of heat absorption in the methane decomposition reaction. Theoretical analysis of process kinetics and energy balance gave clear evidence of the catalytic effect of plasma under experimental conditions. The estimated chain length was about 300. The possible mechanism of plasma catalysis, the ion-molecular chain Winchester mechanism, is proposed and described.

  3. A diagnostic system for electrical faults in a high current discharge plasma setup.

    Science.gov (United States)

    Nigam, S; Aneesh, K; Navathe, C P; Gupta, P D

    2011-02-01

    A diagnostic system to detect electrical faults inside a coaxial high current discharge device is presented here. This technique utilizes two biconical antennas picking up electromagnetic radiation from the discharge device, a voltage divider sensing input voltage, and a Rogowski coil measuring the main discharge current. A computer program then analyses frequency components in these signals and provides information as to whether the discharge event was normal or any breakdown fault occurred inside the coaxial device. The diagnostic system is developed for a 450 kV and 50 kA capillary discharge plasma setup. For the setup various possible faults are analyzed by electrical simulation, followed by experimental results. In the case of normal discharge through the capillary load the dominant frequency is ∼4 MHz. Under faulty conditions, the peak in magnitude versus frequency plot of the antenna signal changes according to the fault position which involves different paths causing variation in the equivalent circuit elements.

  4. A diagnostic system for electrical faults in a high current discharge plasma setup

    Science.gov (United States)

    Nigam, S.; Aneesh, K.; Navathe, C. P.; Gupta, P. D.

    2011-02-01

    A diagnostic system to detect electrical faults inside a coaxial high current discharge device is presented here. This technique utilizes two biconical antennas picking up electromagnetic radiation from the discharge device, a voltage divider sensing input voltage, and a Rogowski coil measuring the main discharge current. A computer program then analyses frequency components in these signals and provides information as to whether the discharge event was normal or any breakdown fault occurred inside the coaxial device. The diagnostic system is developed for a 450 kV and 50 kA capillary discharge plasma setup. For the setup various possible faults are analyzed by electrical simulation, followed by experimental results. In the case of normal discharge through the capillary load the dominant frequency is ˜4 MHz. Under faulty conditions, the peak in magnitude versus frequency plot of the antenna signal changes according to the fault position which involves different paths causing variation in the equivalent circuit elements.

  5. Structural properties of complex plasmas in a homogeneous dc discharge.

    Science.gov (United States)

    Mitic, S; Klumov, B A; Konopka, U; Thoma, M H; Morfill, G E

    2008-09-19

    We report on the first three-dimensional (3D) complex plasma structure analysis for an experiment that was performed in an elongated discharge tube in the absence of striations. The low frequency discharge was established with 1 kHz alternating dc current through a cylindrical glass tube filled with neon at 30 Pa. The injected particle cloud consisted of monodisperse microparticles. A scanning laser sheet and a camera were used to determine the particle position in 3D. The observed cylindrical-shaped particle cloud showed an ordered structure with a distinct outer particle shell. The observations are in agreement with performed molecular dynamics simulations.

  6. Low pressure arc discharges with hollow cathodes and their using in plasma generators and charged particle sources

    CERN Document Server

    Vintizenko, L G; Koval, N N; Tolkachev, V S; Lopatin, I V; Shchanin, P M

    2001-01-01

    Paper presents the results of investigation into arc discharges with a hollow cathode generating 10 sup 1 sup 0 -10 sup 1 sup 2 concentration gas-discharge plasma in essential (approx 1 m sup 3) volumes at low (10 sup - sup 2 -1 Pa) pressures and up to 200 A discharge currents. One studied design of discharge systems with heated and cold cathodes their peculiar features, presented the parameters of plasma generators and of charged particle sources based on arc discharges and discussed, as well, the problems of more rational application of those systems in the processes for surface modification of solids

  7. Experimental study of a very high frequency, 162 MHz, segmented electrode, capacitively coupled plasma discharge

    Science.gov (United States)

    Sirse, Nishant; Harvey, Cleo; Gaman, Cezar; Ellingboe, Bert

    2016-09-01

    Radio-frequency capacitively coupled plasma (CCP) discharge operating at a very high frequency, 30-300 MHz, offers many advantages over standard 13.56 MHz CCP. However, there is a limited flexibility on the choice of driving frequency and substrate size due to plasma non-uniformity caused by the standing wave effect and edge effect. To overcome this issue segmented electrode CCP's are proposed and researched. Despite its numerous advantages the power coupling mechanism and plasma chemistry in this type of discharge are not fully understood due to lack of experimental data. In this paper, we present the experimental study of a segmented electrode, 3x4 tile array (10x10 cm square tile with 1 cm tile-to-tile separation), CCP discharge driven at 162 MHz. We measured plasma uniformity and gas temperature using hairpin probe and optical emission spectroscopy respectively. A homemade RF compensated Langmuir probe is employed to measure the Electron Energy Distribution Function (EEDF) by second harmonic technique. Energy resolved quadrupole mass spectrometer is utilized to measure the ion energy distribution. Discharge/plasma properties are investigated for several operating conditions and for power coupling mode in both washer board and checker board configuration. The experimental results show that the uniform plasma density can be maintained over a large area along with highly non-equilibrium condition to produce unique gas phase plasma chemistry.

  8. Gas-discharge sources with charged particle emission from the plasma of glow discharge with a hollow cathode

    CERN Document Server

    Semenov, A P

    2001-01-01

    One studied properties of a magnetron discharge with a cold hollow and uncooled rod cathodes. One demonstrated the dominant effect of thermoelectron emission of a rod cathode heated in a discharge on characteristics of discharge and on emission properties of a gas-discharge plasma and the possibility pf a smooth transition of glow discharge to diffusion mode of arc discharge combustion. Paper describes sources of ions and electrons with improved physical and generalized design and engineering parameters. One shows the promise of the electrode structure of a hollow cathode magnetron discharge to be used as a source, in particular, of the atomic hydrogen and of atom flow of a working rod cathode

  9. Plasma chemistry in electron-beam sustained discharges

    Science.gov (United States)

    Turner, Miles

    2016-09-01

    There are many emerging applications that exploit the exotic chemical characteristics of plasmas. Some of these applications, if deployed on an industrial scale, involve processing much larger volumes of gas than seems reasonable using any atmospheric pressure plasma source in wide use today. We note that an electron-beam sustained discharge permits the creation of a atmospheric pressure plasma with reasonable uniformity, large volme, and widely controllable electron temperature. Robust and durable electron beam sources now exist that would facilitate such applications. In this paper we discuss the general advantages of this approach, and we present a modelling study concerned with the production of NO in mixtures of N2 and O2, looking towards plasma aided manufacturing of fertilizers.

  10. Dielectric barrier discharge plasma pretreatment on hydrolysis of microcrystalline cellulose

    Science.gov (United States)

    Fangmin, HUANG; Zhouyang, LONG; Sa, LIU; Zhenglong, Qin

    2017-04-01

    Dielectric barrier discharge (DBD) plasma was used as a pretreatment method for downstream hydrolysis of microcrystalline cellulose (MCC). The degree of polymerization (DP) of MCC decreased after it was pretreated by DBD plasma under a carrier gas of air/argon. The effectiveness of depolymerization was found to be influenced by the crystallinity of MCC when under the pretreatment of DBD plasma. With the addition of tert-butyl alcohol in the treated MCC water suspension solution, depolymerization effectiveness of MCC was inhibited. When MCC was pretreated by DBD plasma for 30 min, the total reducing sugar concentration (TRSC) and liquefaction yield (LY) of pretreated-MCC (PMCC) increased by 82.98% and 34.18% respectively compared with those for raw MCC.

  11. Dielectric barrier discharge plasma pretreatment on hydrolysis of microcrystalline cellulose

    Science.gov (United States)

    Huang, Fangmin; Long, Zhouyang; Liu, Sa; Qin, Zhenglong

    2017-04-01

    Dielectric barrier discharge (DBD) plasma was used as a pretreatment method for downstream hydrolysis of microcrystalline cellulose (MCC). The degree of polymerization (DP) of MCC decreased after it was pretreated by DBD plasma under a carrier gas of air/argon. The effectiveness of depolymerization was found to be influenced by the crystallinity of MCC when under the pretreatment of DBD plasma. With the addition of tert-butyl alcohol in the treated MCC water suspension solution, depolymerization effectiveness of MCC was inhibited. When MCC was pretreated by DBD plasma for 30 min, the total reducing sugar concentration (TRSC) and liquefaction yield (LY) of pretreated-MCC (PMCC) increased by 82.98% and 34.18% respectively compared with those for raw MCC.

  12. Dielectric barrier discharge plasma treatment of cellulose nanofibre surfaces

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Madsen, Bo; Berglund, Linn

    2017-01-01

    on the nanofibre surface. Ultrasonic irradiation further enhanced the wetting and oxidation of the nanofibre coating. Scanning electron microscopic observations showed skeleton-like features on the plasma-treated surface, indicating preferential etching of weaker domains, such as low-molecular weight domains......Dielectric barrier discharge plasma treatment was applied to modify cellulose nanofibre (CNF) surfaces with and without ultrasonic irradiation. The plasma treatment improved the wetting by deionised water and glycerol, and increased the contents of oxygen, carbonyl group, and carboxyl group...... and amorphous phases. Ultrasonic irradiation also improved the uniformity of the treatment. Altogether, it is demonstrated that atmospheric pressure plasma treatment is a promising technique to modify the CNF surface before composite processing....

  13. Generation of uniform atmospheric pressure argon glow plasma by dielectric barrier discharge

    Indian Academy of Sciences (India)

    Raju Bhai Tyata; Deepak Prasad Subedi; Rajendra Shrestha; Chiow San Wong

    2013-03-01

    In this paper, atmospheric pressure glow discharges (APGD) in argon generated in parallel plate dielectric barrier discharge system is investigated by means of electrical and optical measurements. Using a high voltage (0–20 kV) power supply operating at 10–30 kHz, homogeneous and steady APGD has been observed between the electrodes with gap spacing from 0.5 mm to 2 mm and with a dielectric barrier of thickness 2 mm while argon gas is fed at a controlled flow rate of 11/min. The electron temperature and electron density of the plasma are determined by means of optical emission spectroscopy. Our results show that the electron density of the discharge obtained is of the order of 1016 cm-3 while the electron temperature is estimated to be 0.65 eV. The important result is that electron density determined from the line intensity ratio method and stark broadening method are in very good agreement. The Lissajous figure is used to estimate the energy deposited to the glow discharge. It is found that the energy deposited to the discharge is in the range of 20 to 25 $\\$J with a discharge voltage of 1.85 kV. The energy deposited to the discharge is observed to be higher at smaller gas spacing. The glow discharge plasma is tested to be effective in reducing the hydrophobicity of polyethylene film significantly.

  14. A Study of DC Surface Plasma Discharge in Absence of Free Airflow: Ionic Wind Velocity Profile

    Directory of Open Access Journals (Sweden)

    M. Rafika

    2009-01-01

    Full Text Available In our study we are interested with the DC (Direct Current electric corona discharge created between two wire electrodes. We present experimental results related to some electroaerodynamic actuators based on the DC corona discharge at the surface of a dielectric material. We used different geometrical forms of dielectric surface such as a plate, a cylinder and a wing of aircraft of type NACA 0015. We present the current density-electric filed characteristics for different cases in order to determine the discharge regimes. The corona discharge produces non-thermal plasma so that it is called plasma discharge. Plasma discharge creates a tangential ionic wind above the surface at the vicinity of the wall. We have measured the ionic wind induced by the corona discharge in absence of free external airflow, we give the ionic wind velocity profiles for different surface forms and we compare the actuators effect based on the span of the ionic wind velocity values. We notice that the maximum ionic wind velocity is obtained with the NACA profile, which shows the effectiveness of this actuator for the airflow control.

  15. Effects of Gas Flow Rate on the Discharge Characteristics of a DC Excited Plasma Jet

    Science.gov (United States)

    Li, Xuechen; Jia, Pengying; Di, Cong; Bao, Wenting; Zhang, Chunyan

    2015-09-01

    A direct current (DC) source excited plasma jet consisting of a hollow needle anode and a plate cathode has been developed to form a diffuse discharge plume in ambient air with flowing argon as the working gas. Using optical and electrical methods, the discharge characteristics are investigated for the diffuse plasma plume. Results indicate that the discharge has a pulse characteristic, under the excitation of a DC voltage. The discharge pulse corresponds to the propagation process of a plasma bullet travelling from the anode to the cathode. It is found that, with an increment of the gas flow rate, both the discharge plume length and the current peak value of the pulsed discharge decrease in the laminar flow mode, reach their minima at about 1.5 L/min, and then slightly increase in the turbulent mode. However, the frequency of the pulsed discharge increases in the laminar mode with increasing the argon flow rate until the argon flow rate equals to about 1.5 L/min, and then slightly decreases in the turbulent mode. supported by National Natural Science Foundation of China (Nos. 10805013, 11375051), Funds for Distinguished Young Scientists of Hebei Province, China (No. A2012201045), Department of Education for Outstanding Youth Project of China (No. Y2011120), and Youth Project of Hebei University of China (No. 2011Q14)

  16. Delay time for the onset of beam plasma discharge

    Science.gov (United States)

    Parish, J. L.; Denig, W. F.; Raitt, W. J.

    1987-01-01

    The interaction of a nonrelativistic electron beam with a neutral gas in a large chamber is considered, and the time interval before ignition of beam plasma discharge (BPD) is studied. A new theoretical expression for the time delay before BPD ignition is found as a function of the critical current necessary for BPD to be established. There are two parameters in the theoretical expression, and both are derived from two different experiments. These parameters are used to write the time evolution equation for plasma density as a function of time.

  17. Differential Inactivation of Fungal Spores in Water and on Seeds by Ozone and Arc Discharge Plasma.

    Directory of Open Access Journals (Sweden)

    Min Ho Kang

    Full Text Available Seed sterilization is essential for preventing seed borne fungal diseases. Sterilization tools based on physical technologies have recently received much attention. However, available information is very limited in terms of efficiency, safety, and mode of action. In this study, we have examined antifungal activity of ozone and arc discharge plasma, potential tools for seed sterilization. In our results, ozone and arc discharge plasma have shown differential antifungal effects, depending on the environment associated with fungal spores (freely submerged in water or infected seeds. Ozone inactivates Fusarium fujikuroi (fungus causing rice bakanae disease spores submerged in water more efficiently than arc discharge plasma. However, fungal spores associated with or infecting rice seeds are more effectively deactivated by arc discharge plasma. ROS generated in water by ozone may function as a powerful fungicidal factor. On the other hand, shockwave generated from arc discharge plasma may have greatly contributed to antifungal effects on fungus associated with rice seeds. In support of this notion, addition of ultrasonic wave in ozone generating water has greatly increased the efficiency of seed disinfection.

  18. Differential Inactivation of Fungal Spores in Water and on Seeds by Ozone and Arc Discharge Plasma

    Science.gov (United States)

    Kang, Min Ho; Pengkit, Anchalee; Choi, Kihong; Jeon, Seong Sil; Choi, Hyo Won; Shin, Dong Bum; Choi, Eun Ha; Uhm, Han Sup; Park, Gyungsoon

    2015-01-01

    Seed sterilization is essential for preventing seed borne fungal diseases. Sterilization tools based on physical technologies have recently received much attention. However, available information is very limited in terms of efficiency, safety, and mode of action. In this study, we have examined antifungal activity of ozone and arc discharge plasma, potential tools for seed sterilization. In our results, ozone and arc discharge plasma have shown differential antifungal effects, depending on the environment associated with fungal spores (freely submerged in water or infected seeds). Ozone inactivates Fusarium fujikuroi (fungus causing rice bakanae disease) spores submerged in water more efficiently than arc discharge plasma. However, fungal spores associated with or infecting rice seeds are more effectively deactivated by arc discharge plasma. ROS generated in water by ozone may function as a powerful fungicidal factor. On the other hand, shockwave generated from arc discharge plasma may have greatly contributed to antifungal effects on fungus associated with rice seeds. In support of this notion, addition of ultrasonic wave in ozone generating water has greatly increased the efficiency of seed disinfection. PMID:26406468

  19. Second-harmonic plasma response in diffusion-controlled surface-wave-sustained discharges

    Science.gov (United States)

    Stoev, L.

    2008-05-01

    The formation of nonlinear plasma response at the second harmonic frequency in diffusion controlled surface-wave-sustained discharges is studied theoretically. The study is aimed at estimating theoretically the ratio of the squared amplitudes of the wave field of fundamental frequency and of the resulting - from the nonlinear effects - electric field at the second harmonic frequency. The model presented is intended for further use in discharge diagnostics.

  20. Cold-cathode, pulsed-power plasma discharge switch

    Science.gov (United States)

    Goebel, Dan M.

    1996-09-01

    CROSSATRONTMmodulator switches are cold-cathode, grid-controlled, plasma-discharge devices that are used for thyratron and hard-tube replacement in high-voltage, pulsed-power applications. CROSSATRON modulator switches have been used to produce square pulses of up to 100 kV and 1000 A, and CROSSATRON laser-discharge switches have switched peak discharge currents of up to 10 kA at 40 kV. The major advantage that CROSSATRON switches offer over other plasma switches is a rapid deionization time that permits high pulse-repetition frequencies (103 to 106 pulses per second depending on the application), and a long life associated with the cold-cathode plasma production mechanism. Compared to hard tubes, CROSSATRON switches have a relatively low forward voltage drop (500 V), the ability to close and open up to 1 kA of peak current, and lower grid-drive power requirements. In this article, we describe the physical mechanisms for how the switch works based on simple models and experimental data. The design of CROSSATRON switches is explained, and characteristic performance in closing and opening applications is described and explained.

  1. Research on soft x-rays in high-current plasma-focus discharges and estimation of plasma electron temperature

    Science.gov (United States)

    Skladnik-Sadowska, E.; Zaloga, D.; Sadowski, M. J.; Kwiatkowski, R.; Malinowski, K.; Miklaszewski, R.; Paduch, M.; Surala, W.; Zielinska, E.; Tomaszewski, K.

    2016-09-01

    The paper presents results of experimental studies of dense and high-temperature plasmas, which were produced by pulsed high-current discharges within a modernised PF-1000U facility operated at different initial gas conditions, and supplied from a condenser bank which delivered energy of about 350 kJ. The investigated discharges were performed at the initial deuterium filling under pressure of 1.6-2.0 hPa, with or without an additional puffing of pure deuterium (1 cm3, under pressure 0.15 MPa, at instants 1.5-2 ms before the main discharge initiation). For a comparison discharges were also performed at the initial neon filling under pressure of 1.1-1.3 hPa, with or without the addition of deuterium puffing. The recorded discharge current waveforms, laser interferometric images, signals of hard x-rays and fusion neutrons, as well as time-integrated x-ray pinhole images and time-resolved x-ray signals were compared. From a ratio of the x-ray signals recorded behind beryllium filters of different thickness there were estimated values of a plasma electron temperature (T e) in a region at the electrode outlets. For pure deuterium discharges an averaged T e value amounted to 150-170 eV, while for neon discharges with the deuterium puffing it reached 330-880 eV (with accuracy of  ±20%).

  2. Dielectric barrier discharge plasma actuator for flow control

    Science.gov (United States)

    Opaits, Dmitry Florievich

    Electrohydrodynamic (EHD) and magnetohydrodynamic phenomena are being widely studied for aerodynamic applications. The major effects of these phenomena are heating of the gas, body force generation, and enthalpy addition or extraction, [1, 2, 3]. In particular, asymmetric dielectric barrier discharge (DBD) plasma actuators are known to be effective EHD device in aerodynamic control, [4, 5]. Experiments have demonstrated their effectiveness in separation control, acoustic noise reduction, and other aeronautic applications. In contrast to conventional DBD actuators driven by sinusoidal voltages, we proposed and used a voltage profile consisting of nanosecond pulses superimposed on dc bias voltage. This produces what is essentially a non-self-sustained discharge: the plasma is generated by repetitive short pulses, and the pushing of the gas occurs primarily due to the bias voltage. The advantage of this non-self-sustained discharge is that the parameters of ionizing pulses and the driving bias voltage can be varied independently, which adds flexibility to control and optimization of the actuators performance. Experimental studies were conducted of a flow induced in a quiescent room air by a single DBD actuator. A new approach for non-intrusive diagnostics of plasma actuator induced flows in quiescent gas was proposed, consisting of three elements coupled together: the Schlieren technique, burst mode of plasma actuator operation, and 2-D numerical fluid modeling. During the experiments, it was found that DBD performance is severely limited by surface charge accumulation on the dielectric. Several ways to mitigate the surface charge were found: using a reversing DC bias potential, three-electrode configuration, slightly conductive dielectrics, and semi conductive coatings. Force balance measurements proved the effectiveness of the suggested configurations and advantages of the new voltage profile (pulses+bias) over the traditional sinusoidal one at relatively low

  3. Investigation of Atmospheric Plasma Discharge and Its Application to Surface Modification of Textile Materials

    Institute of Scientific and Technical Information of China (English)

    TANG Xiao-liang; QIU Gao; FENG Xian-ping; YAN Yong-hui; SHI Yun-cheng; YAN Zhi-ren; WANG Liang

    2005-01-01

    In this paper, an improved quasi-stable atmospheric pressure dielectric barrier discharge (DBD) plasma source is achieved after carefully controlled discharge voltage and current, discharge power, working gas, treatment period,and gap between the electrodes. This plasma source has been used to modify the surface of Polybutylene Terephthalate (PBT) melt-blown nonwovens and Polyester(PET) fabrics, and the various influences on surface modification and the aging effeet of treated polymeric materials have been systematically investigated. In addition, the method of spectrum analysis is also used for diagnosing plasma parameters such as electron temperature.Experimental results indicate that both the wettablity and permeation of treated PBT melt-blown nonwovens and dyeing ability of treated PET fabrics are certainly improved.

  4. Inactivation of Escherichia Coli Using Remote Low Temperature Glow Discharge Plasma

    Institute of Scientific and Technical Information of China (English)

    HU Miao; CHEN Jierong; CHEN Chua

    2008-01-01

    Low-temperature plasma is distinguished as a developing approach for sterilization which can deal with and overcome those problems such as thermal sensitivity and destruction by heat,formation of toxic by-products,higher costs and inefficiency in performances,caused by conventional methods.In this study,an experimental investigation was undertaken to characterize the effects of the operational parameters,such as treating time,discharge power and gas flow rate,of remote glow discharge air plasma.The results show that the inactivation of Escherichia coli can reach above 99.99% in less than 60 seconds and the optimal operational conditions for treating time,discharge power and gas flow rate were:40 s,80 W and 60 cm3/min,respectively.The contribution of UV radiation during plasma germ deactivation is very limited.

  5. Laser-induced optogalvanic signal oscillations in miniature neon glow discharge plasma.

    Science.gov (United States)

    Saini, V K

    2013-06-20

    Laser-induced optogalvanic (OG) signal oscillations detected in miniature neon glow discharge plasma are investigated using a discharge equivalent-circuit model. The damped oscillations in OG signal are generated when a pulsed dye laser is tuned to a specific neon transition (1s5→2p2) at 588.2 nm under the discharge conditions where dynamic resistance changes its sign. Penning ionization via quasi-resonant energy transfer collisions between neon gas atoms in metastable state and sputtered electrode atoms in ground state is discussed to explain the negative differential resistance properties of discharge plasma that are attributed to oscillations in the OG signal. The experimentally observed results are simulated by analyzing the behavior of an equivalent discharge-OG circuit. Good agreement between theoretically calculated and experimental results is observed. It is found that discharge plasma is more sensitive and less stable in close vicinity to dynamic resistance sign inversion, which can be useful for weak-optical-transition OG detection.

  6. Evaluation and Optimization of Electrode Configuration of Multi-Channel Corona Discharge Plasma for Dye-Containing Wastewater Treatment

    Science.gov (United States)

    Ren, Jingyu; Wang, Tiecheng; Qu, Guangzhou; Liang, Dongli; Hu, Shibin

    2015-12-01

    A discharge plasma reactor with a point-to-plane structure was widely studied experimentally in wastewater treatment. In order to improve the utilization efficiency of active species and the energy efficiency of this kind of discharge plasma reactor during wastewater treatment, the electrode configuration of the point-to-plane corona discharge reactor was studied by evaluating the effects of discharge spacing and adjacent point distance on discharge power and discharge energy density, and then dye-containing wastewater decoloration experiments were conducted on the basis of the optimum electrode configuration. The experimental results of the discharge characteristics showed that high discharge power and discharge energy density were achieved when the ratio of discharge spacing to adjacent point distance (d/s) was 0.5. Reactive Brilliant Blue (RBB) wastewater treatment experiments presented that the highest RBB decoloration efficiency was observed at d/s of 0.5, which was consistent with the result obtained in the discharge characteristics experiments. In addition, the biodegradability of RBB wastewater was enhanced greatly after discharge plasma treatment under the optimum electrode configuration. RBB degradation processes were analyzed by GC-MS and IC, and the possible mechanism for RBB decoloration was also discussed. supported by China's Postdoctoral Science Foundation (No. 2014M562460), the Initiative Funding Programs for Doctoral Research of Northwest A&F University (No. 2013BSJJ121), and National Natural Science Foundation of China (No. 21107085)

  7. Instability Parameters of Optical Oscillation Frequency in Plasma Central Discharge and Periphery Region

    Institute of Scientific and Technical Information of China (English)

    ZHOU Zhu-Wen; M.A.LIEBERMAN; Sungjin KIM

    2006-01-01

    @@ We have observed relaxation oscillations in a capacitive discharge in Ar gas, connected to a peripheral ground chamber. The plasma oscillations observed from time-varying optical emission from the main discharge chamber show, for example, a high frequency (75.37kHz) relaxation oscillation, at 100mTorr and 8 W absorbed power,and a low frequency (2.72 Hz) relaxation oscillation, 100mTorr and 325 W absorbed power. Time-varying optical emission intensity and plasma density are also detected with a Langmuir probe. The theoretical result agrees well with experiments.

  8. Quantitative Analysis on Carbon Migration in Double-Glow Discharge Plasma Surface Alloying Process

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhen-xia; WANG Cong-zeng; ZHANG Wen-quan; SU Xue-kuan

    2004-01-01

    Carbon migration is of great significance in double-glow discharge plasma surface alloying process, but literature of quantitative analysis about carbon migration is relatively scarce. In this paper differential equations of the carbon and metal concentration distribution were established. By means of differential equations carbon migration was described and a numerical solution was acquired. The computational results fit the experiment results quite well.

  9. Experimental results of breakdown in "Dena" plasma focus device

    Science.gov (United States)

    Goudarzi, Shervin; Hoseinian, S. M.; Raeisdana, A.

    2014-06-01

    In spite of the intense research activities on Plasma Focus devices, the physics of the initial breakdown and surface discharge phase has not been realized completely. In this paper we have analyzed the surface discharge and initial breakdown phase in Filippov-type Plasma Focus Facility "Dena" (90 kJ, 25 kV) on the base of the current and current derivative measured signals by using Argon, Neon and Krypton as working gases at different discharge voltages and gas pressures, and the effects of working conditions (atomic weight, discharge voltage and gas pressure) on the breakdown and surface discharge phase have expressed. Also, on the base of these results, we have investigated about the relation of this phase with final pinch phase.

  10. Dielectric barrier discharge plasma induced degradation of aqueous atrazine.

    Science.gov (United States)

    Feng, Jingwei; Jiang, Lin; Zhu, Dan; Su, Kuizu; Zhao, Dayong; Zhang, Jibiao; Zheng, Zheng

    2016-05-01

    Degradation of herbicide atrazine in aqueous solution was investigated using a plate type dielectric barrier discharge (DBD) plasma reactor. DBD plasma was generated at the gas-liquid interface of the formed water film. At discharge time of 14 min, atrazine was degradated effectively with a degradation rate of 99 % at the discharge power of 200 W. The experimental data fitted well with first-order kinetics and the energy efficiency for 90 % degradation of atrazine (G value) was calculated, obtaining a rate constant of 0.35 min(-1) and a G value of 1.27 × 10(-10) mol J(-1) (98.76 mg kW(-1) h(-1)) at a discharge power of 200 W, respectively. The addition of Fe(2+) increased the rate constant and G value dramatically, and a significant decrease of the rate constant and G value was observed with the addition of radical scavengers (tert-butyl alcohol, isopropyl alcohol, or Na2CO3). The generated aqueous O3 and H2O2 were determined, which promoted the degradation of herbicide atrazine. Dechlorination was observed and the experimentally detected Cl(-) was 1.52 mg L(-1) at a discharge time of 14 min. The degradation intermediates of atrazine were detected by means of liquid chromatography-mass spectrometry; dechlorination, hydroxylation, dealkylation, and alkyl oxidation processes were involved in the degradation pathways of atrazine.

  11. Effects of background gas on sulfur hexafluoride removal by atmospheric dielectric barrier discharge plasma

    Science.gov (United States)

    Zhang, Xiaoxing; Xiao, Hanyan; Hu, Xiongxiong; Gui, Yingang

    2016-11-01

    The effects of background gases (He, Ar, N2 and air) on SF6 removal in a dielectric barrier reactor were investigated at atmospheric pressure. A comparison among these background gases was performed in terms of discharge voltage, discharge power, mean electron energy, electron density, removal efficiency and energy yield for the destruction of SF6. Results showed that the discharge voltage of He and Ar was lower than that of N2 and air, but the difference of their discharge power was small. Compared with three other background gases, Ar had a relatively superior destruction and removal rate and energy yield since the mean electron energy and electron density in SF6/H2O/Ar plasma were both maintained at a high level. Complete removal of 2% SF6 could be achieved at a discharge power of 48.86 W with Ar and the corresponding energy yield can reach 4.8 g/kWh.

  12. Effects of background gas on sulfur hexafluoride removal by atmospheric dielectric barrier discharge plasma

    Directory of Open Access Journals (Sweden)

    Xiaoxing Zhang

    2016-11-01

    Full Text Available The effects of background gases (He, Ar, N2 and air on SF6 removal in a dielectric barrier reactor were investigated at atmospheric pressure. A comparison among these background gases was performed in terms of discharge voltage, discharge power, mean electron energy, electron density, removal efficiency and energy yield for the destruction of SF6. Results showed that the discharge voltage of He and Ar was lower than that of N2 and air, but the difference of their discharge power was small. Compared with three other background gases, Ar had a relatively superior destruction and removal rate and energy yield since the mean electron energy and electron density in SF6/H2O/Ar plasma were both maintained at a high level. Complete removal of 2% SF6 could be achieved at a discharge power of 48.86 W with Ar and the corresponding energy yield can reach 4.8 g/kWh.

  13. ROS/RNS Production in Water Using Various Discharge Plasma

    Science.gov (United States)

    Takahashi, Kazuhiro; Satoh, Kohki; Itoh, Hidenori; Kawaguchi, Hideki; Timoshkin, Igor; Given, Martin; MacGregor, Scott

    2015-09-01

    A pulsed discharge, a DC corona discharge and an atmospheric pressure plasma jet are generated above water, the off-gas of a packed-bed dielectric barrier discharge (PB-DBD) is sparged into water, and then reactive oxygen species and reactive nitrogen species in the water are investigated. H2O2, NO3- and a trace of NO2- are produced in the water after the plasma exposure. H2O2 concentration decreases when NO3- concentration increases, so that this is likely that OH radical to produce H2O2 by OH + OH -->H2O2 is consumed in the NO3- production by NO2 + OH --> HNO3 --> NO3-+ H+ (in water). Since no species is detected in water by the sparging of the PB-DBD off-gas containing more than 1000 ppm of O3, O3 does not contribute to produce H2O2 in water. Further, only NO3- is produced by the sparging of the off-gas containing N2O5 and HNO3. This leads that H2O2 and NO2- can be produced by short-lifetime species in plasma. In this work, the highest generation efficiency of H2O2 and NO2- are respectively 3,820 μg/Wh and 830 μg/Wh by the pulsed-plasma exposure, and that of NO3- is 2,530 μg/Wh by the off-gas sparging of the PB-DBD.

  14. Radiative heat transfer in plasma of pulsed high pressure caesium discharge

    Science.gov (United States)

    Lapshin, V. F.

    2016-01-01

    Two-temperature many component gas dynamic model is used for the analysis of features of radiative heat transfer in pulsed high pressure caesium discharge plasma. It is shown that at a sufficiently high pressure the radial optical thickness of arc column is close to unit (τR (λ) ∼ 1) in most part of spectrum. In this case radiative heat transfer has not local character. In these conditions the photons which are emitted in any point of plasma volume are absorbed in other point remote from an emission point on considerable distance. As a result, the most part of the electric energy put in the discharge mainly near its axis is almost instantly redistributed on all volume of discharge column. In such discharge radial profiles of temperature are smooth. In case of low pressure, when discharge plasma is optically transparent for own radiation in the most part of a spectrum (τR(λ) << 1), the emission of radiation without reabsorption takes place. Radiative heat transfer in plasma has local character and profiles of temperature have considerable gradient.

  15. Plasma processes in water under effect of short duration pulse discharges

    Science.gov (United States)

    Gurbanov, Elchin

    2013-09-01

    It is very important to get a clear water without any impurities and bacteria by methods, that don't change the physical and chemical indicators of water now. In this article the plasma processes during the water treatment by strong electric fields and short duration pulse discharges are considered. The crown discharge around an electrode with a small radius of curvature consists of plasma leader channels with a high conductivity, where the thermo ionization processes and UV-radiation are taken place. Simultaneously the partial discharges around potential electrode lead to formation of atomic oxygen and ozone. The spark discharge arises, when plasma leader channels cross the all interelectrode gap, where the temperature and pressure are strongly grown. As a result the shock waves and dispersing liquid streams in all discharge gap are formed. The plasma channels extend, pressure inside it becomes less than hydrostatic one and the collapse and UV-radiation processes are started. The considered physical processes can be successfully used as a basis for development of pilot-industrial installations for conditioning of drinking water and to disinfecting of sewage.

  16. Investigation of dielectric barrier discharge plasma flow control

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Effects of plasma flow control are researched on the basis of plasma exciting flow experiments and numerical simulations. Turbulent model is more effective than laminar model in plasma numerical simulation as results showed. Both plasma exciting effects of acceleration and flow separation suppression are investigated through experiments carried on the flat plate and the compressor cascades. The results demonstrate that boundary layer characteristic is modified by plasma exciting. Distributions of total pressure and velocity in the wake are improved notably for 20 m/s coming velocity and the effect of plasma can still be observed while velocity is increased to 50 m/s. For low velocity flow, plasma exciting is effective in flow separation suppression.

  17. Discharge and optical characterizations of nanosecond pulse sliding dielectric barrier discharge plasma for volatile organic compound degradation

    Science.gov (United States)

    Jiang, Nan; Guo, Lianjie; Shang, Kefeng; Lu, Na; Li, Jie; Wu, Yan

    2017-04-01

    In this work, a nanosecond bipolar pulsed voltage coupled with a negative DC component is employed to generate sliding dielectric barrier discharge (DBD) plasma in a three-electrode geometry reactor and improve volatile organic compound (VOC) degradation at room temperature. The effects of the bipolar pulsed voltage (U ±pulse) and negative DC voltage (U ‑DC) on the discharge characteristic, optical characteristic, plasma gas temperature (T gas), and vibrational temperature (T vib) are discussed. The horizontal distribution characteristics of the N2(C3Πu  →  B3Πg) emission intensity, T gas, and T vib are also investigated to understand the propagation mechanism of sliding DBD along the dielectric surface. The experimental results reveal that a negative DC component applied to a third electrode can extend the plasma extension region, indicating that the gas ionization is ignited by the nanosecond high-voltage pulse, while charge drift is forced by the surface potential difference caused by the negative high-voltage DC. The T gas is measured by optical emission spectroscopy related to the rotational bands of N2(C3 Πu  →  B3Πg), and is approximately 375  ±  5 K under the condition of U ±pulse  =  20 kV and U ‑DC  =  ‑20 kV. Compared with typical surface DBD plasma, sliding DBD plasma is quasi-diffusive and distributed more uniformly within the whole discharge gap. Furthermore, both surface DBD and sliding DBD are used for removing toluene from flowing air. It is found that sliding DBD has higher toluene degradation efficiency and energy yield than surface DBD when they are excited by the positive pulsed voltage (U +pulse).

  18. Carbon dioxide splitting in a dielectric barrier discharge plasma: a combined experimental and computational study.

    Science.gov (United States)

    Aerts, Robby; Somers, Wesley; Bogaerts, Annemie

    2015-02-01

    Plasma technology is gaining increasing interest for the splitting of CO2 into CO and O2 . We have performed experiments to study this process in a dielectric barrier discharge (DBD) plasma with a wide range of parameters. The frequency and dielectric material did not affect the CO2 conversion and energy efficiency, but the discharge gap can have a considerable effect. The specific energy input has the most important effect on the CO2 conversion and energy efficiency. We have also presented a plasma chemistry model for CO2 splitting, which shows reasonable agreement with the experimental conversion and energy efficiency. This model is used to elucidate the critical reactions that are mostly responsible for the CO2 conversion. Finally, we have compared our results with other CO2 splitting techniques and we identified the limitations as well as the benefits and future possibilities in terms of modifications of DBD plasmas for greenhouse gas conversion in general.

  19. Streptococci biofilm decontamination on teeth by low-temperature air plasma of dc corona discharges

    Science.gov (United States)

    Kovalóvá, Z.; Zahoran, M.; Zahoranová, A.; Machala, Z.

    2014-06-01

    Non-thermal plasmas of atmospheric pressure air direct current corona discharges were investigated for potential applications in dental medicine. The objective of this ex vivo study was to apply cold plasmas for the decontamination of Streptococci biofilm grown on extracted human teeth, and to estimate their antimicrobial efficiency and the plasma's impact on the enamel and dentine of the treated tooth surfaces. The results show that both positive streamer and negative Trichel pulse coronas can reduce bacterial population in the biofilm by up to 3 logs in a 10 min exposure time. This bactericidal effect can be reached faster (within 5 min) by electrostatic spraying of water through the discharge onto the treated tooth surface. Examination of the tooth surface after plasma exposure by infrared spectroscopy and scanning electron microscopy did not show any significant alteration in the tooth material composition or the tooth surface structures.

  20. Plasma Kinetics in the Ethanol/Water/Air Mixture in "Tornado" Type Electrical Discharge

    CERN Document Server

    Levko, D; Chernyak, V; Olszewski, S; Nedybaliuk, O

    2011-01-01

    This paper presents the results of a theoretical and experimental study of plasma-assisted reforming of ethanol into molecular hydrogen in a new modification of the "tornado" type electrical discharge. Numerical modeling clarifies the nature of the non-thermal conversion and explains the kinetic mechanism of nonequilibrium plasma-chemical transformations in the gas-liquid system and the evolution of hydrogen during the reforming as a function of discharge parameters and ethanol-to-water ratio in the mixture. We also propose a scheme of chemical reactions for plasma kinetics description. It is shown that some characteristics of the investigated reactor are at least not inferior to characteristics of other plasma chemical reactors.

  1. Study on electrolytic plasma discharging behavior and its influence on the plasma electrolytic oxidation coatings

    Science.gov (United States)

    Hussein, Riyad Omran

    In this study, aluminum oxide was deposited on a pure aluminum substrate to produce hard ceramic coatings using a Plasma Electrolytic Oxidation (PEO) process. The process utilized DC, unipolar pulsed DC in the frequency range (0.2 KHz -- 20 KHz) and bipolar pulsed DC current modes. The effects of process parameters (i.e., electrolyte concentration, current density and treatment time) on the plasma discharge behavior during the PEO treatment were investigated using optical emission spectroscopy (OES) in the visible and near ultraviolet (NUV) band (285 nm -- 900 nm). The emission spectra were recorded and plasma temperature profile versus processing time was constructed using the line intensity ratios method. Scanning Electron Microscopy (SEM) with energy dispersive x-ray analysis (EDS) was used to study the coating microstructure. It was found that the plasma discharge behavior significantly influenced the microstructure and the morphology of the oxide coatings. The main effect came from the strongest discharges which were initiated at the interface between the substrate and the coating. Through manipulation of process parameters to control or reduce the strongest discharge, the density and quality of the coating layers could be modified. This work demonstrated that by adjusting the ratio of the positive to negative pulse currents as well as their timing in order to eliminate the strongest discharges, the quality of the coatings was considerably improved.

  2. Electric plasma discharge combustion synthesis of chlorine dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Dotson, R. L.; Geren, G. W.

    1984-09-18

    A process for the production of chlorine dioxide comprises feeding an inert gas to a reaction zone and applying an electrical discharge to the inert gas to produce a high temperature plasma. Chlorine gas and oxygen gas are supplied simultaneously to the reaction zone and reacted in the plasma to produce a gaseous mixture comprised of chlorine dioxide, chlorine, oxygen and inert gas, the molar ratio of oxygen to chlorine in the reaction zone being at least about 2.5;1. The gaseous mixture is recovered from the reaction zone. Chlorine dioxide, which may be recovered as a gas or reacted to produce an alkali metal chlorite, is employed as a bleaching agent and a water treatment agent.

  3. Electrical discharges of plasma ozonizer and its application

    Directory of Open Access Journals (Sweden)

    Tirawanichakul, S.

    2007-05-01

    Full Text Available Ozone synthesis is one of the applications of near atmospheric plasma processing. An ozone generator in this research comprised two annular cylindrical-shaped electrodes. The inner electrode was made ofstainless steel covered with the dielectric glass and the outer electrode was also made of stainless steel. The electric spacing gap was 0.0075 m and length of ozonizer was 0.21 m. Oxygen gas passing through thedischarge gap between two electrodes supplied by an alternating current (AC high voltage power supply, frequency 50 Hz, ranging of 6-10 kVAC was used for producing ozone. The amount of ozone was determinedby the KI standard method. The result showed that the concentration of ozone is proportional to the AC applied voltage. For determining effect of purified oxygen feed rate of 6-10 L/min on quantity of ozone, theresults indicated that at the volumetric flow rate of 8 L/min produced the largest amount of ozone. In addition, ozone concentration at a flow rate of 8 L/min and an electrical discharge time of 3 minutes wasapproximately determined as 41, 60, 80 and 135 mg/L at 8, 9, 10 and 11 kVAC, respectively. Moreover, study of dye wastewater of Krajud mat was proposed and treated by three different methods. Firstly, dye wastewater was solely treated by a plasma ozonation. Secondly, a combination ofozonation and alum coagulation was used for dye wastewater treatment. Finally, the combined ozonation and activated carbon adsorption were used for dye wastewater treatment. The experimental results showedthat the percentage of light absorbance reduction of pink dyed wastewater for these three different methods was about 56%, 35% and 10%, respectively compared to the reference sample. In addition, For thesemethods, the percentage of BOD of treated dye wastewater could be reduced to 64%, 54% and 46% respectively, the percentage of COD could be reduced to approximately 78%, 62% and 27%, respectively, comparedto the reference sample. In conclusion, the

  4. Dielectric Barrier Discharge Plasma Actuator for Flow Control

    Science.gov (United States)

    Opaits, Dmitry, F.

    2012-01-01

    This report is Part II of the final report of NASA Cooperative Agreement contract no. NNX07AC02A. It includes a Ph.D. dissertation. The period of performance was January 1, 2007 to December 31, 2010. Part I of the final report is the overview published as NASA/CR-2012- 217654. Asymmetric dielectric barrier discharge (DBD) plasma actuators driven by nanosecond pulses superimposed on dc bias voltage are studied experimentally. This produces non-self-sustained discharge: the plasma is generated by repetitive short pulses, and the pushing of the gas occurs primarily due to the bias voltage. The parameters of ionizing pulses and the driving bias voltage can be varied independently, which adds flexibility to control and optimization of the actuators performance. The approach consisted of three elements coupled together: the Schlieren technique, burst mode of plasma actuator operation, and 2-D numerical fluid modeling. During the experiments, it was found that DBD performance is severely limited by surface charge accumulation on the dielectric. Several ways to mitigate the surface charge were found: using a reversing DC bias potential, three-electrode configuration, slightly conductive dielectrics, and semi conductive coatings. Force balance measurements proved the effectiveness of the suggested configurations and advantages of the new voltage profile (pulses+bias) over the traditional sinusoidal one at relatively low voltages. In view of practical applications certain questions have been also addressed, such as electrodynamic effects which accompany scaling of the actuators to real size models, and environmental effects of ozone production by the plasma actuators.

  5. Experimental investigations of the plasma radial uniformity in single and dual frequency capacitively coupled argon discharges

    Science.gov (United States)

    Zhao, Kai; Liu, Yong-Xin; Gao, Fei; Liu, Gang-Hu; Han, Dao-Man; Wang, You-Nian

    2016-12-01

    In the current work, the radial plasma density has been measured by utilizing a floating double probe in single and dual frequency capacitively coupled argon discharges operated in a cylindrical reactor, aiming at a better understanding of electromagnetic effects and exploring a method of improving the radial uniformity. The experimental results indicate that for single-frequency plasma sustained at low pressure, the plasma density radial profile exhibits a parabolic distribution at 90 MHz, whereas at 180 MHz, the profile evolves into a bimodal distribution, and both cases indicate poor uniformities. With increasing the pressure, the plasma radial uniformity becomes better for both driving frequency cases. By contrast, when discharges are excited by two frequencies (i.e., 90 + 180 MHz), the plasma radial profile is simultaneously influenced by both sources. It is found that by adjusting the low-frequency to high-frequency voltage amplitude ratio β, the radial profile of plasma density could be controlled and optimized for a wide pressure range. To gain a better plasma uniformity, it is necessary to consider the balance between the standing wave effect, which leads to a maximum plasma density at the reactor center, and the edge field effect, which is responsible for a maximum density near the radial electrode edge. This balance can be controlled either by selecting a proper gas pressure or by adjusting the ratio β.

  6. Plasma sterilization of polyethylene terephthalate bottles by pulsed corona discharge at atmospheric pressure.

    Science.gov (United States)

    Masaoka, Satoshi

    2007-06-01

    A pulsed power supply was used to generate a corona discharge on a polyethylene terephthalate bottle, to conduct plasma sterilization at atmospheric pressure. Before generating such a discharge, minute quantities of water were attached to the inner surface of the bottle and to the surface of a high voltage (HV) electrode inserted into the bottle. Next, high-voltage pulses of electricity were discharged between electrodes for 6.0s, while rotating the bottle. The resulting spore log reduction values of Bacillus subtilis and Aspergillus niger on the inner surface of the bottle were 5.5 and 6 or higher, respectively, and those on the HV electrode surface were each 6 or higher for both strains. The presence of the by-products gaseous ozone, hydrogen peroxide, and nitric ions resulting from the electrical discharge was confirmed.

  7. Conversion from Dimethyl Ether to Dimethoxymethane and Dimethoxyethane Using Dielectric-Barrier Discharge Plasma

    Institute of Scientific and Technical Information of China (English)

    Wang Yu; Liu Changjun; Zhang Yueping

    2005-01-01

    Experimental investigation was conducted to convert dimethyl ether (DME) in thepresence of steam using dielectric barrier discharge (DBD) at atmospheric pressure and 373 K.The flow rate of DME was 20 ml/min. The introduction of steam resulted in an increase in theDME conversion and the selectivity of oxygenates. Plasma steam-enhanced dimethyl ether (DME)conversion led to a direct synthesis of DMMT and DMET, with a high selectivity of 5.78% and17.99%, respectively. The addition of steam promoted the formation of "plasma aerosol" that wasfavored for the formation of liquid oxygenates. The reaction pathway of plasma DME conversionwas proposed.

  8. Magnetohydrodynamic simulation of the inverse-pinch plasma discharge

    Science.gov (United States)

    Esaulov, A.; Bauer, B. S.; Lindemuth, I. R.; Makhin, V.; Presura, R.; Ryutov, D. D.; Sheehey, P. T.; Siemon, R. E.; Sotnikov, V. I.

    2004-04-01

    A wall confined plasma in an inverse-pinch configuration holds potential as a plasma target for Magnetized Target Fusion (MTF) as well as a simple geometry to study wall-confined plasma. An experiment is planned to study the inverse-pinch configuration using the Zebra Z pinch [B. S. Bauer et al., AIP Conference Proceedings Vol. 409 (American Institute of Physics, Melville, 1997), p. 153] of the Nevada Terawatt Facility at the University of Nevada, Reno (UNR). The dynamics of the discharge formation have been analyzed using analytic models and numerical methods. Strong heating occurs by thermalization of directed energy when an outward moving current sheet (the inverse pinch effect) collides with the outer wall of the experimental chamber. Two-dimensional magnetohydrodynamic simulations show Rayleigh-Taylor and Richtmyer-Meshkov like modes of instability, as expected because of the shock acceleration during plasma formation phase. The instabilities are not disruptive, but give rise to a mild level of turbulence. The conclusion from this work is that an interesting experiment relevant to wall confinement for MTF could be done using existing equipment at UNR.

  9. Radiative Characteristics of the Pulse-Periodic Discharge Plasma Initiated by Runaway Electrons

    Science.gov (United States)

    Lomaev, M. I.; Beloplotov, D. V.; Tarasenko, V. F.; Sorokin, D. A.

    2016-07-01

    Results of experimental investigations of amplitude-temporal and spectral characteristics of radiation of a pulse-periodic discharge plasma initiated in nitrogen by runaway electrons are presented. The discharge was initiated by high-voltage nanosecond voltage pulses with repetition frequency of 60 Hz in a sharply inhomogeneous electric field in a gap between the conic potential cathode and the planar grounded aluminum anode. It is established that intensive lines of Al I atoms and Al II atomic ions, lines of N I atoms and N II ions, bands of the first (1+) and second positive (2+) nitrogen systems, as well as bands of cyanogen CN are observed in the emission spectrum of the discharge plasma under the given excitation conditions.

  10. Three-dimensional discharge simulation of inductively coupled plasma (ICP) etching reactor

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    More and more importance has been attached to inductively coupled plasma (ICP) in semiconductor manufacture. For a deep understanding of the plasma discharge process in the etching reactor, this study made a three-dimensional simulation on the Ar plasma discharge process with the commercial software CFD-ACE, which is according to the real experiment conditions and data supplied by North Microelec-tronic Corporation. The error of the simulation results is in the range of ±20% with credibility. The numerical results show that the three-dimentional spatial distribu-tion of electron density is reduced from the chamber center to the wall. The distri-bution of electron density, electron temperature and power deposition is related to the shape and placement of the coil.

  11. Hydrogen production from dimethyl ether using corona discharge plasma

    Science.gov (United States)

    Zou, Ji-Jun; Zhang, Yue-Ping; Liu, Chang-Jun

    Dimethyl ether (DME), with its non-toxic character, high H/C ratio and high-energy volumetric density, is an ideal resource for hydrogen production. In this work, hydrogen production from the decomposition of DME using corona discharge has been studied. The corona discharge plasma decomposition was conducted at ambient conditions. The effects of dilution gas (argon), flow rate, frequency and waveforms on the DME decomposition were investigated. The addition of dilution gas can significantly increase the hydrogen production rate. The highest hydrogen production rate with the lowest energy consumption presents at the flow rate of 27.5 Nml min -1. AC voltage is more favored than DC voltage for the production of hydrogen with less energy input. The optimal frequency is 2.0 kHz. The hydrogen production rate is also affected by the input waveform and decreases as following: sinusoid triangular > sinusoid > ramp > square, whereas the sinusoid waveform shows the highest energy efficiency. The corona discharge decomposition of DME is leading to a simple, easy and convenient hydrogen production with no needs of catalyst and external heating.

  12. Non-thermal dielectric-barrier discharge plasma damages human keratinocytes by inducing oxidative stress

    Science.gov (United States)

    KIM, KI CHEON; PIAO, MEI JING; HEWAGE, SUSARA RUWAN KUMARA MADDUMA; HAN, XIA; KANG, KYOUNG AH; JO, JIN OH; MOK, YOUNG SUN; SHIN, JENNIFER H.; PARK, YEUNSOO; YOO, SUK JAE; HYUN, JIN WON

    2016-01-01

    The aim of this study was to identify the mechanisms through which dielectric-barrier discharge plasma damages human keratinocytes (HaCaT cells) through the induction of oxidative stress. For this purpose, the cells were exposed to surface dielectric-barrier discharge plasma in 70% oxygen and 30% argon. We noted that cell viability was decreased following exposure of the cells to plasma in a time-dependent manner, as shown by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The levels of intracellular reactive oxygen species (ROS) were determined using 2′,7′-dichlorodihydro-fluorescein diacetate and dihydroethidium was used to monitor superoxide anion production. Plasma induced the generation of ROS, including superoxide anions, hydrogen peroxide and hydroxyl radicals. N-acetyl cysteine, which is an antioxidant, prevented the decrease in cell viability caused by exposure to plasma. ROS generated by exposure to plasma resulted in damage to various cellular components, including lipid membrane peroxidation, DNA breaks and protein carbonylation, which was detected by measuring the levels of 8-isoprostane and diphenyl-1-pyrenylphosphine assay, comet assay and protein carbonyl formation. These results suggest that plasma exerts cytotoxic effects by causing oxidative stress-induced damage to cellular components. PMID:26573561

  13. Action of plasma jets of a low-current spark discharge on microorganisms ( Escherichia coli)

    Science.gov (United States)

    Baldanov, B. B.; Semenov, A. P.; Ranzhurov, Ts. V.; Nikolaev, E. O.; Gomboeva, S. V.

    2015-11-01

    High efficiency of bactericide action of cold argon plasma generated by plasma jets of a weak-current spark discharge under atmospheric pressure is demonstrated. It is found that an increase in the time of treatment with plasma jets from a low-current spark discharge makes it possible to effectively inactivate microorganisms over a much larger area.

  14. An overview of CO2 conversion in a microwave discharge: the role of plasma-catalysis

    Science.gov (United States)

    Chen, Guoxing; Britun, Nikolay; Godfroid, Thomas; Georgieva, Violeta; Snyders, Rony; Delplancke-Ogletree, Marie-Paule

    2017-03-01

    An overview of the recent progress on plasma-assisted CO2 conversion in microwave discharges is given. Special attention is devoted to the results obtained using plasma catalysis, which are compared to the plasma-only CO2 decomposition cases. The effects of plasma operating conditions, catalyst preparation methods, nature of plasma activation gas, gas mixture, as well as the NiO content on the TiO2 surface on CO2 conversion and its energy efficiency are discussed. A significant improvement in CO2 conversion is obtained with a NiO/TiO2 catalyst activated in Ar plasma, when the NiO content is about 10 wt.%. The catalyst characterization data show that Ar plasma treatment results in a higher density of oxygen vacancies and a comparatively more uniform distribution of NiO on the TiO2 surface, which strongly influence CO2 conversion and its energy efficiency. The dissociative electron attachment of CO2 at the catalyst surface enhanced by the oxygen vacancies and by plasma electrons may also explain the increase in conversion and energy efficiencies. A mechanism for the plasma-catalytic CO2 conversion at the surface of an Ar plasma-threated catalyst is proposed.

  15. Experimental research of pulsed discharge plasma and TiO2/Zeolite coupling technology for formaldehyde removal

    Science.gov (United States)

    Dong, Bingyan; Lan, Shuirong

    2013-03-01

    The pulsed discharge plasma combining with catalyst to remove formaldehyde is a novel type of advanced oxidation technology. In the present work, taking wire-tube pulsed discharge plasma and TiO2/Zeolite coupling technology for formaldehyde removal. The studies have investigated the wire-tube reactor with zeolite, TiO2, TiO2/Zeolite for formaldehyde removal respectively. Results show that in the optimal experimental conditions and the baking time is 120 min, the baking temperature is 450 °C, that TiO2/Zeolite catalyst which made by sol-gel shows higher photocatalytic activity and efficiency. The pulsed discharge with TiO2/Zeolite catalyst for formaldehyde removal has higher removal efficiency than pulsed discharge with zeolite or TiO2. Therefore, pulsed discharge plasma with TiO2/Zeolite for the removal of formaldehyde can greatly increase the removal efficiency.

  16. Recent progress in the application of glow-discharge electrolysis plasma

    National Research Council Canada - National Science Library

    Jie Ren; Mengqi Yao; Wu Yang; Yan Li; Jinzhang Gao

    2014-01-01

    ... produced during the glow-discharge electrolysis (GDE) process. A brief review is already available regarding applications of glow-discharge electrolysis plasma technique in chemistry and environmental science during the past decade...

  17. Global Modeling of N2O Discharges: Rate Coefficients and Comparison with ICP and Glow Discharges Results

    Directory of Open Access Journals (Sweden)

    Konstantinos Katsonis

    2013-01-01

    Full Text Available We developed a Global Model for N2O plasmas valid for applications in various power, gas flow rate, and pressure regimes. Besides energy losses from electron collisions with N2O, it takes into consideration those due to molecular N2 and O2 and to atomic N and O species. Positive atomic N+ and O+ and molecular N2O+, N2+, and O2+ have been treated as separate species and also negative O− ions. The latter confer an electronegative character to the discharge, calling for modified plasma sheath and plasma potential formulas. Electron density and temperature and all species densities have been evaluated, hence the ionization and dissociation percentages of N2O, N2, and O2 molecules and the plasma electronegativity. The model is extended to deal with N2/O2 mixtures feedings, notably with air. Rate coefficients and model results are discussed and compared with those from available theoretical and experimental work on ICP and glow discharge devices.

  18. Effects of air transient spark discharge and helium plasma jet on water, bacteria, cells, and biomolecules.

    Science.gov (United States)

    Hensel, Karol; Kučerová, Katarína; Tarabová, Barbora; Janda, Mário; Machala, Zdenko; Sano, Kaori; Mihai, Cosmin Teodor; Ciorpac, Mitică; Gorgan, Lucian Dragos; Jijie, Roxana; Pohoata, Valentin; Topala, Ionut

    2015-06-06

    Atmospheric pressure DC-driven self-pulsing transient spark (TS) discharge operated in air and pulse-driven dielectric barrier discharge plasma jet (PJ) operated in helium in contact with water solutions were used for inducing chemical effects in water solutions, and the treatment of bacteria (Escherichia coli), mammalian cells (Vero line normal cells, HeLa line cancerous cells), deoxyribonucleic acid (dsDNA), and protein (bovine serum albumin). Two different methods of water solution supply were used in the TS: water electrode system and water spray system. The effects of both TS systems and the PJ were compared, as well as a direct exposure of the solution to the discharge with an indirect exposure to the discharge activated gas flow. The chemical analysis of water solutions was performed by using colorimetric methods of UV-VIS absorption spectrophotometry. The bactericidal effects of the discharges on bacteria were evaluated by standard microbiological plate count method. Viability, apoptosis and cell cycle were assessed in normal and cancerous cells. Viability of cells was evaluated by trypan blue exclusion test, apoptosis by Annexin V-FITC/propidium iodide assay, and cell cycle progression by propidium iodide/RNase test. The effect of the discharges on deoxyribonucleic acid and protein were evaluated by fluorescence and UV absorption spectroscopy. The results of bacterial and mammalian cell viability, apoptosis, and cell cycle clearly show that cold plasma can inactivate bacteria and selectively target cancerous cells, which is very important for possible future development of new plasma therapeutic strategies in biomedicine. The authors found that all investigated bio-effects were stronger with the air TS discharge than with the He PJ, even in indirect exposure.

  19. Potential Industrial Applications of the One Atmosphere Uniform Glow Discharge Plasma (OAUGDP) Operating in Ambient Air

    Science.gov (United States)

    Reece Roth, J.

    2004-11-01

    The majority of industrial plasma processing with glow discharges has been conducted at pressures below 10 torr. This tends to limit applications to high value workpieces as a result of the high capital cost of vacuum systems and the production constraints of batch processing. It has long been recognized that glow discharge plasmas would play a much larger industrial role if they could be generated at one atmosphere. The One Atmosphere Uniform Glow Discharge Plasma (OAUGDP), developed at the University of Tennessee's Plasma Sciences Laboratory, is a non-thermal RF plasma operating on displacement currents with the time-resolved characteristics of a classical low pressure DC normal glow discharge. As a glow discharge, the OAUGDP operates with maximum electrical efficiency at the Stoletow point, where the energy input per ion-electron pair is a minimum [1, 2]. Several interdisciplinary teams have investigated potential applications of the OAUGDP. These teams included collaborators from the UTK Textiles and Nonwovens Development Center (TANDEC), and the Departments of Electrical and Computer Engineering, Microbiology, and Food Science and Technology, as well as the NASA Langley Research Center. The potential applications of the OAUGDP have all been at one atmosphere and room temperature, using air as the working gas. These applications include sterilizing medical and dental equipment; sterilizable air filters to deal with the "sick building syndrome"; removal of soot from Diesel engine exhaust; subsonic plasma aerodynamic effects, including flow re-attachment to airfoils and boundary layer modification; electrohydrodynamic (EDH) flow control of working gases; increasing the surface energy of materials; improving the adhesion of paints and electroplated layers: improving the wettability and wickability of fabrics; stripping of photoresist; and plasma deposition and directional etching of potential microelectronic relevance. [1] J. R. Roth, Industrial Plasma Engineering

  20. IR-LAS Measurements of a Pulsed Xenon Discharge Plasma

    Science.gov (United States)

    Jinno, Masafumi; Wada, Ryota; Motomura, Hideki; Aono, Masaharu

    As a first step to understand the processes taking place in a pulsed xenon discharge, the temporal behavior of the radial metastable atom distribution in a xenon lamp was measured by IR laser absorption spectroscopy. During the first 10μs after starting the discharge, high electron density and the depletion of the ground state atoms at the center of the discharge brought about an almost flat distribution of the metastable atoms within the half-radius area. Following that, the metastable atom density became higher at the center than outside because of recombination between electrons and ions. After the metastable density increase and following voltage cut off, the metastable density decreases again. Considering the diffusion equation alongside these results, it becomes clear that the decrease of the metastable density is caused by quenching to the resonace level from the metastable level or three-body collisions forming excimers.

  1. Rice (Oryza sativa L.) Seed Sterilization and Germination Enhancement via Atmospheric Hybrid Nonthermal Discharge Plasma.

    Science.gov (United States)

    Khamsen, Natthaporn; Onwimol, Damrongvudhi; Teerakawanich, Nithiphat; Dechanupaprittha, Sanchai; Kanokbannakorn, Weerawoot; Hongesombut, Komsan; Srisonphan, Siwapon

    2016-08-01

    We designed a system to produce atmospheric hybrid cold-discharge plasma (HCP) based on microcorona discharge on a single dielectric barrier and applied it to inactivate microorganisms that commonly attach the rice seed husk. The cold-plasma treatment modified the surface of the rice seeds, resulting in accelerated germination and enhanced water imbibition. The treatment can operate under air-based ambient conditions without the need for a vacuum. The cold-plasma treatment completely inactivated pathogenic fungi and other microorganisms, enhancing the germination percentage and seedling quality. The final germination percentage of the treated rice seeds was ∼98%, whereas that of the nontreated seeds was ∼90%. Microcorona discharge on a single dielectric barrier provides a nonaggressive cold plasma that can be applied to organic materials without causing thermal and electrical damage. The hybrid nonthermal plasma is cost effective and consumes relatively little power, making it suitable for the surface sterilization and disinfection of organic and biological materials with large-scale compatibility.

  2. Measurements of Rotational Temperatures in Atmospheric-Pressure Capillary Plasma Electrode (CPE) Discharge

    Science.gov (United States)

    Figus, Margaret; Abramzon, Nina; Becker, Kurt

    2003-10-01

    We report the results of rotational temperature measurements in atmospheric-pressure capillary plasma electrode (CPE) discharges in ambient air using the unresolved N2 second positive band. Assuming that the emitting N2 molecules can be described by a Maxwell-Boltzmann distribution characterized by a single rotational temperature, this temperature is determined from a fit of the measured emission spectrum to a calculated spectrum. If the emitting species are in equilibrium with the bulk gas in the plasma, then this temperature can be interpreted as the gas kinetic temperature in the plasma. We determined rotational temperatures for three different plasma regions: inside the capillary by analyzing radiation emitted along the axis of the capillary, between the capillaries, and perpendicular to the axis of the capillary. Each region has a different plasma density and, therefore, a different gas temperature with the plasma inside the capillary being the hottest. We also measured the rotational temperatures in each region as a function of the plasma power. As expected, the rotational temperatures increase with increasing discharge power. Work supported by the NSF and by ARO through a DURIP award.

  3. Dusty plasma microparticle cloud control and rapid electrostatic mutual-repulsion expansion in a DC glow discharge

    Science.gov (United States)

    Gillman, Eric; Amatucci, Bill

    2016-10-01

    Microparticles in plasma discharges rapidly charge up, typically collecting a net negative charge due to the relatively high mobility of electrons compared to ions. Electrostatic forces can be utilized to control charged microparticle behavior and motion in a plasma discharge. In these experiments a metal wire loop is supplied with an electric potential that can be controlled independently from the DC plasma glow discharge electrodes. By varying the voltage on the wire loop, we can attract, trap, manipulate, suspend, and/or repel microparticles that originate from the DC glow discharge. Experiments studied the properties of electrostatic self-repulsion of a cloud of charged microparticles. By pulsing the plasma and controlling wire loop potential, a cloud of trapped microparticles is released and allowed to rapidly expand. A simple force balance simulation code is used as a model to compare and benchmark actual experimental results. This work was supported by the Naval Research Laboratory base program.

  4. Decomposition of L-valine under nonthermal dielectric barrier discharge plasma.

    Science.gov (United States)

    Li, Yingying; Kojtari, Arben; Friedman, Gary; Brooks, Ari D; Fridman, Alex; Ji, Hai-Feng

    2014-02-13

    L-Valine solutions in water and phosphate buffer were treated with nonthermal plasma generated by using a dielectric barrier discharge (DBD) device and the products generated after plasma treatments were characterized by (1)H NMR and GC-MS. Our results demonstrate that L-valine is decomposed to acetone, formic acid, acetic acid, threo-methylaspartic acid, erythro-methlyaspartic acid, and pyruvic acid after direct exposure to DBD plasma. The concentrations of these compounds are time-dependent with plasma treatment. The mechanisms of L-valine under the DBD plasma are also proposed in this study. Acetone, pyruvic acid, and organic radicals (•)CHO, CH3COCH2OO(•) (acetonylperoxy), and CH3COC(OH)2OO(•) (1,1-dihydroxypropan-2-one peroxy) may be the determining chemicals in DNA damage.

  5. Formation and Dynamics of Vortex Structures in Pure and Gas-Discharge Nonneutral Collisionless Electron Plasmas

    CERN Document Server

    Kervalishvili, N A

    2013-01-01

    The comparative analysis of the results of experimental investigations of the processes of formation, interaction and dynamics of vortex structures in pure electron and gas-discharge electron nonneutral plasmas taking place for the period of time much less than the electron-neutral collision time has been given. The general processes of formation and behavior of vortex structures in these two plasmas were considered. The phenomena, taking place only in one of these plasmas were also considered. It is shown that the existing difference in behavior of vortex structures is caused by different initial states of nonneutral electron plasmas. The role of vortex structures in the processes taking place in nonneutral electron plasma is discussed.

  6. Endotoxin removal by radio frequency gas plasma (glow discharge)

    Science.gov (United States)

    Poon, Angela

    2011-12-01

    Contaminants remaining on implantable medical devices, even following sterilization, include dangerous fever-causing residues of the outer lipopolysaccharide-rich membranes of Gram-negative bacteria such as the common gut microorganism E. coli. The conventional method for endotoxin removal is by Food & Drug Administration (FDA)-recommended dry-heat depyrogenation at 250°C for at least 45 minutes, an excessively time-consuming high-temperature technique not suitable for low-melting or heat-distortable biomaterials. This investigation evaluated the mechanism by which E. coli endotoxin contamination can be eliminated from surfaces during ambient temperature single 3-minute to cumulative 15-minute exposures to radio-frequency glow discharge (RFGD)-generated residual room air plasmas activated at 0.1-0.2 torr in a 35MHz electrodeless chamber. The main analytical technique for retained pyrogenic bio-activity was the Kinetic Chromogenic Limulus Amebocyte Lysate (LAL) Assay, sufficiently sensitive to document compliance with FDA-required Endotoxin Unit (EU) titers less than 20 EU per medical device by optical detection of enzymatic color development corresponding to water extracts of each device. The main analytical technique for identification of chemical compositions, amounts, and changes during sequential reference Endotoxin additions and subsequent RFGD-treatment removals from infrared (IR)-transparent germanium (Ge) prisms was Multiple Attenuated Internal Reflection (MAIR) infrared spectroscopy sensitive to even monolayer amounts of retained bio-contaminant. KimaxRTM 60 mm x 15 mm and 50mm x 15mm laboratory glass dishes and germanium internal reflection prisms were inoculated with E. coli bacterial endotoxin water suspensions at increments of 0.005, 0.05, 0.5, and 5 EU, and characterized by MAIR-IR spectroscopy of the dried residues on the Ge prisms and LAL Assay of sterile water extracts from both glass and Ge specimens. The Ge prism MAIR-IR measurements were

  7. Simulation of Dual-Electrode Capacitively Coupled Plasma Discharges

    Science.gov (United States)

    Lu, Yijia; Ji, Linhong; Cheng, Jia

    2016-12-01

    Dual-electrode capacitively coupled plasma discharges are investigated here to lower the non-uniformity of plasma density. The dual-electrode structure proposed by Jung splits the electrode region and increases the flexibility of fine tuning non-uniformity. Different RF voltages, frequencies, phase-shifts and electrode areas are simulated and the influences are discussed. RF voltage and electrode area have a non-monotonic effect on non-uniformity, while frequency has a monotonic effect. Phase-shift has a cyclical influence on non-uniformity. A special combination of 224 V voltage and 11% area ratio with 10 MHz lowers the non-uniformity of the original set (200 V voltage and 0% area ratio with 10 MHz) by 46.5%. The position of the plasma density peak at the probe line has been tracked and properly tuning the phase-shift can obtain the same trace as tuning frequency or voltage. supported by National Natural Science Foundation of China (No. 51405261)

  8. MERCURY OXIDIZATION IN NON-THERMAL PLASMA BARRIER DISCHARGE SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    V.K. Mathur

    2003-02-01

    In the past decade, the emission of toxic elements from human activities has become a matter of great public concern. Hg, As, Se and Cd typically volatilize during a combustion process and are not easily caught with conventional air pollution control techniques. In addition, there is no pollution prevention technique available now or likely be available in the foreseeable future that can prevent the emission of these trace elements. These trace elements pose additional scientific challenge as they are present at only ppb levels in large gas streams. Mercury, in particular, has attracted significant attention due to its high volatility, toxicity and potential threat to human health. In the present research work, a non-thermal plasma dielectric barrier discharge technique has been used to oxidize Hg{sup 0}(g) to HgO. The basic premise of this approach is that Hg{sup 0} in vapor form cannot be easily removed in an absorption tower whereas HgO as a particulate is amiable to water scrubbing. The work presented in this report consists of three steps: (1) setting-up of an experimental apparatus to generate mercury vapors at a constant rate and modifying the existing non-thermal plasma reactor system, (2) solving the analytical challenge for measuring mercury vapor concentration at ppb level, and (3) conducting experiments on mercury oxidation under plasma conditions to establish proof of concept.

  9. Modification of Composite Material Fillers by Atmospheric Plasma Discharge

    Directory of Open Access Journals (Sweden)

    David Tichy

    2013-01-01

    Full Text Available This work is focused on the observation of the influence of cold atmospheric dielectric barrier discharge (DBD on a modification of textile samples. The main objective of the experiment is to research wettability change of textiles modified by different exposure times and also the observation of the influence of a modification ageing effect. An ambient air was used as a working gas for DBD plasma. The wettability evaluation was carried out by a drop method, in which an imprint of the dropwas observed on the textile surface during various time intervals. An ageing effect of the modification was monitored within an interval of 28 days. Considerable increase of wettability of all modified samples has been proved. A fibre surface analysis was carried out by means of SEM.

  10. Pattern phenomena in an rf discharge dusty plasma system

    Institute of Scientific and Technical Information of China (English)

    HUANG Feng; YE Maofu; WANG Long

    2006-01-01

    Various dust patterns are observed in an rf discharge dusty plasma system.According to the dust growth process from small to large in size, the formation of different dust patterns can be divided into two stages: the small-particle stage (or dust cloud stage),and the large-particle stage (or dust crystal stage). The evolution relations between different dust patterns with gas pressure changing are investigated. Dust voids, dust acoustic waves and strong turbulence modes are presented at the small-particle stage. The self-organized dust lattices and dust clusters are investigated at the large-particle stage.The static structure of a dust lattice is characterized by means of the pair correlation function. Dust clusters formed by particles with different numbers and the regular evolution of the clusters with gas pressure are also investigated. The packing sequences of dust clusters are verified through two-dimensional confined molecular dynamics simulations.

  11. Fast plasma discharge capillary design as a high power throughput soft x-ray emission source.

    Science.gov (United States)

    Wyndham, E S; Favre, M; Valdivia, M P; Valenzuela, J C; Chuaqui, H; Bhuyan, H

    2010-09-01

    We present the experimental details and results from a low energy but high repetition rate compact plasma capillary source for extreme ultraviolet and soft x-ray research and applications. Two lengths of capillary are mounted in two versions of a closely related design. The discharge operates in 1.6 and 3.2 mm inner diameter alumina capillaries of lengths 21 and 36 mm. The use of water both as dielectric and as coolant simplifies the compact low inductance design with nanosecond discharge periods. The stored electrical energy of the discharge is approximately 0.5 J and is provided by directly charging the capacitor plates from an inexpensive insulated-gate bipolar transistor in 1 μs or less. We present characteristic argon spectra from plasma between 30 and 300 Å as well as temporally resolved x-ray energy fluence in discrete bands on axis. The spectra also allow the level of ablated wall material to be gauged and associated with useful capillary lifetime according to the chosen configuration and energy storage. The connection between the electron beams associated with the transient hollow cathode mechanism, soft x-ray output, capillary geometry, and capillary lifetime is reported. The role of these e-beams and the plasma as measured on-axis is discussed. The relation of the electron temperature and the ionization stages observed is discussed in the context of some model results of ionization in a non-Maxwellian plasma.

  12. Large Scale Modelling of Glow Discharges or Non - Plasmas

    Science.gov (United States)

    Shankar, Sadasivan

    The Electron Velocity Distribution Function (EVDF) in the cathode fall of a DC helium glow discharge was evaluated from a numerical solution of the Boltzmann Transport Equation(BTE). The numerical technique was based on a Petrov-Galerkin technique and a unique combination of streamline upwinding with self -consistent feedback-based shock-capturing. EVDF for the cathode fall was solved at 1 Torr, as a function of position x, axial velocity v_{rm x}, radial velocity v_{rm r}, and time t. The electron-neutral collisions consisted of elastic, excitation, and ionization processes. The algorithm was optimized and vectorized to speed execution by more than a factor of 10 on CRAY-XMP. Efficient storage schemes were used to save the memory allocation required by the algorithm. The analysis of the solution of BTE was done in terms of the 8-moments that were evaluated. Higher moments were found necessary to study the momentum and energy fluxes. The time and length scales were estimated and used as a basis for the characterization of DC glow discharges. Based on an exhaustive study of Knudsen numbers, it was observed that the electrons in the cathode fall were in the transition or Boltzmann regime. The shortest relaxation time was the momentum relaxation and the longest times were the ionization and energy relaxation times. The other times in the processes were that for plasma reaction, diffusion, convection, transit, entropy relaxation, and that for mean free flight between the collisions. Different models were classified based on the moments, time scales, and length scales in their applicability to glow discharges. These consisted of BTE with different number af phase and configuration dimensions, Bhatnagar-Gross-Krook equation, moment equations (e.g. Drift-Diffusion, Drift-Diffusion-Inertia), and spherical harmonic expansions.

  13. Study on the Generation Characteristics of Dielectric Barrier Discharge Plasmas on Water Surface

    Science.gov (United States)

    Liu, Wenzheng; Li, Chuanhui

    2014-01-01

    A new contact glow discharge electrode on the surface of water was designed and employed in this study. Because of the strong field strength in the small air gap formed by the electrode and the water surface, glow discharge plasmas were generated and used to treat waste water. The electric field distribution of the designed electrode model was simulated by MAXWELL 3D® simulation software, and the discharge parameters were measured. Through a series of experiments, we investigated the impact of optimal designs, such as the dielectric of the electrode, immersion depths, and curvature radii of the electrode on the generation characteristics of plasmas. In addition, we designed an equipotential multi-electrode configuration to treat a Methyl Violet solution and observe the discoloration effect. The experimental and simulation results indicate that the designed electrodes can realize glow discharge with a relative low voltage, and the generated plasmas covered a large area and were in stable state. The efficiency of water treatment is improved and optimized with the designed electrodes.

  14. Conversion of methane through dielectric-barrier discharge plasma

    Institute of Scientific and Technical Information of China (English)

    Baowei WANG; Xiaolei CAO; Kuanhui YANG; Genhui XU

    2008-01-01

    Methane coupling to produce C2 hydrocar-bons through a dielectric-barrier discharge (DBD) plasma reaction was studied in four DBD reactors. The effects of high voltage electrode position, different discharge gap, types of inner electrode, volume ratio of hydrogen to methane and air cooling method on the conversion of methane and distribution of products were investigated. Conversion of methane is obviously lower when a high voltage electrode acts as an outer electrode than when it acts as an inner electrode. The lifting of reaction temper-ature becomes slow due to cooling of outer electrode and the temperature can be controlled in the expected range of 60℃-150℃ for ensuring better methane conversion and safe operation. The parameters of reactors have obvious effects on methane conversion, but it only slightly affects distribution of the products. The main products are ethyl-ene, ethane and propane. The selectivity of C2 hydrocar-bons can reach 74.50% when volume ratio of hydrogen to methane is 1.50.

  15. The α and γ plasma modes in plasma-enhanced atomic layer deposition with O2–N2 capacitive discharges

    Science.gov (United States)

    Napari, M.; Tarvainen, O.; Kinnunen, S.; Arstila, K.; Julin, J.; Fjellvåg, Ø. S.; Weibye, K.; Nilsen, O.; Sajavaara, T.

    2017-03-01

    Two distinguishable plasma modes in the O2–N2 radio frequency capacitively coupled plasma (CCP) used in remote plasma-enhanced atomic layer deposition (PEALD) were observed. Optical emission spectroscopy and spectra interpretation with rate coefficient analysis of the relevant processes were used to connect the detected modes to the α and γ modes of the CCP discharge. To investigate the effect of the plasma modes on the PEALD film growth, ZnO and TiO2 films were deposited using both modes and compared to the films deposited using direct plasma. The growth rate, thickness uniformity, elemental composition, and crystallinity of the films were found to correlate with the deposition mode. In remote CCP operations the transition to the γ mode can result in a parasitic discharge leading to uncontrollable film growth and thus limit the operation parameters of the capacitive discharge in the PEALD applications.

  16. Rapid Formation of Distributed Plasma Discharges using X-Band Microwaves

    Science.gov (United States)

    Xiang, Xun

    Observations of rapidly formed (plasma discharges using high power X-band microwaves are presented. A cylindrical stainless steel chamber (15.2 cm long, 14.6 cm diameter) enclosed with polycarbonate windows (0.953 cm) was used to observe microwave breakdown in argon and neon gas mixtures from 50 to 250 torr. The chamber was illuminated by the output of a 16.2 kW, 800 ns pulse-width, 9.382 GHz magnetron with a 43 repetitive rate through an X-band waveguide pressed against the first polycarbonate window. Fast (50 ns) time-scale optical images of the plasma revealed the plasma formation and decay processes, as well as the plasma patterns for different plasma formation conditions. CST simulations were conducted to compare the electric field distribution inside the discharge chamber with the plasma patterns in the images. VUV (Vacuum Ultra-Violet) radiation was supported as the mechanism to enhance the plasma expansion and assist the formation of the plasma side lobes. Reflection Measurements showed 63% reflected power once plasma was formed, and a small amount of argon in neon shortened the breakdown time, verifying that the Penning effect lowers the breakdown threshold. Mixer measurements were taken, combined with a 1-D 6-region microwave plasma model to estimate the maximum effective plasma density as 2.2x1012 cm-3 with a corresponding maximum effective electron temperature of 2.5 eV in pure neon plasma at 100 torr under a Maxwellian distribution assumption. Optical emission spectroscopy (OES) assisted by the SPECAIR model determined the gas temperature in the microwave plasma as 350 +/- 50 K. OES line ratio measurements provided plasma parameters including time-evolved metastable and resonance densities, effective electron temperatures, electron densities for plasmas formed at 100 torr in pure neon and Ne/Ar (99:1) mixture gases. The comparison of time-evolved neon metastable and resonance densities in pure neon and Ne/Ar (99:1) mixture plasmas verified the Penning

  17. Polarity functions' characterization and the mechanism of starch modification by DC glow discharge plasma.

    Science.gov (United States)

    Khorram, S; Zakerhamidi, M S; Karimzadeh, Z

    2015-01-01

    The wheat starch was investigated, before and after exposure to the argon and oxygen glow discharge plasma, without any added chemical reagents, using a novel media polarity functions method. The mechanisms of modification of starch in plasma discharge irradiation were explained using some methods such as; NMR, IR spectroscopy, Kamlet-Abboud-Taft polarity functions (specific and nonspecific interaction) of modified starch. The starch modification, by plasma treatment, shows valuable changes with plasma gas and relative ionized or active species. Characterizations indicate that argon glow discharge plasma increases crosslink in C-2 site of starch. Also, oxygen plasma discharge irradiation tends to oxidize the OH group in C-6 site of carbonyl group. Furthermore, the reported mechanisms show the highest efficiency, because of the stereo-chemical orientation of active sites of starch and plasma potential of wall in plasma media. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Scaling and laws of DC discharges as pointers for HiPIMS plasmas

    CERN Document Server

    Maszl, Christian; von Keudell, Achim; Störi, Herbert

    2015-01-01

    Scaling or smiliarity laws of plasmas are of interest if lab size plasma sources are to be scaled for industrial processes. Ideally, the discharge parameters of the scaled plasmas are predictable and the fundamental physical processes are unaltered. Naturally, there are limitations and ranges of validity. Scaling laws for direct current glow discharges are well known. If a well diagnosed discharge is scaled, the field strength in the positive column, the gas amplification and the normal current density can easily be estimated. For non-stationary high power discharges like high power impulse magnetron sputtering (HiPIMS) plasmas, scaling is not as straight forward. Here, one deals with a non-stationary complex system with strong changes in plasma chemistry and symmetry breaks during the pulses. Because of the huge parameter space no good parameters are available to define these kind of discharges unambiguous at the moment. In this contribution we will discuss the scaling laws for DC glow discharges briefly and...

  19. Modeling of Plasma-Assisted Conversion of Liquid Ethanol into Hydrogen Enriched Syngas in the Nonequilibrium Electric Discharge Plasma-Liquid System

    CERN Document Server

    Levko, Dmitry; Naumov, Vadim; Chernyak, Valery; Yukhymenko, Vitaly; Prysiazhnevych, Irina; Olszewski, Sergey

    2008-01-01

    In this work we report recent results of our experimental and theoretical studies related to plasma conversion of liquid ethanol into hydrogen-enriched syngas in the plasma-liquid system with the electric discharge in a gas channel with liquid wall using available diagnostics and numerical modeling.

  20. Plasmas in Multiphase Media: Bubble Enhanced Discharges in Liquids and Plasma/Liquid Phase Boundaries

    Energy Technology Data Exchange (ETDEWEB)

    Kushner, Mark Jay [University of Michigan

    2014-07-10

    In this research project, the interaction of atmospheric pressure plasmas with multi-phase media was computationally investigated. Multi-phase media includes liquids, particles, complex materials and porous surfaces. Although this investigation addressed fundamental plasma transport and chemical processes, the outcomes directly and beneficially affected applications including biotechnology, medicine and environmental remediation (e.g., water purification). During this project, we made advances in our understanding of the interaction of atmospheric pressure plasmas in the form of dielectric barrier discharges and plasma jets with organic materials and liquids. We also made advances in our ability to use computer modeling to represent these complex processes. We determined the method that atmospheric pressure plasmas flow along solid and liquid surfaces, and through endoscopic like tubes, deliver optical and high energy ion activation energy to organic and liquid surfaces, and produce reactivity in thin liquid layers, as might cover a wound. We determined the mechanisms whereby plasmas can deliver activation energy to the inside of liquids by sustaining plasmas in bubbles. These findings are important to the advancement of new technology areas such as plasma medicine

  1. Canard-induced mixed mode oscillations in an excitable glow discharge plasmas

    CERN Document Server

    Nurujjaman, M

    2014-01-01

    We demonstrated experimentally canard induced mixed mode oscillations (MMO) in an excitable glow discharge plasma, and the results are validated through numerical solution of the FitzHugh Nagumo (FHN) model. When glow discharge plasma is perturbed by applying a magnetic field, it shows mixed mode oscillatory activity, i.e., quasiperiodic small oscillations interposed with large bounded limit cycles oscillations. The initial quasiperiodic oscillations were observed to change into large amplitude limit cycle oscillations with magnetic field, and the number of these oscillation increases with increase in the magnetic field. Fourier analysis of both numerical and experimental results show that the origin of these oscillations are canard-induced phenomena, which occurs near the threshold of the control parameter. Further, the phase space plots also confirm that the oscillations are basically canard-induced MMOs.

  2. Correlation between discharging property and coatings microstructure during plasma electrolytic oxidation

    Institute of Scientific and Technical Information of China (English)

    GUAN Yong-jun; XIA Yuan

    2006-01-01

    The voltage-current properties during plasma electrolytic discharge were determined by measuring the current density and cell voltage as functions of processing time and then by mathematical transformation. Correlation between discharge I-V property and the coatings microstructure on aluminum alloy during plasma electrolytic oxidation was determined by comparing the voltage-current properties at different process stages with SEM results of the corresponding coatings. The results show that the uniform passive film corresponds to a I-V property with one critical voltage, and a compound of porous layer and sintered ceramic particles corresponds to a I-V property with two critical voltages. The growth regularity of PEO cermet coatings was also studied.

  3. Synthesis of magnetic nanoparticles by atmospheric-pressure glow discharge plasma-assisted electrolysis

    Science.gov (United States)

    Shirai, Naoki; Yoshida, Taketo; Uchida, Satoshi; Tochikubo, Fumiyoshi

    2017-07-01

    For the synthesis of magnetic nanoparticles (NPs), we used plasma-assisted electrolysis in which atmospheric-pressure DC glow discharge using a liquid electrode is combined with electrolysis. The solution surface is exposed to positive ions or electrons in plasma. To synthesize magnetic NPs, aqueous solutions of FeCl2 or an iron electrode immersed in liquid was used to supply iron ions in the liquid. Magnetic NPs were synthesized at the plasma-liquid interface upon the electron irradiation of the liquid surface. In the case of using aqueous solutions of FeCl2, the condition of magnetic NP synthesis depended on the gas species of plasma and the chemical agent in the liquid for controlling oxidization. The amount of magnetic NPs synthesized using plasma is not very large. On the other hand, in the case of using an iron electrode immersed in NaCl solution, magnetic NPs were synthesized without using FeCl2 solutions. When plasma-assisted electrolysis was operated, the iron electrode eluted Fe cations, resulting in the formation of magnetic NPs at the plasma-liquid interface. Magnetic NP synthesis depended on the concentration of NaCl solution and discharge current. The magnetic NPs were identified to be magnetite. By using this method, more magnetite NPs were synthesized than in the case of plasma-assisted electrolysis with FeCl2 aqueous solutions. The pH of the liquid used in plasma-assisted electrolysis was important for the synthesis of magnetite NPs.

  4. Physical and plasmachemical aspects of diffuse coplanar barrier discharge as a novel atmospheric-pressure plasma source

    Science.gov (United States)

    Cernak, M.; Kovacik, D.; Zahoranova, A.; Rahel, J.

    2008-07-01

    Collaborating Czech and Slovakian university teams have recently developed an innovative plasma source, the so-called Diffuse Coplanar Surface Barrier Discharge (DCSBD), which has the potential to move a step closer to the industry requirement for in-line treatment of low-added-value materials using a highly-nonequlibrium ambient air plasma (Simor et al. 2002, The idea is to generate a thin (on the order of 0.1 mm) layer of highly-nonequlibrium plasma with a high power density (up to 100 W/cm^3) in the immediate vicinity of the treated surface and bring it into a close contact with the treated surface. Comparing to atmospheric-pressure glow discharge, volume dielectric barrier discharge, and plasma jet plasmas, such a diffuse plasma layer is believed to provide substantial advantages in energy consumption, exposure time, and technical simplicity. A brief outline of physical mechanism and basic properties of DCSBD will given using the results of emission spectroscopy, high-speed camera, and spatially resolved cross-correlation spectroscopy studies. The presentation will review also a current state of the art in in-line plasma treatment of low-cost materials and opportunities for the use of the so-called Diffuse Coplanar Surface Dielectric Barrier Discharge (DCSBD). The results obtained on the ambient air plasma treatments of textile, paper, wood, and glass illustrate that DCSBD offers outstanding performance with extremely low energy consumption for large area, uniform surface modifications of materials under continuous process conditions.

  5. Cold atmospheric plasma discharged in water and its potential use in cancer therapy

    Science.gov (United States)

    Chen, Zhitong; Cheng, Xiaoqian; Lin, Li; Keidar, Michael

    2017-01-01

    Cold atmospheric plasma (CAP) has emerged as a novel technology for cancer treatment. CAP can directly treat cells and tissue but such direct application is limited to skin or can be invoked as a supplement during open surgery. In this study we report indirect plasma treatment using CAP discharged in deionized (DI) water using three gases as carriers (argon (Ar), helium (He), and nitrogen (N2)). Plasma stimulated water was applied to the human breast cancer cell line (MDA-MB-231). MTT (3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay tests showed that using Ar plasma had the strongest effect on inducing apoptosis in cultured human breast cancer cells. This result is attributed to the elevated production of reactive oxygen species and reactive nitrogen species in water.

  6. Improved performance of a barrier-discharge plasma jet biased by a direct-current voltage

    Science.gov (United States)

    Li, Xuechen; Li, Yaru; Zhang, Panpan; Jia, Pengying; Dong, Lifang

    2016-01-01

    One of the challenges that plasma research encounters is how to generate a large-scale plasma plume at atmospheric pressure. Through utilizing a third electrode biased by a direct-current voltage, a longer plasma plume is generated by a plasma jet in dielectric barrier discharge configurations. Results indicate that the plume length increases until it reaches the third electrode with increasing the bias voltage. By fast photography, it is found that the plume consists of two types of streamers under the influence of the bias voltage, which develops from a guided streamer to a branching one with leaving the tube opening. The transition from the guided streamer to the branching one can be attributed to the electric field and the air/argon fraction. PMID:27759080

  7. Improved performance of a barrier-discharge plasma jet biased by a direct-current voltage

    Science.gov (United States)

    Li, Xuechen; Li, Yaru; Zhang, Panpan; Jia, Pengying; Dong, Lifang

    2016-10-01

    One of the challenges that plasma research encounters is how to generate a large-scale plasma plume at atmospheric pressure. Through utilizing a third electrode biased by a direct-current voltage, a longer plasma plume is generated by a plasma jet in dielectric barrier discharge configurations. Results indicate that the plume length increases until it reaches the third electrode with increasing the bias voltage. By fast photography, it is found that the plume consists of two types of streamers under the influence of the bias voltage, which develops from a guided streamer to a branching one with leaving the tube opening. The transition from the guided streamer to the branching one can be attributed to the electric field and the air/argon fraction.

  8. Comparative study of NO removal in surface-plasma and volume-plasma reactors based on pulsed corona discharges.

    Science.gov (United States)

    Malik, Muhammad Arif; Kolb, Juergen F; Sun, Yaohong; Schoenbach, Karl H

    2011-12-15

    Nitric oxide (NO) conversion has been studied for two different types of atmospheric-pressure pulsed-corona discharges, one generates a surface-plasma and the other provides a volume-plasma. For both types of discharges the energy cost for NO removal increases with decreasing oxygen concentration and initial concentration of NO. However, the energy cost for volume plasmas for 50% NO removal, EC(50), from air was found to be 120 eV/molecule, whereas for the surface plasma, it was only 70 eV/molecule. A smaller difference in energy cost, but a higher efficiency for removal of NO was obtained in a pure nitrogen atmosphere, where NO formation is restricted due to the lack of oxygen. For the volume plasma, EC(50) in this case was measured at 50 eV/molecule, and for the surface plasma it was 40 eV/molecule. Besides the higher NO removal efficiency of surface plasmas compared to volume plasmas, the energy efficiency of surface-plasmas was found to be almost independent of the amount of electrical energy deposited in the discharge, whereas the efficiency for volume plasmas decreases considerably with increasing energy. This indicates the possibility of operating surface plasma discharges at high energy densities and in more compact reactors than conventional volume discharges.

  9. Comparative study of NO removal in surface-plasma and volume-plasma reactors based on pulsed corona discharges

    Energy Technology Data Exchange (ETDEWEB)

    Malik, Muhammad Arif, E-mail: MArifMalik@gmail.com [Frank Reidy Research Center for Bioelectrics, Old Dominion University, 4211 Monarch Way, Suite 300, Norfolk, VA 23508 (United States); Kolb, Juergen F.; Sun, Yaohong; Schoenbach, Karl H. [Frank Reidy Research Center for Bioelectrics, Old Dominion University, 4211 Monarch Way, Suite 300, Norfolk, VA 23508 (United States)

    2011-12-15

    Nitric oxide (NO) conversion has been studied for two different types of atmospheric-pressure pulsed-corona discharges, one generates a surface-plasma and the other provides a volume-plasma. For both types of discharges the energy cost for NO removal increases with decreasing oxygen concentration and initial concentration of NO. However, the energy cost for volume plasmas for 50% NO removal, EC{sub 50}, from air was found to be 120 eV/molecule, whereas for the surface plasma, it was only 70 eV/molecule. A smaller difference in energy cost, but a higher efficiency for removal of NO was obtained in a pure nitrogen atmosphere, where NO formation is restricted due to the lack of oxygen. For the volume plasma, EC{sub 50} in this case was measured at 50 eV/molecule, and for the surface plasma it was 40 eV/molecule. Besides the higher NO removal efficiency of surface plasmas compared to volume plasmas, the energy efficiency of surface-plasmas was found to be almost independent of the amount of electrical energy deposited in the discharge, whereas the efficiency for volume plasmas decreases considerably with increasing energy. This indicates the possibility of operating surface plasma discharges at high energy densities and in more compact reactors than conventional volume discharges.

  10. Miniature Dielectric Barrier Discharge Nonthermal Plasma Induces Apoptosis in Lung Cancer Cells and Inhibits Cell Migration

    Science.gov (United States)

    Eisenmann, Kathryn M.

    2017-01-01

    Traditional cancer treatments like radiotherapy and chemotherapy have drawbacks and are not selective for killing only cancer cells. Nonthermal atmospheric pressure plasmas with dielectric barrier discharge (DBD) can be applied to living cells and tissues and have emerged as novel tools for localized cancer therapy. The purpose of this study was to investigate the different effects caused by miniature DBD (mDBD) plasma to A549 lung cancer cells. In this study, A549 lung cancer cells cultured in 12 well plates were treated with mDBD plasma for specified treatment times to assess the changes in the size of the area of cell detachment, the viability of attached or detached cells, and cell migration. Furthermore, we investigated an innovative mDBD plasma-based therapy for localized treatment of lung cancer cells through apoptotic induction. Our results indicate that plasma treatment for 120 sec causes apoptotic cell death in 35.8% of cells, while mDBD plasma treatment for 60 sec, 30 sec, or 15 sec causes apoptotic cell death in 20.5%, 14.1%, and 6.3% of the cell population, respectively. Additionally, we observed reduced A549 cell migration in response to mDBD plasma treatment. Thus, mDBD plasma system can be a viable platform for localized lung cancer therapy. PMID:28243603

  11. Reel-to-Reel Atmospheric Pressure Dielectric Barrier Discharge (DBD Plasma Treatment of Polypropylene Films

    Directory of Open Access Journals (Sweden)

    Lukas JW Seidelmann

    2017-03-01

    Full Text Available Atmospheric pressure plasma treatment of the surface of a polypropylene film can significantly increase its surface energy and, thereby improve the printability of the film. A laboratory-scale dielectric barrier discharge (DBD system has therefore been developed, which simulates the electrode configuration and reel-to-reel web transport mechanism used in a typical industrial-scale system. By treating the polypropylene in a nitrogen discharge, we have shown that the water contact angle could be reduced by as much as 40° compared to the untreated film, corresponding to an increase in surface energy of 14 mNm−1. Ink pull-off tests showed that the DBD plasma treatment resulted in excellent adhesion of solvent-based inks to the polypropylene film.

  12. Methane Incorporation into Liquid Fuel by Non-Equilibrium Plasma Discharges

    CERN Document Server

    Liu, Chong; Ji, Hai-Feng; Smith, Joshua; Rabinovich, Alexander; Dobrynin, Danil; Fridman, Alexander

    2016-01-01

    The conventional ways of processing natural gas into more efficient and economical fuels usually either have low conversion rate or low energy efficiency. In this work, a new approach of methane liquefaction is proposed. Instead of direct treatment of only natural gas, plasma activated methane is reacting with liquid fuel. In this way, methane molecules are directly incorporated onto liquid fuel to achieve liquefaction. Nanosecond-pulsed dielectric barrier discharge and atmospheric pressure glow discharge are used here to ensure no local heating in gas bubbles. Effects of both discharges on methane reaction with liquid fuel are investigated, mass and chemical changes in liquid are observed. Preliminary results show fixation of methane in liquid fuel.

  13. The role of gas composition in plasma-dust structures in RF discharge

    Energy Technology Data Exchange (ETDEWEB)

    Maiorov, S. A., E-mail: maiorov-sa@mail.ru [Prokhorov General Physics Institute, Russian Academy of Sciences, Vavilov st. 38, Moscow 119991 (Russian Federation); Joint Institute for High Temperatures, Russian Academy of Sciences, Izhorskaya st. 13/19, Moscow 127412 (Russian Federation); Kodanova, S. K.; Dosbolayev, M. K.; Ramazanov, T. S.; Bastykova, N. Kh.; Utegenov, A. U. [Institute of Experimental and Theoretical Physics, Al-Farabi Kazakh National University, Al-Farabi 71, Almaty 050040 (Kazakhstan); Golyatina, R. I. [Prokhorov General Physics Institute, Russian Academy of Sciences, Vavilov st. 38, Moscow 119991 (Russian Federation)

    2015-03-15

    The influence of a mixture of light and heavy gases, i.e., helium and argon, on plasma-dust structures in the radiofrequency discharge has been studied. The dust chains in the sheath of the radiofrequency discharge, the average distance between the dust particles and their chains, have been analyzed. A significant effect of small amounts of argon on the correlation characteristics of dust particles has been observed. The results of numerical simulation of ion and electron drift in the mixture of helium and argon are presented. It is shown that even 1% of argon admixture to helium produces such an effect that argon ions become the main components of the discharge, as they drift with lightweight helium forming a strongly anisotropic velocity distribution function.

  14. Effect of discharge polarity on the propagation of atmospheric-pressure helium plasma jets and the densities of OH, NO, and O radicals.

    Science.gov (United States)

    Yonemori, Seiya; Ono, Ryo

    2015-06-01

    The atmospheric-pressure helium plasma jet is an emerging technology for plasma biomedical applications. In this paper, the authors focus on the effect of discharge polarity on propagation of the discharge and the densities of OH, NO, and O radicals. The plasma jet is applied to a glass surface placed on a grounded metal plate. Positive or negative voltage pulses with 25 μs duration, 8 kV amplitude, and 10 kpps repetition rate are used for the plasma jet. The plasma propagation is measured using a short-gated ICCD camera. The light emission intensity of the discharge generated at the rising phase of the voltage pulse is approximately equivalent for both polarities, while that generated during the falling phase is much higher for the negative discharge than the positive one. The shape of the discharge changes with the discharge polarity. The OH, NO, and O densities in the plasma jet are also measured for both polarities. It is found that the OH density is almost the same regardless the discharge polarity. Conversely, the negative discharge produces more O atoms and the positive discharge produces more NO molecules. These results indicate that the polarity of the discharge affects the densities of some reactive species produced in the plasma jet.

  15. Boltzmann statistical consideration on the excitation mechanism of iron atomic lines emitted from glow discharge plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Lei; Kashiwakura, Shunsuke; Wagatsuma, Kazuaki, E-mail: wagatuma@imr.tohoku.ac.jp

    2011-11-15

    A Boltzmann plot for many iron atomic lines having excitation energies of 3.3-6.9 eV was investigated in glow discharge plasmas when argon or neon was employed as the plasma gas. The plot did not show a linear relationship over a wide range of the excitation energy, but showed that the emission lines having higher excitation energies largely deviated from a normal Boltzmann distribution whereas those having low excitation energies (3.3-4.3 eV) well followed it. This result would be derived from an overpopulation among the corresponding energy levels. A probable reason for this is that excitations for the high-lying excited levels would be caused predominantly through a Penning-type collision with the metastable atom of argon or neon, followed by recombination with an electron and then stepwise de-excitations which can populate the excited energy levels just below the ionization limit of iron atom. The non-thermal excitation occurred more actively in the argon plasma rather than the neon plasma, because of a difference in the number density between the argon and the neon metastables. The Boltzmann plots yields important information on the reason why lots of Fe I lines assigned to high-lying excited levels can be emitted from glow discharge plasmas. - Highlights: Black-Right-Pointing-Pointer This paper shows the excitation mechanism of Fe I lines from a glow discharge plasma. Black-Right-Pointing-Pointer A Boltzmann distribution is studied among iron lines of various excitation levels. Black-Right-Pointing-Pointer We find an overpopulation of the high-lying energy levels from the normal distribution. Black-Right-Pointing-Pointer It is caused through Penning-type collision of iron atom with argon metastable atom.

  16. Treatment of Wastewater with High Conductivity by Pulsed Discharge Plasma

    Science.gov (United States)

    Wang, Zhaojun; Jiang, Song; Liu, Kefu

    2014-07-01

    A wastewater treatment system was established by means of pulsed dielectric barrier discharge (DBD). The main advantage of this system is that the wastewater is employed as one of the electrodes for the degradation of rhodamine B, which makes use of the high conductivity and lessenes its negative influence on the discharge process. At the same time, the reactive species like ozone and ultraviolet (UV) light generated by the DBD can be utilized for the treatment of wastewater. The effects of some factors like conductivity, peak pulse voltage, discharge frequency and pH values were investigated. The results show that the combination of these reactive species could enhance the degradation of the dye while the ozone played the most important role in the process. The degradation efficiency was enhanced with the increase of energy supplied. The reduction in the concentration of rhodamine B was much more effective with high solution conductivity; under the highest conductivity condition, the degradation rate could rise to 99%.

  17. Numerical study on the characteristics of nitrogen discharge at high pressure with induced plasma

    Institute of Scientific and Technical Information of China (English)

    Wang Yi-Nan; Liu Yue; Zheng Shu; Lin Guo-Qiang

    2012-01-01

    Based on the fluid theory of plasma,a model is built to study the characteristics of nitrogen discharge at high pressure with induced argon plasma.In the model,species such as electrons,N2+,N4+,Ar+,and two metastable states (N2(A3 ∑ u+),N2(a1 ∑ u-)) are taken into account.The model includes the particle continuity equation,the electron energy balance equation,and Poisson(柤)equation.The model is solved with a finite difference method.The numerical results are obtained and used to investigate the effect of time taken to add nitrogen gas and initially-induced argon plasma pressure.It is found that lower speeds of adding the nitrogen gas and varying the gas pressure can induce higher plasma density,and inversely lower electron temperature.At high-pressure discharge,the electron density increases when the proportion of nitrogen component is below 40%,while the electron density will keep constant as the nitrogen component further increases.It is also shown that with the increase of initially-induced argon plasma pressure,the density of charged particles increases,and the electron temperature as well as the electric field decreases.

  18. Plasma decay in high-voltage nanosecond discharges in oxygen-containing mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Anokhin, E. M.; Popov, M. A. [Moscow Institute of Physics and Technology (Russian Federation); Kochetov, I. V. [Troitsk Institute for Innovation and Fusion Research (Russian Federation); Aleksandrov, N. L., E-mail: nick-aleksandrov@mail.ru [Moscow Institute of Physics and Technology (Russian Federation); Starikovskii, A. Yu. [Princeton University (United States)

    2016-01-15

    Plasma decay in high-voltage nanosecond discharges in CO{sub 2}: O{sub 2} and Ar: O{sub 2} mixtures at room gas temperature and a pressure of 10 Torr is studied experimentally and theoretically. The time dependence of the electron density during plasma decay is measured using microwave interferometry. The time evolution of the charged particle density, ion composition, and electron temperature is simulated numerically. It is shown that, under the given conditions, the discharge plasma is dominated for the most time by O{sub 2}{sup +} ions and plasma decay is determined by dissociative and three-body electron−ion recombination. As in the previous studies performed for air and oxygen plasmas, agreement between measurements and calculations is achieved only under the assumption that the rate of three-body recombination of molecular ions is much greater than that for atomic ions. The values of the rate constant of three-body recombination of electrons with O{sub 2}{sup +} ions in a wide range of electron temperatures (500–5500 K), as well as for thermal (300 K) electrons, are obtained by processing the experimental results.

  19. Surface modification of chitosan/PEO nanofibers by air dielectric barrier discharge plasma for acetylcholinesterase immobilization

    Energy Technology Data Exchange (ETDEWEB)

    Dorraki, Naghme, E-mail: n.dorraki@web.sbu.ac.ir [Laser and Plasma Research Institute, Shahid Beheshti University, Evin 1983963113, Tehran (Iran, Islamic Republic of); Safa, Nasrin Navab [Laser and Plasma Research Institute, Shahid Beheshti University, Evin 1983963113, Tehran (Iran, Islamic Republic of); Jahanfar, Mehdi [Protein Research Center, Shahid Beheshti University, Evin 1983963113, Tehran (Iran, Islamic Republic of); Ghomi, Hamid [Laser and Plasma Research Institute, Shahid Beheshti University, Evin 1983963113, Tehran (Iran, Islamic Republic of); Ranaei-Siadat, Seyed-Omid [Protein Research Center, Shahid Beheshti University, Evin 1983963113, Tehran (Iran, Islamic Republic of)

    2015-09-15

    Highlights: • We used an economical and effective method for surface modification. • Chitosan/PEO nanofibrous membranes were modified by air-DBD plasma. • The most NH{sub 3}{sup +} group was generated on the 6 min plasma modified membrane. • We immobilized acetylcholinesterase on the plasma modified and unmodified membranes. • More enzyme activity was detected on the modified membrane by plasma. - Abstract: There are different methods to modify polymer surfaces for biological applications. In this work we have introduced air-dielectric barrier discharge (DBD) plasma at atmospheric pressure as an economical and safe method for modifying the surface of electrospun chitosan/PEO (90/10) nanofibers for acetylcholinesterase (AChE) immobilization. According to the contact angle measurement results, the nanofibers become highly hydrophilic when they are exposed to the DBD plasma for 6 min in compared to unmodified membrane. Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) results reveal hydroxyl, C=O and NH{sub 3}{sup +} polar groups increment after 6 min plasma treatment. Contact angle measurements and ATR-FTIR results are confirmed by X-ray photoelectron spectroscopy (XPS). AChE at pH 7.4 carries a negative charge and after immobilization on the surface of plasma-treated nanofibrous membrane attracts the NH{sub 3}{sup +} group and more enzyme activity is detected on the plasma-modified nanofibers for 6 min in compared to unmodified nanofibers. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) are used for the surface topography and morphology characterization. The results have proved that air-DBD plasma is a suitable method for chitosan/PEO nanofibrous membrane modification as a biodegradable and functionalized substrate for enzyme immobilization.

  20. Analysis of Ar plasma jets induced by single and double dielectric barrier discharges at atmospheric pressure

    Science.gov (United States)

    Judée, F.; Merbahi, N.; Wattieaux, G.; Yousfi, M.

    2016-09-01

    The aim is the comparison of different plasma parameters of single and double dielectric barrier discharge plasma jet configurations (S-DBD and D-DBD) which are potentially usable in biomedical applications. Both configurations are studied in terms of electric field distribution, electrical discharge characteristics, plasma parameters (estimated by optical emission spectroscopy analysis), and hydrodynamics of the plasma jet for electrical parameters of power supplies corresponding to an applied voltage of 10 kV, pulse duration of 1 μs, frequency of 9.69 kHz, and Ar flow of 2 l/min. We observed that the D-DBD configuration requires half the electrical power one needs to provide in the S-DBD case to generate a plasma jet with similar characteristics: excitation temperature around 4700 K, electron density around 2.5 × 1014 cm-3, gas temperature of about 320 K, a relatively high atomic oxygen concentration reaching up to 1000 ppm, the presence of reactive oxygen and nitrogen species (nitric oxide, hydroxyl radical, and atomic oxygen), and an irradiance in the UV-C range of about 20 μW cm-2. Moreover, it has been observed that D-DBD plasma jet is more sensitive to short pulse durations, probably due to the charge accumulation over the dielectric barrier around the internal electrode. This results in a significantly longer plasma length in the D-DBD configuration than in the S-DBD one up to a critical flow rate (2.25 l/min) before the occurrence of turbulence in the D-DBD case. Conversely, ionization wave velocities are significantly higher in the S-DBD setup (3.35 × 105 m/s against 1.02 × 105 m/s for D-DBD), probably due to the higher electrostatic field close to the high voltage electrode in the S-DBD plasma jet.

  1. Effect of dielectric and liquid on plasma sterilization using dielectric barrier discharge plasma.

    Directory of Open Access Journals (Sweden)

    Navya Mastanaiah

    Full Text Available Plasma sterilization offers a faster, less toxic and versatile alternative to conventional sterilization methods. Using a relatively small, low temperature, atmospheric, dielectric barrier discharge surface plasma generator, we achieved ≥ 6 log reduction in concentration of vegetative bacterial and yeast cells within 4 minutes and ≥ 6 log reduction of Geobacillus stearothermophilus spores within 20 minutes. Plasma sterilization is influenced by a wide variety of factors. Two factors studied in this particular paper are the effect of using different dielectric substrates and the significance of the amount of liquid on the dielectric surface. Of the two dielectric substrates tested (FR4 and semi-ceramic (SC, it is noted that the FR4 is more efficient in terms of time taken for complete inactivation. FR4 is more efficient at generating plasma as shown by the intensity of spectral peaks, amount of ozone generated, the power used and the speed of killing vegetative cells. The surface temperature during plasma generation is also higher in the case of FR4. An inoculated FR4 or SC device produces less ozone than the respective clean devices. Temperature studies show that the surface temperatures reached during plasma generation are in the range of 30°C-66 °C (for FR4 and 20 °C-49 °C (for SC. Surface temperatures during plasma generation of inoculated devices are lower than the corresponding temperatures of clean devices. pH studies indicate a slight reduction in pH value due to plasma generation, which implies that while temperature and acidification may play a minor role in DBD plasma sterilization, the presence of the liquid on the dielectric surface hampers sterilization and as the liquid evaporates, sterilization improves.

  2. Formation of radical and active chemical species in electrical discharge plasma in the presence of liquid water

    Energy Technology Data Exchange (ETDEWEB)

    Locke, B.R.; Shih, K.Y.; Burlica, R. [Florida State Univ., Tallahassee, FL (United States). Dept. of Chemical and Biomedical Engineering

    2010-07-01

    This study investigated the interactions of plasma with liquid water using a combination of emission spectroscopy of radical and atomic species and direct measurements of more stable chemical compounds. The study focused on electrical discharge plasma formed directly in liquid water and on discharges formed in the gas phase above liquid water, in bubbles in liquid water, and in the gas phase with water droplet spray that result in a variety of active chemical species that can be used for pollution control as well as other applications in biomedical and materials engineering. The purpose was to improve the design and operation of plasma reactors for a variety of applications. This presentation also reviewed the mechanisms for the formation of active chemical species such as hydroxyl and other radicals, hydrogen peroxide and molecular hydrogen, in electrical discharge plasma formed in the presence of water.

  3. Comparative study of non-thermal atmospheric pressure discharge plasmas for life science applications

    Science.gov (United States)

    Koga, Kazunori; Katayama, Ryu; Sarinont, Thapanut; Seo, Hyunwoong; Itagaki, Naho; Attri, Pankaj; Leal-Quiros, Edbertho; Tanaka, Akiyo; Shiratani, Masaharu

    2016-09-01

    We are comparing several non-thermal atmospheric pressure discharge plasmas for life science applications. Here we measured discharge period dependence of pH value and 750 nm absorbance of KI-starch solution of deionized water after plasma irradiation with two discharge devices; a dielectric barrier discharge (DBD) jet device and a scalable DBD device. The pH and the absorbance of KI-starch solution are useful indicator of their oxidizability. We have obtained a map of the absorbance and proton concentration [H+] which is deduced from pH value. For the scalable DBD, the range of the absorbance is between 0.7 and 1.3 and that of [H+] is between 10-7 and 10-5 mol/L. For the DBD jet, the range of the absorbance and [H+] are 2.0-3.2 and 10-4-10-3 mol/L, respectively. Measured data for both devices shows same tendency in the map, while the range of values for the scalable DBD is smaller than that for the DBD jet. The results indicate the oxidazability for the scalable DBD is much weaker than that for the DBD jet.

  4. Energy deposition characteristics of nanosecond dielectric barrier discharge plasma actuators: Influence of dielectric material

    Science.gov (United States)

    Correale, G.; Winkel, R.; Kotsonis, M.

    2015-08-01

    An experimental study aimed at the characterization of energy deposition of nanosecond Dielectric Barrier Discharge (ns-DBD) plasma actuators was carried out. Special attention was given on the effect of the thickness and material used for dielectric barrier. The selected materials for this study were polyimide film (Kapton), polyamide based nylon (PA2200), and silicone rubber. Schlieren measurements were carried out in quiescent air conditions in order to observe density gradients induced by energy deposited. Size of heated area was used to qualify the energy deposition coupled with electrical power measurements performed using the back-current shunt technique. Additionally, light intensity measurements showed a different nature of discharge based upon the material used for barrier, for a fixed thickness and frequency of discharge. Finally, a characterisation study was performed for the three tested materials. Dielectric constant, volume resistivity, and thermal conductivity were measured. Strong trends between the control parameters and the energy deposited into the fluid during the discharge were observed. Results indicate that efficiency of energy deposition mechanism relative to the thickness of the barrier strongly depends upon the material used for the dielectric barrier itself. In general, a high dielectric strength and a low volumetric resistivity are preferred for a barrier, together with a high heat capacitance and a low thermal conductivity coefficient in order to maximize the efficiency of the thermal energy deposition induced by an ns-DBD plasma actuator.

  5. Non-Thermal Equilibrium Atmospheric Pressure Glow-Like Discharge Plasma Jet

    Science.gov (United States)

    Chang, Zhengshi; Yao, Congwei; Zhang, Guanjun

    2016-01-01

    Non-thermal equilibrium atmospheric pressure plasma jet (APPJ) is a cold plasma source that promises various innovative applications, and the uniform APPJ is more favored. Glow discharge is one of the most effective methods to obtain the uniform discharge. Compared with the glow dielectric barrier discharge (DBD) in atmospheric pressure, pure helium APPJ shows partial characteristics of both the glow discharge and the streamer. In this paper, considering the influence of the Penning effect, the electrical and optical properties of He APPJ and Ar/NH3 APPJ were researched. A word “Glow-like APPJ” is used to characterize the uniformity of APPJ, and it was obtained that the basic characteristics of the glow-like APPJ are driven by the kHz AC high voltage. The results can provide a support for generating uniform APPJ, and lay a foundation for its applications. supported by National Natural Science Foundation of China (Nos. 51307133, 51125029, 51221005) and the Fundamental Research Funds for the Central Universities of China (Nos. xjj2012132, xkjc2013004)

  6. Degradation of Microcystin-LR by Gas-Liquid Interfacial Discharge Plasma

    Science.gov (United States)

    Xin, Qing; Zhang, Yi; Wu, Kaibin

    2013-12-01

    In this study, we report on the degradation of microcystin-LR (MC-LR) by gas-liquid interfacial discharge plasma. The influences of operation parameters such as average input voltage, electrode distance and gas flow rate are investigated. Experimental results indicate that the input voltage and gas flow rate have positive influences on MC-LR degradation, while the electrode distance has a negative one. After 6 min discharge with 25 kV average input voltage and 60 L/h air aeration, the degradation rate of MC-LR achieves 75.3%. H2O2 and O3 generated by discharge both in distilled water and MC-LR solution are measured. Moreover, an emission spectroscopy is used as an indicator of the processes that take place on the gas-liquid boundary and inside plasma. Varied types of radicals (O, ·OH, CO, O3, etc.) are proved to be present in the gas phase during gas-liquid interfacial discharge.

  7. Skeletal cell differentiation is enhanced by atmospheric dielectric barrier discharge plasma treatment.

    Directory of Open Access Journals (Sweden)

    Marla J Steinbeck

    Full Text Available Enhancing chondrogenic and osteogenic differentiation is of paramount importance in providing effective regenerative therapies and improving the rate of fracture healing. This study investigated the potential of non-thermal atmospheric dielectric barrier discharge plasma (NT-plasma to enhance chondrocyte and osteoblast proliferation and differentiation. Although the exact mechanism by which NT-plasma interacts with cells is undefined, it is known that during treatment the atmosphere is ionized generating extracellular reactive oxygen and nitrogen species (ROS and RNS and an electric field. Appropriate NT-plasma conditions were determined using lactate-dehydrogenase release, flow cytometric live/dead assay, flow cytometric cell cycle analysis, and Western blots to evaluate DNA damage and mitochondrial integrity. We observed that specific NT-plasma conditions were required to prevent cell death, and that loss of pre-osteoblastic cell viability was dependent on intracellular ROS and RNS production. To further investigate the involvement of intracellular ROS, fluorescent intracellular dyes Mitosox (superoxide and dihydrorhodamine (peroxide were used to assess onset and duration after NT-plasma treatment. Both intracellular superoxide and peroxide were found to increase immediately post NT-plasma treatment. These increases were sustained for one hour but returned to control levels by 24 hr. Using the same treatment conditions, osteogenic differentiation by NT-plasma was assessed and compared to peroxide or osteogenic media containing β-glycerolphosphate. Although both NT-plasma and peroxide induced differentiation-specific gene expression, neither was as effective as the osteogenic media. However, treatment of cells with NT-plasma after 24 hr in osteogenic or chondrogenic media significantly enhanced differentiation as compared to differentiation media alone. The results of this study show that NT-plasma can selectively initiate and amplify ROS

  8. Skeletal cell differentiation is enhanced by atmospheric dielectric barrier discharge plasma treatment.

    Science.gov (United States)

    Steinbeck, Marla J; Chernets, Natalie; Zhang, Jun; Kurpad, Deepa S; Fridman, Gregory; Fridman, Alexander; Freeman, Theresa A

    2013-01-01

    Enhancing chondrogenic and osteogenic differentiation is of paramount importance in providing effective regenerative therapies and improving the rate of fracture healing. This study investigated the potential of non-thermal atmospheric dielectric barrier discharge plasma (NT-plasma) to enhance chondrocyte and osteoblast proliferation and differentiation. Although the exact mechanism by which NT-plasma interacts with cells is undefined, it is known that during treatment the atmosphere is ionized generating extracellular reactive oxygen and nitrogen species (ROS and RNS) and an electric field. Appropriate NT-plasma conditions were determined using lactate-dehydrogenase release, flow cytometric live/dead assay, flow cytometric cell cycle analysis, and Western blots to evaluate DNA damage and mitochondrial integrity. We observed that specific NT-plasma conditions were required to prevent cell death, and that loss of pre-osteoblastic cell viability was dependent on intracellular ROS and RNS production. To further investigate the involvement of intracellular ROS, fluorescent intracellular dyes Mitosox (superoxide) and dihydrorhodamine (peroxide) were used to assess onset and duration after NT-plasma treatment. Both intracellular superoxide and peroxide were found to increase immediately post NT-plasma treatment. These increases were sustained for one hour but returned to control levels by 24 hr. Using the same treatment conditions, osteogenic differentiation by NT-plasma was assessed and compared to peroxide or osteogenic media containing β-glycerolphosphate. Although both NT-plasma and peroxide induced differentiation-specific gene expression, neither was as effective as the osteogenic media. However, treatment of cells with NT-plasma after 24 hr in osteogenic or chondrogenic media significantly enhanced differentiation as compared to differentiation media alone. The results of this study show that NT-plasma can selectively initiate and amplify ROS signaling to enhance

  9. Spectroscopic study of plasma evolution in runaway nanosecond atmospheric-pressure He discharges.

    Science.gov (United States)

    Yatom, S; Stambulchik, E; Vekselman, V; Krasik, Ya E

    2013-07-01

    Time- and space-resolved visible-emission spectroscopy measurements are applied to study plasma parameters in nanosecond electrical discharges in He gas at pressure of 10(5) Pa, using a 150 kV, 5 ns duration high-voltage pulse. The plasma evolution during the discharge is investigated by applying line-shape analysis of several He I spectral transitions, with the Stark and opacity effects accounted for. The analysis shows that the discharge plasma is not in equilibrium and that significant electric fields of several kV/cm are present in the plasma during the discharge. Regions of plasma with significantly different electron densities are identified and a qualitative model of the plasma formation and evolution is proposed.

  10. Assessment of cytotoxic effect mechanisms of gas-discharge plasma radiation

    OpenAIRE

    Ivanova I.P.; Trofimova S.V.; Vedunova М.V.; Zhabereva А.S.; Bugrova M.L.; Piskaryov I.M.; Karpel Vel Leitner N.

    2014-01-01

    The aim of the investigation was to assess the mechanisms of cytotoxic effect of gas-discharge plasma radiation on lymphosarcoma and breast cancer cells. Materials and Methods. The experiment was carried out on the strains of rat lymphosarcoma (LSR) and breast cancer (RMK1) cells. 4 ml of cell suspension at (4–6)·106/ml concentration was exposed to gas-discharge plasma radiation in various time modes. Plasma radiation was generated by impulse device with the following set characteristics:...

  11. Long-Lived Vortex Structures in Collisional Pure and Gas-Discharge Nonneutral Electron Plasmas

    OpenAIRE

    Kervalishvili, N. A.

    2013-01-01

    The analysis of experimental investigations of equilibrium, interaction and dynamics of vortex structures in pure electron and gas-discharge electron nonneutral plasmas during the time much more than the electron-neutral collision time has been carried out. The problem of long confinement of the column of pure electron plasma in Penning-Malmberg trap is considered. The mechanism of stability of long-lived vortex structure in gas-discharge nonneutral electron plasma is investigated. The collap...

  12. Diagnostics of Atmospheric Pressure Surface Discharge Plasmas in Argon

    Institute of Scientific and Technical Information of China (English)

    张锐; 詹如娟; 温晓辉

    2003-01-01

    Atmospheric pressure surface discharge is shown to have great prospects for a number of industrial applications.To acquire better results in application fields and considering that the study of the basic parameters including electron temperature and electron density is desirable,we develop an equivalent circuit model and the diagnostic techniques based on optical emission spectroscopy and electrical measurement in our laboratory.The electron temperature has been determined to be about 0.7eV by a Fermi-Dirac model.The electron density has been calculated to be near 1010 cm-3 from a time resolved electrical measurement(Ohmic heating method).

  13. Three-dimensional modeling of the neutral gas depletion effect in a helicon discharge plasma

    Science.gov (United States)

    Kollasch, Jeffrey; Schmitz, Oliver; Norval, Ryan; Reiter, Detlev; Sovinec, Carl

    2016-10-01

    Helicon discharges provide an attractive radio-frequency driven regime for plasma, but neutral-particle dynamics present a challenge to extending performance. A neutral gas depletion effect occurs when neutrals in the plasma core are not replenished at a sufficient rate to sustain a higher plasma density. The Monte Carlo neutral particle tracking code EIRENE was setup for the MARIA helicon experiment at UW Madison to study its neutral particle dynamics. Prescribed plasma temperature and density profiles similar to those in the MARIA device are used in EIRENE to investigate the main causes of the neutral gas depletion effect. The most dominant plasma-neutral interactions are included so far, namely electron impact ionization of neutrals, charge exchange interactions of neutrals with plasma ions, and recycling at the wall. Parameter scans show how the neutral depletion effect depends on parameters such as Knudsen number, plasma density and temperature, and gas-surface interaction accommodation coefficients. Results are compared to similar analytic studies in the low Knudsen number limit. Plans to incorporate a similar Monte Carlo neutral model into a larger helicon modeling framework are discussed. This work is funded by the NSF CAREER Award PHY-1455210.

  14. Gene Transfection Method Using Atmospheric Pressure Dielectric-Barrier Discharge Plasmas

    Science.gov (United States)

    Sasaki, Shota; Kanzaki, Makoto; Kaneko, Toshiro

    2013-09-01

    Gene transfection which is the process of deliberately introducing nucleic acids into cells is expected to play an important role in medical treatment because the process is necessary for gene therapy and creation of induced pluripotent stem (iPS) cells. However, the conventional transfection methods have some problems, so we focus attention on promising transfection methods by atmospheric pressure dielectric-barrier discharge (AP-DBD) plasmas. AP-DBD He plasmas are irradiated to the living cell covered with genes. Preliminarily, we use fluorescent dye YOYO-1 instead of the genes and use LIVE/DEAD Stain for cell viability test, and we analyze the transfection efficiency and cell viability under the various conditions. It is clarified that the transfection efficiency is strongly dependence on the plasma irradiation time and cell viability rates is high rates (>90%) regardless of long plasma irradiation time. These results suggest that ROS (Reactive Oxygen Species) and electric field generated by the plasma affect the gene transfection. In addition to this (the plasma irradiation time) dependency, we now investigate the effect of the plasma irradiation under the various conditions.

  15. Degradation of triclosan in aqueous solution by dielectric barrier discharge plasma combined with activated carbon fibers.

    Science.gov (United States)

    Xin, Lu; Sun, Yabing; Feng, Jingwei; Wang, Jian; He, Dong

    2016-02-01

    The degradation of triclosan (TCS) in aqueous solution by dielectric barrier discharge (DBD) plasma with activated carbon fibers (ACFs) was investigated. In this study, ACFs and DBD plasma coexisted in a planar DBD plasma reactor, which could synchronously achieve degradation of TCS, modification and in situ regeneration of ACFs, enhancing the effect of recycling of ACFs. The properties of ACFs before and after modification by DBD plasma were characterized by BET and XPS. Various processing parameters affecting the synergetic degradation of TCS were also investigated. The results exhibited excellent synergetic effects in DBD plasma-ACFs system on TCS degradation. The degradation efficiency of 120 mL TCS with initial concentration of 10 mg L(-1) could reach 93% with 1 mm thick ACFs in 18 min at input power of 80 W, compared with 85% by single DBD plasma. Meanwhile, the removal rate of total organic carbon increased from 12% at pH 6.26-24% at pH 3.50. ACFs could ameliorate the degradation efficiency for planar DBD plasma when treating TCS solution at high flow rates or at low initial concentrations. A possible degradation pathway of TCS was investigated according to the detected intermediates, which were identified by liquid chromatography-hybrid quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) combined with theoretical calculation of Gaussian 09 program.

  16. Physics and Chemistry of MW Laser-induced Discharge in Gas Flows and Plasma Jets

    Science.gov (United States)

    2007-12-01

    can be quasi-stationary coaxial plasma accelerators (MPC). This type of accelerators generates plasma jets of different gases (H2, He, N2, Ar) with...gas is ionizing and accelerating in discharge processing. For this regime the plasma gun generates the plasma jets of different gases3 (H2, He, N2...spectrometers. Spectrometers 1 and 2 are used for measuring of time behavior of single spectral lines, emitting in the focus area of plasma gun . Usually

  17. Feasibility of arc-discharge and plasma-sputtering methods in cleaning plasma-facing and diagnostics components of fusion reactors

    Energy Technology Data Exchange (ETDEWEB)

    Hakola, Antti, E-mail: antti.hakola@vtt.fi [VTT Technical Research Centre of Finland, VTT (Finland); Likonen, Jari [VTT Technical Research Centre of Finland, VTT (Finland); Karhunen, Juuso; Korhonen, Juuso T. [Department of Applied Physics, Aalto University (Finland); Aints, Märt; Laan, Matti; Paris, Peeter [Department of Physics, University of Tartu (Estonia); Kolehmainen, Jukka; Koskinen, Mika; Tervakangas, Sanna [DIARC-Technology Oy, Espoo (Finland)

    2015-10-15

    Highlights: • Feasibility of the arc-discharge and plasma-sputtering techniques in removing deposited layers from ITER-relevant samples demonstrated. • Samples with the size of an A4 paper can be cleaned from 1-μm thick deposited layers in 10–20 minutes by the arc-discharge method. • The plasma-sputtering method is 5–10 times slower but the resulting surfaces are very smooth. • Arc-discharge method could be used for rapid cleaning of plasma-facing components during maintenance shutdowns of ITER, plasma sputtering is preferred for diagnostics mirrors. - Abstract: We have studied the feasibility of arc-discharge and plasma-sputtering methods in removing deposited layers from ITER-relevant test samples. Prototype devices have been designed and constructed for the experiments and the cleaning process is monitored by a spectral detection system. The present version of the arc-discharge device is capable of removing 1-μm thick layers from 350-mm{sup 2} areas in 4–8 s, but due to the increased roughness of the cleaned surfaces and signs of local melting, mirror-like surfaces cannot be treated by this technique. The plasma-sputtering approach, for its part, is some 5–10 times slower in removing the deposited layers but no changes in surface roughness or morphology of the samples could be observed after the cleaning phase. The arc-discharge technique could therefore be used for rapid cleaning of plasma-facing components during maintenance shutdowns of ITER while in the case of diagnostics mirrors plasma sputtering is preferred.

  18. The component content of active particles in a plasma-chemical reactor based on volume barrier discharge

    Science.gov (United States)

    Soloshenko, I. A.; Tsiolko, V. V.; Pogulay, S. S.; Terent'yeva, A. G.; Bazhenov, V. Yu; Shchedrin, A. I.; Ryabtsev, A. V.; Kuzmichev, A. I.

    2007-02-01

    In this paper the results of theoretical and experimental studies of the component content of active particles formed in a plasma-chemical reactor composed of a multiple-cell generator of active particles, based on volume barrier discharge, and a working chamber are presented. For calculation of the content of uncharged plasma components an approach is proposed which is based on averaging of the power introduced over the entire volume. Advantages of such an approach lie in an absence of fitting parameters, such as the dimensions of microdischarges, their surface density and rate of breakdown. The calculation and the experiment were accomplished with the use of dry air (20% relative humidity) as the plasma generating medium. Concentrations of O3, HNO3, HNO2, N2 O5 and NO3 were measured experimentally in the discharge volume and working chamber for the residence time of particles on a discharge of 0.3 s and more and discharge specific power of 1.5 W cm-3. It has been determined that the best agreement between the calculation and the experiment occurs at calculated gas medium temperatures in the discharge plasma of about 400-425 K, which correspond to the experimentally measured rotational temperature of nitrogen. In most cases the calculated concentrations of O3, HNO3, HNO2, N2O5 and NO3 for the barrier discharge and the working chamber are in fairly good agreement with the respective measured values.

  19. Modeling a short cold cathode DC discharge device with controllable plasma parameters

    Science.gov (United States)

    Kudryavtsev, Anatoly; Adams, Steven; Demidov, Vladimir; Bogdanov, Yevgeny

    2009-11-01

    A short (without positive column) DC gas-discharge device with a cold cathode has been modeled. The device consists of the plane disk-shaped cathode and anode while the inter-electrode gap is bounded by a cylindrical wall. The cathode and anode are each 2.5 cm in diameter, and the inter-electrode gap is 12 mm. The wall is made of conducting parts divided by an insulator. The modeling has been performed for argon plasma at 1 Torr pressure. It is demonstrated in the model that spatial distributions of electron density and temperature and argon metastable atom density depend on the DC voltage applied to different conducting parts of the wall. Applied voltage can trap within the device volume energetic electrons arising from atomic and molecular processes in the plasma. This leads to a modification in the heating of slow electrons by energetic electrons and as a result modifies the controlling plasma parameters.

  20. A low power miniaturized dielectric barrier discharge based atmospheric pressure plasma jet

    Science.gov (United States)

    Divya Deepak, G.; Joshi, N. K.; Pal, Dharmendra Kumar; Prakash, Ram

    2017-01-01

    In this paper, a dielectric barrier discharge plasma based atmospheric pressure plasma jet has been generated in a floating helix and floating end ring electrode configuration using argon and helium gases. This configuration is subjected to a range of supply frequencies (10-25 kHz) and supply voltages (2-6 kV) at a fixed rate of gas flow rate (i.e., 1 l/min). The electrical characterization of the plasma jet has been carried out using a high voltage probe and current transformer. The current-voltage characteristics have been analyzed, and the consumed power has been estimated at different applied combinations for optimum power consumption at maximum jet length. The obtained optimum power and jet length for argon and helium gases are 12 mW and 32 mm, and 7.7 mW and 42 mm, respectively. It is inferred that besides the electrode configurations, the discharge gas is also playing a significant role in the low power operation of the cold plasma jet at maximum jet length. The obtained results are interpreted on the basis of penning processes.

  1. Investigation of Vortex Structures in Gas-Discharge Nonneutral Electron Plasma: I. Experimental Technique

    CERN Document Server

    Kervalishvili, N A

    2015-01-01

    The nonperturbing experimental methods have been described, by means of which the solitary vortex structures in gas-discharge nonneutral electron plasma were detected and investigated. The comparison with the experimental methods used in devices with pure electron plasma was made. The problems of shielding the electrostatic perturbations in nonneutral plasmas were considered.

  2. Nanosecond Pulsed Discharge in Water without Bubbles: A Fundamental Study of Initiation, Propagation and Plasma Characteristics

    Science.gov (United States)

    Seepersad, Yohan

    The state of plasma is widely known as a gas-phase phenomenon, but plasma in liquids have also received significant attention over the last century. Generating plasma in liquids however is theoretically challenging, and this problem is often overcome via liquid-gas phase transition preceding the actual plasma formation. In this sense, plasma forms in gas bubbles in the liquid. Recent work at the Drexel Plasma Institute has shown that nanosecond pulsed electric fields can initiate plasma in liquids without any initial cavitation phase, at voltages below theoretical direct-ionization thresholds. This unique regime is poorly understood and does not fit into any current descriptive mechanisms. As with all new phenomena, a complete fundamental description is paramount to understanding its usefulness to practical applications. The primary goals of this research were to qualitatively and quantitatively understand the phenomenon of nanosecond pulsed discharge in liquids as a means to characterizing properties that may open up niche application possibilities. Analysis of the plasma was based on experimental results from non-invasive, sub-nanosecond time-resolved optical diagnostics, including direct imaging, transmission imaging (Schlieren and shadow), and optical emission spectroscopy. The physical characteristics of the plasma were studied as a function of variations in the electric field amplitude and polarity, liquid permittivity, and pulse duration. It was found that the plasma size and emission intensity was dependent on the permittivity of the liquid, as well as the voltage polarity, and the structure and dynamics were explained by a 'cold-lightning' mechanism. The under-breakdown dynamics at the liquid-electrode interface were investigated by transmission imaging to provide evidence for a novel mechanism for initiation based on the electrostriction. This mechanism was proposed by collaborators on the project and developed alongside the experimental work in this

  3. Reactivity of water vapor in an atmospheric argon flowing post-discharge plasma torch

    CERN Document Server

    Collette, S; Reniers, F

    2016-01-01

    The reactivity of water vapor introduced in the flowing post-discharge of an RF atmospheric plasma torch is investigated through electrical characterization, optical emission spectroscopy and mass spectrometry measurements. Due to the technical features of the plasma torch, the post-discharge can be considered as divided into two regions: an inner region (inside the plasma torch device) where the water vapor is injected and an outer region which directly interacts with the ambient air. The main reactions induced by the injection of water vapor are identified as well as those indicative of the influence of the ambient air. Plausible pathways allowing the production of H, OH, O radicals and H2O2 are discussed as well as reactions potentially responsible for inhomogeneities and for a low DC current measured in the flowing post-discharge. Keywords: atmospheric post-discharge, H2O plasma reactivity, RF plasma torch

  4. Plasma inactivation of microorganisms on sprout seeds in a dielectric barrier discharge.

    Science.gov (United States)

    Butscher, Denis; Van Loon, Hanne; Waskow, Alexandra; Rudolf von Rohr, Philipp; Schuppler, Markus

    2016-12-05

    Fresh produce is frequently contaminated by microorganisms, which may lead to spoilage or even pose a threat to human health. In particular sprouts are considered to be among the most risky foods sold at retail since they are grown in an environment practically ideal for growth of bacteria and usually consumed raw. Because heat treatment has a detrimental effect on the germination abilities of sprout seeds, alternative treatment technologies need to be developed for microbial inactivation purposes. In this study, non-thermal plasma decontamination of sprout seeds is evaluated as a promising option to enhance food safety while maintaining the seed germination capabilities. In detail, investigations focus on understanding the efficiency of non-thermal plasma inactivation of microorganisms as influenced by the type of microbial contamination, substrate surface properties and moisture content, as well as variations in the power input to the plasma device. To evaluate the impact of these parameters, we studied the reduction of native microbiota or artificially applied E. coli on alfalfa, onion, radish and cress seeds exposed to non-thermal plasma in an atmospheric pressure pulsed dielectric barrier discharge streamed with argon. Plasma treatment resulted in a maximum reduction of 3.4 logarithmic units for E. coli on cress seeds. A major challenge in plasma decontamination of granular food products turned out to be the complex surface topology, where the rough surface with cracks and crevices can shield microorganisms from plasma-generated reactive species, thus reducing the treatment efficiency. However, improvement of the inactivation efficiency was possible by optimizing substrate characteristics such as the moisture level and by tuning the power supply settings (voltage, frequency) to increase the production of reactive species. While the germination ability of alfalfa seeds was considerably decreased by harsh plasma treatment, enhanced germination was observed under

  5. Modelling of a water plasma flow: I. Basic results

    Energy Technology Data Exchange (ETDEWEB)

    KotalIk, Pavel [INP Greifswald, Friedrich-Ludwig-Jahn-Strasse 19, 17489 Greifswald (Germany)

    2006-06-21

    One-fluid MHD equations are numerically solved for an axisymmetric flow of thermal water plasma inside and outside a discharge chamber of a plasma torch with water vortex stabilization of electric arc. Comparisons with experimental data and previous calculations are given. For arc currents of 300-600 A, the respective temperatures and velocities in the range 16 700-26 400 K and 2300-6900 m s{sup -1} are obtained at the centre of the nozzle exit. The flow velocity on axis increases by 1-2 km s{sup -1} in the 5 mm long nozzle. Ohmic heating and radiative losses are two competitive processes influencing most the plasma temperature and velocity. The radiative losses represent 39% to 46% of the torch power of 69-174 kW when optical thickness of 3 mm is assumed for the plasma column. In front of the cathode, inside the discharge chamber, a recirculation zone is predicted and discussed. Effects of the temperature dependence of the plasma viscosity and sound velocity and of the optical thickness are examined. It is shown that the results such as waviness of the Mach number isolines are direct consequences of these dependences. Different lengths of 55 and 60 mm of the water vortex stabilized part of the electric arc do not substantially influence the plasma temperature and velocity at the nozzle exit.

  6. Operation circuits of emissive probes for determination of potentials in discharge plasmas; Circuitos de operacao de sondas emissivas para a determinacao de potenciais em plasmas de descargas eletricas

    Energy Technology Data Exchange (ETDEWEB)

    Petraconi, G.; Maciel, H.S.; Borges, C. [Centro Tecnico Aeroespacial, Sao Jose dos Campos, SP (Brazil). Inst. Tecnologico de Aeronautica. Lab. de Plasmas e Processos

    1999-12-01

    In this paper two circuits for plasma potential measurement are presented. The first one is an emissive probe control circuit for fast probe characteristics reading. The second one is a differential emissive probe control circuit that adjusts the bias voltage automatically and allows a direct potential measurement. These circuits present inconveniences if the characteristic of the probe does not exhibit an ideal saturation of the current as show the results obtained in continuous current discharge and RF discharge. (author)

  7. Particle Densities of the Atmospheric-Pressure Argon Plasmas Generated by the Pulsed Dielectric Barrier Discharges

    Science.gov (United States)

    Pan, Jie; Li, Li; Wang, Yunuan; Xiu, Xianwu; Wang, Chao; Song, Yuzhi

    2016-11-01

    Atmospheric-pressure argon plasmas have received increasing attention due to their high potential in many industrial and biomedical applications. In this paper, a 1-D fluid model is used for studying the particle density characteristics of the argon plasmas generated by the pulsed dielectric barrier discharges. The temporal evolutions of the axial particle density distributions are illustrated, and the influences of changing the main discharge conditions on the averaged particle densities are researched by independently varying the various discharge conditions. The calculation results show that the electron density and the ion density reach two peaks near the momentary cathodes during the rising and the falling edges of the pulsed voltage. Compared with the charged particle densities, the densities of the resonance state atom Arr and the metastable state atom Arm have more uniform axial distributions, reach higher maximums and decay more slowly. During the platform of the pulsed voltage and the time interval between the pulses, the densities of the excited state atom Ar* are far lower than those of the Arr or the Arm. The averaged particle densities of the different considered particles increase with the increases of the amplitude and the frequency of the pulsed voltage. Narrowing the discharge gap and increasing the relative dielectric constant of the dielectric also contribute to the increase of the averaged particle densities. The effects of reducing the discharge gap distance on the neutral particle densities are more significant than the influences on the charged particle densities. supported by Natural Science Foundation of Shandong Province, China (No. ZR2015AQ008), and Project of Shandong Province Higher Educational Science and Technology Program of China (No. J15LJ04)

  8. An experimental study on discharge characteristics in a pulsed-dc atmospheric pressure CH3OH/Ar plasma jet

    Science.gov (United States)

    Qian, Muyang; Liu, Sanqiu; Yang, Congying; Pei, Xuekai; Lu, Xinpei; Zhang, Jialiang; Wang, Dezhen

    2016-10-01

    Recently, C/H/Ar plasma discharges found enormous potential and possibility in carbonaceous compounds conversion and production. In this work, a pulsed-dc CH3OH/Ar plasma jet generated at atmospheric pressure is investigated by means of optical and electrical diagnosis concerning the variation of its basic parameters, absolute concentration of OH radicals, and plasma temperature with different CH3OH/Ar volume ratios, in the core region of discharge with needle-to-ring electrode configuration. The voltage-current characteristics are also measured at different CH3OH/Ar ratios. Laser-induced fluorescence (LIF) results here show that only small amounts of added methanol vapor to argon plasma (about 0.05% CH3OH/Ar volume ratio) is favorable for the production of OH radicals. The optical emission lines of CH, CN, and C2 radicals have been detected in the CH3OH/Ar plasma. And, the plasma temperatures increase with successive amount of added methanol vapor to the growth plasma. Moreover, qualitative discussions are presented regarding the mechanisms for methanol dissociation and effect of the CH3OH component on the Ar plasma discharge at atmospheric pressure.

  9. Plasma characteristics of argon glow discharge produced by AC power supply operating at low frequencies

    Energy Technology Data Exchange (ETDEWEB)

    Kongpiboolkid, Watcharapon; Mongkolnavin, Rattachat [Department of Physics, Facuty of Science, Chulalongkorn University, Bangkok (Thailand); Plasma Technology and Nuclear Fusion Research Unit, Chulalongkorn University, Bangkok (Thailand)

    2015-04-24

    Non-thermal properties of Argon glow discharge operating with various operating pressures were measured and presented in this work. The Argon plasma is produced by a parallel conducting electrodes coupling with a high voltage AC power supply. The power supply can generate high AC voltage at various frequencies. The frequencies for the operation are in the range of a few kHz. The system is capable of generating electric field between the two metal electrodes discharge system. The characteristics of plasma produced were measured by optical emission spectroscopy (OES) technique where electron temperature (T{sub e}) and electron number density (n{sub e}) can be determined by line intensity ratio method. The value of electron number density was then determined from the Saha-Eggert equation. Our results show that the electron number density of the discharge obtained is of the order of 10{sup −17} − 10{sup −18} m{sup −3} where the electron temperature is between 1.00−2.00 eV for various operating frequencies used which are in good agreement with similar results published earlier.

  10. Control of endwall secondary flow in a compressor cascade with dielectric barrier discharge plasma actuation

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Three dielectric barrier discharge plasma actuators were mounted at the positions of 20%,40%and 60%of chord length on the endwall in a compressor cascade.The downstream flow field of the cascade has been measured with a mini five-hole pressure probe with and without the plasma actuation.The measured results show that the plasma actuation most effectively reduces total pressure loss and flow blockage when the actuators are operated simultaneously.As each of the actuators is operated independently,the actuator at the position of 20%of chord length most effectively reduces flow blockage, and the actuator at the position of 60%of chord length fairly reduces total pressure loss.However, negative pressure loss reduction occurs with the plasma actuator at the position of 40%of chord length.In brief,the plasma actuation placed on the endwall in the cascade apparently influences the endwall secondary flow,and the optimal locations and strength of actuation are critical for the control of endwall secondary flow in a compressor cascade with the plasma actuators.

  11. Inactivation of soybean trypsin inhibitor by dielectric-barrier discharge (DBD) plasma.

    Science.gov (United States)

    Li, Junguang; Xiang, Qisen; Liu, Xiufang; Ding, Tian; Zhang, Xiangsheng; Zhai, Yafei; Bai, Yanhong

    2017-10-01

    Soybean trypsin inhibitor (STI) is considered as one of the most important anti-nutritional factors in soybeans. The objective of this study was to investigate the impacts and underling mechanisms of dielectric-barrier discharge (DBD) plasma on STI activities. The results shown that DBD plasma treatment significantly induced the inactivation of STI in soymilk and Kunitz-type trypsin inhibitor from soybean (SKTI) in a model system. After exposure to DBD plasma at 51.4W for 21min, the STI activities of soymilk were reduced by 86.1%. Affter being treated by DBD plasma, the intrinsic fluorescence and surface hydrophobicity of SKTI were significantly decreased, while the sulfhydryl contents were increased. It is assumed that DBD plasma-induced conformational changes and oxidative modification might contribute to the inactivation of SKTI. In summary, DBD plasma technology is a potential alternative to heat treatment for the inactivation of anti-nutritional substances in food legumes. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Gas discharge plasmas are effective in inactivating Bacillus and Clostridium spores.

    Science.gov (United States)

    Tseng, Shawn; Abramzon, Nina; Jackson, James O; Lin, Wei-Jen

    2012-03-01

    Bacterial spores are the most resistant form of life and have been a major threat to public health and food safety. Nonthermal atmospheric gas discharge plasma is a novel sterilization method that leaves no chemical residue. In our study, a helium radio-frequency cold plasma jet was used to examine its sporicidal effect on selected strains of Bacillus and Clostridium. The species tested included Bacillus subtilis, Bacillus stearothermophilus, Clostridium sporogenes, Clostridium perfringens, Clostridium difficile, and Clostridium botulinum type A and type E. The plasmas were effective in inactivating selected Bacillus and Clostridia spores with D values (decimal reduction time) ranging from 2 to 8 min. Among all spores tested, C. botulinum type A and C. sporogenes were significantly more resistant to plasma inactivation than other species. Observations by phase contrast microscopy showed that B. subtilis spores were severely damaged by plasmas and the majority of the treated spores were unable to initiate the germination process. There was no detectable fragmentation of the DNA when the spores were treated for up to 20 min. The release of dipicolinic acid was observed almost immediately after the plasma treatment, indicating the spore envelope damage could occur quickly resulting in dipicolinic acid release and the reduction of spore resistance.

  13. Comparison Between Dielectric Barrier Discharge Plasma and Ozone Regenerations of Activated Carbon Exhausted with Pentachlorophenol

    Science.gov (United States)

    Qu, Guangzhou; Liang, Dongli; Qu, Dong; Huang, Yimei; Li, Jie

    2014-06-01

    In this study, two regeneration methods (dielectric barrier discharge (DBD) plasma and ozone (O3) regeneration) of saturated granular activated carbon (GAC) with pentachlorophenol (PCP) were compared. The results show that the two regeneration methods can eliminate contaminants from GAC and recover its adsorption properties to some extent. Comparing the DBD plasma with O3 regeneration, the adsorption rate and the capacity of the GAC samples after DBD plasma regeneration are greater than those after O3 regeneration. O3 regeneration decreases the specific surface area of GAC and increases the acidic surface oxygen groups on the surface of GAC, which causes a decrease in PCP on GAC uptake. With increasing regeneration cycles, the regeneration efficiencies of the two methods decrease, but the decrease in the regeneration efficiencies of GAC after O3 regeneration is very obvious compared with that after DBD plasma regeneration. Furthermore, the equilibrium data were fitted by the Freundlich and Langmuir models using the non-linear regression technique, and all the adsorption equilibrium isotherms fit the Langmuir model fairly well, which demonstrates that the DBD plasma and ozone regeneration processes do not appear to modify the adsorption process, but to shift the equilibrium towards lower adsorption concentrations. Analyses of the weight loss of GAC show that O3 regeneration has a lower weight loss than DBD plasma regeneration.

  14. Product surface hardening in non-self-sustained glow discharge plasma before synthesis of superhard coatings

    Science.gov (United States)

    Krasnov, P. S.; Metel, A. S.; Nay, H. A.

    2017-05-01

    Before the synthesis of superhard coating, the product surface is hardened by means of plasma nitriding, which prevents the surface deformations and the coating brittle rupture. The product heating by ions accelerated from plasma by applied to the product bias voltage leads to overheating and blunting of the product sharp edges. To prevent the blunting, it is proposed to heat the products with a broad beam of fast nitrogen molecules. The beam injection into a working vacuum chamber results in filling of the chamber with quite homogeneous plasma suitable for nitriding. Immersion in the plasma of the electrode and heightening of its potential up to 50-100 V initiate a non-self-sustained glow discharge between the electrode and the chamber. It enhances the plasma density by an order of magnitude and reduces its spatial nonuniformity down to 5-10%. When a cutting tool is isolated from the chamber, it is bombarded by plasma ions with an energy corresponding to its floating potential, which is lower than the sputtering threshold. Hence, the sharp edges are sputtered only by fast nitrogen molecules with the same rate as other parts of the tool surface. This leads to sharpening of the cutting tools instead of blunting.

  15. Effect of Electric Discharge on Properties of Nano-Particulate Catalyst for Plasma-Catalysis.

    Science.gov (United States)

    Lee, Chung Jun; Kim, Jip; Kim, Taegyu

    2016-02-01

    Heterogeneous catalytic processes have been used to produce hydrogen from hydrocarbons. However, high reforming temperature caused serious catalyst deteriorations and low energy efficiency. Recently, a plasma-catalyst hybrid process was used to reduce the reforming temperature and to improve the stability and durability of reforming catalysts. Effect of electric discharges on properties of nanoparticulate catalysts for plasma-catalysis was investigated in the present study. Catalyst-bed porosity was varied by packing catalyst beads with the different size in a reactor. Discharge power and onset voltage of the plasma were measured as the catalyst-bed porosity was varied. The effect of discharge voltage, frequency and voltage waveforms such as the sine, pulse and square was investigated. We found that the optimal porosity of the catalyst-bed exists to maximize the electric discharge. At a low porosity, the electric discharge was unstable to be sustained because the space between catalysts got narrow nearly close to the sheath region. On the other hand, at a high porosity, the electric discharge became weak because the plasma was not sufficient to interact with the surface of catalysts. The discharge power increased as the discharge voltage and frequency increased. The square waveform was more efficient than the sine and pulse one. At a high porosity, however, the effect of the voltage waveform was not considerable because the space between catalysts was too large for plasma to interact with the surface of catalysts.

  16. Laser diagnostics on atmospheric pressure discharge plasmas, including cryoplasmas, in environments around room and cryogenic temperature

    Science.gov (United States)

    Sakakibara, Noritaka; Muneoka, Hitoshi; Urabe, Keiichiro; Yasui, Ryoma; Sakai, Osamu; Terashima, Kazuo

    2017-04-01

    Cryoplasmas, the plasma gas temperature (T g) of which can be controlled continuously below room temperature, show various unique and advantageous properties depending on T g. Recently, the T g dependence of plasma chemistry related to metastable helium (Hem) has been revealed in helium cryoplasmas. However, T g was only estimated by thermal calculation from the temperature outside the plasmas. In this study, for better evaluation of T g, near-infrared laser heterodyne interferometry (NIR-LHI) measurements were conducted in atmospheric pressure helium pulsed discharge plasmas at around room and cryogenic ambient temperatures (T a). The maximum difference between T g and T a was evaluated as 47 K at T a  =  300 K with 282 mW power consumption. To further investigate the T g dependence of plasma chemical reactions related to Hem, laser absorption spectroscopy (LAS) was performed on the same discharge plasmas to measure the Hem density and lifetime. The Hem lifetime was longer at lower T g, i.e. the lifetime at T g  =  145 K (9.6 µs) was seven times longer than that at T g  =  386 K (1.4 µs). By comparing the results with the numerically simulated rates of Hem quenching reactions taking T g into account, the mechanism of the Hem quenching reaction was revealed to vary with T g even though the main quenching reaction was a three-body collision at all T g. In this manner, the combination of NIR-LHI with LAS led directly to the T g dependence of Hem quenching reactions.

  17. Electron density measurement in gas discharge plasmas by optical and acoustic methods

    Science.gov (United States)

    Biagioni, A.; Anania, M. P.; Bellaveglia, M.; Chiadroni, E.; Cianchi, A.; Di Giovenale, D.; Di Pirro, G.; Ferrario, M.; Filippi, F.; Mostacci, A.; Pompili, R.; Shpakov, V.; Vaccarezza, C.; Villa, F.; Zigler, A.

    2016-08-01

    Plasma density represents a very important parameter for both laser wakefield and plasma wakefield acceleration, which use a gas-filled capillary plasma source. Several techniques can be used to measure the plasma density within a capillary discharge, which are mainly based on optical diagnostic methods, as for example the well-known spectroscopic method using the Stark broadening effect. In this work, we introduce a preliminary study on an alternative way to detect the plasma density, based on the shock waves produced by gas discharge in a capillary. Firstly, the measurements of the acoustic spectral content relative to the laser-induced plasmas by a solid target allowed us to understand the main properties of the acoustic waves produced during this kind of plasma generation; afterwards, we have extended such acoustic technique to the capillary plasma source in order to calibrate it by comparison with the stark broadening method.

  18. Degradation of Benzene by Using a Silent-Packed Bed Hybrid Discharge Plasma Reactor

    Science.gov (United States)

    Jiang, Nan; Lu, Na; Li, Jie; Wu, Yan

    2012-02-01

    In this work, a novel gas phase silent-packed bed hybrid discharge plasma reactor has been proposed, and its ability to control a simulative gas stream containing 240 ppm benzene is experimentally investigated. In order to optimize the geometry of the reactor, the benzene conversion rate and energy yield (EY) were compared for various inner electrode diameters and quartz tube shapes and sizes. In addition, benzene removal efficiency in different discharge regions was qualitatively analyzed and the gas parameter (space velocity) was systematically studied. It has been found that silent-packed bed hybrid discharge plasma reactor can effectively decompose benzene. Benzene removal proved to achieve an optimum value of 60% with a characteristic energy density of 255 J/L in this paper with a 6 mm bolt high-voltage electrode and a 13 mm quartz tube. The optimal space velocity was 188.1 h-1, which resulted in moderate energy yield and removal efficiency. Reaction by-products such as hydroquinone, heptanoic acid, 4-nitrocatechol, phenol and 4-phenoxy-phenol were identified by mean of GC-MS. In addition, based on these organic by-products, a benzene destruction pathway was proposed.

  19. Conditions for uniform impact of the plasma of a runaway-electron-induced pulsed diffuse discharge on an anode

    Science.gov (United States)

    Erofeev, M. V.; Baksht, E. Kh.; Burachenko, A. G.; Tarasenko, V. F.

    2015-09-01

    The subject matters in this work are (i) the spatial structure of a volume (diffuse) discharge initiated in atmospheric-pressure air in a heavily nonuniform electric field by nanosecond voltage pulses and (ii) the influence of its plasma on the surface of a plane aluminum anode. It is shown that a diffuse discharge initiated by nanosecond voltage pulses makes it possible to uniformly process the anode's surface in atmospheric-pressure air in contrast to a spark discharge, which results in microcracking, locally changes the surface properties, and thereby degrades the surface.

  20. Biological and Agricultural Studies on Application of Discharge Plasma and Electromagnetic Fields 4. Destruction of Weeds by High Voltage Discharge

    Science.gov (United States)

    Mizuno, Akira

    In an attempt to replace chemicals for weed control, high voltage spark discharge has been applied. With the application of high voltage, discharge takes place, and current flows through the stem and root. Microscopic observation indicates that cells are damaged. The electrical resistance of the damage plant’s stems and roots decreased significantly. Several different types of apparatus were constructed, and field test results show the effectiveness of electrical discharge for weed control.

  1. Analysis of Physics Processes in the AC Plasma Torch Discharge under High Pressure

    Science.gov (United States)

    Safronov, A. A.; Vasilieva, O. B.; Dudnik, J. D.; E Kuznetsov, V.; Kuchina, J. A.; Shiryaev, V. N.; Pavlov, A. V.

    2017-04-01

    The paper is devoted to investigation of electrophysical processes in the electric discharge generated by a three-phase AC plasma torch when using a high pressure inert working gas. AC plasma torch design with end electrodes intended for work on inert gases at pressures up to 81 bar is studied. Current-voltage characteristics for different gas flow rates and pressures are presented. Physical processes characteristics of the arising voltage ripples which depend on various working parameters of the plasma torch have been investigated. Arc burning processes in the electric discharge chamber of the three-phase AC plasma torch at various working parameters were photographed.

  2. Micronucleus formation induced by dielectric barrier discharge plasma exposure in brain cancer cells

    Science.gov (United States)

    Kaushik, Nagendra K.; Uhm, Hansup; Ha Choi, Eun

    2012-02-01

    Induction of micronucleus formation (cytogenetic damage) in brain cancer cells upon exposure of dielectric barrier discharge plasma has been investigated. We have investigated the influence of exposure and incubation times on T98G brain cancer cells by using growth kinetic, clonogenic, and micronucleus formation assay. We found that micronucleus formation rate directly depends on the plasma exposure time. It is also shown that colony formation capacity of cells has been inhibited by the treatment of plasma at all doses. Cell death and micronucleus formation are shown to be significantly elevated by 120 and 240 s exposure of dielectric barrier discharge plasma.

  3. Breakdown transient study of plasma distributions in a 2.45 GHz hydrogen discharge

    Energy Technology Data Exchange (ETDEWEB)

    Cortázar, O.D., E-mail: daniel.cortazar@uclm.es [Universidad de Castilla-La Mancha, ETSII-INEI, Applied Mechanics and Projects Department, C.J. Cela s/n, 13170 Ciudad Real (Spain); Megía-Macías, A. [ESS Bilbao Consortium, Polígono Ugaldeguren-III Pol. A 7B, 48170-Zamudio, Vizcaya (Spain); Tarvainen, O.; Koivisto, H. [University of Jyväskylä, Department of Physics, PO Box 35 (YFL), 40500 Jyväskylä (Finland)

    2015-05-01

    Plasma distribution transients associated with the breakdown of a 2.45 GHz hydrogen discharge similar to high current microwave ion sources are studied by means of an ultra-fast frame image acquisition system in visible light range. Eight different plasma distributions have been studied by photographing the 2D projections of the discharge through a transparent plasma electrode. The temporal evolution of images in Balmer-alpha and Fulcher band wavelengths have been recorded associated to atomic and molecular excitation and ionization processes. Some unexpected plasma distributions transient behaviors during breakdown are reported.

  4. Interplay of discharge and gas flow in atmospheric pressure plasma jets

    Science.gov (United States)

    Jiang, Nan; Yang, JingLong; He, Feng; Cao, Zexian

    2011-05-01

    Interplay of discharge and gas flow in the atmospheric pressure plasma jets generated with three different discharge modes [N. Jiang, A. L. Ji, and Z. X. Cao, J. Appl. Phys. 106, 013308 (2009); N. Jiang, A. L. Ji, and Z. X. Cao, J. Appl. Phys. 108, 033302 (2010)] has been investigated by simultaneous photographing of both plasma plumes and gas flows in the ambient, with the former being visualized by using an optical schlieren system. Gas flow gains a forward momentum from discharge except for the case of overflow jets at smaller applied voltages. Larger applied voltage implies an elongated plasma jet only for single-electrode mode; for dielectric barrier discharge jet the plume length maximizes at a properly applied voltage. These findings can help understand the underlying processes, and are useful particularly for the economic operation of tiny helium plasma jets and jet arrays.

  5. Characterization of a copper spark discharge plasma in argon atmosphere used for nanoparticle generation

    Science.gov (United States)

    Kohut, Attila; Galbács, Gábor; Márton, Zsuzsanna; Geretovszky, Zsolt

    2017-04-01

    Spark discharge nanoparticle generation is a dynamically developing application of discharge plasmas. In the present study a spark plasma used for nanoparticle generation is characterized by means of spatially and temporally resolved optical emission spectroscopy (OES) supplemented by fast imaging. The data acquired during the generation of copper nanoparticles in argon ambient is used to describe the spatial and temporal evolution of the species in the spark gap and to derive plasma parameters such as excitation temperature and electron concentration on one hand, and the concentration of the Cu species eroded by a single spark on the other. It is shown that temporally and spatially resolved OES together with a simple equilibrium model are efficient tools to estimate the characteristics of the spark discharge plasma that typically exists in spark discharge nanoparticle generators.

  6. Simulation Tool for Dielectric Barrier Discharge Plasma Actuators at Atmospheric and Sub-Atmospheric Pressures Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Traditional approaches for active flow separation control using dielectric barrier discharge (DBD) plasma actuators are limited to relatively low-speed flows and...

  7. Simulation Tool for Dielectric Barrier Discharge Plasma Actuators at Atmospheric and Sub-Atmospheric Pressures Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Traditional approaches for active flow separation control using dielectric barrier discharge (DBD) plasma actuators are limited to relatively low-speed flows and...

  8. Study of an Atmospheric Pressure Plasma Jet of Argon Generated by Column Dielectric Barrier Discharge

    Science.gov (United States)

    Nur, M.; Kinandana, A. W.; Winarto, P.; Muhlisin, Z.; Nasrudin

    2016-11-01

    An atmospheric of argon plasma jet was generated by using column dielectric barrier discharge has been investigated. In this study, argon gas was passed through the capillary column by regulating the flow rate of gas. This atmospheric pressure plasma jet (APPJ) was generated by a sinusoidal AC high voltage in the range of 0.4 kV to 10 kV and at frequencies of 15 kHz and 26 kHz. APPJ has been produced with flow rate of argon gas from 1 litter/min - 10 litters/min. The electric current has been taken with variation of voltage and each interval argon gas flow rate of 1 litter/min. The results show that electric current increase linearly and then it trends to saturation condition by the increasing of applied voltage. We found also that the length of the plasma jet increase by augmenting of applied voltage both for frequencies of 15 kHz and 26 kHz. Furthermore, our results show that length of plasma jet optimum for flow rate of argon gas of 2 litters/minute. In addition, we obtained that the larger applied voltage, the greater the temperature of the plasma jet.

  9. Activation of peroxydisulfate by gas-liquid pulsed discharge plasma to enhance the degradation of p-nitrophenol

    Science.gov (United States)

    Shang, Kefeng; Wang, Hao; Li, Jie; Lu, Na; Jiang, Nan; Wu, Yan

    2017-06-01

    Pulsed discharge in water and over water surfaces generates ultraviolet radiation, local high temperature, shock waves, and chemical reactive species, including hydroxyl radicals, hydrogen peroxide, and ozone. Pulsed discharge plasma (PDP) can oxidize and mineralize pollutants very efficiently, but high energy consumption restricts its application for industrial wastewater treatment. A novel method for improving the energy efficiency of wastewater treatment by PDP was proposed, in which peroxydisulfate (PDS) was added to wastewater and PDS was activated by PDP to produce more strong oxidizing radicals, including sulfate radicals and hydroxyl radicals, leading to a higher oxidation capacity for the PDP system. The experimental results show that the increase in solution conductivity slightly decreased the discharge power of the pulse discharge over the water surface. An increase in the discharge intensity improved the activation of PDS and therefore the degradation efficiency and energy efficiency of p-nitrophenol (PNP). An increase in the addition dosage of PDS greatly facilitated the degradation of PNP at a molar ratio of PDS to PNP of lower than 80:1, but the performance enhancement was no longer obvious at a dosage of more than 80:1. Under an applied voltage of 20 kV and a gas discharge gap of 2 mm, the degradation efficiency and energy efficiency of the PNP reached 90.7% and 45.0 mg kWh-1 for the plasma/PDS system, respectively, which was 34% and 18.0 mg kWh-1 higher than for the discharge plasma treatment alone. Analysis of the physical and chemical effects indicated that ozone and hydrogen peroxide were important for PNP degradation and UV irradiation and heat from the discharge plasma might be the main physical effects for the activation of PDS.

  10. Effect of Discharge Voltage on an Ion Sheath Formed at a Grid in a Multi-Dipole Discharge Plasma

    Institute of Scientific and Technical Information of China (English)

    M.K.Mishra; A.Phukan

    2008-01-01

    @@ It is experimentally demonstrated that a relatively strong ion-rich sheath formed at a fixed negative bias of the grid can be changed to arather weak ion sheath(sheath potential weakly retards dectrons)only by increasing the discharge voltage in the system.At sufficiently high negative grid bias,an increase of discharge voltage enhances the ion collection current at the grid.An explanation is put forward in support of this experimental observation.A slight density enhancement with a fall in plasma electron temperature is also observed with the increasing negative grid bias.

  11. Experiments of discharge guiding using strongly and weakly ionized plasma channels for laser-triggered lightning

    Science.gov (United States)

    Shimada, Yoshinori; Uchida, Shigeaki; Yamanaka, Chiyoe; Ogata, Akihisa; Yamanaka, Tatsuhiko; Kawasaki, Zen-ichiro; Fujiwara, Etsuo; Ishikubo, Yuji; Kawabata, Kinya

    2000-01-01

    Generation of a long laser-plasma channel capable of triggering and guiding an electrical discharge is a crucial issue for laser-triggering protection system. We make a long plasma channel to increase the probability of triggered lightning by laser. To produce a long laser plasma channel, we propose da new technique called hybrid plasma channel method which combines weakly and strongly ionized plasma channels to maximize laser-energy efficiency of discharge guiding. We investigate the characteristics of the hybrid plasma channels to maximize laser-energy efficiency of discharge guiding. We investigate the characteristics of the hybrid plasma channel method through several laboratory experiments. The weakly ionized channel was generated by UV laser pulses in air. As the number density of electrons in weakly ionized channel is proportional to 1.1 power of laser intensity, nitrogen and oxygen molecules can not attributed to the source of ionized plasma. It is suggested that dissociation process of impurities in air whose density is 1011 - 1012 cm-3 plays an important role in plasma formation and leader triggering effect. The 50 percent flashover voltage using the hybrid plasma channel method is lower than that without the weakly ionized plasma channel. It was also found that higher repetition rate of the plasma generation on lowers the V50 furthermore.

  12. Fluid model for a partially packed dielectric barrier discharge plasma reactor

    Science.gov (United States)

    Gadkari, Siddharth; Tu, Xin; Gu, Sai

    2017-09-01

    In this work, a two-dimensional numerical fluid model is developed for a partially packed dielectric barrier discharge (DBD) in pure helium. Influence of packing on the discharge characteristics is studied by comparing the results of DBD with partial packing with those obtained for DBD with no packing. In the axial partial packing configuration studied in this work, the electric field strength was shown to be enhanced at the top surface of the spherical packing material and at the contact points between the packing and the dielectric layer. For each value of applied potential, DBD with partial packing showed an increase in the number of pulses in the current profile in the positive half cycle of the applied voltage, as compared to DBD with no packing. Addition of partial packing to the plasma-alone DBD also led to an increase in the electron and ion number densities at the moment of breakdown. The time averaged electron energy profiles showed that a much higher range of electron energy can be achieved with the use of partial packing as compared to no packing in a DBD, at the same applied power. The spatially and time averaged values over one voltage cycle also showed an increase in power density and electron energy on inclusion of partial packing in the DBD. For the applied voltage parameters studied in this work, the discharge was found to be consistently homogeneous and showed the characteristics of atmospheric pressure glow discharge.

  13. Decontamination effects of low-temperature plasma generated by corona discharge. Part II: new insights.

    Science.gov (United States)

    Scholtz, V; Julák, J; Kríha, V; Mosinger, J; Kopecká, S

    2007-01-01

    The second part of our paper presents the results of experiments with the decontamination of surfaces by low-temperature plasma generated by corona discharge in air at atmospheric pressure. A simple device is described and the effects of the corona discharge on model microorganisms, viz. the yeast Candida albicans, Gram-negative bacteria Escherichia coli, Enterobacter aerogenes, Neisseria sicca, Stenotrophomonas maltophilia, Gram-positive bacteria Deinococcus radiodurans, Enterococcus faecium, Staphylococcus epidermidis, Streptococcus sanguinis, and vegetative and spore forms of Geobacillus stearothermophilus are discussed. A similar microbicidal effect after about one-minute exposure was observed in all vegetative forms of the microorganisms. Measurement in growth inhibition zones on a semisolid medium was used to determine the dependence of the microbicidal effect on exposure time and the distance between electrodes. Counting of colonies served to assess the microbicidal effect of the discharge on contaminated inert surfaces observable after more than 1 min exposure. Geobacillus stearothermophilus spores were found to have several times lower susceptibility to the action of the discharge and the microbicidal effect was observed only after an 8 min exposure. Reaction with the iodide reagent did not unambiguously demonstrate the difference between ozone and singlet oxygen as presumed active components of the corona. The area distribution of reactive oxygen species was determined; it was found to differ from the Wartburg law depending on exposure time. Qualitative evidence was obtained on the penetration of the reactive oxygen species into the semisolid medium.

  14. Steam Reforming of Dimethyl Ether by Gliding Arc Gas Discharge Plasma for Hydrogen Production

    Institute of Scientific and Technical Information of China (English)

    王保伟; 孙启梅; 吕一军; 杨美琳; 闫文娟

    2014-01-01

    Gliding arc gas discharge plasma was used for the generation of hydrogen from steam reforming of di-methyl ether (DME). A systemic procedure was employed to determine the suitable experimental conditions. It was found that DME conversion first increased up to the maximum and then decreased slightly with the increase of added water and air. The increase of total feed gas flow rate resulted in the decrease of DME conversion and hy-drogen yield, but hydrogen energy consumption dropped down to the lowest as total feed gas flow rate increased to 76 ml·min-1. Larger electrode gap and higher discharge voltage were advantageous. Electrode shape had an impor-tant effect on the conversion of DME and production of H2. Among the five electrodes, electrode 2# with valid length of 55 mm and the radian of 34 degrees of the top electrode section was the best option, which enhanced ob-viously the conversion of DME.

  15. Removal of NO and SO2 in Corona Discharge Plasma Reactor with Water Film

    Institute of Scientific and Technical Information of China (English)

    贺元吉; 董丽敏; 杨嘉祥

    2004-01-01

    In this paper, a novel type of a corona discharge plasma reactor was designed, which consists of needle-plate-combined electrodes, in which a series of needle electrodes are placed in a glass container filled with flue gas, and a plate electrode is immersed in the water. Based on this model, the removal of NO and SO2 was tested experimentally. In addition, the effect of streamer polarity on the reduction of SO2 and NO was investigated in detail. The experimental results show that the corona wind formed between the high-voltage needle electrode and the water by corona discharge enhances the cleaning efficiency of the flue gas because of the presence of water,and the cleaning efficiency will increase with the increase of applied dc voltage within a definite range. The removal efficiency of SO2 up to 98%, and about 85% of NOx removal under suitable conditions is obtained in our experiments.

  16. Wall ablation of heated compound-materials into non-equilibrium discharge plasmas

    Science.gov (United States)

    Wang, Weizong; Kong, Linghan; Geng, Jinyue; Wei, Fuzhi; Xia, Guangqing

    2017-02-01

    The discharge properties of the plasma bulk flow near the surface of heated compound-materials strongly affects the kinetic layer parameters modeled and manifested in the Knudsen layer. This paper extends the widely used two-layer kinetic ablation model to the ablation controlled non-equilibrium discharge due to the fact that the local thermodynamic equilibrium (LTE) approximation is often violated as a result of the interaction between the plasma and solid walls. Modifications to the governing set of equations, to account for this effect, are derived and presented by assuming that the temperature of the electrons deviates from that of the heavy particles. The ablation characteristics of one typical material, polytetrafluoroethylene (PTFE) are calculated with this improved model. The internal degrees of freedom as well as the average particle mass and specific heat ratio of the polyatomic vapor, which strongly depends on the temperature, pressure and plasma non-equilibrium degree and plays a crucial role in the accurate determination of the ablation behavior by this model, are also taken into account. Our assessment showed the significance of including such modifications related to the non-equilibrium effect in the study of vaporization of heated compound materials in ablation controlled arcs. Additionally, a two-temperature magneto-hydrodynamic (MHD) model accounting for the thermal non-equilibrium occurring near the wall surface is developed and applied into an ablation-dominated discharge for an electro-thermal chemical launch device. Special attention is paid to the interaction between the non-equilibrium plasma and the solid propellant surface. Both the mass exchange process caused by the wall ablation and plasma species deposition as well as the associated momentum and energy exchange processes are taken into account. A detailed comparison of the results of the non-equilibrium model with those of an equilibrium model is presented. The non-equilibrium results

  17. Observation of Quartz Cathode-Luminescence in a Low Pressure Plasma Discharge

    Science.gov (United States)

    Foster, John E.

    2004-01-01

    Intense, steady-state cathode-luminescence has been observed from exposure of quartz powder to a low pressure rf-excited argon plasma discharge. The emission spectra (400 to 850 nm) associated with the powder luminescence were documented as a function of bias voltage using a spectrometer. The emission was broad-band, essentially washing out the line spectra features of the argon plasma discharge.

  18. Parameters of the plasma of a dc pulsating discharge in a supersonic air flow

    Energy Technology Data Exchange (ETDEWEB)

    Shibkov, V. M., E-mail: shibkov@phys.msu.ru; Shibkova, L. V.; Logunov, A. A. [Moscow State University, Faculty of Physics (Russian Federation)

    2017-03-15

    A dc discharge in a cold (T = 200 K) supersonic air flow at a static pressure of 200–400 Torr was studied experimentally. The excited unsteady pulsating discharge has the form of a thin plasma channel with a diameter of ≤1 mm, stretched downstream the flow. Depending on the discharge current, the pulsation frequency varies from 800 to 1600 Hz and the electron temperature varies from 8000 to 15000 K.

  19. A Review on Chemical Effects in Aqueous Solution induced by Plasma with Glow Discharge

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Chemical effects in different aqueous solutions induced by plasma with glow dis charge electrolysis (GDE) and contact glow discharge electrolysis (CGDE) are described in this paper. The experimental and discharge characteristics are also reviewed. These are followed by a discussion of their mechanisms of both anodic and cathodic CGDE..

  20. Kinetic temperature of dust particle motion in gas-discharge plasma

    NARCIS (Netherlands)

    Norman, G. E.; Timofeev, A. V.

    2011-01-01

    A system of equations describing motion of dust particles in gas discharge plasma is formulated. This system is developed for a monolayer of dust particles with an account of dust particle charge fluctuations and features of the discharge near-electrode layer. Molecular dynamics simulation of the du

  1. Role of on-board discharge in shock wave drag reduction and plasma cloaking

    Institute of Scientific and Technical Information of China (English)

    Qiu Xiao-Ming; Tang De-Li; Sun Ai-Ping; Liu Wan-Dong; Zeng Xue-Jun

    2007-01-01

    In the present paper, a physical model is proposed for reducing the problem of the drag reduction of an attached bow shock around the nose of a high-speed vehicle with on-board discharge, to the problem of a balance between the magnetic pressure and gas pressure of plane shock of a partially ionized gas consisting of the environmental gas around the nose of the vehicle and the on-board discharge-produced plasma. The relation between the shock strength and the discharge-induced magnetic pressure is studied by means of a set of one-fluid, hydromagnetic equations reformed for the present purpose, where the discharge-induced magnetic field consists of the electron current (produced by the discharge)-induced magnetic field and the partially ionized gas flow-induced one. A formula for the relation between the above parameters is derived. It shows that the discharge-induced magnetic pressure can minimize the shock strength,successfully explaining the two recent experimental observations on attached bow shock mitigation and elimination in a supersonic flow during on-board discharge [Phys. Plasmas 9 (2002) 721 and Phys. Plasmas 7 (2000) 1345]. In addition,the formula implies that the shock elimination leaves room for a layer of higher-density plasma rampart moving around the nose of the vehicle, being favourable to the plasma radar cloaking of the vehicle. The reason for it is expounded.

  2. Field demonstration and commercialization of silent discharge plasma hazardous air pollutant control technology

    Energy Technology Data Exchange (ETDEWEB)

    Rosocha, L.A.; Coogan, J.J.; Korzekwa, R.A.; Secker, D.A. [Los Alamos National Lab., NM (United States); Reimers, R.F.; Herrmann, P.G.; Chase, P.J.; Gross, M.P. [High Mesa Technologies LLC, Santa Fe, NM (United States)]|[High Mesa Technologies LLC, Irvine, CA (United States); Jones, M.R. [Electric Power Research Inst., Palo Alto, CA (United States)

    1996-07-01

    Silent electrical discharge plasma (dielectric barrier) reactors can decompose gas-phase pollutants by free-radical attack or electron-induced fragmentation. The radicals or electrons are produced by the large average volume nonthermal plasmas generated in the reactor. In the past decade, the barrier configuration has attracted attention for destroying toxic chemical agents for the military, removing harmful greenhouse gases, and treating other environmentally- hazardous chemical compounds. At the Los Alamos National Laboratory, we have been studying the silent discharge plasma (SDP) for processing gaseous-based hazardous chemicals for approximately five years. The key objective is to convert hazardous or toxic chemicals into non-hazardous compounds or into materials which are more easily managed. The main applications have been for treating off-gases from thermal treatment units, and for abating hazardous air-pollutant emissions (e.g., industrial air emissions, vapors extracted from contaminated soil or groundwater). In this paper, we will summarize the basic principles of SDP processing, discuss illustrative applications of the technology, and present results from small-scale field tests that are relevant to our commercialization effort.

  3. Baking and helium glow discharge cleaning of SST-1 Tokamak with graphite plasma facing components

    Science.gov (United States)

    Semwal, P.; Khan, Z.; Raval, D. C.; Dhanani, K. R.; George, S.; Paravastu, Y.; Prakash, A.; Thankey, P.; Ramesh, G.; Khan, M. S.; Saikia, P.; Pradhan, S.

    2017-04-01

    Graphite plasma facing components (PFCs) were installed inside the SST-1 vacuum vessel. Prior to installation, all the graphite tiles were baked at 1000 °C in a vacuum furnace operated below 1.0 × 10-5 mbar. However due to the porous structure of graphite, they absorb a significant amount of water vapour from air during the installation process. Rapid desorption of this water vapour requires high temperature bake-out of the PFCs at ≥ 250 °C. In SST-1 the PFCs were baked at 250 °C using hot nitrogen gas facility to remove the absorbed water vapour. Also device with large graphite surface area has the disadvantage that a large quantity of hydrogen gets trapped inside it during plasma discharges which makes density control difficult. Helium glow discharge cleaning (He-GDC) effectively removes this stored hydrogen as well as other impurities like oxygen and hydrocarbon within few nano-meters from the surface by particle induced desorption. Before plasma operation in SST-1 tokamak, both baking of PFCs and He-GDC were carried out so that these impurities were removed effectively. The mean desorption yield of hydrogen was found to be 0.24. In this paper the results of baking and He-GDC experiments of SST-1 will be presented in detail.

  4. Spectroscopic studies of plasma in a carbon arc discharge for synthesis of nanomaterials

    Science.gov (United States)

    Vekselman, Vladislav; Feurer, Matthew; Yeh, Yao-Wen; Stratton, Brentley; Raitses, Yevgeny; LaboratoryPlasma Nanosynthesis Team

    2016-09-01

    An atmospheric pressure arc discharge with graphite electrodes is commonly used for synthesis of carbon nanomaterials such as buckyballs, nanotubes and graphene. In operation, the graphite anode ablates providing a feedstock material for synthesis these carbon nanostructures. Existing models predict that nucleation and growth of these nanomaterials in an arc discharge are governed by spatial distributions of density and temperature of plasma species. Control of these distributions can potentially enable optimization of nanosynthesis processes, to achieve the best combination of synthesis selectivity at the synthesis yield. In this work, we report first detail measurements of spatial distribution of arc plasma parameters obtained with a set of in-situ diagnostics, including optical emission spectroscopy and fast framing imaging. These parameters were measured in low- and high- anode ablation modes. Results of these measurements demonstrate a strong correlation between arc plasma and synthesis processes. This work was supported by U.S. Department of Energy, Office of Science, Basic Sciences, Materials Sciences and Engineering Division.

  5. Evaluation of pulsed corona discharge plasma for the treatment of petroleum-contaminated soil.

    Science.gov (United States)

    Li, Rui; Liu, Yanan; Mu, Ruiwen; Cheng, Wenyan; Ognier, Stéphanie

    2017-01-01

    Petroleum hydrocarbons released to the environment caused by leakage or illegal dumping pose a threat to human health and the natural environment. In this study, the potential of a pulsed corona discharge plasma system for treating petroleum-polluted soils was evaluated. This system removed 76.93 % of the petroleum from the soil in 60 min with an energy efficiency of 0.20 mg/kJ. Furthermore, the energy and degradation efficiencies for the remediation of soil contaminated by single polyaromatic hydrocarbons, such as phenanthrene and pyrene, were also compared, and the results showed that this technology had potential in organic-polluted soil remediation. In addition, the role of water molecules was investigated for their direct involvement in the formation and transportation of active species. The increase of soil moisture to a certain extent clearly benefitted degradation efficiency. Then, treated soils were analyzed by FTIR and GC-MS for proposing the degradation mechanism of petroleum. During the plasma discharging processes, the change of functional group and the detection of small aromatic hydrocarbons indicated that the plasma active species attached petroleum hydrocarbons and degradation occurred. This technique reported herein demonstrated significant potential for the remediation of heavily petroleum-polluted soil, as well as for the treatment of organic-polluted soils.

  6. Sporicidal properties from surface micro-discharge plasma under different plasma conditions at different humidities

    Science.gov (United States)

    Jeon, J.; Klaempfl, T. G.; Zimmermann, J. L.; Morfill, G. E.; Shimizu, T.

    2014-10-01

    In the current study, bacterial endospores of Geobacillus stearothermophilus are exposed to the surface micro-discharge plasma for 5 min and the humidity and power consumption are varied. At the low humidity of 5.5 ± 0.5 g m-3, almost no sporicidal effect (<0.5 log) is observed. At the high humidity of 17.9 ± 0.6 g m-3, the spore reduction increases monotonically up to 3.5 log with increasing power consumption. At a humidity of 10.4 ± 0.6 g m-3, the spores are inactivated in a limited range of power consumption with a maximum reduction of ˜2.5 log. The survival curves show a single-slope decrease of the spores. The contribution of heat and UV to the sporicidal effect as well as the inactivation of spores by the short-lived species from the plasma are ruled out. The concentration of ozone, one indicator for the long-lived species, is measured and no correlation with the sporicidal effect is found. In conclusion, water-related reactive species, e.g. hydrogen peroxide, appear to be responsible for the sporicidal effect under the investigated conditions. Furthermore, condensation of water at high humidity enables the plasma-activated water containing both long-lived and short-lived reactive species to contribute to the sporicidal effect.

  7. Synthesis of carbon nanotube array using corona discharge plasma-enhanced chemical vapor deposition

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A corona discharge plasma-enhanced chemical vapor deposition with the features of atmospheric pressure and low temperature has been developed to synthesize the carbon nanotube array. The array was synthesized from methane and hydrogen mixture in anodic aluminum oxide template channels in that cobalt was electrodeposited at the bottom. The characterization results by the scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy and Raman spectroscopy indicate that the array consists of carbon nanotubes with the diameter of about 40 nm and the length of more than 4 -m, and the carbon nanotubes are mainly restrained within the channels of templates.

  8. Studies on fluid model for numerical simulation of gas discharges in color plasma displays

    Institute of Scientific and Technical Information of China (English)

    HE Feng; LIU Chun-Liang

    2005-01-01

    The fluid models of gas discharge in alternating current plasma display panel (AC PDP) cell are discussed.From the Boltzmann equation, the hydrodynamic equations are derived, but this model consumes much computa tional time for simulation. The drift-diffusion approximation model and the local field approximation model are ob tained to simplify the numerical computation, and the approximation conditions of these two models are discussed in detail. The drift-diffusion approximation model gives more satisfactory result for PDP simulation, and the expression of energy balance equation is given completely in this model.

  9. Ionized sputter deposition using an extremely high plasma density pulsed magnetron discharge

    Energy Technology Data Exchange (ETDEWEB)

    Macak, Karol [Department of Physics, Linkoeping University, SE-581 83 Linkoeping, (Sweden); Kouznetsov, Vladimir [Department of Physics, Linkoeping University, SE-581 83 Linkoeping, (Sweden); Schneider, Jochen [Department of Physics, Linkoeping University, SE-581 83 Linkoeping, (Sweden); Helmersson, Ulf [Department of Physics, Linkoeping University, SE-581 83 Linkoeping, (Sweden); Petrov, Ivan [Materials Science Department and Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801 (United States)

    2000-07-01

    Time resolved plasma probe measurements of a novel high power density pulsed plasma discharge are presented. Extreme peak power densities in the pulse (on the order of several kW cm{sup -2}) result in a very dense plasma with substrate ionic flux densities of up to 1 A cm{sup -2} at source-to-substrate distances of several cm and at a pressure of 0.13 Pa (1 mTorr). The pulse duration was {approx}100 {mu}s with a pulse repetition frequency of 50 Hz. The plasma consists of metallic and inert gas ions, as determined from time resolved Langmuir probe measurements and in situ optical emission spectroscopy data. It was found that the plasma composition at the beginning of the pulse was dominated by Ar ions. As time elapsed metal ions were detected and finally dominated the ion composition. The effect of the process parameters on the temporal development of the ionic fluxes is discussed. The ionized portion of the sputtered metal flux was found to have an average velocity of 2500 m s{sup -1} at 6 cm distance from the source, which conforms to the collisional cascade sputtering theory. The degree of ionization of the sputtered metal flux at a pressure of 0.13 Pa was found to be 40%{+-}20% by comparing the total flux of deposited atoms with the charge measured for the metal ions in the pulse. (c) 2000 American Vacuum Society.

  10. Investigations of Biofilm-Forming Bacterial Cells by Atomic Force Microscopy Prior to and Following Treatment from Gas Discharge Plasmas

    Science.gov (United States)

    Vandervoort, K. G.; Joaquin, J. C.; Kwan, C.; Bray, J. D.; Torrico, R.; Abramzon, N.; Brelles-Marino, G.

    2007-03-01

    We present investigations of biofilm-forming bacteria before and after treatment from gas discharge plasmas. Gas discharge plasmas represent a way to inactivate bacteria under conditions where conventional disinfection methods are often ineffective. These conditions involve bacteria in biofilm communities, where cooperative interactions between cells make organisms less susceptible to standard killing methods. Rhizobium gallicum and Chromobacterium violaceum were imaged before and after plasma treatment using an atomic force microscope (AFM). In addition, cell wall elasticity was studied by measuring force distance curves as the AFM tip was pressed into the cell surface. Results for cell surface morphology and micromechanical properties for plasma treatments lasting from 5 to 60 minutes were obtained and will be presented.

  11. A comparative study for the inactivation of multidrug resistance bacteria using dielectric barrier discharge and nano-second pulsed plasma.

    Science.gov (United States)

    Park, Ji Hoon; Kumar, Naresh; Park, Dae Hoon; Yusupov, Maksudbek; Neyts, Erik C; Verlackt, Christof C W; Bogaerts, Annemie; Kang, Min Ho; Uhm, Han Sup; Choi, Eun Ha; Attri, Pankaj

    2015-09-09

    Bacteria can be inactivated through various physical and chemical means, and these have always been the focus of extensive research. To further improve the methodology for these ends, two types of plasma systems were investigated: nano-second pulsed plasma (NPP) as liquid discharge plasma and an Argon gas-feeding dielectric barrier discharge (Ar-DBD) as a form of surface plasma. To understand the sterilizing action of these two different plasma sources, we performed experiments with Staphylococcus aureus (S. aureus) bacteria (wild type) and multidrug resistant bacteria (Penicillum-resistant, Methicillin-resistant and Gentamicin-resistant). We observed that both plasma sources can inactivate both the wild type and multidrug-resistant bacteria to a good extent. Moreover, we observed a change in the surface morphology, gene expression and β-lactamase activity. Furthermore, we used X-ray photoelectron spectroscopy to investigate the variation in functional groups (C-H/C-C, C-OH and C=O) of the peptidoglycan (PG) resulting from exposure to plasma species. To obtain atomic scale insight in the plasma-cell interactions and support our experimental observations, we have performed molecular dynamics simulations to study the effects of plasma species, such as OH, H2O2, O, O3, as well as O2 and H2O, on the dissociation/formation of above mentioned functional groups in PG.

  12. Effect of Electron Energy Distribution on the Hysteresis of Plasma Discharge: Theory, Experiment, and Modeling.

    Science.gov (United States)

    Lee, Hyo-Chang; Chung, Chin-Wook

    2015-10-20

    Hysteresis, which is the history dependence of physical systems, is one of the most important topics in physics. Interestingly, bi-stability of plasma with a huge hysteresis loop has been observed in inductive plasma discharges. Despite long plasma research, how this plasma hysteresis occurs remains an unresolved question in plasma physics. Here, we report theory, experiment, and modeling of the hysteresis. It was found experimentally and theoretically that evolution of the electron energy distribution (EED) makes a strong plasma hysteresis. In Ramsauer and non-Ramsauer gas experiments, it was revealed that the plasma hysteresis is observed only at high pressure Ramsauer gas where the EED deviates considerably from a Maxwellian shape. This hysteresis was presented in the plasma balance model where the EED is considered. Because electrons in plasmas are usually not in a thermal equilibrium, this EED-effect can be regarded as a universal phenomenon in plasma physics.

  13. Validation of numerical codes for the analysis of plasma discharges

    Energy Technology Data Exchange (ETDEWEB)

    Albanese, R. (Univ. di Salerno, Dipt. di Ingegneria Elettronica, Fisciano (Italy)); Bottura, L. (NET Team, Garching (Germany)); Chiocchio, S. (NET Team, Garching (Germany)); Coccorese, E. (Univ. di Reggio Calabria, Ist. di Ingegneria Elettronica (Italy)); Gernhardt, J. (Max Planck IPP, Garching (Germany)); Gruber, O. (Max Planck IPP, Garching (Germany)); Fresa, R. (Univ. di Salerno, Dipt. di Ingegneria Elettronica, Fisciano (Italy)); Martone, R. (Univ. di Salerno, Dipt. di Ingegneria Elettronica, Fisciano (Italy)); Portone, A. (NET Team, Garching (Germany)); Seidel, U. (Max Planck IPP, Garching (Germany))

    1994-01-01

    Electromagnetic aspects in the design of ITER-like reactors call for an extensive use of complex and advanced numerical codes. For this reason a strong attention has been paid within the NET-Team to the code development. In particular, through a cooperation with some Italian universities, during the last years a number of numerical procedures were developed and integrated. In order to assess the code reliability and to gain confidence on their predictions for next generation ITER-like reactors, the validation of the codes against experiments has to be considered as a strict requirement. Aim of this paper is to give a comprehensive presentation of this problem in the light of the results of a campaign of validation runs. The main outcome of this work is that the computational procedures, which have been developed for the NET project and then extensively used also for ITER studies, can be considered as experimentally validated in a sufficiently wide range of cases of interest. In particular, computed values are compared with experimental measurements made during some typical ASDEX-Upgrade discharges. From the electromagnetic point of view, many features of this machine are common to the ITER concept, so that the results of the validation can reasonably be extended to the ITER case. (orig.)

  14. Recent results from studies of electric discharges in the mesosphere

    DEFF Research Database (Denmark)

    Neubert, Torsten; Rycroft, M.; Farges, T.

    2008-01-01

    The paper reviews recent advances in studies of electric discharges in the stratosphere and mesosphere above thunderstorms, and their effects on the atmosphere. The primary focus is on the sprite discharge occurring in the mesosphere, which is the most commonly observed high altitude discharge by...

  15. Parallel 3-D numerical simulation of dielectric barrier discharge plasma actuators

    Science.gov (United States)

    Houba, Tomas

    Dielectric barrier discharge plasma actuators have shown promise in a range of applications including flow control, sterilization and ozone generation. Developing numerical models of plasma actuators is of great importance, because a high-fidelity parallel numerical model allows new design configurations to be tested rapidly. Additionally, it provides a better understanding of the plasma actuator physics which is useful for further innovation. The physics of plasma actuators is studied numerically. A loosely coupled approach is utilized for the coupling of the plasma to the neutral fluid. The state of the art in numerical plasma modeling is advanced by the development of a parallel, three-dimensional, first-principles model with detailed air chemistry. The model incorporates 7 charged species and 18 reactions, along with a solution of the electron energy equation. To the author's knowledge, a parallel three-dimensional model of a gas discharge with a detailed air chemistry model and the solution of electron energy is unique. Three representative geometries are studied using the gas discharge model. The discharge of gas between two parallel electrodes is used to validate the air chemistry model developed for the gas discharge code. The gas discharge model is then applied to the discharge produced by placing a dc powered wire and grounded plate electrodes in a channel. Finally, a three-dimensional simulation of gas discharge produced by electrodes placed inside a riblet is carried out. The body force calculated with the gas discharge model is loosely coupled with a fluid model to predict the induced flow inside the riblet.

  16. Current evolution and plasma density space distribution in the reflex discharge with ring cathodes

    Science.gov (United States)

    Samokhin, A. A.; Liziakin, G. D.; Gavrikov, A. V.; Usmanov, R. A.; Smirnov, V. P.

    2016-11-01

    In this paper the numerical model of direct current gas discharge in drift-diffusion approximation is considered. For two-component plasma the processes of the gas discharge development in the reflex geometry with ring cathodes at a helium pressure of 35 mTorr are studied. We investigate the influence of: (a) the boundary conditions on the dielectric, (b) the electron temperature and (c) the coefficient of the secondary ion-electron emission on the I-U curve of the discharge. In a magnetic field of 50 Gauss the impact of the discharge voltage U = 300-700 V on the evolutionary process of the discharge is examined. The effect of diffusion on maintaining steady state discharge is researched. The parameters of the existence of a high-current (tens of μA) and low voltage (tens of mA) discharge modes are defined.

  17. Rydberg gas theory of a glow discharge plasma: I. Application to the electrical behaviour of a fast flowing glow discharge plasma.

    Science.gov (United States)

    Mason, Rod S; Mitchell, David J; Dickinson, Paul M

    2010-04-21

    Current-voltage (I-V) curves have been measured, independent of the main discharge, for electricity passing through the steady state fast flowing 'afterglow' plasma of a low power dc glow discharge in Ar. Voltage profiles along the axial line of conduction have been mapped using fixed probes and potentiometry, and the mass spectra of cations emerging from the downstream sampling Cone, also acting as a probe anode, were recorded simultaneously. Floating double probe experiments were also carried out. The electrical behavior is consistent with the well established I-V characteristics of such discharges, but does not comply with classical plasma theory predictions. The plasma decays along the line of conduction, with a lifetime of approximately 1 ms, despite carrying a steady state current, and its potential is below that of the large surface area anode voltage; a situation which cannot exist in the presence of a conventional free ion-electron plasma, unless the electron temperature is super cold. Currents, large by comparison with the main discharge current, and independent of it, are induced to flow through the downstream plasma, from the Anode (acting as a cathode) to the anodic ion exit Cone, induced by electron impact ionisation at the anode, but without necessarily increasing the plasma density. It appears to be conducted by direct charge transfer between a part of the anode surface (acting as cathode to the auxiliary circuit) and the plasma, without secondary electron emission or heating, which suggests the direct involvement of Rydberg atom intermediates. The reaction energy defect (= the work function of the electrode surface) fits with the plasma potential threshold observed for the cathodic reaction to occur. A true free ion-electron plasma is readily detected by the observation of cations at the anode surface, when induced at the downstream anode, at high bias voltages, by the electron impact ionisation in the boundary region. In contrast to the classical

  18. Physics of Collisional Plasmas Introduction to High-Frequency Discharges

    CERN Document Server

    Moisan, Michel

    2012-01-01

    The Physics of Collisional Plasmas deals with the plasma physics of interest to laboratory research and industrial applications, such as lighting, fabrication of microelectronics, destruction of greenhouse gases. Its emphasis is on explaining the physical mechanisms, rather than the detailed mathematical description and theoretical analysis. At the introductory level, it is important to convey the characteristic physical phenomena of plasmas, before addressing the ultimate formalism of kinetic theory, with its microscopic, statistical mechanics approach. To this aim, this text translates the physical phenomena into more tractable equations, using the hydrodynamic model; this considers the plasma as a fluid, in which the macroscopic physical parameters are the statistical averages of the microscopic (individual) parameters. This book is an introduction to the physics of collisional plasmas, as opposed to plasmas in space. It is intended for graduate students in physics and engineering . The first chapter intr...

  19. Study of carbon dioxide gas treatment based on equations of kinetics in plasma discharge reactor

    Science.gov (United States)

    Abedi-Varaki, Mehdi

    2017-08-01

    Carbon dioxide (CO2) as the primary greenhouse gas, is the main pollutant that is warming earth. CO2 is widely emitted through the cars, planes, power plants and other human activities that involve the burning of fossil fuels (coal, natural gas and oil). Thus, there is a need to develop some method to reduce CO2 emission. To this end, this study investigates the behavior of CO2 in dielectric barrier discharge (DBD) plasma reactor. The behavior of different species and their reaction rates are studied using a zero-dimensional model based on equations of kinetics inside plasma reactor. The results show that the plasma reactor has an effective reduction on the CO2 density inside the reactor. As a result of reduction in the temporal variations of reaction rate, the speed of chemical reactions for CO2 decreases and very low concentration of CO2 molecules inside the plasma reactor is generated. The obtained results are compared with the existing experimental and simulation findings in the literature.

  20. Degradation of Anionic Dye Eosin by Glow Discharge Electrolysis Plasma

    Institute of Scientific and Technical Information of China (English)

    GAO Jinzhang; MA Dongping; GUO Xiao; WANG Aixiang; FU Yan; WU Jianlin; YANG Wu

    2008-01-01

    This paper describes a novel method for the degradation of eosin by using glow discharge electrolysis (GDE). The effects of various parameters on the removal efficiency were studied. It was found that the eosin degradation could be raised considerably by increasing the applied voltage and the initial concentration, or by decreasing pH of the aqueous solution. Fe2+ ion had an evident accelerating effect on the eosin degradation. The degradation process of eosin obeyed a pseudo-first-order reaction. The relationship between the degradation rate constant κ and the reaction temperature T could be expressed by Arrhenius equation with which the apparent activation energy Ea of 14.110 kJ. Mol-1 and the pre-exponential factor k0 of 2.065×10-1 min-1 were obtained, too. The determination of hydroxyl radical was carried out by using N, N-dimethyl -p-nitrosoaniline (RNO) as a scavenger. The results showed that the hydroxyl radical plays an important role in the degradation process.

  1. Cylindrical dielectric barrier discharge plasma catalytic effect on chemical methods of silver nano-particle production

    Science.gov (United States)

    Bahrami, Zahra; Khani, Mohammad Reza; Shokri, Babak

    2016-11-01

    In this study, cylindrical dielectric barrier discharge plasma was used to study the catalytic effect on chemical methods of silver nano-particles for the first time. In this method, the processing time is short and the temperature of reaction is low. Also, the reactor is very simple, inexpensive, and accessible. In this work, pure AgNO3 as the precursor agent and poly vinyl pyrrolidone as the macromolecular surfactant were dissolved in ethanol as the solvent. UV-Vis and XRD were used to identify the colloidal and powder nano-particles, respectively. Optical emission spectroscopy was also used to identify the active species in plasma. Effects of gas flow rate, voltage, volume of solution, and processing time were also studied. Moreover, TEM and SEM images presented the mean diameter of nano-particle size around 10 to 20 nm. The results have been very promising.

  2. Anodization of aluminum and silicon in plasma of a non-self-sustained glow discharge

    Energy Technology Data Exchange (ETDEWEB)

    Burachevsky, Yu. A., E-mail: office@tusur.ru; Burdovitsin, V. A.; Oks, E. M. [Tomsk State University of Control Systems and Radioelectronics (Russian Federation)

    2011-12-15

    The results of anodization of aluminum and silicon in an oxygen plasma are presented. The plasma was generated by a non-self-sustained glow discharge with a hollow cathode excited by an electron beam at the oxygen pressure of 20 Pa. The density of the current flowing through the anodized specimen did not exceed 1.5 mA/cm{sup 2}, and its temperature was 200-250 Degree-Sign C. Continuous Al{sub 2}O{sub 3} and SiO{sub 2} films were formed on the aluminum and silicon surfaces. The growth rate of the oxide layers was 150-200 nm/h for Al{sub 2}O{sub 3} and 400-800 nm/h for SiO{sub 2}.

  3. Interplay between intrinsic plasma rotation and magnetic island evolution in disruptive discharges

    Science.gov (United States)

    Ronchi, G.; Severo, J. H. F.; Salzedas, F.; Galvão, R. M. O.; Sanada, E. K.

    2016-05-01

    The behavior of the intrinsic toroidal rotation of the plasma column during the growth and eventual saturation of m/ n = 2/1 magnetic islands, triggered by programmed density rise, has been carefully investigated in disruptive discharges in TCABR. The results show that, as the island starts to grow and rotate at a speed larger than that of the plasma column, the angular frequency of the intrinsic toroidal rotation increases and that of the island decreases, following the expectation of synchronization. As the island saturates at a large size, just before a major disruption, the angular speed of the intrinsic rotation decreases quite rapidly, even though the island keeps still rotating at a reduced speed. This decrease of the toroidal rotation is quite reproducible and can be considered as an indicative of disruption.

  4. Surface modification of polyvinyl alcohol/malonic acid nanofibers by gaseous dielectric barrier discharge plasma for glucose oxidase immobilization

    Energy Technology Data Exchange (ETDEWEB)

    Afshari, Esmail, E-mail: e.afshari@mail.sbu.ac.ir [Laser and Plasma Research Institute, Shahid Beheshti University, Evin, 1983963113 Tehran (Iran, Islamic Republic of); Mazinani, Saeedeh [Amirkabir Nanotechnology Research Institute (ANTRI), Amirkabir University of Technology, 15875-4413, Tehran (Iran, Islamic Republic of); Ranaei-Siadat, Seyed-Omid [Protein Research Center, Shahid Beheshti University, Evin, 1983963113 Tehran (Iran, Islamic Republic of); Ghomi, Hamid [Laser and Plasma Research Institute, Shahid Beheshti University, Evin, 1983963113 Tehran (Iran, Islamic Republic of)

    2016-11-01

    Highlights: • We fabricated polyvinyl alcohol/malonic acid nanofibers using electrospinning. • The surface nanofibers were modified by gaseous (air, nitrogen, CO{sub 2} and argon) dielectric barrier discharge. • Among them, air plasma had the most significant effect on glucose oxidase immobilization. • Chemical analysis showed that after modification of nanofibers by air plasma, the carboxyl group increased. • After air plasma treatment, reusability and storage stability of glucose oxidase immobilized on nanofibers improved. - Abstract: Polymeric nanofiber prepares a suitable situation for enzyme immobilization for variety of applications. In this research, we have fabricated polyvinyl alcohol (PVA)/malonic acid nanofibers using electrospinning. After fabrication of nanofibers, the effect of air, nitrogen, CO{sub 2}, and argon DBD (dielectric barrier discharge) plasmas on PVA/malonic acid nanofibers were analysed. Among them, air plasma had the most significant effect on glucose oxidase (GOx) immobilization. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectrum analysis and X-ray photoelectron spectroscopy (XPS) results revealed that in case of air plasma modified nanofibers, the carboxyl groups on the surface are increased. The scanning electron microscopy (SEM) images showed that, after GOx immobilization, the modified nanofibers with plasma has retained its nanofiber structure. Finally, we analysed reusability and storage stability of GOx immobilized on plasma modified and unmodified nanofibers. The results were more satisfactory for modified nanofibers with respect to unmodified ones.

  5. Dielectric Barrier Discharge (DBD) Plasma Actuators Thrust-Measurement Methodology Incorporating New Anti-Thrust Hypothesis

    Science.gov (United States)

    Ashpis, David E.; Laun, Matthew C.

    2014-01-01

    We discuss thrust measurements of Dielectric Barrier Discharge (DBD) plasma actuators devices used for aerodynamic active flow control. After a review of our experience with conventional thrust measurement and significant non-repeatability of the results, we devised a suspended actuator test setup, and now present a methodology of thrust measurements with decreased uncertainty. The methodology consists of frequency scans at constant voltages. The procedure consists of increasing the frequency in a step-wise fashion from several Hz to the maximum frequency of several kHz, followed by frequency decrease back down to the start frequency of several Hz. This sequence is performed first at the highest voltage of interest, then repeated at lower voltages. The data in the descending frequency direction is more consistent and selected for reporting. Sample results show strong dependence of thrust on humidity which also affects the consistency and fluctuations of the measurements. We also observed negative values of thrust or "anti-thrust", at low frequencies between 4 Hz and up to 64 Hz. The anti-thrust is proportional to the mean-squared voltage and is frequency independent. Departures from the parabolic anti-thrust curve are correlated with appearance of visible plasma discharges. We propose the anti-thrust hypothesis. It states that the measured thrust is a sum of plasma thrust and anti-thrust, and assumes that the anti-thrust exists at all frequencies and voltages. The anti-thrust depends on actuator geometry and materials and on the test installation. It enables the separation of the plasma thrust from the measured total thrust. This approach enables more meaningful comparisons between actuators at different installations and laboratories. The dependence on test installation was validated by surrounding the actuator with a large diameter, grounded, metal sleeve.

  6. Multiple solutions in the theory of direct current glow discharges: Effect of plasma chemistry and nonlocality, different plasma-producing gases, and 3D modelling

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, P. G. C.; Benilov, M. S. [Departamento de Física, CCCEE, Universidade da Madeira, Largo do Município, 9000 Funchal (Portugal)

    2013-10-15

    The work is aimed at advancing the multiple steady-state solutions that have been found recently in the theory of direct current (DC) glow discharges. It is shown that an account of detailed plasma chemistry and non-locality of electron transport and kinetic coefficients results in an increase of the number of multiple solutions but does not change their pattern. Multiple solutions are shown to exist for discharges in argon and helium provided that discharge pressure is high enough. This result indicates that self-organization in DC glow microdischarges can be observed not only in xenon, which has been the case until recently, but also in other plasma-producing gases; a conclusion that has been confirmed by recent experiments. Existence of secondary bifurcations can explain why patterns of spots grouped in concentric rings, observed in the experiment, possess in many cases higher number of spots in outer rings than in inner ones.

  7. Plasma characteristics of a high power helicon discharge

    Science.gov (United States)

    Ziemba, T.; Euripides, P.; Slough, J.; Winglee, R.; Giersch, L.; Carscadden, J.; Schnackenberg, T.; Isley, S.

    2006-08-01

    A new high power helicon (HPH) plasma system has been designed to provide input powers of several tens of kilowatts to produce a large area (0.5 m2) of uniform high-density, of at least 5 × 1017 m-3, plasma downstream from the helicon coil. Axial and radial plasma characteristics show that the plasma is to a lesser extent created in and near the helicon coil and then is accelerated into the axial and equatorial regions. The bulk acceleration of the plasma is believed to be due to a coupling of the bulk of the electrons to the helicon field, which in turn transfers energy to the ions via ambipolar diffusion. The plasma beta is near unity a few centimetres away from the HPH system and Bdot measurements show ΔB perturbations in the order of the vacuum magnetic field magnitude. In the equatorial region, a magnetic separatrix is seen to develop roughly at the mid-point between the helicon and chamber wall. The magnetic perturbation develops on the time scale of the plasma flow speed and upon the plasma reaching the chamber wall decays to the vacuum magnetic field configuration within 200 µs.

  8. Plasma characteristics of a high power helicon discharge

    Energy Technology Data Exchange (ETDEWEB)

    Ziemba, T; Euripides, P; Slough, J; Winglee, R; Giersch, L; Carscadden, J; Schnackenberg, T; Isley, S [Box 351310, University of Washington, Seattle WA, 98195 (United States)

    2006-08-01

    A new high power helicon (HPH) plasma system has been designed to provide input powers of several tens of kilowatts to produce a large area (0.5 m{sup 2}) of uniform high-density, of at least 5 x 10{sup 17} m{sup -3}, plasma downstream from the helicon coil. Axial and radial plasma characteristics show that the plasma is to a lesser extent created in and near the helicon coil and then is accelerated into the axial and equatorial regions. The bulk acceleration of the plasma is believed to be due to a coupling of the bulk of the electrons to the helicon field, which in turn transfers energy to the ions via ambipolar diffusion. The plasma beta is near unity a few centimetres away from the HPH system and Bdot measurements show {delta}B perturbations in the order of the vacuum magnetic field magnitude. In the equatorial region, a magnetic separatrix is seen to develop roughly at the mid-point between the helicon and chamber wall. The magnetic perturbation develops on the time scale of the plasma flow speed and upon the plasma reaching the chamber wall decays to the vacuum magnetic field configuration within 200 {mu}s.

  9. Study of the operational properties of the Capillary Plasma Electrode (CPE) discharges

    Science.gov (United States)

    Lopez, Jose; Jacome, David; Zhu, Wei-Dong; Figus, Margaret; Becker, Kurt H.

    2009-03-01

    Various approaches have been pursued to create stable atmospheric pressure discharges by extending the lifetime of the diffuse phase of the discharge to hundreds of microseconds. Previous research showed that the stability of the diffuse mode is dependent on the frequency (in the kHz range), gas type power, mode of the excitation, and geometrical confinement. Some of the most promising approaches are based on the recognition of the arc formation in high-pressure plasmas can be avoided and stable high-pressure plasma can be generated and maintained when the plasma are spatially constricted to the dimensions of tens to hundreds of microns. The Capillary Plasma Electrode (CPE) discharge is stable to produce stable atmospheric pressure nonequilibrium plasma. The CPE is similar in design to the Barrier Electrode Discharge, but has perforated dielectrics. The configuration, aside from exhibiting a diffuse mode of operation, also exhibits the so-called ``capillary jet'' mode, in which the capillaries “turn on” and a bright plasma jet emerges from the capillaries. The capillary jets from adjacent capillaries overlap so that the discharge appears uniform when the electrode contains an array of holes. There appears to be a threshold frequency for the capillary jet formation, which is strongly dependent on the L/D ratio of the capillaries, where D is diameter of the capillary and L its length. However, the operating principles and basic properties of this behavior are not well understood. The current work explores these modes of operations of the CPE by characterizing the electrical and optical emission properties of this discharge by examining a multi-hole discharge as well as a single capillary discharge reactor.

  10. Electron dynamics and plasma jet formation in a helium atmospheric pressure dielectric barrier discharge jet

    Energy Technology Data Exchange (ETDEWEB)

    Algwari, Q. Th. [Centre for Plasma Physics, School of Maths and Physics, Queen' s University Belfast, University Road, Belfast, Northern Ireland BT7 1NN (United Kingdom); Electronic Department, College of Electronics Engineering, Mosul University, Mosul 41002 (Iraq); O' Connell, D. [Centre for Plasma Physics, School of Maths and Physics, Queen' s University Belfast, University Road, Belfast, Northern Ireland BT7 1NN (United Kingdom); York Plasma Institute, Department of Physics, University of York, York YO10 5DD (United Kingdom)

    2011-09-19

    The excitation dynamics within the main plasma production region and the plasma jets of a kHz atmospheric pressure dielectric barrier discharge (DBD) jet operated in helium was investigated. Within the dielectric tube, the plasma ignites as a streamer-type discharge. Plasma jets are emitted from both the powered and grounded electrode end; their dynamics are compared and contrasted. Ignition of these jets are quite different; the jet emitted from the powered electrode is ignited with a slight time delay to plasma ignition inside the dielectric tube, while breakdown of the jet at the grounded electrode end is from charging of the dielectric and is therefore dependent on plasma production and transport within the dielectric tube. Present streamer theories can explain these dynamics.

  11. Separation Process of Polydisperse Particles in the Plasma of Radio-frequency Discharge

    Directory of Open Access Journals (Sweden)

    D.G. Batryshev

    2014-07-01

    Full Text Available Method of separation of polydisperse particles in the plasma of radio-frequency (RF discharge is considered. Investigation of plasma equipotential field gave conditions for separation. The purpose of this work was an obtaining of monodisperse particles in the plasma of RF discharge. Samples of monodisperse microparticles of silica and alumina were obtained. The size and chemical composition of samples were studied on a scanning electron microscope Quanta 3D 200i (SEM, USA FEI company. Average size of separated silica nanoparticles is 600 nm, silica and alumina microparticles is 5 mkm.

  12. Discharge characteristics of an ablative pulsed plasma thruster with non-volatile liquid propellant

    Science.gov (United States)

    Ling, William Yeong Liang; Schönherr, Tony; Koizumi, Hiroyuki

    2017-07-01

    Pulsed plasma thrusters (PPTs) are a form of electric spacecraft propulsion. They have an extremely simple structure and are highly suitable for nano/micro-spacecraft with weights in the kilogram range. Such small spacecraft have recently experienced increased growth but still lack suitable efficient propulsion systems. PPTs operate in a pulsed mode (one discharge = one shot) and typically use solid polytetrafluoroethylene (PTFE) as a propellant. However, new non-volatile liquids in the perfluoropolyether (PFPE) family have recently been found to be promising alternatives. A recent study presented results on the physical characteristics of PFPE vs. PTFE, showing that PFPE is superior in terms of physical characteristics such as its resistance to carbon deposition. This letter will examine the electrical discharge characteristics of PFPE vs. PTFE. The results demonstrate that PFPE has excellent shot-to-shot repeatability and a lower discharge resistance when compared with PTFE. Taken together with its physical characteristics, PFPE appears to be a strong contender to PTFE as a PPT propellant.

  13. An advanced time-dependent collisional-radiative model of helium plasma discharges

    Science.gov (United States)

    Claustre, J.; Boukandou-Mombo, C.; Margot, J.; Matte, J.-P.; Vidal, F.

    2017-10-01

    A new spatially averaged time-dependent collisional-radiative model for helium plasmas, coupled to the electron Boltzmann equation (EBE), has been developed. Its main novelties are: (1) full time dependence for both the multi-species kinetics and the EBE. It is shown that this is necessary to correctly simulate discharges where the parameters vary on nanoseconds-microsecond timescales. (2) All electron processes are accounted for accurately. In particular, for the various ionization and recombination processes, free electrons are added or removed at the appropriate energy, with the appropriate interpolation on the energy grid. (3) The energy dependence of the electron loss by ambipolar diffusion is taken into account approximately. (4) All of the processes which are known to be important in helium discharges for pressure P≤slant 760 Torr are included, and 42 energy levels up to n = 6, where n is the main quantum number, are taken into account. Atomic and molecular ions, as well as excimers, are also included. (5) The gas temperature is calculated self-consistently. The model is validated through comparisons with known numerical steady-state results of Santos et al (2014 J. Phys. D. 47 265201) which they compared to their experimental results, and good agreement is obtained for their measured quantities. It is then applied to post-discharge decay cases with very short power decay times. The time evolution of the population densities and reaction rates are analyzed in detail with emphasis on the observed large increase of the metastable density.

  14. Plasma chemistry in an atmospheric pressure Ar/NH3 dielectric barrier discharge

    DEFF Research Database (Denmark)

    Fateev, A.; Leipold, F.; Kusano, Y.

    2005-01-01

    An atmospheric pressure dielectric barrier discharge (DBD) in Ar/NH3 (0.1 - 10%) mixtures with a parallel plate electrode geometry was studied. The plasma was investigated by emission and absorption spectroscopy in the UV spectral range. Discharge current and voltage were measured as well. UV...... absorption spectroscopy was also employed for the detection of stable products in the exhaust gas. To clarify the different processes for ammonia decomposition, N-2(2 - 10%) was added to the plasma. Modeling of the chemical kinetics in an Ar/NH3 plasma was performed as well. The dominant stable products...... of an atmospheric pressure Ar/NH3 DBD are H-2, N-2 and N2H4. The hydrazine (N2H4) concentration in the plasma and in the exhaust gases at various ammonia concentrations and different discharge powers was measured. Thermal N2H4 decomposition into NH2 radicals may be used for NOx reduction processes....

  15. Long-Lived Vortex Structures in Collisional Pure and Gas-Discharge Nonneutral Electron Plasmas

    CERN Document Server

    Kervalishvili, N A

    2013-01-01

    The analysis of experimental investigations of equilibrium, interaction and dynamics of vortex structures in pure electron and gas-discharge electron nonneutral plasmas during the time much more than the electron-neutral collision time has been carried out. The problem of long confinement of the column of pure electron plasma in Penning-Malmberg trap is considered. The mechanism of stability of long-lived vortex structure in gas-discharge nonneutral electron plasma is investigated. The collapse of electron sheath in gas-discharge nonneutral electron plasma in Penning cell at high pressures of neutral gas is described. The interaction between the stable vortex structure and the annular electron sheath, and the action of vortex structures on the transport of electrons along and across the magnetic field are discussed.

  16. Treatment Characteristics of Polysaccharides and Endotoxin Using Oxygen Plasma Produced by RF Discharge

    Science.gov (United States)

    Kitazaki, Satoshi; Hayashi, Nobuya; Goto, Masaaki

    2010-10-01

    Treatment of polysaccharides and endotoxin were attempted using oxygen plasma produced by RF discharge. Oxygen radicals observed by optical light emission spectra are factors of decomposition of polysaccharides and endotoxin. Fourier transform infrared spectra indicate that most of chemical bonds in the polysaccharides are dissociated after irradiation of the oxygen plasma. Also, the decomposition rate of endotoxin was approximately 90% after irradiation of the oxygen plasma for 180 min.

  17. Oxygen functionalization of MWCNTs in RF-dielectric barrier discharge Ar/O2 plasma

    Science.gov (United States)

    Abdel-Fattah, E.; Ogawa, D.; Nakamura, K.

    2017-07-01

    The oxygenation of multi-wall carbon nanotubes (MWCNTs) was performed via a radio frequency dielectric barrier discharge (RF-DBD) in an Ar/{{\\text{H}}2}\\text{O} plasma mixture. The relative intensity of the Ar/{{\\text{O}}2} plasma species was characterized by optical emission spectroscopy (OES). The effects of treatment time, RF power and oxygen gas percentage on the chemical composition and surface morphology of MWCNTs were investigated by means of x-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and field emission scanning electron microscopy (FE-SEM). The results of FTIR and XPS revealed the presence of oxygen-containing functional groups on the MWCNTs treated in an Ar/{{\\text{O}}2} plasma at an RF power of 50 W and pressure of 400 Pa. The amount of oxygen functional groups (C=O, C-O, and O-COO) also increased by increasing treatment time up to 6 min, but slightly decreased when treatment time was increased by 10 min. The increase of oxygen gas percentage in the plasma mixture does not affect the oxygen content in the treated MWCNTs. Meanwhile, MWCNTs treated at high power (80 W) showed a reduction in oxygen functional groups in comparison with low RF power conditions. The Raman analysis was consistent with the XPS and FTIR results. The integrity of the nanotube patterns also remained damaged as observed by FE-SEM images. The MWCNTs treated in RF-DBD using the Ar/{{\\text{O}}2} plasma mixture showed improved dispersibility in deionized water. A correlation between the OES data and the observed surface characterization for an improved understanding of the functionalization of MWCNTs in Ar/{{\\text{O}}2} plasma was presented.

  18. Thermal behavior of bovine serum albumin after exposure to barrier discharge helium plasma jet

    Science.gov (United States)

    Jijie, R.; Pohoata, V.; Topala, I.

    2012-10-01

    Non-thermal plasma jets at atmospheric pressure are useful tools nowadays in plasma medicine. Various applications are tested such as cauterization, coagulation, wound healing, natural and artificial surfaces decontamination, and sterilization. In order to know more about the effects of gas plasma on biological supramolecules, we exposed protein powders to a barrier discharge helium plasma jet. Then, spectroscopic investigations were carried out in order to obtain information on protein secondary, tertiary, and quaternary structures. We obtained a reduction of the protein alpha-helix content after the plasma exposure and a different behavior, for both thermal denaturation/renaturation kinetics and thermal aggregation process.

  19. Effect of Electron Energy Distribution on the Hysteresis of Plasma Discharge: Theory, Experiment, and Modeling

    Science.gov (United States)

    Lee, Hyo-Chang; Chung, Chin-Wook

    2016-09-01

    Hysteresis, which is the history dependence of physical systems, indicates that there are more-than-two stable points in a given condition, and it has been considered to one of the most important topics in fundamental physics. Recently, the hysteresis of plasma has become a focus of research because stable plasma operation is very important for fusion reactors, bio-medical plasmas, and industrial plasmas for nano-device fabrication process. Interestingly, the bi-stability characteristics of plasma with a huge hysteresis loop have been observed in inductive discharge plasmas Because hysteresis study in such plasmas can provide a universal understanding of plasma physics, many researchers have attempted experimental and theoretical studies. Despite long plasma research, how this plasma hysteresis occurs remains an unresolved question in plasma physics. Here, we report theory, experiment, and modeling of the hysteresis. It was found experimentally and theoretically that evolution of the electron energy distribution (EED) makes a strong plasma hysteresis. In Ramsauer and non-Ramsauer gas experiments, it was revealed that the plasma hysteresis is observed only at high pressure Ramsauer gas where the EED deviates considerably from a Maxwellian shape. This hysteresis was presented in the plasma balance model where the EED is considered. Because electrons in plasmas are usually not in a thermal equilibrium, this EED-effect can be regarded as a universal phenomenon in plasma physics. This research was partially supported by Korea Research Institute of Standard and Science.

  20. High-power EUV lithography sources based on gas discharges and laser-produced plasmas

    Science.gov (United States)

    Stamm, Uwe; Ahmad, Imtiaz; Balogh, Istvan; Birner, H.; Bolshukhin, D.; Brudermann, J.; Enke, S.; Flohrer, Frank; G„bel, Kai; G÷tze, S.; Hergenhan, G.; Kleinschmidt, J.'rgen; Kl÷pfel, Diethard; Korobotchko, Vladimir; Ringling, Jens; Schriever, Guido; Tran, C. D.; Ziener, C.

    2003-06-01

    Semiconductor chip manufacturers are expecting to use extreme UV lithography for production in 2009. EUV tools require high power, brilliant light sources at 13.5 nm with collector optics producing 120 W average power at entrance of the illuminator system. Today the power and lifetime of the EUV light source are considered as the most critical issue for EUV lithography. The present paper gives an update of the development status of EUV light sources at XTREME technologies, a joint venture of Lambda Physik AG, Goettingen, and Jenoptik LOS GmbH, Jena, Germany. Results on both laser produced plasma (LPP) and gas discharge produced plasma (GDPP), the two major technologies in EUV sources, are given. The LPP EUV sources use xenon-jet target systems and pulsed lasers with 400 W average power at 10 kHz developed at XTREME technologies. The maximum conversion efficiency form laser power into EUV in-band power is 0.75% into 2π solid angle. With 300 W laser average power at 3300 Hz repetition rate up to 1.5 W EUV radiation is generated at 13.5 nm. After a collector of 5 sr this corresponds to 0.6 W in intermediate focus without spectral purity filter and 0.5 W in intermediate focus with spectral purity filter. The direct generation of the EUV emitting plasma from electrical discharges is much simpler than LPP because the electrical energy has not to be converted into laser radiation before plasma excitation. XTREME technologies' Xenon GDPP EUV sources use the Z-pinch principle with efficient sliding discharge pre-ionization. The plasma pinch size and the available emission angle have been matched to the etendue of the optical system of 2-3 mm2 sr, i.e. no additional etendue related loss reduces the usable EUV power from the source. In continuous operation at 1000 Hz the GDPP sources emit 50W into 2π solid angle are obtained from the Z-pinch sources. Spatial and temporal emission stability of the EUV sources is in the range of a few percent. Debris shields for EUV sources

  1. Time dependent atomic processes in discharge produced low Z plasma

    Science.gov (United States)

    Yuyama, M.; Sasaki, T.; Horioka, K.; Kawamura, T.

    2008-05-01

    The z-pinch simulation have been performed with magneto-hydro dynamics and atomic population kinetics codes. A factor associated with transient atomic processes was proposed. The atomic transient degrees of dopant lithium in hydrogen plasma were calculated with initial plasma densities of 1.0 × 1016 ~ 5.0 × 1017cm-3. The higher initial plasma density is, the lower is the transient degree generally. It is also found that the transient properties of the atomic processes are sensitive to ionization energy and electron temperature.

  2. Surface Modification of Asymmetric Polysulfone/Polyethylene Glycol Membranes by DC Ar-Glow Discharge Plasma

    Directory of Open Access Journals (Sweden)

    Chalad Yuenyao

    2016-01-01

    Full Text Available Polysulfone/polyethylene glycol (PSF/PEG membranes were prepared by dry/wet phase inversion method. Effects of direct current glow discharge plasma using argon as working gas on morphological structures and gas separation properties of membranes were studied. Alteration of membrane characteristics were analyzed by various techniques like contact angle, scanning electron microscope, Fourier transform infrared spectroscopy, and dynamic mechanical thermal analysis. Gas separation properties were measured in terms of permeation and ideal O2/N2 selectivity. Results showed that hydrophilic and gas separation properties of PSF/PEG membranes increased by plasma surface modification. It was also shown that the dosage of PEG and plasma treatment affected the morphological structures and mechanical and gas separation properties. The macro voids and transmembrane structure disappeared with a little amount of PEG dosage. Pore size and mechanical strength tend to decrease with increasing PEG dosage up to 10 wt%. Glass transition temperature (Tg receded from 201.8 to 143.7°C for pure PSF and PSF/PEG with PEG dosage of 10 wt%. O2 and N2 gases permeation through the 10-minute plasma treated membranes tend to increase. However, the permeation strongly dispersed when treatment time was more extended.

  3. Changes in Properties of Dielectric Barrier Discharge Plasma Jets for Different Gases and for Insulating and Conducting Transfer Plates

    Science.gov (United States)

    do Nascimento, Fellype; Moshkalev, Stanislav; Machida, Munemasa

    2017-03-01

    Dielectric barrier discharge (DBD) plasma jets have been studied extensively in recent years because of its wide range of applications. DBD plasmas can be produced using many different gases and can be applied to a broad variety of surfaces and substrates. This work provides comparisons of DBD plasmas generated using argon (Ar), helium (He), and nitrogen (N2), as well as their mixtures with water vapor in order to know how some plasma properties are affected by the use of different gases. All plasmas were studied in two different conditions: using a transfer plate made of a conductive material and using a transfer plate made of an insulating one. It was observed that the process of Penning ionization of nitrogen molecules by direct collisions with metastable atoms and molecules is evident and significant only in plasmas that use He as the working gas, which means that He atoms in metastable states have greater ability to transfer energy to molecules of nitrogen in the plasma. The collisions of metastable He with N2 molecules determine the vibrational temperature (T vib) values in He plasmas, while in Ar and N2 plasmas, the T vib values are determined mainly by collisions of electrons with N2 molecules. It was noticed that the use of an insulating or a conducting transfer plate as the sample holder affects the results of adhesion between poly(dimethylsiloxane) samples, and it is mainly due to the differences in the plasma power, with a higher plasma power leading to better adhesion.

  4. Preliminary Results Of A 600 Joules Small Plasma Focus Device

    Science.gov (United States)

    Lee, S. H.; Yap, S. L.; Wong, C. S.

    2009-07-01

    Preliminary results of a 600 J (3.7 μF, 18 kV) Mather type plasma focus device operated at low pressure will be presented. The discharge is formed between a solid anode with length of 6 cm and six symmetrically and coaxially arranged cathode rods of same lengths. The cathode base is profiled in a knife-edge design and a set of coaxial plasma gun are attached to it in order to initiate the breakdown and enhance the current sheath formation. The experiments have been performed in argon gas under a low pressure condition of several microbars. The discharge current and the voltage across the electrodes during the discharge are measured with high voltage probe and current coil. The current and voltage characteristics are used to determine the possible range of operating pressure that gives good focusing action. At a narrow pressure regime of 9.0±0.5 μbar, focusing action is observed with good reproducibility. Preliminary result of ion beam energy is presented. More work will be carried out to investigate the radiation output.

  5. Design of a plasma discharge circuit for particle wakefield acceleration

    CERN Document Server

    Anania, M P; Cianchi, A; Di Giovenale, D; Ferrario, M; Flora, F; Gallerano, G P; Ghigo, A; Marocchino, A; Massimo, F; Mostacci, A; Mezi, L; Musumeci, P; Serio, M; 10.1016/j.nima.2013.10.053

    2014-01-01

    Plasma wakefield acceleration is the most promising acceleration technique known nowadays, able to provide very high accelerating fields (10-100 GV m^-1), enabling acceleration of electrons to GeV energy in few centimetres. However, the quality of the electron bunches accelerated with this technique is still not comparable with that of conventional accelerators; radiofrequency-based accelerators, in fact, are limited in the accelerating field (10-100 MV m^-1) requiring therefore kilometric distances to reach the GeV energies, but can provide very bright electron bunches. Combining high brightness electron bunches from conventional accelerators and high accelerating fields reachable with plasmas could be a good compromise accelerators and high accelerating fields reachable with plasmas could be a good compromise allowing to further accelerate high brightness electron bunches coming from LINAC while preserving electron beam quality. Following the idea of plasma wave resonant excitation driven by a train of shor...

  6. Surface modification of polyvinyl alcohol/malonic acid nanofibers by gaseous dielectric barrier discharge plasma for glucose oxidase immobilization

    Science.gov (United States)

    Afshari, Esmail; Mazinani, Saeedeh; Ranaei-Siadat, Seyed-Omid; Ghomi, Hamid

    2016-11-01

    Polymeric nanofiber prepares a suitable situation for enzyme immobilization for variety of applications. In this research, we have fabricated polyvinyl alcohol (PVA)/malonic acid nanofibers using electrospinning. After fabrication of nanofibers, the effect of air, nitrogen, CO2, and argon DBD (dielectric barrier discharge) plasmas on PVA/malonic acid nanofibers were analysed. Among them, air plasma had the most significant effect on glucose oxidase (GOx) immobilization. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectrum analysis and X-ray photoelectron spectroscopy (XPS) results revealed that in case of air plasma modified nanofibers, the carboxyl groups on the surface are increased. The scanning electron microscopy (SEM) images showed that, after GOx immobilization, the modified nanofibers with plasma has retained its nanofiber structure. Finally, we analysed reusability and storage stability of GOx immobilized on plasma modified and unmodified nanofibers. The results were more satisfactory for modified nanofibers with respect to unmodified ones.

  7. Degradation of Acid Orange 7 Dye in Two Hybrid Plasma Discharge Reactors

    Institute of Scientific and Technical Information of China (English)

    SHEN Yongjun; LEI Lecheng; ZHANG Xingwang; DING Jiandong

    2014-01-01

    To get an optimized pulsed electrical plasma discharge reactor and to increase the energy utilization efficiency in the removal of pollutants,two hybrid plasma discharge reactors were designed and optimized.The reactors were compared via the discharge characteristics,energy transfer efficiency,the yields of the active species and the energy utilization in dye wastewater degradation.The results showed that under the same AC input power,the characteristics of the discharge waveform of the point-to-plate reactor were better.Under the same AC input power,the two reactors both had almost the same peak voltage of 22 kV.The peak current of the point-to-plate reactor was 146 A,while that of the wire-to-cylinder reactor was only 48.8 A.The peak powers of the point-to-plate reactor and the wire-to-cylinder reactor were 1.38 MW and 1.01 MW,respectively.The energy per pulse of the point-to-plate reactor was 0.2221 J,which was about 29.4% higher than that of the wire-to-cylinder reactor (0.1716 J).To remove 50% Acid Orange 7 (AO7),the energy utilizations of the point-to-plate reactor and the wireto-cylinder reactor were 1.02×10-9 mol/L and 0.61×10-9 mol/L,respectively.In the point-to-plate reactor,the concentration of hydrogen peroxide in pure water was 3.6 mmol/L after 40 min of discharge,which was higher than that of the wire-to-cylinder reactor (2.5 mmol/L).The concentration of liquid phase ozone in the point-to-plate reactor (5.7×10-2 mmol/L) was about 26.7% higher than that in the wire-to-cylinder reactor (4.5× 10-2 mmol/L).The analysis results of the variance showed that the type of reactor and reaction time had significant impacts on the yields of the hydrogen peroxide and ozone.The main degradation intermediates of AO7 identified by gas chromatography and mass spectrometry (GCMS) were acetic acid,maleic anhydride,pbenzoquinone,phenol,benzoic acid,phthalic anhydride,coumarin and 2-naphthol.Proposed degradation pathways were elucidated in light of the analyzed

  8. Glyphosate contaminated soil remediation by atmospheric pressure dielectric barrier discharge plasma and its residual toxicity evaluation.

    Science.gov (United States)

    Wang, Tiecheng; Ren, Jingyu; Qu, Guangzhou; Liang, Dongli; Hu, Shibin

    2016-12-15

    Glyphosate was one of the most widely used herbicides in the world. Remediation of glyphosate-contaminated soil was conducted using atmospheric pressure dielectric barrier discharge (DBD) plasma. The feasibility of glyphosate degradation in soil was explored, and the soil leachate toxicity after remediation was assessed via a seed germination test. The experimental results showed that approximately 93.9% of glyphosate was degraded within 45min of DBD plasma treatment with an energy yield of 0.47gkWh(-1), and the degradation process fitted the first-order kinetic model. Increasing the discharge voltage and decreasing the organic matter content of the soil were both found to facilitate glyphosate degradation. There existed appropriate soil moisture to realize high glyphosate degradation efficiency. Glyphosate mineralization was confirmed by changes of total organic carbon (TOC), chemical oxygen demand (COD), PO4(3-) and NO3(-). The degradation intermediates including glycine, aminomethylphosphonic acid, acetic acid, formic acid, PO4(3-) and NO3(-), CO2 and CO were observed. A possible pathway for glyphosate degradation in the soil using this system was proposed. Based on the soil leachate toxicity test using wheat seed germination, the soil did not exhibit any hazardous effects following high-efficiency glyphosate degradation.

  9. Plasma polymers deposited in atmospheric pressure dielectric barrier discharges: Influence of process parameters on film properties

    Energy Technology Data Exchange (ETDEWEB)

    Fricke, Katja, E-mail: k.fricke@inp-greifswald.de [Leibniz Institute for Plasma Science and Technology e.V. (INP Greifswald), Felix-Hausdorff-Str. 2, 17489 Greifswald (Germany); Girard-Lauriault, Pierre-Luc [Plasma Processing Laboratory, Department of Chemical Engineering, McGill University, 3610 rue University, Montreal, QC H3A 0C5 (Canada); Weltmann, Klaus-Dieter [Leibniz Institute for Plasma Science and Technology e.V. (INP Greifswald), Felix-Hausdorff-Str. 2, 17489 Greifswald (Germany); Wertheimer, Michael R. [Department of Engineering Physics, École Polytechnique de Montréal, Box 6079, Station Centre-Ville, Montreal, QC H3C 3A7 (Canada)

    2016-03-31

    We present results on the deposition of plasma polymer (PP) films in a dielectric barrier discharge system fed with mixtures of argon or nitrogen carrier gas plus different hydrocarbon precursors, where the latter possess different carbon-to-hydrogen ratios: CH{sub 4} < C{sub 2}H{sub 6} < C{sub 2}H{sub 4} = C{sub 3}H{sub 6} < C{sub 2}H{sub 2}. The influence of precursor gas mixture and flow rate, excitation frequency, and absorbed power on PP film compositions and properties has been investigated. The discharge was characterized by electrical measurements, while the chemical compositions and structures of coatings were analysed by X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, total combustion, and elastic recoil detection analyses, the latter two for determining carbon-to-hydrogen ratios. Scanning electron microscopy was used to study the coatings' morphology, and profilometry for evaluating deposition rates. - Highlights: • Atmospheric pressure DBD is used to deposit organic hydrocarbon films. • High deposition rates can be achieved by varying the power and/or gas mixture ratio. • Process parameters affect the films' surface chemical composition and morphology. • Deposited films are not soluble in aqueous environment. • No delamination of coatings produced from argon plasma.

  10. The magnetized dusty plasma discharge negative and positive space charge modes

    CERN Document Server

    Cramer, N F; Cramer, Neil F.; Vladimirov, Sergey

    2004-01-01

    The structure of a discharge across a magnetic field in a dusty plasma is analysed. The dust macroparticles are negatively charged, but are unmagnetized because of their high mass. The electrons are highly magnetized, and the ions have intermediate magnetization. This results in different transport rates of the different species across the magnetic field. Depending on the size of the magnetic field, and the relative charge on the different species, the dust grains can be the dominant current carrier. The space charge clouds near the electrodes will then be determined by the relative mobility of the different species. The discharge can operate in one of two modes, a positive space charge (PSC) mode, characterized by a strong cathode fall, and a negative space charge (NSC) mode, characterized by a broad anode fall. Features unique to the dust particles can also play a role in the structure of the discharge, such as the variable equilibrium charge on the grains, dependent on the local potential and species tempe...

  11. Anomalous kinetic energy of a system of dust particles in a gas discharge plasma

    Energy Technology Data Exchange (ETDEWEB)

    Norman, G. E., E-mail: norman@ihed.ras.ru; Stegailov, V. V., E-mail: stegailov@gmail.com; Timofeev, A. V., E-mail: timofeevalvl@gmail.com [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)

    2011-11-15

    The system of equations of motion of dust particles in a near-electrode layer of a gas discharge has been formulated taking into account fluctuations of the charge of a dust particle and the features of the nearelectrode layer of the discharge. The molecular dynamics simulation of the system of dust particles has been carried out. Performing a theoretical analysis of the simulation results, a mechanism of increasing the average kinetic energy of dust particles in the gas discharge plasma has been proposed. According to this mechanism, the heating of the vertical oscillations of dust particles is initiated by induced oscillations generated by fluctuations of the charge of dust particles, and the energy transfer from vertical to horizontal oscillations can be based on the parametric resonance phenomenon. The combination of the parametric and induced resonances makes it possible to explain an anomalously high kinetic energy of dust particles. The estimate of the frequency, amplitude, and kinetic energy of dust particles are close to the respective experimental values.

  12. Transferred plasma jet from a dielectric barrier discharge for processing of poly(dimethylsiloxane) surfaces

    CERN Document Server

    Nascimento, Fellype do; Canesqui, Mara A; Moshkalev, Stanislav

    2016-01-01

    In this work we studied processing of poly(dimethylsiloxane) (PDMS) surfaces using dielectric barrier discharge (DBD) plasma in two different assemblies, one using the primary plasma jet obtained from a conventional DBD and the other using a DBD plasma jet transfer. The evolution of water contact angle (WCA) in function of plasma processing time and in function of aging time as well as the changes in the surface roughness of PDMS samples for both plasma treatments have been studied. We also compared vibrational and rotational temperatures for both plasmas and for the first time the vibrational temperature (T_vib) for the transferred plasma jet has been shown to be higher as compared with the primary jet. The increment in the T_vib value seems to be the main reason for the improvements in adhesion properties and surface wettability for the transferred plasma jet. Possible explanations for the increase in the vibrational temperature are presented.

  13. Discharge conditions for CW and pulse-modulated surface-wave plasmas in low-temperature sterilization

    Energy Technology Data Exchange (ETDEWEB)

    Xu, L [Department of Electrical and Electronic Engineering, Faculty of Engineering, Shizuoka University, 3-5-1 Johoku, Hamamatsu 432-8561 (Japan); Terashita, F [Department of Electrical and Electronic Engineering, Faculty of Engineering, Shizuoka University, 3-5-1 Johoku, Hamamatsu 432-8561 (Japan); Nonaka, H [Department of Electrical and Electronic Engineering, Faculty of Engineering, Shizuoka University, 3-5-1 Johoku, Hamamatsu 432-8561 (Japan); Ogino, A [Department of Electrical and Electronic Engineering, Faculty of Engineering, Shizuoka University, 3-5-1 Johoku, Hamamatsu 432-8561 (Japan); Nagata, T [Department of Microbiology and Immunology, Hamamatsu University School of Medicine, 1-20-1 Handa-yama, Hamamatsu 431-3192 (Japan); Koide, Y [Department of Microbiology and Immunology, Hamamatsu University School of Medicine, 1-20-1 Handa-yama, Hamamatsu 431-3192 (Japan); Nanko, S [Nissin Inc., 10-7 Kamei-cho, Takarazuka 665-0047 (Japan); Kurawaki, I [GMA Co. Ltd., 3898-1, Asaba, Fukuroi, 437-1101 (Japan); Nagatsu, M [Department of Electrical and Electronic Engineering, Faculty of Engineering, Shizuoka University, 3-5-1 Johoku, Hamamatsu 432-8561 (Japan)

    2006-01-07

    The discharge conditions required for low-temperature plasma sterilization were investigated using low-pressure surface-wave plasma (SWP). The discharge conditions for both continuous wave (CW) and pulse-modulated SWPs in low-temperature sterilization of Geobacillus stearothermophilus with a population of 1.5 x 10{sup 6} and 3.0 x 10{sup 6} were studied by varying the microwave input power from 500 W to 3 kW, and the effective plasma treatment time from 40 to 300 s. Results showed that sterilization was possible in a shorter treatment time using a higher microwave power for both CW and pulse-modulated SWPs. Pulse-modulated SWPs gave effective sterilization at a temperature roughly 10 to 20 deg. C below that of CW SWPs under the same average microwave power.

  14. Discharge conditions for CW and pulse-modulated surface-wave plasmas in low-temperature sterilization

    Science.gov (United States)

    Xu, L.; Terashita, F.; Nonaka, H.; Ogino, A.; Nagata, T.; Koide, Y.; Nanko, S.; Kurawaki, I.; Nagatsu, M.

    2006-01-01

    The discharge conditions required for low-temperature plasma sterilization were investigated using low-pressure surface-wave plasma (SWP). The discharge conditions for both continuous wave (CW) and pulse-modulated SWPs in low-temperature sterilization of Geobacillus stearothermophilus with a population of 1.5 × 106 and 3.0 × 106 were studied by varying the microwave input power from 500 W to 3 kW, and the effective plasma treatment time from 40 to 300 s. Results showed that sterilization was possible in a shorter treatment time using a higher microwave power for both CW and pulse-modulated SWPs. Pulse-modulated SWPs gave effective sterilization at a temperature roughly 10 to 20 °C below that of CW SWPs under the same average microwave power.

  15. [Plasma temperature of white-eye hexagonal pattern in dielectric barrier discharge].

    Science.gov (United States)

    Zhao, Yang; Dong, Li-fang; Fu, Hong-yan

    2015-01-01

    content are used to estimate the variations of electron density of the spot, the ring, and the halo of the white-eye hexagonal pattern. In the same argon content condition, the molecule vibrational temperatures of halo, ring, and spot in the white-eye hexagonal pattern are in descending order, while the electron densities of halo, ring, and spot are in ascending order. With argon content increasing from 70% to 90%, both the molecule vibrational temperature and the electron density of the spot increase, while both of them of the halo decrease. And the molecule vibrational temperature of the ring keeps constant, while its electron density decreases. The experimental results indicate that the plasma state of the spot, the halo and the ring in a white-eye cell of the white-eye hexagonal pattern is different. These results are of great importance to the investigation of the multilayer structure of the patterns in dielectric barrier discharge and applications in industry.

  16. Study of the interrelation between the electrotechnical parameters of the plasma focus discharge circuit and the plasma compression dynamics on the PF-3 and PF-1000 facilities

    Energy Technology Data Exchange (ETDEWEB)

    Mitrofanov, K. N., E-mail: mitrkn@inbox.ru [Troitsk Institute for Innovation and Fusion Research (Russian Federation); Krauz, V. I., E-mail: krauz-vi@nrcki.ru, E-mail: vkrauz@yandex.ru [National Research Centre Kurchatov Institute (Russian Federation); Grabovski, E. V. [Troitsk Institute for Innovation and Fusion Research (Russian Federation); Myalton, V. V.; Vinogradov, V. P. [National Research Centre Kurchatov Institute (Russian Federation); Paduch, M. [Institute of Plasma Physics and Laser Microfusion (Poland); Scholz, M. [Polish Academy of Sciences, Niewodniczański Institute of Nuclear Physics (Poland); Karpiński, L. [Łukasiewicz University of Technology, Faculty of Electrical and Computer Engineering (Poland)

    2015-05-15

    The main stages of the plasma current sheath (PCS) dynamics on two plasma focus (PF) facilities with different geometries of the electrode system, PF-3 (Filippov type) and PF-1000 (Mather type), were studied by analyzing the results of the current and voltage measurements. Some dynamic characteristics, such as the PCS velocity in the acceleration phase in the Mather-type facility (PF-1000), the moment at which the PCS reaches the anode end, and the plasma velocity in the radial stage of plasma compression in the PF-3 Filippov-type facility, were determined from the time dependence of the inductance of the discharge circuit with a dynamic plasma load. The energy characteristics of the discharge circuit of the compressing PCS were studied for different working gases (deuterium, argon, and neon) at initial pressures of 1.5–3 Torr in discharges with energies of 0.3–0.6 MJ. In experiments with deuterium, correlation between the neutron yield and the electromagnetic energy deposited directly in the compressed PCS was investigated.

  17. Efficient new process for the desulfurization of mixtures of air and hydrogen sulfide via a dielectric barrier discharge plasma

    Directory of Open Access Journals (Sweden)

    S. Dahle

    2015-10-01

    Full Text Available The efficient removal of hydrogen sulfide, H2S, from streams of H2S in air via a dielectric barrier discharge (DBD plasma has been investigated using a quadrupole mass spectrometer. A suitable plasma device with a reservoir for storing sorbent powder of various kinds within the plasma region was constructed. Plasma treatments of gas streams with high concentrations of hydrogen sulfide in air yielded a removal of more than 98% of the initial hydrogen sulfide and a deposition of sulfur at the surface of the dielectric, while small amounts of sulfur dioxide were generated. The presence of calcium carbonate within the plasma region of the DBD device resulted in the removal of over 99% of the initial hydrogen sulfide content and the removal of 98% of the initial sulfur dioxide impurities from the gas mixture.

  18. Impact of low-pressure glow-discharge-pulsed plasma polymerization on properties of polyaniline thin films

    Science.gov (United States)

    Jatratkar, Aviraj A.; Yadav, Jyotiprakash B.; Deshmukh, R. R.; Barshilia, Harish C.; Puri, Vijaya; Puri, R. K.

    2016-12-01

    This study reports on polyaniline thin films deposited on a glass substrate using a low-pressure glow-discharge-pulsed plasma polymerization method. The polyaniline thin film obtained by pulsed plasma polymerization has been successfully demonstrated as an optical waveguide with a transmission loss of 3.93 dB cm-1, and has the potential to be employed in integrated optics. An attempt has been made to investigate the effect of plasma OFF-time on the structural, optical as well as surface properties of polyaniline thin film. The plasma ON-time has been kept constant and the plasma OFF-time has been varied throughout the work. The plasma OFF-time strongly influenced the properties of the polyaniline thin film, and a nanostructured and compact surface was revealed in the morphological studies. The plasma OFF-time was found to enhance film thickness, roughness, refractive index and optical transmission loss, whereas it reduced the optical band gap of the polyaniline thin films. Retention in the aromatic structure was confirmed by FTIR results. Optical studies revealed a π-π* electronic transition at about 317 nm as well as the formation of a branched structure. As compared with continuous wave plasma, pulsed plasma polymerization shows better properties. Pulsed plasma polymerization reduced the roughness of the film from 1.2 nm to 0.42 nm and the optical transmission loss from 6.56 dB cm-1 to 3.39 dB cm-1.

  19. Characterization of a dielectric barrier discharge in contact with liquid and producing a plasma activated water

    Science.gov (United States)

    Neretti, G.; Taglioli, M.; Colonna, G.; Borghi, C. A.

    2017-01-01

    In this work a low-temperature plasma source for the generation of plasma activated water (PAW) is developed and characterized. The plasma reactor was operated by means of an atmospheric-pressure air dielectric barrier discharge (DBD). The plasma generated is in contact with the water surface and is able to chemically activate the liquid medium. Electrodes were supplied by both sinusoidal and nanosecond-pulsed voltage waveforms. Treatment times were varied from 2 to 12 min to increase the energy dose released to the water by the DBD plasma. The physics of the discharge was studied by means of electrical, spectroscopic and imaging diagnostics. The interaction between the plasma and the liquid was investigated as well. Temperature and composition of the treated water were detected. Images of the discharges showed a filamentary behaviour in the sinusoidal case and a more homogeneous behaviour in the nanosecond-pulsed one. The images and the electrical measurements allowed to evaluate an average electron number density of about 4  ×  1019 and 6  ×  1017 m-3 for the sinusoidal and nanosecond-pulsed discharges respectively. Electron temperatures in the range of 2.1÷2.6 eV were measured by using spectroscopic diagnostics. Rotational temperatures in the range of 318-475 K were estimated by fitting synthetic spectra with the measured ones. Water temperature and pH level did not change significantly after the exposure to the DBD plasma. The production of ozone and hydrogen peroxide within the water was enhanced by increasing the plasma treatment time and the energy dose. Numerical simulations of the nanosecond-pulsed discharge were performed by using a self-consistent coupling of state-to-state kinetics of the air mixture with the Boltzmann equation of free electron kinetics. Temporal evolution of the electron energy distribution function shows departure from the Maxwellian distribution especially during the afterglow phase of the discharge. When

  20. High-pressure discharges with imposed stability resulting in reduced power requirements

    Science.gov (United States)

    Brooks, N. H.; Jensen, T. H.; Moeller, C. M.

    2003-08-01

    High-pressure plasma discharge columns that are long and straight, as well as uniform in the axial direction, have been generated in a steady state. These discharges, stabilized by rotation of the containment envelope about a horizontal axis, have reduced heat transport to the wall due to the absence of buoyancy-driven radial convection and the elimination of eddies caused by sheared flow. These "rotating tube discharges" may take the form of electric arcs powered with dc or low-frequency ac; or of electrodeless plasmas, heated by electromagnetic waves at rf or microwave frequencies.

  1. Reduction of TiO2 with hydrogen cold plasma in DC pulsed glow discharge

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yu-wen; DING Wei-zhong; LU Xiong-gang; GUO Shu-qiang; XU Kuang-di

    2005-01-01

    The reduction of TiO2 to Ti2O3 with hydrogen cold plasma generated by a DC pulsed glow discharge was realized under 2 500 Pa at 1 233 K. Only a little of Ti10O19 and Ti9O17 was detected for using molecular hydrogen.Enhancement effects of hydrogen cold plasma on the reduction were discussed in terms of thermodynamic coupling,kinetics and plasma sheath. The exited hydrogen species are considered more effective reducing agents. It is instructive to reduce refractory oxides with plasma hydrogen at the reduced temperature.

  2. Broadband and long lifetime plasma-antenna in air initiated by laser-guided discharge

    Science.gov (United States)

    Théberge, Francis; Gravel, Jean-François; Kieffer, Jean-Claude; Vidal, François; Châteauneuf, Marc

    2017-08-01

    In this work, we demonstrate the coupling and emission of radio-frequency (RF) signals from laser-guided discharge in ambient air. The produced 100-cm long plasma-antenna is broadband and can emit RF signals for more than 2 ms, which corresponds to an enhancement of the plasma-antenna lifetime of 4 orders of magnitude relative to previous demonstrations using laser-based plasma filamentation. The generation of large diameter plasma-antennas in the air allows to broadcast RF signals efficiently from ˜10 MHz to few tens of GHz.

  3. Unfiltered Diesel Engine Exhaust Treatment by Discharge Plasma:Effect of Soot Oxidation

    Institute of Scientific and Technical Information of China (English)

    B. S. Rajanikanth; Subhankar Das; A. D. Srinivasan

    2004-01-01

    A cascaded system of electrical discharges (Non-thermal plasma), catalyst and adsorption process was investigated for the removal of oxides of nitrogen (NO x) and carbon monoxide (CO) from a Diesel engine raw exhaust. The three processes were separately studied first, and then the cascaded processes, namely plasma-catalyst and plasma-adsorbent, were investigated. In this paper main emphasis was laid on the effect of carbonaceous soot oxidation on the plasma treatment process. While the cascaded plasma-catalyst process exhibits a higher CO removal, the cascaded plasma-adsorbent process exhibits a higher NO x removal. The experiments were conducted under no-load. The plasma and adsorbent reactors were kept at room temperature throughout the experiment while the catalyst reactor was kept at 200oC / 300oC.

  4. Plasma discharge and time-dependence of its effect to bacteria.

    Science.gov (United States)

    Justan, I; Cernohorska, L; Dvorak, Z; Slavicek, P

    2014-07-01

    Several types of plasma discharge have been proven to have a capacity for sterilization. Our goal is to introduce new nonthermal plasma pencil. We used it to sterilize different microbial populations with differing ages. We used a plasma discharge of the following characteristics: radio frequency barrier discharger at atmospheric pressure with a working frequency of 13.56 MHz, and the working gas used was argon. We performed 110 tests with the following microbial populations: Pseudomonas aeruginosa, Staphylococcus aureus, Proteus species, and Klebsiella pneumoniae. All populations were inoculated on the previous day and also on the day of our experiment. We made our evaluations the following day and also after 5 days, with all our microbial populations. Eradication of microbial populations is dependent on the plasma discharge exposure time in all cases. With regard to freshly inoculated microbes, we were able to sterilize agar with intensive exposure lasting for 10 s of colonies Pseudomonas, Proteus, and Klebsiella. The most resistant microbe seems to be S. aureus, which survives 5 s of coherent exposure in half of the cases. Using the lightest plasma discharge exposure, we achieved a maximum of 10(4)-10(5) CFU/mL (colony-forming unit - CFU). Regarding older microbial populations inoculated the day before the experiment, we can only decrease population growth to 10(5) CFU/mL approximately, but never completely sterilize. The plasma discharge with our characteristics could be used for the sterilization of the aforementioned superficially growing microbes, but does not sufficiently affect deeper layers and thus seems to be a limitation for eradication of the already erupted colonies.

  5. Nanosecond pulsed sliding dielectric barrier discharge plasma actuator for airflow control: Electrical, optical, and mechanical characteristics

    Science.gov (United States)

    Bayoda, K. D.; Benard, N.; Moreau, E.

    2015-08-01

    Plasma actuators used for active flow control are widely studied because they could replace mechanical actuators. Industrial applications of these plasma actuators sometimes require a large surface plasma sheet in view of increasing the interaction region between the discharge and the incoming flow. Instead of using a typical two-electrode nanosecond pulsed dielectric barrier discharge for which the interaction region is limited to about 20 mm, this study proposes to characterize a nanosecond sliding discharge based on a three-electrode geometry in order to increase the extension length up to the electrode gap. This sliding discharge is compared to the typical nanosecond dielectric barrier discharge by means of electrical, optical, and mechanical diagnostics. Electrical characterization reveals that the deposited energy can be widely increased. Time-resolved Intensified Charge Coupled Device (iCCD) images of the discharge development over the dielectric surface highlight that the intensity and the propagation velocity of streamers are strongly affected by the DC voltage applied at the third electrode. Finally, qualitative and quantitative characterizations of the pressure wave due to the surrounding gas heating are proposed by means of Schlieren visualizations and high frequency pressure measurements, respectively.

  6. Characterization of the Basic Operational Properties of the Capillary Plasma Electrode (CPE) Discharge

    Science.gov (United States)

    Lopez, Jose; Zhu, Weidong; Figus, Margaret; Becker, Kurt

    2008-10-01

    Various approaches have been pursued to create stable atmospheric pressure discharges by extending the lifetime of the diffuse phase of the discharge to hundreds of microseconds. Previous research showed that the stability of the diffuse mode is dependent on the frequency (in the kHz range), gas type, power, mode of the excitation, and geometrical confinement. The Capillary Plasma Electrode (CPE) discharge is able to produce stable atmospheric pressure nonequilibrium plasmas. The CPE is similar in design to a barrier-electrode discharge, but has perforated dielectrics. This configuration, aside from exhibiting a diffuse mode of operation, also exhibits the so-called ``capillary jet'' mode, in which the capillaries ``turn on'' and a bright plasma jet emerges from the capillaries. The capillary jets from adjacent capillaries overlap so that the discharge appears uniform when the electrode contains an array of holes. There appears to be a threshold frequency for the capillary jet formation, which is strongly dependent on the L/D ratio of the capillaries, where D is the diameter of a capillary and L its length. This current work explores these modes of operation of the CPE by characterizing the electrical and optical emission properties of this discharge.

  7. Modeling and simulation of plasma gas flow driven by a single nanosecond-pulsed dielectric barrier discharge

    Science.gov (United States)

    Xu, S. Y.; Cai, J. S.; Li, J.

    2016-10-01

    A simplified (7 species and 9 processes) plasma kinetic model is proposed to investigate the mechanism of the plasma aerodynamic actuation driven by nanosecond-pulsed dielectric barrier discharge (NS-DBD). The governing equations include conservation equations for each species, the Poisson equation for the electric potential, and Navier-Stokes equations for the gas dynamic flow. Numerical simulations of plasma discharge and flow actuation on NS-DBD plasma actuators have been carried out. Key discharge characteristics and the responses of the quiescent air were reproduced and compared to those obtained in experiments and numerical simulations. Results demonstrate that the reduced plasma kinetic model is able to capture the dominant species and reactions to predict the actuation in complicated hydrodynamics. For the one-dimensional planar and two-dimensional symmetric NS-DBD, the forming of the sheath collapse is mainly due to the charge accumulation and secondary emission from the grounded electrode. Rapid species number density rise and electric field drop occur at the edge of the plasma sheath, where the space charge density gradient peaks. For the aerodynamic actuation with typical asymmetry electrodes, discharge characteristics have a core area on the right edge of the upper electrode, where the value can be much higher. The formation and propagation of the compression waves generated through rapid heating have also been performed and compared to those measured in a recent experiment. Energy release leads to gas expansion and forms a cylindrical shock wave, centering at the upper electrode tip with low gas acceleration. For the present single pulsed 12 kV case, the mean temperature of gas heating reaches about 575 K at 1 μs and decreases to about 460 K at 10 μs.

  8. Simulations of low field helicon discharges using a two-dimensional hybrid plasma equipment model

    Energy Technology Data Exchange (ETDEWEB)

    Kinder, R.L.; Kushner, M.J.

    1999-07-01

    As the semiconductor industry moves towards larger wafers, a greater degree of process uniformity than is currently available with conventional inductively coupled plasma reactors will be necessary. Due to their high ionization efficiency, high flux density and their ability to deposit power within the volume of the plasma, helicon reactors are being developed for downstream etching and deposition. The power coupling of the antenna radiation to the plasma is of concern due to issues related to process uniformity. Furthermore, operation of helicon discharges at low magnetic fields (5--20 G) is not only economically attractive, but lower fields provide greater ion flux uniformity to the substrate. At low magnetic fields, it has been observed that there is a resonant peak in the power deposition and plasma density. This has been attributed to the occurrence of an electron cyclotron wave, or Trivelpiece-Gould (TG) mode, when {omega}/{omega}{sub c} is of order unity. To investigate these issues, the authors have improved the electromagnetics module of the HPEM to resolve the helicon wave structure of a m = 0 mode. The electrostatic component of the wave equation has been neglected, so this work focuses on the effects of the helicon mode. Plasma dynamics are coupled to the electromagnetic fields through a tensor form of Ohm's law and an effective collision frequency for Landau damping has been incorporated. Using a solenoidal magnetic field and an antenna operating at 13.65 MHz, studies show a shift in the power deposition towards the center of the reactor as the magnetic field is decreased below 30 G. Furthermore, peak values and wave structure is sensitive to the magnetic field configuration. Results for process relevant gas mixtures are examined and the dependence on magnetic field strength, field configuration and power are discussed.

  9. Laser-guided energetic discharges over large air gaps by electric-field enhanced plasma filaments

    Science.gov (United States)

    Théberge, Francis; Daigle, Jean-François; Kieffer, Jean-Claude; Vidal, François; Châteauneuf , Marc

    2017-01-01

    Recent works on plasma channels produced during the propagation of ultrashort and intense laser pulses in air demonstrated the guiding of electric discharges along the laser path. However, the short plasma lifetime limits the length of the laser-guided discharge. In this paper, the conductivity and lifetime of long plasma channels produced by ultrashort laser pulses is enhanced efficiently over many orders of magnitude by the electric field of a hybrid AC-DC high-voltage source. The AC electric pulse from a Tesla coil allowed to stimulate and maintain the highly conductive channel during few milliseconds in order to guide a subsequent 500 times more energetic discharge from a 30-kV DC source. This DC discharge was laser-guided over an air gap length of two metres, which is more than two orders of magnitude longer than the expected natural discharge length. Long plasma channel induced by laser pulses and stimulated by an external high-voltage source opens the way for wireless and efficient transportation of energetic current pulses over long air gaps and potentially for guiding lightning. PMID:28053312

  10. Laser-guided energetic discharges over large air gaps by electric-field enhanced plasma filaments

    Science.gov (United States)

    Théberge, Francis; Daigle, Jean-François; Kieffer, Jean-Claude; Vidal, François; Châteauneuf, Marc

    2017-01-01

    Recent works on plasma channels produced during the propagation of ultrashort and intense laser pulses in air demonstrated the guiding of electric discharges along the laser path. However, the short plasma lifetime limits the length of the laser-guided discharge. In this paper, the conductivity and lifetime of long plasma channels produced by ultrashort laser pulses is enhanced efficiently over many orders of magnitude by the electric field of a hybrid AC-DC high-voltage source. The AC electric pulse from a Tesla coil allowed to stimulate and maintain the highly conductive channel during few milliseconds in order to guide a subsequent 500 times more energetic discharge from a 30-kV DC source. This DC discharge was laser-guided over an air gap length of two metres, which is more than two orders of magnitude longer than the expected natural discharge length. Long plasma channel induced by laser pulses and stimulated by an external high-voltage source opens the way for wireless and efficient transportation of energetic current pulses over long air gaps and potentially for guiding lightning.

  11. Chaotic-to-ordered state transition of cathode-sheath instabilities in DC glow discharge plasmas

    Indian Academy of Sciences (India)

    Md Nurujjaman; A N Sekar Iyengar

    2006-08-01

    Transition from chaotic to ordered state has been observed during the initial stage of a discharge in a cylindrical DC glow discharge plasma. Initially it shows a chaotic behavior but increasing the discharge voltage changes the characteristics of the discharge glow and shows a period subtraction of order 7 period → 5 period → 3 period → 1 period, i.e. the system goes to single mode through odd cycle subtraction. On further increasing the discharge voltage, the system goes through period doubling, like 1 period → 2 period → 4 period. On further increasing the voltage, the system goes to stable state through two period subtraction, like 4 period → 2 period → stable.

  12. Process of commutation of a vacuum electric-discharge gap by laser plasma

    Energy Technology Data Exchange (ETDEWEB)

    Davydov, S. G., E-mail: asvi@mail.ru; Dolgov, A. N.; Kozlovskaya, T. I.; Revazov, V. O.; Seleznev, V. P.; Yakubov, R. Kh. [Dukhov All-Russian Research Institute of Automatics (Russian Federation)

    2016-01-15

    The temporal parameters of a process of vacuum gap commutation under exposure to a nanosecond pulse of laser radiation incident on the cathode has been studied depending on the radiation energy. Based on the experiment data, it is suggested that a glow discharge is initially ignited in electrode erosion products under exposure to the laser pulse, which due to development of the ionization-overheating instability undergoes the contraction of current channel and transits to an arc discharge. With the radiation energy exceeding a threshold value, the radiation (incident on the cathode) accelerates directly the instability development and the glow discharge transition to the arc discharge due to the radiation absorption in the discharge plasma.

  13. Modification of the Steel Surface Treated by a Volume Discharge Plasma in Nitrogen at Atmospheric Pressure

    Science.gov (United States)

    Erofeev, M. V.; Shulepov, M. A.; Ivanov, Yu. F.; Oskomov, K. V.; Tarasenko, V. F.

    2016-03-01

    Effect of volume discharge plasma initiated by an avalanche electron beam on the composition, structure, and properties of the surface steel layer is investigated. Voltage pulses with incident wave amplitude up to 30 kV, full width at half maximum of about 4 ns, and wave front of about 2.5 ns were applied to the gap with an inhomogeneous electric field. Changes indicating the hardening effect of the volume discharge initiated by an avalanche electron beam are revealed in St3-grade steel specimens treated by the discharge of this type.

  14. Non-self-sustained discharge with hollow anode for plasma-based surface treatment

    Directory of Open Access Journals (Sweden)

    Misiruk Ivan O.

    2016-06-01

    Full Text Available The paper discusses plasma methods for surface modification using the non-self-sustained glow discharge with a hollow anode. This discharge is characterised by low voltage and high values of electron and ion currents. It can be easily excited in vacuum-arc installations that are widely used for coatings deposition. It is shown that such type of discharge may be effectively used for ion pumping, film deposition, ion etching, diffusion saturation of metallic materials, fusion and brazing of metals, and for combined application of above mentioned technologies in a single vacuum cycle.

  15. Effect of Dielectric Barrier Discharge Plasma Actuators on Non-equilibrium Hypersonic Flows

    Science.gov (United States)

    2014-10-28

    goes into the kinetic energy of the electrons rather than heating of the surrounding gas.24 The examples of these include corona discharge and micro...and S. P. Wilkinson, “Boundary layer flow control with a one atmosphere uniform glow discharge surface plasma,” AIAA Paper 98 0328, 1998. 4L. Leger, E...Moreau, G. Artana, and G. Touchard, “Influence of a DC corona discharge on the airflow along an inclined flat plate,” J. Electrostat. 51–52, 300 306

  16. Investigation of Vortex Structures in Gas-Discharge Nonneutral Electron Plasma: II. Vortex Formation, Evolution and Dynamics

    CERN Document Server

    Kervalishvili, N A

    2015-01-01

    The results of experimental investigations of inhomogeneities of gas-discharge nonneutral electron plasma obtained by using the nonperturbing experimental methods [N.A. Kervalishvili, arXiv:1502.02516 [physics.plasm-ph] (2015)] have been presented. Inhomogeneities are the dense solitary vortex structures stretched along the magnetic field, the lifetime of which is much greater than the time of electron-neutral collisions. The processes of formation, evolution and dynamics of vortex structures were studied. The periodic sequence of these processes is described for different geometries of discharge device.

  17. Plasma-Surface Interactions in Hollow Cathode Discharges for Electric Propulsion

    Science.gov (United States)

    Capece, Angela Maria

    surface state cannot be obtained because of the cathode geometry and high particles fluxes, measurements of the emitter temperature using a two-color pyrometer were used to determine the oxygen surface coverage and characterize the rate processes that occur during poisoning. A model describing the material transport in the plasma discharge was developed and is used to predict the barium and oxygen fluxes to the emitter surface during cathode operation by solving the species continuity and momentum equations. The dominant ionization process for molecular oxygen in the plasma gas is resonant charge exchange with xenon ions. Barium is effectively recycled in the plasma; however, BaO and O2 are not. The model shows that the oxygen flux to the surface is not diffusion limited. Experimental results indicate that the oxygen poisoning rate is slow and that the oxygen poisoning coverage on the emitter surface is less than 3%. A time-dependent model of the reaction kinetics of oxygen and barium at the tungsten surface was developed using the experimental results. The experiments and kinetics model indicate that the dominant processes at the emitter surface are dissociative adsorption of O2, sputtering of the O2 precursor, and desorption of O. Ion sputtering of the weakly bound O2 precursor state limits the poisoning rate and yields low oxygen coverage. Removal of chemisorbed atomic oxygen is dominated by thermal processes. Based on the low oxygen coverage and long poisoning transients, plasma cathodes appear to be able to withstand higher oxygen concentrations than vacuum cathodes.

  18. Surface Modification of Polyethylene (PE) Films Using Dielectric Barrier Discharge Plasma at Atmospheric Pressure

    Institute of Scientific and Technical Information of China (English)

    WANG Kun; LI Jian; REN Chunsheng; WANG Dezhen; WANG Younian

    2008-01-01

    Modification of the surface properties of polyethylene (PE) films is studied using air dielectric barrier discharge at atmospheric pressure. The treated samples are examined by water contact angle measurements, Fourier transform infrared attenuated total reflection spectroscopy (FTIR-ATR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). With the increase in treating time, the water contact angle changes from 93.2° before treatment to a minimum of 53.3° after a treatment for 50 s. Both ATR and XPS results show some oxidized" species are introduced into the sample surface by the plasma treatment and the tendency of the water contact angle with the treating time is the same as that of oxygen concentration on the treated sample surface. SEM result shows the surface roughness of PE samples increases with the treatment time increasing.

  19. Pulsed Discharge Effects on Bacteria Inactivation in Low-Pressure Radio-Frequency Oxygen Plasma

    Science.gov (United States)

    Vicoveanu, Dragos; Ohtsu, Yasunori; Fujita, Hiroharu

    2008-02-01

    The sporicidal effects of low-pressure radio frequency (RF) discharges in oxygen, produced by the application of continuous and pulsed RF power, were evaluated. For all cases, the survival curves showed a biphasic evolution. The maximum efficiency for bacteria sterilization was obtained when the RF power was injected in the continuous wave mode, while in the pulsed mode the lowest treatment temperature was ensured. The inactivation rates were calculated from the microorganism survival curves and their dependencies on the pulse characteristics (i.e., pulse frequency and duty cycle) were compared with those of the plasma parameters. The results indicated that the inactivation rate corresponding to the first phase of the survival curves is related to the time-averaged intensity of the light emission by the excited neutral atoms in the pulsed plasma, whereas the inactivation rate calculated from the second slope of the survival curves and the time-averaged plasma density have similar behaviors, when the pulse parameters were modified.

  20. Discharge electrode configuration effects on the performance of a plasma sparker

    Science.gov (United States)

    Pei, Yanliang; Zhang, Liancheng; Huang, Yifan; Yan, Hui; Zhu, Xinlei; Liu, Zhen; Yan, Keping

    2017-09-01

    A multi-electrode array is commonly applied in a plasma sparker to generate stable acoustic pulses. In this paper, the effects of the electrode configuration on the performance of a plasma sparker have been investigated. In terms of the load electrical characteristics, the electrode radius and distance have negligible influence on the electric characteristics, whereas a larger electrode number results in a smaller voltage and a larger current but has little effect on the load energy. Regarding the acoustic characteristics, both the expansion and collapse pulses can be increased by decreasing the electrode tip radius. the influence of the electrode number and electrode gap distance on the amplitude of the expansion pulse was found to be negligible. And the amplitude of the collapse pulse decreases significantly with increasing electrode number. Increasing the electrode number decreases the energy efficiency for intense bubble interactions, thus, a small electrode tip radius and a small electrode number are preferred for the design of a plasma sparker if the total discharge energy is given.

  1. Measurement Of Plasma Parameters In Micro-Discharge By Wall Probe

    Science.gov (United States)

    Saifutdinov, Almaz; Kudryavtsev, Anatoly; Sysoev, Sergey

    2016-09-01

    The increasing scientific and practical interest for glow discharge at high pressure is largely determined by the fact that their use does not require expensive and huge vacuum equipment. The analysis shows that, in contrast to the well-studied positive column (PC), the basic parameters of the plasma negative glow (NG) and Faraday dark space (FDS) of micro-discharges are studied insufficiently. The difficulties of the experimental diagnostics are associated with the fact that for the fixed values of pL with the increasing gas pressure the length of the micro-discharge decreases. And a small size is extremely difficult to diagnose spatial parameters distribution of micro discharges. Since at a small size introducing traditional Langmuir probe into the plasma capacity is not possible technically, it was proposed to use an additional measuring electrode (wall probe) disposed between the cathode and the anode for measurement of the fast EEDF. With its use we have registered EEDF fast electrons produced in the reaction of Penning ionization out of earlier reach range of high-pressure gas (from 20 to 200 Torr). In this paper by using wall probe we measured the basic parameters of NG plasma in micro-discharge in helium in a wide range of pressures. It is shown that the electrons temperature in the NG plasma is low and amounts to few fraction of 1 eV, which differs from the electron temperature in PC plasma. This allows the use of NG plasma for analysis by gas plasma electron spectroscopy. Authors thanks RNF (Grant 14-19-00311) for the support.

  2. Effects of Boundary Layer Flow Control Using Plasma Actuator Discharges

    Science.gov (United States)

    2005-09-01

    have run tests in this area to demonstrate plasma actuators as ailerons and winglets , as well as to reduce separation on low pressure turbine (LPT...ray component of the SEM computed the elemental composition percentages of the plate. For aluminum oxide, a 3-to-2 ratio of oxygen to aluminum was...desired. However, the electron microscopy revealed that manganese was present in the composition , due to impurities in the aluminum. Figure 13

  3. Self-consistent evolution of plasma discharge and electromagnetic fields in a microwave pulse compressor

    Energy Technology Data Exchange (ETDEWEB)

    Shlapakovski, A. S.; Beilin, L.; Krasik, Ya. E. [Physics Department, Technion 32000 Haifa (Israel); Hadas, Y. [Department of Applied Physics, Rafael, POBox 2250, Haifa 31021 (Israel); Schamiloglu, E. [Department of Electrical and Computer Engineering, University of New Mexico, Albuquerque, New Mexico 87131 (United States)

    2015-07-15

    Nanosecond-scale evolution of plasma and RF electromagnetic fields during the release of energy from a microwave pulse compressor with a plasma interference switch was investigated numerically using the code MAGIC. The plasma was simulated in the scope of the gas conductivity model in MAGIC. The compressor embodied an S-band cavity and H-plane waveguide tee with a shorted side arm filled with pressurized gas. In a simplified approach, the gas discharge was initiated by setting an external ionization rate in a layer crossing the side arm waveguide in the location of the electric field antinode. It was found that with increasing ionization rate, the microwave energy absorbed by the plasma in the first few nanoseconds increases, but the absorption for the whole duration of energy release, on the contrary, decreases. In a hybrid approach modeling laser ignition of the discharge, seed electrons were set around the electric field antinode. In this case, the plasma extends along the field forming a filament and the plasma density increases up to the level at which the electric field within the plasma decreases due to the skin effect. Then, the avalanche rate decreases but the density still rises until the microwave energy release begins and the electric field becomes insufficient to support the avalanche process. The extraction of the microwave pulse limits its own power by terminating the rise of the plasma density and filament length. For efficient extraction, a sufficiently long filament of dense plasma must have sufficient time to be formed.

  4. Self-consistent evolution of plasma discharge and electromagnetic fields in a microwave pulse compressor

    Science.gov (United States)

    Shlapakovski, A. S.; Beilin, L.; Hadas, Y.; Schamiloglu, E.; Krasik, Ya. E.

    2015-07-01

    Nanosecond-scale evolution of plasma and RF electromagnetic fields during the release of energy from a microwave pulse compressor with a plasma interference switch was investigated numerically using the code MAGIC. The plasma was simulated in the scope of the gas conductivity model in MAGIC. The compressor embodied an S-band cavity and H-plane waveguide tee with a shorted side arm filled with pressurized gas. In a simplified approach, the gas discharge was initiated by setting an external ionization rate in a layer crossing the side arm waveguide in the location of the electric field antinode. It was found that with increasing ionization rate, the microwave energy absorbed by the plasma in the first few nanoseconds increases, but the absorption for the whole duration of energy release, on the contrary, decreases. In a hybrid approach modeling laser ignition of the discharge, seed electrons were set around the electric field antinode. In this case, the plasma extends along the field forming a filament and the plasma density increases up to the level at which the electric field within the plasma decreases due to the skin effect. Then, the avalanche rate decreases but the density still rises until the microwave energy release begins and the electric field becomes insufficient to support the avalanche process. The extraction of the microwave pulse limits its own power by terminating the rise of the plasma density and filament length. For efficient extraction, a sufficiently long filament of dense plasma must have sufficient time to be formed.

  5. Influence of the gap size and dielectric constant of the packing on the plasma discharge in a packed bed dielectric barrier discharge reactor: a fluid modeling study

    Science.gov (United States)

    van Laer, Koen; Bogaerts, Annemie

    2016-09-01

    Packed bed dielectric barrier discharge (DBD) reactors have proven to be very useful sources of non-thermal plasma for a wide range of applications, of which the environmental applications have received most attention in recent years. Compared to an empty DBD reactor, a packing was introduced to either enhance the energy efficiency of the process, or, if the packing is catalytically active, steer the process towards a preferred end product. A wide range of geometries, bead sizes and bead materials have been tested experimentally in the past. However, since experimental diagnostics become more difficult with a packing present, a computational study is proposed to gain more insight. Using COMSOL's built in plasma module, a 2D axisymmetric fluid model is developed to study the influence of the gap size and the dielectric constant (ɛ) of the packing. Helium is used as discharge gas, at atmospheric pressure and room temperature. By decreasing the gas gap, the electric field strength is enhanced, resulting in a higher number of current peaks per half cycle of applied rf potential. Increasing ɛ also enhances the electric field strength. However, after a certain ɛ, its influence saturates. The electric field strength will no longer increase, leaving the discharge behavior unchanged.

  6. Study on structural, morphological and thermal properties of surface modified polyvinylchloride (PVC) film under air, argon and oxygen discharge plasma

    Science.gov (United States)

    Suganya, Arjunan; Shanmugavelayutham, Gurusamy; Serra Rodríguez, Carmen

    2016-09-01

    The effect of air, argon, oxygen DC glow discharge plasma on the polyvinylchloride (PVC) film synthesized by solution casting technique, were evaluated via changes in physio-chemical properties such as structural, morphological, crystalline, thermal properties. The PVC film was plasma treated as a function of exposure time and different plasma forming gases, while other operating parameters such as power and pressure remained constant at 100 W and 2 Pa respectively. The plasma treated PVC were characterized by static contact angle, ATR-FTIR, XPS, AFM and T-peel analysis. It was found that various gaseous plasma treatments have improved the polar components, surface roughness on the surface of PVC which was confirmed by XPS, AFM, resulting in highly enhanced wettability and adhesion. X-ray diffraction study showed that plasma treatment does not persuade considerable change, even though it vaguely induces the crystallinity. The thermal properties of plasma treated PVC were evaluated by Differential Scanning Calorimetry and it was observed that O2 plasma treatment gives higher glass transition temperature of 87.21 °C compared with the untreated one. The glass transition temperature slightly increased for Oxygen plasma treated material due to the presence of higher concentration of the polar functional groups on the PVC surface due to strong intramolecular bonding.

  7. Effect of DC glow discharge plasma treatment on PET/TiO(2) thin film surfaces for enhancement of bioactivity.

    Science.gov (United States)

    Navaneetha Pandiyaraj, K; Selvarajan, V; Rhee, Young Ha; Kim, Hyoung Woo; Pavese, Matteo

    2010-08-01

    In this paper, the surfaces of PET/TiO(2) thin film were modified by DC glow discharge plasma as a function of discharge potentials for improving the bioactivity. The hydrophilicity of the plasma-treated PET/TiO(2) film was measured by contact angle measurement and the surface energy was estimated by using Fowkes method. The structural and chemical composition of the plasma-treated PET/TiO(2) was analysed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Immersion in a simulated body solution (SBF) solution was used to evaluate the bioactivity of the plasma-treated PET/TiO(2) samples in vitro. It was found that the plasma treatment modified the surfaces both in chemical composition and crystallinity which makes surface of the PET/TiO(2) to become more hydrophilic compared with untreated one. Analytical and microstructural investigations of SBF results, showed considerable higher rates of apatite formation on the plasma-treated PET/TiO(2) compared to the untreated films.

  8. The relation between doses or post-plasma time points and apoptosis of leukemia cells induced by dielectric barrier discharge plasma

    Directory of Open Access Journals (Sweden)

    Chao Wang

    2015-12-01

    Full Text Available The dielectric barrier discharge (DBD plasma was applied to induce apoptosis of LT-12 leukemia cells. Plasma effects on cell death was evaluated by MTT assay and FCM apoptosis assay with Annexin V/PI double staining, suggesting that plasma killing cells rate and inducing cell apoptosis rate both positively were related to the plasma doses or the post-plasma time points. The cell death rates increased from 15.2% to 33.1% and the apoptosis rate raise from 23.8% to 28% when the dose raise from 60s to 120 s at 8 h post-plasma, while they increased from 15.4% to 34.9% and from 48% to 55.3% respectively at the same doses at 12 h post-plasma. Furthermore, the production of reactive oxygen species (ROS, gene and protein expression for Caspases and Bcl-2 family members were measured for exploring the related apoptotic mechanisms phenomenon. We found ROS immediately increased to 1.24 times of the original amount, then increasing to 5.39-fold at 20 h after treatment. The gene and protein expression for Caspases and Bcl-2 family members are very active at 8-12 h post-plasma. Our results demonstrate that DBD plasma can effectively induce tumor cell death through primarily related apoptotic mechanisms.

  9. Further investigations on the Neutron Flux Generation in a Plasma Discharge Electrolytic Cell

    CERN Document Server

    Faccini, R; Polosa, A D; Angelone, M; Castagna, E; Lecci, S; Loreti, S; Pietropaolo, A; Pillon, M; Sansovini, M; Sarto, F; Violante, V; Bedogni, R; Esposito, A

    2014-01-01

    Our recent paper on the "Search for Neutron Flux Generation in a Plasma Discharge Electrolytic Cell" [1] has as main goal the validation of the experiment in Ref.[2]. As a follow-up, Ref.[3] moves a set of objections on our procedure and presents argumentations on why the experiments should not yield the same results. We collect here additional material and calculations that contribute to understanding the observed discrepancies. Furthermore we prove that the absence of signals from Indium activation detectors reported also for the experiment of Ref.[2] is a clear indication that neutron production does not occur. [1] R.Faccini et al arXiv:1310.4749 [2] D.Cirillo et al, Key Engineering Materials 495, 104 (2012). [3] A.Widom et al. arXiv:1311.2447

  10. Investigation of Plasma Polymerized Maleic Anhydride Film in a Middle Frequency Dielectric Barrier Discharge

    Institute of Scientific and Technical Information of China (English)

    TANG Wenjie; CHEN Qiang; ZHANG Yuefei; GE Yuanjing

    2008-01-01

    Plasma polymerized maleic anhydride (MA) was carried out by using maleic anhydride supersaturated ethanol solution as a precursor in a dielectric barrier discharge (DBD). The film properties were characterized by water contact angle (WCA), Fourier transfer infrared (FTIR), X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM) analysis, and a thickness profilometer. The influence of the processing parameters on the film properties such as the power frequency, and polymerization zone was investigated. The results show that anhydride group incorporated into the growing films is favorable at the frequency of 80 kHz and working pressure of 50 Pa. The poly (maleic anhydride) film is uniform and compact at an average deposition rate of 8 nm/min.

  11. Conversion of carbon dioxide to carbon monoxide by pulse dielectric barrier discharge plasma

    Science.gov (United States)

    Wang, Taobo; Liu, Hongxia; Xiong, Xiang; Feng, Xinxin

    2017-01-01

    The conversion of carbon dioxide (CO2) to carbon monoxide (CO) was investigated in a non-thermal plasma dielectric barrier discharge (DBD) reactor, and the effects of different process conditions on the CO2 conversion were investigated. The results showed that the increase of input power could optimize the conversion of CO2 to CO. The CO2 conversion and CO yield were negatively correlated with the gas flow rate, but there was an optimum gas flow rate, that made the CO selectivity best. The carrier gas (N2, Ar) was conducive to the conversion of CO2, and the effect of N2 as carrier gas was better than Ar. The conversion of CO2 to CO was enhanced by addition of the catalyst (5A molecular sieve).

  12. Simulation of plasma discharge in liquids: A detailed two-phase fluid approach

    Science.gov (United States)

    Charchi Aghdam, Ali; Farouk, Tanvir; Reacting Systems; Advanced Energy Research Laboratory Team

    2015-09-01

    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.

  13. Influence of Plasma Jet Temperature Profiles in Arc Discharge Methods of Carbon Nanotubes Synthesis

    Directory of Open Access Journals (Sweden)

    Grzegorz Raniszewski

    2017-02-01

    Full Text Available One of the most common methods of carbon nanotubes (CNTs synthesis is application of an electric-arc plasma. However, the final product in the form of cathode deposit is composed of carbon nanotubes and a variety of carbon impurities. An assay of carbon nanotubes produced in arc discharge systems available on the market shows that commercial cathode deposits contain about 10% CNTs. Given that the quality of the final product depends on carbon–plasma jet parameters, it is possible to increase the yield of the synthesis by plasma jet control. Most of the carbon nanotubes are multiwall carbon nanotubes (MWCNTs. It was observed that the addition of catalysts significantly changes the plasma composition, effective ionization potential, the arc channel conductance, and in effect temperature of the arc and carbon elements flux. This paper focuses on the influence of metal components on plasma-jet forming containing carbon nanotubes cathode deposit. The plasma jet temperature control system is presented.

  14. Dielectric material degradation monitoring of dielectric barrier discharge plasma actuators

    Science.gov (United States)

    Hanson, Ronald E.; Houser, Nicole M.; Lavoie, Philippe

    2014-01-01

    It is a known phenomenon that some dielectric materials used to construct plasma actuators degrade during operation. However, the rate at which this process occurs, to what extent, as well as a method to monitor is yet to be established. In this experimental study, it is shown that electrical measurements can be used to monitor changes in the material of the plasma actuators. The procedure we introduce for monitoring the actuators follows from the work of Kriegseis, Grundmann, and Tropea [Kriegseis et al., J. Appl. Phys. 110, 013305 (2011)], who used Lissajous figures to measure actuator power consumption and capacitance. In the present study, we quantify changes in both the power consumption and capacitance of the actuators over long operating durations. It is shown that the increase in the effective capacitance of the actuator is related to degradation (thinning) of the dielectric layer, which is accompanied by an increase in actuator power consumption. For actuators constructed from layers of Kapton® polyimide tape, these changes are self-limiting. Although the polyimide film degrades relatively quickly, the underlying adhesive layer appears to remain intact. Over time, the effective capacitance was found to increase by up to 36%, 25%, and 11% for actuators constructed with 2, 3, and 4 layers of Kapton tape, respectively. A method is presented to prevent erosion of the Kapton dielectric layer using a coating of Polydimethylsiloxane oil. It is shown the application of this treatment can delay the onset of degradation of the Kapton dielectric material.

  15. Comparison between measured scrape-off layer plasma parameters and 2D model calculations for JET X-point discharges

    Energy Technology Data Exchange (ETDEWEB)

    Loarte, A. [JET Joint Undertaking, Abingdon, Oxon, OX14 3EA (United Kingdom); Chankin, A. [JET Joint Undertaking, Abingdon, Oxon, OX14 3EA (United Kingdom); Clement, S. [JET Joint Undertaking, Abingdon, Oxon, OX14 3EA (United Kingdom); Corrigan, G. [JET Joint Undertaking, Abingdon, Oxon, OX14 3EA (United Kingdom); Harbour, P. [JET Joint Undertaking, Abingdon, Oxon, OX14 3EA (United Kingdom); Horton, L. [JET Joint Undertaking, Abingdon, Oxon, OX14 3EA (United Kingdom); Janeschitz, G. [JET Joint Undertaking, Abingdon, Oxon, OX14 3EA (United Kingdom); Lingertat, J. [JET Joint Undertaking, Abingdon, Oxon, OX14 3EA (United Kingdom); Matthews, G. [JET Joint Undertaking, Abingdon, Oxon, OX14 3EA (United Kingdom); Simonini, R. [JET Joint Undertaking, Abingdon, Oxon, OX14 3EA (United Kingdom); Tagle, J.A. [JET Joint Undertaking, Abingdon, Oxon, OX14 3EA (United Kingdom); Taroni, A. [JET Joint Undertaking, Abingdon, Oxon, OX14 3EA (United Kingdom); Vlases, G. [JET Joint Undertaking, Abingdon, Oxon, OX14 3EA (United Kingdom)

    1995-04-01

    Modelling with the EDGE2D/U-NIMBUS code of the measured scrape-off layer plasma parameters for JET divertor discharges is presented. Model results agree with the experiment if very small values (< or {approx}0.1 m{sup 2}/s in H-modes and low power L-modes) for the anomalous particle transport diffusion coefficient in the SOL are used. While the assumption of the power flow out of the main plasma being carried equally by the electrons and the ions describes satisfactorily the global power balance for Ohmic and L-mode discharges, more power flowing out through the ion channel is consistent with the power balance in hot ion H-modes. Some sensitivity studies of the code results on the modelling hypothesis are discussed. ((orig.)).

  16. Influence of discharge and jet flow coupling on atmospheric pressure plasma homogeneity

    Science.gov (United States)

    Nizard, H.; Gaudy, T.; Toutant, A.; Iacono, J.; Descamps, P.; Leempoel, P.; Massines, F.

    2015-10-01

    The effect of flow dynamics on the discharge mode is studied in order to design a technical solution for thin film coating on large surfaces. The configuration consists in two atmospheric pressure helium plasma jets impacting a surface and confined in a tube. This system operates in open air. It has been studied by short exposure time pictures, current and voltage measurements, optical emission spectroscopy, schlieren flow visualization and computational fluid dynamics. Two discharge regimes directly connected to the gas flow dynamic have been pointed out. One is localized from the point electrodes to the surface; the other one entirely fills the confinement tube. A correlation between air intake inside the confinement tube and the discharge mode has been highlighted. Indeed, the discharge only develops in helium and the air intake confines the helium jets in volumes smaller than the confinement tube. The air intake is determined by the gas flow rate and the distance from the tube bottom to the substrate surface, parameters which have been linked to the change from laminar to turbulent flow. Finally, the understanding of flow dynamics and discharge plasma coupling allowed the design of a technical solution favoring plasma homogeneity for large surface treatment.

  17. Modeling plasma glow discharges in Air near a Mach 3 bow shock with KRONOS

    Science.gov (United States)

    Rassou, Sebastien; Labaune, Julien; Packan, Denis; Elias, Paul-Quentin

    2016-09-01

    In this work, plasma glow discharge in Air is modeled near a Mach 3 bow shock. Numerical simulations are performed using the coupling KRONOS which have been developed at ONERA. The flow field is modeled using the code CFD: CEDRE from ONERA and the electrical and plasma part by the EDF open-source code CODE_SATURNE. The plasma kinetic modeling consists on a two-term Boltzmann equation solver and a chemical reaction solver depending of the electric field. The coupling KRONOS is fully parallelized and run on ONERA supercomputers. The shock wave is formed by the propagation of a supersonic flow (M = 3) through a truncated conical model mounted with a central spike. Depending on the spike's voltage value, corona, glow or arc regime could be obtained in a steady flow. The parameters for the supersonic flow and the spike configurations are chosen to be in glow discharge regime and to reproduce the experimental setup. In our simulations, 12 species and 80 reactions (ionization, electronic or vibrational excitation, attachment etc ...) are considered to properly model the glow discharge and the afterglow. In a stationary flow, glow discharge is observed only at the upstream of the shock wave near the high voltage spike. Behind the bow shock, in the afterglow, negative ions are provided by electrons attachment with O2. The negative ions flow convection ensures the electrical conduction and the establishment of the glow discharge.

  18. Thrust Stand Measurements of the Microwave Assisted Discharge Inductive Plasma Accelerator

    Science.gov (United States)

    Hallock, Ashley K.; Polzin, Kurt A.; Emsellem, Gregory D.

    2011-01-01

    Pulsed inductive plasma thrusters [1-3] are spacecraft propulsion devices in which electrical energy is capacitively stored and then discharged through an inductive coil. This type of pulsed thruster is electrodeless, with a time-varying current in the coil interacting with a plasma covering the face of the coil to induce a plasma current. Propellant is accelerated and expelled at a high exhaust velocity (O(10-100 km/s)) by the Lorentz body force arising from the interaction of the magnetic field and the induced plasma current. While this class of thruster mitigates the life-limiting issues associated with electrode erosion, pulsed inductive plasma thrusters require high pulse energies to inductively ionize propellant. The Microwave Assisted Dis- charge Inductive Plasma Accelerator (MAD-IPA), shown in Fig. 1, is a pulsed inductive plasma thruster that addressees this issue by partially ionizing propellant inside a conical inductive coil before the main current pulse via an electron cyclotron resonance (ECR) discharge. The ECR plasma is produced using microwaves and a static magnetic field from a set of permanent magnets arranged to create a thin resonance region along the inner surface of the coil, restricting plasma formation, and in turn current sheet formation, to a region where the magnetic coupling between the plasma and the theta-pinch coil is high. The use of a conical theta-pinch coil also serves to provide neutral propellant containment and plasma plume focusing that is improved relative to the more common planar geometry of the Pulsed Inductive Thruster (PIT) [1, 2]. In this paper, we describe thrust stand measurements performed to characterize the performance (specific impulse, thrust efficiency) of the MAD-IPA thruster. Impulse data are obtained at various pulse energies, mass flow rates and inductive coil geometries. Dependencies on these experimental parameters are discussed in the context of the current sheet formation and electromagnetic plasma

  19. Etching of UO{sub 2} in NF{sub 3} RF Plasma Glow Discharge

    Energy Technology Data Exchange (ETDEWEB)

    John M. Veilleux

    1999-08-01

    A series of room temperature, low pressure (10.8 to 40 Pa), low power (25 to 210 W) RF plasma glow discharge experiments with UO{sub 2} were conducted to demonstrate that plasma treatment is a viable method for decontaminating UO{sub 2} from stainless steel substrates. Experiments were conducted using NF{sub 3} gas to decontaminate depleted uranium dioxide from stainless-steel substrates. Depleted UO{sub 2} samples each containing 129.4 Bq were prepared from 100 microliter solutions of uranyl nitrate hexahydrate solution. The amorphous UO{sub 2} in the samples had a relatively low density of 4.8 gm/cm{sub 3}. Counting of the depleted UO{sub 2} on the substrate following plasma immersion was performed using liquid scintillation counting with alpha/beta discrimination due to the presence of confounding beta emitting daughter products, {sup 234}Th and {sup 234}Pa. The alpha emission peak from each sample was integrated using a gaussian and first order polynomial fit to improve quantification. The uncertainties in the experimental measurement of the etched material were estimated at about {+-} 2%. Results demonstrated that UO{sub 2} can be completely removed from stainless-steel substrates after several minutes processing at under 200 W. At 180 W and 32.7 Pa gas pressure, over 99% of all UO{sub 2} in the samples was removed in just 17 minutes. The initial etch rate in the experiments ranged from 0.2 to 7.4 {micro}m/min. Etching increased with the plasma absorbed power and feed gas pressure in the range of 10.8 to 40 Pa. A different pressure effect on UO{sub 2} etching was also noted below 50 W in which etching increased up to a maximum pressure, {approximately}23 Pa, then decreased with further increases in pressure.

  20. Energy deposition characteristics of nanosecond dielectric barrier discharge plasma actuators: Influence of dielectric material

    NARCIS (Netherlands)

    Correale, G.; Winkel, R.; Kotsonis, M.

    2015-01-01

    An experimental study aimed at the characterization of energy deposition of nanosecond Dielectric Barrier Discharge (ns-DBD) plasma actuators was carried out. Special attention was given on the effect of the thickness and material used for dielectric barrier. The selected materials for this study we

  1. PREFACE: 12th International Conference on Gas Discharge Plasmas and Their Applications

    Science.gov (United States)

    Koval, N.; Landl, N.; Bogdan, A.; Yudin, A.

    2015-11-01

    The 12th International Conference ''Gas Discharge Plasmas and Their Applications'' (GDP 2015) was held in Tomsk, Russia, on September 6-11, 2015. GDP 2015 represents a continuation of the conferences on physics of gas discharge held in Russia since 1984 and seminars and conferences on the technological applications of low temperature plasmas traditionally organized in Tomsk. The six-day Conference brought together the specialists from different countries and organizations and provided an excellent opportunity to exchange knowledge, make oral contributions and poster presentations, and initiate discussions on the topics that are of interest to the Conference participants. The selected papers of the Conference cover a wide range of technical areas and modern aspects of the physical processes in the generators of low-temperature plasma, the low and high-pressure discharges, the pulsed plasma sources, the surface modification, and other gas-discharge technologies. The Conference was hosted by Institute of High Current Electronics SB RAS, Tomsk Polytechnic University, Tomsk Scientific Center, and Tomsk State University of Architecture and Building.

  2. Measurements of 3D slip velocities and plasma column lengths of a gliding arc discharge

    NARCIS (Netherlands)

    Zhu, J.; Gao, J.; Ehn, A.; Alden, M.; Li, Z.; Moseev, D.; Kusano, Y.; Salewski, M.; Alpers, A.; Gritzmann, P.; Schwenk, M.

    2015-01-01

    A non-thermal gliding arc discharge was generated at atmospheric pressure in an air flow. The dynamics of the plasma column and tracer particles were recorded using two synchronized highspeed cameras. Whereas the data analysis for such systems has previously been performed in 2D (analyzing the singl

  3. Method of preparing water purification membranes. [polymerization of allyl amine as thin films in plasma discharge

    Science.gov (United States)

    Hollahan, J. R.; Wydeven, T. J., Jr. (Inventor)

    1974-01-01

    Allyl amine and chemically related compounds are polymerized as thin films in the presence of a plasma discharge. The monomer compound can be polymerized by itself or in the presence of an additive gas to promote polymerization and act as a carrier. The polymerized films thus produced show outstanding advantages when used as reverse osmosis membranes.

  4. A Study on Water Treatment Induced by Plasma with Contact Glow Discharge Electrolysis

    Institute of Scientific and Technical Information of China (English)

    胡中爱; 王晓艳; 高锦章; 邓华陵; 侯经国; 卢小泉; 康敬万

    2001-01-01

    Oxidative degradation of eight kinds of dyes induced by plasma in aqueous solution was investigated with contact glow discharge electrolysis (CGDE). It has been demonstrated that these eight dyes underwent degradation in CGDE, where Fe2+ could be utilised to raise the efficiency of degradation of dyes.

  5. Rotating plasma structures in the cross-field discharge of Hall thrusters

    Science.gov (United States)

    Mazouffre, Stephane; Grimaud, Lou; Tsikata, Sedina; Matyash, Konstantin

    2016-09-01

    Rotating plasma structures, also termed rotating spokes, are observed in various types of low-pressure discharges with crossed electric and magnetic field configurations, such as Penning sources, magnetron discharges, negative ion sources and Hall thrusters. Such structures correspond to large-scale high-density plasma blocks that rotate in the E×B drift direction with a typical frequency on the order of a few kHz. Although such structures have been extensively studied in many communities, the mechanism at their origin and their role in electron transport across the magnetic field remain unknown. Here, we will present insights into the nature of spokes, gained from a combination of experiments and advanced particle-in-cell numerical simulations that aim at better understanding the physics and the impact of rotating plasma structures in the ExB discharge of the Hall thruster. As rotating spokes appear in the ionization region of such thrusters, and are therefore difficult to probe with diagnostics, experiments have been performed with a wall-less Hall thruster. In this configuration, the entire plasma discharge is pushed outside the dielectric cavity, through which the gas is injected, using the combination of specific magnetic field topology with appropriate anode geometry.

  6. Physical and chemical properties of dust produced in a N2-CH4 RF plasma discharge

    Science.gov (United States)

    Ouni, F.; Adande, G.; Thissen, R.; Alcouffe, G.; Szopa, C.; Schmitz-Afonso, I.; Laprévote, O.; Quirico, E.; Brissaud, O.; Carrasco, N.; Cernogora, G.

    2008-09-01

    Titan's atmospheric chemistry is simulated using a Capacitively Coupled Plasma discharge produced in a N2-CH4 mixture. The produced solid particles are analysed ex-situ. Chemical properties are deduced from: elemental composition, FTIR and LTQ-Orbitrap mass spectrometer. Optical properties are deduced from reflectivity in visible and IR range.

  7. Supersonic flow of a nonequilibrium gas-discharge plasma around a body

    Science.gov (United States)

    Lapushkina, T. A.; Erofeev, A. V.; Ponyaev, S. A.; Bobashev, S. V.

    2009-06-01

    The flow of a nonequilibrium gas-discharge plasma around a semicylindrical body is studied. The aim of the study is to see how a change in the degree of nonequilibrium of the incoming plasma changes the separation distance between a shock wave and the body. Experiments are carried out with a supersonic nozzle into which a semicylindrical body is placed. The inlet of the nozzle is connected to a shock tube. In the course of the experiment, electrodes built into the wall of the nozzle initiate a gas discharge in front of the body to produce an additional nonequilibrium ionization in the stationary incoming supersonic flow. The discharge parameters are selected such that the discharge raises the electron temperature and still minimizes heating of the gas. The degree of nonequilibrium of the flow varies with gas-discharge current. Diagnostics of the flow is carried out with a schlieren system based on a semiconductor laser. The system can record flow patterns at definite time instants after discharge initiation.

  8. Charging of dust grains in a nonequilibrium plasma of a stratified glow discharge

    Science.gov (United States)

    Sukhinin, G. I.; Fedoseev, A. V.

    2007-12-01

    A theoretical model is presented that describes the charging of dust grains in the positive plasma column of a stratified glow dc discharge in argon. A one-dimensional self-consistent model is used to obtain axial profiles of the electric field, as well as the electron energy distribution function along the axis of the discharge tube. Radial profiles of the electric field are determined in the ambipolar diffusion approximation. It is assumed that, in the radial direction, the electron distribution function depends only on the total electron energy. Two-dimensional distributions of the discharge plasma parameters are calculated and used to determine the potential and charge of a test dust grain at a certain point within the discharge and the electrostatic forces acting on it. It is shown that the grain charge distribution depends strongly on the nonequilibrium electron distribution function and on the nonuniform distribution of the electric field in a stratified glow discharge. A discussion is presented on the suspension of dust grains, the separation of grains by size in the discharge striations, and a possible mechanism for the onset of vortex dust motion at the edge of a dust cloud.

  9. Partial oxidation of methane to methanol with nitrogen dioxide in dielectric barrier discharge plasma: experimental and molecular modeling

    Science.gov (United States)

    Indarto, Antonius

    2016-04-01

    Non-catalytic conversion of methane (CH4) and nitrogen dioxide (NO2) into methanol (CH3OH) has been conducted and presented in this paper. Experiments were carried out using dielectric barrier discharge as the reaction medium in atmospheric pressure and temperature conditions. High yield production of methanol was achieved (18-20% mol) by single-stage plasma reaction with maximum selectivity of 32% mol. Compared to other oxidants, such as O2, the presence of NO2 in the plasma reaction resulted in higher methanol selectivity. For better understanding of the reactions, density functional theory calculations were also performed and discussed.

  10. Investigation of complexity dynamics in a DC glow discharge magnetized plasma using recurrence quantification analysis

    Energy Technology Data Exchange (ETDEWEB)

    Mitra, Vramori; Sarma, Bornali; Sarma, Arun [VIT University, Vandalur-Kelambakkam Road, Chennai 600 127, Tamil Nadu (India); Janaki, M. S.; Sekar Iyengar, A. N. [Plasma Physics Division, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata 700064 (India); Marwan, Norbert [Potsdam Institute for Climate Impact Research, PO Box 601203, 14412 Potsdam (Germany); Kurths, Jürgen [Potsdam Institute for Climate Impact Research, PO Box 601203, 14412 Potsdam (Germany); Institute for Complex Systems and Mathematical Biology, University of Aberdeen, Aberdeen AB24 3FX (United Kingdom)

    2016-06-15

    Recurrence is an ubiquitous feature which provides deep insights into the dynamics of real dynamical systems. A suitable tool for investigating recurrences is recurrence quantification analysis (RQA). It allows, e.g., the detection of regime transitions with respect to varying control parameters. We investigate the complexity of different coexisting nonlinear dynamical regimes of the plasma floating potential fluctuations at different magnetic fields and discharge voltages by using recurrence quantification variables, in particular, DET, L{sub max}, and Entropy. The recurrence analysis reveals that the predictability of the system strongly depends on discharge voltage. Furthermore, the persistent behaviour of the plasma time series is characterized by the Detrended fluctuation analysis technique to explore the complexity in terms of long range correlation. The enhancement of the discharge voltage at constant magnetic field increases the nonlinear correlations; hence, the complexity of the system decreases, which corroborates the RQA analysis.

  11. Experimental measurements of the hollow cathode DC glow discharge parameters in Ar and He plasmas

    Science.gov (United States)

    Omrani, M.; Amrollahi, R.; Iraji, D.

    2016-12-01

    In this article, we focus on some of the fundamental parameters of SS316L hollow cathode glow discharge. Four SS316L samples are placed at different locations on the cathode surface and the current passed through them is measured in Ar and He glow discharge plasmas. The wall current densities of Ar and He are in the range of 8-25 µA cm-2 and 8-35 µA cm-2, respectively. Results also show that with decreasing working pressure, the ion flux and current density distribution on the wall surface becomes more uniform. The ion flux of the Ar and He is in the range of 1013 to 1014 ~\\text{ion} \\text{c}{{\\text{m}}-2} . Total energy losses of Ar and He are measured at the pressure range of 1.4-5.5  ×  10-2 torr and 3.2-7.1  ×  10-1, respectively. In both Ar and He, total energy losses decreased with increasing pressure. The secondary electron emission coefficients of Ar and He, which are evaluated for the hallow cathode configuration, are about 0.42 and 0.26, respectively, and are higher in comparison with the plate cathode configuration.

  12. Kinetic analysis of soil contained pyrene oxidation by a pulsed discharge plasma process

    Science.gov (United States)

    Huijuan, Wang; Guangshun, Zhou; He, Guo; Cong, Geng

    2017-01-01

    A pulsed discharge plasma (PDP) reactor with net anode and net cathode was established for investigating the pyrene degradation in soil under different pulse peak voltage, air flow rate, pyrene content in soil, initial pH value and initial water content of the soil. Pyrene oxidation within the 60 min discharge time was fitting according to the pseudo-first order equation and the corresponding reaction kinetics constants (k values) were calculated. The obtained results show that pyrene oxidation under all the different reaction conditions obeyed the pseudo-first order equation well. Higher pulsed peak voltage and appropriate air flow rate were in favor of the increase of reaction rate of pyrene oxidation. A higher k value could be achieved in the lower initial pyrene content (the value was 100 mg kg-1). The k value of pyrene oxidation in the case of pH = 4 was 11.2 times higher than the value obtained under the condition of pH = 9, while the initial water content of the soil also has a large effect on the oxidation rate of pyrene due to the effect of PDP. Supported by National Natural Science Foundation of China (No. 21207052).

  13. Characteristics of gas-liquid pulsed discharge plasma reactor and dye decoloration efficiency

    Institute of Scientific and Technical Information of China (English)

    Bing Sun; Nyein Nyein Aye; Zhiying Gao; Dan Lv; Xiaomei Zhu; Masayuki Sato

    2012-01-01

    The pulsed high-voltage discharge is a new advanced oxidation technology for water treatment.Methyl Orange (MO) dye wastewater was chosen as the target object.Some investigations were conducted on MO decoloration including the discharge characteristics of the multi-needle reactor,parameter optimization,and the degradation mechanism.The following results were obtained.The color group of the azo dye MO was effectively decomposed by water surface plasma.The decoloration rate was promoted with the increase of treatment time,peak voltage,and pulse frequency.When the initial conductivity was 1700 tS/cm,the decoloration rate was the highest.The optimum distahce between the needle electrodes and the water surface was 1 mm,the distance between the grounding electrode and the water surface was 28 mm,and the number of needle electrodes and spacing between needles were 24 and 7.5 mm,respectively.The decoloration rate of MO was affected by the gas in the reactor and varied in the order oxygen > air> argon > nitrogen,and the energy yield obtained in this investigation was 0.45 g/kWh.

  14. High and low frequency relaxation oscillations in a capacitive discharge plasma

    Institute of Scientific and Technical Information of China (English)

    Zhou Zhu-Wen; Sungjin Kim; Ji Shi-Yin; Sun Guang-Yu; Deng Ming-Sen

    2008-01-01

    Both high and low frequency relaxation oscillations have been observed in an argon capacitive discharge connected to a peripheral grounded chamber through a slot with dielectric spacers.The oscillations,observed from time-varying optical emission of the main discharge chamber,show,for example,a high frequency(46 kHz)relaxation oscillation at 100 mTorr,with an absorbed power near the peripheral breakdown,and a low frequency(2.7-3.7 Hz)oscillation,at a higher absorbed power.The high frequency oscillation is found to ignite a plasma in the slot,but usually not in the periphery.The high frequency oscillation is interpreted by using an electromagnetic model of the slot impedance,combined with the circuit analysis of the system including a matching network.The model is further developed by using a parallel connection of variable peripheral capacitance to analyse the low frequency oscillation.The results obtained from the model are in agreement with the experimental observations and indicate that a variety of behaviours are dependent on the matching conditions.

  15. Genetic effects of an air discharge plasma on Staphylococcus aureus at the gene transcription level

    Science.gov (United States)

    Xu, Zimu; Wei, Jun; Shen, Jie; Liu, Yuan; Ma, Ronghua; Zhang, Zelong; Qian, Shulou; Ma, Jie; Lan, Yan; Zhang, Hao; Zhao, Ying; Xia, Weidong; Sun, Qiang; Cheng, Cheng; Chu, Paul K.

    2015-05-01

    The dynamics of gene expression regulation (at transcription level) in Staphylococcus aureus after different doses of atmospheric-pressure room-temperature air plasma treatments are investigated by monitoring the quantitative real-time polymerase chain reaction. The plasma treatment influences the transcription of genes which are associated with several important bio-molecular processes related to the environmental stress resistance of the bacteria, including oxidative stress response, biofilm formation, antibiotics resistance, and DNA damage protection/repair. The reactive species generated by the plasma discharge in the gas phase and/or induced in the liquid phase may account for these gene expression changes.

  16. Tailoring surface properties of polyethylene separator by low pressure 13.56 MHz RF oxygen plasma glow discharge

    Science.gov (United States)

    Li, Chun; Liang, Chia-Han; Huang, Chun

    2016-01-01

    Low-pressure plasma surface modification in a radio-frequency capacitively coupled glow discharge of oxygen gas was carried out to induce polar functional groups onto polyethylene membrane separator surfaces to enhance its hydrophilicity. The surface changes in surface free energy were monitored by static contact angle measurement. A significant increase in the surface energy of polyethylene membrane separators caused by the oxygen gas plasma modifications was observed. The static water contact angle of the plasma-modified membrane separator significantly decreased with the increase in treatment duration and plasma power. An obvious increase in the surface energy of the membrane separators owing to the oxidative effect of oxygen-gas-plasma modifications was also observed. Optical emission spectroscopy was carried out to analyze the chemical species generated by oxygen gas plasma surface modification. The variations in the surface morphology and chemical structure of the separators were confirmed by scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy (XPS). XPS showed significantly higher surface concentrations of oxygen functional groups in the oxygen-gas-plasma-modified polymeric separator surfaces than in the unmodified polymeric separator surface. The experimental results show the important role of chemical species in the interaction between oxygen gas plasmas and the separator surface, which can be controlled by surface modification to tailor the hydrophilicity of the separator.

  17. Surface modification of acrylate intraocular lenses with dielectric barrier discharge plasma at atmospheric pressure

    Institute of Scientific and Technical Information of China (English)

    WANG Yao; LIU ZhenMei; XU ZhiKang; YAO Ke

    2009-01-01

    Surface modification with dielectric barrier discharge (DBD) plasma was carried out at atmospheric pressure (argon as the discharge gas) to improve the biocompatibility of hydrophobic acrylate intraocular lens (IOL). Changes of the plasma-treated IOL surface in chemical composition,morphology and hydrophilicity were comprehensively evaluated by X-ray photoelectron spectroscopy (XPS),field emission scanning electron microscopy (FESEM),atomic force microscopy (AFM) and water contact angle (WCA) measurements. The surface biocompatibility of the untreated and plasma-treated IOLs was compared with the adhesion behavior of platelets,macrophages and lens epithelial cells (LECs) in vitro. After DBD plasma treatment,the hydrophilicity of the IOL surface was obviously improved. The changes in WCA with treatment extension may be attributed to both the introduction of oxygen or/and nitrogen-containing polar groups and the increase of surface roughness induced by plasma etching effect. The existence of low molecular weight oxidized material (LMWOM) was proved on the plasma treated IOL which was caused by the chain scission effect of the plasma treatment. The plasma-treated lOLs resisted the adhesion of platelets and macrophages significantly. The LECs spreading and proliferation were postponed on the lOLs plasma-treated for more than 180 s,with a well maintained epithelial phenotype of LECs. The IOL biocompatibility was improved after the DBD plasma treatment. We speculate that slighter foreign-body reaction and later incidence of anterior capsule opacification (ACO) may be expected after implantation of the argon DBD plasma-treated IOL.

  18. Surface modification of acrylate intraocular lenses with dielectric barrier discharge plasma at atmospheric pressure

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Surface modification with dielectric barrier discharge(DBD) plasma was carried out at atmospheric pressure(argon as the discharge gas) to improve the biocompatibility of hydrophobic acrylate intraocular lens(IOL).Changes of the plasma-treated IOL surface in chemical composition,morphology and hydrophilicity were comprehensively evaluated by X-ray photoelectron spectroscopy(XPS),field emission scanning electron microscopy(FESEM),atomic force microscopy(AFM) and water contact angle(WCA) measurements.The surface biocompatibility of the untreated and plasma-treated IOLs was compared with the adhesion behavior of platelets,macrophages and lens epithelial cells(LECs) in vitro.After DBD plasma treatment,the hydrophilicity of the IOL surface was obviously improved.The changes in WCA with treatment extension may be attributed to both the introduction of oxygen or/and nitrogen-containing polar groups and the increase of surface roughness induced by plasma etching effect.The existence of low molecular weight oxidized material(LMWOM) was proved on the plasma-treated IOL which was caused by the chain scission effect of the plasma treatment.The plasma-treated IOLs resisted the adhesion of platelets and macrophages significantly.The LECs spreading and proliferation were postponed on the IOLs plasma-treated for more than 180 s,with a well maintained epithelial phenotype of LECs.The IOL biocompatibility was improved after the DBD plasma treatment.We speculate that slighter foreign-body reaction and later incidence of anterior capsule opacification(ACO) may be expected after implantation of the argon DBD plasma-treated IOL.

  19. Topological structures of vortex flow on a flying wing aircraft, controlled by a nanosecond pulse discharge plasma actuator

    Science.gov (United States)

    Du, Hai; Shi, Zhiwei; Cheng, Keming; Wei, Dechen; Li, Zheng; Zhou, Danjie; He, Haibo; Yao, Junkai; He, Chengjun

    2016-06-01

    Vortex control is a thriving research area, particularly in relation to flying wing or delta wing aircraft. This paper presents the topological structures of vortex flow on a flying wing aircraft controlled by a nanosecond plasma dielectric barrier discharge actuator. Experiments, including oil flow visualization and two-dimensional particle image velocimetry (PIV), were conducted in a wind tunnel with a Reynolds number of 0.5 × 106. Both oil and PIV results show that the vortex can be controlled. Oil topological structures on the aircraft surface coincide with spatial PIV flow structures. Both indicate vortex convergence and enhancement when the plasma discharge is switched on, leading to a reduced region of separated flow.

  20. Ignition and dynamics of high-voltage glow discharge plasma implantation

    Science.gov (United States)

    Fu, Ricky K. Y.; Chu, Paul K.; Tian, X. B.; Yang, S. Q.

    2006-01-01

    The self-ignition and dynamics of glow discharge plasma in the pulsed high-voltage plasma immersion ion implantation mode have been investigated. After ignition during the pulse-on period, the glow discharge continues to be sustained for a long period of time after the high-voltage pulse has been turned off as monitored by a Langmuir probe. The glow discharge and ignition lie on the left side of the Paschen curve when pd (gas pressure times electrode separation) is adjusted by using different anode to cathode distances utilizing a conducting grounded grid. The increased or constant implantation current Ia reveals that the ion sheath is stable and conforms to the cathode structure as the plasma density increases by one to two orders of magnitude towards the anode. In addition, the duration of the post-pulse-off plasma can be as long as several times of the pulse duration. The ignition time and duration of the plasma depend on the working pressure, applied voltage and pulse duration.

  1. Influence of plasma discharge on the structure of polytetrafluoroethylene film and step coverage on polymer substrate

    Energy Technology Data Exchange (ETDEWEB)

    Grytsenko, K.P. [Institute of Semiconductor Physics, 45 Nauki pr., Kyiv, 03028 (Ukraine); Institute of Photonics, Laser and Plasma Technology, University of Applied Sciences Wildau, F.-Engels-Str. 63, 15745, Wildau (Germany)], E-mail: d_gryts@isp.kiev.ua; Lytvyn, P.M. [Institute of Semiconductor Physics, 45 Nauki pr., Kyiv, 03028 (Ukraine); Friedrich, J.; Schulze, R.D. [Federal Institute for Materials Research and Testing (BAM), Unter den Eichen 87, 12205 Berlin (Germany); Schrader, S. [Institute of Photonics, Laser and Plasma Technology, University of Applied Sciences Wildau, F.-Engels-Str. 63, 15745, Wildau (Germany)

    2007-09-15

    Polytetrafluoroethylene (PTFE) films have been deposited onto polycarbonate (PC) substrates from the products of PTFE evaporation, activated by a cloud of accelerated electrons. A 40.68 MHz glow discharge was used during the deposition process. The polymer films have been characterised by XPS, FTIR and AFM. The use of the low power plasma during film growth led to the formation of PTFE films with modified structure. Films are amorphous and contain more cross-links, but in general, the structure of their macromolecules is still linear. An increase of RF-power leads to the formation of films with large amount of double bonds and enhanced internal stresses. Deposition of PTFE on PC without plasma treatment led to the formation of PTFE clusters up to 50 nm in diameter. The RMS roughness of the films, deposited without plasma, was about 4 nm, while the films deposited with plasma treatment had a roughness of 1.5 nm. The use of plasma has an additional effect if a PTFE coating is deposited on the PC substrate with submicrometer-sized steps. Without plasma the steps retain a rectangular shape. Deposited with the RF-discharge the PTFE layers resemble plasma-polymerised films. Under certain conditions the deposited films can fill trenches in the substrate like a wetting liquid, while under other conditions they avoid trenches and grow in between them.

  2. Changes in the plasma diazepam concentration and its anticonvulsant effect after the discharge of a diazepam suppository from the rectum in rats.

    Science.gov (United States)

    Hidaka, N; Suemaru, K; Araki, H

    2007-01-01

    One of the clinical problems regarding the use of suppositories for patients is the discharge of the medication itself after the insertion of the suppository. The effects of the discharge of diazepam (DZP) suppositories from the rectum on the plasma DZP concentration and its anticonvulsant action were investigated in rats. The plasma DZP concentration reached a maximum at approx. 30 min after the rectal administration of a 5 mg/kg DZP suppository. The discharge of the DZP suppository from the rectum at 5 or 10 min after rectal administration significantly reduced the plasma DZP concentration and the anticonvulsant action of the DZP suppository against pentylenetetrazol-induced seizures. However, when the suppository was discharged from the rectum after 20 min, the plasma DZP concentration and the anticonvulsant action were only slightly but not significantly decreased. These results suggest that the discharge of the DZP suppository in the early phase, within 20 min, decreases the plasma concentration and the anticonvulsant action of the DZP suppository in rats. Therefore, when the suppository is discharged from the rectum immediately, sufficient observation and proper treatment are necessary.

  3. Radiofrequency antenna for suppression of parasitic discharges in a helicon plasma thruster experiment.

    Science.gov (United States)

    Takahashi, Kazunori

    2012-08-01

    A radiofrequency (rf) antenna for helicon plasma thruster experiments is developed and tested using a permanent magnets helicon plasma source immersed in a vacuum chamber. A magnetic nozzle is provided by permanent magnets arrays and an argon plasma is produced by a 13.56 MHz radiofrequency helicon-wave or inductively-coupled discharge. A parasitic discharge outside the source tube is successfully suppressed by covering the rf antenna with a ceramic ring and a grounded shield; a decrease in the ion saturation current of a Langmuir probe located outside the source tube is observed and the ion saturation current on axis increases simultaneously, compared with the case of a standard uncovered rf antenna. It is also demonstrated that the covered antenna can yield stable operation of the source.

  4. Ignition of beam plasma discharge in the electron beam experiment in space

    Science.gov (United States)

    Sasaki, S.; Kawashima, N.; Kuriki, K.; Yanagisawa, M.; Roberts, W. T.; Taylor, W. W. L.

    1985-01-01

    An ignition of beam plasma discharge (BPD) in space was observed in a neutral gas-electron beam interaction experiment by Space Shuttle/Spacelab-1 in 1983. An electron beam of 8 kV 100 mA was injected into a high dense nitrogen gas cloud of 10 to the 23rd molecules which was released during 100 msec from the Orbiter. The appearance of the beam and its surroundings observed by a low-light-level TV camera showed a local ignition of the beam plasma discharge in the gas cloud. The enhanced plasma production, generation of auroral emission, and associated wave emission were also detected by onboard diagnostic instruments.

  5. Enhancement of ZnO-Based Photocatalyst Activity by RF Discharge-Plasma Treatment*

    Science.gov (United States)

    Savastenko, N. A.; Filatov, I. I.; Lyushkevich, V. A.; Chubrik, N. I.; Gabdullin, M. T.; Ramazanov, T. S.; Abdullin, H. A.; Kalkozova, V. A.

    2016-11-01

    The structure and photocatalytic properties of polydisperse zinc oxide (ZnO) powder treated with a low-pressure radio-frequency (RF) plasma discharge were studied. The photocatalytic properties of ZnO before and after the treatment were studied with respect to photodegradation of organic impurities using decomposition of methyl orange in aqueous solution by UV light as an example. It was found that the photodegradation kinetics were described well by first-order equations. The photodegradation mechanisms of methyl orange over untreated and plasma-treated ZnO samples were different. It was shown that the effectiveness of the photodegradation expressed in terms of reaction constants increased by 20% after RF discharge-plasma treatment of the photocatalyst.

  6. An expression for the h l factor in low-pressure electronegative plasma discharges

    Science.gov (United States)

    Chabert, P.

    2016-04-01

    The positive ion flux exiting a low-pressure plasma discharge is a crucial quantity in global (volume-averaged) models. In discharges containing only electrons and positive ions (electropositive discharges), it is common to write this flux {Γ\\text{wall}}={{h}\\text{l}}{{n}\\text{i0}}{{u}\\text{B}} , where {{n}\\text{i0}} is the central positive ion density, {{u}\\text{B}} is the positive ion fluid speed at the sheath edge (the Bohm speed), and {{h}\\text{l}} is the positive ion edge-to-centre density ratio. There are well established formulae for {{h}\\text{l}} in electropositive discharges, but for discharges containing negative ions (electronegative discharges), the analysis is more complicated. The purpose of this paper is to propose a formula for the {{h}\\text{l}} factor in low-pressure electronegative discharges. We use the numerical solution of fluid equations with Boltzmann negative ions, including Poisson’s equation, as a guide to derive an analytical expression that can easily be incorporated in global models. The parameter space in which the derived expression is valid is discussed at the end of the paper.

  7. Development of a long pulse plasma gun discharge for magnetic turbulence studies

    Science.gov (United States)

    Schaffner, David

    2016-10-01

    A long pulse ( 300 μs) plasma gun discharge is in development at the Bryn Mawr College Plasma Laboratory for the production of sustained magnetized plasma injection for magnetohydrodynamic (MHD) turbulence studies. An array of eight 0.5mF parallel capacitors are used to create a pulse-forming-network (PFN) with a plateaued current output of 50kA for at least 200 of the 300 μs pulse. A 24cm inner diameter plasma gun provides stuffing flux fields at the stuffing threshold in order to allow for the continuous injection of magnetic helicity. Plasma is injected into a 24cm diameter flux-conserving aluminum chamber with a high density port array for fine spatial resolution diagnostic access. Fluctuations of magnetic field and saturation current are measured using pickup probes and Langmuir probes respectively.

  8. A Cascaded Discharge Plasma-Adsorbent Technique for Engine Exhaust Treatment

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A cascaded system of electrical discharges (non-thermal plasma) and adsorptionprocess was investigated for the removal of oxides of Nitrogen (NOx) and total hydrocarbons(THC) from an actual diesel engine exhaust. The non-thermal plasma and adsorption processeswere separately studied first and then the cascaded process was studied. In this study, differenttypes of adsorbents were used. The NOx removal efficiency was higher with plasma-associatedadsorption (cascaded) process compared to the individual processes and the removal efficiencywas found almost invariant in time. When associated by plasma, among the adsorbents studied,activated charcoal and MS-13X were more effective for NOx and THC removal respectively. Theexperiments were conducted at no load and at 50 % load conditions. The plasma reactor was keptat room temperature throughout the experiment, while the temperature of the adsorbent reactorwas varied. A relative comparison of adsorbents was discussed at the end.

  9. A Cascaded Discharge Plasma-Adsorbent Technique for Engine Exhaust Treatment

    Science.gov (United States)

    Rajanikanth, B. S.; Srinivasan, A. D.; Arya, Nandiny B.

    2003-06-01

    A cascaded system of electrical discharges (non-thermal plasma) and adsorption process was investigated for the removal of oxides of Nitrogen (NOx) and total hydrocarbons (THC) from an actual diesel engine exhaust. The non-thermal plasma and adsorption processes were separately studied first and then the cascaded process was studied. In this study, different types of adsorbents were used. The NOx removal efficiency was higher with plasma-associated adsorption (cascaded) process compared to the individual processes and the removal efficiency was found almost invariant in time. When associated by plasma, among the adsorbents studied, activated charcoal and MS-13X were more effective for NOx and THC removal respectively. The experiments were conducted at no load and at 50% load conditions. The plasma reactor was kept at room temperature throughout the experiment, while the temperature of the adsorbent reactor was varied. A relative comparison of adsorbents was discussed at the end.

  10. Measurements of 3D slip velocities and plasma column lengths of a gliding arc discharge

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Jiajian; Gao, Jinlong; Ehn, Andreas; Aldén, Marcus; Li, Zhongshan, E-mail: zhongshan.li@forbrf.lth.se, E-mail: alpers@ma.tum.de [Division of Combustion Physics, Lund University, P.O. Box 118, S-221 00 Lund (Sweden); Moseev, Dmitry [Max-Planck-Institut für Plasmaphysik, D-85748 Garching bei München (Germany); FOM Institute DIFFER, 3430 BE Nieuwegein (Netherlands); Kusano, Yukihiro [Department of Wind Energy, Section for Composites and Materials Mechanics, Technical University of Denmark, Risø Campus, Frederiksborgvej 399, DK-4000 Roskilde (Denmark); Salewski, Mirko [Department of Physics, Section for Plasma Physics and Fusion Energy, Technical University of Denmark, DK-2800 Kongens Lyngby (Denmark); Alpers, Andreas, E-mail: zhongshan.li@forbrf.lth.se, E-mail: alpers@ma.tum.de; Gritzmann, Peter; Schwenk, Martin [Zentrum Mathematik, Technische Universität München, D-85747 Garching bei München (Germany)

    2015-01-26

    A non-thermal gliding arc discharge was generated at atmospheric pressure in an air flow. The dynamics of the plasma column and tracer particles were recorded using two synchronized high-speed cameras. Whereas the data analysis for such systems has previously been performed in 2D (analyzing the single camera image), we provide here a 3D data analysis that includes 3D reconstructions of the plasma column and 3D particle tracking velocimetry based on discrete tomography methods. The 3D analysis, in particular, the determination of the 3D slip velocity between the plasma column and the gas flow, gives more realistic insight into the convection cooling process. Additionally, with the determination of the 3D slip velocity and the 3D length of the plasma column, we give more accurate estimates for the drag force, the electric field strength, the power per unit length, and the radius of the conducting zone of the plasma column.

  11. Dynamic Properties of Helium Atmospheric Dielectric-Barrier-Discharge Plasma Jet.

    Science.gov (United States)

    Uchida, Giichiro; Takenaka, Kosuke; Miyazaki, Atsushi; Kawabata, Kazufumi; Setsuhara, Yuichi

    2015-03-01

    We present here experiments on helium atmospheric dielectric-barrier discharge jet in open air. A long stable plasma plume is realized at high applied voltage and high gas flow rate. Optical emission measurements show that the plasma plume consists of two part: a plume head with high energy electrons and a tail part with low energy electrons. The plasma plume propagates away from the quartz-tube outlet with about 30-80 km/sec along the helium gas flow channel. The propagation velocity of plasma plume is in the time scale of electron drift velocity, and the electric field plays an important role as a driving force of the plasma plume propagation.

  12. Emission characteristics and electron kinetic coefficients of the plasma of a transverse volume discharge initiated in a mixture of heavy inert gases with chlorine molecules

    Science.gov (United States)

    Shuaibov, A. K.; Chygin, V. I.; Shimon, L. L.; Shevera, I. V.; Gorun, P. P.; Obukhovskii, R. O.

    2010-05-01

    The results of studying the radiation due to argon, krypton, and xenon monochloride bands, as well as to the bands of chlorine molecules, from the plasma of a transverse Ar-Kr-Xe-Cl2 volume discharge are reported. The working mixture of a pulse radiation source is optimized with regard to its pressure and elemental composition and parameters of an excitation system. By numerically solving the Boltzmann kinetic equation for the electron energy distribution function, the transport characteristics of plasma electrons and discharge power specific losses are found for different values of the reduced electric field strength. The plasma parameters are simulated for the quaternary mixture, which is most appropriate for a multiwave UV-VUV source. Qualitative analysis is conducted for the most important electron processes in the multicomponent plasma that govern the joint formation of argon, krypton, and xenon monochlorides in the transverse discharge.

  13. Kinetic study on non-thermal volumetric plasma decay in the early afterglow of air discharge generated by a short pulse microwave or laser

    Science.gov (United States)

    Yang, Wei; Zhou, Qianhong; Dong, Zhiwei

    2016-08-01

    This paper reports a kinetic study on non-thermal plasma decay in the early afterglow of air discharge generated by short pulse microwave or laser. A global self-consistent model is based on the particle balance of complex plasma chemistry, electron energy equation, and gas thermal balance equation. Electron-ion Coulomb collision is included in the steady state Boltzmann equation solver to accurately describe the electron mobility and other transport coefficients. The model is used to simulate the afterglow of microsecond to nanosecond pulse microwave discharge in N2, O2, and air, as well as femtosecond laser filament discharge in dry and humid air. The simulated results for electron density decay are in quantitative agreement with the available measured ones. The evolution of plasma decay under an external electric field is also investigated, and the effect of gas heating is considered. The underlying mechanism of plasma density decay is unveiled through the above kinetic modeling.

  14. Controlled cytotoxicity of plasma treated water formulated by open-air hybrid mode discharge

    Science.gov (United States)

    Lu, P.; Boehm, D.; Cullen, P.; Bourke, P.

    2017-06-01

    Plasma treated liquids (PTLs) provide a means to convey a broad range of effects of relevance for food, environmental, or clinical decontamination, plant growth promotion, and therapeutic applications. Devising the reactive species ingredients and controlling the biological response of PTLs are of great interest. We demonstrate an approach by using an open-air hybrid mode discharge (HMD) to control the principal reactive species composition within plasma treated water (PTW), which is then demonstrated to regulate the cytotoxicity of PTW. The cytotoxicity of HMD produced PTW demonstrates a non-monotonic change over the discharge time. Although hydrogen peroxide and nitrite are not the sole effectors for cell death caused by PTW, using them as principal reactive species indicators, cytotoxicity can be removed and/or enhanced by formulating their concentrations and composition through adjusting the discharge mode and time on-line during PTW generation without the addition of additional working gas or chemical scavengers. This work demonstrates that a hybrid mode discharge can be employed to generate a PTW formulation to control a biological response such as cytotoxicity. This provides insights into how plasma treated liquids may be harnessed for biological applications in a specific and controllable manner.

  15. Formation and characteristics of patterns in atmospheric-pressure radio-frequency dielectric barrier discharge plasma

    Science.gov (United States)

    Yang, Lizhen; Liu, Zhongwei; Mao, Zhiguo; Li, Sen; Chen, Qiang

    2017-01-01

    The patterns in radio-frequency dielectric barrier discharge (RF DBD) are studied at atmospheric pressure of argon (Ar) or helium (He) mixed with nitrogen (N2) gas. When a small amount of N2 is mixed with He or Ar gas, discharge patterns are formed. In a N2/He gas mixture, besides the filament discharge that forms patterns, a glow background discharge is also observed, whereas only the filament discharge forms patterns in a N2/Ar gas mixture. The resolution of the hexagonal pattern as a function of applied power and gas flow rate is then explored. On the basis of spatial-temporal images taken using an intensified charge-coupled device (ICCD), we find that there is no interleaving of two transient hexagon sublattices in N2/Ar or N2/He plasma in RF DBD patterns, which are totally different from those in which surface charges dominated in the mid-frequency DBD plasma. This supports our hypothesis that the bulk charges dominate the pattern formation in RF DBD.

  16. Influence of the energy dissipation rate in the discharge of a plasma synthetic jet actuator

    Energy Technology Data Exchange (ETDEWEB)

    Belinger, A; Cambronne, J P [Universite de Toulouse, UPS, INPT, LAPLACE - Laboratoire Plasma et Conversion d' Energie, 118 route de Narbonne, F-31062 Toulouse cedex 9 (France); Hardy, P; Barricau, P; Caruana, D, E-mail: daniel.caruana@onera.fr [ONERA Centre Midi-Pyrenees, Departement Modeles pour l' Aerodynamique et l' Energetique, BP74025, 2 avenue Edouard Belin, 31055 TOULOUSE CEDEX 4 (France)

    2011-09-14

    A promising actuator for high-speed flow control, referred to as a plasma synthetic jet (PSJ), is being studied by the DMAE department of the ONERA, and the Laplace laboratory of the CNRS, in France. This actuator was inspired by the 'sparkjet' device developed by the Johns Hopkins University Applied Physics Laboratory. The PSJ, which produces a synthetic jet with high exhaust velocities, no active mechanical components and no mass flow admission, holds the promise of enabling high-speed flows to be manipulated. With this high-velocity jet it is possible to reduce fluid phenomena such as transition and turbulence, thus making it possible to increase an aircraft's performance whilst at the same time reducing its environmental impact. A thermal plasma discharge was created in a micro-cavity, causing the gas to be expelled. It is relevant that the velocity and momentum depend on the energy dispersed by the electric discharge. To control the frequency and energy dispersed in the plasma, the Laplace laboratory has developed two high-voltage power supply systems. These allow two different types of discharge to be produced, with energy being supplied to the discharge in two different manners. In this paper, we focus on the impact of the power supply on the plasma synthetic jet, and in particular on the role of the rate of energy dissipation in the discharge. In order to estimate the influence of the power supply on the machinery of the actuator, specific experimental techniques were used to investigate the electrical (voltage, current), thermal (Infra-red camera) and aerodynamic (jet duration, isentropic pressure, jet velocity) characteristics. These data sets were used to determine which of the two power supplies was more effective, thus allowing us to reach several conclusions concerning the importance of the energy dissipation rate on the PSJ actuator.

  17. Investigation of Meltblown Microfiber and Electrospun Nanofiber Fabrics Treated with a One Atmosphere Uniform Glow Discharge Plasma (OAUGDP)

    Science.gov (United States)

    Chen, Weiwei; Reece Roth, J.; Tsai, Peter P.-Y.

    2003-10-01

    Nanofiber webs are made by the electrospinning (ES) process [1], which uses the repulsive electrostatic force to spin fibers from a polymer solution or melt at room temperature and low energy input. We have developed apparatus at the UT Textiles and Nonwovens Development Center (TANDEC) to produce fabrics with fiber diameters of tens of nanometers. This paper will report data on the distribution function of nanofiber diameters that were taken from digitized SEM images of the electrospun materials. It is also found in the tensile tests that the strength of the electrospun nanofiber fabrics is up to ten times that of the coarser meltblown material. The one atmosphere uniform glow discharge plasma (OAUGDP) developed at the UT Plasma Sciences Laboratory generates a normal glow electrical discharge at one atmosphere. This plasma has been used to treat meltblown and electrospun fabrics, with a resulting increase in surface energy [1]. We recently found that the surface energy of meltblown Nylon could be increased to 70 dynes/cm by five seconds of OAUGDP exposure, and was durable at this level for six months. Our results also show that Nylon and PU nanofiber fabrics can be exposed to the OAUGDP for treatment without significant damage for up to 10 seconds [1], a duration sufficient to produce important effects, including durable wettability. We will describe our progress in improving the properties of nanofiber fabrics using a variety of latest developments in OAUGDP reactor technology, including a new porous electrode that injects gases other than air to generate different active species for plasma treatment. [1] Tsai P. P.-Y., Chen W., Li X. and Roth J.R.: "Improving the Properties of Protective Clothing by Exposing Nanofiber Webs to a One Atmospheric Uniform Glow Discharge Plasma (OAUGDP)", National Science Foundation (NSF) Grantee¡¯s Workshop and Conference, Birmingham, Alabama, Jan. 6-9, 2003.

  18. Thrust Stand Measurements Using Alternative Propellants in the Microwave Assisted Discharge Inductive Plasma Accelerator

    Science.gov (United States)

    Hallock, Ashley K.; Polzin, Kurt A.

    2011-01-01

    Storable propellants (for example water, ammonia, and hydrazine) are attractive for deep space propulsion due to their naturally high density at ambient interplanetary conditions, which obviates the need for a cryogenic/venting system. Water in particular is attractive due to its ease of handling and availability both terrestrially and extra-terrestrially. While many storable propellants are reactive and corrosive, a propulsion scheme where the propellant is insulated from vulnerable (e.g. metallic) sections of the assembly would be well-suited to process these otherwise incompatible propellants. Pulsed inductive plasma thrusters meet this criterion because they can be operated without direct propellant-electrode interaction. During operation of these devices, electrical energy is capacitively stored and then discharged through an inductive coil creating a time-varying current in the coil that interacts with a plasma covering the face of the coil to induce a plasma current. Propellant is accelerated and expelled at a high exhaust velocity (O(10-100 km/s)) by the Lorentz body force arising from the interaction of the magnetic field and the induced plasma current. While this class of thruster mitigates the life-limiting issues associated with electrode erosion, many pulsed inductive plasma thrusters require high pulse energies to inductively ionize propellant. The Microwave Assisted Discharge Inductive Plasma Accelerator (MAD-IPA) is a pulsed inductive plasma thruster that addressees this issue by partially ionizing propellant inside a conical inductive coil before the main current pulse via an electron cyclotron resonance (ECR) discharge. The ECR plasma is produced using microwaves and a static magnetic field from a set of permanent magnets arranged to create a thin resonance region along the inner surface of the coil, restricting plasma formation, and in turn current sheet formation, to a region where the magnetic coupling between the plasma and the theta

  19. Discharge regime of non-ambipolarity with a self-induced steady-state magnetic field in plasma sources with localized radio-frequency power deposition

    Energy Technology Data Exchange (ETDEWEB)

    Shivarova, A., E-mail: ashiva@phys.uni-sofia.bg; Lishev, St.; Todorov, D.; Paunska, Ts. [Faculty of Physics, Sofia University, BG-1164 Sofia (Bulgaria)

    2015-10-15

    Involving the idea for the Biermann effect known from space physics as well as recent discussions on non-ambipolarity of the electron and ion fluxes in low-pressure discharges, the study builds the discharge pattern in a source with localized RF power deposition outside the region of high electron density. A vortex dc current flowing in an RF discharge and a steady-state magnetic field induced by this current govern the discharge behavior. Owing to a shift in the positions of the electron-density and plasma-potential maxima, the dc current is driven with the purpose of keeping the conservativity of the dc field in the discharge. The results present the spatial structure of a discharge in a regime of non-ambipolarity of the electron and ion fluxes, including its modifications by the magnetic field.

  20. The Effect of Dielectric Barrier Discharge Plasma Treatment on the Microorganisms Found in Raw Cow’s Milk

    OpenAIRE

    Aslan, Yakup

    2016-01-01

    Milk is an essential source of nutrition especially for the breastfed infants. Sterilization of milk is necessary because it can be contaminated by microorganisms due to unhygienic collection and storage conditions. In this study, the sterilization of raw cow milk was performed by using dielectric barrier discharge (DBD) plasma method. Raw milk was transferred to the plasma reactor and dielectric barrier discharge cold plasma was performed by changing various parameters including voltage, exp...

  1. Note: Rapid reduction of graphene oxide paper by glow discharge plasma

    Energy Technology Data Exchange (ETDEWEB)

    Bo, Zheng; Qian, Jiajing; Duan, Liangping; Qiu, Kunzan, E-mail: qiukz@zju.edu.cn; Yan, Jianhua; Cen, Kefa [State Key Laboratory of Clean Energy Utilization, College of Energy Engineering, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Han, Zhao Jun [CSIRO Manufacturing Flagship, P.O. Box 218, Bradfield Road, Lindfield, New South Wales 2070 (Australia); Ostrikov, Kostya [CSIRO Manufacturing Flagship, P.O. Box 218, Bradfield Road, Lindfield, New South Wales 2070 (Australia); Institute for Future Environments and School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, Queensland 4000 (Australia)

    2015-05-15

    This note reports on a novel method for the rapid reduction of graphene oxide (GO) paper using a glow discharge plasma reactor. Glow discharge is produced and sustained between two parallel-plate graphite electrodes at a pressure of 240 mTorr. By exposing GO paper at the junction of negative-glow and Faraday-dark area for 4 min, the oxygen-containing groups can be effectively removed (C/O ratio increases from 2.6 to 7.9), while the material integrality and flexibility are kept well. Electrochemical measurements demonstrate that the as-obtained reduced GO paper can be potentially used for supercapacitor application.

  2. Optical Emission Spectroscopy Investigation of a Surface Dielectric Barrier Discharge Plasma Aerodynamic Actuator

    Institute of Scientific and Technical Information of China (English)

    LI Ying-Hong; WU Yun; JIA Min; ZHOU Zhang-Wen; GUO Zhi-Gang; PU Yi-Kang

    2008-01-01

    The optical emission spectroscopy of a surface dielectric barrier discharge plasma aerodynamic actuator is investigated with different electrode configurations, applied voltages and driving frequencies. The rotational temperature of N2 (C3IIu) molecule is calculated according to its rotational emission band near 380.5 nm. The average electron energy of the discharge is evaluated by emission intensity ratio of first negative system to second positive system of N2. The rotational temperature is sensitive to the inner space of an electrode pair. The average electron energy shows insensitivity to the applied voltage, the driving frequency and the electrode configuration.

  3. Treatment of Candida albicans biofilms with low-temperature plasma induced by dielectric barrier discharge and atmospheric pressure plasma jet

    Energy Technology Data Exchange (ETDEWEB)

    Koban, Ina; Welk, Alexander; Meisel, Peter; Holtfreter, Birte; Kocher, Thomas [Unit of Periodontology, Dental School, University of Greifswald, Rotgerberstr. 8, 17475 Greifswald (Germany); Matthes, Rutger; Huebner, Nils-Olaf; Kramer, Axel [Institute for Hygiene and Environmental Medicine, University of Greifswald, Walther-Rathenau-Str. 49 a, 17487 Greifswald (Germany); Sietmann, Rabea [Institute of Microbiology, University of Greifswald, Friedrich-Ludwig-Jahn-Str. 15, 17487 Greifswald (Germany); Kindel, Eckhard; Weltmann, Klaus-Dieter, E-mail: ina.koban@uni-greifswald.d [Leibniz Institute for Plasma Science and Technology (INP), Felix-Hausdorff-Str. 2, 17489 Greifswald (Germany)

    2010-07-15

    Because of some disadvantages of chemical disinfection in dental practice (especially denture cleaning), we investigated the effects of physical methods on Candida albicans biofilms. For this purpose, the antifungal efficacy of three different low-temperature plasma devices (an atmospheric pressure plasma jet and two different dielectric barrier discharges (DBDs)) on Candida albicans biofilms grown on titanium discs in vitro was investigated. As positive treatment controls, we used 0.1% chlorhexidine digluconate (CHX) and 0.6% sodium hypochlorite (NaOCl). The corresponding gas streams without plasma ignition served as negative treatment controls. The efficacy of the plasma treatment was determined evaluating the number of colony-forming units (CFU) recovered from titanium discs. The plasma treatment reduced the CFU significantly compared to chemical disinfectants. While 10 min CHX or NaOCl exposure led to a CFU log{sub 10} reduction factor of 1.5, the log{sub 10} reduction factor of DBD plasma was up to 5. In conclusion, the use of low-temperature plasma is a promising physical alternative to chemical antiseptics for dental practice.

  4. Production characteristics of reactive oxygen/nitrogen species in water using atmospheric pressure discharge plasmas

    Science.gov (United States)

    Takahashi, Kazuhiro; Satoh, Kohki; Itoh, Hidenori; Kawaguchi, Hideki; Timoshkin, Igor; Given, Martin; MacGregor, Scott

    2016-07-01

    A pulsed discharge, a DC corona discharge, and a plasma jet are separately generated above a water surface, and reactive oxygen species and reactive nitrogen species (ROS/RNS) in the water are investigated. ROS/RNS in water after the sparging of the off-gas of a packed-bed dielectric barrier discharge (PB-DBD) are also investigated. H2O2, NO2 -, and NO3 - are detected after plasma exposure and only NO3 - after off-gas sparging. Short-lifetime species in plasma are found to play an important role in H2O2 and NO2 - production and long-lifetime species in NO3 - production. NO x may inhibit H2O2 production through OH consumption to produce HNO2 and HNO3. O3 does not contribute to ROS/RNS production. The pulsed plasma exposure is found to be effective for the production of H2O2 and NO2 -, and the off-gas sparging of the PB-DBD for the production of NO3 -.

  5. UNJUK KERJA REAKTOR PLASMA DIELECTRIC BARRIER DISCHARGE UNTUK PRODUKSI BIODIESEL DARI MINYAK KELAPA SAWIT

    Directory of Open Access Journals (Sweden)

    Ardian Dwi Yudhistira

    2013-10-01

    Full Text Available Biodiesel is one of alternative renewable energy source to substitute diesel fuel. Various biodiesel productionprocesses through transesterification reaction with a variety of catalysts have been developed by previousresearcher. This process still has the disadvantage of a long reaction time, and high energy need. DielectricBarrier Discharge (DBD plasma electro-catalysis may become a solution to overcome the drawbacks in theconventional transesterification process. This process only needs a short time reaction and low energy process.The purpose of this study was to assess the performance of DBD plasma rector in making biodiesel such as: theeffect of high voltage electric value, electrodes gap, mole ratio of methanol / oil, and reaction time. TheResearch method was using GC-MS (Gas Cromatography-Mass Spectrofotometry and FTIR (FourierTransform Infrared Spectrofotometry and then it will be analysed the change of chemical bond betweenreactant and product. So, the reaction mechanism can be predicted. Biodiesel is produced using methanol andpalm oil as reactants and DBD plasma used as reactor in batch system. Then, reactants contacted by highvoltage electric. From the results of this research can be concluded that the reaction mechanism occurs in theprocess is the reaction mechanism of cracking, the higher of electric voltage and the longer of reaction time leadto increasing of product yield. The more of mole ratio of methanol / oil and widening the gap between theelectrodes lead to decreased product yield. From this research, product yield maksimum is 89,8% in the variableof rasio mol metanol/palm oil 3:1, voltage 10 kV, electrode gap 1,5 cm, and reaction time 30 seconds.

  6. Aerodynamic flow-control with dielectric barrier discharge plasma actuators; Aerodynamische Stroemungssteuerung mittels dielektrischer Barriereentladungs-Plasmaaktuatoren

    Energy Technology Data Exchange (ETDEWEB)

    Wilke, Joern Bastian

    2009-07-01

    In this work, measurements of the spatial-temporal evolution of velocity vector fields, induced by a dielectric barrier discharge plasma actuator, are presented for the first time in order to enhance the understanding of these actuators. A procedure for calculating the body forces-induced by these actuators-from the measured velocity vector fields is also described. A number of parametric studies with plasma actuators, were performed in order to identify the relevant parameter dependencies concerning the effectiveness and the efficiency for an optimization of these actuators. A new phenomenological model for the simulation of the aerodynamic effect of plasma actuators was developed, which can be used to produce more accurate numerical results than existing models. The suitability of plasma actuators in aerodynamic applications was investigated for two different cases. In the first case, a circulation control of a rotorcraft airfoil by plasma actuators, the actuators were arranged such that the gurney flap active principle was achieved and observed for the first time. In the second case, a plasma actuator was mounted on the leading edge of a delta wing to successfully demonstrate flow control up to Re=10{sup 6}. The three velocity components in the plane normal to the flow velocity were measured, enabling the analysis of the change of the leading edge vortices due to plasma actuation. (orig.)

  7. Influence of dielectric materials on uniformity of large-area capacitively coupled plasmas for N2/Ar discharges

    Science.gov (United States)

    Liang, Ying-Shuang; Zhang, Yu-Ru; Wang, You-Nian

    2016-10-01

    The effect of the dielectric ring on the plasma radial uniformity is numerically investigated in the practical 450-mm capacitively coupled plasma reactor by a two-dimensional self-consistent fluid model. The simulations were performed for N2/Ar discharges at the pressure of 300 Pa, and the frequency of 13.56 MHz. In the practical plasma treatment process, the wafer is always surrounded by a dielectric ring, which is less studied. In this paper, the plasma characteristics are systematically investigated by changing the properties of the dielectric ring, i.e., the relative permittivity, the thickness and the length. The results indicate that the plasma parameters strongly depend on the properties of the dielectric ring. As the ratio of the thickness to the relative permittivity of the dielectric ring increases, the electric field at the wafer edge becomes weaker due to the stronger surface charging effect. This gives rise to the lower ion density, flux and N atom density at the wafer edge. Thus the homogeneous plasma density is obtained by selecting optimal dielectric ring relative permittivity and thickness. In addition, we also find that the length of the dielectric ring should be as short as possible to avoid the discontinuity of the dielectric materials, and thus obtain the large area uniform plasma. Project supported by the National Natural Science Foundation of China (Grant Nos. 11335004 and 11405019) and the Important National Science and Technology Specific Project of China (Grant No. 2011ZX02403-001).

  8. Rapid removal of bacterial endotoxin and natural organic matter in water by dielectric barrier discharge plasma: Efficiency and toxicity assessment.

    Science.gov (United States)

    Zhang, Can; Fang, Zhendong; Liu, Wenjun; Tian, Fang; Bai, Miao

    2016-11-15

    Low-temperature plasma was used to control bacteria, endotoxins and natural organic matter (NOM) in water by a dielectric barrier discharge (DBD) device. Results indicate that DBD plasma has an obvious inactivation effect on various bacteria in water. The degree of inactivation from difficult to easy is as follows: Bacillus subtilis>Escherichia coli>Staphylococcus aureus. Activated ultrapure water treated using DBD plasma exhibited a sustained sterilization effect, but this sterilization effect decreased gradually after 1h. The total-endotoxin (free-endotoxin and bound-endotoxin) released by Escherichia coli during inactivation, as well as artificially simulated endotoxin in a control solution, was significantly controlled by DBD plasma. Both the metabolites that appeared after inactivation of microorganisms by plasma treatment, and the NOM in filtration effluent of a water treatment plant were well removed by DBD plasma if the treatment duration was sufficiently long. However, the acute toxicity increased significantly, and persisted for at least 2h, indicating that some long-life active substances were generated during the DBD process. Therefore, the removal of bacteria, endotoxins or NOM does not mean a safe water is produced. It is also important to eliminate the toxicity and byproducts produced during water treatment for the continuous promotion and industrial application of DBD plasma.

  9. The use of electrostatic probes to characterize the discharge plasma structure and identify discharge cathode erosion mechanisms in ring-cusp ion thrusters

    Science.gov (United States)

    Herman, Daniel Andrew

    The erosion of the discharge cathode assembly (DCA) is currently one of the lifetime limiting factors of ion thruster operation and will play an even more important role for more ambitious, future ion thruster applications requiring more throughput at higher-power. Erosion of the DCA has been observed throughout the ground-based wear testing of the 30-cm NSTAR ion thruster. Energetic ions have been detected near the DCA, from Laser-Induced Fluorescence (LIF) measurements, that appear to be the cause of the DCA erosion, though a mechanism by which ions gain sufficient energy to sputter erode the DCA material has not been determined. This dissertation presents research aimed at characterizing the discharge chamber plasma near the DCA to determine the mechanism by which energetic ions are created and erode the DCA inside ring-cusp ion engines. A diagnostic technique is developed to interrogate the near-DCA regions of two ion thrusters: the 30-cm FMT2 NSTAR and 40-cm LM4 NEXT engines. Both engines contain similar plasma structures. Number densities are highest along cathode centerline as the axial magnetic field near the DCA effectively confines electrons to a narrow plume. Plasma potential mappings rule out the existence of a potential-hill that has been proposed as the cause of the DCA erosion. A free standing potential gradient structure is found to form the transition between the low-potential cathode plume and the high-potential bulk discharge plasma, termed a double layer. The field-aligned double layer accelerates ions from the bulk discharge plasma towards the DCA centerline. Measured plasma parameters and LIF velocimetry data are used to calculate an erosion rate utilizing near-threshold sputtering yield formulae. Singly-ionized xenon cannot solely account for the observed NSTAR erosion rates. Incorporation of double-ionized xenon from measured double-to-single current measurements in the plume of the 30-cm and 40-cm thrusters significantly increases the

  10. A tomographic visualization of electric discharge sound fields in atmospheric pressure plasma using laser diffraction

    Science.gov (United States)

    Nakamiya, Toshiyuki; Mitsugi, Fumiaki; Iwasaki, Yoichiro; Ikegami, Tomoaki; Tsuda, Ryoichi; Sonoda, Yoshito; Danuta Stryczewska, Henryka

    2013-02-01

    The phase modulation of transparent gas can be detected using Fraunhofer diffraction technique, which we call optical wave microphone (OWM). The OWM is suitable for the detection of sonic wave from audible sound to ultrasonic wave. Because this technique has no influence on sound field or electric field during the measurement, we have applied it to the sound detection for the electric discharges. There is almost no research paper that uses the discharge sound to examine the electrical discharge phenomenon. Two-dimensional visualization of the sound field using the OWM is also possible when the computerized tomography (CT) is combined. In this work, coplanar dielectric barrier discharge sin different gases of Ar, N2, He were characterized via the OWM as well as applied voltage and discharge current. This is the first report to investigate the influence of the type of the atmospheric gas on the two-dimensional sound field distribution for the coplanar dielectric barrier discharge using the OWM with CT. Contribution to the Topical Issue "13th International Symposium on High Pressure Low Temperature Plasma Chemistry (Hakone XIII)", Edited by Nicolas Gherardi, Henryca Danuta Stryczewska and Yvan Ségui.

  11. Preparation of carbon nanoparticles by plasma arc discharge under fluidized dynamic equilibrium

    Science.gov (United States)

    Wang, F.; Sun, D. L.; Hong, R. Y.; Kumar, M. R.

    2016-06-01

    Continuous preparation of carbon nanoparticles by dielectric barrier discharge (DBD)-induced non-thermal plasma arc discharge with large spacing in a modified fluidized bed is presented. Discharge arc is generated via the inducement of DBD which provides conductive media in order to realize a large spacing arc discharge. Three kinds of flow conditions defined as full circulation, fluidized dynamic equilibrium, and full collection are determined by the relationship of critical fluidized velocity and the real gas velocity after some modification of the fluidized bed. Movement model of carbon nanoparticles has been proposed to illustrate the flow conditions. A visualized and comprehensive refinement of aggregating processes has been exhibited and proved by high-resolution transmission electron microscopy. Simplified equivalent electrical conductive model of the arc discharge system is successful to generally and perspicuously figure out the discharge process which is impeded by the generated carbon nanoparticles. Effects of flow conditions and flow ratio of carrier gas/carbon source on morphology and yield of nanoparticles have been analyzed by morphology observation and yield calculation along with modeling the process.

  12. Plasma diagnostics and modeling of direct current microplasma discharges at atmospheric pressure

    Science.gov (United States)

    Wang, Qiang

    High pressure (100s of torr) microplasma (length scale 100s of micrometer) non-equilibrium discharges have potential applications as chemical microreactors, sensors, microelectromechanical systems (MEMS), and excimer radiation sources. Experimental and theoretical studies of these microplasmas can provide critical information on fundamental discharge characteristics, and help extend the window of stable discharge operation. Spatially resolved measurements (resolution ˜ 6 mum) were taken across a 200 mum slot-type microdischarge in atmospheric pressure helium or argon. Small amounts of actinometer gases were added to the flow for optical emission spectroscopy measurements. Gas temperature profiles were determined from N2 emission rotational spectroscopy. Stark splitting of the hydrogen Balmer-beta (Hbeta ) line was used to investigate the electric field distribution in the cathode sheath region. Electron densities were evaluated from the analysis of the spectral line broadenings of Hbeta emission. The measured gas temperature was in the range of 350--650 K in He, and 600--1200 K in Ar, both peaking near the cathode and increasing with power. The electron density in the bulk plasma was in the range (3-7)x1013 cm -3 in He, and (1-4)x1014 cm-3 in Ar. The measured electric field in He peaked at the cathode and decayed to small values over a distance of ˜50 mum (sheath edge) from the cathode. The experimental data were also used to validate a self-consistent one-dimensional plasma model. By a combination of measurements and simulation it was found that the dominant gas heating mechanism in DC microplasmas was ion Joule heating. Simulation results also predicted the existence of electric field reversals in the negative glow under operating conditions that favor a high electron diffusion flux emanating from the cathode sheath. The electric field adjusted to satisfy continuity of the total current. Also, the electric field in the anode layer was self adjusted to be

  13. Low-pressure hydrogen discharge maintenance in a large-size plasma source with localized high radio-frequency power deposition

    Energy Technology Data Exchange (ETDEWEB)

    Todorov, D.; Shivarova, A., E-mail: ashiva@phys.uni-sofia.bg; Paunska, Ts. [Faculty of Physics, Sofia University, BG-1164 Sofia (Bulgaria); Tarnev, Kh. [Department of Applied Physics, Technical University-Sofia, BG-1000 Sofia (Bulgaria)

    2015-03-15

    The development of the two-dimensional fluid-plasma model of a low-pressure hydrogen discharge, presented in the study, is regarding description of the plasma maintenance in a discharge vessel with the configuration of the SPIDER source. The SPIDER source, planned for the neutral-beam-injection plasma-heating system of ITER, is with localized high RF power deposition to its eight drivers (cylindrical-coil inductive discharges) and a large-area second chamber, common for all the drivers. The continuity equations for the charged particles (electrons and the three types of positive ions) and for the neutral species (atoms and molecules), their momentum equations, the energy balance equations for electrons, atoms and molecules and the Poisson equations are involved in the discharge description. In addition to the local processes in the plasma volume, the surface processes of particle reflection and conversion on the walls as well as for a heat exchange with the walls are included in the model. The analysis of the results stresses on the role of the fluxes (particle and energy fluxes) in the formation of the discharge structure. The conclusion is that the discharge behavior is completely obeyed to non-locality. The latter is displayed by: (i) maximum values of plasma parameters (charged particle densities and temperatures of the neutral species) outside the region of the RF power deposition, (ii) shifted maxima of the electron density and temperature, of the plasma potential and of the electron production, (iii) an electron flux, with a vortex structure, strongly exceeding the total ion flux which gives evidence of a discharge regime of non-ambipolarity and (iv) a spatial distribution of the densities of the neutral species resulting from their fluxes.

  14. Application of Non-Thermal Plasma to the Treatment of Effluent Discharged Into River Choumlou in Bafoussam, West Cameroon

    Directory of Open Access Journals (Sweden)

    Estella T. Njoyim

    2016-07-01

    Full Text Available Most rivers in urban areas of developing countries are the of effluents discharged from industries. This is the case of River Choumlou (in Bafoussam-West Region, Cameroon which receives all discharges from “Brasseries du Cameroun”, Bafoussam branch. The objective of this work was to determine the level of organic contaminants in water samples and to treat the polluted samples using the non-thermal gliding arc plasma. Nonthermal plasma consists of charged particles, radicals and excited molecules. The aim was to show the interest of such a process for cleaning up of surface waters (real effluent and to cope with the protection of our environment. Due to the fact that pollution of streams and rivers from the discharge of sewage and industrial wastes poses a major problem to the environment, the researchers were particularly interested in investigating the oxidizing and acidifying properties of non-thermal plasma on polluted surface water. Samples were collected upstream and downstream from the brewery’s effluent outlet. Samples taken at the point R1 (downstream were first analyzed by volumetric and instrumental methods in order to determine the organoleptic, physico-chemical and organic parameters. These samples were then exposed to the gliding discharge in humid air for a time period of between 3-30 minutes. After 30 minutes of exposure, a decrease in turbidity (24.09%, BOD5 (44.93% and COD (48.92% were observed resulting in transparency apparition; with a decrease in pH (7.9 to 3 due to the formation of acidifying species in solution. These results reflect a considerable reduction in the pollution load of the water collected at R1. This work shows that the effectiveness of the Gliding Arc in wastewater treatment is attributed to the oxidizing power of the hydroxyl radical and acidifying power of the nitrogen monoxide radical formed in the plasma. Despite the low rate of reduction of COD and BOD5 in 30 min, it can be said that the plasma

  15. Stimulated Electromagnetic Emission Indicator of Glow Plasma Discharges from Ionospheric HF Wave Transmissions with HAARP

    Science.gov (United States)

    Bernhardt, P. A.; Scales, W.; Briczinski, S. J.; Fu, H.; Mahmoudian, A.; Samimi, A.

    2012-12-01

    High power radio waves resonantly interact with to accelerate electrons for production of artificial aurora and plasma clouds. These plasma clouds are formed when the HF frequency is tuned near a harmonic of the electron cyclotron frequency. At a narrow band resonance, large electrostatic fields are produced below the F-layer and the neutral atmosphere breaks down with a glow plasma discharge. The conditions for this resonance are given by matching the pump wave frequency and wave-number with the sum of daughter frequencies and wave-numbers for several plasma modes. The most likely plasma mode that accelerates the electrons is the electron Bernstein wave in conjunction with an ion acoustic wave. Both upper hybrid and whistler mode waves are also possible sources of electron acceleration. To determine the plasma process for electron acceleration, stimulated electromagnetic emissions are measured using ground receivers in a north-south chain from the HAARP site. Recent observations have shown that broad band spectral lines downshifted from the HF pump frequency are observed when artificial plasma clouds are formed. For HF transmissions are the 2nd, 3rd, and 4th gyro harmonic, the downshifted indicators are found 500 Hz, 20 kHz, and 140 kHz, respectively, from the pump frequency. This Indicator Mode (IM) anticipates that a plasma layer will be formed before it is recorded with an ionosonde or optical imager.

  16. Three dimensional complex plasma structures in a combined radio frequency and direct current discharge

    CERN Document Server

    Mitic, S; Khrapak, S A; Morfill, G E; 10.1063/1.4798418

    2013-01-01

    We report on the first detailed analysis of large three dimensional (3D) complex plasma structures in experiments performed in pure rf and combined rf+dc discharge modes. Inductively coupled plasma (ICP) is generated by an rf coil wrapped around the vertically positioned cylindrical glass tube at a pressure of 0.3 mbar. In addition, dc plasma can be generated by applying voltage to the electrodes at the ends of the tube far from the rf coil. The injected monodisperse particles are levitated in the plasma below the coil. A scanning laser sheet and a high resolution camera are used to determine the 3D positions of about $10^5$ particles. The observed bowl-shaped particle clouds reveal coexistence of various structures, including well-distinguished solid-like, less ordered liquid-like, and pronounced string-like phases. New criteria to identify string-like structures are proposed.

  17. Potential of electric discharge plasma methods in abatement of volatile organic compounds originating from the food industry.

    Science.gov (United States)

    Preis, S; Klauson, D; Gregor, A

    2013-01-15

    Increased volatile organic compounds emissions and commensurate tightening of applicable legislation mean that the development and application of effective, cost-efficient abatement methods are areas of growing concern. This paper reviews the last two decades' publications on organic vapour emissions from food processing, their sources, impacts and treatment methods. An overview of the latest developments in conventional air treatment methods is presented, followed by the main focus of the paper, non-thermal plasma technology. The results of the review suggest that non-thermal plasma technology, in its pulsed corona discharge configuration, is an emerging treatment method with potential for low-cost, effective abatement of a wide spectrum of organic air pollutants. It is found that the combination of plasma treatment with catalysis is a development trend that demonstrates considerable potential. The as yet relatively small number of plasma treatment applications is considered to be due to the novelty of pulsed electric discharge techniques and a lack of reliable pulse generators and reactors. Other issues acting as barriers to widespread adoption of the technique include the possible formation of stable oxidation by-products, residual ozone and nitrogen oxides, and sensitivity towards air humidity.

  18. Single-Crystal MgO Hollow Nanospheres Formed in RF Impulse Discharge Plasmas

    Directory of Open Access Journals (Sweden)

    Satoru Iizuka

    2012-01-01

    Full Text Available Spherical MgO nanoparticles with a hollow inside, that is, MgO hollow nanospheres, were created in Ar/O2 plasma produced by radio frequency (RF impulse discharge using a Mg rod electrode. The hollow nanospheres were found on the SiO2 plates placed near the powered Mg electrode. The electron refraction pattern showed that each nanosphere was made of a single crystal of MgO. Since the shape was spherical, these nanoparticles seemed to be created during the levitation in the plasma without touching any walls. The formation mechanism with a quasiliquid cooling model was also discussed.

  19. Study of fast capillary discharge plasma columns for soft x-ray amplifiers

    Science.gov (United States)

    Rocca, Jorge J. G.; Cortazar, O. D.; Szapiro, Benito T.; Tomasel, Fernando G.; Hartshorn, D.

    1994-02-01

    The efficient generation, by a fast discharge, of capillary plasma channels containing Ne-like and Ni-like ions for collisionally excited soft-x-ray lasers is reported. Rapid pulse excitation of capillary channels 1.5 mm in diameter with currents of less than 70 kA produced Ca and Ti plasmas in which atoms are ionized up to the F-like state. Line emission at the wavelengths corresponding to the 3p - 3s and 3d - 3p transitions of Ne-like Ca has been observed.

  20. Ionic Wind Phenomenon and Charge Carrier Mobility in Very High Density Argon Corona Discharge Plasma

    Science.gov (United States)

    Nur, M.; Bonifaci, N.; Denat, A.

    2014-04-01

    Wind ions phenomenon has been observed in the high density argon corona discharge plasma. Corona discharge plasma was produced by point to plane electrodes and high voltage DC. Light emission from the recombination process was observed visually. The light emission proper follow the electric field lines that occur between point and plane electrodes. By using saturation current, the mobilities of non-thermal electrons and ions have been obtained in argon gas and liquid with variation of density from 2,5 1021 to 2 1022 cm-3. In the case of ions, we found that the behaviour of the apparent mobility inversely proportional to the density or follow the Langevin variation law. For non-thermal electron, mobility decreases and approximately follows a variation of Langevin type until the density <= 0,25 the critical density of argon.

  1. Plasma Treatment of Polyethylene Powder Particles in Hollow Cathode Glow Discharge

    Science.gov (United States)

    Wolter, Matthias; Quitzau, Meike; Bornholdt, Sven; Kersten, Holger

    2008-09-01

    Polyethylen (PE) is widely used in the production of foils, insulators, packaging materials, plastic bottles etc. Untreated PE is hydrophobic due to its unpolar surface. Therefore, it is hard to print or glue PE and the surface has to be modified before converting. In the present experiments a hollow cathode glow discharge is used as plasma source which is mounted in a spiral conveyor in order to ensure a combines transport of PE powder particles. With this set-up a homogeneous surface treatment of the powder is possible while passing the glow discharge. The plasma treatment causes a remarkable enhancement of the hydrophilicity of the PE powder which can be verified by contact angle measurements and X-ray photoelectron spectroscopy.

  2. Numerical study of capacitive coupled HBr/Cl2 plasma discharge for dry etch applications

    Science.gov (United States)

    Gul, Banat; Ahmad, Iftikhar; Zia, Gulfam; Aman-ur-Rehman

    2016-09-01

    HBr/Cl2 plasma discharge is investigated to study the etchant chemistry of this discharge by using the self-consistent fluid model. A comprehensive set of gas phase reactions (83 reactions) including primary processes such as excitation, dissociation, and ionization are considered in the model along with 24 species. Our findings illustrate that the densities of neutral species (i.e., Br, HCl, Cl, H, and H2) produced in the reactor are higher than charged species (i.e., Cl2+, Cl-, HBr+, and Cl+). Density profile of neutral and charged species followed bell shaped and double humped distributions, respectively. Increasing Cl2 fraction in the feedback gases (HBr/Cl2 from 90/10 to 10/90) promoted the production of Cl, Cl+, and Cl2+ in the plasma, indicating that chemical etching pathway may be preferred at high Cl-environment. These findings pave the way towards controlling/optimizing the Si-etching process.

  3. Extended dielectric relaxation scheme for fluid transport simulations of high density plasma discharges

    Science.gov (United States)

    Kwon, Deuk-Chul; Song, Mi-Young; Yoon, Jung-Sik

    2014-10-01

    It is well known that the dielectric relaxation scheme (DRS) can efficiently overcome the limitation on the simulation time step for fluid transport simulations of high density plasma discharges. By imitating a realistic and physical shielding process of electric field perturbation, the DRS overcomes the dielectric limitation on time step. However, the electric field was obtained with assuming the drift-diffusion approximation. Although the drift-diffusion expressions are good approximations for both the electrons and ions at high pressure, the inertial term cannot be neglected in the ion momentum equation for low pressure. Therefore, in this work, we developed the extended DRS by introducing an effective electric field. To compare the extended DRS with the previous method, two-dimensional fluid simulations for inductively coupled plasma discharges were performed. This work was supported by the Industrial Strategic Technology Development Program (10041637, Development of Dry Etch System for 10 nm class SADP Process) funded by the Ministry of Knowledge Economy (MKE, Korea).

  4. Inactivation of Bacteria in Oil Field Injected Water by a Pulsed Plasma Discharge Process

    Science.gov (United States)

    Xin, Qing; Li, Zhongjian; Lei, Lecheng; Yang, Bin

    2016-09-01

    Pulsed plasma discharge was employed to inactivate bacteria in the injection water for an oil field. The effects of water conductivity and initial concentration of bacteria on elimination efficiency were investigated in the batch and continuous flow modes. It was demonstrated that Fe2+ contained in injection water could enhance the elimination efficiency greatly. The addition of reducing agent glutathione (GSH) indicated that active radicals generated by pulsed plasma discharges played an important role in the inactivation of bacteria. Moreover, it was found that the microbial inactivation process for both batch and continuous flow mode well fitted the model based on the Weibull's survival function. supported by Zhejiang Province Welfare Technology Applied Research Project of China (No. 2014C31137), National Natural Science Foundation of China (Nos. 21436007 and U1462201), and the Fundamental Research Funds for the Central Universities of China (No. 2015QNA4032)

  5. A compact, low cost Marx bank for generating capillary discharge plasmas

    Science.gov (United States)

    Dyson, A. E.; Thornton, C.; Hooker, S. M.

    2016-09-01

    We describe in detail a low power Compact Marx Bank (CMB) circuit that can provide 20 kV, 500 A pulses of approximately 100-200 ns duration. One application is the generation of capillary discharge plasmas of density ≈1018 cm-3 used in laser plasma accelerators. The CMB is triggered with a high speed solid state switch and gives a high voltage output pulse with a ns scale rise time into a 50 Ω load (coaxial cable) with run at shot repetition rates of ≳1 Hz. This low power requirement means that the circuit can easily be powered by a small lead acid battery and, therefore, can be floated relative to laboratory earth. The CMB is readily scalable and pulses >45 kV are demonstrated in air discharges.

  6. GeV Electron Beams from a Capillary Discharge Guided Laser Plasma Accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Kei; Gonsalves, Anthony; Panasenko, Dmitriy; Lin, Chen; Toth, Csaba; Geddes, Cameron; Schroeder, Carl; Esarey, Eric; Leemans, Wim

    2010-07-08

    Laser plasma acceleration (LPA) up to 1 GeV has been realized at Lawrence Berkeley National Laboratory by using a capillary discharge waveguide. In this paper, the capillary discharge guided LPA system including a broadband single-shot electron spectrometer is described. The spectrometer was designed specifically for LPA experiments and has amomentumacceptance of 0.01 - 1.1 GeV/c with a percent level resolution. Experiments using a 33 mm long, 300 mu m diameter capillary demonstrated the generation of high energy electron beams up to 1 GeV. By de-tuning discharge delay from optimum guiding performance, selftrapping and acceleration were found to be stabilized producing 460 MeV electron beams.

  7. The evidence of cathodic micro-discharges during plasma electrolytic oxidation process

    Energy Technology Data Exchange (ETDEWEB)

    Nominé, A., E-mail: alexandre.nomine@univ-lorraine.fr [Institut Jean Lamour, UMR 7198 CNRS, Université de Lorraine, Parc de Saurupt, 54011 Nancy (France); National Institute of Science and Technology “MISiS,” 4, Leninskij Prospekt, Moscow 119049 (Russian Federation); Martin, J.; Noël, C.; Henrion, G.; Belmonte, T. [Institut Jean Lamour, UMR 7198 CNRS, Université de Lorraine, Parc de Saurupt, 54011 Nancy (France); Bardin, I. V.; Kovalev, V. L.; Rakoch, A. G. [National Institute of Science and Technology “MISiS,” 4, Leninskij Prospekt, Moscow 119049 (Russian Federation)

    2014-02-24

    Plasma electrolytic oxidation (PEO) processing of EV31 magnesium alloy has been carried out in fluoride containing electrolyte under bipolar pulse current regime. Unusual PEO cathodic micro-discharges have been observed and investigated. It is shown that the cathodic micro-discharges exhibit a collective intermittent behavior, which is discussed in terms of charge accumulations at the layer/electrolyte and layer/metal interfaces. Optical emission spectroscopy is used to determine the electron density (typ. 10{sup 15} cm{sup −3}) and the electron temperature (typ. 7500 K) while the role of F{sup −} anions on the appearance of cathodic micro-discharges is pointed out.

  8. Dielectric barrier discharges: progress on plasma sources and on the understanding of regimes and single filaments

    Science.gov (United States)

    Brandenburg, Ronny

    2017-05-01

    Dielectric barrier discharges (DBDs) are plasmas generated in configurations with an insulating (dielectric) material between the electrodes which is responsible for a self-pulsing operation. DBDs are a typical example of nonthermal atmospheric or normal pressure gas discharges. Initially used for the generation of ozone, they have opened up many other fields of application. Therefore DBDs are a relevant tool in current plasma technology as well as an object for fundamental studies. Another motivation for further research is the fact that so-called partial discharges in insulated high voltage systems are special types of DBDs. The breakdown processes, the formation of structures, and the role of surface processes are currently under investigation. This review is intended to give an update to the already existing literature on DBDs considering the research and development within the last two decades. The main principles and different modes of discharge generation are summarized. A collection of known as well as special electrode configurations and reactor designs will be presented. This shall demonstrate the different and broad possibilities, but also the similarities and common aspects of devices for different fields of applications explored within the last years. The main part is devoted to the progress on the investigation of different aspects of breakdown and plasma formation with the focus on single filaments or microdischarges. This includes a summary of the current knowledge on the electrical characterization of filamentary DBDs. In particular, the recent new insights on the elementary volume and surface memory mechanisms in these discharges will be discussed. An outlook for the forthcoming challenges on research and development will be given.

  9. OPTIMISATION OF DIELECTRIC BARRIER DISCHARGE PLASMA ACTUATORS AND THEIR APPLICATION TO FLUID DYNAMICS

    OpenAIRE

    Erfani, Rasool

    2012-01-01

    The standard dielectric barrier discharge (DBD) plasma actuator, in which an asymmetric arrangement of electrodes leads to momentum coupling into the surrounding air, has already demonstrated its capability for flow control. The effect of some parameters such as dielectric thickness, dielectric temperature, voltage amplitude, driving frequency, different configurations and arrangements on actuator performance are examined. The new configuration of DBD which uses multiple encapsulated electrod...

  10. Effect of a floating circular aperture on a dc glow discharge dusty plasma

    Science.gov (United States)

    Heinrich, Jonathon R.; Kim, Su-Hyun; Merlino, Robert L.

    2009-11-01

    We have investigated novel effects observed when a floating aperture, either 6 mm or 8 mm in diameter, is placed 1-2 cm in front of an anode disk (4 cm diameter) that is used to form a dc glow discharge dusty plasma. Dust is incorporated into the anode glow plasma from a tray located below the anode which contained kaolin powder. The glow discharge traps particles with an average size of 1 micron. When the aperture is placed in front of the disk, well-defined pear-shaped or spherical dust clouds are formed, depending on the diameter of the aperture and its distance from the anode. The dust interacts with the aperture through the potential structure associated with the floating (negative) plate in which the aperture is located. The dust cloud is imaged using a CCD camera and a thin sheet of 532 nm laser light. Some of the effects observed include: outwardly expanding spherical dust acoustic waves and shocks, dust rotation around a void formed at the aperture, and a dust/discharge instability in which the discharge is periodically quenched and reignited while the dust cloud expands and contracts, with the dust retaining a residual charge.

  11. Conversion of natural gas to C2 hydrocarbons through dielectric-barrier discharge plasma catalysis

    Institute of Scientific and Technical Information of China (English)

    王保伟; 许根慧

    2002-01-01

    The experiments are carried out in the system of continuous flow reactors with dielectric-barrier discharge (DBD) for studies on the conversion of natural gas to C2 hydrocarbons through plasma catalysis under the atmosphere pressure and room temperature. The influence of discharge frequency, structure of electrode, discharge voltage, number of electrode, ratio of H2/CH4, flow rate and catalyst on conversion of methane and selectivity of C2 hydrocarbons are investigated. At the same time, the reaction process is investigated. Higher conversion of methane and selectivity of C2 hydrocarbons are achieved and deposited carbons are eliminated by proper choice of parameters. The appropriate operation parameters in dielectric-barrier discharge plasma field are that the supply voltage is 20-40 kV (8.4-40 W), the frequency of power supply is 20 kHz, the structure of (b) electrode is suitable, and the flow of methane is 20-60 ml · min-1. The conversion of methane can reach 45%, the selectivity of C2 hydrocarbons i

  12. Non-Uniform Plasma Discharges in Near Earth Space Environment and Ionosphere to Troposphere Responses

    Science.gov (United States)

    McCanney, J. M.

    2009-05-01

    Most earth weather and ionosphere-space environment coupling studies separate the problems into distinct groups. Heliosphere to solar wind - solar storm activity to ionospheric coupling - thermosphere and mid- altitude to the ionosphere and electrical effects such as elves and sprites and thunderstorms in another group - additionally mid and high latitude weather systems are many times separated also. The theoretical work here shows that not only are these areas coupled and related, but it also shows that without the constant electrical and resulting magnetic driving forces from space environments, earth would have little if no weather variability at all below the ionosphere. With only solar light energy as input, earth (and the other planets) would have little weather at all. The realization that extensive electrical activates occur in and above the troposphere, extending to the ionosphere and ultimately coupling to the magnetosphere have raised the theoretical and experimental questions regarding the sources of EMF which create the observed effects. The current work has identified 17 Local Electrical Batteries (LEBs), which provide the electrical EMF that can be linked to the observed effects the jet streams and lower atmospheric weather phenomenon. The path of the sources of EMF can be followed from the passing solar wind through "tunnels" that end in electrical currents that pass into the atmosphere via the ionosphere to storm cloud systems in the lower atmosphere. However the source of energy comes from localized plasma discharging of a non-uniform plasma environment that powers the electrical systems of the entire solar system. These are ultimately the sources of electrical energy that power the severe lower atmospheric storm systems such as westerly moving hurricanes at low latitudes and associated tornadoes. The connection is made theoretically with the solar wind that drives the 17 identified LEBs. The ultimate source of driving energy is the result of an

  13. Investigation of multifractal nature of floating potential fluctuations obtained from a dc glow discharge magnetized plasma

    Science.gov (United States)

    Shaw, Pankaj Kumar; Saha, Debajyoti; Ghosh, Sabuj; Janaki, M. S.; Iyengar, A. N. Sekar

    2017-03-01

    In this paper, multifractal detrended fluctuation analysis (MF-DFA) has been used to analyze the floating potential fluctuations obtained with a Langmuir probe from a dc glow discharge magnetized plasma device. The generalized Hurst exponents (h(q)) , local fluctuation function (Fq(s)) , the Rényi exponents (τ(q)) and the multifractal spectrum F(α) have been calculated by applying the MF-DFA method. The result of the MF-DFA shows the multifractal nature of these fluctuations. We have investigated the influence of magnetic field on the multifractal nature of the fluctuations and it is seen that degree of multifractality is reduced with the increase in the magnetic field strength. The values of h(q) have been restricted between 0.7 and 1 for the magnetized fluctuations. This result is evidence of the existence of long-range correlations in the fluctuations. Furthermore, we employed shuffle and surrogate approaches to analyze the origins of multifractality. Comparing the MF-DFA results for the data set to those for shuffled and surrogate series, we have found that its multifractal nature is due to the existence of significant long-term correlation.

  14. One-equation modeling and validation of dielectric barrier discharge plasma actuator thrust

    Science.gov (United States)

    Yoon, Jae-San; Han, Jae-Hung

    2014-10-01

    Dielectric barrier discharge (DBD) plasma actuators with an asymmetric electrode configuration can generate a wall-bounded jet without mechanical moving parts, which require considerable modifications of existing aeronautical objects and which incur high maintenance costs. Despite this potential, one factor preventing the wider application of such actuators is the lack of a reliable actuator model. It is difficult to develop such a model because calculating the ion-electric field and fluid interaction consume a high amount calculation effort during the numerical analysis. Thus, the authors proposed a semi-empirical model which predicted the thrust of plasma actuators with a simple equation. It gave a numeric thrust value, and we implemented the value on a computational fluid dynamics (CFD) solver to describe the two-dimensional flow field induced by the actuator. However, the model had a narrow validation range, depending on the empirical formula, and it did not fully consider environment variables. This study presents an improved model by replacing the empirical formulae in the previous model with physical equations that take into account physical phenomena and environmental variables. During this process, additional operation parameters, such as pressure, temperature and ac waveforms, are newly taken to predict the thrust performance of the actuators with a wider range of existing parameters, the thickness of the dielectric barrier, the exposed electrode, the dielectric constant, the ac frequency and the voltage amplitude. Thrust prediction curves from the model are compared to those of earlier experimental results, showing that the average error is less than 5% for more than one hundred instances of data. As in the earlier work, the predicted thrust value is implemented on a CFD solver, and two-dimensional wall-jet velocity profiles induced by the actuator are compared to the previous experimental results.

  15. Space charge, plasma potential and electric field distributions in HiPIMS discharges of varying configuration

    Science.gov (United States)

    Liebig, B.; Bradley, J. W.

    2013-08-01

    An electron-emitting (emissive) probe has been used to study the temporal and spatial distribution of the plasma potential during high-power impulse magnetron sputtering (HiPIMS) discharges with various substrate and magnetic field configurations. The average power was 700 W, with a repetition frequency of 100 Hz and pulse duration of 100 µs. Strongly negative plasma potentials exceeding -300 V and electric fields up to 10 kV m-1, caused by strong separation of charges with net charge carrier densities Δn of about 1014 m-3, were observed during the ignition of the discharge. The spatial distribution of the plasma potential in the stable stage of the discharge showed values consistently 5 V more negative for a floating substrate compared with a grounded one, so enhancing electron transport around the insulated substrate to grounded walls. However, this change in the electrical configuration of the plasma does not alter significantly the fraction of ionized sputtered particles (of about 30%) that can potentially reach the substrate. By changing the degree of unbalance of the sputtering source, we find a strong correlation between the electric field strength in the magnetic trap (created through charge separation) and the absolute value (and shape) of the magnetic field. For the more unbalanced magnetron, a flattening of the plasma potential structure (decrease in the axial electric field) was observed close to the target. Our findings show in principle that manipulation of the potential barrier close to the target through changing the magnetic field can regulate the proportion of sputtered and ionized species reaching the substrate.

  16. INPROVING OF THE QUALITY FOOD FOR ANIMALS BY PULSED POWER PLASMA DISCHARGE

    Directory of Open Access Journals (Sweden)

    Sebastian Gnapowski

    2015-08-01

    Full Text Available Soy beans powder mixed with water is a good food for animals. However, there are two problems with this brew. One is that soy beans powder is sunk down to fast. Parts of soy beans powder are too big and too heavy. Animals do not eat soy beans powder because after a few minutes (around 3min is sunk down and soy beans are on the bottom case. Another negative point is a quick growth of mold, especially during summer when the temperature is highest. Mold is making food unhealthy and causes unpleasant smell. After mold appears it is difficult to clean the case. One of the solutions to eliminate these problems is to use pulse power plasma discharge and the second solution is ultra sound treatment. It was observed that pulse power discharge can decrease the size of soy beans powder a few times. Another advantage of such experiments was that the pulse power discharge killed bacteria and viruses. After our experiments we did not observe mold growing. Using pulse power discharge we can decrease sinking speed by about ten times. Ultra sound generation is useful and can decrease sinking speed even more, compared with pulse power discharge.

  17. On the pulsating electric wind of a Single Dielectric Barrier Discharge (SDBD) plasma actuator

    Science.gov (United States)

    Vernet, Julie; Örlü, Ramis; Alfredsson, P. Henrik

    2014-11-01

    An experimental study is conducted on the electric wind produced by a Single Dielectric Barrier Discharge (SDBD) plasma actuator placed at the top of a half cylinder. Laser Doppler Velocimetry (LDV) measurements were performed and results show that increasing the driving voltage (6-16 kV peak-to-peak) and frequency (0.5-2 kHz) of the actuator increases the induced jet velocity (up to 4 m/s) and thus the momentum added by the actuator. The focus of the present study is on the phase-resolved behavior of the electric wind, in particular, its two strokes. Phase-averaged LDV data reveals that while the velocity during both strokes remains positive, there is nearly a factor of two in amplitude. The difference of behavior between the two strokes and its downstream and wall-normal evolution are mapped for various driving voltages. Results indicate that this difference is restricted to the vicinity of the actuator, thereby justifying the assumption of a steady force in simulations to model the induced force. The study is part of a larger investigation aiming at separation control on the A-pillar of a truck cabin. The support of the Swedish Energy Agency and SCANIA CV of the project Flow Research on Active and Novel Control Efficiency (FRANCE) is greatly acknowledged.

  18. Plasma density enhancement in atmospheric-pressure dielectric-barrier discharges by high-voltage nanosecond pulse in the pulse-on period: a PIC simulation

    Science.gov (United States)

    Sang, Chaofeng; Sun, Jizhong; Wang, Dezhen

    2010-02-01

    A particle-in-cell (PIC) plus Monte Carlo collision simulation is employed to investigate how a sustainable atmospheric pressure single dielectric-barrier discharge responds to a high-voltage nanosecond pulse (HVNP) further applied to the metal electrode. The results show that the HVNP can significantly increase the plasma density in the pulse-on period. The ion-induced secondary electrons can give rise to avalanche ionization in the positive sheath, which widens the discharge region and enhances the plasma density drastically. However, the plasma density stops increasing as the applied pulse lasts over certain time; therefore, lengthening the pulse duration alone cannot improve the discharge efficiency further. Physical reasons for these phenomena are then discussed.

  19. Influences of Excess Oscillation of Voltage Pulse and Discharge Mode on NO Removal Using Barrier-Type Plasma Reactor

    Science.gov (United States)

    Kadowaki, Kazunori; Suzuki, Yoshiaki; Ihori, Haruo; Kitani, Isamu

    This paper presents experimental results of NO removal from a simulated exhausted-gas using a barrier type reactor with screw electrodes subjected to polarity-reversed voltage pulses. The polarity-reversed pulse was produced by direct grounding of a charged coaxial cable because a traveling wave voltage was negatively reflected at the grounding end with a change in its polarity and then it propagated to the plasma reactor at the opposite end. Influence of cable length on NO removal was studied for two kinds of cable connection, single-connected cable and parallel-connected cables. NO removal ratio for a 50m-long cable was lower than that for much shorter cables in both single and parallel connections when the applied voltage became high. Energy efficiency for NO removal also increased with decreasing the cable length. This was because excess discharges during the voltage oscillation caused by the large stored energy in the long cable resulted in reproduction of NO molecules. Energy efficiency was further improved by changing the discharge mode from dielectric barrier discharge (DBD) to surface discharge (SD). Energy efficiency was up to 110g/kWh with 55% NO removal ratio and 34g/kWh with 100% NO removal ratio by using a single 10m-long cable in SD mode.

  20. Observation of plasma jets in a table top plasma focus discharge

    Energy Technology Data Exchange (ETDEWEB)

    Pavez, Cristian; Soto, Leopoldo, E-mail: lsoto@cchen.cl [Comisión Chilena de Energía Nuclear, CCHEN, Casilla 188-D, Santiago (Chile); Center for Research and Applications in Plasma Physics and Pulsed Power, P4, Santiago-Talca (Chile); Departamento de Ciencias Físicas, Facultad de Ciencias Exactas, Universidad Andrés Bello, República 220, Santiago (Chile); Pedreros, José [Comisión Chilena de Energía Nuclear, CCHEN, Casilla 188-D, Santiago (Chile); Departamento de Ingeniería Eléctrica, Universidad de Santiago de Chile, Santiago (Chile); Tarifeño-Saldivia, Ariel [Comisión Chilena de Energía Nuclear, CCHEN, Casilla 188-D, Santiago (Chile); Center for Research and Applications in Plasma Physics and Pulsed Power, P4, Santiago-Talca (Chile)

    2015-04-15

    In the last years, medium size Z-pinch experiments operating at tens of kJ are being used to create supersonic plasma jets. Those experiments are produced with wire arrays and radial foils, and they are conducted in generators based on water-filled transmission lines. Also plasma jets have been observed in small X-pinch experiments operating at 1 kJ. In this work, observations of plasma jets produced in a table top plasma focus device by means of optical and digital interferometry are shown. The device was operated at only ∼70 J, achieving 50 kA in 150 ns. The plasma jets were observed after the pinch, in the region close and on the anode, along the axis. The electron density measured from the jets is in the range 10{sup 24}–10{sup 25 }m{sup −3}. From two consecutive plasma images separated 18 ns, the axial jet velocity was measured in the order of 4 × 10{sup 4 }m/s.

  1. Near Discharge Cathode Assembly Plasma Potential Measurements in a 30-cm NSTAR Type Ion Engine During Beam Extraction

    Science.gov (United States)

    Herman, Daniel A.; Gallimore, Alec D.

    2006-01-01

    Floating emissive probe plasma potential data are presented over a two-dimensional array of locations in the near Discharge Cathode Assembly (DCA) region of a 30-cm diameter ring-cusp ion thruster. Discharge plasma data are presented with beam extraction at throttling conditions comparable to the NASA TH Levels 8, 12, and 15. The operating conditions of the Extended Life Test (ELT) of the Deep Space One (DS1) flight spare ion engine, where anomalous discharge keeper erosion occurred, were TH 8 and TH 12 consequently they are of specific interest in investigating discharge keeper erosion phenomena. The data do not validate the presence of a potential hill plasma structure downstream of the DCA, which has been proposed as a possible erosion mechanism. The data are comparable in magnitude to data taken by other researchers in ring-cusp electron-bombardment ion thrusters. The plasma potential structures are insensitive to thruster throttling level with a minimum as low as 14 V measured at the DCA exit plane and increasing gradually in the axial direction. A sharp increase in plasma potential to the bulk discharge value of 26 to 28 volts, roughly 10 mm radially from DCA centerline, was observed. Plasma potential measurements indicate a low-potential plume structure that is roughly 20 mm in diameter emanating from the discharge cathode that may be attributed to a free-standing plasma double layer.

  2. Control of Reactive Species Generated by Low-frequency Biased Nanosecond Pulse Discharge in Atmospheric Pressure Plasma Effluent

    Science.gov (United States)

    Takashima, Keisuke; Kaneko, Toshiro

    2016-09-01

    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.

  3. Characterization of stationary and pulsed inductively coupled RF discharges for plasma sterilization

    Science.gov (United States)

    Gans, T.; Osiac, M.; O'Connell, D.; Kadetov, V. A.; Czarnetzki, U.; Schwarz-Selinger, T.; Halfmann, H.; Awakowicz, P.

    2005-05-01

    Sterilization of bio-medical materials using radio frequency (RF) excited inductively coupled plasmas (ICPs) has been investigated. A double ICP has been developed and studied for homogenous treatment of three-dimensional objects. Sterilization is achieved through a combination of ultraviolet light, ion bombardment and radical treatment. For temperature sensitive materials, the process temperature is a crucial parameter. Pulsing of the plasma reduces the time average heat strain and also provides additional control of the various sterilization mechanisms. Certain aspects of pulsed plasmas are, however, not yet fully understood. Phase resolved optical emission spectroscopy and time resolved ion energy analysis illustrate that a pulsed ICP ignites capacitively before reaching a stable inductive mode. Time resolved investigations of the post-discharge, after switching off the RF power, show that the plasma boundary sheath in front of a substrate does not fully collapse for the case of hydrogen discharges. This is explained by electron heating through super-elastic collisions with vibrationally excited hydrogen molecules.

  4. Nanosecond pulsed dielectric barrier discharge plasma-catalytic removal of HCHO in humid air

    Science.gov (United States)

    Zhang, Shuai; Wang, Wenchun; Zhang, Li; Zhao, Zilu; Yang, Dezheng

    2017-05-01

    Non-thermal plasma (NTP) has been regarded as a promising method for the removal of a wide range of low concentration volatile organic compounds (VOCs). In this paper, nanosecond pulsed and alternating current dielectric barrier discharge plasmas synergistic catalyst are utilized for removal of formaldehyde (HCHO) in humid air. Working gas is 1% H2O/21% O2/78% N2 with 154 ppm HCHO over total flow rate of 50 mL/min. Specific energy density (SED) are 32.5 JL-1, 35.8 JL-1 and 1069.2 JL-1 at power consumption of 0.325 W, 0.3 W, 8.9 W for removal of 67%, 63.8% and 73.8% HCHO when using bipolar nanosecond pulsed, unipolar nanosecond pulsed and AC dielectric barrier discharge (DBD) plasma, respectively. The removal efficiencies of HCHO using nanosecond pulsed DBD plasma increase approximately 10 20% when the packed-bed Al2O3 pellets exist and can reach up to almost 100% when TiO2 nanoparticles are used while the effect of CeO2 nanoparticles is a bit poor. Analysis indicate that OH radical and O atom play main role for removal HCHO and the gas temperature is a significant factor for its influence on rate constants of HCHO with active particles.

  5. Conversion of natural gas to C2 hydrocarbons through dielectric-barrier discharge plasma catalysis

    Institute of Scientific and Technical Information of China (English)

    王保伟; 许根慧

    2002-01-01

    The experiments are carried out in the system of continuous flow reactors with dielectric-barrier discharge (DBD) for studies on the conversion of natural gas to C2 hydrocarbons through plasma catalysis under the atmosphere pressure and room temperature. The influence of discharge frequency, structure of electrode, discharge voltage, number of electrode, ratio of H2/CH4, flow rate and catalyst on conversion of methane and selectivity of C2 hydrocarbons are investigated. At the same time, the reaction process is investigated. Higher conversion of methane and selectivity of C2 hydrocarbons are achieved and deposited carbons are eliminated by proper choice of parameters. The appropriate operation parameters in dielectric-barrier discharge plasma field are that the supply voltage is 20-40 kV (8.4-40 W), the frequency of power supply is 20 kHz, the structure of (b) electrode is suitable, and the flow of methane is 20-60 mL@min?1. The conversion of methane can reach 45%, the selectivity of C2 hydrocarbons is 76%, and the total selectivity of C2 hydrocarbons and C3 hydrocarbons is nearly 100%. The conversion of methane increases with the increase of voltage and decreases with the flow of methane increase; the selectivity of C2 hydrocarbons decreases with the increase of voltage and increases with the flow of methane increase. The selectivity of C2 hydrocarbons is improved with catalyst for conversion of natural gas to C2 hydrocarbons in plasma field. Methane molecule collision with radicals is mainly responsible for product formation.

  6. Plasma-photocatalyst interaction: Production of oxygen atoms in a low pressure discharge

    Science.gov (United States)

    Guaitella, O.; Gatilova, L.; Rousseau, A.

    2005-04-01

    A pulsed dc low pressure discharge in air (210 Pa) is used to study the mechanisms of activation of a photocatalytic material (TiO2) under plasma exposure. It is first shown that the presence of TiO2 inside the plasma region leads to a strong increase of the reduced electric field. Time resolved measurement of the atomic oxygen density is performed by actinometry during a 10 ms pulse at a low repetition rate (1 Hz) with and without TiO2 pellets inside the plasma region. The presence of TiO2 pellets strongly increases the O atom density during the first millisecond, but this effect saturates for longer exposure times.

  7. INFLUENCE OF VACUUM ARC PLASMA EVAPORATOR CATHODE GEOMETRY OF ON VALUE OF ADMISSIBLE ARC DISCHARGE CURRENT

    Directory of Open Access Journals (Sweden)

    I. A. Ivanou

    2015-01-01

    Full Text Available An analysis of main design parameters that determine a level of droplet formation intensity at the generating stage of plasma flow has been given in the paper. The paper considers the most widely used designs of water cooled consumable cathodes. Ti or Ti–Si and Fe–Cr alloys have been taken as a material for cathodes. The following calculated data: average ionic charge Zi for titanium plasma +1.6; for «titanium–silicon plasma» +1.2, an electronic discharge 1.6022 ⋅ 10–19 C, an ion velocity vi = 2 ⋅ 104 m/s, an effective volt energy equivalent of heat flow diverted in the cathode Uк = 12 V, temperature of erosion cathode surface Тп = 550 К; temperature of the cooled cathode surface То = 350 К have been accepted in order to determine dependence of a maximum admissible arc discharge current on cathode height. The calculations have been carried out for various values of the cathode heights hк (from 0.02 to 0.05 m. Diameter of a target cathode is equal to 0.08 m for a majority of technological plasma devices, therefore, the area of the erosion surface is S = 0.005 m2.A thickness selection for a consumable target cathode part in the vacuum arc plasma source has been justified in the paper. The thickness ensures formation of minimum drop phase in the plasma flow during arc cathode material evaporation. It has been shown that a maximum admissible current of an arc discharge is practically equal to the minimum current of stable arcing when thickness of the consumable cathode part is equal to 0.05 m. The admissible discharge current can be rather significant and ensure high productivity during coating process with formation of relatively low amount of droplet phase in the coating at small values of hк.

  8. NITROGEN POTENTIAL DURING ION NITRIDING PROCESS IN GLOW-DISCHARGE PLASMA

    Directory of Open Access Journals (Sweden)

    A. A. Kozlov

    2015-01-01

    Full Text Available The paper considers problems on regulation of phase composition of a nitrided layer during gas and ion nitriding process in a glow-discharge. It has been established that  available models for control of nitrided layer structure with the help of nitriding index (nitrogen potential can not be applied for nitriding process in the glow-discharge. Principal difference of the ion nitriding from the gas one is in the fact that chemically active nitrogen is formed in the discharge zone (cathode layer and its mass-transfer is carried out in the form of an active particle flow (ions, atoms, molecules which directed to the metal surface.Interrelation of chemical discharge activity with such characteristics of nitriding steel as nitrogen solubility in  α-solid solution and  coefficient diffusion during ion nitriding in low-discharge plasma. It has been shown that regulation of the nitride layer structure during ion nitriding is reached due to changes in nitrogen flow density in plasma. While supporting the flow at the level of nitrogen solubility in  one phase or another (α, γ′  it is possible to obtain the nitrided layer consisting only of α-solid solution or γ′-nitride layer and diffusion sub-layer. Moreover a specific range of nitrogen flow density values exists for every steel grade where it is possible to ensure a limiting nitrogen concentration in α-solid solution and the γ′-layer characterized by low diffusion  mobility is not formed on the surface.

  9. Consequences of unburned hydrocarbons on microstreamer dynamics and chemistry during plasma remediation of NO sub x using dielectric barrier discharges

    CERN Document Server

    Dorai, R

    2003-01-01

    Atmospheric pressure plasmas, and dielectric barrier discharges (DBDs) in particular, are being investigated for their use in the remediation of nitrogen oxides (NO sub x) from automotive exhausts. In their normal mode of operation, DBDs consist of a large density of short-lived filamentary microdischarges. Localized energy deposition results in spatially nonuniform gas temperatures and species densities which initiate advective and diffusive transport. Diesel exhausts, one of the major sources of NO sub x , typically contain unburned hydrocarbons (UHCs) which significantly influence the NO sub x chemistry during plasma remediation. In this paper, we discuss results from a computational investigation of the consequences of UHC chemistry on radial transport dynamics and remediation of NO sub x. In the presence of UHCs, radicals such as O and OH are dominantly consumed in the microstreamer region and their transport to larger radii is reduced. As a result, the conversion of NO to NO sub 2 is mainly restricted t...

  10. Consequences of unburned hydrocarbons on microstreamer dynamics and chemistry during plasma remediation of NOx using dielectric barrier discharges

    Science.gov (United States)

    Dorai, Rajesh; Kushner, Mark J.

    2003-05-01

    Atmospheric pressure plasmas, and dielectric barrier discharges (DBDs) in particular, are being investigated for their use in the remediation of nitrogen oxides (NOx) from automotive exhausts. In their normal mode of operation, DBDs consist of a large density of short-lived filamentary microdischarges. Localized energy deposition results in spatially nonuniform gas temperatures and species densities which initiate advective and diffusive transport. Diesel exhausts, one of the major sources of NOx, typically contain unburned hydrocarbons (UHCs) which significantly influence the NOx chemistry during plasma remediation. In this paper, we discuss results from a computational investigation of the consequences of UHC chemistry on radial transport dynamics and remediation of NOx. In the presence of UHCs, radicals such as O and OH are dominantly consumed in the microstreamer region and their transport to larger radii is reduced. As a result, the conversion of NO to NO2 is mainly restricted to the core of the microstreamer.

  11. Plasma activated dissociation of CO2 studied in a dielectric barrier discharge

    Science.gov (United States)

    Engeln, Richard; Brehmer, Florian; Welzel, Stefan; Klarenaar, Bart; van de Sanden, Richard; Tu/E Collaboration; Afs Gmbh Collaboration; Differ Collaboration

    2014-10-01

    The ever-increasing emission of carbon dioxide into the atmosphere as well as the intermittency problem of electricity produced by renewable energy sources are challenges that urgently need to be addressed. An approach addressing both issues at the same time is converting CO2 to a fuel using plasma driven by electricity from renewable sources. We will present in this contribution the results of a study on the conversion of CO2 to CO in a dielectric barrier discharge in pure CO2 at pressures up to 1000 mbar: FTIR absorption and Raman spectroscopy were applied to measure CO number densities and gas temperatures as function of the specific injected energy. CO densities with a maximum at 1018 cm-3 (mixing ratio of 4.4%) at 46 kJ/sl, energy efficiencies in the range of a few percent and gas temperatures up to 550 K were detected. The CO production is directly linked with the total number of transferred charges q during the residence time tres of CO2 molecules. Also ozone has been detected with a maximum mixing ratio of 0.075%.

  12. Dechlorination and decomposition of chloroform induced by glow discharge plasma in an aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yongjun, E-mail: lyjglow@sohu.com [College of Environmental Science & Engineering, Dalian Maritime University, Dalian 116026 (China); Brook Byers Institute for Sustainable Systems, Georgia Institute of Technology, Atlanta 30332 (United States); Crittenden, John C. [Brook Byers Institute for Sustainable Systems, Georgia Institute of Technology, Atlanta 30332 (United States); Wang, Lei [College of Environmental Science & Engineering, Xiamen University of Technology, Xiamen 361024 (China); Liu, Panliang [Brook Byers Institute for Sustainable Systems, Georgia Institute of Technology, Atlanta 30332 (United States)

    2016-05-05

    Highlights: • Hydrated electrons played an important role for chloroform decomposition. • Oxygen enhanced hydrolyses are critical for the chloroform mineralization. • Energy efficiency of GDP is higher than those of the typical competitive processes. - Abstract: In this study, efficient dechlorination and decomposition of chloroform (CF) induced by glow discharge plasma (GDP) in contact with a sodium sulfate solution was investigated. Intermediate byproducts were determined by ionic chromatography and headspace gas chromatography, respectively. Results showed that CF can be effectively dechlorinated and decomposed under the action of GDP. Both removal and dechlorination of CF increased with increasing pH and with addition of hydroxyl radical scavengers to the solution. Addition of H{sub 2}O{sub 2} to the solution slightly decreased the CF removal. Formic acid, oxalic acid and dichloromethane were determined as the major intermediate byproducts. Final products were carbon dioxide and hydrochloric acid. Hydrated electrons were the most likely active species responsible for initiation of the dechlorination, and hydroxyl radicals may be the ones for the oxidation of the organic intermediate byproducts. Hydrolyses of the chloromethyl radicals contributed much in the mineralization of the organic chlorine. Reaction mechanism was proposed based on the dechlorination kinetics and the distribution of intermediate byproducts.

  13. STUDENT AWARD FINALIST: Oxygen Pathways in Streamer Discharge for Transient Plasma Ignition

    Science.gov (United States)

    Pendleton, S. J.; Bowman, S.; Singleton, D.; Watrous, J.; Carter, C.; Lempert, W.; Gundersen, M. A.

    2011-10-01

    The use of streamers for the ignition of fuels, also known as transient plasma ignition (TPI), has been shown in a variety of engines to improve combustion through decreased ignition delay, increased lean burn capability and increased energy release relative to conventional spark ignition. The mechanisms behind these improvements, however, remain poorly understood. Temperature measurements by optical emission spectroscopy demonstrate that ignition by TPI is a nonthermal process, and thus is almost entirely dependent on the production and presence of electron impact-created active species in the discharge afterglow. Of particular interest are active oxygen species due to their relatively long lifetimes at high pressures and the pivotal role they play in combustion reactions. In order to elucidate the oxygen pathways, here we report the investigation of the temporal evolution of the populations of atomic oxygen and ozone by use of two-photon absorption laser induced fluorescence (TALIF) and UV absorption, respectively. Experimental results are presented and compared to kinetic modeling of the streamers. Future experiments are proposed to better understand the physics behind TPI. Supported by NSF, AFOSR, NumerEx-ONR, AFRL-WPAFB.

  14. Studies of thermal energy confinement scaling in PDX plasmas: D/sup 0/. -->. H/sup +/ limiter discharges

    Energy Technology Data Exchange (ETDEWEB)

    Kaye, S.M.; Goldston, R.J.; Bell, M.; Bol, K.; Bitter, M.; Fonck, R.; Grek, B.; Hawryluk, R.J.; Johnson, D.; Kaita, R.

    1984-06-01

    Experiments were performed on the PDX tokamak to study plasma heating and ..beta.. scaling with higher power, near-perpendicular neutral beam injection. The data taken during these experiments were analyzed using a time-dependent data interpretation code (TRANSP) to study the transport and thermal confinement scaling over a wide range of plasma parameters. This study focuses on results from experiments with D/sup 0/ injection into H/sup +/ plasmas using graphite rail limiters, a = 40 to 44 cm, R = 143 cm, I/sub p/ = 200 to 480 kA, B/sub T/ = 0.7 to 2.2 T, and typically anti n/sub e/ = 2.5 to 4.2 x 10/sup 13/ cm/sup -3/. The results of this study indicate that for both ohmic and neutral beam heated discharges the energy flow out of the plasma is dominated by anomalous electron losses, attributed to electron thermal conduction. The ion conduction losses are well described to electron thermal conduction. The ion conduction losses are well described by neoclassical theory; however, the total ion loss influences the power balance significantly only at high toroidal fields and high plasma currents.

  15. Simulation of electrical discharge in a 3.6 Joule miniature plasma focus device using SIMULINK

    Science.gov (United States)

    Jafari, Hossein; Habibi, Morteza

    2014-08-01

    A novel technique has been developed and studied in this paper to simulate the electrical discharge circuit of a 3.6 J miniature plasma focus device (PFD) and investigate the effect of inductance variation on voltage spike and current dip. The technique is based on a correlation between the electrical discharge circuit and plasma dynamics in a very small PFD that operates at the energy of 3.6 J. The simulation inputs include the charging voltage, capacitor bank capacitance, current limiter resistance, by-pass resistance as well as the time-dependent inductance and resistance of the plasma sheath which are calculated by assuming the plasma dynamics as transit times in going from one phase to the next. The variations of the most important elements in the circuit (i.e. the constant and breakdown inductances) and their effects on the current dip are studied in PFDs with low and high constant inductance. The model demonstrated for achieving a good pinch in the PFD, although the total inductance of the system should be low; however there is always an optimum inductance which causes an appropriate pinch. Furthermore, the electrical power produced by the pulsed power supply, the mechanical energy as well as the magnetic energy which are transferred into the plasma tube were obtained from simulation. The graph of electrical power demonstrated a high instantaneous increment in the power transferred into the plasma as one of the greatest advantages of the pulsed power supply. The simulation was performed using software tools within the MATLAB/SIMULINK simulation environment.

  16. Shock Formation by Plasma Filaments of Microwave Discharge under Atmospheric Pressure

    Science.gov (United States)

    Takahashi, Masayuki; Ohnishi, Naofumi

    2016-03-01

    A one-dimensional compressible fluid calculation was coupled with a finite- difference time-domain code and a particle-in-cell code with collision to reproduce propagation of electromagnetic wave, ionization process of plasma, and shock wave formation in atmospheric microwave discharge. Plasma filaments are driven toward the microwave source at 1 atm, and the distance between each filament is one-fifth of the wavelength of the incident microwave. The strong shock wave is generated due to the high plasma density at the atmospheric pressure. A simple analysis of the microwave propagation into the plasma shows that cut-off density of the microwave becomes smaller with the pressure decrease in a collisional plasma. At the lower pressure, the smaller density plasma is obtained with a diffusive pattern because of the smaller cut-off density and the larger diffusion effect. In contrast with the 1-atm case, the weak shock wave is generated at a rarefied condition, which lowers performance of microwave thruster.

  17. Surface-dependent inactivation of model microorganisms with shielded sliding plasma discharges and applied air flow.

    Science.gov (United States)

    Edelblute, Chelsea M; Malik, Muhammad A; Heller, Loree C

    2015-06-01

    Cold atmospheric plasma inactivates bacteria through reactive species produced from the applied gas. The use of cold plasma clinically has gained recent interest, as the need for alternative or supplementary strategies are necessary for preventing multi-drug resistant infections. The purpose of this study was to evaluate the antibacterial efficacy of a novel shielded sliding discharge based cold plasma reactor operated by nanosecond voltage pulses in atmospheric air on both biotic and inanimate surfaces. Bacterial inactivation was determined by direct quantification of colony forming units. The plasma activated air (afterglow) was bactericidal against Escherichia coli and Staphylococcus epidermidis seeded on culture media, laminate, and linoleum vinyl. In general, E. coli was more susceptible to plasma exposure. A bacterial reduction was observed with the application of air alone on a laminate surface. Whole-cell real-time PCR revealed a decrease in the presence of E. coli genomic DNA on exposed samples. These findings suggest that plasma-induced bacterial inactivation is surface-dependent.

  18. Development of a non-equilibrium 60 MHz plasma jet with a long discharge plume

    Science.gov (United States)

    Uchida, Giichiro; Kawabata, Kazufumi; Ito, Taiki; Takenaka, Kosuke; Setsuhara, Yuichi

    2017-07-01

    High-frequency plasma jets driven by voltages in the frequency range of 6-60 MHz are developed. A long plasma jet, 40 mm in length, is successfully produced by using a pair of ring electrodes outside a quartz tube. The electrode pair consists of a wide power electrode and a narrow ground electrode that is positioned at the head of the tube. The ratio of the length of the ground electrode to the length of the power electrode must be small in order to produce long plasma jets. The high-frequency plasma jet is operated in a non-thermal-equilibrium state at a gas temperature of around 60 °C. Operation at the very-high-frequency of 60 MHz leads to a lower discharge voltage and lower electron energy compared to lower frequencies of 6 and 13.56 MHz. The ability of the very-high-frequency (60 MHz) plasma jet to produce reactive oxygen and nitrogen species in water is also investigated. High H2O2 and NO3- concentrations of more than 1 mmol/l are realized by irradiating 3 ml of deionized water with the plasma for a short period of 2 min.

  19. Space plasma physics results from Spacelab 1

    Science.gov (United States)

    Burch, J. L.

    1985-01-01

    The Spacelab 1 payload carried several instrument systems which together investigated a number of space plasma phenomena. These experiments used the Space Shuttle Orbiter as a platform for making controlled particle-beam, plasma and neutral gas inputs to the ionosphere and magnetosphere and for observing the outputs produced. Spacelab 1 space-plasma investigations included the Space Experiments with Particle Accelerators (SEPAC), Phenomena Induced by Charged Particle Beams (PICPAB), Atmospheric Emissions Photometric Imaging (AEPI) and the Low Energy Electron Spectrometer and Magnetometer. Among the major phenomena investigated both singly and jointly by these experiments are vehicle charging and neutralization, beam-plasma and wave-particle interactions, anomalous ionization phenomena produced by neutral-gas and plasma injections and several phenomena induced by modulated particle beam injections.

  20. Plasma decay in the afterglow of a high-voltage nanosecond discharge in air

    Science.gov (United States)

    Aleksandrov, N. L.; Anokhin, E. M.; Kindysheva, S. V.; Kirpichnikov, A. A.; Kosarev, I. N.; Nudnova, M. M.; Starikovskaya, S. M.; Starikovskii, A. Yu.

    2012-02-01

    The decay of air plasma produced by a high-voltage nanosecond discharge at room temperature and gas pressures in the range of 1-10 Torr was studied experimentally and theoretically. The time dependence of the electron density was measured with a microwave interferometer. The initial electron density was about 1012 cm-3. The discharge homogeneity was monitored using optical methods. The dynamics of the charged particle densities in the discharge afterglow was simulated by numerically solving the balance equations for electron and ions and the equation for the electron temperature. It was shown that, under these experimental conditions, plasma electrons are mainly lost due to dissociative and three-body recombination with ions. Agreement between the measured and calculated electron densities was achieved only when the rate constant of the three-body electron-ion recombination was increased by one order of magnitude and the temperature dependence of this rate constant was modified. This indicates that the mechanism for three-body recombination of molecular ions differs from that of the well-studied mechanism of atomic ion recombination.

  1. Plasma decay in the afterglow of a high-voltage nanosecond discharge in air

    Energy Technology Data Exchange (ETDEWEB)

    Aleksandrov, N. L.; Anokhin, E. M.; Kindysheva, S. V.; Kirpichnikov, A. A.; Kosarev, I. N.; Nudnova, M. M. [Moscow Institute of Physics and Technology (Russian Federation); Starikovskaya, S. M. [Ecole Polytechnique, route de Saclay (France); Starikovskii, A. Yu. [Princeton University (United States)

    2012-02-15

    The decay of air plasma produced by a high-voltage nanosecond discharge at room temperature and gas pressures in the range of 1-10 Torr was studied experimentally and theoretically. The time dependence of the electron density was measured with a microwave interferometer. The initial electron density was about 10{sup 12} cm{sup -3}. The discharge homogeneity was monitored using optical methods. The dynamics of the charged particle densities in the discharge afterglow was simulated by numerically solving the balance equations for electron and ions and the equation for the electron temperature. It was shown that, under these experimental conditions, plasma electrons are mainly lost due to dissociative and three-body recombination with ions. Agreement between the measured and calculated electron densities was achieved only when the rate constant of the three-body electron-ion recombination was increased by one order of magnitude and the temperature dependence of this rate constant was modified. This indicates that the mechanism for three-body recombination of molecular ions differs from that of the well-studied mechanism of atomic ion recombination.

  2. Influence of the Discharge Voltage during Pulse-Plasma Process on the Durability of Edges coated with Superhard Coatings

    Institute of Scientific and Technical Information of China (English)

    Maciej Kupczyk

    2004-01-01

    In the paper the experimental results concerning the functional quality of thin, superhard coatings produced on cutting edges is described. Boron nitride coatings were deposited on insert cutting edges made cemented carbides by the pulse-plasma method. The comparative investigations of mentioned coatings have been concerned of tool life of edges during steel machining. In these investigations for the purpose of additional increase of coated edge durability an interfacial layers were applied. Presented investigations particularly pointed out to essential influence of the values of discharge voltage on the coating structure and durability of edges coated with boron nitride.

  3. Influence of the Discharge Voltage during Pulse-Plasma Process on the Durability of Edges coated with Superhard Coatings

    Institute of Scientific and Technical Information of China (English)

    MaciejKupczyk

    2004-01-01

    In the paper the experimental results concerning the functional quality of thin, superhard coatings produced on cutting edges is described. Boron nitride coatings were deposited on insert cutting edges made cemented carbides by the pulse-plasma method. The comparative investigations of mentioned coatings have been concerned of tool life of edges during steel machining. In these investigations for the purpose of additional increase of coated edge durability an interfacial layers were applied. Presented investigations particularly pointed out to essential influence of the values of discharge voltage on the coating structure and durability of edges coated with boron nitfide.

  4. A model based on equations of kinetics to study nitrogen dioxide behavior within a plasma discharge reactor.

    Science.gov (United States)

    Abedi-Varaki, Mehdi; Ganjovi, Alireza; Shojaei, Fahimeh; Hassani, Zahra

    2015-01-01

    In this work, a zero-dimensional kinetics model is used to study the temporal behavior of different species such as charged particles, radicals and excited states inside a Dielectric Barrier Discharge plasma reactor. It is shown that, the reactor significantly reduces the concentration of nitrogen monoxide as an environmental pollutant. After a drastic increase, a decrease in the concentration of the NO2 molecules inside the reactor is seen. Nitrogen monoxide molecules with a very low concentration are produced inside the reactor and its quick conversion to other products is proved. The obtained results are compared with the existing experimental and simulation findings, whenever possible.

  5. A global plasma model for reactive deposition of compound films by modulated pulsed power magnetron sputtering discharges

    Science.gov (United States)

    Zheng, B. C.; Wu, Z. L.; Wu, B.; Li, Y. G.; Lei, M. K.

    2017-05-01

    A spatially averaged, time-dependent global plasma model has been developed to describe the reactive deposition of a TiAlSiN thin film by modulated pulsed power magnetron sputtering (MPPMS) discharges in Ar/N2 mixture gas, based on the particle balance and the energy balance in the ionization region, and considering the formation and erosion of the compound at the target surface. The modeling results show that, with increasing the N2 partial pressure from 0% to 40% at a constant working pressure of 0.3 Pa, the electron temperature during the strongly ionized period increases from 4 to 7 eV and the effective power transfer coefficient, which represents the power fraction that effectively heats the electrons and maintains the discharge, increases from about 4% to 7%; with increasing the working pressure from 0.1 to 0.7 Pa at a constant N2 partial pressure of 25%, the electron temperature decreases from 10 to 4 eV and the effective power transfer coefficient decreases from 8% to 5%. Using the modeled plasma parameters to evaluate the kinetic energy of arriving ions, the ion-to-neutral flux ratio of deposited species, and the substrate heating, the variations of process parameters that increase these values lead to an enhanced adatom mobility at the target surface and an increased input energy to the substrate, corresponding to the experimental observation of surface roughness reduction, the microstructure transition from the columnar structure to the dense featureless structure, and the enhancement of phase separation. At higher N2 partial pressure or lower working pressure, the modeling results demonstrate an increase in electron temperature, which shifts the discharge balance of Ti species from Ti+ to Ti2+ and results in a higher return fraction of Ti species, corresponding to the higher Al/Ti ratio of deposited films at these conditions. The modeling results are well correlated with the experimental observation of the composition variation and the microstructure

  6. Experimental Study on Surface Dielectric Barrier Discharge Plasma Actuator with Different Encapsulated Electrode Widths for Airflow Control at Atmospheric Pressure

    Science.gov (United States)

    Qi, Xiaohua; Yang, Liang; Yan, Huijie; Jin, Ying; Hua, Yue; Ren, Chunsheng

    2016-10-01

    The surface dielectric barrier discharge (SDBD) plasma actuator has shown great promise as an aerodynamic flow control device. In this paper, the encapsulated electrode width of a SDBD actuator is changed to study the airflow acceleration behavior. The effects of encapsulated electrode width on the actuator performance are experimentally investigated by measuring the dielectric layer surface potential, time-averaged ionic wind velocity and thrust force. Experimental results show that the airflow velocity and thrust force increase with the encapsulated electrode width. The results can be attributed to the distinct plasma distribution at different encapsulated electrode widths. supported by National Natural Science Foundation of China (No. 11175037), National Natural Science Foundation for Young Scientists of China (No. 11305017) and Special Fund for Theoretical Physics (No. 11247239)

  7. Online diagnosis of electron excitation temperature in CH4+H2 discharge plasma at atmospheric pressure by optical emission spectra

    Institute of Scientific and Technical Information of China (English)

    CUI JinHua; XU ZhenFeng; ZHANG JiaLiang; NIE QiuYue; XU GenHui; REN LongLiang

    2008-01-01

    Methane coupling under low temperature plasmas at atmospheric pressure is a green process by use of renewable sources of energy.In this study,CH4+H2 dis-charge plasma was on-line diagnosed by optical emission spectra so as to char-acterize the discharge system and to do spade work for the optimization of the technical parameters for future commercial production of methane coupling under plasmas.The study was focused on a calculation method for the online diagnosis of the electron excitation temperature in CH4+H2 discharge plasma at atmospheric pressure.The diagnostic method is easy,efficient and fairly precise.A serious er-ror in a literature was corrected during the reasoning of its series of equations formerly used to calculate electron temperatures in plasmas.

  8. Polymer Surface Treatment by Atmospheric Pressure Low Temperature Surface Discharge Plasma:Its Characteristics and Comparison with Low Pressure Oxygen Plasma Treatment

    Institute of Scientific and Technical Information of China (English)

    Atsushi KUWABARA; Shin-ichi KURODA; Hitoshi KUBOTA

    2007-01-01

    The polymer treatment with a low-temperature plasma jet generated on the atmospheric pressure surface discharge (SD) plasma is performed.The change of the surface property over time,in comparison with low pressure oxygen (O2) plasma treatment,is examined.As one compares the treatment by atmospheric pressure plasma to that by the low pressure O2 plasma of PS (polystyrene) the treatment effects were almost in complete agreement.However,when the atmospheric pressure plasma was used for PP(polypropylene),it produced remarkable hydrophilic effects.

  9. ULTRAVIOLET INDUCED MOTION OF A FLUORESCENT DUST CLOUD IN AN ARGON DIRECT CURRENT GLOW DISCHARGE PLASMA

    Energy Technology Data Exchange (ETDEWEB)

    Hvasta, M.G.; and Zwicker, A.

    2008-01-01

    Dusty plasmas consist of electrons, ions, neutrals and nm-μm sized particles commonly referred to as dust. In man-made plasmas this dust may represent impurities in a tokamak or plasma etching processing. In astrophysical plasmas this dust forms structures such as planetary rings and comet tails. To study dusty plasma dynamics an experiment was designed in which a 3:1 silica (<5 μm diameter) and fl uorescent dust mixture was added to an argon DC glow discharge plasma and exposed to UV radiation. This fl uorescent lighting technique offers an advantage over laser scattering (which only allows two-dimensional slices of the cloud to be observed) and is simpler than scanning mirror techniques or particle image velocimetry. Under typical parameters (P=150 mTorr, V anode= 100 V, Vcathode= -400 V, Itotal < 2mA) when the cloud is exposed to the UV light (100W, λ = 365 nm) the mixture fl uoresces, moves ~2mm towards the light source and begins rotating in a clockwise manner (as seen from the cathode). By calibrating a UV lamp and adjusting the relative intensity of the UV with a variable transformer it was found that both translational and rotational velocities are a function of UV intensity. Additionally, it was determined that bulk cloud rotation is not seen when the dust tray is not grounded while bulk translation is. This ongoing experiment represents a novel way to control contamination in man-made plasmas and a path to a better understanding of UV-bathed plasma systems in space..

  10. Optical emission spectroscopy of deuterium and helium plasma jets emitted from plasma focus discharges at the PF-1000U facility

    Science.gov (United States)

    Skladnik-Sadowska, E.; Dan'ko, S. A.; Kwiatkowski, R.; Sadowski, M. J.; Zaloga, D. R.; Paduch, M.; Zielinska, E.; Kharrasov, A. M.; Krauz, V. I.

    2016-12-01

    Optical emission spectroscopy techniques were used to investigate the spectra of dense deuterium-plasma jets generated by high-current pulse discharges within the large PF-1000U facility and to estimate parameters of plasma inside the jets and their surroundings. Time-resolved optical spectra were recorded by means of a Mechelle®900 spectrometer. From an analysis of the deuterium line broadening, it was estimated that the electron concentration at a distance 57 cm from the electrode outlets amounted to (0.4-3.7) × 1017 cm-3 depending on the initial gas distribution and the time interval of the spectrum registration after the instant of the plasma jet generation. From the re-absorption dip in the Dβ profile, it was assessed that the electron concentration in the surrounding gas was equal to about 1.5 × 1015 cm-3. On the basis of the measured ratio of He II 468.6 nm and He I 587.6 nm line intensities, it was estimated that the electron temperature amounted to about 5.3 eV. Also estimated were some dimensionless parameters of the investigated plasma jets.

  11. Study of a contracted glow in low-frequency plasma-jet discharges operating with argon

    Energy Technology Data Exchange (ETDEWEB)

    Minotti, F.; Giuliani, L.; Xaubet, M.; Grondona, D. [Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, C1428EHA, Buenos Aires, Argentina and Instituto de Física del Plasma (INFIP), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad de Buenos Aires - UBA, C1428EHA, Buenos Aires (Argentina)

    2015-11-15

    In this work, we present an experimental and theoretical study of a low frequency, atmospheric plasma-jet discharge in argon. The discharge has the characteristics of a contracted glow with a current channel of submillimeter diameter and a relatively high voltage cathode layer. In order to interpret the measurements, we consider the separate modeling of each region of the discharge: main channel and cathode layer, which must then be properly matched together. The main current channel was modeled, extending a previous work, as similar to an arc in which joule heating is balanced by lateral heat conduction, without thermal equilibrium between electrons and heavy species. The cathode layer model, on the other hand, includes the emission of secondary electrons by ion impact and by additional mechanisms, of which we considered emission due to collision of atoms excited at metastable levels, and field-enhanced thermionic emission (Schottky effect). The comparison of model and experiment indicates that the discharge can be effectively sustained in its contracted form by the secondary electrons emitted by collision of excited argon atoms, whereas thermionic emission is by far insufficient to provide the necessary electrons.

  12. Synthesis and characteristics of Ag/Pt bimetallic nanocomposites by arc-discharge solution plasma processing.

    Science.gov (United States)

    Pootawang, Panuphong; Saito, Nagahiro; Takai, Osamu; Lee, Sang-Yul

    2012-10-05

    Arc discharge in solution, generated by applying a high voltage of unipolar pulsed dc to electrodes of Ag and Pt, was used as a method to form Ag/Pt bimetallic nanocomposites via electrode erosion by the effects of the electric arc at the cathode (Ag rod) and the sputtering at the anode (Pt rod). Ag/Pt bimetallic nanocomposites were formed as colloidal particles dispersed in solution via the reduction of hydrogen radicals generated during discharge without the addition of chemical precursor or reducing agent. At a discharge time of 30 s, the fine bimetallic nanoparticles with a mean particle size of approximately 5 nm were observed by transmission electron microscopy (TEM). With increasing discharge time, the bimetallic nanoparticle size tended to increase by forming an agglomeration. The presence of the relatively small amount of Pt dispersed in the Ag matrix could be observed by the analytical mapping mode of energy-dispersive x-ray spectroscopy and high-resolution TEM. This demonstrated that the synthesized particle was in the form of a nanocomposite. No contamination of other chemical substances was detected by x-ray photoelectron spectroscopy. Hence, solution plasma could be a clean and simple process to effectively synthesize Ag/Pt bimetallic nanocomposites and it is expected to be widely applicable in the preparation of several types of nanoparticle.

  13. Catalytic-Dielectric Barrier Discharge Plasma Reactor For Methane and Carbon Dioxide Conversion

    Directory of Open Access Journals (Sweden)

    Istadi Istadi

    2007-10-01

    Full Text Available A catalytic - DBD plasma reactor was designed and developed for co-generation of synthesis gas and C2+ hydrocarbons from methane. A hybrid Artificial Neural Network - Genetic Algorithm (ANN-GA was developed to model, simulate and optimize the reactor. Effects of CH4/CO2 feed ratio, total feed flow rate, discharge voltage and reactor wall temperature on the performance of catalytic DBD plasma reactor was explored. The Pareto optimal solutions and corresponding optimal operating parameters ranges based on multi-objectives can be suggested for catalytic DBD plasma reactor owing to two cases, i.e. simultaneous maximization of CH4 conversion and C2+ selectivity, and H2 selectivity and H2/CO ratio. It can be concluded that the hybrid catalytic DBD plasma reactor is potential for co-generation of synthesis gas and higher hydrocarbons from methane and carbon dioxide and showed better than the conventional fixed bed reactor with respect to CH4 conversion, C2+ yield and H2 selectivity for CO2 OCM process. © 2007 BCREC UNDIP. All rights reserved.[Presented at Symposium and Congress of MKICS 2007, 18-19 April 2007, Semarang, Indonesia][How to Cite: I. Istadi, N.A.S. Amin. (2007. Catalytic-Dielectric Barrier Discharge Plasma Reactor For Methane and Carbon Dioxide Conversion. Bulletin of Chemical Reaction Engineering and Catalysis, 2 (2-3: 37-44.  doi:10.9767/bcrec.2.2-3.8.37-44][How to Link/DOI: http://dx.doi.org/10.9767/bcrec.2.2-3.8.37-44 || or local: http://ejournal.undip.ac.id/index.php/bcrec/article/view/8][Cited by: Scopus 1 |

  14. Experimental Investigation of Flow Separation Control Using Dielectric Barrier Discharge Plasma Actuators

    Institute of Scientific and Technical Information of China (English)

    LI Gang; NIE Chaoqun; LI Yiming; ZHU Junqiang; XU Yanji

    2008-01-01

    Influence of plasma actuators as a flow separation control device was investigated experimentally.Hump model was used to demonstrate the effect of plasma actuators on external flow separation,while for internal flow separation a set of compressor cascade was adopted.In order to investigate the modification of the flow structure by the plasma actuator,the flow field was examined non-intrusively by particle image velocimetry measurements in the hump model experiment and by a hot film probe in the compressor cascade experiment.The results showed that the plasma actuator could be effective in controlling the flow separation both over the hump and in the compressor cascade when the incoming velocity was low.As the incoming velocity increased,the plasma actuator was less effective. It is urgent to enhance the intensity of the plasma actuator for its better application.Methods to increase the intensity of plasma actuator were also studied.

  15. Magnetic Ignition of Pulsed Gas Discharges in Air of Low Pressure in a Coaxial Plasma Gun

    Science.gov (United States)

    Thom, Karlheinz; Norwood, Joseph, Jr.

    1961-01-01

    The effect of an axial magnetic field on the breakdown voltage of a coaxial system of electrodes has been investigated by earlier workers. For low values of gas pressure times electrode spacing, the breakdown voltage is decreased by the application of the magnetic field. The electron cyclotron radius now assumes the role held by the mean free path in nonmagnetic discharges and the breakdown voltage becomes a function of the magnetic flux density. In this paper the dependence of the formative time lag as a function of the magnetic flux density is established and the feasibility of using a magnetic field for igniting high-voltage, high-current discharges is shown through theory and experiment. With a 36 microfarad capacitor bank charged to 48,000 volts, a peak current of 1.3 x 10( exp 6) amperes in a coaxial type of plasma gun was achieved with a current rise time of only 2 microseconds.

  16. Interaction of DC Microhollow Cathode Discharge Plasma Micro Jet with Liquid Media

    Science.gov (United States)

    Zhu, Weidong; Lopez, Jose; Becker, Kurt

    2008-10-01

    There have been different approaches in studying the interaction between plasma and liquid, such as sustained plasmas in contact with liquids and pulsed electric discharge in liquids. Recently, we have discovered that stable plasma can be sustained within a gas cavity maintained inside liquid media. A prototype device with key dimensions in sub-millimeter range were operated successfully in de-ionized water and turbo molecular pump oil with ambient air, pure nitrogen or pure oxygen used as the operating gas. Hydrogen Peroxide production in de-ionized water with ambient air as the working gas is estimated to be about 80 mg/L after 15 minutes plasma jet-water interaction while energy consumption is only about 8-10 W. With the radicals readily generated and directly introduced into the liquid media, it could lead to applications such as in-liquid bio-waste treatment, bio-rich liquid modification, in-situ monitoring/sensing, and filtration of by-products from VOC treatment by plasma.

  17. Plasma centrifuge with vacuum arc discharge applied to the separation of stable isotopes

    Science.gov (United States)

    Delbosco, Edson

    1989-09-01

    The results of a vacuum-arc plasma centrifuge experiment are described. A plasma centrifuge is an apparatus where a plasma column is produced due to the interaction of an electric current with an externally applied magnetic field, vector J x vector B. Among the applications of a rotating plasma, this work deals particularly with its utilization in an isotope enrichment device. The main characteristics of the plasma produced in this experiment are presented, with special attention to the plasma column rotation and the isotope enrichment. The analysis of the results is performed using a fluid model for a completely ionized rigid body rotating plasma column in steady state equilibrium. The main results are: (1) rotation frequency of the plasma column in the range 2 x (exp 4) to 3 x 10 (exp 5) rad/s; (2) enrichment of 10 to 30 pct for the magnesium isotopes, and 290 to 490 pct for the carbon-13 isotope; (3) rigid body rotation of the plasma column only for radii smaller than the characteristic radius of the plasma column, r(sub e); (4) linear dependence of the rotation frequency upon the magnetic field strength only for r is less than r(sub e); (5) existence of an optimum value of the magnetic field for maximum enrichment; and (6) dependence of the rotation frequency upon the inverse of the atomic mass.

  18. Research of the Effects of Electron Focused Electric Field upon an Enhanced Glow Discharge Plasma Ion Implantation

    Institute of Scientific and Technical Information of China (English)

    LI Liu-he; WU Yong-qin; ZHANG Yan-hua; CAI Xun; CHU Paul K

    2004-01-01

    A new Enhanced Glow Discharge Plasma Ion Implantation methods are introduced, in which the plasma are produced by the self glow discharge excitated by high negative voltage bias. The electric field is designed to a electron focusing mode by using a small area hollow anode and a large area sample holder cathode. The pattern of equipotentials of the electric field are calculated through finite-element method. By using the special electron-focusing field, the self glow discharge are enhanced and provide denser ions to implanted into the substrate.

  19. On reabsorption and radiation trapping in homogeneous and inhomogeneous gas discharge plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Golubovskii, Yu B; Timofeev, A [Saint-Petersburg State University, Ulyanovskaya 1, 198504 (Russian Federation); Gorchakov, S; Loffhagen, D; Uhrlandt, D [INP Greifswald, Felix-Hausdorff-Str. 2, D-17489 Greifswald (Germany)

    2011-10-15

    Previous descriptions of the methods of radiation transport are generalized for two cases: small (order of unity) absorption coefficient and large coefficient with inhomogeneous distribution of absorbing atoms. Computation algorithms for the matrices equivalent to the integral operator of the radiation transport are deduced. The methods described are planned for future description of excited and resonance atoms in problems of self-consistent modeling of non-equilibrium plasmas of inert gas. The solution of the transport equation is illustrated by model examples of atom density computation typical for constricted discharge conditions and 'skin-effect' conditions with gas heating taken into account.

  20. Irregular-regular-irregular mixed mode oscillations in a glow discharge plasma

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Sabuj, E-mail: sabuj.ghosh@saha.ac.in; Shaw, Pankaj Kumar, E-mail: pankaj.shaw@saha.ac.in; Saha, Debajyoti, E-mail: debajyoti.saha@saha.ac.in; Janaki, M. S., E-mail: ms.janaki@saha.ac.in; Iyengar, A. N. Sekar, E-mail: ansekar.iyengar@saha.ac.in [Plasma Physics Division, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata-700064 (India)

    2015-05-15

    Floating potential fluctuations of a glow discharge plasma are found to exhibit different kinds of mixed mode oscillations. Power spectrum analysis reveals that with change in the nature of the mixed mode oscillation (MMO), there occurs a transfer of power between the different harmonics and subharmonics. The variation in the chaoticity of different types of mmo was observed with the study of Lyapunov exponents. Estimates of correlation dimension and the Hurst exponent suggest that these MMOs are of low dimensional nature with an anti persistent character. Numerical modeling also reflects the experimentally found transitions between the different MMOs.

  1. Plasma-chemical reactor based on a low-pressure pulsed arc discharge for synthesis of nanopowders

    Science.gov (United States)

    Karpov, I. V.; Ushakov, A. V.; Lepeshev, A. A.; Fedorov, L. Yu.

    2017-01-01

    A reactor for producing nanopowders in the plasma of a low-pressure arc discharge has been developed. As a plasma source, a pulsed cold-cathode arc evaporator has been applied. The design and operating principle of the reactor have been described. Experimental data on how the movement of a gaseous mixture in the reactor influences the properties of nanopowders have been presented.

  2. Noise control of a flow around a cylinder using high-frequency dielectric barrier discharge plasma actuators

    Science.gov (United States)

    Kopiev, V. F.; Belyaev, I. V.; Zaytsev, M. Yu.; Kazansky, P. N.; Kopiev, V. A.; Moralev, I. A.

    2015-03-01

    The effect of high-frequency dielectric barrier discharge plasma actuators on the noise of a flow around a circular cylinder is experimentally studied. It is shown that the plasma actuators are able to reduce the vortex noise of a cylinder within the range of velocities typical for aeroacoustic applications.

  3. Plasma Kinetics in Electrical Discharge in Mixture of Air, Water and Ethanol Vapors for Hydrogen Enriched Syngas Production

    CERN Document Server

    Shchedrin, A I; Ryabtsev, A V; Chernyak, V Ya; Yukhymenko, V V; Olszewski, S V; Naumov, V V; Prysiazhnevych, I V; Solomenko, E V; Demchina, V P; Kudryavtsev, V S

    2008-01-01

    The complex theoretical and experimental investigation of plasma kinetics of the electric discharge in the mixture of air and ethanol-water vapors is carried out. The discharge was burning in the cavity, formed by air jets pumping between electrodes, placed in aqueous ethanol solution. It is found out that the hydrogen yield from the discharge is maximal in the case when ethanol and water in the solution are in equal amounts. It is shown that the hydrogen production increases with the discharge power and reaches the saturation at high value. The concentrations of the main stable gas-phase components, measured experimentally and calculated numerically, agree well in the most cases.

  4. Treatment of Egyptian Maghara coal by plasma ozone synthesized by silent discharge

    CERN Document Server

    Salem, M A; Garamoon, A A; Hassouba, M A

    2003-01-01

    A sample of pyrite rich bituminous coal collected from the main coal seam of Maghara mine, northern sinai, was treated by ozone plasma. The latter was synthesized using silent discharge method (10 kv a.c. and 50 hz). The room temperature Moessbauer spectra of untreated coal sample was easily fitted to two doublet, whose parameters matched those of pyrite (FeS sub 2) and sulfate (FeSO sub 4.H sub 2 O) in addition to hematite. After treatment by ozone plasma, a doublet ascribed to pyrite was observed. The extent of pyrite oxidation to jarosite (Fe sub 2 (SO sub 4) sub 3. nH sub 2 O) was monitored by their relative spectral areas, the incomplete oxidation of pyrite may be attributed to the presence of calcium sulfate layer which acts a screen of ozone.

  5. Extreme Ultraviolet Light Emission from Z-Pinch Discharge Plasma Source

    Science.gov (United States)

    Watanabe, Masato; Song, Inho; Sakamoto, Toshiro; Kobayashi, Yasunori; Okino, Akitoshi; Mohanty, Smruti R.; Horioka, Kazuhiko; Hotta, Eiki

    2006-01-01

    A capillary Z-pinch discharge light source for EUV lithography has been developed. Our device is equipped with a water-cooled ceramic capillary and electrodes, and a solid state pulsed power generator. A stacked static induction thyristors are used as switching elements, which enable high repetition rate operation of pulsed power supply. A magnetic switch is connected in series, which not only assists the semiconductor switch but also provides a preionization current. In the present study, EUV radiation emitted from pinching plasma in a xenon-filled capillary was quantitatively measured using an in-band calorimeter. Time-integrated in-band source image was also observed using a pinhole camera system. Furthermore, new electrode system using plasma jet has been developed.

  6. Indirect determination of the electric field in plasma discharges using laser-induced fluorescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Vaudolon, J., E-mail: julien.vaudolon@cnrs-orleans.fr; Mazouffre, S., E-mail: stephane.mazouffre@cnrs-orleans.fr [CNRS - ICARE (Institut de Combustion Aérothermique Réactivité et Environnement), 1 C Av. de la Recherche Scientifique, 45071 Orléans Cedex 2 (France)

    2014-09-15

    The evaluation of electric fields is of prime interest for the description of plasma characteristics. In this work, different methods for determining the electric field profile in low-pressure discharges using one- and two-dimensional Laser-Induced Fluorescence (LIF) measurements are presented and discussed. The energy conservation, fluid, and kinetic approaches appear to be well-suited for the electric field evaluation in this region of the plasma flow. However, the numerical complexity of a two-dimensional kinetic model is penalizing due to the limited signal-to-noise ratio that can be achieved, making the computation of the electric field subject to large error bars. The ionization contribution which appears in the fluid model makes it unattractive on an experimental viewpoint. The energy conservation and 1D1V kinetic approaches should therefore be preferred for the determination of the electric field when LIF data are used.

  7. Sterilization characteristics of dental instruments using oxygen plasma produced by narrow gap RF discharge

    Science.gov (United States)

    Sakai, Yasuhiro; Liu, Zhen; Goto, Masaaki; Hayashi, Nobuya

    2016-07-01

    Sterilization characteristics and material compatibility of low-pressure RF oxygen plasma sterilization method for dental instruments are investigated. Regarding the characteristics of the plasma sterilizer for dental instruments, it is small and can rapidly sterilize owing to a narrow gap discharge. Sterilization of vial-type biological indicators is achieved for the shortest treatment period of 40 min at an RF power of 80 W at a temperature of 70 °C. At a temperature lower than 60 °C, a sterilization period of 90 min is required using a water-cooled electrode. No surface modifications of dental instruments such as chemical composition and deterioration of fine crystals of a diamond bar were observed under a scanning electron microscope.

  8. Formaldehyde removal from gas streams by means of NaNO2 dielectric barrier discharge plasma.

    Science.gov (United States)

    Liang, Wen-Jun; Li, Jian; Li, Jing-Xin; Zhu, Tao; Jin, Yu-Quan

    2010-03-15

    Destruction of formaldehyde by means of NaNO2 ferro-electric packed bed dielectric barrier discharge plasma in a coaxial cylindrical reactor was carried out at atmospheric pressure and room temperature. The difference among four kinds of NaNO2 ferro-electric reactors was compared in terms of specific energy density (SED), energy yield (EY), and HCHO decomposition. In addition, by-products during the decomposition of HCHO and destruction mechanism were also investigated. The removal efficiency of HCHO increased by means of NaNO2 DBD plasma significantly and enhanced with increasing SED distinctly. More amount of NaNO2 contributed to higher HCHO removal efficiency in the reactors. Reactor C had the highest HCHO removal efficiency among the reactors. As an important by-product, ozone concentration increased with higher SED. The possible main products in the outlet effluent were CO, CO(2) and H(2)O.

  9. Dusty plasma in a glow discharge in helium in temperature range of 5–300 K

    Energy Technology Data Exchange (ETDEWEB)

    Samoilov, I. S.; Baev, V. P.; Timofeev, A. V., E-mail: timofeevalvl@gmail.com; Amirov, R. Kh.; Kirillin, A. V.; Nikolaev, V. S.; Bedran, Z. V. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)

    2017-03-15

    Dusty plasma structures in glow discharge in helium in the temperature range of 5–300 K are investigated experimentally. We have described the experimental setup that makes it possible to continuously vary the temperature regime. The method for experimental data processing has been described. We have measured interparticle distances in the temperature range of 9–295 K and compared them with the Debye radius. We indicate the ranges of variations in experimental parameters in which plasma–dust structures are formed and various types of their behavior are manifested (rotation, vibrations of structures, formation of vertical linear chains, etc.). The applicability of the Yukawa potential to the description of the structural properties of a dusty plasma in the experimental conditions is discussed.

  10. Electron energy distribution functions for modelling the plasma kinetics in dielectric barrier discharges

    Energy Technology Data Exchange (ETDEWEB)

    Carman, R.J. [Department of Physics, Division of Information and Communications Sciences, Macquarie University, Sydney, NSW (Australia)). E-mail: rcarman@physics.mq.edu.au; Mildren, R.P. [Centre for Lasers and Applications, Division of Information and Communications Sciences, Macquarie University, Sydney, NSW (Australia)

    2000-10-07

    In modelling the plasma kinetics in dielectric barrier discharges (DBDs), the electron energy conservation equation is often included in the rate equation analysis (rather than utilizing the local-field approximation) with the assumption that the electron energy distribution function (EEDF) has a Maxwellian profile. We show that adopting a Maxwellian EEDF leads to a serious overestimate of the calculated ionization/excitation rate coefficients and the electron mobility for typical plasma conditions in a xenon DBD. Alternative EEDF profiles are trialed (Druyvesteyn, bi-Maxwellian and bi-Druyvesteyn) and benchmarked against EEDFs obtained from solving the steady-state Boltzmann equation. A bi-Druyvesteyn EEDF is shown to be more inherently accurate for modelling simulations of xenon DBDs. (author)

  11. Nonintrusive microwave diagnostics of collisional plasmas in Hall thrusters and dielectric barrier discharges

    Science.gov (United States)

    Stults, Joshua

    This research presents a numerical framework for diagnosing electron properties in collisional plasmas. Microwave diagnostics achieved a significant level of development during the middle part of the last century due to work in nuclear weapons and fusion plasma research. With the growing use of plasma-based devices in fields as diverse as space propulsion, materials processing and fluid flow control, there is a need for improved, flexible diagnostic techniques suitable for use under the practical constraints imposed by plasma fields generated in a wide variety of aerospace devices. Much of the current diagnostic methodology in the engineering literature is based on analytical diagnostic, or forward, models. The Appleton-Hartree formula is an oft-used analytical relation for the refractive index of a cold, collisional plasma. Most of the assumptions underlying the model are applicable to diagnostics for plasma fields such as those found in Hall Thrusters and dielectric barrier discharge (DBD) plasma actuators. Among the assumptions is uniform material properties, this assumption is relaxed in the present research by introducing a flexible, numerical model of diagnostic wave propagation that can capture the effects of spatial gradients in the plasma state. The numerical approach is chosen for its flexibility in handling future extensions such as multiple spatial dimensions to account for scattering effects when the spatial extent of the plasma is small relative to the probing beam's width, and velocity dependent collision frequency for situations where the constant collision frequency assumption is not justified. The numerical wave propagation model (forward model) is incorporated into a general tomographic reconstruction framework that enables the combination of multiple interferometry measurements. The combined measurements provide a quantitative picture of the spatial variation in the plasma properties. The benefit of combining multiple measurements in a coherent

  12. Application of post-discharge region of atmospheric pressure argon and air plasma jet in the contamination control of Candida albicans biofilms

    Directory of Open Access Journals (Sweden)

    Anelise Cristina Osório Cesar Doria

    Full Text Available Introduction:Candida species are responsible for about 80% of hospital fungal infections. Non-thermal plasmas operated at atmospheric pressure are increasingly used as an alternative to existing antimicrobial strategy. This work investigates the action of post-discharge region of a non-thermal atmospheric plasma jet, generated by a gliding arc reactor, on biofilms of standard strain of Candida albicans grown on polyurethane substrate. Methods Samples were divided into three groups: (i non-treated; (ii treated with argon plasma, and (iii treated with argon plus air plasma. Subsequently to plasma treatment, counting of colony-forming units (CFU/ml and cell viability tests were performed. In addition, the surface morphology of the samples was evaluated by scanning electron microscopy (SEM and optical profilometry (OP. Results Reduction in CFU/ml of 85% and 88.1% were observed in groups ii and iii, respectively. Cell viability after treatment also showed reduction of 33% in group ii and 8% in group iii, in comparison with group i (100%. The SEM images allow observation of the effect of plasma chemistry on biofilm structure, and OP images showed a reduction of its surface roughness, which suggests a possible loss of biofilm mass. Conclusion The treatment in post-discharge region and the chemistries of plasma jet tested in this work were effective in controlling Candida albicans biofilm contamination. Finally, it was evidenced that argon plus air plasma was the most efficient to reduce cell viability.

  13. Manganese-cerium oxide catalysts prepared by non-thermal plasma for NO oxidation: Effect of O2 in discharge atmosphere

    Science.gov (United States)

    Liu, Lu; Zheng, Chenghang; Wu, Shenghao; Gao, Xiang; Ni, Mingjiang; Cen, Kefa

    2017-09-01

    Non-thermal plasma with different O2 concentration in discharge atmosphere was applied to synthesize manganese and cerium mixed-oxides catalysts, which were compared in NO oxidation activity. Discharge atmosphere displayed a crucial influence on the performance of the catalysts prepared by plasma. Relatively low O2 concentration in discharge atmosphere allows synthesizing manganese-cerium oxides catalysts in a moderate environment and therefore is favorable for better physicochemical properties which lead to superior catalytic behavior. The best catalyst was obtained by treatment with 10% O2/N2 plasma and presented over 80% NO conversion in the temperature range of 275-325 °C, whereas catalyst prepared in pure O2 discharge atmosphere had the same activity with a catalyst prepared by calcinations. A correlation between the surface properties of the plasma prepared catalysts and its catalytic activity in NO oxidation is proposed. The amount of the surface adsorbed oxygen has an obvious linear correlation with the amount of Ce3+, the H2 consumption at low temperatures and the catalytic performance. The superior catalytic performance is mainly attributed to the stronger interaction between manganese oxides and ceria, and the formation of poorly crystallized Mn-O-Ce phase in the catalyst which resulted from the slow decomposition of nitrates and organics during plasma treatment. Catalysts prepared in relatively low O2 concentration have large specific surface area and is abundant in Ce3+ species and active oxygen species. The study suggests that plasma treatment with proper discharge gas components is a promising method to prepare effective manganese- cerium oxides catalyst for NO oxidation.

  14. On the self-excitation mechanisms of Plasma Series Resonance oscillations in single- and multi-frequency capacitive discharges

    CERN Document Server

    Schuengel, Edmund; Korolov, Ihor; Derzsi, Aranka; Donko, Zoltan; Schulze, Julian

    2016-01-01

    The self-excitation of plasma series resonance (PSR) oscillations is a prominent feature in the current of low pressure capacitive radio frequency (RF) discharges. This resonance leads to high frequency oscillations of the charge in the sheaths and enhances electron heating. Up to now, the phenomenon has only been observed in asymmetric discharges. There, the nonlinearity in the voltage balance, which is necessary for the self-excitation of resonance oscillations with frequencies above the applied frequencies, is caused predominantly by the quadratic contribution to the charge-voltage relation of the plasma sheaths. Using PIC/MCC simulations of single- and multi- frequency capacitive discharges and an equivalent circuit model, we demonstrate that other mechanisms such as a cubic contribution to the charge-voltage relation of the plasma sheaths and the time dependent bulk electron plasma frequency can cause the self-excitation of PSR oscillations, as well. These mechanisms have been neglected in previous model...

  15. Plasma For-Injector of Separable Material Based on the Beam-Plasma Discharge for Ion-Atomic Separation Technologies. Conception

    OpenAIRE

    Skibenko, E. I.; Yu. V. Kovtun; V.B. Yuferov

    2010-01-01

    In the paper, the functional definition of a plasma for-injector of separable material is presented, and the requirements to it are formulated. The version of a device for the material separation into elements based on the beam-plasma discharge is under consideration. The dimensions of a pilot separating device are determined. The following quantities are estimated: the particle concentration per unit length of the separating device, effective length of the beam-plasma interaction (BPI) withi...

  16. Real time control of long duration plasma discharges in Tore Supra

    Energy Technology Data Exchange (ETDEWEB)

    Saint-Laurent, F.; Bucalossi, J.; Buravand, Y.; Chatelier, E.; Guillerminet, B.; Leroux, F.; Martin, G.; Moulin, D.; Spuig, P.; Van Houtte, D

    2003-07-01

    The in-vessel components and water cooling loops were fully renewed in order to permit Tore-Supra to explore the route of long duration plasma discharges. This renovation has implied important upgrades of both the data acquisition system (DAS) and the plasma control system. This paper is dedicated to these 2 upgrades. The new DAS design allows: -) a continuous data acquisition, -) high data flow rate management (the flow rate can reach 18 MB/s per front-end unit), -) continuous data access and processing, and -) real-time data processing. The upgrade of the plasma control system implies to share information at a real time level. This system is supported by the SCRAMNet network that has proved its flexibility (continuous addition of nodes), and its robustness (no network failure during 7 years of operation). The possibility to share VME units as well as PC units enable us to strongly increase the available real-time CPU power. The development of advanced real-time plasma control algorithms becomes thus accessible. The real-time equilibrium reconstruction is a first example of such a generation of algorithms. (A.C.)

  17. SPECIAL ISSUE DEVOTED TO THE 80TH ANNIVERSARY OF ACADEMICIAN N G BASOV'S BIRTH: A capillary discharge plasma source of intense VUV radiation

    Science.gov (United States)

    Sobel'man, Igor I.; Shevelko, A. P.; Yakushev, O. F.; Knight, L. V.; Turley, R. S.

    2003-01-01

    The results of investigation of a capillary discharge plasma, used as a source of intense VUV radiation and soft X-rays, are presented. The plasma was generated during the discharge of low-inductance condensers in a gas-filled ceramic capillary. Intense line radiation was observed in a broad spectral range (30-400 Å) in various gases (CO2, Ne, Ar, Kr, Xe). The absolute radiation yield for the xenon discharge was ~5 mJ (2π sr)-1 pulse-1 within a spectral band of width 9 Å at 135 Å. Such a radiation source can be used for various practical applications, such as EUV projection lithography, microscopy of biological objects in a 'water window', reflectometry, etc.

  18. Non-thermal plasma discharge based NO{sub x} removal system for diesel engine exhaust

    Energy Technology Data Exchange (ETDEWEB)

    Federle, S.P.; Littrell, D.M. [Armament Directorate, Eglin AFB, FL (United States). Wright Lab.; Wander, J. [Environics Directorate, Tyndall AFB, FL (United States). Armstrong Lab.; Rogers, J.W.; Nejezchleb, A.J.; Rolader, G.E. [Science Application International Corp., Shalimar, FL (United States); Canfield, A. [ARA, Tyndall AFB, FL (United States)

    1997-12-31

    Emission regulations are becoming increasingly stringent on Aerospace Ground Equipment (AGE) at several Air Force bases. The problems are particularly acute for Air Force bases in California, such as March, Vandenberg, and McClellan. The most pressing regulatory problem is the emissions of nitrogen oxides from the A/M32A-86 (-86) diesel-powered generator. In response to this problem, the Air Force started the Green AGE program for advanced technology demonstrations. As part of the Green AGE program, the Armstrong Laboratory, Environics Directorate at Tyndall AFB and the Wright Laboratory, Armament Directorate at Eglin AFB were selected to jointly demonstrate that a Non-Thermal Plasma Discharge (NTPD) based system could remove the NO{sub x} from the -86 exhaust. A -86 generator was installed at Site A-15 of Eglin AFB, and a portion of the exhaust diverted to flow through a complete NTPD system. The system is comprised of a particle filter, reactor tube, and conventional wet scrubber. The particle filter removes particulates. The reactor tube oxidizes the nitric oxide into nitrogen dioxide and acid compounds, which can be removed by a conventional wet scrubber. Many experiments were performed to optimize the system. It was found that the injection of ethanol upstream of the reactor tube drastically reduced the energy required for nitric oxide oxidation. In addition, using Teflon PFA dielectrics was found to be superior to glass. In this paper, the applicable regulations are summarized; and estimates on the size, weight, and cost of a fieldable system are presented. In addition, the design, construction, and testing of each component from the demonstration program is described and results from the many optimization experiments are reported.

  19. Influence of ionic liquid and ionic salt on protein against the reactive species generated using dielectric barrier discharge plasma.