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Sample records for barrier discharge plasma

  1. Modelling of dielectric barrier discharge plasma actuators with thick electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Hoskinson, A R; Hershkowitz, N, E-mail: hershkowitz@engr.wisc.edu [Department of Engineering Physics, University of Wisconsin-Madison, Madison, WI 53706 (United States)

    2011-03-02

    We have developed a new two-dimensional fluid simulation to model the plasma dynamics in surface dielectric barrier discharges operating in air. Single-barrier (one electrode insulated) and double-barrier (both electrodes insulated) discharges have been observed to generate a force in the nearby air, making them potentially useful as aerodynamic actuators. Many previous simulations of such discharges have modelled the electrodes as thin strips. We instead consider plasma actuators including cylindrical electrodes of various sizes. In single-barrier actuators, the size of the exposed electrode qualitatively affects the discharge dynamics, particularly with a negative-going applied voltage. For both geometries, the simulations predict the formation of plasma structures similar to those imaged in previous experiments. Experimentally observed increases in forces for actuators with smaller high-voltage electrodes were only reproduced for the single-barrier geometry. Due to limitations of computational power, voltage rates of change for all simulations were higher than those used in experiments.

  2. Research on using dielectric barrier discharges for plasma generation

    International Nuclear Information System (INIS)

    In this paper a method that generation atmospheric plasma using dielectric barrier discharges (DBD) is given. Through the experiments, discharges current curves are obtained separately at 10 kHz and 500 kHz AC supply. The curves show that there are floating ions (plasma) between two dielectric plates. The floating ions can be blown out by airflow. The density of ions in plasma blown is measured

  3. On the mechanical efficiency of dielectric barrier discharge plasma actuators

    NARCIS (Netherlands)

    Giepman, R.H.M.; Kotsonis, M.

    2011-01-01

    The mechanical power production and electrical power consumption of the dielectric barrier discharge plasma actuator is investigated for different operating conditions. The ratio of these two values delivers the mechanical efficiency of the actuator as a flow acceleration device. The general trend i

  4. 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

  5. Bacterial Inactivation by Atmospheric Pressure Dielectric Barrier Discharge Plasma Jet

    Science.gov (United States)

    Deng, Sanxi; Cheng, Cheng; Ni, Guohua; Meng, Yuedong; Chen, Hua

    2008-08-01

    Bacillus subtilis and Escherichia coli seeded in two media (agar and filter papers) were exposed to after-glow plasma emitted from a atmospheric pressure dielectric barrier discharge (DBD) plasma jet generator in open air with a temperature of about 30-80 °C. In order to estimate the inactivation of microorganism using DBD plasma jet, various plasma conditions (such as treatment time and feed-gas composition of plasma jet) were changed. The results shown that the effective area of inactivation increased with the plasma treatment time as the bacteria seeded in Agar medium. The effective area of inactivation was much bigger than plasma jet treatment area after 5 min treatment. With the use of filter papers as the supporting media, the addition of reactive gases (oxygen, hydrogen peroxide vapor) into the plasma jet system, compared with only pure noble gas, led to a significant improvement in the bacterial Inactivation efficacy.

  6. 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.

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

    International Nuclear Information System (INIS)

    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

  8. 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.

  9. Dielectric barrier Discharge Plasma Actuator Characterization and Application

    OpenAIRE

    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 bounded of free shear layers were performed. Amplitude and location of the input with respect to the receptivity region as well as frequency of flow actuation were investigated. This work required the...

  10. Characteristics of dielectric barrier discharge plasmas in atmospheric humid air

    Science.gov (United States)

    Fukuda, Y.; Fukui, K.; Iwami, R.; Matsuoka, Y.; Kikuchi, Y.; Fukumoto, N.; Nagata, M.

    2012-10-01

    Atmospheric pressure plasmas have a great advantage for industrial applications such as surface modifications, sterilization and film preparation. In particular, reactive plasmas including OH radicals can be generated in humid air. On the other hand, it is known that dielectric barrier discharge (DBD) plasmas in air are strongly affected by humidity. In this study, a twisted pair sample is used as a DBD electrode. The twisted pair consists of two enameled wires, and it is installed in a climate chamber to control ambient temperature and humidity. Repetitive impulse voltage pulses were applied to the twisted pair to produce DBD plasmas. Light emission, electromagnetic wave and current pulses were used to detect discharge activities. The discharge inception voltage (DIV) is basically determined by Paschen curve in air, however, the DIV was decreased by increasing the humidity. In addition, it was found that there were largely scattered data of DIV at the low humidity condition. After the pre-discharges, the DIV reached to the steady state value. On the other hand, there was no scattering of the observed DIV at the high humidity condition. Measurements of surface potential of the sample after the discharge show these behaviors could be explained by surface charge accumulation on the enameled wire. It is noted that there was no fluctuation in the DIV data in the case of unipolar voltage pulse.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. Effect of Dielectric and Liquid on Plasma Sterilization Using Dielectric Barrier Discharge Plasma

    OpenAIRE

    Mastanaiah, Navya; Johnson, Judith A.; Roy, Subrata

    2013-01-01

    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 ...

  17. Theoretical modeling of pulse discharge cycle in dielectric barrier discharge plasma actuator

    Science.gov (United States)

    Sato, Shintaro; Ohnishi, Naofumi

    2016-07-01

    Simple models based on two-dimensional simulations are proposed to estimate intervals of periodically observed current pulses with a positive-going voltage in a dielectric barrier discharge plasma actuator. There are two distinct peaks in one streamer discharge; one is related to the formation of an ion cloud and the other is related to a filamentary discharge that is identified as a streamer. Simulation results show that the intervals of the current pulses depend on the slope of the applied voltage. For the ion-cloud formation phase, we model the time evolution of electron number density at the exposed electrode with ionization frequency. For the ion-cloud expansion phase, a positive ion cylinder model is proposed to estimate the electric field generated by surface charge on the dielectric. These models well reproduce the discharge intervals obtained in the numerical simulations.

  18. The cleaning process of metal surfaces in barrier discharge plasmas

    International Nuclear Information System (INIS)

    The cleaning process of metal surfaces was studied, which were used as one of the electrodes of planar barrier discharges. The barrier electrodes were made from ferroelectric ceramics. The discharges operated in flowing oxygen and air at atmospheric pressure. The metal probes were covered by defined layers of special oils. The dependence of the cleaning process on the gas flow was observed with optical emission spectroscopy. A clean surface has been reached only at low gas flows (1-5 l/h). At higher gas flows the lubricant could not be removed completely because of polymerization of the oil. With GC/MS capillary chromatography CO2 was detected as the final reaction product. The comparison of the cleaning effect in air and pure oxygen showed a higher efficiency of the air discharge. The surface situation was controlled by spectroscopic ellipsometry and XPS. (author)

  19. 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)

  20. 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.

  1. 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.

  2. Surface modification of polyethylene by diffuse barrier discharge plasma

    Czech Academy of Sciences Publication Activity Database

    Novák, I.; Števiar, M.; Popelka, A.; Chodák, I.; Mosnáček, J.; Špírková, Milena; Janigová, I.; Kleinová, A.; Sedliačik, J.; Šlouf, Miroslav

    2013-01-01

    Roč. 53, č. 3 (2013), s. 516-523. ISSN 0032-3888 R&D Projects: GA AV ČR(CZ) IAAX08240901 Institutional research plan: CEZ:AV0Z40500505 Keywords : low-density polyethylene * plasma discharge * surface modification Subject RIV: JI - Composite Materials Impact factor: 1.441, year: 2013

  3. Plasma Treatment of Industrial Landfill Leachate by Atmospheric Pressure Dielectric Barrier Discharges%Plasma Treatment of Industrial Landfill Leachate by Atmospheric Pressure Dielectric Barrier Discharges

    Institute of Scientific and Technical Information of China (English)

    赵迪; 王达成; 严贵; 马宏; 熊小京; 罗津晶; 张先徽; 刘东平; 杨思泽

    2011-01-01

    An dielectric barrier discharge (DBD) system in atmospheric pressure utilized for the treatment of industrial landfill leachate is reported. The discharge parameters, such as the operating frequency, gas flow rate, and treating duration, were found to affect significantly the removal of ammonia nitrogen (AN) in industrial landfill leachate. An increase in treating duration leads to an obvious increase in the removal efficiency of AN (up to 83%) and the leachate color changed from deep grey-black to transparent. Thus the dielectric barrier discharges in atmospheric pressure could degrade the landfill leachate effectively. Typical waveforms of both applied voltage and discharge current were also presented for analyzing the discharge processes under different discharge parameters. Optical emission spectra measurements indicate that oxidation species generated in oxygen DBD plasma play a crucial role in removing AN, oxidizing organic and inorganic substances and decolorizing the landfill leachate.

  4. 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...

  5. Plasma Diagnostics and Modelling of Nanosecond Pulsed Surface Dielectric Barrier Discharge Actuators

    OpenAIRE

    Goekce, Sami

    2014-01-01

    During the past years, an increasing number of studies have been conducted on the use of electrical discharges for the stabilization of airflows (plasma flow control). Electrical gas discharges transfer energy and momentum to the gas through collisions of free electrons with atoms and molecules. Chemically active species such as ions, radicals and excited species are produced due to these collisions. The use of plasma actuators, notably surface dielectric barrier discharges (SDBD), for flow c...

  6. 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.

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

    OpenAIRE

    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

    2015-01-01

    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....

  8. Plasma Surface Treatment of Polypropylene Reinforcing Fibres by Dielectric Barrier Discharge

    OpenAIRE

    Morávek Tomáš; Ráheľ Jozef; Szalay Zsolt

    2013-01-01

    This article deals with plasma treatment of polypropylene fibres used as concrete admixtures for improving its mechanical properties. Plasma treatment was conducted in low-temperature plasma at atmospheric pressure. Dielectric barrier discharges in both coplanar and volume configuration of electrodes were used for this purpose. The degree of hydrophilicity caused by plasma treatment was determined by measuring the rate of penetration of liquids into the porous media, so called Washburn method...

  9. Diamond-like films deposited in the plasma of barrier and surface discharges at atmospheric pressure

    International Nuclear Information System (INIS)

    The structure and properties were investigated of carbon coatings deposited in the plasma of barrier and surface discharges at atmospheric pressure. To examine the structure of the coatings, methods of transmission electron microscopy and electron diffraction analysis were used. The coatings produced in a barrier discharge in methane and in acetylene-hydrogen mixtures are similar in chemical and phase composition to amorphous diamond-like carbon films produced at low pressures by conventional deposition techniques. However, the coatings have a significant number of defects, evidently caused by the inherent microstructure of the barrier discharge. From this point of view, the use of a surface discharge is much more promising. The coatings produced in a surface discharge have almost no microdefects and both the spatial distribution of the energy delivered to the discharge and the transport of film-forming particles towards the substrate are more efficient. (J.U.)

  10. PEO-like Plasma Polymers Prepared by Atmospheric Pressure Surface Dielectric Barrier Discharge

    Czech Academy of Sciences Publication Activity Database

    Gordeev, I.; Choukourov, A.; Šimek, Milan; Prukner, Václav; Biederman, H.

    2012-01-01

    Roč. 9, č. 8 (2012), s. 782-791. ISSN 1612-8850 R&D Projects: GA ČR(CZ) GD104/09/H080 Institutional research plan: CEZ:AV0Z20430508 Keywords : fibrinogen * non-fouling properties * PEO * plasma polymerization * surface dielectric barrier discharge Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.730, year: 2012

  11. Measurements and Simulations of Surface Dielectric Barrier Discharges Used as Plasma Actuators

    Science.gov (United States)

    Hoskinson, Alan R.

    2012-01-01

    This report is a Ph.D. dissertation performed under NRA cooperative agreement and submitted as part of the final report. Asymmetric surface dielectric barrier discharges (DBDs) have shown promise for use as aerodynamic actuators for active flow control. In this project we studied DBD actuators experimentally and numerically. Our DBDs used a symmetric triangular high voltage waveform to generate plasma in atmospheric pressure air. Time-averaged measurements indicated that the induced force of a single barrier actuator design (one electrode insulated from the plasma) can be increased exponentially above the results of previous studies by decreasing both the length and thickness of the electrode exposed to the plasma. This increased force may allow these devices to control flow separation in a wider range of flow environments. Experiments using an intensified digital camera to examine the plasma on time scales of a few nanoseconds showed that, in addition to the previously-observed filamentary and jet-like plasma structures, discharges with very thin exposed electrodes exhibited a weak but constant plasma immediately adjacent to those electrodes. In double-barrier actuators (both electrodes insulated), decreasing the diameter of the narrower electrode lead to increasing forces, and recorded images showed the simultaneous existence of both filamentary and jet-like plasma structures. The development and application of a time-dependent, two-dimensional computational fluid plasma model has aided in understanding the detailed physics of surface DBDs at all-time scales. For simulated single-barrier discharges, the model qualitatively reproduced the filamentary and jet-like micro-discharge structures. The model was somewhat successful in reproducing the observed characteristics of double-barrier actuators. For both actuator geometries, the model indicated that the majority of the forces induced on the neutral gas occur in between micro-discharges as the plasmas decay.

  12. Enhancement of Oil Spreadability of Biscuit Surface by Nonthermal Barrier Discharge Plasma

    OpenAIRE

    Misra, N.; Sullivan, Carl; Pankaj, Shashi; Alvarez-Jubete, Laura; Cama, Raquel; Jacoby, Franklyn; Cullen, Patrick

    2014-01-01

    The application of non-thermal dielectric barrier discharge (DBD) plasma for altering the hydrophilicity or hydrophobicity of polymer surfaces is well known. In this work, we demonstrate the potential of DBD plasma in enhancing the surface hydrophobicity of freshly baked biscuits, evident from the increased spread area of vegetable oil. The electrical and optical characteristics of the DBD plasma source have also been described. The spread area of individual oil drops has been measured using ...

  13. On the Nature and Behavior of Filaments in the Dielectric Barrier Discharge of Plasma Actuators

    OpenAIRE

    Bürkle, Sebastian

    2013-01-01

    Plasma actuators based on dielectric barrier discharge (DBD) promise a bright future in aerodynamical applications. By creating a body force in the surrounding gas through plasma – gas interaction, plasma actuators operated in quiescent air induce a small flow above their surface with a velocity of typically 5-8 m/s, the so called ionic wind. The ionic wind can influence the boundary-layer of an externally applied flow surrounding the actuator. Unfortunately, the origin of the body force that...

  14. Plasma Treatment of Industrial Landfill Leachate by Atmospheric Pressure Dielectric Barrier Discharges

    International Nuclear Information System (INIS)

    An dielectric barrier discharge (DBD) system in atmospheric pressure utilized for the treatment of industrial landfill leachate is reported. The discharge parameters, such as the operating frequency, gas flow rate, and treating duration, were found to affect significantly the removal of ammonia nitrogen (AN) in industrial landfill leachate. An increase in treating duration leads to an obvious increase in the removal efficiency of AN (up to 83%) and the leachate color changed from deep grey-black to transparent. Thus the dielectric barrier discharges in atmospheric pressure could degrade the landfill leachate effectively. Typical waveforms of both applied voltage and discharge current were also presented for analyzing the discharge processes under different discharge parameters. Optical emission spectra measurements indicate that oxidation species generated in oxygen DBD plasma play a crucial role in removing AN, oxidizing organic and inorganic substances and decolorizing the landfill leachate.

  15. 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.

  16. Theoretical and experimental investigation of the plasma source with argon rf barrier discharge at atmospheric pressure

    International Nuclear Information System (INIS)

    Glow characteristics of capacitive radio frequency discharge with isolated electrodes in atmospheric pressure argon in low-current and high-current modes are determined experimentally and calculated by the hybrid hydrodynamic model. Comparative analysis of obtained experimental data and simulated spatio-temporal distributions of concentrations of discharge plasma electrons and heavy species, mean energy of electrons in the RF barrier discharge enabled interpretation of the discharge structure peculiarities in low-current α,α-gamma transition and high-current modes.

  17. Plasma propagation of a 13.56 MHz asymmetric surface barrier discharge in atmospheric pressure air

    Energy Technology Data Exchange (ETDEWEB)

    Dedrick, J; Boswell, R W; Charles, C [Space Plasma, Power and Propulsion Group, Research School of Physics and Engineering, The Australian National University, ACT 0200 (Australia); Audier, P; Rabat, H; Hong, D, E-mail: james.dedrick@anu.edu.au [GREMI - UMR6606 CNRS/Universite d' Orleans, Polytech' Orleans, 14, rue d' Issoudun - BP6744, 45067 ORLEANS Cedex 2 (France)

    2011-05-25

    The propagation of an rf asymmetric surface barrier discharge in atmospheric pressure air has been investigated. Measurements of the pulse-modulated 13.56 MHz voltage and current together with ICCD images of the plasma were recorded to study the visible plasma structure with respect to the rf pulses, time within the pulses and the rf waveforms. When exposing images over full rf pulses, which comprise over 150 oscillations of the applied voltage, clearly defined filamentary structures are observed indicating a strong memory effect. The discharge intensity decreases exponentially with distance from the electrode edge, and the average propagation length increases linearly with the applied voltage. Similar to some lower frequency asymmetric surface dielectric barrier discharges, two distinct breakdown events occur during one period of the voltage waveform. The number of filaments is found to be the same for both breakdown events, and collective effects are observed in both discharges.

  18. Methane activation under dielectric barrier discharge plasma interacting with mesoporous material

    OpenAIRE

    Kim, J; Park, D; Lee, C.(Institute of Physics, Academia Sinica, Taipei, Taiwan); Lee, D H; Kim, T.

    2015-01-01

    International audience Direct methane activation on a mesoporous material under dielectric barrier discharge (DBD) plasma was investigated in the present study. The specific surface area of the mesoporous material (SBA-15) was controlled by varying the hydrothermal reaction temperature to investigate the effect of the specific surface area on the methane activation. As a result, methane conversion increased as the specific surface area increased and the discharge frequency decreased. Energ...

  19. Inactivation of Spoilage Bacteria in Package by Dielectric Barrier Discharge Atmospheric Cold Plasma - Treatment Time Effects

    Science.gov (United States)

    The objective was to investigate the effect of treatment time of dielectric barrier discharge atmospheric cold plasma (DBD-ACP) on inactivation of spoilage bacteria, Pseudomonas fluorescens and Macrococcus caseolyticus. P. fluorescens and M. caseolyticus were isolated from spoiled chicken carcasses ...

  20. 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.

  1. Measurement of OH Radicals in Dielectric Barrier Discharge Plasmas by Cavity Ring-Down Spectroscopy

    International Nuclear Information System (INIS)

    Near-infrared continuous wave cavity ring-down spectroscopy was applied to measure the OH radicals in dielectric barrier discharge plasmas, which play an important role in combustion systems, atmospheric chemistry and the removal of air pollutants by non-thermal plasmas. The P-branches of OH X2Πi ν = 2 <- ν = 0) bands were used for number density measurements. The OH number density and plasma temperature were determined for different applied voltages, gas pressures and concentrations of both oxygen and water. The temporal evolution of the OH number density was obtained by using the 'time window' method, which was used to extract individual ring-down times at different times in a half period of the sine wave applied voltage in dielectric barrier discharge plasmas.

  2. Applications of Dielectric Barrier Discharges and Plasma Synthetic Jet Actuators at ONERA

    OpenAIRE

    Chedevergne, F.; Casalis, G; Léon, O.; Forte, M.; Laurendeau, F.; Szulga, N.; Vermeersch, O.; Piot, E.

    2015-01-01

    This paper focuses on two plasma actuators, developed at ONERA: the DBD actuator (Dielectric Barrier Discharge) and the PSJ actuator (Plasma Synthetic Jet). At the DMAE (Modeling for Aerodynamics and Energetics Department), DBD actuation is investigated for laminar/transition purposes. The results presented deal with 2D configurations including both experimental and modeling works. As regards the activities on the PSJ actuator, most of the work is dedicated to the detailed characterization of...

  3. 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....

  4. 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.

  5. 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.

  6. Thrust Measurement of Dielectric Barrier Discharge (DBD) Plasma Actuators

    Science.gov (United States)

    Ashpis, David E.; Laun, Matthew C.

    2013-11-01

    DBD plasma actuators generate a wall-jet that can be used for active flow control. We used an analytical balance to measure the thrust generated by the actuator, it is a common metric of its performance without external flow. We found that the measured force is afflicted by several problems; it drifts in time, not always repeatable, is unstable, and depends on the manner the voltage is applied. We report results of investigations of these issues. Tests were conducted on an actuator constructed of 1/4 inch thick high-density polyethylene (HDPE) dielectric with 100 mm long offset electrodes, with applied voltages up to 48 kV p-p and frequencies from 32 Hz to 2.5 kHz, and pure Sine and Trapezoidal waveforms. The relative humidity was in the range of 51-55%, corresponding to moisture range of 10,500 to13,000 ppm mass. Force readings were up to 500 mg, (approximately 50 mN/m). We found that the measured force is the net of the positive thrust generated by the wall-jet and an ``anti-thrust'' acting in the opposite direction. We propose a correction procedure that yields the plasma-generated thrust. The correction is based on voltage-dependent anti-thrust measured in the low frequency range of 20-40 Hz. We found that adjacent objects in a test setup affect the measured thrust, and verified it by comparing experiments with and without a metal enclosure, grounded and ungrounded. Uncorrected thrust varied by up to approximately +/-100%, and the corrected thrust variations were up to approximately 30%. Supported by NASA's FAP/Aerospace Sciences Project.

  7. 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. PMID:25641832

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

    Science.gov (United States)

    Kim, Ki Cheon; Piao, Mei Jing; Madduma Hewage, Susara Ruwan Kumara; 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'-dichlorodihydrofluorescein 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

  9. Development of Low-Temperature Atmospheric Coaxial Dielectric Barrier Discharge (DBD) Plasma Source

    International Nuclear Information System (INIS)

    Full text: Low-temperature atmospheric plasma has played an increasingly important role in various industrial, medical, and research applications. Nevertheless, this type of plasma usually has low density which imposes a limit on its effectiveness and the type of work that it can be applied to. In this research, a low-temperature atmospheric plasma source has been designed and developed using the dielectric barrier discharge (DBD) plasma production technique. The source is designed to have coaxial geometry for future utilization in medical sterilization. The effects of the amplitude and frequency of the driving potential on the temperature and spectrum of plasma have been studied. It is found that with the amplitudes and frequencies of the driving potentials that can be supplied by the available power supply, similar plasma spectrum have been obtained and the electron temperatures are measured between 4-5 eV

  10. Emission properties of an atmospheric pressure argon plasma jet excited by barrier discharge

    International Nuclear Information System (INIS)

    An atmospheric-pressure argon plasma jet is initiated by the barrier discharge in a capillary, through which argon was flown. The spectral composition of radiation emitted by the jet in the atmosphere and its variation in the space are analyzed in detail. The jet radiation spectrum is shown to be predominantly formed by spectral transitions of argon and oxygen atoms, by electron-vibrational transitions of the first positive system of nitrogen molecules N2, and by transitions of hydroxyl radical OH

  11. UNJUK KERJA REAKTOR PLASMA DIELECTRIC BARRIER DISCHARGE UNTUK PRODUKSI BIODIESEL DARI MINYAK KELAPA SAWIT

    OpenAIRE

    Ardian Dwi Yudhistira; Istadi Istadi

    2013-01-01

    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 ...

  12. Removal of priority pollutants from water by means of dielectric barrier discharge atmospheric plasma

    OpenAIRE

    Hijosa-Valsero, M.; Molina, R.; Schikora, H.; Müller, M.; Bayona, J M

    2013-01-01

    Two different nonthermal plasma reactors at atmospheric pressure were assessed for the removal of organic micropollutants (atrazine, chlorfenvinfos, 2,4-dibromophenol, and lindane) from aqueous solutions (1-5 mg L-1) at laboratory scale. Both devices were dielectric barrier discharge (DBD) reactors; one was a conventional batch reactor (R1) and the other a coaxial thin-falling-water-film reactor (R2). A first-order degradation kinetics was proposed for both experiments. The kinetic constants ...

  13. Plasma surface treatments by using a dielectric barrier discharge for the deposition of diamond films

    Science.gov (United States)

    Kang, I. J.; Ko, M. G.; Yang, J. K.; Lee, H. J.

    2013-07-01

    For plasma surface treatments at atmospheric pressure, a 2 kW dielectric barrier discharge (DBD) source was developed. It was investigated via an optical emission spectroscopy (OES), an IR camera and volt-ampere meters with a computer. It was confirmed that the developed source stably generated plasmas. After the diamonds had been seeded, the plasma surface treatments were performed as pretreatment to improve the deposition of the diamond films by using the developed DBD source with argon gas. The substrate surfaces were analyzed using a contact angle analysis (CAA), an atomic force microscopy (AFM) and a 3D Nano Profiling System. The results of the plasma surface treatments showed an improvement in the surface free energies of the substrates. The plasma surface treatments for 5 minutes also resulted in a more uniform distribution of the seeding diamonds on the substrates, which improved the depositions of the diamond films.

  14. Atomic oxygen generation by in-situ plasma and post-plasma in dielectric barrier discharges for surface treatment

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Woo Seok; Kim, Hyun-Su [Department of Nuclear Engineering, Seoul National University, Seoul (Korea, Republic of); Hong, Sang Hee, E-mail: hongsh@snu.ac.k [Department of Nuclear Engineering, Seoul National University, Seoul (Korea, Republic of)

    2010-09-01

    Atomic oxygen (AO) generation is experimentally and numerically investigated for in-situ plasma and post-plasma produced by dielectric barrier discharges (DBDs) for surface treatment. The AO generation in in-situ plasma inside a DBD reactor is closely related to the plasma characteristics depending on the applied voltage and O{sub 2} additive concentration, while the AO density distribution along the post-plasma ejected outside the reactor exit is influenced by the AO generation in the in-situ plasma, gas flow rate, and effluent distance. Contact angle measurements show that the metal surface characteristics, which are treated by in-situ plasma and post-plasma, respectively, are distinctive from each other depending on the AO densities.

  15. 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

  16. Differences between dielectric barrier discharge plasma actuators with cylindrical and rectangular exposed electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Hoskinson, A R; Hershkowitz, N, E-mail: hershkowitz@engr.wisc.ed [Department of Engineering Physics, University of Wisconsin-Madison, Madison, WI 53706 (United States)

    2010-02-17

    Surface dielectric barrier discharges (DBDs) used as plasma actuators can induce significant time-averaged forces in nearby neutral gases. For single-barrier actuators (one electrode insulated) these forces are dependent on the geometry of the exposed electrode. We demonstrate that using thin cylindrical exposed electrodes can increase the induced force by several hundred percent compared with an actuator with a rectangular exposed electrode of the same thickness. This difference is due almost exclusively to the extent of the exposed electrode in the same direction as the gap between the two electrodes, which tends to be much longer for actuators constructed with rectangular exposed electrodes. The exact shape of the electrode cross-section plays no role. In addition, using an intensified digital camera we observed a new filament-free plasma that occurred only in discharges with exposed electrodes smaller than approximately 0.15 mm in diameter. These discharges spent an increasing fraction of the applied voltage period in this mode as we reduced the exposed electrode diameter. The mode shared several characteristics with a positive corona, and was partially responsible for a decrease in the electrical power used by these discharges.

  17. High-speed sterilization technique using dielectric barrier discharge plasmas in atmospheric humid air

    Science.gov (United States)

    Miyamae, M.; Kikuchi, Y.; Fukumoto, N.; Nagata, M.

    2010-11-01

    The inactivation of Bacillus atrophaeus spores by a dielectric barrier discharge (DBD) plasma produced by an ac voltage application of 1 kHz in atmospheric humid air was investigated in order to develop low-temperature, low-cost and high-speed plasma sterilization technique. The biological indicators covered with a Tyvek sheet were set just outside the DBD plasma region, where the air temperature and humidity as a discharge gas were precisely controlled by an environmental test chamber. The results show that the inactivation of Bacillus atrophaeus spores was found to be dependent strongly on the humidity, and was completed within 15 min at a relative humidity of 90 % and a temperature of 30 C. The treatment time for sterilization is shorter than those of conventional sterilization methods using ethylene oxide gas and dry heat treatment. It is considered that reactive species such as hydroxyl radicals that are effective for the inactivation of Bacillus atrophaeus spores could be produced by the DBD plasma in the humid air. Repetitive micro-pulsed discharge plasmas in the humid air will be applied for the sterilization experiment to enhance the sterilization efficiency.

  18. Detection of hydroxyl radicals during regeneration of granular activated carbon in dielectric barrier discharge plasma system

    International Nuclear Information System (INIS)

    To understand the reactions taking place in the dielectric barrier discharge (DBD) plasma system of activated carbon regeneration, the determination of active species is necessary. A method based on High Performance Liquid Chromatography with radical trapping by salicylic acid, has been developed to measure hydroxyl radical (.OH) in the DBD plasma reactor. The effects of applied voltage, treatment time, and gas flow rate and atmosphere were investigated. Experimental results indicated that increasing voltage, treatment time and air flow rate could enhance the formation of .OH. Oxygen atmosphere and a suitable GAC water content were contributed to .OH generation. The results give an insight into plasma chemical processes, and can be helpful to optimize the design and application for the plasma system.

  19. A novel cold plasma jet generated by capillary atmospheric dielectric barrier discharge

    International Nuclear Information System (INIS)

    An easy-operated and effective scheme is presented to generate a novel kind of atmospheric cold plasma millimeter jet. The jet operates with many kinds of working gas at atmosphere pressure, such as Ar, He and N2, in a capillary quartz dielectric barrier discharge (DBD) system powered by a pulsed power source with a frequency of 33 kHz and variable voltage of 1-12 kV. Via a CCD imager, the initial discharge filaments in the DBD gap are found to be transformed into diffusion discharge or glow-like discharge by the flowing gas through the DBD gap, and a plasma jet formed in the outlet of the capillary is viewed simultaneously. The critical velocity of the gas flow for the plasma jet formation is determined to be 3-8 m/s for different working gases by a well-designed enthalpy probe. The jet range for a special gas can be changed by the increase of the gas flow velocity while the jet range for different gases varies a lot and the helium jet takes the longest range of about 44 mm when the helium flows at a velocity of about 20 m/s. Beyond the velocity limit of 20 m/s for laminar helium flow, the jet of helium plasma becomes torrent and unstable and its range turns shorter. Based on the OES analysis of He plasma jets, it is determined that the excitation temperature of He jets lay in the range 2000 K-3000 K, which is much lower than the excitation temperature of a normal arc plasma torch and hints that the jet is cold especially when compared to the arc plasma torch. (authors)

  20. 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.

  1. 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.

  2. 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.

  3. Estudi de la vida útil d'aliments envasats tractats amb Dielectric Barrier Discharge Plasma

    OpenAIRE

    Messari Jouid, Fatima

    2015-01-01

    It was just a few years ago when the first studies about the utility of DBD (Dielectric Barrier Discharge) treatment on the microbial reduction of food. Is for this reason that, at the moment, there are few published studies. The most useful literature found comes the physics and chemistry fields. The aim of this study is the evaluation of the effect of DBD plasma treatment in orange juice, whole milk, dried tomato soup and cocoa powder, thinking about the possibility of using this technology...

  4. 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. PMID:26421625

  5. Pattern formation and dynamics of plasma filaments in dielectric barrier discharges

    International Nuclear Information System (INIS)

    Dielectric barrier discharges (DBDs) operating in a transient glow discharge regime offer a large variety of self-organized filamentary static or dynamical structures and constitute an excellent physical system for the study of nonlinear dynamics and pattern formation. The plasma filaments of DBDs can exhibit particle-like behavior, with motion, generation, annihilation, and scattering as well as collective effects leading to self-organized structures (hexagons, stripes, concentric rings, spirals, etc) that are typical of reaction–diffusion systems. The purpose of this paper is to analyze the detailed physics of pattern formation in DBDs on the basis of numerical fluid simulations and experiments in order to provide a deeper understanding of the nonlinear mechanisms responsible for the self-organization and dynamics of filaments. (paper)

  6. 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.

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

    International Nuclear Information System (INIS)

    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

  8. 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.

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

    International Nuclear Information System (INIS)

    Highlights: • We used an economical and effective method for surface modification. • Chitosan/PEO nanofibrous membranes were modified by air-DBD plasma. • The most NH3+ 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 NH3+ 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 NH3+ 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

  10. Electron energy distribution functions for modelling the plasma kinetics in dielectric barrier discharges

    International Nuclear Information System (INIS)

    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. Decomposition of trifluoromethane in a dielectric barrier discharge non-thermal plasma reactor

    Institute of Scientific and Technical Information of China (English)

    M. Sanjeeva Gandhi; Y. S. Mok

    2012-01-01

    The decomposition of trifluoromethane (CFF3) was carried out using non-thermal plasma generated in a dielectric barrier discharge (DBD) reactor.The effects of reactor temperature,electric power,initial concentration and oxygen content were examined.The DBD reactor was able to completely destroy CHF3 with alumina beads as a packing material.The decomposition efficiency increased with increasing electric power and reactor temperature.The destruction of CHF3 gradually increased with the addition of O2 up to 2%,but further increase in the oxygen content led to a decrease in the decomposition efficiency.The degradation pathways were explained with the identified by-products.The main by-products from CHF3 were found to be COF2,CF4,CO2 and CO although the COF2 and CF4 disappeared when the plasma were combined with alumina catalyst.

  12. Formaldehyde removal from gas streams by means of NaNO2 dielectric barrier discharge plasma

    International Nuclear Information System (INIS)

    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, CO2 and H2O.

  13. Some observations on plasma-assisted combustion enhancement using dielectric barrier discharges

    Energy Technology Data Exchange (ETDEWEB)

    Tang Jie; Zhao Wei; Duan Yixiang, E-mail: yduan@scu.edu.cn, E-mail: yxd@opt.ac.cn [State Key Laboratory of Transient Optics and Photonics, Xi' an Institute of Optics and Precision Mechanics of CAS, Xi' an (China)

    2011-08-15

    We explore an effective way to promote propane combustion by applying a plasma discharge for efficiency enhancement. A coaxial-cylinder, dielectric barrier discharge is used to activate propane and air before they are mixed with each other and ignited for combustion. The characteristics of the combustion flame are well studied and evaluated by varying various operational parameters. It is found that the combustion process can be enhanced by applying a plasma on either the propane or air stream, and the combustion stability is found to be somewhat sensitive to the lean burning conditions and confined to a relatively narrow operating window. The temperature and spectrum of the flame in the main combustion zone are investigated with a 4 W plasma in the on or off state. The main components are identified, and the possible physical and chemical reaction mechanisms are discussed. A comparative analysis of these spectra and temperatures obtained in the main flame suggests that the energy generated from the 4 W plasma is partially used to heat the reaction gases in the flame, and another part of the energy is used to increase the luminosity, especially for activation of air. We also observe that combustion of high flow rate propane and/or air requires more discharge energy density under certain conditions. A comparison of combustion enhancement through different activation methods in flame blowout tests shows that reactive species derived from activation of air play a more critical role in the blowout limit of propane combustion flame than those generated by activation of propane at low equivalence ratio and propane flow.

  14. Surface treatment of para-aramid fiber by argon dielectric barrier discharge plasma at atmospheric pressure

    International Nuclear Information System (INIS)

    Highlights: ► We use DBD technique to modify the surface of Kelvar29 fibers. ► The changed parameters include treated power, time and argon flux. ► There exists an optimum experimental condition of plasma treatment. ► Adhesion and wettability properties of fibers are improved through plasma treatment. - Abstract: This paper is focused on influence of argon dielectric barrier discharge (DBD) plasma on the adhesive performance and wettability of para-aramid fibers and three parameters including treated power, exposure time and argon flux were detected. The interfacial shear strength (IFSS) was greatly increased by 28% with 300 W, 60 s, 2 L min−1 argon flux plasma treatment. The content of oxygen atom and oxygen-containing polar functional groups were enhanced after the argon plasma treated, so as the surface roughness, which contributed to the improvement of surface wettability and the decrease of contact angle with water. However, long-time exposure, exorbitant power or overlarge argon flux could partly destroy the prior effects of the treatment and damage the mechanical properties of fibers to some degree.

  15. Dissipated power and induced velocity fields data of a micro single dielectric barrier discharge plasma actuator for active flow control☆

    Science.gov (United States)

    Pescini, E.; Martínez, D.S.; De Giorgi, M.G.; Francioso, L.; Ficarella, A.

    2015-01-01

    In recent years, single dielectric barrier discharge (SDBD) plasma actuators have gained great interest among all the active flow control devices typically employed in aerospace and turbomachinery applications [1,2]. Compared with the macro SDBDs, the micro single dielectric barrier discharge (MSDBD) actuators showed a higher efficiency in conversion of input electrical power to delivered mechanical power [3,4]. This article provides data regarding the performances of a MSDBD plasma actuator [5,6]. The power dissipation values [5] and the experimental and numerical induced velocity fields [6] are provided. The present data support and enrich the research article entitled “Optimization of micro single dielectric barrier discharge plasma actuator models based on experimental velocity and body force fields” by Pescini et al. [6]. PMID:26425667

  16. Plasma Filaments in Dielectric Barrier Discharges Penetrating into High Aspect Ratio Cracks for Sterilization

    Science.gov (United States)

    Babaeva, Natalia Yu.; Kushner, Mark J.

    2012-10-01

    The ability of surface-hugging-plasmas, as produced in dielectric barrier discharges (DBDs), to penetrate into crevices, turn corners and navigate geometrical obstructions, is important in plasma-wound healing and sterilization. In this talk, we discuss results from a computational investigation of the plasma filaments produced in an air DBD and impinging on and penetrating into deep, high aspect ratio cracks in the bottom dielectric. The model used in this work, nonPDPSIM, is a plasma hydrodynamics model in which continuity, momentum and energy equations are solved for charged and neutral species with solution of Poisson's equation for the electric potential, concurrent with radiation transport. A Monte Carlo simulation is used to obtain ion energy distributions (IEDs) to surfaces. Cracks are 1 mm deep and 3 μm to 250 μm wide (aspect ratios of 333 to 4). We found that when impinging onto the cracked dielectric, the plasma filament conformally spreads over the surface. The conductive plasma transfers the applied potential to the opening of the crack. The width of the crack, w, then determines the penetration of the plasma. If w is large compared to the filament, the penetration is surface hugging. If w is commensurate with the filament, the plasma fills the crack. If the Debye length is about w or larger, there is not significant penetration. For the conditions investigated, penetration occurred for w > 5-6 μm. IEDs onto the surfaces of the trenches produce transient pulses of ions with energies >150 eV.

  17. Dielectric barrier discharges in analytical chemistry.

    Science.gov (United States)

    Meyer, C; Müller, S; Gurevich, E L; Franzke, J

    2011-06-21

    The present review reflects the importance of dielectric barrier discharges in analytical chemistry. Special about this discharge is-and in contrast to usual discharges with direct current-that the plasma is separated from one or two electrodes by a dielectric barrier. This gives rise to two main features of the dielectric barrier discharges; it can serve as dissociation and excitation device and as ionization mechanism, respectively. The article portrays the various application fields for dielectric barrier discharges in analytical chemistry, for example the use for elemental detection with optical spectrometry or as ionization source for mass spectrometry. Besides the introduction of different kinds of dielectric barrier discharges used for analytical chemistry from the literature, a clear and concise classification of dielectric barrier discharges into capacitively coupled discharges is provided followed by an overview about the characteristics of a dielectric barrier discharge concerning discharge properties and the ignition mechanism. PMID:21562672

  18. 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.

  19. 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.

  20. Effects of electrode geometry on the performance of dielectric barrier/packed-bed discharge plasmas in benzene degradation

    International Nuclear Information System (INIS)

    Highlights: • Benzene was successfully degraded by dielectric barrier/packed-bed discharge plasmas. • Different electrode geometry has distinct effect on plasmas oxidation performance. • Benzene degradation and energy performance were enhanced when using the coil electrode. • The reaction products were well determined by online FTIR analysis. -- Abstract: In this study, the effects of electrode geometry on benzene degradation in a dielectric barrier/packed-bed discharge plasma reactor with different electrodes were systematically investigated. Three electrodes were employed in the experiments, these were coil, bolt, and rod geometries. The reactor using the coil electrode showed better performance in reducing the dielectric loss in the barrier compared to that using the bolt or rod electrodes. In the case of the coil electrode, both the benzene degradation efficiency and energy yield were higher than those for the other electrodes, which can be attributed to the increased role of surface mediated reactions. Irrespective of the electrode geometry, the packed-bed discharge plasma was superior to the dielectric barrier discharge plasma in benzene degradation at any specific applied voltage. The main gaseous products of benzene degradation were CO, CO2, H2O, and formic acid. Discharge products such as O3, N2O, N2O5, and HNO3 were also detected in the outlet gas. Moreover, the presence of benzene inhibited the formation of ozone because of the competing reaction of oxygen atoms with benzene. This study is expected to offer an optimized approach combining dielectric barrier discharge and packed-bed discharge to improve the degradation of gaseous pollutants

  1. Treatment of Candida albicans biofilms with low-temperature plasma induced by dielectric barrier discharge and atmospheric pressure plasma jet

    International Nuclear Information System (INIS)

    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 log10 reduction factor of 1.5, the log10 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.

  2. 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.

  3. Dynamic of the plasma current amplitude in a barrier discharge: influence of photocatalytic material

    International Nuclear Information System (INIS)

    For a better understanding of the plasma/photocatalytic material interaction under plasma exposure, a study of the electrical properties of a cylindrical sinusoidal dielectric barrier discharge is performed with and without porous material containing TiO2. The metallic inner electrode is in contact with the gas gap. First, the presence of porous material made of silica fibres coated with nanoparticles of TiO2 leads to a strong increase of the injected energy for the same applied voltage. Then the time evolution of the current amplitude distribution function (CADF) shows two different peak populations on the positive half period (when the metallic inner electrode is positive). Apart from numerous low intensity plasma filaments (around 1 mA amplitude), much larger ones exist (around 1 A). These large current amplitude peaks are responsible for 50-70% of the injected energy depending on the presence of the photocatalytic material. The influence of 900 ppm of C2H2 as well as external ultraviolet irradiation on the CADF is also reported

  4. Capabilities of the dielectric barrier discharge plasma actuator for multi-frequency excitations

    Energy Technology Data Exchange (ETDEWEB)

    Benard, N; Moreau, E [Laboratoire d' Etudes Aerodynamiques (LEA), Universite de Poitiers, ENSMA, CNRS Bld Marie et Pierre Curie, Teleport 2, 86962 Futuroscope Cedex (France)

    2010-04-14

    Natural instability mechanisms are inherent in most laminar and turbulent flow configurations. Usually, these instabilities result in the formation of flow structures occurring at diverse spatial and time scales. An effective control requires an actuator able to bring momentum transfer over a wide range of frequencies to act on these instabilities. Promising results are expected for such control strategy because, according to stability theory, a small amplitude perturbation can be large enough to produce significant effects even at high Reynolds number. Moreover, simultaneous production of small perturbations at several frequencies can enhance or cancel non-linear interactions; this opens alternative methods for flow control. The focus of this study is to demonstrate the ability of plasma actuators to introduce flow perturbations at single and dual frequencies by simply adjusting the waveform of the voltage applied to the plasma actuator. The flows produced by a dielectric barrier discharge supplied by burst, superposition and ring modulations are described in temporal and frequential domains. The results confirm the potential of non-thermal plasma actuators to produce highly unsteady flows at single, double or multiple frequencies.

  5. Permanent hydrophilization of outer and inner surfaces of polytetrafluoroethylene tubes using ambient air plasma generated by surface dielectric barrier discharges

    Energy Technology Data Exchange (ETDEWEB)

    Pavliňák, D.; Galmiz, O.; Zemánek, M.; Brablec, A.; Čech, J.; Černák, M., E-mail: cernak@physics.muni.cz [Department of Physical Electronics, Masaryk University, Kotlarska 2, Brno 60200 (Czech Republic)

    2014-10-13

    We present an atmospheric pressure ambient air plasma technique developed for technically simple treatment of inner and/or outer surfaces of plastic tubes and other hollow dielectric bodies. It is based on surface dielectric barrier discharge generating visually diffuse plasma layers along the treated dielectric surfaces using water-solution electrodes. The observed visual uniformity and measured plasma rotational and vibrational temperatures of 333 K and 2350 K indicate that the discharge can be readily applied to material surface treatment without significant thermal effect. This is exemplified by the obtained permanent surface hydrophilization of polytetrafluoroethylene tubes related to the replacement of a high fraction (more than 80%) of the surface fluorine determined by X-ray photoelectron spectroscopy. A tentative explanation of the discharge mechanism based on high-speed camera observations and the discharge current and voltage of measurements is outlined.

  6. Filamentary and diffuse barrier discharges

    International Nuclear Information System (INIS)

    Barrier discharges, sometimes also referred to as dielectric-barrier discharges or silent discharges, are characterized by the presence of at least one insulating layer in contact with the discharge between two planar or cylindrical electrodes connected to an ac power supply. The main advantage of this type of electrical discharge is, that non-equilibrium plasma conditions in atmospheric-pressure gases can be established in an economic and reliable way. This has led to a number of important applications including industrial ozone generation, surface modification of polymers, plasma chemical vapor deposition, excitation of CO2 lasers, excimer lamps and, most recently, large-area flat plasma display panels. Depending on the application, the width of the discharge gap can range from less than 0.1 mm to about 100 mm and the applied frequency from below line frequency to several gigahertz. Typical materials used for the insulating layer (dielectric barrier) are glass, quartz, ceramics but also thin enamel or polymer layers

  7. Improved Ethanol Production from Xylose by Candida shehatae Induced by Dielectric Barrier Discharge Air Plasma

    International Nuclear Information System (INIS)

    Xylose fermentation is essential for ethanol production from lignocellulosic biomass. Exposure of the xylose-fermenting yeast Candida shehatae (C. shehatae) CICC1766 to atmospheric pressure dielectric barrier discharge (DBD) air plasma yields a clone (designated as C81015) with stability, which exhibits a higher ethanol fermentation rate from xylose, giving a maximal enhancement in ethanol production of 36.2% compared to the control (untreated). However, the biomass production of C81015 is lower than that of the control. Analysis of the NADH (nicotinamide adenine dinucleotide)- and NADPH (nicotinamide adenine dinucleotide phosphate)-linked xylose reductases and NAD+-linked xylitol dehydrogenase indicates that their activities are enhanced by 34.1%, 61.5% and 66.3%, respectively, suggesting that the activities of these three enzymes are responsible for improving ethanol fermentation in C81015 with xylose as a substrate. The results of this study show that DBD air plasma could serve as a novel and effective means of generating microbial strains that can better use xylose for ethanol fermentation

  8. Improved Ethanol Production from Xylose by Candida shehatae Induced by Dielectric Barrier Discharge Air Plasma

    Science.gov (United States)

    Chen, Huixia; Xiu, Zhilong; Bai, Fengwu

    2014-06-01

    Xylose fermentation is essential for ethanol production from lignocellulosic biomass. Exposure of the xylose-fermenting yeast Candida shehatae (C. shehatae) CICC1766 to atmospheric pressure dielectric barrier discharge (DBD) air plasma yields a clone (designated as C81015) with stability, which exhibits a higher ethanol fermentation rate from xylose, giving a maximal enhancement in ethanol production of 36.2% compared to the control (untreated). However, the biomass production of C81015 is lower than that of the control. Analysis of the NADH (nicotinamide adenine dinucleotide)- and NADPH (nicotinamide adenine dinucleotide phosphate)-linked xylose reductases and NAD+-linked xylitol dehydrogenase indicates that their activities are enhanced by 34.1%, 61.5% and 66.3%, respectively, suggesting that the activities of these three enzymes are responsible for improving ethanol fermentation in C81015 with xylose as a substrate. The results of this study show that DBD air plasma could serve as a novel and effective means of generating microbial strains that can better use xylose for ethanol fermentation.

  9. A diffuse plasma generated by bipolar nanosecond pulsed dielectric barrier discharge in nitrogen

    Science.gov (United States)

    Jia, Li; Yang, De-Zheng; Shi, Heng-Chao; Wang, Wen-Chun; Wang, Sen

    2014-05-01

    In this study, a bipolar high-voltage pulse with 20 ns rising time is employed to generate diffuse dielectric barrier discharge plasma using wire-plate electrode configuration in nitrogen at atmospheric pressure. The gas temperature of the plasma is determined by comparing the experimental and the best fitted optical emission spectra of the second positive bands of N2(C3Πu → B3 Πg, 0-2) and the first negative bands of N2+ (B2 Σu+ → X2 Σg+, 0-0). The effects of the concentration of argon and oxygen on the emission intensities of N2 (C3Πu → B3Πg, 0-0, 337.1 nm), OH (A 2Σ → X2Π, 0-0) and N2+ (B2 Σu+ → X2 Σg+, 0-0, 391.4 nm) are investigated. It is shown that the plasma gas temperature keeps almost constant with the pulse repetition rate and pulse peak voltage increasing. The emission intensities of N2 (C3Πu → B3Πg, 0-0, 337.1 nm), OH(A2Σ → X2Π, 0-0) and N2+ (B2 Σu+ → X2 Σg+, 0-0, 391.4 nm) rise with increasing the concentration of argon, but decrease with increasing the concentration of oxygen, and the influences of oxygen concentration on the emission intensities of N2(C3Πu → B3Πg, 0-0, 337.1 nm) and OH (A2Σ → X2Π, 0-0) are more greater than that on the emission intensity of N2+ (B2 Σu+ → X2 Σg+, 0-0, 391.4 nm).

  10. 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.

  11. Numerical simulation of evolution features of the atmospheric-pressure CF4 plasma generated by the pulsed dielectric barrier discharge

    Science.gov (United States)

    Pan, Jie; Li, Li; Chen, Bo; Song, Yuzhi; Zhao, Yuefeng; Xiu, Xianwu

    2016-06-01

    The atmospheric-pressure CF4 plasma has the high application potential in the field of semiconductor fabrication since it can combine the excellent capability for the CF4 plasma etching with the easy atmospheric-pressure operation. In this work, the fluid model has been carried out to numerically research evolution features of the atmospheric-pressure CF4 plasma generated by the pulsed dielectric barrier discharge. The computational results show that the averaged electron temperature dramatically increases during the rising and the falling phases of the applied voltage pulse, and then swiftly decreases. The discharge current density has the waveform of two bipolar short pulses. The electrons and CF3 + ions form the cathode sheath at the discharge duration. However, the CF3 - and F- negative ions take the place of the electrons to sustain the cathode sheath of the CF4 discharge plasma at the time interval between the two bipolar discharge pulses. During the time interval of the two adjacent applied voltage pulses the discharge region is the quasi-neutral plasma region, and meanwhile CF2 + and CF3 - are the dominated charged species. Moreover, F and CF3 maintain the relatively stable high densities and uniform axial distributions during the whole period of the applied voltage.

  12. Study of Humidity Effect on Benzene Decomposition by the Dielectric Barrier Discharge Nonthermal Plasma Reactor

    Science.gov (United States)

    Ma, Tianpeng; Zhao, Qiong; Liu, Jianqi; Zhong, Fangchuan

    2016-06-01

    The humidity effects on the benzene decomposition process were investigated by the dielectric barrier discharge (DBD) plasma reactor. The results showed that the water vapor played an important role in the benzene oxidation process. It was found that there was an optimum humidity value for the benzene removal efficiency, and at around 60% relative humidity (RH), the optimum benzene removal efficiency was achieved. At a SIE of 378 J/L, the removal efficiency was 66% at 0% RH, while the removal efficiency reached 75.3% at 60% RH and dropped to 69% at 80% RH. Furthermore, the addition of water inhibited the formation of ozone and NO2 remarkably. Both of the concentrations of ozone and NO2 decreased with increasing of the RH at the same specific input energy. At a SIE of 256 J/L, the concentrations of ozone and NO2 were 5.4 mg/L and 1791 ppm under dry conditions, whereas they were only 3.4 mg/L and 1119 ppm at 63.5% RH, respectively. Finally, the outlet gas after benzene degradation was qualitatively analyzed by FT-IR and GC-MS to determine possible intermediate byproducts. The results suggested that the byproducts in decomposition of benzene primarily consisted of phenol and substitutions of phenol. Based on these byproducts a benzene degradation mechanism was proposed. supported by National Natural Science Foundation of China (Nos. 11205007 and 11205029)

  13. On the use of pulsed Dielectric Barrier Discharges to control the gas-phase composition of atmospheric pressure air plasmas

    International Nuclear Information System (INIS)

    We presents results obtained from the numerical simulation of the gas-phase chemical kinetics in atmospheric pressure air non-equilibrium plasmas. In particular we have addressed the effect of pulsed operation mode of a plane dielectric barrier discharge. It was conjectured that the large difference in the time scales involved in the fast dissociation of oxygen molecules in plasma and their subsequent reactions to produce ozone and nitrogen oxides, makes the presence of a continuously repeated plasma production unnecessary and a waste of electrical power and thus efficiency. In order to test such suggestion we have performed a numerical study of the composition and the temporal evolution of the gas-phase of atmospheric pressure air non-equilibrium plasmas. Comparison with experimental findings in a dielectric barrier discharge with an electrode configuration symmetrical and almost ideally plane is briefly addressed too, using plasma diagnostics to extract the properties of the single micro-discharges and a sensor to measure the concentration of ozone produced by the plasma

  14. Removal of priority pollutants from water by means of dielectric barrier discharge atmospheric plasma.

    Science.gov (United States)

    Hijosa-Valsero, María; Molina, Ricardo; Schikora, Hendrik; Müller, Michael; Bayona, Josep M

    2013-11-15

    Two different nonthermal plasma reactors at atmospheric pressure were assessed for the removal of organic micropollutants (atrazine, chlorfenvinfos, 2,4-dibromophenol, and lindane) from aqueous solutions (1-5 mg L(-1)) at laboratory scale. Both devices were dielectric barrier discharge (DBD) reactors; one was a conventional batch reactor (R1) and the other a coaxial thin-falling-water-film reactor (R2). A first-order degradation kinetics was proposed for both experiments. The kinetic constants (k) were slightly faster in R1 (0.534 min(-1) for atrazine; 0.567 min(-1) for chlorfenvinfos; 0.802 min(-1) for 2,4-dibromophenol; 0.389 min(-1) for lindane) than in R2 (0.104 min(-1) for atrazine; 0.523 min(-1) for chlorfenvinfos; 0.273 min(-1) for 2,4-dibromophenol; 0.294 min(-1) for lindane). However, energy efficiencies were about one order of magnitude higher in R2 (89 mg kW(-1) h(-1) for atrazine; 447 mg kW(-1) h(-1) for c hlorfenvinfos; 47 mg kW(-1) h(-1) for 2,4-dibromophenol; 50 mg kW(-1) h(-1) for lindane) than in R1. Degradation by -products of all four compounds were identified in R1. As expected, when the plasma treatment (R1) was applied to industrial wastewater spiked with atrazine or lindane, micropollutant removal was also achieved, although at a lower rate than with aqueous solutions (k = 0.117 min(-1) for atrazine; k = 0.061 min(-1) for lindane). PMID:24121639

  15. In situ measurements of OH radicals in dielectric barrier discharge plasmas with cw-cavity ring-down spectroscopy

    International Nuclear Information System (INIS)

    An apparatus of continuous wave cavity ring-down spectroscopy (cw-CRDS) has been constructed with the noise (RMS) equivalent absorption 3 x 10-9 cm-1. In situ quantitative measurements of OH radicals in dielectric barrier discharge (DBD) plasmas at low pressure using cw-CRDS are described. The influence of discharge voltage and pressure on number density of OH has been investigated. Results show that the OH production increases at low pressure with increasing discharge pressure; however, the number density of OH decreases due to electron attachment of H2O at higher pressure. The number density of OH radical increases with increasing discharge voltage and discharge frequency because of the increase of electron density and electron energy. (authors)

  16. Forcing mechanisms of dielectric barrier discharge plasma actuators at carrier frequency of 625 Hz

    NARCIS (Netherlands)

    Kotsonis, M.; Ghaemi, S.

    2011-01-01

    The forcing behavior of a dielectric barrier discharge (DBD) actuator is investigated experimentally using a time-resolved particle image velocimetry (PIV) system in conjunction with a phase shifting technique. The spatio-temporal evolution of the induced flowfield is accurately captured within one

  17. Surface and adhesive properties of antibacterial medical-grade PVC modified by barrier discharge plasma

    Czech Academy of Sciences Publication Activity Database

    Novák, I.; Lehocký, M.; Asadinezhad, A.; Chodák, I.; Špírková, Milena; Popelka, A.; Števiar, M.

    Praha : Ústav makromolekulární chemie AV ČR, v. v. i., 2010. s. 50. ISBN 978-80-85009-64-4. [Česko-slovenská konference POLYMERY 2010 /6./. 04.10.2010-07.10.2010, Liblice] Institutional research plan: CEZ:AV0Z40500505 Keywords : barrier discharge * surface modification Subject RIV: CD - Macromolecular Chemistry

  18. Dielectric barrier discharge plasma atomizer for hydride generation atomic absorption spectrometry-Performance evaluation for selenium

    Czech Academy of Sciences Publication Activity Database

    Duben, Ondřej; Boušek, J.; Dědina, Jiří; Kratzer, Jan

    2015-01-01

    Roč. 111, SEP (2015), s. 57-63. ISSN 0584-8547 Grant ostatní: GA AV ČR(CZ) M200311202 Institutional support: RVO:68081715 Keywords : dielectric barrier discharge * hydride generation-atomic absorption spectrometry * selenium Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.176, year: 2014

  19. Dielectric barrier discharge plasma atomizer for hydride generation atomic absorption spectrometry—Performance evaluation for selenium

    International Nuclear Information System (INIS)

    Atomization of selenium hydride in a quartz dielectric barrier discharge (DBD) atomizer was optimized and its performance was compared to that of the externally heated quartz multiatomizer. Argon was found as the best DBD discharge gas employing a flow rate of 75 ml min−1 Ar while the DBD power was optimized at 14 W. The detection limits reached 0.24 ng ml−1 Se in the DBD and 0.15 ng ml−1 Se in the multiatomizer. The tolerance of DBD to interferences is even better than with the multiatomizer. - Highlights: • SeH2 atomization in a dielectric barrier discharge (DBD) was optimized for AAS. • Atomizer performance was compared for DBD and externally heated quartz atomizer. • Detection limits were quantified and interferences were studied in both atomizers. • Atomization efficiency in the DBD was estimated

  20. Development of a diffuse air-argon plasma source using a dielectric-barrier discharge at atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Tang Jie; Jiang Weiman; Zhao Wei; Wang Yishan; Li Shibo; Wang Haojing [State Key Laboratory of Transient Optics and Photonics, Xi' an Institute of Optics and Precision Mechanics of CAS, Xi' an 710119 (China); Duan Yixiang [State Key Laboratory of Transient Optics and Photonics, Xi' an Institute of Optics and Precision Mechanics of CAS, Xi' an 710119 (China); Research Center of Analytical Instrumentation, Sichuan University, Chengdu 610064 (China)

    2013-01-21

    A stable diffuse large-volume air plasma source was developed by using argon-induced dielectric-barrier discharges at atmospheric pressure. This plasma source can be operated in a filamentary discharge with the average areal power density of 0.27 W/cm{sup 2} and the gas temperature of 315{+-}3 K. Spatial measurement of emission spectrum and temperature indicates that this plasma is uniform in the central region along the transverse direction. It is also found that the formation of diffuse air plasma mainly lies in the creation of sufficient seed electrons by the Penning effect through collisions between two argon or nitrogen metastables at low electric fields.

  1. Electrical Characterization of Dielectric Barrier Discharge in Atmospheric Air for Plasma Production Aiming for Improving Seed Germination

    International Nuclear Information System (INIS)

    A Dielectric Barrier Discharge (DBD) reactor has been developed aiming for improving seed germination. This DBD reactor consists of two 3-inch stainless steel planar electrodes with mylar sheets as dielectric barriers. An adjustable frequency AC high voltage power supply is then connected to the DBD reactor in order to generate plasma. The gas gap of DBD can be varied up to 3 mm when operating in atmospheric air. The electrical characterization of this DBD such as power, current, etc., together with optical emission characterization of plasma generated with this DBD will be presented. This information will be essential toward a development in order for applying plasma to small seeds, such as tomato, rice, chili, etc. to improve seed germination as inspired by the work of Bozena Sera et al (IEEE Trans. Plasma Sci., vol. 38, no. 10, p.2963).

  2. Effect of duty-cycles on the air plasma gas-phase of dielectric barrier discharges

    Science.gov (United States)

    Barni, R.; Biganzoli, I.; Dell'Orto, E. C.; Riccardi, C.

    2015-10-01

    An experimental investigation concerning the effects of a duty-cycle in the supply of a dielectric barrier discharge in atmospheric pressure air has been performed. Electrical characteristics of the discharge have been measured, focusing mainly on the statistical properties of the current filaments and on dielectric surface charging, both affected by the frequent repetition of breakdown imposed by the duty-cycle. Information on the gas-phase composition was gathered too. In particular, a strong enhancement in the ozone formation rate is observed when suitable long pauses separate the active discharge phases. A simulation of the chemical kinetics in the gas-phase, based on a simplified discharge modeling, is briefly described in order to shed light on the observed increase in ozone production. The effect of a duty-cycle on surface modification of polymeric films in order to increase their wettability has been investigated too.

  3. Spatial and temporal evolution of microdischarges in Surface Dielectric Barrier Discharges for aeronautical applications plasmas

    International Nuclear Information System (INIS)

    Surface Dielectric Barrier Discharges have been proposed long ago as a tool to improve aerodynamics and flow performances. Such electrical discharges could be employed to energize the gas phase and to induce flows. The discharge itself consists of a large number of repetitions of single electric current pulses, with short duration and limited spatial extension filling the region near electrodes. The connection between such macroscopic effect and the properties of the single microdischarge events has been investigated. In particular we have measured the direction and the velocity of propagation of the ionization wave during the different phases of the voltage cycle. Light collected from different parts of the gap arrives at a photomultiplier tube with a delay proportional to the velocity of the ionization wave. The measured propagation velocity was estimated as about 220 km/s in the so called backward discharge phase

  4. Removal of priority pollutants from water by means of dielectric barrier discharge atmospheric plasma

    Energy Technology Data Exchange (ETDEWEB)

    Hijosa-Valsero, María, E-mail: mhijv@unileon.es [Instituto de Diagnóstico Ambiental y Estudios del Agua (IDAEA), CID, CSIC, C/Jordi Girona 18-26, E-08034 Barcelona (Spain); Molina, Ricardo, E-mail: ricardo.molina@cid.csic.es [Instituto de Química Avanzada de Cataluña (IQAC), CID, CSIC, C/Jordi Girona 18-26, E-08034 Barcelona (Spain); Schikora, Hendrik, E-mail: hendrik.schikora@igb.fraunhofer.de [Fraunhofer IGB, Nobelstraße 12, 70569 Stuttgart (Germany); Müller, Michael, E-mail: michael.mueller@igb.fraunhofer.de [Fraunhofer IGB, Nobelstraße 12, 70569 Stuttgart (Germany); Bayona, Josep M., E-mail: josep.bayona@cid.csic.es [Instituto de Diagnóstico Ambiental y Estudios del Agua (IDAEA), CID, CSIC, C/Jordi Girona 18-26, E-08034 Barcelona (Spain)

    2013-11-15

    Highlights: • DBD plasma reactors were used to remove pollutants from aqueous solutions. • Atrazine, chlorfenvinfos, 2,4-dibromophenol and lindane were studied. • First-order degradation kinetics were observed for all the compounds. • Degradation by-products were identified by GC–MS. • Treatment efficiencies were lower in industrial wastewater than in pure water. -- Abstract: Two different nonthermal plasma reactors at atmospheric pressure were assessed for the removal of organic micropollutants (atrazine, chlorfenvinfos, 2,4-dibromophenol, and lindane) from aqueous solutions (1–5 mg L{sup −1}) at laboratory scale. Both devices were dielectric barrier discharge (DBD) reactors; one was a conventional batch reactor (R1) and the other a coaxial thin-falling-water-film reactor (R2). A first-order degradation kinetics was proposed for both experiments. The kinetic constants (k) were slightly faster in R1 (0.534 min{sup −1} for atrazine; 0.567 min{sup −1} for chlorfenvinfos; 0.802 min{sup −1} for 2,4-dibromophenol; 0.389 min{sup −1} for lindane) than in R2 (0.104 min{sup −1} for atrazine; 0.523 min{sup −1} for chlorfenvinfos; 0.273 min{sup −1} for 2,4-dibromophenol; 0.294 min{sup −1} for lindane). However, energy efficiencies were about one order of magnitude higher in R2 (89 mg kW{sup −1} h{sup −1} for atrazine; 447 mg kW{sup −1} h{sup −1} for chlorfenvinfos; 47 mg kW{sup −1} h{sup −1} for 2,4-dibromophenol; 50 mg kW{sup −1} h{sup −1} for lindane) than in R1. Degradation by-products of all four compounds were identified in R1. As expected, when the plasma treatment (R1) was applied to industrial wastewater spiked with atrazine or lindane, micropollutant removal was also achieved, although at a lower rate than with aqueous solutions (k = 0.117 min{sup −1} for atrazine; k = 0.061 min{sup −1} for lindane)

  5. Dielectric barrier discharge plasma atomizer for hydride generation atomic absorption spectrometry-Performance evaluation for selenium

    Science.gov (United States)

    Duben, Ondřej; Boušek, Jaroslav; Dědina, Jiří; Kratzer, Jan

    2015-09-01

    Atomization of selenium hydride in a quartz dielectric barrier discharge (DBD) atomizer was optimized and its performance was compared to that of the externally heated quartz multiatomizer. Argon was found as the best DBD discharge gas employing a flow rate of 75 ml min- 1 Ar while the DBD power was optimized at 14 W. The detection limits reached 0.24 ng ml- 1 Se in the DBD and 0.15 ng ml- 1 Se in the multiatomizer. The tolerance of DBD to interferences is even better than with the multiatomizer.

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

    Science.gov (United States)

    Dahle, S.

    2015-10-01

    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.

  7. 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.

  8. Ellipsometric investigations during plasma cleaning: Comparison between low-pressure rf-plasma and barrier discharge at atmospheric pressure

    International Nuclear Information System (INIS)

    The removal of hydrocarbon containing compounds using a barrier discharge at atmospheric pressure (air) as well as a capacitively coupled 13.56 MHz low-pressure rf-discharge has been examined. Al plates, Si-wafer and Al coated Si-wafer served as substrate materials. In the rf-discharge, power and gas pressure were varied. Argon, oxygen, and hydrogen were used as process gases. In the barrier discharge, power variation was investigated. Spectroscopic ellipsometry was used to determine thickness and optical properties of the contamination. The removal of the contamination layers was observed by means of in-situ kinetic ellipsometry. In the rf-discharge the thickness of the lubricant decreases linearly with the treatment time. The determined removal rates per discharge power are 0.1 nm/Ws for O2 and about 0.01 nm/Ws for Ar and H2. In the barrier discharge the etching rate decreases about exponentially with treatment time. This is due to a beginning polymerization shown by the increase of the optical constants of the lubricant. The etching rate reaches values up to 0. 1 mm/Ws. After the removal of the lubricant the thickness of the surface oxide increases significantly. (author)

  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. Effect of particle size on silver nanoparticle deposition onto dielectric barrier discharge (DBD) plasma functionalized polyamide fabric

    OpenAIRE

    Vu, Nguyen Khanh; Zille, Andrea; Oliveira, F. R.; Carneiro, Noémia; Souto, A. Pedro

    2013-01-01

    The effect on the deposition of three different size silver nanoparticles (AgNPs) onto a polyamide 6,6 (PA) fabric pre-treated using air dielectric barrier discharge (DBD) plasma was investigated. The SEM, EDS, and XPS analysis confirm that the smaller is the diameter of AgNPs, the higher the amount of adsorbed NPs on the PA. The DBD treatment on PA induces a threefold increase in Ag adsorption. The result confirms a dual effect on the wettability of the plasma treated PA substrate. AgNPs sli...

  11. Preferential killing of human lung cancer cell lines with mitochondrial dysfunction by nonthermal dielectric barrier discharge plasma

    OpenAIRE

    Panngom, K; Baik, K Y; Nam, M K; Han, J. H.; Rhim, H; Choi, E. H.

    2013-01-01

    The distinctive cellular and mitochondrial dysfunctions of two human lung cancer cell lines (H460 and HCC1588) from two human lung normal cell lines (MRC5 and L132) have been studied by dielectric barrier discharge (DBD) plasma treatment. This cytotoxicity is exposure time-dependent, which is strongly mediated by the large amount of H2O2 and NOx in culture media generated by DBD nonthermal plasma. It is found that the cell number of lung cancer cells has been reduced more than that of the lun...

  12. Self-organization of single filaments and diffusive plasmas during a single pulse in dielectric-barrier discharges

    International Nuclear Information System (INIS)

    Self-organization of filaments in dielectric-barrier discharges (DBDs) probably has many origins. However, the dominant cause is proposed to be the accumulation of charge on the surfaces of the bounding dielectrics that reinforces successive discharge pulses to occur at the same locations. A secondary cause is the electrostatic repulsion of individual plasma filaments. Self-organization typically develops over many discharge pulses. In this paper, we discuss the results of a computational investigation of plasma filaments in overvoltage DBDs that, under select conditions, display self-organized patterns (SOPs) of plasma density during a single discharge pulse. (Overvoltage refers to the rapid application of a voltage in excess of the quasi-dc breakdown voltage.) The origin of the SOPs is a synergistic relationship between the speed of the surface-ionization waves that propagate along each dielectric and the rate at which avalanche occurs across the gap. For our test conditions, SOPs were not observed at lower voltages and gradually formed at higher voltages. The same conditions that result in SOPs, i.e. the application of an overvoltage, also produce more diffuse discharges. A transition from a single narrow filament to a more diffuse structure was observed as overvoltage was approached. The sensitivity of SOPs to the orientation and permittivity of the bounding dielectrics is discussed. (paper)

  13. Theoretical analysis of ion kinetic energies and DLC film deposition by CH4+Ar (He) dielectric barrier discharge plasmas

    Institute of Scientific and Technical Information of China (English)

    Liu Yan-Hong; Zhang Jia-Liang; Ma Teng-Cai; Li Jian; Liu Dong-Ping

    2007-01-01

    The kinetic energy of ions in dielectric barrier discharge plasmas are analysed theoretically using the model of binary collisions between ions and gas molecules. Langevin equation for ions in other gases, Blanc law for ions in mixed gases, and the two-temperature model for ions at higher reduced field are used to determine the ion mobility. The kinetic energies of ions in CH4 + Ar(He) dielectric barrier discharge plasma at a fixed total gas pressure and various Ar (He)concentrations are calculated. It is found that with increasing Ar (He) concentration in CH4 + Ar (He) from 20% to 83%,the CH4+ kinetic energy increases from 69.6 (43.9) to 92.1 (128.5)eV, while the Ar+ (He+) kinetic energy decreases from 97 (145.2) to 78.8 (75.5)eV. The increase of CH4+ kinetic energy is responsible for the increase of hardness of diamond-like carbon films deposited by CH4 + Ar (He) dielectric barrier discharge without bias voltage over substrates.

  14. Treatment surfaces with atomic oxygen excited in dielectric barrier discharge plasma of O2 admixed to N2

    Directory of Open Access Journals (Sweden)

    E. V. Shun'ko

    2012-06-01

    Full Text Available This paper describes the increase in surface energy of substrates by their treatment with gas composition generated in plasmas of DBD (Dielectric Barrier Discharge in O2 admixed with N2. Operating gas dissociation and excitation was occurred in plasmas developed in two types of reactors of capacitively-coupled dielectric barrier configurations: coaxial cylindrical, and flat rectangular. The coaxial cylindrical type comprised an inner cylindrical electrode encapsulated in a ceramic sheath installed coaxially inside a cylindrical ceramic (quartz tube passing through an annular outer electrode. Components of the flat rectangular type were a flat ceramic tube of a narrow rectangular cross section supplied with two flat electrodes mounted against one another outside of the long parallel walls of this tube. The operating gas, mixture of N2 and O2, was flowing in a completely insulated discharge gap formed between insulated electrodes of the devices with an average velocity of gas inlet of about 7 to 9 m/s. Dielectric barrier discharge plasma was excited in the operating gaps with a bipolar pulse voltage of about 6 kV for 2 ms at 50 kHz repetition rate applied to the electrodes of the coaxial device, and of about 14 kV for 7 ms at 30 kHz repetition rate for the flat linear device. A lifetime of excited to the 2s22p4(1S0 state in DBD plasma and streaming to the surfaces with a gas flow atomic oxygen, responsible presumably for treating surfaces, exceeded 10 ms in certain cases, that simplified its separation from DBD plasma and delivery to substrates. As it was found in particular, surfaces of glass and some of polymers revealed significant enhancement in wettability after treatment.

  15. Plasma treatment of poly(dimethylsiloxane) surfaces using a compact atmospheric pressure dielectric barrier discharge device for adhesion improvement

    Science.gov (United States)

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

    2016-02-01

    Results of the treatment of poly(dimethylsiloxane) (PDMS) surfaces using novel atmospheric pressure pulsed dielectric barrier discharge plasmas are presented. Different gases (argon, helium, nitrogen) as well as their mixtures with water vapor were compared in terms of the improvement of adhesion between two PDMS samples after processing by plasma. The plasma was characterized by optical emission spectroscopy to identify the emitting species and determine the plasma temperatures. For all the gases studied, plasma processing resulted in increase of adhesion between PDMS samples if long exposure time (larger than 150 s) is applied. However, for very short treatment times (20 plasma pulses, total processing time about 3 s) the highest efficiency was found for helium plasmas. Water contact angles at PDMS surfaces as function of plasma processing time was analyzed. Atomic force microscopy analysis was performed to show reduction in the surface roughness after plasma treatment, which is likely to be the responsible for increase of the surface contact area and thus the adhesion between two PDMS surfaces. The role of the two mechanisms in the improvement of adhesion (enhanced wettability and changes in the surface morphology), for different time scales, is discussed. Interestingly, for the minimum processing time (20 plasma pulses), the improvement in adhesion and reduction of surface roughness are observed although the changes in the water contact angle are insignificant.

  16. Improvement of Dielectric Barrier Discharge Plasma Reactor for Ozone Generation by Electrode Shape

    Science.gov (United States)

    Shimizu, Masaki; Sato, Tohru; Kato, Shoji; Mukaigawa, Seiji; Takaki, Koichi; Fujiwara, Tamiya

    An effect of electrode shape on ozone generation in dielectric barrier discharge reactor is described in this article. Three different shape electrodes were employed as ground electrodes. A plane electrode is 6 cm in width, and 20 cm in length. A trench electrode has large number of knife-edge rails. A multipoint electrode has large number of four-sided pyramid projections on the plane. A high voltage plane electrode is covered with 0.5 mm thickness alumina layer worked as dielectric barrier. The experimental results show that the breakdown for the multipoint electrode occurs at 7.0 kVpp. This value is lower than 8.4 kVpp that is the breakdown voltage of the plane electrode. The ozone yield increases from 80 g/kWh to 130 g/kWh by changing the electrode shape from the plane to the multipoint. The ozone generation efficiency decreased with increase of the ozone concentration.

  17. Determination of the HO2 radical in dielectric barrier discharge plasmas using near-infrared cavity ring-down spectroscopy

    International Nuclear Information System (INIS)

    The hydroperoxyl radical (HO2) plays an important role in combustion systems, atmospheric chemistry and the removal of air pollutants by non-thermal plasmas. This work reports the determination of the hydroperoxyl radical in dielectric barrier discharge plasmas via near-infrared continuous wave cavity ring-down spectroscopy. HO2 radicals were observed in discharges of HCHO/O2/H2O/N2 mixtures around 6625.7 cm-1 in the first H-OO stretching overtone, (2, 0, 0)-(0, 0, 0), of its ground electronic state X-tilde2A''. At certain discharge conditions (ac frequency of 5 kHz, peak-to-peak voltage of 6.5 kV, 1900 ppm HCHO, 20% O2, 3.5% H2O in N2, Ptotal = 30 Torr), HO2 radical concentration was determined to be 1.0 x 1013 molecules cm-3. The temporary evolution of HO2 concentration was obtained using the 'time window' method. The effects of oxygen concentration, water concentration, the discharge voltage and discharge gas pressure on the concentration of HO2 radicals have been investigated. The detection limit of our setup for the HO2 radical is ∼1 x 1011 molecules cm-3

  18. Direct plasma NOx reduction using single surface dielectric barrier discharge

    OpenAIRE

    Kroushawi, Feisal; Stamate, Eugen

    2014-01-01

    NOx reduction using direct atmospheric barrier discharge in air-NO mixture at different voltages and flow rates is inversigated. Reduction rate of 80% is achieved at 3.18 W/cm2 power density and gas mixture of 20 slm air and 0.006 slm NO. The ozone for NO reduction is produced by a honeycomb structured DBD with a total surface of 12.56 cm2. The reduction process is investigated by FTIR spectroscopy, chemiluminsecence, mass spectrometry and optical emission spectroscopy.

  19. Direct plasma NOx reduction using single surface dielectric barrier discharge

    DEFF Research Database (Denmark)

    Kroushawi, Feisal; Stamate, Eugen

    2014-01-01

    NOx reduction using direct atmospheric barrier discharge in air-NO mixture at different voltages and flow rates is inversigated. Reduction rate of 80% is achieved at 3.18 W/cm2 power density and gas mixture of 20 slm air and 0.006 slm NO. The ozone for NO reduction is produced by a honeycomb...... structured DBD with a total surface of 12.56 cm2. The reduction process is investigated by FTIR spectroscopy, chemiluminsecence, mass spectrometry and optical emission spectroscopy....

  20. Effects and Mechanism of Atmospheric-Pressure Dielectric Barrier Discharge Cold Plasma on Lactate Dehydrogenase (LDH) Enzyme

    Science.gov (United States)

    Zhang, Hao; Xu, Zimu; Shen, Jie; Li, Xu; Ding, Lili; Ma, Jie; Lan, Yan; Xia, Weidong; Cheng, Cheng; Sun, Qiang; Zhang, Zelong; Chu, Paul K.

    2015-05-01

    Proteins are carriers of biological functions and the effects of atmospheric-pressure non-thermal plasmas on proteins are important to applications such as sterilization and plasma-induced apoptosis of cancer cells. Herein, we report our detailed investigation of the effects of helium-oxygen non-thermal dielectric barrier discharge (DBD) plasmas on the inactivation of lactate dehydrogenase (LDH) enzyme solutions. Circular dichroism (CD) and dynamic light scattering (DLS) indicate that the loss of activity stems from plasma-induced modification of the secondary molecular structure as well as polymerization of the peptide chains. Raising the treatment intensity leads to a reduced alpha-helix content, increase in the percentage of the beta-sheet regions and random sequence, as well as gradually decreasing LDH activity. However, the structure of the LDH plasma-treated for 300 seconds exhibits a recovery trend after storage for 24 h and its activity also increases slightly. By comparing direct and indirect plasma treatments, plasma-induced LDH inactivation can be attributed to reactive species (RS) in the plasma, especially ones with a long lifetime including hydrogen peroxide, ozone, and nitrate ion which play the major role in the alteration of the macromolecular structure and molecular diameter in lieu of heat, UV radiation, and charged particles.

  1. Microsecond-pulsed dielectric barrier discharge plasma stimulation of tissue macrophages for treatment of peripheral vascular disease

    Energy Technology Data Exchange (ETDEWEB)

    Miller, V., E-mail: vmiller@coe.drexel.edu; Lin, A.; Brettschneider, J.; Fridman, G.; Fridman, A. [AJ Drexel Plasma Institute, Drexel University, Camden, New Jersey 08103 (United States); Kako, F.; Gabunia, K.; Kelemen, S.; Autieri, M. [Department of Physiology, Independence Blue Cross Cardiovascular Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania 19140 (United States)

    2015-12-15

    Angiogenesis is the formation of new blood vessels from pre-existing vessels and normally occurs during the process of inflammatory reactions, wound healing, tissue repair, and restoration of blood flow after injury or insult. Stimulation of angiogenesis is a promising and an important step in the treatment of peripheral artery disease. Reactive oxygen species have been shown to be involved in stimulation of this process. For this reason, we have developed and validated a non-equilibrium atmospheric temperature and pressure short-pulsed dielectric barrier discharge plasma system, which can non-destructively generate reactive oxygen species and other active species at the surface of the tissue being treated. We show that this plasma treatment stimulates the production of vascular endothelial growth factor, matrix metalloproteinase-9, and CXCL 1 that in turn induces angiogenesis in mouse aortic rings in vitro. This effect may be mediated by the direct effect of plasma generated reactive oxygen species on tissue.

  2. Microsecond-pulsed dielectric barrier discharge plasma stimulation of tissue macrophages for treatment of peripheral vascular disease

    International Nuclear Information System (INIS)

    Angiogenesis is the formation of new blood vessels from pre-existing vessels and normally occurs during the process of inflammatory reactions, wound healing, tissue repair, and restoration of blood flow after injury or insult. Stimulation of angiogenesis is a promising and an important step in the treatment of peripheral artery disease. Reactive oxygen species have been shown to be involved in stimulation of this process. For this reason, we have developed and validated a non-equilibrium atmospheric temperature and pressure short-pulsed dielectric barrier discharge plasma system, which can non-destructively generate reactive oxygen species and other active species at the surface of the tissue being treated. We show that this plasma treatment stimulates the production of vascular endothelial growth factor, matrix metalloproteinase-9, and CXCL 1 that in turn induces angiogenesis in mouse aortic rings in vitro. This effect may be mediated by the direct effect of plasma generated reactive oxygen species on tissue

  3. Microsecond-pulsed dielectric barrier discharge plasma stimulation of tissue macrophages for treatment of peripheral vascular disease

    Science.gov (United States)

    Miller, V.; Lin, A.; Kako, F.; Gabunia, K.; Kelemen, S.; Brettschneider, J.; Fridman, G.; Fridman, A.; Autieri, M.

    2015-12-01

    Angiogenesis is the formation of new blood vessels from pre-existing vessels and normally occurs during the process of inflammatory reactions, wound healing, tissue repair, and restoration of blood flow after injury or insult. Stimulation of angiogenesis is a promising and an important step in the treatment of peripheral artery disease. Reactive oxygen species have been shown to be involved in stimulation of this process. For this reason, we have developed and validated a non-equilibrium atmospheric temperature and pressure short-pulsed dielectric barrier discharge plasma system, which can non-destructively generate reactive oxygen species and other active species at the surface of the tissue being treated. We show that this plasma treatment stimulates the production of vascular endothelial growth factor, matrix metalloproteinase-9, and CXCL 1 that in turn induces angiogenesis in mouse aortic rings in vitro. This effect may be mediated by the direct effect of plasma generated reactive oxygen species on tissue.

  4. Electric wind produced by surface plasma actuators: a new dielectric barrier discharge based on a three-electrode geometry

    International Nuclear Information System (INIS)

    Active flow control is a rapidly developing topic because the associated industrial applications are of immense importance, particularly for aeronautics. Among all the flow control methods, such as the use of mechanical flaps or wall jets, plasma-based devices are very promising devices. The main advantages of such systems are their robustness, their simplicity, their low-power consumption and that they allow a real-time control at high frequency. This paper deals with an experimental study about the electric wind produced by a surface discharge based on a three-electrode geometry. This new device is composed of a typical two-electrode surface barrier discharge excited by an AC high voltage, plus a third electrode at which a DC high voltage is applied in order to extend the discharge region and to accelerate the ion drift velocity. In the first part the electrical current of these different surface discharges is presented and discussed. This shows that the current behaviour depends on the DC component polarity. The second part is dedicated to analysing the electric wind characteristics through Schlieren visualizations and to measuring its time-averaged velocity with a Pitot tube sensor. The results show that an excitation of the electrodes with an AC voltage plus a positive DC component can significantly modify the topology of the electric wind produced by a single DBD. In practice, this DC component allows us to increase the value of the maximum induced velocity (up to +150% at a few centimetres downstream of the discharge) and the plasma extension, to enhance the depression occurring above the discharge region and to increase the discharge-induced mass flow rate (up to +100%), without increasing the electrical power consumption

  5. Methane conversion into higher hydrocarbons with dielectric barrier discharge micro-plasma reactor

    Institute of Scientific and Technical Information of China (English)

    Baowei; Wang; Wenjuan; Yan; Wenjie; Ge; Xiaofei; Duan

    2013-01-01

    We reported a coaxial,micro-dielectric barrier discharge(micro-DBD)reactor and a conventional DBD reactor for the direct conversion of methane into higher hydrocarbons at atmospheric pressure.The effects of input power,residence time,discharge gap and external electrode length were investigated for methane conversion and product selectivity.We found the conversion of methane in a micro-DBD reactor was higher than that in a conventional DBD reactor.And at an input power of 25.0 W,the conversion of methane and the total C2+C3 selectivity reached 25.10% and 80.27%,respectively,with a micro-DBD reactor of 0.4 mm discharge gap.Finally,a nonlinear multiple regression model was used to study the correlations between both methane conversion and product selectivity and various system variables.The calculated data were obtained using SPSS 12.0 software.The regression analysis illustrated the correlations between system variables and both methane conversion and product selectivity.

  6. 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. PMID:27388420

  7. Dielectric Barrier Discharge Plasma-Induced Photocatalysis and Ozonation for the Treatment of Wastewater

    Science.gov (United States)

    Mok, Young Sun; Jo, Jin-Oh; Lee, Heon-Ju

    2008-02-01

    The physicochemical processes of dielectric barrier discharge (DBD) such as in-situ formation of chemically active species and emission of ultraviolet (UV)/visible light were utilized for the treatment of a simulated wastewater formed with Acid Red 4 as the model organic contaminant. The chemically active species (mostly ozone) produced in the DBD reactor were well distributed in the wastewater using a porous gas diffuser, thereby increasing the gas-liquid contact area. For the purpose of making the best use of the light emission, a titanium oxide-based photocatalyst was incorporated in the wastewater treating system. The experimental parameters chosen were the voltage applied to the DBD reactor, the initial pH of the wastewater, and the concentration of hydrogen peroxide added to the wastewater. The results have clearly shown that the present system capable of degrading organic contaminants in two ways (photocatalysis and ozonation) may be a promising wastewater treatment technology.

  8. Dielectric Barrier Discharge Plasma-Induced Photocatalysis and Ozonation for the Treatment of Wastewater

    Institute of Scientific and Technical Information of China (English)

    MOK Young Sun; JO Jin-Oh; LEE Heon-Ju

    2008-01-01

    The physicochemical processes of dielectric barrier discharge (DBD) such as in-situ formation of chemically active species and emission of ultraviolet (UV)/visible light were utilized for the treatment of a simulated wastewater formed with Acid Red 4 as the model organic contaminant. The chemically active species (mostly ozone) produced in the DBD reactor were well distributed in the wastewater using a porous gas diffuser, thereby increasing the gas-liquid contact area. For the purpose of making the best use of the light emission, a titanium oxide-based photocatalyst was incorporated in the wastewater treating system. The experimental parameters chosen were the voltage applied to the DBD reactor, the initial pH of the wastewater, and the concentration of hydrogen peroxide added to the wastewater. The results have clearly shown that the present system capable of degrading organic contaminants in two ways (photocatalysis and ozonation) may be a promising wastewater treatment technology.

  9. Dielectric Barrier Discharge Plasma-Induced Photocatalysis and Ozonation for the Treatment of Wastewater

    International Nuclear Information System (INIS)

    The physicochemical processes of dielectric barrier discharge (DBD) such as in-situ formation of chemically active species and emission of ultraviolet (UV)/visible light were utilized for the treatment of a simulated wastewater formed with Acid Red 4 as the model organic contaminant. The chemically active species (mostly ozone) produced in the DBD reactor were well distributed in the wastewater using a porous gas diffuser, thereby increasing the gas-liquid contact area. For the purpose of making the best use of the light emission, a titanium oxide-based photocatalyst was incorporated in the wastewater treating system. The experimental parameters chosen were the voltage applied to the DBD reactor, the initial pH of the wastewater, and the concentration of hydrogen peroxide added to the wastewater. The results have clearly shown that the present system capable of degrading organic contaminants in two ways (photocatalysis and ozonation) may be a promising wastewater treatment technology.

  10. The Study of the Effects of Surface Dielectric Barrier Discharge Low Temperature Plasma Products on Spring and Winter Wheat Germination

    Directory of Open Access Journals (Sweden)

    A.V. Lazukin

    2015-04-01

    Full Text Available The use of ion-plasma technologies for treatment of seeds of different crop plants is particularly important for regions that exist in environment of risk farming. This is due to the lack of supplies in the treatment, durability, reliability and performance of these technologies. However, the mixed results of studies obtained for different species and varieties of seeds, make it necessary to detail compare the effects of the low-temperature plasma products for different cultures. This paper presents the results of experimental studies of the effects of plasma products of surface dielectric barrier discharge on the germination of spring and winter wheat. It has been shown that irrespective of time and the exposure intensity laboratory germination of spring wheat seeds reduced of 74% in the control group to 52% of the treated seeds, while the germination of wheat seeds is not reduced even at a relatively long exposure (20 min. The modes of treatment (3 min, 2.1-2.4 kV at which germination of winter wheat seeds increase from 81% in the control group to 87% of the treated seeds have been selected. Resistance of winter wheat seed germination to the product of the discharge plasma can be used to form the conditions for safe suppression of a variety of pathogenic organisms on the surface of seeds.

  11. Electro-Catalysis System for Biodiesel Synthesis from Palm Oil over Dielectric-Barrier Discharge Plasma Reactor

    Directory of Open Access Journals (Sweden)

    Istadi Istadi

    2014-07-01

    Full Text Available Biodiesel synthesis reaction routes from palm oil using plasma electro-catalysis process over Dielectric-Barrier Discharge (DBD plasma reactor were studied. The study was focused on finding possible reaction mechanism route during plasma electro-catalysis process. The prediction was performed based on the changes of Gas Chromatography Mass Spectrometer (GC-MS and Fourier Transform Infra Red (FT-IR analyses to the biodiesel products with respect to time length of plasma treatment. It was found that main reaction mechanism occurred in the plasma electro-catalysis system was non-thermal pyrolysis rather than transesterification. The main reactions within the plasma treatment were due to collision between high energetic electrons (supplied from high voltage power supply through high voltage electrode and the reaction mixtures. The high energetic electrons affected the electrons pair of covalent bonding to be excited or dissociated even ionized at higher energy. Therefore, this plasma electro-catalysis system was promising for biodiesel synthesis from vegetable oils due to only very short time reaction was needed, even no need a catalyst, no soap formation, and no glycerol by-product. This system could produce fatty acid methyl ester yield of 75.65% at 120 seconds and other possible chemicals, such as alkynes, alkanes, esters, carboxylic acid, and aldehydes. However, during the plasma process, the reaction mechanisms were still difficult to be controlled due the action of available high energetic electrons. The advanced studies on how to control the reaction mechanism selectively in the plasma electro-catalysis will be published elsewhere. © 2014 BCREC UNDIP. All rights reservedReceived: 23rd January 2014; Revised: 20th March 2014; Accepted: 23rd March 2014[How to Cite: Istadi, I., Yudhistira, A.D., Anggoro, D.D., Buchori, L. (2014. Electro-Catalysis System for Biodiesel Synthesis from Palm Oil over Dielectric-Barrier Discharge Plasma Reactor

  12. Consequences of unburned hydrocarbons on microstreamer dynamics and chemistry during plasma remediation of NOx using dielectric barrier discharges

    International Nuclear Information System (INIS)

    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

  13. Formaldehyde removal from gas streams by means of NaNO{sub 2} dielectric barrier discharge plasma

    Energy Technology Data Exchange (ETDEWEB)

    Liang Wenjun, E-mail: liangwenj1978@hotmail.com [College of Environmental and Energy Engineering, Beijing University of Technology, No. 100 Ping Le Yuan, Chao Yang District, Beijing 100124 (China); Li Jian; Li Jingxin; Zhu Tao; Jin Yuquan [College of Environmental and Energy Engineering, Beijing University of Technology, No. 100 Ping Le Yuan, Chao Yang District, Beijing 100124 (China)

    2010-03-15

    Destruction of formaldehyde by means of NaNO{sub 2} 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 NaNO{sub 2} 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 NaNO{sub 2} DBD plasma significantly and enhanced with increasing SED distinctly. More amount of NaNO{sub 2} 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{sub 2} and H{sub 2}O.

  14. 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...

  15. Optical emission characteristics of medium- to high-pressure N2 dielectric barrier discharge plasmas during surface modification of polymers

    International Nuclear Information System (INIS)

    The authors measured the band spectra (first and second positive systems) of the nitrogen molecule by optical emission spectroscopy with an aim to understand the mechanism of surface processing by medium- to high-pressure dielectric barrier discharge (DBD) plasmas. The experimentally measured and calculated spectra were compared to determine the vibrational and rotational temperatures of the N2 (C3Πu) state in the generated plasmas. The authors generated the N2 DBD plasmas at a driving frequency of 1-7 kHz and a discharge pressure of 20-105 Pa for the surface modification of a polyethylene terephthalate (PET) sample. It was found that the vibrational temperature was greatly affected by the N2 pressure while the rotational temperature remained constant in the N2 pressure range of 20-105 Pa. The emission intensity of N2 first positive system (B3Π→A3Σ) rapidly decreased at an increasing N2 pressure due to the collisional relaxation process of the B3Π state with N2 molecules. The N2+(B2Σu+→X2Σg+) radiative transition was observed in the low-pressure DBD plasmas, which was attributed to the direct electron impact ionization of N2 molecules. The surface characterizations of treated PET samples by contact angle measurement and atomic force microscopy indicate that the low-pressure N2 DBD plasma is an effective method for the surface modification of polymers. Analysis indicates the plasma characteristics such as electron temperature and ion energy are mainly dependent on the N2 pressure, which turn to determine the surface properties of treated PET samples.

  16. Effects of Environmental Humidity and Temperature on Sterilization Efficiency of Dielectric Barrier Discharge Plasmas in Atmospheric Pressure Air

    Science.gov (United States)

    Kikuchi, Yusuke; Miyamae, Masanori; Nagata, Masayoshi; Fukumoto, Naoyuki

    2011-01-01

    The inactivation of Bacillus atrophaeus spores by a dielectric barrier discharge (DBD) plasma in atmospheric humid air was investigated in order to develop a low-temperature, low-cost, and high-speed plasma sterilization technique. The biological indicators covered with a Tyvek sheet were set just outside the DBD plasma region, where air temperature and humidity as a discharge gas were precisely controlled by an environmental test chamber. The results show that the inactivation of B. atrophaeus spores was found to be dependent strongly on humidity, and was completed within 15 min at a relative humidity of 90% and a temperature of 30 °C. The treatment time for sterilization is shorter than those of conventional sterilization methods using ethylene oxide gas and dry heat treatment. The inactivation rates depend on not only relative humidity but also temperature, so that water content in air could determine the generation of reactive species such as hydroxyl radicals that are effective for the inactivation of B. atrophaeus spores.

  17. Discharge Characteristics of an Atmospheric Pressure Argon Plasma Jet Generated with Screw Ring-Ring Electrodes in Surface Dielectric Barrier Discharge

    International Nuclear Information System (INIS)

    An atmospheric-pressure argon plasma jet with screw ring-ring electrodes in surface dielectric barrier discharge is generated by a sinusoidal excitation voltage at 8 kHz. The discharge characteristics, such as rotational and vibrational temperature of nitrogen, electronic excitation temperature, oxygen atomic density, nitrogen molecular density, and average electron density, are estimated. It is found that the rotational temperature of nitrogen is in the range of 352 ∼ 392 K by comparing the simulated spectrum with the measured spectrum at the C3Πu → B3Πg(Δv = −2) band transition, the electronic excitation temperature is found to be in the range of 3127 ∼ 3230 K by using the Boltzmann plot method, the oxygen atomic and nitrogen molecular density are of the order of magnitude of 1016 cm−3 by the actinometry method, and the average electron density is of the order of magnitude of 1012 cm−3 by the energy balance equation. Besides, the effective power, conduction, and displacement current are measured during the discharge. (low temperature plasma)

  18. Functionalization of Hydrogen-free Diamond-like Carbon Films using Open-air Dielectric Barrier Discharge Atmospheric Plasma Treatments

    Energy Technology Data Exchange (ETDEWEB)

    Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Instituto de Materiales de Madrid, C.S.I.C., Cantoblanco, 28049 Madrid, Spain; Instituto de Quimica-Fisica" Rocasolano" C.S.I.C., 28006 Madrid, Spain; Mahasarakham University, Mahasarakham 44150, Thailand; CASTI, CNR-INFM Regional Laboratory, L' Aquila 67100, Italy; SUNY Upstate Medical University, Syracuse, NY 13210, USA; Endrino, Jose; Endrino, J. L.; Marco, J. F.; Poolcharuansin, P.; Phani, A.R.; Allen, M.; Albella, J. M.; Anders, A.

    2007-12-28

    A dielectric barrier discharge (DBD) technique has been employed to produce uniform atmospheric plasmas of He and N2 gas mixtures in open air in order to functionalize the surface of filtered-arc deposited hydrogen-free diamond-like carbon (DLC) films. XPS measurements were carried out on both untreated and He/N2 DBD plasma treated DLC surfaces. Chemical states of the C 1s and N 1s peaks were collected and used to characterize the surface bonds. Contact angle measurements were also used to record the short- and long-term variations in wettability of treated and untreated DLC. In addition, cell viability tests were performed to determine the influence of various He/N2 atmospheric plasma treatments on the attachment of osteoblast MC3T3 cells. Current evidence shows the feasibility of atmospheric plasmas in producing long-lasting variations in the surface bonding and surface energy of hydrogen-free DLC and consequently the potential for this technique in the functionalization of DLC coated devices.

  19. Influence of ionic liquid and ionic salt on protein against the reactive species generated using dielectric barrier discharge plasma

    Science.gov (United States)

    Attri, Pankaj; Sarinont, Thapanut; Kim, Minsup; Amano, Takaaki; Koga, Kazunori; Cho, Art E.; Ha Choi, Eun; Shiratani, Masaharu

    2015-12-01

    The presence of salts in biological solution can affect the activity of the reactive species (RS) generated by plasma, and so they can also have an influence on the plasma-induced sterilization. In this work, we assess the influence that diethylammonium dihydrogen phosphate (DEAP), an ionic liquid (IL), and sodium chloride (NaCl), an ionic salt (IS), have on the structural changes in hemoglobin (Hb) in the presence of RS generated using dielectric barrier discharge (DBD) plasma in the presence of various gases [O2, N2, Ar, He, NO (10%) + N2 and Air]. We carry out fluorescence spectroscopy to verify the generation of •OH with or without the presence of DEAP IL and IS, and we use electron spin resonance (ESR) to check the generation of H• and •OH. In addition, we verified the structural changes in the Hb structure after treatment with DBD in presence and absence of IL and IS. We then assessed the structural stability of the Hb in the presence of IL and IS by using molecular dynamic (MD) simulations. Our results indicate that the IL has a strong effect on the conservation of the Hb structure relative to that of IS against RS generated by plasma.

  20. Dielectric barrier discharges used for the conversion of greenhouse gases: modeling the plasma chemistry by fluid simulations

    Energy Technology Data Exchange (ETDEWEB)

    De Bie, Christophe; Martens, Tom; Bogaerts, Annemie [Research Group PLASMANT, Department of Chemistry, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk (Belgium); Van Dijk, Jan [Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands); Paulussen, Sabine; Verheyde, Bert [Flemish Institute for Technological Research (VITO), Boeretang 200, 2400 Mol (Belgium); Corthals, Steven, E-mail: annemie.bogaerts@ua.ac.b [Centre for Surface Chemistry and Catalysis, K. U. Leuven, Kasteelpark Arenberg 23, 3001 Heverlee (Belgium)

    2011-04-15

    The conversion of methane to value-added chemicals and fuels is considered to be one of the challenges of the 21st century. In this paper we study, by means of fluid modeling, the conversion of methane to higher hydrocarbons or oxygenates by partial oxidation with CO{sub 2} or O{sub 2} in a dielectric barrier discharge. Sixty-nine different plasma species (electrons, ions, molecules, radicals) are included in the model, as well as a comprehensive set of chemical reactions. The calculation results presented in this paper include the conversion of the reactants and the yields of the reaction products as a function of residence time in the reactor, for different gas mixing ratios. Syngas (i.e. H{sub 2} + CO) and higher hydrocarbons (C{sub 2}H{sub x}) are typically found to be important reaction products.

  1. Dependence of the oxidation properties of a dielectric barrier discharge in air on the plasma and gas temperatures

    International Nuclear Information System (INIS)

    Investigations were carried out on atmospheric pressure dielectric barrier discharges, in a point-to-plane geometry energized with ac or pulsed high voltage power supplies of variable frequency (from 3.5 to 50 kHz). Electrical / chemical coupling processes on the one hand, and thermal / chemical coupling processes on the other hand were studied through ozone production. Correlations based on these properties were established, using emission spectroscopy measurements for the determination of the plasma gas temperature. The temperature in the active gas volume, i.e. the volume in which the ozone three body formation reaction takes place, was evaluated thanks to comparisons between experimental data and calculations based on a simple model for the ozone formation. (author)

  2. Dielectric barrier discharges used for the conversion of greenhouse gases: modeling the plasma chemistry by fluid simulations

    International Nuclear Information System (INIS)

    The conversion of methane to value-added chemicals and fuels is considered to be one of the challenges of the 21st century. In this paper we study, by means of fluid modeling, the conversion of methane to higher hydrocarbons or oxygenates by partial oxidation with CO2 or O2 in a dielectric barrier discharge. Sixty-nine different plasma species (electrons, ions, molecules, radicals) are included in the model, as well as a comprehensive set of chemical reactions. The calculation results presented in this paper include the conversion of the reactants and the yields of the reaction products as a function of residence time in the reactor, for different gas mixing ratios. Syngas (i.e. H2 + CO) and higher hydrocarbons (C2Hx) are typically found to be important reaction products.

  3. The relation between doses or post-plasma time points and apoptosis of leukemia cells induced by dielectric barrier discharge plasma

    Science.gov (United States)

    Wang, Chao; Zhang, Haixia; Xue, Zhixiao; Yin, Huijuan; Niu, Qing; Chen, Hongli

    2015-12-01

    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.

  4. Characterization and Properties of Electroless Nickel Plated Poly (ethylene terephthalate) Nonwoven Fabric Enhanced by Dielectric Barrier Discharge Plasma Pretreatment

    Science.gov (United States)

    Geng, Yamin; Lu, Canhui; Liang, Mei; Zhang, Wei

    2010-12-01

    In order to develop a more economical pretreatment method for electroless nickel plating, a dielectric barrier discharge (DBD) plasma at atmospheric pressure was used to improve the hydrophilicity and adhesion of poly (ethylene terephthalate) (PET) nonwoven fabric. The properties of the PET nonwoven fabric including its liquid absorptive capacity (WA), aging behavior, surface chemical composition, morphology of the surface, adhesion strength, surface electrical resistivity and electromagnetic interference (EMI)- shielding effectiveness (SE) were studied. The liquid absorptive capacity (WA) increased due to the incorporation of oxygen-containing and nitrogen-containing functional groups on the surface of PET nonwoven fabric after DBD air-plasma treatment. The surface morphology of the nonwoven fibers became rougher after plasma treatment. Therefore, the surface was more prone to absorb tin sensitizer and palladium catalyst to form an active layer for the deposition of electroless nickel. SEM and X-ray diffraction (XRD) measurements indicated that a uniform coating of nickel was formed on the PET nonwoven fabric. The average EMI-SE of Ni-plating of PET nonwoven fabric maintained a relatively stable value (38.2 dB to 37.3 dB) in a frequency range of 50 MHz to 1500 MHz. It is concluded that DBD is feasible for pretreatment of nonwoven fabric for electroless nickel plating to prepare functional material with good EMI-SE properties.

  5. Characterization and Properties of Electroless Nickel Plated Poly (ethylene terephthalate) Nonwoven Fabric Enhanced by Dielectric Barrier Discharge Plasma Pretreatment

    International Nuclear Information System (INIS)

    In order to develop a more economical pretreatment method for electroless nickel plating, a dielectric barrier discharge (DBD) plasma at atmospheric pressure was used to improve the hydrophilicity and adhesion of poly (ethylene terephthalate) (PET) nonwoven fabric. The properties of the PET nonwoven fabric including its liquid absorptive capacity (WA), aging behavior, surface chemical composition, morphology of the surface, adhesion strength, surface electrical resistivity and electromagnetic interference (EMI)- shielding effectiveness (SE) were studied. The liquid absorptive capacity (WA) increased due to the incorporation of oxygen-containing and nitrogen-containing functional groups on the surface of PET nonwoven fabric after DBD air-plasma treatment. The surface morphology of the nonwoven fibers became rougher after plasma treatment. Therefore, the surface was more prone to absorb tin sensitizer and palladium catalyst to form an active layer for the deposition of electroless nickel. SEM and X-ray diffraction (XRD) measurements indicated that a uniform coating of nickel was formed on the PET nonwoven fabric. The average EMI-SE of Ni-plating of PET nonwoven fabric maintained a relatively stable value (38.2 dB to 37.3 dB) in a frequency range of 50 MHz to 1500 MHz. It is concluded that DBD is feasible for pretreatment of nonwoven fabric for electroless nickel plating to prepare functional material with good EMI-SE properties.

  6. Partial Oxidation of Methane with Sol-Gel Fe/Hf/YSZ Catalyst in Dielectric Barrier Discharge: Catalyst Activation by Plasma

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A 1% Fe-30% Hf over yttria-stabilized zirconia catalyst in combination with novel plasma-assisted activation techniques for a direct partial oxidation of methane to methanol was tested using dielectric barrier discharge plasma at ambient temperature and atmospheric pressure. However, instead of methanol, the reaction products were dominated by H2,CO, CO2, C2, and H2O. A catalytically activated plasma process increased the production of methanol compared with a noncatalytic plasma process. The maximum selectivity of methanol production was achieved using a catalyst that was treated at higher applied power.

  7. Atmospheric-pressure plasma CVD of TiO{sub 2} photocatalytic films using surface dielectric barrier discharge

    Energy Technology Data Exchange (ETDEWEB)

    Di Lanbo; Li Xiaosong; Shi Chuan; Xu Yong; Zhao Dezhi; Zhu Aimin, E-mail: amzhu@dlut.edu.c [Laboratory of Plasma Physical Chemistry, Dalian University of Technology, Dalian 116024 (China)

    2009-02-07

    Surface dielectric barrier discharge (DBD) was used for atmospheric-pressure plasma CVD of TiO{sub 2} films from TiCl{sub 4} and O{sub 2} for the first time. Under this experiment, the deposition rate was estimated at 22 nm min{sup -1} by scanning electron microscope observation and the as-deposited TiO{sub 2} films were amorphous as evidenced by Raman analysis. The photocatalytic application of TiO{sub 2} films in removing HCHO from simulated air was examined in a continuous flow reactor. The TiO{sub 2} films after calcination at 350 or 450 deg. C were notably photocatalytically active for complete oxidation of formaldehyde to an innocuous product (CO{sub 2}), which was consistent with the results of Raman analysis. Using the TiO{sub 2} films, an extremely harmful by-product, CO, was not detected from photocatalytic oxidation of HCHO in a simulated air stream. (fast track communication)

  8. Plasma density enhancement in atmospheric-pressure dielectric-barrier discharges by high-voltage nanosecond pulse in the pulse-on period: a PIC simulation

    Energy Technology Data Exchange (ETDEWEB)

    Sang Chaofeng; Sun Jizhong; Wang Dezhen, E-mail: wangdez@dlut.edu.c [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)

    2010-02-03

    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.

  9. Plasma density enhancement in atmospheric-pressure dielectric-barrier discharges by high-voltage nanosecond pulse in the pulse-on period: a PIC simulation

    International Nuclear Information System (INIS)

    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.

  10. 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.

  11. Interaction between a surface dielectric barrier discharge and transonic airflows

    OpenAIRE

    Pavón, Samantha; Ott, Peter; Thome, John Richard

    2009-01-01

    The use of plasmas in aerodynamics has become a recent topic of interest. The potentialities of different types of plasmas are being investigated for low velocity and high velocity flow control, as well as for plasma-assisted combustion. Dielectric barrier discharges (DBDs) are good candidates since the transition of the glow or filamentary discharge to an arc is prevented by the dielectric barrier. Moreover, surface DBDs allow to ionize the gas very close to the dielectric surface and can be...

  12. Interaction between a surface dielectric barrier discharge and transonic airflows

    OpenAIRE

    Pavón, Samantha

    2008-01-01

    The use of plasmas in aerodynamics has become a recent topic of interest. The potentialities of different types of plasmas are being investigated for low velocity and high velocity flow control, as well as for plasma-assisted combustion. Dielectric barrier discharges (DBDs) are good candidates since the transition of the glow or filamentary discharge to an arc is prevented by the dielectric barrier. Moreover, surface DBDs allow to ionize the gas very close to the dielectric surface and can be...

  13. Discharge expansion in barrier discharge arrangements at low applied voltages

    International Nuclear Information System (INIS)

    This study evaluates the spatial expansion of barrier discharges (BDs) in oxygen, carbon dioxide, synthetic air, and helium at atmospheric pressure. Despite being confined in narrow gas channels, the BD plasma only partially covers the available discharge area at low applied voltages as was experimentally observed. This is important for homogeneous surface treatment. The appearance of local discharge zones in the plasma development results in a variation of the capacitive behaviour of the equivalent electric circuit as a function of the applied voltage. This transient behaviour of the apparent dielectric capacitance is therefore investigated for various discharge areas and different gas compositions. Furthermore, a semi-empirical model describing the expansion behaviour is proposed and validated by means of the obtained experimental data. The results clearly show that a three times higher voltage excess is required for oxygen-containing gases compared with helium in order to develop full plasma expansion. For the discharge areas considered, the size of the available electrode plays a minor role in the plasma expansion process.

  14. A New Approach to Plasma CVD of TiO2 Photocatalyst on γ-Al2O3 Pellet Filled in Dielectric Barrier Discharges at Atmospheric Pressure

    Institute of Scientific and Technical Information of China (English)

    朱爱民; 聂龙辉; 张秀玲; 石川; 宋志民; 徐勇

    2004-01-01

    A supported TiO2/γ-Al2O3 photocatalyst has been prepared by γ-Al2O3 pellet-filled dielectric barrier discharges induced plasma CVD at atmospheric pressure and room temperature.The TiO2/γ-Al2O3 photocatalyst exhibits higher photocatalytic activity than Degussa P25, and much higher photocatalytic activity than that prepared by thermal CVD.

  15. Atmospheric pressure plasma produced inside a closed package by a dielectric barrier discharge in Ar/CO2 for bacterial inactivation of biological samples

    DEFF Research Database (Denmark)

    Chiper, Alina Silvia; Chen, Weifeng; Mejlholm, Ole;

    2011-01-01

    The generation and evaluation of a dielectric barrier discharge produced inside a closed package made of a commercially available packaging film and filled with gas mixtures of Ar/CO2 at atmospheric pressure is reported. The discharge parameters were analysed by electrical measurements and optical...... emission spectroscopy in two modes of operation: trapped gas atmosphere and flowing gas atmosphere. Gas temperature was estimated using the OH(A–X) emission spectrum and the rotational temperature reached a saturation level after a few minutes of plasma running. The rotational temperature was almost three...

  16. Plasma-promoted partial oxidation of methane to syngas over α-alumina supported nickel catalyst in dielectric-barrier discharge

    International Nuclear Information System (INIS)

    The combination of a dielectric barrier discharge and an α-alumina supported nickel catalyst for the synthesis gas (H2 and CO) production was studied. Two processes - partial oxidation of methane and combined steam-oxygen reforming of methane were investigated. It was found that the presence of a catalyst in the discharge zone enhanced plasma selectivity. The methane conversion and product distribution were functions of oxygen concentration in the feed gas and the input power energy. Selectivity to hydrogen as high as 90% was obtained. (author)

  17. Dielectric barrier discharge-based plasma actuator operation in artificial atmospheres for validation of modeling and simulation

    Science.gov (United States)

    Mangina, R. S.; Enloe, C. L.; Font, G. I.

    2015-11-01

    We present an experimental case study of time-resolved force production by an aerodynamic plasma actuator immersed in various mixtures of electropositive (N2) and electronegative gases (O2 and SF6) at atmospheric pressure using a fixed AC high-voltage input of 16 kV peak amplitude at 200 Hz frequency. We have observed distinct changes in the discharge structures during both negative- and positive-going voltage half-cycles, with corresponding variations in the actuator's force production: a ratio of 4:1 in the impulse produced by the negative-going half-cycle of the discharge among the various gas mixtures we explored, 2:1 in the impulse produced by the positive-going half-cycle, and cases in which the negative-going half-cycle dominates force production (by a ratio of 1.5:1), where the half-cycles produce identical force levels, and where the positive-going half cycle dominates (by a ratio of 1:5). We also present time-resolved experimental evidence for the first time that shows electrons do play a significant role in the momentum coupling to surrounding neutrals during the negative going voltage half-cycle of the N2 discharge. We show that there is sufficient macroscopic variation in the plasma that the predictions of numerical models at the microscopic level can be validated even though the plasma itself cannot be measured directly on those spatial and temporal scales.

  18. Measurement of ion density in an atmospheric pressure argon with pin-to-plate dielectric barrier discharge by resonance of plasma radiation

    International Nuclear Information System (INIS)

    The measurements of the ion densities in the atmospheric AC barrier corona argon discharge are carried out by receiving and analyzing the frequencies of the electromagnetic radiation emitted from the plasma. An auxiliary excitation source composed of a pin-to-pin discharge system is introduced to excite the oscillations of the main discharge. To analyze the resonance mechanism, a complemented model based on a one-dimensional description of forced vibrations is given. Calculations indicate that Ar2+ is the dominant ion (∼89% in number density). By analyzing resonance frequencies, the ion densities of Ar2+ are in the order of 1019∼1020m−3 and increase slowly as the applied voltage increases

  19. The first experiments on dielectric barrier discharge under atmospheric pressure

    International Nuclear Information System (INIS)

    In order to obtain uniform and stable discharge plasma in atmospheric pressure, dielectric barrier discharge experiments were carried out. Main purpose is to examine the applicability of dielectric barrier discharge to production processes of semi-conductors. LSIs and flat display panels. In the experiments, at first, quite stable and uniform discharge was obtained at atmospheric pressure. Effects of applied voltage and frequency on plasma uniformity were studied. Improvement of discharge uniformity by introducing gas flow of helium or nitrogen between the discharge gap was observed. Finally, surface cleaning effect of the present plasma was confirmed by observing contact angle of liquid droplet. At least for cleaning process, possibility of application as process plasma was suggested

  20. Effect of multiple pulses on the plasma chemistry during the remediation of NOx using dielectric barrier discharges

    International Nuclear Information System (INIS)

    Dielectric barrier discharges (DBDs) are being investigated to remediate NOx from atmospheric gas streams. The interaction of species generated during previous pulses of repetitively pulsed devices, such as DBDs, make their operation fundamentally different from single pulse operation. To investigate these effects, the reaction chemistry of multiple pulses during NOx remediation was modelled. Reactions between radicals produced during a pulse with the products from previous pulses produce significantly different end products. For example, approximately 10 ppm of methyl nitrate (CH3ONO2) was obtained by multiple pulsing whereas less than 1 ppm of it was produced with single discharge formats. Multiple pulsing has also been found to be more efficient for NOx remediation. W-values for NOx remediation decreased from 240 eV for a single pulse (58 J l-1) to 185 eV when the same energy was distributed over 20 pulses. (author)

  1. Dielectric barrier discharge plasma treatment on E. coli: Influence of CH4/N2, O2, N2/O2, N2, and Ar gases

    International Nuclear Information System (INIS)

    Atmospheric pressure dielectric barrier discharge (DBD) plasma has been employed on Gram-negative bacteria, Escherichia coli BL21. Treatment was carried out using plasma generated with different compositions of gases: CH4/N2 (1:2), O2, N2/O2 (1:1), N2, and Ar, and by varying plasma power and treatment time. E. coli cells were exposed under the DBD plasma in triplicates, and their surviving numbers were observed in terms of colony forming units. It has been observed that the CH4/N2 plasma exhibits relatively higher sterilization property toward E. coli compared to plasma generated by using O2, N2/O2, N2, and Ar gas mixtures. The time to kill up to 90% of the initial population of the E. coli cells was found to be about 2-3 min for CH4/N2 and O2 gas mixture DBD plasma. A prolongation of treatment time and an increase in the dissipated power significantly improved the E. coli killing efficiency of the atmospheric pressure DBD plasma.

  2. Efficacy of different carrier gases for barrier discharge plasma generation compared to chlorhexidine on the survival of Pseudomonas aeruginosa embedded in biofilm in vitro.

    Science.gov (United States)

    Matthes, R; Hübner, N-O; Bender, C; Koban, I; Horn, S; Bekeschus, S; Weltmann, K-D; Kocher, T; Kramer, A; Assadian, O

    2014-01-01

    Because of its antimicrobial properties, nonthermal plasma could serve as an alternative to chemical antisepsis in wound treatment. Therefore, this study investigated the inactivation of biofilm-embedded Pseudomonas aeruginosa SG81 by a surface barrier-discharged (SBD) plasma for 30, 60, 150 and 300 s. In order to optimize the efficacy of the plasma, different carrier gases (argon, argon admixed with 1% oxygen, and argon with increased humidity up to approx. 80%) were tested and compared against 0.1% chlorhexidine digluconate (CHG) exposure for 600 s. The antimicrobial efficacy was determined by calculating the difference between the numbers of colony-forming units (CFU) of treated and untreated biofilms. Living bacteria were distinguished from dead by fluorescent staining and confocal laser scanning microscopy. Both SBD plasmas and CHG showed significant antimicrobial effects compared to the untreated control. However, plasma treatment led to a higher antimicrobial reduction (argon plasma 4.9 log10 CFU/cm(2), argon with admixed oxygen 3 log10 CFU/cm(2), and with increased gas humidity 2.7 log10 CFU/cm(2) after 300 s) compared to CHG. In conclusion, SBD plasma is suitable as an alternative to CHG for inactivation of Pseudomonas aeruginosa embedded in biofilm. Further development of SBD plasma sources and research on the role of carrier gases and humidity may allow their clinical application for wound management in the future. PMID:24434726

  3. Experimental Investigation of Separation Control on a NACA0024 Airfoil using Stationary and Non-Stationary AC-Dielectric Barrier Discharge Plasma Actuator

    Directory of Open Access Journals (Sweden)

    Hossein Parishani

    2016-01-01

    Full Text Available An experimental study of stationary and non-stationary dielectric barrier discharge (DBD plasma actuator is presented to control the flow around a NACA0024 airfoil. First, an induced air velocity of ~5 m/s is generated on a flat plate in still air using an AC-DBD actuator to find the optimal setup of the actuator (voltage, frequency, electrode width and gap size. Using the same actuator in the optimal position/setup on a NACA0024 airfoil at Reynolds number of 0.48×106, we are able to increase the stall angle of the airfoil to 18º, compared to 16º in no-actuator state. Furthermore, during the plasma actuation, the lift is increased by up to 5%. We show that non-stationary actuation, while yielding a performance similar to stationary actuation, leads to a considerable reduction of ~51% in plasma power consumption.

  4. Experimental Investigation of “Why an AC Dielectric Barrier Discharge Plasma Actuator is Preferred to DC Corona Wind Actuator in Boundary Layer Flow Control?”

    OpenAIRE

    Gholam reza Tathiri; Esmaeil Esmaeilzadeh; seyyed mahdi mirsajedi; hossein mahdavy moghaddam

    2014-01-01

    In this paper, characteristics of the flow induced in the boundary layer by an AC-Dielectric Barrier Discharge (DBD) plasma actuator are compared against those of a DC-corona wind actuator. This is achieved by visualization of the induced flow using smoke injection and measuring the horizontal induced velocity. Our measurements show that the maximum induced velocity of an AC-DBD actuator is about one order of magnitude larger than that of a DC-corona actuator. For an AC-DBD actuator, the indu...

  5. Experimental Investigation of Separation Control on a NACA0024 Airfoil using Stationary and Non-Stationary AC-Dielectric Barrier Discharge Plasma Actuator

    OpenAIRE

    Hossein Parishani

    2016-01-01

    An experimental study of stationary and non-stationary dielectric barrier discharge (DBD) plasma actuator is presented to control the flow around a NACA0024 airfoil. First, an induced air velocity of ~5 m/s is generated on a flat plate in still air using an AC-DBD actuator to find the optimal setup of the actuator (voltage, frequency, electrode width and gap size). Using the same actuator in the optimal position/setup on a NACA0024 airfoil at Reynolds number of 0.48×106, we are ab...

  6. Dielectric barrier discharge-based plasma actuator operation in artificial atmospheres for validation of modeling and simulation

    International Nuclear Information System (INIS)

    We present an experimental case study of time-resolved force production by an aerodynamic plasma actuator immersed in various mixtures of electropositive (N2) and electronegative gases (O2 and SF6) at atmospheric pressure using a fixed AC high-voltage input of 16 kV peak amplitude at 200 Hz frequency. We have observed distinct changes in the discharge structures during both negative- and positive-going voltage half-cycles, with corresponding variations in the actuator's force production: a ratio of 4:1 in the impulse produced by the negative-going half-cycle of the discharge among the various gas mixtures we explored, 2:1 in the impulse produced by the positive-going half-cycle, and cases in which the negative-going half-cycle dominates force production (by a ratio of 1.5:1), where the half-cycles produce identical force levels, and where the positive-going half cycle dominates (by a ratio of 1:5). We also present time-resolved experimental evidence for the first time that shows electrons do play a significant role in the momentum coupling to surrounding neutrals during the negative going voltage half-cycle of the N2 discharge. We show that there is sufficient macroscopic variation in the plasma that the predictions of numerical models at the microscopic level can be validated even though the plasma itself cannot be measured directly on those spatial and temporal scales

  7. 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.

  8. Integrated coaxial-hollow micro dielectric-barrier-discharges for a large-area plasma source operating at around atmospheric pressure

    International Nuclear Information System (INIS)

    An integrated structure of coaxial-hollow micro dielectric-barrier-discharges has been developed by stacking two metal meshes covered with insulating material. The test panel has an effective area of 50 mm diameter in which hundreds of hollow structures are assembled with a unit hollow area of 0.2 x 1.7 mm2. He or N2 was used as the discharge gas in the pressure range from 20 to 100 kPa and the firing voltage was less than 2 kV, even at the maximum pressure. The intensity of each microdischarge was observed to be uniform over the whole area throughout the pressure range, and its time evolution during one discharge pulse was analysed through two-dimensional microscopic observation with a gated CCD camera. In a gas flow regime through the coaxial hollow structures, several significant changes of the discharge properties were observed, such as impurity reduction, decrease in discharge voltage and cooling of the neutral gas. The fundamental plasma parameters were measured using a single probe in the downstream region of microdischarges using an auxiliary flat electrode set apart from the mesh electrode plane. The occurrence of an extended glow with a length of some millimetres was observed in He but not in N2. The electron density derived by the probe data in He at 100 kPa was ∼3 x 1011 cm-3, suggesting a value of more than 1012 cm-3 in the active microdischarge region

  9. Nanolayer biofilm coated on magnetic nanoparticles by using a dielectric barrier discharge glow plasma fluidized bed for immobilizing an antimicrobial peptide

    International Nuclear Information System (INIS)

    Using the monomer of acrylic acid and the novel technique of using a dielectric barrier discharge glow plasma fluidized bed (GPFB), a nanolayer biofilm of polyacrylic acid (PAA) was uniformly coated on the surface of magnetic nickel nanoparticles (NPs). Transmission electron microscopy, Fourier transform infrared spectroscopy, and x-ray photoelectron spectroscopy, etc, were used to characterize the modified NPs. The thickness of the biofilm was about 2 nm when the NPs were treated using the GPFB once, and the discharging conditions affected the density of the carboxyl group obviously. The PAA acting as an adhesion layer was used to immobilize the antimicrobial peptide LL-37, to kill the bacteria of Escherichia coli (E. coli), and the results indicated that the modified nickel NPs immobilizing a certain concentration of LL-37 could kill the bacteria effectively.

  10. 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.

  11. Filament Discharge Phenomena in Fingerprint Acquisition by Dielectric Barrier Discharge

    Institute of Scientific and Technical Information of China (English)

    WENG Ming; XU Weijun; LIU Qiang

    2007-01-01

    In this paper, the dielectric barrier discharge fingerprint acquisition technique is introduced. The filament discharge phenomena were observed in the process of fingerprint acquisition. The filament discharge reduced the quality of fingerprint images. Obviously, it was necessary to eliminate streamer discharges in order to get good fingerprint images. The streamer discharge was considered to be the cause of the filament discharge in the experiment. The relationship between the critical electric field and the discharge gap was calculated with the Raether's model of streamer discharge. The calculated results and our experiment proved that it would be difficult for the streamer discharge to occur when the discharge gap was narrow. With a narrow discharge gap, the discharge was homogeneous, and the fingerprint images were clear and large in area. The images obtained in the experiment are very suitable for fingerprint identification as they contain more information.

  12. Determination of the HO{sub 2} radical in dielectric barrier discharge plasmas using near-infrared cavity ring-down spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Liu Zhongwei; Xu Yong; Yang Xuefeng; Zhu Aimin; Zhao Guoli; Wang Weiguo [Laboratory of Plasma Physical Chemistry, PO Box 288, Dalian University of Technology, Dalian 116024 (China)], E-mail: yongxu@dlut.edu.cn

    2008-02-21

    The hydroperoxyl radical (HO{sub 2}) plays an important role in combustion systems, atmospheric chemistry and the removal of air pollutants by non-thermal plasmas. This work reports the determination of the hydroperoxyl radical in dielectric barrier discharge plasmas via near-infrared continuous wave cavity ring-down spectroscopy. HO{sub 2} radicals were observed in discharges of HCHO/O{sub 2}/H{sub 2}O/N{sub 2} mixtures around 6625.7 cm{sup -1} in the first H-OO stretching overtone, (2, 0, 0)-(0, 0, 0), of its ground electronic state X-tilde{sup 2}A''. At certain discharge conditions (ac frequency of 5 kHz, peak-to-peak voltage of 6.5 kV, 1900 ppm HCHO, 20% O{sub 2}, 3.5% H{sub 2}O in N{sub 2}, P{sub total} = 30 Torr), HO{sub 2} radical concentration was determined to be 1.0 x 10{sup 13} molecules cm{sup -3}. The temporary evolution of HO{sub 2} concentration was obtained using the 'time window' method. The effects of oxygen concentration, water concentration, the discharge voltage and discharge gas pressure on the concentration of HO{sub 2} radicals have been investigated. The detection limit of our setup for the HO{sub 2} radical is {approx}1 x 10{sup 11} molecules cm{sup -3}.

  13. The interaction between plasma filaments in dielectric barrier discharges and liquid covered wounds: electric fields delivered to model platelets and cells

    International Nuclear Information System (INIS)

    The treatment of wounds by atmospheric pressure plasmas in the context of plasma medicine typically proceeds through a liquid layer covering exposed cells. The wounds and their liquid covering often have irregular shapes with electrical properties (i.e. conductivity and permittivities) that may differ not only from wound-to-wound but also for a single wound as healing proceeds. The differing shapes and electrical properties extend into the liquid within the wound that typically contains cellular materials such as blood platelets. The plasma, wound, liquid and intra-liquid cellular components represent an interacting system of mutual dependence. In this paper, we discuss the results from a computational investigation of the treatment of small, liquid-covered wounds by filamentary dielectric barrier discharges. The sizes of the wounds are of the order of the plasma filaments and the liquid within the wound, an approximation of blood serum, contains idealized blood platelets. We find that the electrical properties of a wound can have significant effects on the spreading of the plasma on its surface by virtue of the deformation of the vacuum electric fields due to the shape, the effective capacitance of the wound and the discontinuities in electrical permittivity. This in turn effects the penetration of the electric field to cells under the liquid. The orientation and permittivity of the platelets relative to the liquid determines the electric fields that may stimulate the platelets. (paper)

  14. Plasma texturing of multicrystalline silicon for solar cell using remote-type pin-to-plate dielectric barrier discharge

    International Nuclear Information System (INIS)

    Multicrystalline silicon (mc-Si) was etched using a pin-to-plate-type remote dielectric barrier discharge, and the effect of adding NF3 to N2 (40 slm) and O2 to N2 (40 slm)/NF3 (1 slm) on the characteristics of mc-Si etching and texturing was investigated. The addition of NF3 at flow rates up to that of N2 increased the mc-Si etch rate continuously by increasing the number of F radicals in the gas mixture. Furthermore, the addition of O2 at flow rates of up to 400 sccm to N2 (40 slm)/NF3 (1 slm) further increased the mc-Si etch rate by more than two times (749.6 nm/scan, 0.25 m min-1), as compared with that without oxygen by the further dissociation of NF3 caused by oxygen. In particular, the addition of O2 to N2/NF3 increased the surface roughness, due to the micromasking (local surface oxidation) effect and, by adding 600 sccm O2, a reflectance of 20-30% in the visible wavelength could be obtained due to the formation of optimal wave-type surface morphology.

  15. Collective phenomena in volume and surface barrier discharges

    International Nuclear Information System (INIS)

    Barrier discharges are increasingly used as a cost-effective configuration to produce non-equilibrium plasmas at atmospheric pressure. This way, copious amounts of electrons, ions, free radicals and excited species can be generated without significant heating of the background gas. In most applications the barrier is made of dielectric material. Major applications utilizing mainly dielectric barriers include ozone generation, surface cleaning and modification, polymer and textile treatment, sterilization, pollution control, CO2 lasers, excimer lamps, plasma display panels (flat TV screens). More recent research efforts are devoted to biomedical applications and to plasma actuators for flow control. Sinusoidal feeding voltages at various frequencies as well as pulsed excitation schemes are used. Volume as well as surface barrier discharges can exist in the form of filamentary, regularly patterned or diffuse, laterally homogeneous discharges. The physical effects leading to collective phenomena in volume and surface barrier discharges are discussed in detail. Special attention is paid to self-organization of current filaments and pattern formation. Major similarities of the two types of barrier discharges are elaborated.

  16. Collective phenomena in volume and surface barrier discharges

    Science.gov (United States)

    Kogelschatz, U.

    2010-11-01

    Barrier discharges are increasingly used as a cost-effective configuration to produce non-equilibrium plasmas at atmospheric pressure. This way, copious amounts of electrons, ions, free radicals and excited species can be generated without significant heating of the background gas. In most applications the barrier is made of dielectric material. Major applications utilizing mainly dielectric barriers include ozone generation, surface cleaning and modification, polymer and textile treatment, sterilization, pollution control, CO2 lasers, excimer lamps, plasma display panels (flat TV screens). More recent research efforts are devoted to biomedical applications and to plasma actuators for flow control. Sinusoidal feeding voltages at various frequencies as well as pulsed excitation schemes are used. Volume as well as surface barrier discharges can exist in the form of filamentary, regularly patterned or diffuse, laterally homogeneous discharges. The physical effects leading to collective phenomena in volume and surface barrier discharges are discussed in detail. Special attention is paid to self-organization of current filaments and pattern formation. Major similarities of the two types of barrier discharges are elaborated.

  17. Collective phenomena in volume and surface barrier discharges

    Energy Technology Data Exchange (ETDEWEB)

    Kogelschatz, U, E-mail: u.kogelschatz@bluewin.ch [Retired from ABB Corporate Research, Segelhof 1, 5405 Baden (Switzerland)

    2010-11-01

    Barrier discharges are increasingly used as a cost-effective configuration to produce non-equilibrium plasmas at atmospheric pressure. This way, copious amounts of electrons, ions, free radicals and excited species can be generated without significant heating of the background gas. In most applications the barrier is made of dielectric material. Major applications utilizing mainly dielectric barriers include ozone generation, surface cleaning and modification, polymer and textile treatment, sterilization, pollution control, CO{sub 2} lasers, excimer lamps, plasma display panels (flat TV screens). More recent research efforts are devoted to biomedical applications and to plasma actuators for flow control. Sinusoidal feeding voltages at various frequencies as well as pulsed excitation schemes are used. Volume as well as surface barrier discharges can exist in the form of filamentary, regularly patterned or diffuse, laterally homogeneous discharges. The physical effects leading to collective phenomena in volume and surface barrier discharges are discussed in detail. Special attention is paid to self-organization of current filaments and pattern formation. Major similarities of the two types of barrier discharges are elaborated.

  18. Role of secondary emission on discharge dynamics in an atmospheric pressure dielectric barrier discharge

    Energy Technology Data Exchange (ETDEWEB)

    Tay, W. H.; Kausik, S. S.; Yap, S. L.; Wong, C. S., E-mail: cswong@um.edu.my [Plasma Technology Research Centre, Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2014-04-15

    The discharge dynamics in an atmospheric pressure dielectric barrier discharge (DBD) is studied in a DBD reactor consisting of a pair of stainless steel parallel plate electrodes. The DBD discharge has been generated by a 50 Hz ac high voltage power source. The high-speed intensified charge coupled device camera is used to capture the images of filaments occurring in the discharge gap. It is observed that frequent synchronous breakdown of micro discharges occurs across the discharge gap in the case of negative current pulse. The experimental results reveal that secondary emissions from the dielectric surface play a key role in the synchronous breakdown of plasma filaments.

  19. Roles of individual radicals generated by a submerged dielectric barrier discharge plasma reactor during Escherichia coli O157:H7 inactivation

    Directory of Open Access Journals (Sweden)

    Muhammad Saiful Islam Khan

    2015-10-01

    Full Text Available A submerged dielectric barrier discharge plasma reactor (underwater DBD has been used on Escherichia coli O157:H7 (ATCC 35150. Plasma treatment was carried out using clean dry air gas to investigate the individual effects of the radicals produced by underwater DBD on an E. coli O157:H7 suspension (8.0 log CFU/ml. E. coli O157:H7 was reduced by 6.0 log CFU/ml for 2 min of underwater DBD plasma treatment. Optical Emission Spectra (OES shows that OH and NO (α, β radicals, generated by underwater DBD along with ozone gas. E. coli O157:H7 were reduced by 2.3 log CFU/ml for 10 min of underwater DBD plasma treatment with the terephthalic acid (TA OH radical scavenger solution, which is significantly lower (3.7 log CFU/ml than the result obtained without using the OH radical scavenger. A maximum of 1.5 ppm of ozone gas was produced during the discharge of underwater DBD, and the obtained reduction difference in E.coli O157:H7 in presence and in absence of ozone gas was 1.68 log CFU/ml. The remainder of the 0.62 log CFU/ml reduction might be due to the effect of the NO (α, β radicals or due to the combined effect of all the radicals produced by underwater DBD. A small amount of hydrogen peroxide was also generated but does not play any role in E. coli O157:H7 inactivation.

  20. Roles of individual radicals generated by a submerged dielectric barrier discharge plasma reactor during Escherichia coli O157:H7 inactivation

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Muhammad Saiful Islam [Department of Food Biotechnology, University of Science and Technology, Daejeon, 305-350 (Korea, Republic of); Lee, Eun-Jung [Food Safety Research Group, Korea Food Research Institute, Seongnam-si, Gyeonggi-Do (Korea, Republic of); Kim, Yun-Ji, E-mail: yunji@kfri.re.kr [Department of Food Biotechnology, University of Science and Technology, Daejeon, 305-350 (Korea, Republic of); Food Safety Research Group, Korea Food Research Institute, Seongnam-si, Gyeonggi-Do (Korea, Republic of)

    2015-10-15

    A submerged dielectric barrier discharge plasma reactor (underwater DBD) has been used on Escherichia coli O157:H7 (ATCC 35150). Plasma treatment was carried out using clean dry air gas to investigate the individual effects of the radicals produced by underwater DBD on an E. coli O157:H7 suspension (8.0 log CFU/ml). E. coli O157:H7 was reduced by 6.0 log CFU/ml for 2 min of underwater DBD plasma treatment. Optical Emission Spectra (OES) shows that OH and NO (α, β) radicals, generated by underwater DBD along with ozone gas. E. coli O157:H7 were reduced by 2.3 log CFU/ml for 10 min of underwater DBD plasma treatment with the terephthalic acid (TA) OH radical scavenger solution, which is significantly lower (3.7 log CFU/ml) than the result obtained without using the OH radical scavenger. A maximum of 1.5 ppm of ozone gas was produced during the discharge of underwater DBD, and the obtained reduction difference in E.coli O157:H7 in presence and in absence of ozone gas was 1.68 log CFU/ml. The remainder of the 0.62 log CFU/ml reduction might be due to the effect of the NO (α, β) radicals or due to the combined effect of all the radicals produced by underwater DBD. A small amount of hydrogen peroxide was also generated but does not play any role in E. coli O157:H7 inactivation.

  1. Experimental Investigation of “Why an AC Dielectric Barrier Discharge Plasma Actuator is Preferred to DC Corona Wind Actuator in Boundary Layer Flow Control?”

    Directory of Open Access Journals (Sweden)

    Gholam reza Tathiri

    2014-01-01

    Full Text Available In this paper, characteristics of the flow induced in the boundary layer by an AC-Dielectric Barrier Discharge (DBD plasma actuator are compared against those of a DC-corona wind actuator. This is achieved by visualization of the induced flow using smoke injection and measuring the horizontal induced velocity. Our measurements show that the maximum induced velocity of an AC-DBD actuator is about one order of magnitude larger than that of a DC-corona actuator. For an AC-DBD actuator, the induced velocity is maximized on the plate surface while for a DC-corona actuator the induced velocity peaks at about 20mm above the surface. Using flow visualization, we demonstrate that the induced velocity of an AC-DBD actuator is parallel to the surface, while the induced velocity of a DC-corona actuator has components perpendicular to surface.

  2. Period-two discharge characteristics in argon atmospheric dielectric-barrier discharges

    International Nuclear Information System (INIS)

    Period multiplication and chaos behaviors in atmospheric glow discharges are important to understand atmospheric glow plasma stability and to optimize its applications. In this paper, we study the period-two discharge characteristics in argon atmospheric dielectric-barrier discharges using a one-dimension fluid model. Under certain conditions, period-two discharges can occur at different excitation frequencies and exhibit different current and voltage behaviors. When the discharge current becomes highly symmetrical the period-two discharge can reach to a steady state, which sustains over a broad frequency range. At the sufficiently high excitation frequency, the period-two discharge in atmospheric argon shows noticeably different behaviors from the discharges generated at kilohertz frequency. The spatial characteristics of period-two discharge as well as the influence of driving frequency on period-two discharge behaviors are also investigated.

  3. Dielectric-Barrier Discharges. Principle and Applications

    OpenAIRE

    Kogelschatz, U.; Eliasson, B.; Egli, W.

    1997-01-01

    Dielectric-barrier discharges (silent discharges) are non-equilibrium discharges that can be conveniently operated over a wide temperature and pressure range. At about atmospheric pressure electrical breakdown occurs in many independent thin current filaments. These short-lived microdischarges have properties of transient high pressure glow discharges with electron energies ideally suited for exciting or dissociating background gas atoms and molecules. The traditional application for large-sc...

  4. Discharge analysis and electrical modeling for the development of efficient dielectric barrier discharge

    Energy Technology Data Exchange (ETDEWEB)

    Pal, U N; Kumar, M; Tyagi, M S; Meena, B L; Khatun, H; Sharma, A K, E-mail: paludit@gmail.co [Electron Tubes Area, Central Electronics Engineering Research Institute (CEERI)/ Council of Scientific and Industrial Research (CSIR), Pilani, Rajasthan-333031 (India)

    2010-02-01

    Dielectric-barrier discharges (DBDs) are characterized by the presence of at least one insulating layer in contact with the discharge between two planar or cylindrical electrodes connected to an AC/pulse power supply. The dielectric layers covering the electrodes act as current limiters and prevent the transition to an arc discharge. DBDs exist usually in filamentary mode, based on the streamer nature of the discharges. The main advantage of this type of electrical discharges is that nonequilibrium and non-thermal plasma conditions can be established at atmospheric pressure. VUV/UV sources based on DBDs are considered as promising alternatives of conventional mercury-based discharge plasmas, producing highly efficient VUV/UV radiation. The experiments have been performed using two coaxial quartz double barrier DBD tubes, which are filled with Xe/Ar at different pressures. A sinusoidal voltage up to 2.4 kV peak with frequencies from 20 to 100 kHz has been applied to the discharge electrodes for the generation of microdischarges. A stable and uniform discharge is produced in the gas gap between the dielectric barrier electrodes. By comparisons of visual images and electrical waveforms, the filamentary discharges for Ar tube while homogeneous discharge for Xe tube at the same conditions have been confirmed. The electrical modeling has been carried out to understand DBD phenomenon in variation of applied voltage waveforms. The simulated discharge characteristics have been validated by the experimental results.

  5. Development of dielectric-barrier-discharge ionization.

    Science.gov (United States)

    Guo, Cheng'an; Tang, Fei; Chen, Jin; Wang, Xiaohao; Zhang, Sichun; Zhang, Xinrong

    2015-03-01

    Dielectric-barrier-discharge ionization is an ambient-ionization technique. Since its first description in 2007, it has attracted much attention in such fields as biological analysis, food safety, mass-spectrometry imaging, forensic identification, and reaction monitoring for its advantages, e.g., low energy consumption, solvent-free method, and easy miniaturization. In this review a brief introduction to dielectric barrier discharge is provided, and then a detailed introduction to the dielectric-barrier-discharge-ionization technique is given, including instrumentation, applications, and mechanistic studies. Based on the summary of reported work, possible future uses of this type of ionization source are discussed at the end. PMID:25510973

  6. Dielectric barrier discharges revisited: the case for mobile surface charge

    Science.gov (United States)

    Peeters, F. J. J.; Rumphorst, R. F.; van de Sanden, M. C. M.

    2016-06-01

    We propose a mechanism to explain many features of the multi-filament dielectric barrier discharge: while part of the charge deposited during previous discharge cycles is immobile on the dielectric over time periods of seconds, the larger fraction of the deposited charge must be mobile on time-scales of hundreds of ns. For alumina, we estimate that a sheet resistance of 3 MΩ sq‑1 is consistent with the multi-filament discharge; an increase in conductivity of at least 12 orders of magnitude. The existence of this type of plasma-induced surface conductivity could prove relevant in modeling a wide range of plasma devices, in addition to DBD.

  7. Computational study of temporal behavior of incident species impinging on a water surface in dielectric barrier discharge for the understanding of plasma-liquid interface

    Science.gov (United States)

    Suda, Yoshiyuki; Oda, Akinori; Kato, Ryo; Yamashita, Ryuma; Tanoue, Hideto; Takikawa, Hirofumi; Tero, Ryugo

    2015-01-01

    A lipid bilayer is a basic structure of the cell membrane and is stable in liquid solution. In this study, we analyzed dielectric barrier discharge (DBD) containing water on a quartz substrate using a one-dimensional fluid model. To simulate atmospheric pressure plasma for practical use, a tiny amount of N2 gas (0.5 ppm) was added to He gas ambient as an impure gas. The calculated current-voltage (I-V) characteristics reproduced the measured ones qualitatively. We focused on the behavior of DBD at the plasma-liquid interface and analyzed the temporal behavior of the electric field strength and incident fluxes of charged, excited, and radical species on the water surface. By varying the gap length, it was shown that the maximum electric field strength in an AC cycle saturated at gap lengths ≥0.15 cm. The incident fluxes of N2+ and He2+ on the water surface are almost the same and show strong correlations with the electric field in the vicinity of the water surface.

  8. Surface modification of thermoplastic poly(vinyl alcohol)/saponite nanocomposites via surface-initiated atom transfer radical polymerization enhanced by air dielectric discharges barrier plasma treatment

    Energy Technology Data Exchange (ETDEWEB)

    Zhen Weijun [State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute, Sichuan University, Chengdu 610065 (China); Lu Canhui, E-mail: canhuilu@scu.edu.cn [State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute, Sichuan University, Chengdu 610065 (China)

    2012-07-01

    To improve the water resistance of thermoplastic poly(vinyl alcohol)/saponite nanocomposites (TPVA), a simple two-step method was developed for the covalent immobilization of atom transfer radical polymerization (ATRP) initiators on the TPVA surfaces enhanced by air dielectric barrier discharges (DBD) plasma treatment, and hydrophobic poly(methyl methacrylate) (PMMA) brushes were then grafted onto the surface of TPVA via surface-initiated atom transfer radical polymerization (SI-ATRP). The chemical composition, morphology and hydrophobicity of the modified TPVA surfaces were characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), respectively. The water resistance of the surface-functionalized PMMA was evaluated by the contact angle and water adsorption method. It was shown that air DBD plasma treatment activated the TPVA surface and accelerated the immobilization of ATRP initiator on the TPVA surface. Compared with TPVA control, TPVA modified by SI-ATRP can be grafted well-defined and covalently tethered network PMMA brushes onto the surface and the hydrophobicity of TPVA were significantly enhanced.

  9. Comparison of three excitation schemes for cylindrical dielectric barrier discharges

    OpenAIRE

    Brockhaus, A.; Sauerbier, R.; Engemann, J.

    2009-01-01

    Abstract Three dielectric barrier discharge jets have been analyzed mainly by spectroscopic methods. Power densities, electron concentrations, and heavy particle temperatures are in the same range for the jets. All three jets are excited by sinusoidal voltages with kilohertz frequencies. High speed imaging proves that for quite different excitation schemes the jet plasma consists of isolated, fast moving, light-emitting structures. These so-called plasma bul...

  10. Thrust Measurement of Dielectric Barrier Discharge (DBD) Plasma Actuators: New Anti-Thrust Hypothesis, Frequency Sweeps Methodology, Humidity and Enclosure Effects

    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 grounded large-diameter metal sleeve. Strong dependence on humidity is also shown; the thrust significantly increased with decreasing humidity, e

  11. THE STUDY OF THE EFFECTS OF SURFACE DIELECTRIC BARRIER DISCHARGE LOW TEMPERATURE PLASMA PRODUCTS ON SPRING AND WINTER WHEAT GERMINATION

    OpenAIRE

    A.V. Lazukin; I.V. Lyubushkina; K.A. Kirichenko; O.I. Grabelnych; S.A. Krivov; Nikitin, A.M.

    2015-01-01

    The use of ion-plasma technologies for treatment of seeds of different crop plants is particularly important for regions that exist in environment of risk farming. This is due to the lack of supplies in the treatment, durability, reliability and performance of these technologies. However, the mixed results of studies obtained for different species and varieties of seeds, make it necessary to detail compare the effects of the low-temperature plasma products for different cultures. This paper p...

  12. Discharge characteristics of dielectric barrier discharge (DBD) based VUV/UV sources

    Energy Technology Data Exchange (ETDEWEB)

    Pal, U N; Kumar, M; Khatun, H; Sharma, A K [Electron Tubes Area, Central Electronics Engineering Research Institute, Pilani, Rajasthan-333031 (India)], E-mail: paludit@gmail.com

    2008-05-01

    Dielectric-barrier discharges (DBDs) are characterized by the presence of at least one insulating layer in contact with the discharge between two planar or cylindrical electrodes connected to an AC/pulse power supply. The dielectric layers covering the electrodes act as current limiters and prevent the transition to an arc discharge. DBDs exist usually in filamentary mode, based on the streamer nature of the discharges. The main advantage of this type of electrical discharges is that nonequilibrium and non-thermal plasma conditions can be established at atmospheric pressure. VUV/UV sources based on DBDs are considered as promising alternatives of conventional mercury-based discharge plasmas, producing highly efficient VUV/UV radiation. The experiments have been performed using coaxial and planar geometry of DBD (gas gap: 1-3 mm) made of quartz with N{sub 2}/Ar/Xe gas at different pressures. A proper ultra high vacuum system and gas filing system has been made for the processing and characterization of DBD tubes. A RF generator (20-100 kHz, 0-2.4 kV peak) is used for discharges in DBD tube. A stable and uniform discharge is produced in the gas gap between the dielectric barrier electrodes. The discharge characteristics have been analyzed by V-I characteristics and Lissajous figure and found that the spatial discharge processes varies strongly according to the applied voltage waveform, pressure of filled gas and geometry of tube.

  13. The Nonlinear Behaviors in Atmospheric Dielectric Barrier Multi Pulse Discharges

    Science.gov (United States)

    Zhang, Dingzong; Wang, Yanhui; Wang, Dezhen

    2016-08-01

    An in-depth and comprehensive understanding of the complex nonlinear behaviors in atmospheric dielectric barrier discharge is significant for the stable operation and effective control of the plasma. In this paper, we study the nonlinear behaviors in argon atmospheric dielectric barrier multi pulse discharges by a one-dimensional fluid model. Under certain conditions, the multi pulse discharge becomes very sensitive with the increase of frequency, and the multi pulse period-doubling bifurcation, inverse period-doubling bifurcation and chaos appear frequently. The discharge can reach a relatively steady state only when the discharges are symmetrical between positive and negative half cycle. In addition, the effects of the voltage on these nonlinear discharges are also studied. It is found that the amplitude of voltage has no effects on the number of discharge pulses in multi-pulse period-doubling bifurcation sequences; however, to a relatively stable periodic discharge, the discharge pulses are proportional to the amplitude of the applied voltage within a certain range. supported by National Natural Science Foundation of China (No. 11447244), the Science Foundation of Hengyang Normal University of China (No. 14B41), the Construct Program of the Key Discipline in Hunan Province, and the Hunan Provincial Applied Basic Research Base of Optoelectronic Information Technology of China (No. GDXX010)

  14. Sterilization and Mechanism of Microorganisms on A4 Paper by Dielectric Barrier Discharges Plasma at Atmospheric Pressure

    Science.gov (United States)

    Xianghong, Jia; Jun, Wan; Jinhua, Yang; Feng, Xu; Shouguo, Wang

    2009-10-01

    This study investigated the microorganisms' sterilization and mechanism by a DBD plasma device at atmospheric pressure. The device including a transfer system and two roller-electrodes is driven by sine-wave high voltages at frequencies of 15 kHz. Normal A4 papers were used to study the effects of the sterilization on their surfaces by analyzing the number of the living bacteria cells. The state of Escherichia coil's DNA were also measured by agarose gel electrophoresis after sterilization to analyze the inactivation mechanisms. Experimental results indicated that microorganisms on the surface of A4 Papers almost were destroyed while the papers went through the device and there was no any damage of the paper during the process. The main reason engendered bacteria death was due to the double chains of the DNA broken by the plasma.

  15. Development of dielectric barrier discharging power supply

    Science.gov (United States)

    Gao, Yinghui; Liu, Kun; Fu, Rongyao; Sun, Yaohong; Yan, Ping

    2015-11-01

    Due to the demand of a dielectric barrier discharge power supply, a high voltage and high frequency AC power supply was designed and implemented. Its output voltage is standard or approximate standard sine waveform with the frequency range of 1 kHz to 50 kHz. The output voltage and output frequency can be adjusted individually. The maximum output power of the power supply is 2 kW. It can be operated through local or remote control. The power supply has been used in the dielectric barrier discharging research under different conditions.

  16. Plasma Discharge Process in a Pulsed Diaphragm Discharge System

    International Nuclear Information System (INIS)

    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. (low temperature plasma)

  17. INHIBITION OF CANDIDA ALBICANS GROWTH ON SURFACES TREATED BY DIELECTRIC BARRIER DISCHARGE WITH VARIOUS BARRIERS

    OpenAIRE

    Jan Sláma; Vítezslav Kríha

    2014-01-01

    Discharges generating low temperature plasma at atmospheric pressure have the potential to treat surfaces biologically contaminated by organic matter in a non-destructive manner. We have been studying ways of inhibiting the growth of microorganisms with the use of dielectric barrier discharge (DBD) plasma. The effect of the choice of a barrier material and its thickness on thegermicide properties of the DBD is described. We used Saboraud agar inoculated by 105 cfu/cm2 of Candida albicans yeas...

  18. Dielectric barrier discharge source for supersonic beams

    Energy Technology Data Exchange (ETDEWEB)

    Luria, K.; Lavie, N.; Even, U. [Sackler School of Chemistry, Tel Aviv University, Tel Aviv 69978 (Israel)

    2009-10-15

    We present a new excitation source for pulsed supersonic beams. The excitation is based on dielectric barrier discharge in the beam. It produces cold beams of metastable atoms, dissociated neutral atoms from molecular precursors, and both positive and negative ions with high efficiency and reliability.

  19. 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.

  20. STUDY OF DESTRUCTION PROCESSES OF SYNTHETIC SURFACE-ACTIVE SUBSTENCES (SURFFACTANTS IN BARRIER DISCHARGE

    Directory of Open Access Journals (Sweden)

    V.I. Grinevich

    2012-06-01

    Full Text Available Kinetic data of degradation on aqueous solutions of surfactants in the plasma of barrier discharge are presented. The possible mechanism of proceeding processes is offered and considered. It is shown that the treatment in a barrier discharge results in decomposition efficiency of 95%. It is established that the main product of degradation are carboxylic acids.

  1. Dielectric-barrier discharges in two-dimensional lattice potentials

    OpenAIRE

    Sinclair, Josiah; Walhout, Matthew

    2011-01-01

    We use a pin-grid electrode to introduce a corrugated electrical potential into a planar dielectric-barrier discharge (DBD) system, so that the amplitude of the applied electric field has the profile of a two-dimensional square lattice. The lattice potential provides a template for the spatial distribution of plasma filaments in the system and has pronounced effects on the patterns that can form. The positions at which filaments become localized within the lattice unit cell vary with the widt...

  2. Electric field in an AC dielectric barrier discharge overlapped with a nanosecond pulse discharge

    Science.gov (United States)

    Goldberg, Benjamin M.; Shkurenkov, Ivan; Adamovich, Igor V.; Lempert, Walter R.

    2016-08-01

    The effect of ns discharge pulses on the AC barrier discharge in hydrogen in plane-to-plane geometry is studied using time-resolved measurements of the electric field in the plasma. The AC discharge was operated at a pressure of 300 Torr at frequencies of 500 and 1750 Hz, with ns pulses generated when the AC voltage was near zero. The electric field vector is measured by ps four-wave mixing technique, which generates coherent IR signal proportional to the square of electric field. Absolute calibration was done using an electrostatic (sub-breakdown) field applied to the discharge electrodes, when no plasma was generated. The results are compared with one-dimensional kinetic modeling of the AC discharge and the nanosecond pulse discharge, predicting behavior of both individual micro-discharges and their cumulative effect on the electric field distribution in the electrode gap, using stochastic averaging based on the experimental micro-discharge temporal probability distribution during the AC period. Time evolution of the electric field in the AC discharge without ns pulses, controlled by a superposition of random micro-discharges, exhibits a nearly ‘flat top’ distribution with the maximum near breakdown threshold, reproduced quite well by kinetic modeling. Adding ns pulse discharges on top of the AC voltage waveform changes the AC discharge behavior in a dramatic way, inducing transition from random micro-discharges to a more regular, near-1D discharge. In this case, reproducible volumetric AC breakdown is produced at a well-defined moment after each ns pulse discharge. During the reproducible AC breakdown, the electric field in the plasma exhibits a sudden drop, which coincides in time with a well-defined current pulse. This trend is also predicted by the kinetic model. Analysis of kinetic modeling predictions shows that this effect is caused by large-volume ionization and neutralization of surface charges on the dielectrics by ns discharge pulses. The present

  3. Electrical and spectral characteristics of an atmospheric pressure argon plasma jet generated with tube-ring electrodes in surface dielectric barrier discharge

    International Nuclear Information System (INIS)

    An atmospheric-pressure argon plasma jet is generated with tube-ring electrodes in surface dielectric barrier discharge by a sinusoidal excitation voltage at 8 kHz. The electrical and spectral characteristics are estimated such as conduction and displacement current, electric-field, electron temperature, rotational temperature of N2 and OH, electronic excitation temperature, and oxygen atomic density. It is found that the electric-field magnitudes in the top area of the ground electrode are higher than that in the bottom area of the power electrode, and the electron temperature along radial direction is in the range of 9.6–10.4 eV and along axial direction in the range of 4.9–10 eV. The rotational temperature of N2 obtained by comparing the simulated spectrum with the measured spectrum at the C3Πu → B3Πg(Δv = − 2) band transition is in the range of 342–387 K, the electronic excitation temperature determined by Boltzmann's plot method is in the range of 3188–3295 K, and the oxygen atomic density estimated by the spectral intensity ratio of atomic oxygen line λ = 844.6 nm to argon line λ = 750.4 nm is in the order of magnitude of 1016 cm−3, respectively. - Highlights: ► The conduction and displacement current are calculated by equivalent circuit diagram. ► The 2D distribution of electric-field magnitude is calculated by ElecNet software. ► The electron temperature along axial direction is in the range of 4.9–10 eV. ► The oxygen atomic density is about a magnitude of 1016 cm−3

  4. Complex dynamic behaviors of nonequilibrium atmospheric dielectric-barrier discharges

    International Nuclear Information System (INIS)

    In this paper, a one-dimensional fluid model is used to investigate complex dynamic behaviors of a nonequilibrium dielectric-barrier discharge (DBD) in atmospheric helium. By projecting its evolution trajectory in the three-dimensional phase space of gas voltage, discharge current density, and electrode-surface charge density, the atmospheric DBD is shown to undergo a sequence of complex bifurcation processes when the applied voltage is increased from prebreakdown to many times of the breakdown voltage. Once the gas voltage exceeds the breakdown voltage, the discharge plasma is found to acquire negative differential conductivity and as a result its stability is compromised. For atmospheric DBD, however, the resulting low plasma stability is mitigated by a rapid accumulation of surface charges on the electrodes, thus allowing the atmospheric DBD to retain their character as a glow discharge. At certain values of the applied voltage, a highly complex phenomenon of period multiplication is observed in which the period of the discharge current is three times that of the applied voltage. This suggests that nonequilibrium atmospheric DBD may support evolution patterns that are quasiperiodic or even chaotic. These complex dynamic behaviors are likely to be critical to a full understanding of plasma stability of nonequilibrium atmospheric discharges and to the development of their instability control strategies

  5. Particle simulation of filamentary formation in dielectric barrier discharge.

    Science.gov (United States)

    Fan, Weili; Dong, Lifang

    2015-11-01

    Dielectric barrier discharge (DBD) is well known for its extensive industrial applications. Recently, new attention has been paid to DBD as a system of rich nonlinear dynamics to study the self-organized filamentary patterns. Though a number of experimental studies have been implemented, the involved physics is still not completely clear, partially due to the limitation of the available space and time-resolved diagnostics. Computer simulation has proven to be an effective tool to give insights into the discharge mechanism. So far, most simulations presented are based on fluid models. However, since the plasma is non-equilibrium in DBD where the particle velocities may deviate from the Maxwellian distribution, self-consistent kinetic simulations are required. In this paper, two successive filamentary discharges in DBD have been studied by use of two-dimensional particle-in-cell simulation with Monte Carlo collisions included (PIC-MCC). The formation of multiple filaments and the involved electric fields, electric potentials, plasma densities, and particle temperatures are presented. Results show that both of the surface charges and space charges play significant roles in the discharges. The total electric field in the gas gap has been completely reversed before the ac voltage hit zero, due to the accumulation of the surface charges, which triggers the next discharge. The space charges always exist between two successive discharges, which provides the `seed charges' for reignition of the filaments. This modeling has revealed significant details of the discharge behaviors, which greatly improved our understanding of DBD mechanisms.

  6. Low-temperature hydrogenation of diamond nanoparticles using diffuse coplanar surface barrier discharge at atmospheric pressure

    Czech Academy of Sciences Publication Activity Database

    Kromka, Alexander; Čech, J.; Kozak, Halyna; Artemenko, Anna; Ižák, Tibor; Čermák, Jan; Rezek, Bohuslav; Černák, M.

    2015-01-01

    Roč. 252, č. 11 (2015), s. 2602-2607. ISSN 0370-1972 R&D Projects: GA ČR(CZ) GBP108/12/G108 Institutional support: RVO:68378271 Keywords : atmospheric plasma * diamond nanoparticles * diffuse coplanar surface barrier discharge * FTIR * XPS Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.489, year: 2014

  7. Dielectric barrier discharge in a two-phase mixture

    International Nuclear Information System (INIS)

    This paper reports the experimental investigation of the dielectric barrier discharge in which the gap area is filled with a two-phase mixture (TPM), air and solid particles. We found that there are two kinds of discharges in the TPM. One is the surface discharge generated on the surface of the solid particles and the other is the filament discharge generated in the air void. For the case of low volume fraction of solid particles, the surface discharge starts to occur when the applied voltage is higher than the onset voltage. At a further voltage increase, the filament discharge takes place at the same time. For the case of high volume fraction, such as the packed-bed reactor, only the surface discharge exists. Under the condition of the same volume fraction, the larger the diameter of the solid particles, the lower the surface discharge onset voltage. As a conclusion, we think that the plasma reactor using the form of low volume fraction of solid particles may be a better choice for waste-gas treatment enhanced by catalysts

  8. FLUIDS, PLASMAS AND ELECTRIC DISCHARGES: The influence of the structures and compounds of DLC coatings on the barrier properties of PET bottles

    Science.gov (United States)

    Yang, Li; Wang, Zhen-Duo; Zhang, Shou-Ye; Yang, Li-Zhen; Chen, Qiang

    2009-12-01

    To reduce the oxygen transmission rate through a polyethylene terephthalate (PET) bottle (an organic plastic) diamond-like carbon (DLC) coatings on the inner surface of the PET bottle were deposited by radio frequency plasma-enhanced chemical vapour deposition (RF-PECVD) technology with C2H2 as the source of carbon and Ar as the diluted gas. As the barrier layer to humidity and gas permeation, this paper analyses the DLC film structure, composition, morphology and barrier properties by Fourier transform infrared, atomic force microscopy, scanning electron microscopy and oxygen transmission rate in detail. From the spectrum, it is found that the DLC film mainly consists of sp3 bonds. The barrier property of the films is significantly relevant to the sp3 bond concentration in the coating, the film thickness and morphology. Additionally, it is found that DLC film deposited in an inductively coupled plasma enhanced capacitively coupled plasma source shows a compact, homogeneous and crack-free surface, which is beneficial for a good gas barrier property in PET bottles.

  9. Modelling of the homogeneous barrier discharge in helium at atmospheric pressure

    International Nuclear Information System (INIS)

    Numerical calculations of spatio-temporal characteristics of the homogeneous barrier discharge in helium are performed by means of a one-dimensional fluid model. The influence of the elementary processes on the discharge behaviour is studied by variation of the corresponding rate constants. The simulation and the analytical interpretation are carried out for two basic modes of the homogeneous barrier discharge, i.e. the Townsend and glow modes. The Townsend discharge is characterized by the absence of quasineutral plasma; several current peaks may occur during the half-cycle. The oscillations of the current are caused by a lag between the ion production nearby the anode and the subsequent ion-electron emission on the cathode. The specificity of the glow discharge is the development of a cathode region and a positive column during the breakdown, as well as the presence of quasineutral plasma in subsequent phases. The positive column occurs because the shielding of the external field by the plasma is not instantaneous. The dependence of the discharge behaviour on the external parameters, such as the amplitude and frequency of the applied voltage, discharge gap width, and thickness of dielectric barriers, is analysed. The mode of the discharge is governed mostly by the gap width and barrier thickness and depends weakly on the amplitude and frequency of the applied voltage. As the barriers are thin and the discharge gap is sufficiently wide, the glow mode occurs; otherwise, the discharge is Townsend

  10. Experimental determination of dielectric barrier discharge capacitance.

    Science.gov (United States)

    Pipa, A V; Hoder, T; Koskulics, J; Schmidt, M; Brandenburg, R

    2012-07-01

    The determination of electrical parameters (such as instantaneous power, transferred charge, and gas gap voltage) in dielectric barrier discharge (DBD) reactors relies on estimates of key capacitance values. In the classic large-scale sinusoidal-voltage driven DBD, also known as silent or ozonizer discharge, capacitance values can be determined from charge-voltage (Q-V) plot, also called Lissajous figure. For miniature laboratory reactors driven by fast pulsed voltage waveforms with sub-microsecond rise time, the capacitance of the dielectric barriers cannot be evaluated from a single Q-V plot because of the limited applicability of the classical theory. Theoretical determination can be problematic due to electrode edge effects, especially in the case of asymmetrical electrodes. The lack of reliable capacitance estimates leads to a "capacitance bottleneck" that obstructs the determination of other DBD electrical parameters in fast-pulsed reactors. It is suggested to obtain capacitance of dielectric barriers from a plot of the maximal charge versus maximal voltage amplitude (Q(max) - V(max) plot) in a manner analogous to the classical approach. The method is examined using measurements of current and voltage waveforms of a coaxial DBD reactor in argon at 100 mbar driven by square voltage pulses with a rise time of 20 ns and with different voltage amplitudes up to 10 kV. Additionally, the applicability of the method has been shown for the data reported in literature measured at 1 bar of nitrogen-oxygen gas mixtures and xenon. PMID:22852728

  11. The micro-discharge family (dark, corona, and glow-discharge) for analytical applications realized by dielectric barriers.

    Science.gov (United States)

    Franzke, J

    2009-10-01

    The similarity principles of electric plasmas, and the current-voltage characteristics of the most prominent kinds of discharges used for analytical applications, are discussed. Most of the discharges can be miniaturized, and some of the analytical applications of different discharges can be realized by use of dielectric barriers for analytical applications, for example element spectrometry, as an ionization source for ion-mobility spectrometry or organic mass spectrometry, and as an electrospray ionization source. PMID:19434400

  12. Dielectric-barrier discharges in two-dimensional lattice potentials

    CERN Document Server

    Sinclair, Josiah

    2011-01-01

    We use a pin-grid electrode to introduce a corrugated electrical potential into a planar dielectric-barrier discharge (DBD) system, so that the amplitude of the applied electric field has the profile of a two-dimensional square lattice. The lattice potential provides a template for the spatial distribution of plasma filaments in the system and has pronounced effects on the patterns that can form. The positions at which filaments become localized within the lattice unit cell vary with the width of the discharge gap. The patterns that appear when filaments either overfill or under-fill the lattice are reminiscent of those observed in other physical systems involving 2d lattices. We suggest that the connection between lattice-driven DBDs and other areas of physics may benefit from the further development of models that treat plasma filaments as interacting particles.

  13. 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

  14. Self-Consistent Model for Atmospheric Pressure Dielectric Barrier Discharges in Helium

    International Nuclear Information System (INIS)

    We show the necessity of leaving out the approximation of constant average electron energy in many fluid models. For this purpose a one-dimensional self-consistent model for He atmospheric barrier discharges is developed. With this model, the electron energy distribution function in the atmospheric pressure glow discharge is obtained without introducing much difficulty, and the new model is readily implemented for investigating discharges in complicated gases. (gases, plasmas, and electric discharges)

  15. Pulsed corona and dielectric-barrier discharge processing of trichloroethylene

    Energy Technology Data Exchange (ETDEWEB)

    Hsiao, M.C.; Merritt, B.T.; Penetrante, B.M.; Vogtlin, G.E.; Wallman, P.H. [Lawrence Livermore National Lab., CA (United States)

    1995-12-31

    This paper presents experimental results on the plasma assisted decomposition of dilute concentrations (100--200 ppm) of trichloroethylene (TCE) in atmospheric-pressure dry air streams by pulsed corona and dielectric-barrier discharge processing. The experiments were performed at gas temperatures up to 300 A1C. One of the objectives in these experiments is to study the effect of gas temperature on the removal chemistry and product formation. The data on the gas temperature dependence provide a good basis for elucidating the chemical kinetics of TCE decomposition in the plasma. Under identical gas conditions the type of electrical discharge reactor does not affect the electrical energy requirements for decomposing the same amount of TCE; the reactor type also does not affect the product formation. For input energy densities up to 300 Joules per liter, the authors observe that carbon monoxide (CO) and carbon dioxide (CO2) are only minor products in the decomposition of TCE. The main organic products are phosgene and dichloroacetyl chloride (DCAC), as inferred from the Fourier Transform Infrared (FTIR) spectra. Processing at higher gas temperatures (around 300 A1C) increases the electrical energy required to remove the same amount of TCE; however, the CO and CO2 yields increase substantially and higher amounts of hydrochloric acid (HCl) are formed. These trends suggest increased competition from decomposition of DCAC and/or phosgene at high temperatures. In all cases, pulsed corona or dielectric-barrier discharge processing produces CO preferentially over CO2.

  16. Characteristics of pulsed discharge plasma in water

    OpenAIRE

    Namihira, Takao; Yamaguchi, Takahiro; Yamamoto, Kunihiro; Jaegu, Choi; Kiyan, Tsuyoshi; Sakugawa, Takashi; Katsuki, Sunao; Akiyama, Hidenori; ナミヒラ, タカオ; ヤマグチ, タカヒロ; ヤマモト, クニヒロ; ジェグ, チョイ; キヤン, ツヨシ; サクガワ, タカシ; カツキ, スナオ

    2005-01-01

    Recently, pulsed discharge plasma produced underwater has been an attractive method to treat wasted water. It is well known that pulsed discharge in water has some physical effects, such as an intense electric field at a tip of discharge plasma, an ultra violet radiation, a chemically radical formation and shockwave generation, for cleaning water. However, the physical characteristics of the pulsed discharge plasma induced underwater are still unclear. For the optimization of the water treatm...

  17. Study of surface dielectric barrier discharge generated using liquid electrodes in different gases

    International Nuclear Information System (INIS)

    Surface dielectric barrier discharges with conductive water-solution electrodes were generated at atmospheric pressure air, nitrogen, oxygen, and argon. The discharges were studied by conventional and high-speed camera photography. Plasma rotational and vibrational temperatures and the electron number density were estimated using optical emission spectroscopy. Surprisingly, especially for oxygen, the discharge was found to generate visually diffuse strongly non-isothermal plasma. This observation indicates the interesting application potential of the discharge for surface plasma treatments of, i.e. the inner and outer surfaces of hollow dielectric bodies. (paper)

  18. Study of surface dielectric barrier discharge generated using liquid electrodes in different gases

    Science.gov (United States)

    Galmiz, O.; Pavlinak, D.; Zemanek, M.; Brablec, A.; Cernak, M.

    2016-02-01

    Surface dielectric barrier discharges with conductive water-solution electrodes were generated at atmospheric pressure air, nitrogen, oxygen, and argon. The discharges were studied by conventional and high-speed camera photography. Plasma rotational and vibrational temperatures and the electron number density were estimated using optical emission spectroscopy. Surprisingly, especially for oxygen, the discharge was found to generate visually diffuse strongly non-isothermal plasma. This observation indicates the interesting application potential of the discharge for surface plasma treatments of, i.e. the inner and outer surfaces of hollow dielectric bodies.

  19. Structure formation in a DC-driven "barrier" discharge:

    NARCIS (Netherlands)

    Ebert, U.; Rafatov, I.; Sijacic, D.; Schmidt, J.; Simek, M.; Pekarek, S.; Prukner, V.

    2007-01-01

    A DC-driven "barrier" discharge is a gas discharge layer and a high-Ohmic semiconductor layer sandwiched between planar electrodes to which a DC voltage is applied. The system resembles a dielectric barrier discharge, but is even simpler, as the external boundary conditions allow for a completely ho

  20. CO2 valorization by means of Dielectric Barrier Discharge

    International Nuclear Information System (INIS)

    As atmospheric pollution is causing several environmental problems it is incumbent to reduce the impact of pollution on the environment. One particular problem is the production of CO2 by many transport and industrial applications. Instead of stocking CO2 and instead of being a product, it can be used as a source. The case considered is the CO2 reformation of methane producing hydrogen and CO. It is an endothermic reaction, for which the activation barrier needs to be surpassed. This can be done efficiently by the method of Dielectric Barrier Discharge. The process relies on the collision of electrons, which are accelerated under an electrical field that is created in the discharge area. This leads to the formation of reactive species, which facilitate the abovementioned reaction. This study is performed using a Matlab program with the Reaction Engineering module in COMSOL (with an incorporated kinetic mechanism) in order to model the discharge phase. Then COMSOL (continuity and Navier-Stokes equations) is used to model the flow in the post-discharge phase. The results showed that both a 2D and 3D model can be used to model the chemical-plasma process. These methods need strongly reduced kinetic mechanism, which in some cases can cause loss of precision.

  1. Dielectric barrier discharge in air with a controllable spatial distribution—a tomographic investigation

    Science.gov (United States)

    van der Schans, M.; Sobota, A.; Kroesen, G. M. W.

    2016-05-01

    A novel dielectric barrier discharge source with a controllable discharge distribution has been designed for operation in atmospheric air. A predictable distribution has been achieved through the design of the powered electrode and the dielectric barrier. Optical emission tomography is used to study the discharge distribution. The method and its applicability in studies of non-symmetric plasmas are discussed in the paper. The results show that a desired discharge distribution may be achieved through the manipulation of the electric field amplification by the powered electrode and it is found that the discharge shape resembles the field imposed at the powered electrode only. Together with the flexibility of the plasma source design, this can prove highly advantageous for the treatment of irregularly shaped surfaces in plasma medicine and plasma surface processing at atmospheric pressure.

  2. Catalytic Decomposition of Toluene Using Various Dielectric Barrier Discharge Reactors

    Institute of Scientific and Technical Information of China (English)

    YE Daiqi; HUANG Haibao; CHEN Weili; ZENG Ronghui

    2008-01-01

    Decomposition of toluene was experimentally investigated with various dielectric barrier discharge (DBD) reactors, such as wire-cylinder, wire-plate and plate-to-plate, combined with multi-metal oxides catalyst (Mn-Ni-Co-Cu-Ox/Al2O3) loaded on the cordierite honeycomb and nickel foam, respectively. The effects of some factors including the residence time, reactor configuration and catalyst, upon the toluene destruction were studied. Results revealed that the use of in-plasma catalysis was more helpful to enhancing the DRE (destruction and removal efficiency) and reducing the O3 formation than that of either post-plasma catalysis or plasma alone. It was demonstrated that the wire-plate reactor was favorable for the oxidation reaction of toluene and the nickel foam-supported catalysts exhibited good activity.

  3. SO2 removal from air with dielectric barrier discharges

    International Nuclear Information System (INIS)

    Dielectric barrier discharges are sources of non-thermal plasmas, in which chemical active particles are generated effectively. One of the most promising applications is chemical processing of gaseous substances, e.g. synthesis or decomposition. The removal of air pollutants such as sulfur dioxide from dry and humid air at atmospheric pressure is investigated experimentally as well as theoretically. The role of chemically active particles, especially of atomic oxygen and of OH radicals, is shown. Optimal conditions of the removal process are determined

  4. Efficiency of ozone production by dielectric coplanar surface barrier discharge in synthetic air

    Czech Academy of Sciences Publication Activity Database

    Šimek, Milan; Homola, T.

    Prague, 2007 - (Schmidt, J.; Šimek, M.; Pekárek, S.; Prukner, V.). s. 112 ISBN 978-80-87026-00-7. [International Conference on Phenomena in Ionized Gases/28./. 15.07.2007-20.07.2007, Prague] Institutional research plan: CEZ:AV0Z20430508 Keywords : Ozone * Dielectric * Coplanar * Surface * Barrier * Discharge Subject RIV: BL - Plasma and Gas Discharge Physics

  5. Note: On the use of Rogowski coils as current probes for atmospheric pressure dielectric barrier discharges.

    Science.gov (United States)

    Biganzoli, I; Barni, R; Riccardi, C

    2013-01-01

    A wide bandwidth current probe based on a Rogowski coil was proposed to work down to the nanosecond time scale. It was then used to record the discharge current pulses that characterize the streamer regime of the plasma in a dielectric barrier discharge device. Indeed such plasmas are often made up of intermittent and highly localized structures such as streamers or microdischarges. Characteristics and performances of the probes are discussed together with a few results concerning their application to investigate dielectric barrier discharges and the temporal structure of different pulses of the electrical current. PMID:23387707

  6. Plasma beam discharge in carbon dioxide

    International Nuclear Information System (INIS)

    The paper deals with the dissociation of carbon dioxide in nonequilibrium plasma of a stationary plasma-beam discharge. Experimental results of spectroscopic and probe measurements of plasma parameters are given. Moreover, a mass-spectrometric analysis of gaseous products of the chemical reactions is presented. In addition the measurement of the deposition rate of solid products by means of a quartz oscillator is described. The results show that plasma beam discharge is an effective tool for inducing plasma-chemical reactions. (author)

  7. Atmospheric pressure dielectric barrier discharges for sterilization and surface treatment

    International Nuclear Information System (INIS)

    Atmospheric pressure non-thermal dielectric barrier discharges can be generated in different configurations for different applications. For sterilization, a parallel-plate electrode configuration with glass dielectric that discharges in air was used. Gram-negative bacteria (Escherichia coli and Salmonella enteritidis) and Gram-positive bacteria (Bacillus cereus) were successfully inactivated using sinusoidal high voltage of ∼15 kVp-p at 8.5 kHz. In the surface treatment, a hemisphere and disc electrode arrangement that allowed a plasma jet to be extruded under controlled nitrogen gas flow (at 9.2 kHz, 20 kVp-p) was applied to enhance the wettability of PET (Mylar) film

  8. Atmospheric pressure dielectric barrier discharges for sterilization and surface treatment

    Energy Technology Data Exchange (ETDEWEB)

    Chin, O. H.; Lai, C. K.; Choo, C. Y.; Wong, C. S.; Nor, R. M. [Plasma Technology Research Centre, Physics Department, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Thong, K. L. [Microbiology Division, Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2015-04-24

    Atmospheric pressure non-thermal dielectric barrier discharges can be generated in different configurations for different applications. For sterilization, a parallel-plate electrode configuration with glass dielectric that discharges in air was used. Gram-negative bacteria (Escherichia coli and Salmonella enteritidis) and Gram-positive bacteria (Bacillus cereus) were successfully inactivated using sinusoidal high voltage of ∼15 kVp-p at 8.5 kHz. In the surface treatment, a hemisphere and disc electrode arrangement that allowed a plasma jet to be extruded under controlled nitrogen gas flow (at 9.2 kHz, 20 kVp-p) was applied to enhance the wettability of PET (Mylar) film.

  9. High tension generator for corona barrier discharge

    International Nuclear Information System (INIS)

    Different types of high-voltage generators are in use for the study of low pressure (or atmospheric) discharges. Mostly used are the Tesla coils generators or the power generators working in linear or switching regime. The Tesla coils generators have the advantage of a simple bloc diagram. In exchange, they have a number of short-comings, such as: the difficulty in modifying the frequency of the high voltage pulses, generation of a high voltage and frequency pulse train, the amplitude is not constant.This paper presents a high-voltage generator meant to be used in the study of the dielectric barrier discharges (DBD). The bloc diagram is presented. Performances obtained are as follows: - Generated frequency: 10 Hz - 100 Hz, 100 Hz - 1 KHz, 1 KHz - 10 KHz; - High voltage pulses control: a single pulse from an internal or external generator; - Synchronization with the oscilloscope, variable delay: 5 μs - 0.1 s; - Output voltage: variable both smoothly and in steps: 1 kV -15 kV; - High voltage polarity: mono and bipolar; - Output power during the continuous duty: 300 VA (maximum 600 VA for a short time); - Pulse energy: 0.23 J; - Pulse duration: 4 μs - 50 μs

  10. Stability Modeling of DIII-D Discharges with Transport Barriers

    Science.gov (United States)

    Lao, L. L.; Ferron, J. R.; Lin-Liu, Y. R.; Strait, E. J.; Turnbull, A. D.; Taylor, T. S.; Murakami, M.

    1999-11-01

    The stability of DIII--D discharges with transport barriers is systematically studied by modeling the pressure profiles using a hyperbolic tangent representation with various radii, widths, and amplitudes. The q profiles are modeled using a spline representation with varying q(0), q_min, and ρ_q_min. The equilibria are computed using the EFIT and the TOQ codes based on the parameters from a strongly shaped high triangurality DIII--D long pulse high performance discharge. Stability against the ideal low n=1 and 2 modes is evaluated using the GATO code with a conducting wall at 1.5 a. The results show that the stability improves with increasing transport barrier width and radius but varies weakly with q(0). When the transport barriers are L--mode like and have narrow widths in the plasma core, the stability is limited by the n=1 mode. When they are H--mode like and have large widths extending toward the edge, the stability is limited by the n=2 mode.

  11. Efficiency of ozone production by dielectric coplanar surface barrier discharge in synthetic air

    Czech Academy of Sciences Publication Activity Database

    Šimek, Milan; Homola, T.

    Praha : Institute of Plasma Physics AS CR,v.v..i, 2007 - (Schmidt, J.; Šimek, M.; Pekárek, S.; Prukner, V.), s. 934-938 - (ICPIG). [International Conference on Phenomena in Ionized Gases/28./. Prague (CZ), 15.07.2007-20.07.2007] Institutional research plan: CEZ:AV0Z20430508 Keywords : Ozone * Dielectric * Coplanar * Surface * Barrier * Discharge Subject RIV: BL - Plasma and Gas Discharge Physics

  12. Effects of high-speed airflows on a surface dielectric barrier discharge

    Energy Technology Data Exchange (ETDEWEB)

    Pavon, S [Ecole Polytechnique Federale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, CH-1015 Lausanne (Switzerland); Dorier, J-L [Ecole Polytechnique Federale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, CH-1015 Lausanne (Switzerland); Hollenstein, Ch [Ecole Polytechnique Federale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, CH-1015 Lausanne (Switzerland); Ott, P [Ecole Polytechnique Federale de Lausanne (EPFL), Institut des Sciences de l' Energie, CH-1015 Lausanne (Switzerland); Leyland, P [Ecole Polytechnique Federale de Lausanne (EPFL), Institut des Sciences de l' Energie, CH-1015 Lausanne (Switzerland)

    2007-03-21

    A detailed study of the interaction between high-speed gas flows and surface dielectric barrier discharges (DBD) is presented. In the present paper, it is demonstrated that a DBD can be sustained in transonic airflows, up to isentropic Mach numbers of 1.1. The plasma is characterized electrically, as well as optically with a CCD camera and a photomultiplier tube. Different airflow velocities, plasma excitation frequencies and voltages are investigated. The airflow has a significant influence on the plasma characteristics: the glow component is reduced, the discharge becomes more filamentary and most importantly, the light emission duration from individual microdischarges is reduced by more than a factor of ten at high flow velocities. Large edge effects play a key role in the interaction between the flow and the plasma. These results offer new perspectives for the use of dielectric barrier discharges in transonic and supersonic gas flows and their applications to airflow control and to plasma-assisted combustion.

  13. The different types of dielectric barrier discharge in gas mixtures

    International Nuclear Information System (INIS)

    In this paper results of electrical and optical diagnostics of dielectric barrier discharges operating in different gas mixtures are presented. Discharges burning in pure nitrogen, in mixtures of nitrogen and argon, nitrogen and carbon dioxide, nitrogen and 1.3-butadiene, argon and 1.3-butadiene, argon and carbon dioxide were studied. The investigations were focused on the influence of different admixtures and on the finding of the conditions for the generation of diffuse dielectric barrier discharges (Authors)

  14. 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...

  15. Design and optimization of dielectric barrier discharge microplasma stamps

    Energy Technology Data Exchange (ETDEWEB)

    Lucas, N; Buettgenbach, S [Institut fuer Mikrotechnik, Technische Universitaet Braunschweig, Alte Salzdahlumer Str. 203, D-38124 Braunschweig (Germany); Hinze, A; Klages, C-P [Institut fuer Oberflaechentechnik, Technische Universitaet Braunschweig, Bienroder Weg 53, D-38108 Braunschweig (Germany)], E-mail: n.lucas@tu-bs.de

    2008-10-07

    Microplasma stamps based upon the principle of dielectric barrier discharges are applied to a new type of area-selective surface modification process at atmospheric pressure. This process integrates the surface treatment and lateral microstructuring within one process step. For this purpose the plasma is ignited in cavities which are formed temporarily by compressing the microplasma stamp and the substrate to be treated. In this work we compare different microplasma stamp designs with the objective of minimizing the ignition voltage to the smallest possible value. Several experiments with regard to the ignition voltage have been conducted, operating in air at atmospheric pressure with medium frequency excitation (33 kHz). They contrast the influence of different types of electrical contacts as well as different electrode types and cavity sizes (diameter 100-500 {mu}m) on the ignition voltage. Furthermore the influence of different substrates to be treated and the compression force have been analysed.

  16. Hydrogen Production from Partial Oxidation of Methane by Dielectric Barrier Discharge Plasma Reforming%介质阻挡放电等离子体甲烷部分氧化重整制氢

    Institute of Scientific and Technical Information of China (English)

    王皓; 宋凌珺; 李兴虎; 岳丽蒙

    2015-01-01

    在自制的介质阻挡放电等离子体重整制氢装置上进行了甲烷部分氧化重整制氢的实验研究.本文研究了氧碳(O/C)摩尔比,进气流量,放电间隙,放电区间长度,填充物的直径、形状和材料,放电电压和放电频率对甲烷转化率、氢产率和产物的选择性(H2、CO和CO2)的影响.实验结果表明:放电区域的参数对甲烷转化率有较大的影响.甲烷转化率随着放电区域长度的增大而增大,当放电区域长度从5 cm增大到20 cm时,甲烷转化率从6.87%增大到22.26%,增大率为224%.同时,放电区域的填充物对产氢效果有较大的影响.当反应器填充颗粒时,甲烷转化率比无填充物时高.选择适当介电常数的填充物具有巨大的实际工程意义.另外,氢产率和氢气的选择性随着放电频率的增大而增大,当放电频率从1.5 kHz增大到7.0 kHz时,氢产率从1.10%增大到9.49%,氢气的选择性从21.18%增大到30.06%.实验结果将对碳氢燃料等离子体重整制氢的车载应用提供实验依据.%This paper presents an in-house-designed dielectric barrier discharge (DBD) plasma reformer for hydrogen production via partial oxidation reforming of methane. We examined the effects of oxygen/carbon (O/C) molar ratio, feed flow rate, discharge gap, discharge zone length, fil er diameter, fil er shape, fil er materials, discharge voltage, and discharge frequency on the hydrogen production performance i.e., CH4 conversion rate, H2 yield, and selectivity of products (H2, CO, and CO2). The experimental results showed that the parameters of the discharge zone played an important role in the CH4 conversion rate. For instance, CH4 conversion rate increased with increasing discharge zone lengths. When the discharge zone length increased from 5 to 20 cm, CH4 conversion rate increased from 6.87%to 22.26%, which corresponds to an improvement of 224%. Also, the fil ers in the discharge zone strongly

  17. Biotechnological Applications of Sulfatron Plasma Discharge

    Czech Academy of Sciences Publication Activity Database

    Straňák, V.; Tichý, M.; Kříha, V.; Schöltz, V.; Houser, V.; Špatenka, P.; Šerá, Božena

    Praha : MATFYZPRESS, 2006 - (Šafránková, J.; Pavlů, J.), s. 139-144 ISBN 80-86732-85-1. [Physics of Plasmas and lonized Media. Praha (CZ), 06.06.2006-09.06.2006] Institutional research plan: CEZ:AV0Z60870520 Keywords : plasma * applicationas, * sterilisation * activation * seed germination Subject RIV: BL - Plasma and Gas Discharge Physics

  18. [Determination of electron density in atmospheric pressure radio frequency dielectric barrier discharges by Stark broadening].

    Science.gov (United States)

    Li, Sen; Liu, Zhong-wei; Chen, Qiang; Liu, Fu-ping; Wang, Zheng-duo; Yang, Li-zhen

    2012-01-01

    The use of high frequency power to generate plasma at atmospheric pressure is a relatively new development. An apparatus of atmospheric pressure radio frequency dielectric barrier discharge was constructed. Plasma emission based measurement of electron density in discharge columns from Stark broadening Ar is discribed. The spacial profile of electron density was studied. In the middle of the discharge column, as the input power increases from 138 to 248 W, the electron density rises from 4.038 x 10(21) m(-3) to 4.75 x 10(21) m(-3). PMID:22497121

  19. Sterilization of E.coli bacterium with an atmospheric pressure surface barrier discharge

    Institute of Scientific and Technical Information of China (English)

    Xu Lei; Zhang Rui; Liu Peng; Ding Li-Li; Zhan Ru-Juan

    2004-01-01

    The atmospheric pressure surface barrier discharge (APSBD) in air has been used in killing Escherichia coli (E.coli). There is almost no bacterial colony in the sample after treatment by discharge plasma for 2 min. A diagnostic technique based on mass spectrum has been applied to the discharge gas and the mechanism of killing is discussed.Ozone and monatomic oxide are considered to be the major antimicrobial active species. There is almost no harmful by-product. The experiment proves that APSBD plasma is a very simple, effective and innocuous tool for sterilization.

  20. Carbon dioxide conversion by means of coplanar dielectric barrier discharges

    Science.gov (United States)

    Schiorlin, Milko; Klink, Rouven; Brandenburg, Ronny

    2016-08-01

    To face the worldwide problem of anthropogenic carbon dioxide (CO2) emission new techniques have to be developed. One approach for carbon capture utilization (CCU) is the conversion of CO2 to more valuable chemicals, e.g., carbon monoxide (CO) by means of non-thermal plasma generated at ambient conditions and supplied by excess energy from renewable sources. This paper reports about the effect of the admixture of inert gases, namely nitrogen or argon to CO2 in a coplanar dielectric barrier discharge (DBD). Systematic experiments were conducted to investigate the effects of applied voltage, frequency, flowrate and CO2 concentration in the influent. The composition of products, energy efficiency and yield were determined. Within the investigated parameter ranges, the maximum conversion of CO2 to CO efficiency of 1% was achieved when the specific input energy was 190 J L-1, whereas the maximum CO yield of 0.7% was achieved when the specific input energy was 210 J L-1. In conclusion, the energy efficiency can be significantly increased by operating the plasma in a diluted CO2 gas. Contribution to the topical issue "6th Central European Symposium on Plasma Chemistry (CESPC-6)", edited by Nicolas Gherardi, Ester Marotta and Cristina Paradisi

  1. Decomposing Nitrous Oxide Thruster using Dielectric Barrier Discharge Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The University of Maryland is proposing to use a dielectric barrier discharge (DBD) as a means to dissociate N2O. DBD uses alternating high voltage differences...

  2. Application of dielectric surface barrier discharge for food storage

    OpenAIRE

    Yassine BELLEBNA; Rabah OUIDDIR; Said NEMMICH; Amar TILMATINE

    2015-01-01

    Ozone (O3) is a powerful oxidizer and has much higher disinfection potential than chlorine and other disinfectants. Ozone finds its application mainly in water treatment and air purification Dielectric barrier discharge (DBD) method has proved to be the best method to produce ozone. Dried air or oxygen is forced to pass through a 1-2 mm gap. The aim of this study was to show that disinfection system using ozone generated by dielectric barrier discharge (DBD) is an effective ...

  3. Comparison of the Ac barrier corona with DC positive and negative coronas and barrier discharge

    International Nuclear Information System (INIS)

    Results are presented from experimental studies of ac corona discharges between a point electrode and a dielectric-coated plate in nitrogen, argon, helium, and air in the voltage frequency range f = 50 Hz-50 kHz. The characteristic features of this type of discharge are compared with the well-known features of dc positive and negative coronas and a barrier discharge between plane electrodes. It is shown that the presence of a dielectric barrier on the plane electrode significantly changes the electric characteristics and spatial structure of the corona, whereas the main phases of the discharge evolution remain unchanged as the voltage increases. With a point electrode, the breakdown voltage of the barrier corona decreases substantially as compared to the breakdown voltage of a barrier discharge with plane electrodes. This leads to softer conditions for the streamer formation in a barrier corona, which becomes more stable against spark generation

  4. Characterization of electrical discharge machining plasmas

    OpenAIRE

    Descoeudres, Antoine; Hollenstein, Christoph

    2007-01-01

    Electrical Discharge Machining (EDM) is a well-known machining technique since more than fifty years. Its principle is to use the eroding effect on the electrodes of successive electric spark discharges created in a dielectric liquid. EDM is nowadays widely-used in a large number of industrial areas. Nevertheless, few studies have been done on the discharge itself and on the plasma created during this process. Further improvements of EDM, especially for micro-machining, require a better contr...

  5. The Electrical Characteristics of a Filamentary Dielectric Barrier Discharge

    International Nuclear Information System (INIS)

    The electrical characteristics of a filamentary dielectric barrier discharge using parallel-plate electrodes geometry were statistically studied. The DBD's system was powered by a 50 Hz power supply and operated at atmospheric pressure. The influence of the air gap and position of dielectric on the discharge had been investigated. It was found that the air gap distance and position of dielectric had significant influence on the discharge current pulse. The results showed that discharge with large distance between the high voltage electrode and the dielectric would generate higher current pulses during the positive cycle. The discharge energy of single pulse was also determined.

  6. Rapid breakdown mechanisms of open air nanosecond dielectric barrier discharges.

    Science.gov (United States)

    Ito, Tsuyohito; Kanazawa, Tatsuya; Hamaguchi, Satoshi

    2011-08-01

    The discharge initiation mechanism of nanosecond dielectric barrier discharges in open air has been clarified with time-dependent measurement of the discharge electric field by electric-field-induced coherent Raman scattering and optical emission. Our experimental observations have revealed that, in the prebreakdown phase of a nanosecond dielectric barrier discharge, the externally applied fast-rising electric field is strongly enhanced near the cathode due to large accumulation of space charge, which then strongly enhances ionization near the cathode. Once a sufficiently large number of ionizations take place, the location of peak ionization forms a front and propagates toward the cathode with strong optical emission, which establishes the discharge. This process is essentially different from the well-known Townsend mechanism for slower discharges. PMID:21902331

  7. Surface modification of nanofibrillated cellulose films by atmospheric pressure dielectric barrier discharge

    DEFF Research Database (Denmark)

    Siró, Istvan; Kusano, Yukihiro; Norrman, Kion;

    2013-01-01

    A dielectric barrier discharge in a gas mixture of tetrafluoromethane (CF4) and O2 was used for tailoring the surface properties of nanofibrillated cellulose (NFC) films. The surface chemical composition of plasma-modified NFC was characterized by means of X-ray photoelectron spectroscopy and time...

  8. Spatial and temporal distribution of excited Cl atoms in a linear dielectric barrier discharge

    International Nuclear Information System (INIS)

    This paper presents the spatial distribution of excited Cl atoms in a linear dielectric barrier discharge using diode laser atomic absorption spectrometry. Comparative measurements were performed in Ar and He with small admixtures of CCl2F2 these results being important in improving the characteristics of the plasma selective detector. (authors)

  9. Atmospheric Pressure Radio Frequency Dielectric Barrier Discharges in Nitrogen/Argon

    International Nuclear Information System (INIS)

    This work reports the experimental results on the characteristics of radio frequency dielectric barrier N2/Ar discharges. Depending on the nitrogen content in the feed gas and the input power, the discharge can operate in two different modes: a homogeneous glow discharge and a constricted discharge. With increasing input power, the number of discharge columns increases. The discharge columns have starlike structures and exhibit symmetric self-organized arrangement. Optical emission spectroscopy was performed to estimate the plasma temperature. Spatially resolved gas temperature measurements, determined from NO emission rotational spectroscopy were taken across the 4.4 mm gap filled by the discharge. Gas temperature in the middle of the gas gap is lower than that close to the electrodes

  10. A dielectric barrier discharge in neon at atmospheric pressure

    International Nuclear Information System (INIS)

    A dielectric barrier discharge in neon at atmospheric pressure is investigated with electrical measurement and fast photography. It is found that a stable diffuse discharge can be easily generated in a gap with a gap space of 0.5-6 mm and is identified with a glow discharge. The first breakdown voltage of the gap is considerably higher than that of the same gap working in a stable diffuse discharge mode, which indicates that Penning ionization of neon metastables from the previous discharge with inevitable gas impurities plays an important role in the decrease in the breakdown voltage. Discharge patterns are observed in a gap shorter than 1 mm. From the experiments with a wedge-like gap, it is found that the discharge patterns are formed in the area with a higher applied electric field, which suggests that a higher applied electric field may cause a transition from a diffuse glow to discharge patterns.

  11. Visible and VUV images of dielectric barrier discharges in Xe

    International Nuclear Information System (INIS)

    We have recorded short exposure images of visible and vacuum ultraviolet (VUV) emission from a Xe dielectric barrier discharge lamp, and investigated the effects of excitation by fast rising pulse and sinusoidal voltage waveforms on the discharge structure. The images from the pulsed discharge are essentially uniform over the active electrode area unlike the sinusoidal discharge which is filamentary. By investigating a single filament discharge, it is also found that a large fraction ((>)90%) of the total visible and VUV emission for sinusoidal excitation is generated from regions outside the filament. The images suggest that the VUV is generated from surface discharges, or 'feelers', which branch out laterally from the filaments. Model calculations suggest that surface or volume discharges, in which the current density is much lower than for filamentary discharges, generate VUV emission more efficiently due to the reduced rate for multi-step electron excitation of Xe* species. (author)

  12. Recent advances in the understanding of homogeneous dielectric barrier discharges

    OpenAIRE

    Massines, F.; Gherardi, N.; Naudé, N.; Ségur, P.

    2009-01-01

    This paper is a state of the art of the understanding on the physics of homogeneous dielectric barrier discharges at atmospheric pressure. It is based on the analysis of present and previous work about the behavior of these discharges and the conditions to get them. Mechanisms controlling the homogeneity during gas breakdown and discharge development are successively discussed. The breakdown has to be a Townsend one, the ionization has to be slow enough to avoid a large avalanche development....

  13. Recent advances in the understanding of homogeneous dielectric barrier discharges

    OpenAIRE

    Massines, F.; Gherardi, N.; Naudé, N.; Ségur, P.

    2009-01-01

    Abstract This paper is a state of the art of the understanding on the physics of homogeneous dielectric barrier discharges at atmospheric pressure. It is based on the analysis of present and previous work about the behavior of these discharges and the conditions to get them. Mechanisms controlling the homogeneity during gas breakdown and discharge development are successively discussed. The breakdown has to be a Townsend one, the ionization has to be slow enough to avoid a large av...

  14. Study on the transition from filamentary discharge to diffuse discharge by using a dielectric barrier surface discharge device

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Discharge characteristics have been investigated in different gases under different pressures using a dielectric barrier surface discharge device. Electrical measurements and optical emission spectroscopy are used to study the discharge,and the results obtained show that the discharges in atmospheric pressure helium and in low-pressure air are diffuse,while that in high-pressure air is filamentary. With decreasing pressure, the discharge in air can transit from filamentary to diffuse one. The results also indicate that corona discharge around the stripe electrode is important for the diffuse discharge. The spectral intensity of N2+ (391.4 nm) relative to N2 (337.1 nm) is measured during the transition from diffuse to filamentary discharge. It is shown that relative spectral intensity increases during the discharge transition. This phenomenon implies that the averaged electron energy in diffuse discharge is higher than that in the filamentary discharge.

  15. Model description of surface dielectric barrier discharges for flow control

    Energy Technology Data Exchange (ETDEWEB)

    Lagmich, Y; Callegari, Th; Pitchford, L C; Boeuf, J P [LAPLACE, Universite de Toulouse, CNRS, 118 route de Narbonne, 31062 Toulouse (France)

    2008-05-07

    This paper presents a study of the development of a surface dielectric barrier discharge in air under conditions similar to those of plasma actuators for flow control. The study is based on results from a 2D fluid model of the discharge in air that provides the space and time evolution of the charged particle densities, electric field and surface charges. The electrohydrodynamic (EHD) force associated with the momentum transfer from charged particles to neutral molecules in the volume above the dielectric layer is also deduced from the model. Results show that the EHD force is important not only during the positive part of the sinusoidal voltage cycle (i.e. when the electrode on top of the dielectric layer plays the role of the anode) but also during the negative part of the cycle (cathode on top of the dielectric layer). During the positive part of the cycle, the EHD force is due to the formation of a positive ion cloud that is periodically interrupted by high current breakdown. The EHD force during the negative part of the cycle is due to the development of a negative ion cloud that continuously grows during the successive high frequency current pulses that form in this regime.

  16. Influence of gap width on discharge asymmetry in atmospheric pressure glow dielectric barrier discharges

    International Nuclear Information System (INIS)

    In this letter, a one-dimensional fluid model is used to investigate the mechanism of discharge asymmetry in atmospheric pressure helium glow dielectric barrier discharges (GDBDs). By observing the evolutionary process between the successive peak currents, the effect of the gap width on the discharge asymmetry is thoroughly discussed. It is shown that when the gap width is too large, the very severe nonuniformity of electric field distribution over the gas gap leads to the discharge asymmetry.

  17. Evaluation of different dielectric barrier discharge plasma configurations as an alternative technology for green C1 chemistry in the carbon dioxide reforming of methane and the direct decomposition of methanol.

    Science.gov (United States)

    Rico, Víctor J; Hueso, José L; Cotrino, José; González-Elipe, Agustín R

    2010-03-25

    Carbon dioxide reforming of methane and direct decomposition of methanol have been investigated using dielectric barrier discharges (DBD) at atmospheric pressure and reduced working temperatures. Two different plasma reactor configurations are compared and special attention is paid to the influence of the surface roughness of the electrodes on the conversion yields in the first plasma device. The influence of different filling gap dielectric materials (i.e., Al(2)O(3) or BaTiO(3)) in the second packed configuration has been also evaluated. Depending on the experimental conditions of applied voltage, residence time of reactants, feed ratios, or reactor configuration, different conversion yields are achieved ranging from 20 to 80% in the case of methane and 7-45% for the carbon dioxide. The direct decomposition of methanol reaches 60-100% under similar experimental conditions. Interestingly, the selectivity toward the production of hydrogen and carbon monoxide is kept almost constant under all the experimental conditions, and the formation of longer hydrocarbon chains or coke as a byproduct is not detected. The maximum efficiency yields are observed for the packed-bed reactor configuration containing alumina for both reaction processes (approximately 1 mol H(2) per kilowatt hour for dry reforming of methane and approximately 4.5 mol H(2) per kilowatt hour for direct decomposition of methanol). PMID:20184329

  18. Atmospheric pressure dielectric barrier discharges interacting with liquid covered tissue

    International Nuclear Information System (INIS)

    The interaction of plasmas with liquids is of increasing importance in biomedical applications. Tissues treated by atmospheric pressure dielectric barrier discharges (DBDs) in plasma medicine are often covered by a thin layer of liquid, typically a blood serum like water with dissolved gases and proteins up to hundreds of micrometres thick. The liquid processes the plasma-produced radicals and ions prior to their reaching the tissue. In this paper, we report on a computational investigation of the interaction of DBDs in humid air with a thin water layer covering tissue. The water layer, 50–400 µm thick, contains dissolved O2aq (aq means an aqueous species) and alkane-like hydrocarbons (RHaq). In the model, the DBDs are operated with multiple pulses at 100 Hz followed by a 1 s afterglow. Gas phase reactive oxygen and nitrogen species (RONS) intersect the water-vapour saturated air above the liquid and then solvate when reaching the water. The photolysis of water by plasma-produced UV/VUV plays a significant role in the production of radicals. Without RHaq, O2aq−, ONOOaq−, NO3aq− and hydronium (H3Oaq+) dominate the water ions with H3Oaq+ determining the pH. The dominant RONS in the liquid are O3aq, H2O2aq, and HNOxaq. Dissolved O2aq assists the production of HNO3aq and HOONOaq during the afterglow. With RHaq, reactive oxygen species are largely consumed, leaving an R·aq (alkyl radical) to reach the tissue. These results are sensitive to the thickness of the water layer. (paper)

  19. Energy and force prediction for a nanosecond pulsed dielectric barrier discharge actuator

    Science.gov (United States)

    Wang, Chin-Cheng; Roy, Subrata

    2012-05-01

    A three-species physical model is presented for dielectric barrier discharge (DBD) actuator under atmospheric pressure. The governing equations are solved for temporal and spatial distribution of electric potential and charge species using the finite element based multiscale ionized gas flow code. The plasma model is loosely coupled with compressible Navier-Stokes equations through momentum and energy source terms. Two cases of rf powered and nanosecond pulsed barrier discharge actuators are simulated. Based on the imparted time average electrohydrodynamic force and power deposition to the neutral gas, the nanosecond pulsed DBD actuator creates significant pressure variations within few microseconds. These results are in reasonable agreement with recently reported experimental shadow images.

  20. Power supply instrumentation for pulsed dielectric barrier discharges

    International Nuclear Information System (INIS)

    The design and implementation of a pulsed high voltage supply intended to the production and control of pulsed dielectric barrier discharges are reported. The instrumentation includes three independently built DC sources coupled to Flyback-like converters using three 1:50 high voltage transformers. The system is capable of supplying voltages up to 70 kV at a 100-2000 Hz repetition rate, delivering 1-500 μs wide pulses. The system has been applied to the development of pulsed dielectric barrier discharges in a stainless steel coaxial reactor 30 cm long and with a 2.54 cm diameter. The inner nickel electrode diameter is 0.005 cm and is embedded in alumina. The discharges have been carried out in room pressure air. Discharges have been implemented. The discharge is made is a water environment for purposes of bacterial elimination.

  1. 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.

  2. Edge transport barriers in magnetic fusion plasmas

    International Nuclear Information System (INIS)

    The present level of understanding of the physics of the formation and sustainment of edge transport barriers in magnetically confined fusion plasmas is presented. The formation of edge transport barriers is studied through evolution of mechanisms which can suppress plasma turbulence and so reduce turbulent driven transport, such as E x B flow shear stabilization of turbulence. Comparisons of theoretical studies with experimental results are described including investigations of zonal flows, which are considered important for saturation and self-regulation of turbulence and turbulence-driven transport. Processes that affect the dynamics and spatial structure of the edge barrier are described with emphasis on the width of the transport barrier. (authors)

  3. Determination of OH radical concentration in dielectric barrier discharges by co oxidation

    International Nuclear Information System (INIS)

    H radicals play an essential role in various plasma-chemical processes aimed at removal of volatile organic compounds (VOC), NOx and SO2 from polluted off-air flows. For the optimization of OH radical generation in non-thermal plasma discharges a simple but reliable diagnostic method is useful and necessary. We report about the oxidation of carbon monoxide as a diagnostic tool for OH radical determination in dielectric barrier discharges (DBD) at atmospheric pressure. The results are discussed in terms of a simple kinetic model allowing the determination of the average OH production efficiency (GOH-value) and the OH lifetime in dependence on air flow humidity. (author)

  4. Treatment of industrial exhaust gases by a dielectric barrier discharge

    Science.gov (United States)

    Schmidt, Michael; Hołub, Marcin; Jõgi, Indrek; Sikk, Martin

    2016-08-01

    Volatile organic compounds (VOCs) in industrial exhaust gases were treated by a dielectric barrier discharge (DBD) operated with two different mobile power supplies. Together with the plasma source various gas diagnostics were used, namely fourier transform infrared (FTIR) spectroscopy, flame ionization detector (FID) and GC-MS. The analysis revealed that some exhaust gases consist of a rather complex mixture of hydrocarbons and inorganic compounds and also vary in pollutants concentration and flow rate. Thus, analysis of removal efficiencies and byproduct concentrations is more demanding than under laboratory conditions. This contribution presents the experimental apparatus used under the harsh conditions of industrial exhaust systems as well as the mobile power source used. Selected results obtained in a shale oil processing plant, a polymer concrete production facility and a yacht hull factory are discussed. In the case of total volatile organic compounds in oil processing units, up to 60% were removed at input energy of 21-37 J/L when the concentrations were below 500 mg/m3. In the yacht hull factory up to 74% of styrene and methanol were removed at specific input energies around 300 J/L. In the polymer concrete production site 195 ppm of styrene were decomposed with the consumption of 1.8 kJ/L. These results demonstrate the feasibility of plasma assisted methods for treatment of VOCs in the investigated production processes but additional analysis is needed to improve the energy efficiency. Contribution to the topical issue "6th Central European Symposium on Plasma Chemistry (CESPC-6)", edited by Nicolas Gherardi, Ester Marotta and Cristina Paradisi

  5. Study on Glow Discharge Plasma Used in Polyester Surface Modification

    Science.gov (United States)

    Liu, Wenzheng; Lei, Xiao; Zhao, Qiang

    2016-01-01

    To achieve an atmospheric pressure glow discharge (APGD) in air and modify the surface of polyester thread using plasma, the electric field distribution and discharge characteristics under different conditions were studied. We found that the region with a strong electric field, which was formed in a tiny gap between two electrodes constituting a line-line contact electrode structure, provided the initial electron for the entire discharge process. Thus, the discharge voltage was reduced. The dielectric barrier of the line-line contact electrodes can inhibit the generation of secondary electrons. Thus, the transient current pulse discharge was reduced significantly, and an APGD in air was achieved. We designed double layer line-line contact electrodes, which can generate the APGD on the surface of a material under treatment directly. A noticeable change in the surface morphology of polyester fiber was visualized with the aid of a scanning electron microscope (SEM). Two electrode structures - the multi-row line-line and double-helix line-line contact electrodes - were designed. A large area of the APGD plasma with flat and curved surfaces can be formed in air using these contact electrodes. This can improve the efficiency of surface treatment and is significant for the application of the APGD plasma in industries.

  6. Inactivation of Escherichia coli on PTFE surfaces by diffuse coplanar surface barrier discharge

    Science.gov (United States)

    Tučeková, Zlata; Koval'ová, Zuzana; Zahoranová, Anna; Machala, Zdenko; Černák, Mirko

    2016-08-01

    The non-equilibrium plasma of diffuse coplanar surface barrier discharge (DCSBD) was tested for decontamination of bacteria Escherichia coli on polymer surfaces. We investigated the optical parameters of DCSBD plasma generated in synthetic air with different relative humidity. Our study was provided to estimate the main plasma components active during the DCSBD plasma degradation of E. coli contamination prepared on polytetrafluoroethylene (PTFE, Teflon) surface, in ambient air at atmospheric pressure. The DCSBD plasma was characterized by means of electrical measurements and optical emission spectroscopy. The inactivation of E. coli bacteria was evaluated by standard microbiological cultivation (CFU plate counting). The experimental results of the germicidal efficiency obtained for short plasma exposure times proved the effectiveness of DCSBD plasma for the polymer surface decontamination. Contribution to the topical issue "6th Central European Symposium on Plasma Chemistry (CESPC-6)", edited by Nicolas Gherardi, Ester Marotta and Cristina Paradisi

  7. Flow Parameters of Argon plasma Discharge

    International Nuclear Information System (INIS)

    Owing to the viscosity, the plasma will be adhering to the inner surface of the outer electrode and outer surface of the inner one. As result that the discharge will be eroding the walls of coaxial system. The thickness of the boundary layer near the walls has been estimated at different positions from the breech of coaxial plasma gun. It is found that the thickness of layer 0.008 cm at the end of inner electrode (17 cm). A coaxial plasma gun device is operated in argon gas at ambient pressure 0.6 Torr and discharge voltage about 10 KV. The electron temperature of argon discharge has been determined by using spectroscopic technique. It is found that kTe=3.4 eV. By knowing the thickness of the boundary layer, the density can be determined. The Reynolds number R=105 and Mach number M=5 i.e. the flow is compressible and hypersonic

  8. Electrical characterization of atmospheric pressure dielectric barrier discharge in air

    International Nuclear Information System (INIS)

    This paper reports the electrical characterization of dielectric barrier discharge produced at atmospheric pressure using a high voltage power supply operating at 50Hz. The characteristics of the discharge have been studied under different values as such applied voltage and the electrode gap width. The results presented in this work can be helpful in understanding the influence of dielectric material on the nature of the discharge. An attempt has also been made to investigate the influence of ballast resistor on the magnitude of discharge current and also the density of micro-discharges. Our results indicated that with this power supply and electrode geometry, a relatively more homogenous discharge is observed for 3 mm spacing. (author)

  9. Optical Comparison of Single and Double Dielectric barrier plasma actuators

    Science.gov (United States)

    Hershkowitz, Noah; Oksuz, Lutfi; Hoskinson, Alan

    2009-11-01

    Time resolved ICCD pictures are taken for double and single surface barrier discharge plasma actuator for thick and thin powered electrodes. The filament and jet propagation minimum speeds are measured for both single and double barrier actuators. Optical emission spectra are measured using a monochromator. In a typical OES spectrum, O2, O^+, CO, OH, N, N2, N2^+ and also optical emission lines from exposed electrodes (stainless steel, copper and tungsten lines) were observed for single barrier actuators. The optical data are fit by SPECAIR code^1. The translational and rotational temperatures are found to be approximately room temperature while the vibrational temperatures were1700 K and 1200 K, the electron temperatures were 3200 K and 2400 K for thick and thin electrode respectively. The different regimes in a discharge will be discussed.

  10. The Experimental Investigations of Dielectric Barrier Discharge and Pulse Corona Discharge in Air Cleaning

    Institute of Scientific and Technical Information of China (English)

    左莉; 侯立安; 杨林松

    2003-01-01

    The dielectric barrier discharge (DBD) and pulse corona discharge(PCD) plasmagenerator was used to remove NH3, H2S, C7Hs etc. from atmosphere. The principle and charac-teristic of the two ways was discussed in the article. The test shows the result of PCD is betterthan that of DBD.

  11. 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.

  12. Sheet plasma produced by hollow cathode discharge

    International Nuclear Information System (INIS)

    A sheet plasma is produced by a hollow cathode discharge under an axial magnetic field. The plasma is about 40 cm in length, 4 cm in width and 1 cm in thickness. The electron density is about 108 cm-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

  13. Equiintensities of RF plasma discharges

    International Nuclear Information System (INIS)

    The presented diagnostic tool can provide information of temperature distribution in the plasma. The main advantage of the method is relatively simple, low cost and quick procedure. On the other hand the individual isoline corresponds to some mean values for the wide bandwidth of interference filter. However, in real plasma sources is usually difficult to find isolated intensive line which is characterized by excitation temperature. Nevertheless, we believe that application is useful and fulfills other diagnostics methods. The visualisation of temperature field can help to understand conditions in plasmas and processes occurring there. However, the fast procedure (in real time) will be useful only. It has to be done during each experiment and carefully coupled with other diagnostic methods. It means that the device must be the low cost one. (author)

  14. Collector floating potentials in a discharge plasma

    International Nuclear Information System (INIS)

    We present the results of a study on electrode floating potential formation in a hot-cathode discharge plasma. The electron component of the plasma is composed from two populations. The high temperature component develops from primary electrons and the cool component from secondary electrons born by ionisation of cold neutral gas. A static, kinetic plasma-sheath model is use to calculate the pre-sheath potential and the floating potential of the electrode. For hot primary electrons a truncated Maxwellian distribution is assumed. The plasma system is also modelled numerically with a dynamic, electrostatic particle simulation. The plasma source injects temporally equal fluxes of ions and electrons with half-Maxwellian velocities. Again, the hot electron distribution is truncated in the high velocity tail. The plasma parameters, such as ion temperature and mass, electron temperatures, discharge voltages, etc. correspond to experimental values. The experimental measurements of the electrode floating potential are performed in weakly magnetised plasma produced with hot cathode discharge in argon gas. Theoretical, simulation and experimental results are compared and they agree very well.(author)

  15. Hexagonal and honeycomb structures in Dielectric Barrier Discharges

    OpenAIRE

    Bernecker, B; Callegari, T; S. Blanco; Fournier, R.; Boeuf, J P

    2009-01-01

    Abstract We present an experimental study of pattern formation in a Dielectric Barrier Discharge in Neon at 100 torr and 1 mm gap. An intensified CCD camera is used to analyze the time evolution of the patterns during one cycle of the voltage waveform. The formation of a hexagonal pattern of filaments in a transient, glow-like regime is observed, followed by a honeycomb structure that corresponds to a Townsend discharge occurring outside the regions delimite...

  16. Spatial and temporal distribution of excited Cl atoms in a linear dielectric barrier discharge

    International Nuclear Information System (INIS)

    This paper presents results on the spatial distribution of excited Cl atoms in a linear dielectric barrier discharge (DBD) at moderate pressure using diode laser atomic absorption spectrometry. A method based on imaging the collimated diode laser beam at relatively long distance from the plasma allowed to measure the relative density of the Cl metastable 4P5/2 level with a spatial resolution in the discharge less than 100 m. Comparative measurements were performed in an Ar as well as in a He plasma with small admixtures of CCl2F2. The highest density of excited Cl atoms is produced close to the temporary cathode in Ar and it is shifted towards the middle of the discharge in He for similar discharge conditions. These results are very important in improving the characteristics of a DBD detector applied in element selective detection of molecular species. (authors)

  17. Behavior of ZnO-coated alumina dielectric barrier discharge in atmospheric pressure air

    CERN Document Server

    Li, Meng; Tao, Xiaoping

    2011-01-01

    A complete investigation of the discharge behavior of dielectric barrier discharge device using ZnO-coated dielectric layer in atmospheric pressure is made. Highly conductive ZnO film was deposited on the dielectric surface. Discharge characteristic of the dielectric barrier discharge are examined in different aspects. Experimental result shows that discharge uniformity is improved definitely in the case of ZnO-coated dielectric barrier discharge. And relevant theoretical models and explanation are presented to describing its discharge physics.

  18. Temperature profiles in filamentary dielectric barrier discharges at atmospheric pressure

    International Nuclear Information System (INIS)

    Physico-chemical properties of atmospheric pressure filamentary dielectric barrier discharges (f-DBD) depend on coupled electrical characteristics and thermal profiles. In this paper, a method for studying thermal and electrical effects is developed. Therefore, thermal profiles of f-DBD are studied for well-defined electrical characteristics of quasi-identical filaments with controlled distribution in time and space. The temperatures of gas, dielectric surface and plasma depend on the surface density and on the temporal frequency of filaments, defining the input power, and can be tuned by controlling heat transfers. Different methods to control these temperatures are depicted. Moreover, heat transfer through conduction and convection from dielectric surface is shown to be the dominant heating mechanism of the flowing gas in the reactor. Finally, experimental results show that the local temperature gradient around each filament can be controlled by the frequency of the applied voltage. Actually, the temperature difference between the filament and the surrounding gas is constant below 10 kHz but increases linearly with the frequency above 10 kHz. At high frequency, the time between two successive filaments occurring at the same position becomes smaller than the relaxation time constant of thermal exchanges (∼0.1 ms). Hence, this rise in local temperature can be attributed to time-limited heat transfers from the filament axis.

  19. Temperature profiles in filamentary dielectric barrier discharges at atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Jidenko, N; Bourgeois, E; Borra, J-P [Laboratoire de Physique des Gaz et des Plasmas (UMR 8578 CNRS-Univ Paris-Sud Orsay, F-91405) SUPELEC, Plateau Moulon, F-91192 Gif-Sur-Yvette (France)

    2010-07-28

    Physico-chemical properties of atmospheric pressure filamentary dielectric barrier discharges (f-DBD) depend on coupled electrical characteristics and thermal profiles. In this paper, a method for studying thermal and electrical effects is developed. Therefore, thermal profiles of f-DBD are studied for well-defined electrical characteristics of quasi-identical filaments with controlled distribution in time and space. The temperatures of gas, dielectric surface and plasma depend on the surface density and on the temporal frequency of filaments, defining the input power, and can be tuned by controlling heat transfers. Different methods to control these temperatures are depicted. Moreover, heat transfer through conduction and convection from dielectric surface is shown to be the dominant heating mechanism of the flowing gas in the reactor. Finally, experimental results show that the local temperature gradient around each filament can be controlled by the frequency of the applied voltage. Actually, the temperature difference between the filament and the surrounding gas is constant below 10 kHz but increases linearly with the frequency above 10 kHz. At high frequency, the time between two successive filaments occurring at the same position becomes smaller than the relaxation time constant of thermal exchanges ({approx}0.1 ms). Hence, this rise in local temperature can be attributed to time-limited heat transfers from the filament axis.

  20. Abatement of malodorants from pesticide factory in dielectric barrier discharges.

    Science.gov (United States)

    Chen, Jie; Yang, Jiantao; Pan, Hua; Su, Qingfa; Liu, Yamin; Shi, Yao

    2010-05-15

    Traditional odor control methods are limitative technically and economically for the abatement of odor from pesticide factory due to its toxicity and complicated composition. Non-thermal plasma (NTP) methods, typically characterized by high removal efficiency, energy yields and good economy, offer possible alternative solutions. This paper provides laboratory scale experimental data on the removal of simulated odors from pesticide factory with various humidity (0-0.8 vol%) and oxygen contents (0-21%) by a dielectric barrier discharge (DBD) reactor. Peak voltage and initial dimethylamine (DML) concentration are important factors that influence the DML removal efficiency and energy yield. The conversion of DML of 761 mg/m(3) reaches 100% at a peak voltage of 41.25 kV. Under the experiment conditions, the conversion of DML increases with an increase of oxygen contents. And the highest DML conversion was achieved with the gas stream containing 0.3% water. Simultaneously, the concentration of O(3) and OH radical in reactor was measured. Higher conversion, higher energy yield and fewer byproducts were found in mixed odor (DML+dimethyl sulfide (DMS)) treatment than that in single odor treatment. The energy yield is promoted from 2.13 to 5.20mg/kJ. PMID:20116170

  1. Abatement of malodorants from pesticide factory in dielectric barrier discharges

    Energy Technology Data Exchange (ETDEWEB)

    Chen Jie; Yang Jiantao; Pan Hua; Su Qingfa; Liu Yamin [Institute of Industrial Ecology and Environment, Zhejiang University (Yuquan Campus) Hangzhou 310027 (China); Shi Yao, E-mail: shiyao@zju.edu.cn [Institute of Industrial Ecology and Environment, Zhejiang University (Yuquan Campus) Hangzhou 310027 (China)

    2010-05-15

    Traditional odor control methods are limitative technically and economically for the abatement of odor from pesticide factory due to its toxicity and complicated composition. Non-thermal plasma (NTP) methods, typically characterized by high removal efficiency, energy yields and good economy, offer possible alternative solutions. This paper provides laboratory scale experimental data on the removal of simulated odors from pesticide factory with various humidity (0-0.8 vol%) and oxygen contents (0-21%) by a dielectric barrier discharge (DBD) reactor. Peak voltage and initial dimethylamine (DML) concentration are important factors that influence the DML removal efficiency and energy yield. The conversion of DML of 761 mg/m{sup 3} reaches 100% at a peak voltage of 41.25 kV. Under the experiment conditions, the conversion of DML increases with an increase of oxygen contents. And the highest DML conversion was achieved with the gas stream containing 0.3% water. Simultaneously, the concentration of O{sub 3} and OH radical in reactor was measured. Higher conversion, higher energy yield and fewer byproducts were found in mixed odor (DML + dimethyl sulfide (DMS)) treatment than that in single odor treatment. The energy yield is promoted from 2.13 to 5.20 mg/kJ.

  2. Abatement of malodorants from pesticide factory in dielectric barrier discharges

    International Nuclear Information System (INIS)

    Traditional odor control methods are limitative technically and economically for the abatement of odor from pesticide factory due to its toxicity and complicated composition. Non-thermal plasma (NTP) methods, typically characterized by high removal efficiency, energy yields and good economy, offer possible alternative solutions. This paper provides laboratory scale experimental data on the removal of simulated odors from pesticide factory with various humidity (0-0.8 vol%) and oxygen contents (0-21%) by a dielectric barrier discharge (DBD) reactor. Peak voltage and initial dimethylamine (DML) concentration are important factors that influence the DML removal efficiency and energy yield. The conversion of DML of 761 mg/m3 reaches 100% at a peak voltage of 41.25 kV. Under the experiment conditions, the conversion of DML increases with an increase of oxygen contents. And the highest DML conversion was achieved with the gas stream containing 0.3% water. Simultaneously, the concentration of O3 and OH radical in reactor was measured. Higher conversion, higher energy yield and fewer byproducts were found in mixed odor (DML + dimethyl sulfide (DMS)) treatment than that in single odor treatment. The energy yield is promoted from 2.13 to 5.20 mg/kJ.

  3. Experimental investigation of Lissajous figure shapes in planar and surface dielectric barrier discharges

    International Nuclear Information System (INIS)

    Dielectric Barrier Discharges (DBDs) operating in air at atmospheric pressure are widely employed as cold plasma sources for plasma processing and applications, in both volume and surface configurations. Surface dielectric barrier discharges, however, are mainly known for the manipulation of the boundary layer of an airflow surrounding a body, and thus for aeronautical applications. Lissajous figures, obtained by means of a high-voltage and a capacitive probes, are usually adopted for both these types of DBDs as a method for measuring the power consumption by the discharge. In this work, we propose to integrate this diagnostic tool with the measurement of current pulses, which are associated to microdischarges that usually develop in these plasmas because of the presence of the dielectric barrier. We have studied both planar and surface DBDs in presence of a continuous sinusoidal voltage feeding, and we have demonstrated that this method is promising in order to gain additional information about the discharge characteristics from the shape of the Lissajous figures

  4. Experimental investigation of Lissajous figure shapes in planar and surface dielectric barrier discharges

    Science.gov (United States)

    Biganzoli, I.; Barni, R.; Gurioli, A.; Pertile, R.; Riccardi, C.

    2014-11-01

    Dielectric Barrier Discharges (DBDs) operating in air at atmospheric pressure are widely employed as cold plasma sources for plasma processing and applications, in both volume and surface configurations. Surface dielectric barrier discharges, however, are mainly known for the manipulation of the boundary layer of an airflow surrounding a body, and thus for aeronautical applications. Lissajous figures, obtained by means of a high-voltage and a capacitive probes, are usually adopted for both these types of DBDs as a method for measuring the power consumption by the discharge. In this work, we propose to integrate this diagnostic tool with the measurement of current pulses, which are associated to microdischarges that usually develop in these plasmas because of the presence of the dielectric barrier. We have studied both planar and surface DBDs in presence of a continuous sinusoidal voltage feeding, and we have demonstrated that this method is promising in order to gain additional information about the discharge characteristics from the shape of the Lissajous figures.

  5. Plasma Beam Interaction with Negative glow discharge

    International Nuclear Information System (INIS)

    A miniature coaxial gun has been used to study the effect of the energy spectrum of the ejected plasma on the interaction with negative glow region in a normal glow discharge. The peak discharge current flow between the coaxial electrodes was 5.25 K A as a single pulse with pulse duration of 60 MUs. Investigations are carried out with argon gas at pressure 0.4 Torr. The sheath thickness of the ejected plasma from the coaxial discharge was 6 cm with different densities and energies. The spectrum of electron energy varies between 6 eV and 1 eV, while the electron density varies between 5 x 1012 cm -3 and 4x1013 cm -3. The peak velocity of the ejected plasma was 0. 8 x 105 cm sec-1 in the neutral argon atoms. Argon negative glow region used as base plasma has an electron temperature of 2.2 eV and electron density of 6.2 x107 cm-3. It had been found that the velocity of the ejected plasma decreased when it moves in the negative glow region and its mean electron temperature decreased. The results are compared with the theory of beam interaction with cold plasma

  6. Ozone production in a dielectric barrier discharge with ultrasonic irradiation

    DEFF Research Database (Denmark)

    Drews, Joanna Maria; Kusano, Yukihiro; Leipold, Frank;

    2011-01-01

    Ozone production has been investigated using an atmospheric pressure dielectric barrier discharge in pure O2 at room temperature with and without ultrasonic irradiation. It was driven at a frequency of either 15 kHz or 40 kHz. The ozone production was highly dependent on the O2 flow rate...... and the discharge power. Furthermore, powerful ultrasonic irradiation at a fundamental frequency of 30 kHz with the sound pressure level of 150 dB into the discharge can improve the ozone production efficiency, particularly when operated at the frequency of 15 kHz at the flow rate of 15 L/min....

  7. Diffuse Coplanar Surface Barrier Discharge in Nitrogen: Microdischarges Statistical Behavior

    Directory of Open Access Journals (Sweden)

    Jan Cech

    2013-01-01

    Full Text Available We studied statistical behavior of microdischarges of diffuse coplanar surface barrier discharge (DCSBD operated in nitrogen atmosphere at two input voltage regimes. We measured spectrally unresolved discharge patterns together with discharge electrical parameters using highspeed iCCD camera and digital storage oscilloscope. External synchronization enabled us to measure the discharge pattern during positive and/or negative half-period of input high voltage in the single-shotmode of operation. The comparison of microdischarges behavior during positive, negative and both half periods of input high voltage was performed for two levels of input voltage, i.e. voltage slightly above ignition voltage and high above ignition voltage (“overvoltage”. The number of microchannels crossing discharge gap was counted and compared with number of microdischarge current peaks observed during corresponding half-period of input high voltage. The relations of those incidences was shown and discussed.

  8. Wire-to-Plate Surface Dielectric Barrier Discharge and Induced Ionic Wind

    Science.gov (United States)

    Zhang, Yu; Liu, Lijuan; Li, Ben; Ouyang, Jiting

    2016-06-01

    The electrical and mechanical characteristics of the wire-to-plate surface dielectric barrier discharge and the induced ionic wind are investigated experimentally. The different temporal behaviors in positive and negative half-cycles are studied by time-resolved images. It is shown that the discharge and the light emission are generally stronger in the positive half cycle. The discharge is inhomogeneous and propagates in streamer mode; however, in the negative half-cycle, the discharge appears visually uniformly and operates in the diffuse mode. The surface discharge can produce ionic wind about several m/s above the dielectric surface. There exists an optimal width of the grounded electrode to produce a larger plasma area or active wind region. Increasing of the applied voltage or normalized dielectric constant leads to a larger wind velocity. The performance of ionic wind on flow control is visualized by employing a smoke stream. supported by National Natural Science Foundation of China (Nos. 11175017 and 11475019)

  9. Efficient decomposition of NO by ammonia radical-injection method using an intermittent dielectric barrier discharge

    Energy Technology Data Exchange (ETDEWEB)

    Yukimura, Ken [Department of Electrical Engineering, Doshisha University, Kyotanabe, Kyoto, 610-0321 (Japan)]. E-mail: kyukimur@mail.doshisha.ac.jp; Kawamura, Kensuke [Department of Electrical Engineering, Doshisha University, Kyotanabe, Kyoto, 610-0321 (Japan); Hiramatsu, Takashi [Department of Electrical Engineering, Doshisha University, Kyotanabe, Kyoto, 610-0321 (Japan); Murakami, Hiroshi [Department of Electrical Engineering, Doshisha University, Kyotanabe, Kyoto, 610-0321 (Japan); Kambara, Shinji [Department of Environmental Energy System, Gifu University, Gifu, Gifu 501-1193 (Japan); Moritomi, Hiroshi [Department of Environmental Energy System, Gifu University, Gifu, Gifu 501-1193 (Japan); Yamashita, Toru [Coal Research Laboratory, Idemitsu Kosan Co., LTD, Sodegaura, Chiba 299-0267 (Japan)

    2007-03-12

    Although many NO decomposition systems have been developed using plasmas such as dielectric barrier discharges (DBDs), corona discharges, surface discharges, glow discharges, and microwave discharges, the present system is unique on the viewpoint of the use of an intermittent one-cycle sinusoidal power source to generate DBD plasma. There are several features of the system: (1) easy control of the electric power consumed in the DBD plasma, and (2) DBD-plasma generation used only for the production of ammonia radicals. The system employs a radical injection system, where the radicals are produced in a separate discharge chamber, called radical injector, from NO flow field. This enables an efficient production of ammonia radicals being appropriate for DeNOx. It is shown from the temperature dependence of NO removal (DeNOx) characteristics that the present system is a low-temperature DeNOx system compared to a conventional thermal DeNOx system, and NO decomposition is performed over a wide range of gas temperature containing NO. Surveying parametric characteristics of DeNOx, the energy efficiency is improved by a factor of 30% compared to the previously obtained result.

  10. Plasma Density Distribution Profile in Toroidal Discharge

    International Nuclear Information System (INIS)

    Tokamak is an electrode less toroidal plasma discharge system whichcontains and heats the plasma by using magnetic field and heating system suchas RF and neutral beams respectively. Using the system, tokamak is expectedto be a most advanced facility in fusion reactor concept. The importantparameters in tokamak are plasma current, plasma discharge voltage,temperature and density, plasma density profile and confinement time.However, the facility belonged to this center (P3TM) is very simple thatmeans a toroidal discharge without confinement magnetic filed and anadditional heating. The preceding result showed that it had been obtainedsome important parameters such as plasma current, discharge current, plasmavoltage and induced poloidal magnetic field. While plasma temperature andplasma density and its profile have not been observed. The one of somediagnostics to be used to determine this parameter is a Langmuir probe.Langmuir probe is an oldest diagnostic tool, simple and quite easy to bemade. The most advantage by using this probe is its ability to measure thecurrent locally. In this experiment, the home made Langmuir probe is atungsten wire with 0.8 mm in diameter enveloped by glass tube and inserted intorus tube. The torus is operated at 1 mbar argon gas pressure and 7.5 kVoperating voltage. The power source is a 330006 Maxwell type capacitor with15 micro farad, and charging system is a 825-100 Hipotronics model which canhold 20 kV of voltage and deliver 100 mA of current. The experiment resultshowed that the relative radial density profile has an exponential relationwith the approaching function is nrel ∝ e-0.54r, r isradial position. (author)

  11. Atmospheric Pressure Dielectric Barrier Discharges: A Low-Cost System for Surface Modification

    International Nuclear Information System (INIS)

    Plasma treatment is a common way for modifying the surface of a material. A simple but effective source for a low-temperature nonequilibrium plasma is dielectric barrier discharges (DBDs), also referred to as silent discharges. DBDs are characterized by the presence of at least one insulating (dielectric) layer in the discharge gap between two metal electrodes. When a high voltage is applied to the DBD configuration, tiny breakdown channels are formed in the discharge gap. These microdischarges are characterized as a weakly ionized plasma containing electrons with energies up to 10 eV and ions at room temperature. The energetic electrons provide an effective tool for chemical surface modification. Typical setups for DBD treatments consist of vacuum chambers and vacuum equipment, and so are very cost-intensive. Atmospheric pressure discharges provide a possibility for low-cost surface chemistry, because the setup consists only of the discharge set-up in normal air or in a specified inert gas atmosphere and a high-voltage amplifier coupled with a frequency generator. Silent discharges in air increase the wettability of polymer foils such as PTFE and FEP, sufficient for cell growth and further for surface-chemical binding of proteins onto the polymer. Thereby a simple and low-cost process to achieve protein chips for biomedical applications may be envisaged

  12. Dynamics behavior of homogeneous dielectric barrier discharge at atmospheric pressure

    Science.gov (United States)

    Zhang, Yan; Gu, Biao; Wang, Wenchun; Wang, Dezhen; Peng, Xuwen

    2009-07-01

    An experimental study on the dynamics behavior of homogeneous dielectric barrier discharge (HDBD) at atmospheric pressure is described in this paper. Two kinds of discharge mode, glow and Townsend discharge modes, can be easily identified according to the differential conductivity of current-voltage relationship in the ascent stage of discharge current for the atmospheric HDBD. A (three-dimensional) 3D phase space made by discharge current, gas gap voltage, and charge density of dielectric-plate surface was utilized in the study. By projecting the discharge evolution trajectory in the 3D space, the 3D trajectory of multiple current peaks discharge in atmospheric helium shows a limited cycle with convolutions and undergoes a series of bifurcation process; however, the 3D trajectory of atmospheric N2 HDBD is a limited cycle without any convolution and bifurcation process. In addition, the first ionization coefficient of working gas plays a key role to determine the discharge mode of atmospheric HDBD, the transition of discharge mode and the dynamics stability of atmospheric HDBD.

  13. Modelling of the homogeneous barrier discharge in helium at atmospheric pressure

    CERN Document Server

    Golubovskii, Y B; Behnke, J; Behnke, J F

    2003-01-01

    Numerical calculations of spatio-temporal characteristics of the homogeneous barrier discharge in helium are performed by means of a one-dimensional fluid model. The influence of the elementary processes on the discharge behaviour is studied by variation of the corresponding rate constants. The simulation and the analytical interpretation are carried out for two basic modes of the homogeneous barrier discharge, i.e. the Townsend and glow modes. The Townsend discharge is characterized by the absence of quasineutral plasma; several current peaks may occur during the half-cycle. The oscillations of the current are caused by a lag between the ion production nearby the anode and the subsequent ion-electron emission on the cathode. The specificity of the glow discharge is the development of a cathode region and a positive column during the breakdown, as well as the presence of quasineutral plasma in subsequent phases. The positive column occurs because the shielding of the external field by the plasma is not instan...

  14. Performance of Ca1-xSrxTiO3 as barriers in dielectric barrier discharges with different Sr content

    International Nuclear Information System (INIS)

    Plasma assisted catalytic technology, which uses synergetic technologies between the catalyst and plasma, has attracted much attention over the past several years. Theoretically, permittivity of a dielectric barrier influences the transferred charge of a microdischarge; thus high permittivity can improve the plasma reaction in a dielectric barrier discharge (DBD) plasma reactor. Despite the increased interest in the chemical processes, very little has been reported concerning the influence of materials of a dielectric barrier on DBD plasma reactions, since a high permittivity barrier generally exhibits low fracture strength and low dielectric strength making it break down under strong current pulses. In the present study, Ca1-xSrxTiO3 (0.1 ≤ x ≤ 0.4) which possesses a high permittivity and a high fracture strength was prepared by liquid phase sintering and was used as a dielectric barrier for the destruction of carbon dioxide by a DBD plasma reaction. The permittivity of Ca1-xSrxTiO3 (0.1 ≤ x ≤ 0.4) increased with increasing SrTiO3 content; however, the observed CO2 conversion became greatest using Ca0.8Sr0.2TiO3 and then decreased with increasing SrTiO3 content. These results imply that the reactivity of CO2 destruction does not monotonously increase with increased permittivity of the Ca1-xSrxTiO3 barriers. Both amplitude and density of the current pulses ignited by Ca0.8Sr0.2TiO3 were much greater than that of Ca0.6Sr0.4TiO3. Further, it was confirmed that a plasma reaction uniformly proceeded using the Ca0.8Sr0.2TiO3 barrier, but proceeded non-uniformly using the Ca0.6Sr0.4TiO3 barrier by observing the carbon deposition profiles on the surfaces of the barriers

  15. On electric field measurements in surface dielectric barrier discharge

    OpenAIRE

    Starikovskaia, S M; Allegraud, K; Guaitella, O; Rousseau, A.

    2010-01-01

    Abstract Analysis of available data on electric field measurements in surface dielectric barrier discharges (DBDs) was carried out. Experimental measurements of emission spectra in triggered and non?triggered sinusoidal surface DBD were performed. The obtained results were used for the calculation of electric field value. The comparison of data obtained and the results published by other authors is presented.

  16. On electric field measurements in surface dielectric barrier discharge

    Energy Technology Data Exchange (ETDEWEB)

    Starikovskaia, S M; Allegraud, K; Guaitella, O; Rousseau, A, E-mail: svetlana.starikovskaya@lpp.polytechnique.f [Laboratoire de Physique des Plasmas, Ecole Polytechnique, Route de Saclay, 91128 Palaiseau Cedex (France)

    2010-03-31

    Analysis of available data on electric field measurements in surface dielectric barrier discharges (DBDs) was carried out. Experimental measurements of emission spectra in triggered and non-triggered sinusoidal surface DBD were performed. The results obtained were used for the calculation of electric field value. The comparison of data obtained and the results published by other authors is presented.

  17. Dielectric barrier discharge: Critical evaluation of a novel AAS atomizer

    Czech Academy of Sciences Publication Activity Database

    Kratzer, Jan; Svoboda, Milan; Boušek, J.; Mester, Z.; Sturgeon, R. E.; Dědina, Jiří

    Praha, 2014. s. 102-102. ISBN 978-80-905704-1-2. [European Symposium on Atomic Spectrometry ESAS 2014 & Czech-Slovak Spectroscopic Conference /15./. 16.03.2014-21.03.2014, Praha] R&D Projects: GA AV ČR(CZ) M200311202 Institutional support: RVO:68081715 Keywords : dielectric barrier discharge * bismuthine * atomic absorption spectrometry Subject RIV: CB - Analytical Chemistry, Separation

  18. Experimental Study on Spiral Patterns in Dielectric Barrier Discharge System

    Institute of Scientific and Technical Information of China (English)

    LIU Shu-Hua; DONG Li-Fang; LIU Fu-Cheng; LI Shu-Feng; LI Xue-Chen; WANG Hong-Fang

    2006-01-01

    Spiral patterns are obtained in a dielectric barrier discharge system with water electrodes. The dynamics of spiral formation and transition is investigated. Wavelength characteristic of spiral patterns is also studied. Correlation measurements indicate that the wavelength of spiral pattern increases with the increasing gas gap width and oscillates with the increasing drive frequency.

  19. Discussion of fundamental processes in dielectric barrier discharges used for soft ionization

    International Nuclear Information System (INIS)

    Permanent need for simple to apply and efficient methods for molecular mass spectrometry resulted in the development of a variety of methods now commonly termed ambient desorption/ionization mass spectrometry (ADI-MS), which experienced a very rapid development during the last 10 years. The most widely used techniques are direct analysis in real time (DART), plasma assisted desorption/ionization (PADI), flowing afterglow-atmospheric pressure glow discharge ionization (FA-APGDI), low-temperature plasma probe (LTP) and dielectric barrier discharge ionization (DBDI). They all share the advantage of direct, ambient analysis of samples with little or no pretreatment, and employ some kind of electrical discharge to desorb and ionize the analyte species. However, the investigations focused on the characterization, examination and understanding of underlying ionization mechanisms of these discharges are relatively small in number. More efforts are clearly needed in this segment, since the understanding of the fundamentals of these discharges is a prerequisite for optimization of working parameters of ADI-MS sources with the aim of increasing ionization efficiency. Here, ADI-MS techniques will be overviewed, with the emphasis put on the review and the analysis of the recent progress in dielectric barrier discharges utilized for soft ionization. - Highlights: • Recent progress in the field of DBDs as soft ionization sources was reviewed. • Fundamentals of underlying ionization mechanisms of DBDI sources were analyzed. • Working parameters of DBDI sources that increase ionization efficiency were inspected

  20. Discussion of fundamental processes in dielectric barrier discharges used for soft ionization

    Energy Technology Data Exchange (ETDEWEB)

    Horvatic, Vlasta, E-mail: blecic@ifs.hr [Institute of Physics, Bijenicka 46, 10000 Zagreb (Croatia); Vadla, Cedomil [Institute of Physics, Bijenicka 46, 10000 Zagreb (Croatia); Franzke, Joachim [ISAS—Leibniz Institut für analytische Wissenschaften, Bunsen-Kirchhoff-Str. 11, 44139 Dortmund (Germany)

    2014-10-01

    Permanent need for simple to apply and efficient methods for molecular mass spectrometry resulted in the development of a variety of methods now commonly termed ambient desorption/ionization mass spectrometry (ADI-MS), which experienced a very rapid development during the last 10 years. The most widely used techniques are direct analysis in real time (DART), plasma assisted desorption/ionization (PADI), flowing afterglow-atmospheric pressure glow discharge ionization (FA-APGDI), low-temperature plasma probe (LTP) and dielectric barrier discharge ionization (DBDI). They all share the advantage of direct, ambient analysis of samples with little or no pretreatment, and employ some kind of electrical discharge to desorb and ionize the analyte species. However, the investigations focused on the characterization, examination and understanding of underlying ionization mechanisms of these discharges are relatively small in number. More efforts are clearly needed in this segment, since the understanding of the fundamentals of these discharges is a prerequisite for optimization of working parameters of ADI-MS sources with the aim of increasing ionization efficiency. Here, ADI-MS techniques will be overviewed, with the emphasis put on the review and the analysis of the recent progress in dielectric barrier discharges utilized for soft ionization. - Highlights: • Recent progress in the field of DBDs as soft ionization sources was reviewed. • Fundamentals of underlying ionization mechanisms of DBDI sources were analyzed. • Working parameters of DBDI sources that increase ionization efficiency were inspected.

  1. Pattern formation in dielectric barrier discharges with different dielectric materials

    International Nuclear Information System (INIS)

    The influence of dielectric material on the bifurcation and spatiotemporal dynamics of the patterns in dielectric barrier discharge in argon/air at atmospheric pressure is studied. It is found that pattern bifurcation sequences are different with different dielectric materials. The spatiotemporal dynamics of the hexagonal pattern in dielectric barrier discharge depends on the dielectric material. The hexagon pattern with glass dielectric is an interleaving of two rectangular sublattices appearing at different moments. The hexagon pattern with quartz dielectric is composed of one set of hexagonal lattice discharging twice in one half cycle of the applied voltage, one is at the rising edge and the other at the falling edge. It results in that the accumulation of wall charges in individual microdischarges in a hexagon pattern with quartz dielectric is greater than that with glass dielectric, which is in agreement with the electron density measurement by Stark broadening of Ar I 696.54 nm.

  2. A powerful electrohydrodynamic flow generated by a high-frequency dielectric barrier discharge in a gas

    Energy Technology Data Exchange (ETDEWEB)

    Nebogatkin, S. V.; Rebrov, I. E.; Khomich, V. Yu.; Yamshchikov, V. A., E-mail: yamschikov52@mail.ru [Russian Academy of Sciences, Institute for Electrophysics and Electric Power (Russian Federation)

    2016-01-15

    Theoretical and experimental studies of an electrohydrodynamic flow induced by a high-frequency dielectric barrier discharge distributed over a dielectric surface in a gas have been conducted. Dependences of the ion current, the gas flow velocity, and the spatial distributions thereof on the parameters of the power supply of the plasma ion emitter and an external electric field determined by the collector grid voltage have been described.

  3. Comparison of dielectric barrier discharge modes fungicidal effect on candida albicans growth

    International Nuclear Information System (INIS)

    Filamentary and quasi-homogeneous mode of dielectric barrier discharge (DBD) was investigated as a plasma source with fungicidal effect on Candida albicans yeast inoculated on Sabouraud agar wafers. As compared with the filamentary DBD mode, the quasi-homogeneous mode had significantly better results: shorter exposition time needed for inhibiting C. albicans yeast, moreover the quasi-homogeneous mode had gentle influence on the agar surface structure.

  4. [Temporal behavior of light emission of dielectric barrier discharges in air at atmospheric pressure].

    Science.gov (United States)

    Yin, Zeng-qian; Dong, Li-fang; Han, Li; Li, Xue-chen; Chai, Zhi-fang

    2002-12-01

    The experimental setup of dielectric barrier discharge was designed which is propitious to optical measurement. Temporal behavior of light emission of dielectric barrier discharges (filamentary model) in air at atmospheric pressure was measured by using optical method. Temporal behavior of dielectric barrier discharges was obtained. The experimental results show that the discharge burst in each half cycle of applied voltage consists of a series of discharge pulses, the duration of each discharge pulse is about 30-50 ns, and the interval of the neighboring discharge pulses is about a few hundred ns. The result is of great importance to the application of dielectric barrier discharges. PMID:12914154

  5. Plasma foundation in a pseudospark discharge

    International Nuclear Information System (INIS)

    This paper reports that unique features associated with the hollow cathode recess in a pseudospark discharge have been identified from streak camera observations. A plasma is observed to form in a highly localized region immediately behind the cathode aperture prior to gas breakdown in the main discharge volume. The point-like plasma expands from an initial diameter of below 0.3 to 3 mm, the size of the cathode aperture, in about 20 ns, at which time the main discharge is formed starting from the axis. Numerical modeling based on swarm parameters has been carried out to investigate the plasma formation in the hollow cathode region. Results show that a combination of varying ionization rates due to the field geometry and differing mobilities of electrons and ions leads to the formation of a highly localized space-charge field on axis behind the hollow cathode. This space-charge field in turn brings about the rapid formation of a highly localized, high density of charge carriers behind the cathode aperture. The authors suggest that this point-like formation of a plasma source is the phenomenon observed in the streak camera observation of the hollow cathode region

  6. Electrohydrodynamic force and scaling laws in surface dielectric barrier discharges

    International Nuclear Information System (INIS)

    The electrohydrodynamic force generated by surface dielectric barrier discharges is analyzed with a fluid mode under conditions where the electrode above the dielectric surface is the anode.. The calculated current is composed of successive large pulses associated with filamentary discharges spreading along the dielectric surface, separated by low current periods where the discharge is in a transient 'coronalike' regime. The contribution of the corona discharges to the overall force is by far dominant. An important result is that the extension of the region above the surface where the electrohydrodynamic force is significant depends on the product of the dielectric layer capacitance and the rate of voltage increase (spatial extension is larger when this parameter is smaller), but that the total, integrated force is not very sensitive to these parameters

  7. Excitation temperatures of atmospheric argon in dielectric barrier discharges

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Yu; Wen Xiaohui; Yang Weihong [CAS Key Laboratory of Basic Plasma Physics and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2007-08-15

    A method for the determination of excitation temperatures based on optical emission spectroscopy and Fermi-Dirac distribution was set up and experiments were performed on atmospheric argon dielectric barrier discharges. Local thermodynamic equilibrium was proved to exist in the discharge and the validity of Boltzmann distribution is discussed. The main aim of this paper is to obtain the temperatures of atmospheric Ar II as a function of the discharge voltage, discharge frequency, argon flow rate and the argon fraction. It was found that the excitation temperatures are in the range 3800-4950 K. Besides, an increase in the argon flow rate resulting in a slight growth of the temperature and the add-in of air leading to the decrease in temperature was observed.

  8. Equation of Energy Injection to a Dielectric Barrier Discharge Reactor

    Science.gov (United States)

    Yao, Shuiliang; Weng, Shan; Jin, Qi; Han, Jingyi; Jiang, Boqiong; Wu, Zuliang

    2016-08-01

    The electric energy injection from a pulsed power supply to a planar type of dielectric barrier discharge (DBD) reactor at atmospheric pressure was studied. Relations of the energy injection with barrier materials, barrier thickness, peak voltage, gap distance, electrode area, and operation temperature were experimentally investigated. The energy injection is a function of relative permittivity, barrier thickness, peak voltage, gap distance, and electrode area. The influence of operation temperature on energy injection is slight in the range of 27–300 °C but becomes obvious in the range of 300–500 °C. A model was established using which the energy injection can be easily predicted. supported by National Natural Science Foundation of China (No. 11575159), Zhejiang Provincial Natural Science Foundation of China (No. LY13B070004), Program for Zhejiang Leading Team of S&T Innovation (No. 2013TD07), and National Natural Science Foundation of China (No. 51206146)

  9. The influence of gas composition in dielectric barrier discharges on the broadening of the hydrogen Hα transition

    International Nuclear Information System (INIS)

    Line profiles of the Hα transition emitted from dielectric barrier discharges exhibit large broadening. This can be related to the Stark effect, taking place in plasmas and leading to broadening and shift of spectral lines due to interaction of the emitter with electric fields. These fields may originate from charged particles in the plasma as well as from external sources. The first mentioned source is dominating in the case of plasmas in thermal equilibrium or being close to such state. In inhomogeneous, non-equilibrium, and pulsed plasmas external electric field sources may dominate over the 'internal' micropoles of the plasma. In the case of dielectric barrier discharges the external electric fields are indeed the dominating agents for the formation of the Hα transition. Applying an experimental setup for polarization sensitive measurements, Hα line profiles have been measured from dielectric barrier discharges using two gas mixtures: H2+Ar and H2+He. The analysis of measured spectra, which takes into account the splitting of Stark components, allows determining the 'external' field strengths in the discharge volume. The differences between Hα line profiles obtained in both gas mixtures may be explained in terms of different interactions of hydrogen molecules and atoms with noble gas atoms. The determined field strengths acting on the emitter (hydrogen atom) may be applied for modeling of dielectric barrier discharges. (author)

  10. Influence of gas discharge parameters on emissions from a dielectric barrier discharge excited argon excimer lamp

    OpenAIRE

    Mike Collier; Erich Rohwer; Timo Stehmann; Hubertus M. von Bergmann; Dumisani J. Hlatywayo; Peter Baricholo

    2011-01-01

    A dielectric barrier discharge excited neutral argon (Ar I) excimer lamp has been developed and characterised. The aim of this study was to develop an excimer lamp operating at atmospheric pressure that can replace mercury lamps and vacuum equipment used in the sterilisation of medical equipment and in the food industry. The effects of discharge gas pressure, flow rate, excitation frequency and pulse width on the intensity of the Ar I vacuum ultraviolet (VUV) emission at 126 nm and near infra...

  11. Nonstationary effects in ozone generation by barrier discharges in N2/O2 mixtures

    Science.gov (United States)

    Zosimov, A. V.; Lunin, V. V.; Samoilovich, V. G.; Abramovskaya, E. A.; Mankelevich, Yu. A.; Poroykov, A. Yu.; Rakhimova, T. V.; Voloshin, D. G.

    2016-08-01

    The yield of ozone in barrier discharges in oxygen-nitrogen mixtures containing 0.001 to 40% of nitrogen is investigated experimentally. Phenomena of the nonstationarity of processes of ozone generation that differ from the known ozone-zero phenomenon (OZP) apparent in the reduced efficiency of ozone generation in very high purity oxygen at long periods (from hours to tens of hours) of ozonator operation are found. It is established that the characteristic times (from minutes to tens of minutes) of ozone attaining stationary values after changes in the discharge parameters indicate slow adjustment of the surface condition of insulators and thus the heterogeneous decay of ozone to more rapidly changing flows of neutral and charged particles from gas discharge plasma on the surfaces of dielectrics. The possibility of such a scenario is confirmed using a new analytical approach and numerical calculations of the plasma-chemical kinetics of N2/O2 mixtures presented in the accompanying theoretical study.

  12. Demonstration of organic volatile decomposition and bacterial sterilization by miniature dielectric barrier discharges on low-temperature cofired ceramic electrodes

    Science.gov (United States)

    Kim, Duk-jae; Shim, Yeun-keun; Park, Jeongwon; Kim, Hyung-jun; Han, Jeon-geon

    2016-04-01

    Nonthermal atmospheric-pressure plasma discharge is designed with low-temperature cofired ceramic (LTCC) electrodes to achieve dielectric barrier surface discharge (DBSD). The environmental requirement (below 0.05 ppm) of the amount of byproducts (ozone and NO x ) produced during the process was met by optimizing the electrode design to produce a high dielectric barrier discharge for low-voltage (∼700 V) operation and minimizing the distance between electrodes to improve the plasma discharging efficiency. The concentrations of volatile organic compounds (VOCs) within interior cabins of commercial vehicles were significantly reduced after 1-h treatment to improve air quality cost-effectively. This atmospheric-pressure plasma process was demonstrated for the sterilization of Escherichia coli to prevent food poisoning during the preservation of food in refrigerators.

  13. Handheld Flyback driven coaxial dielectric barrier discharge: Development and characterization

    International Nuclear Information System (INIS)

    The development of a handheld single and triple chamber atmospheric pressure coaxial dielectric barrier discharge driven by Flyback circuitry for helium and argon discharges is described. The Flyback uses external metal-oxide-semiconductor field-effect transistor power switching technology and the transformer operates in the continuous current mode to convert a continuous dc power of 10-33 W to generate a 1.2-1.6 kV 3.5 μs pulse. An argon discharge breakdown voltage of ∼768 V is measured. With a 50 kHz, pulse repetition rate and an argon flow rate of 0.5-10 argon slm (slm denotes standard liters per minute), the electrical power density deposited in the volume discharge increases linearly at a rate of 75±20% mW/cm3 per 1 slm of gas. Electrical power transfer efficiency between the secondary Flyback coil and the discharge volume increases from 0.1% to 0.65%. Neutral argon gas forced convection analysis yields a similar energy loss rate to the electrical discharge process. Optical emission spectroscopy studies of the expanding discharge plume into ambient air reveal that the air climatically controls the plume chemistry to produce an abundance of neutral argon atoms and molecular nitrogen.

  14. Handheld Flyback driven coaxial dielectric barrier discharge: Development and characterization.

    Science.gov (United States)

    Law, V J; Milosavljević, V; O'Connor, N; Lalor, J F; Daniels, S

    2008-09-01

    The development of a handheld single and triple chamber atmospheric pressure coaxial dielectric barrier discharge driven by Flyback circuitry for helium and argon discharges is described. The Flyback uses external metal-oxide-semiconductor field-effect transistor power switching technology and the transformer operates in the continuous current mode to convert a continuous dc power of 10-33 W to generate a 1.2-1.6 kV 3.5 micros pulse. An argon discharge breakdown voltage of approximately 768 V is measured. With a 50 kHz, pulse repetition rate and an argon flow rate of 0.5-10 argon slm (slm denotes standard liters per minute), the electrical power density deposited in the volume discharge increases linearly at a rate of 75+/-20% mW/cm(3) per 1 slm of gas. Electrical power transfer efficiency between the secondary Flyback coil and the discharge volume increases from 0.1% to 0.65%. Neutral argon gas forced convection analysis yields a similar energy loss rate to the electrical discharge process. Optical emission spectroscopy studies of the expanding discharge plume into ambient air reveal that the air climatically controls the plume chemistry to produce an abundance of neutral argon atoms and molecular nitrogen. PMID:19044446

  15. Electrical generators driving microhollow and dielectric barrier discharges applied for analytical chemistry.

    Science.gov (United States)

    Heming, R; Michels, A; Olenici, S B; Tombrink, S; Franzke, J

    2009-10-01

    Scaling down the size of plasma discharges would reduce the amount of gases, liquids, and consumables required, which in turn would decrease the operating costs. Nevertheless, the application of a specialized plasma generator for microhollow cathode discharges (MHCD) and dielectric barrier discharges are driven with commercially available power sources. Those generators are bulky and expensive and their overall efficiency is poor. This work develops and explains several circuit topologies and design hints to excite MHCD and dielectric barrier discharge (DBD) plasmas with respect to its system with as low as possible input power in a very efficient way. Benefits in sensitivity and life expectancy are shown. The generator for the MHCD needs voltages up to 7 V and consumes up to 5 W. The DBD generator has an input power of 3 W and produces a fast rising output pulse up to 9 kV, which has a time duration of 2 micros. These low-power circuits offer the operation with batteries. PMID:19333583

  16. Particle simulation of mode transition in dielectric barrier discharges at different gas pressures

    International Nuclear Information System (INIS)

    The dielectric barrier discharges (DBDs) at different gas pressures are investigated by use of two-dimensional particle-in-cell simulation with Monte Carlo collisions included. The pressure-dependent transition from Townsend to filamentary discharge operating in a glow regime has been demonstrated. In the filamentary discharge, four different phases are distinguished: a Townsend phase, a space-charge dominated avalanche phase, a cathode-layer formation, and a decay phase. The evolution of the electric fields, plasma densities, kinetic energy distributions, filament diameters, and breakdown voltages associated with different discharges has been presented. The above simulation results are in good agreement with previous experimental observations, suggesting that such simulation may provide guidance for the control of DBDs. (paper)

  17. Comparative study of pulsed corona and dielectric barrier discharges using single-streamer modeling and NO decomposition experiment

    International Nuclear Information System (INIS)

    A single-streamer modeling is carried out to compare the the characteristics of non-the pulsed equilibrium plasmas in the pulsed corona and dielectric barrier discharges. The numerical simulation predicts that the pulsed corona discharge is more efficient for generating N species whereas the dielectric barrier discharge is more effective for generating O species. NO decomposition experiments are then in order to verify such numerical predictions and find the influence of the steamer characteristics on the generation of chemically active species. (author)

  18. Plasma-discharge control in fluidics

    Czech Academy of Sciences Publication Activity Database

    Tesař, Václav; Šonský, Jiří

    Praha: Ústav termomechaniky AV ČR, v. v. i., 2015 - (Šimurda, D.; Bodnár, T.), s. 221-236 ISBN 978-80-87012-55-0. ISSN 2336-5781. [Topical Problems of Fluid Mechanics 2015. Praha (CZ), 11.02.2015-13.02.2015] R&D Projects: GA ČR GA13-23046S Institutional support: RVO:61388998 Keywords : fluidics * plasma dicharge * dielectric barrier Subject RIV: BK - Fluid Dynamics

  19. Influence of surface charges on the structure of a dielectric barrier discharge in air at atmospheric pressure: experiment and modeling

    OpenAIRE

    Celestin, S.; Bonaventura, Z.; Guaitella, O; Rousseau, A.; A. Bourdon

    2009-01-01

    Abstract Dielectric barrier discharges (DBD) in air at atmospheric pressure and at low frequency are mainly constituted of thin transient plasma filaments (or microdischarges) with radii of a few hundreds of micrometers. In this work, we consider a point-to-plane geometry with the dielectric covering the plane electrode. Plasma filaments are initiated by streamers, starting from the high-field region close to the point electrode. The plasma filaments deposit charges on the ...

  20. Characterization of dielectric barrier discharge in air applying current measurement, numerical simulation and emission spectroscopy

    CERN Document Server

    Rajasekaran, Priyadarshini; Awakowicz, Peter

    2012-01-01

    Dielectric barrier discharge (DBD) in air is characterized applying current measurement, numerical simulation and optical emission spectroscopy (OES). For OES, a non-calibrated spectrometer is used. This diagnostic method is applicable when cross-sectional area of the active plasma volume and current density can be determined. The nitrogen emission in the spectral range of 380 nm- 406 nm is used for OES diagnostics. Electric field in the active plasma volume is determined applying the measured spectrum, well-known Frank-Condon factors for nitrogen transitions and numerically- simulated electron distribution functions. The measured electric current density is used for determination of electron density in plasma. Using the determined plasma parameters, the dissociation rate of nitrogen and oxygen in active plasma volume are calculated, which can be used by simulation of the chemical kinetics.

  1. Conduction heat transfer in a cylindrical dielectric barrier discharge reactor

    Energy Technology Data Exchange (ETDEWEB)

    Sadat, H. [Laboratoire d' Etudes Thermiques, Universite de Poitiers, 40 Avenue du Recteur Pineau, 86022 Poitiers (France)], E-mail: hamou.sadat@univ-poitiers.fr; Dubus, N. [Laboratoire d' Etudes Thermiques, Universite de Poitiers, 40 Avenue du Recteur Pineau, 86022 Poitiers (France); Pinard, L.; Tatibouet, J.M.; Barrault, J. [Laboratoire en catalyse et chimie organique, Universite de Poitiers, 40 Avenue du Recteur Pineau, 86022 Poitiers (France)

    2009-04-15

    The thermal behaviour of a dielectric barrier discharge reactor is studied. The experimental tests are performed on a laboratory reactor with two working fluids: helium and air. A simple heat conduction model for calculating the heat loss is developed. By using temperature measurements in the internal and external electrodes, a thermal resistance of the reactor is defined. Finally, the percentage of the input power that is dissipated to the environment is given.

  2. Temperature profiles in filamentary dielectric barrier discharges at atmospheric pressure

    OpenAIRE

    Jidenko, N; Bourgeois, E; Borra, J-P

    2010-01-01

    Abstract The physico-chemical properties of atmospheric pressure filamentary Dielectric Barrier Discharge (f-DBD) depend on its electrical characteristics and thermal profile. In this paper, a method for separating thermal and electrical effects is developed. Therefore, thermal profiles of f-DBD are studied for well defined electrical characteristics of filaments: all filaments are quasi identical with a controlled spatio-temporal density. The temperatures of gas, dielectric surface and pl...

  3. Safety assessment of discharge chute isolation barrier preparation and installation

    International Nuclear Information System (INIS)

    The safety assessment is made for the activities for the preparation and installation of the discharge chute isolation barriers. The safety assessment includes a hazard assessment and comparison of potential accidents/events to those addressed by the current safety basis documentation. No significant hazards were identified. An evaluation against the USQ evaluation questions were made and the determination made that the activities do not represent a USQ. Hazard categorization techniques were used to provide a basis for readiness review classification

  4. An experimental study of atmospheric pressure dielectric barrier discharge (DBD) in argon

    Energy Technology Data Exchange (ETDEWEB)

    Subedi, D. P. [Department of Natural Sciences, School of Science, Kathmandu University, Dhulikhel (Nepal); Tyata, R. B. [Department of Natural Sciences, School of Science, Kathmandu University, Dhulikhel, Nepal and Department of Electrical, Khwopa College of Engineering, Libali-2, Bhaktapur (Nepal); Shrestha, R. [Department of Natural Sciences, School of Science, Kathmandu University, Dhulikhel, Nepal and Department of Physics, Basu College, Kalighat, Byasi, Bhaktapur (Nepal); Wong, C. S. [Plasma Technology Research Centre, Physics Department, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2014-03-05

    In this paper, experimental results on atmospheric pressure argon dielectric barrier discharge (DBD) have been presented. The discharge was generated using a high voltage (0 to 20 kV) power supply operating at frequency of 10 to 30 kHz and was studied by means of electrical and optical measurements. A homogeneous and steady discharge was observed between the electrodes with gap spacing from 1 mm to 3 mm and with a dielectric barrier of thickness 1.5 mm while argon gas is fed at a controlled flow rate of 2liter per min. The electron temperature (T{sub e}) and electron density (n{sub e}) of the plasma have been determined by means of optical emission spectroscopy. Our results show that the electron density is of the order of 10{sup 16} cm{sup −3} while the electron temperature is estimated to be ∼ 1 eV. The homogeneity and non-thermal nature of the discharge were utilized in the investigation of the change in wettabilty of a polymer sample subjected to the treatment by the discharge. Contact angle analysis showed that the discharge was effective in improving the wettability of low density Polyethylene (LDPE) polymer sample after the treatment.

  5. An experimental study of atmospheric pressure dielectric barrier discharge (DBD) in argon

    International Nuclear Information System (INIS)

    In this paper, experimental results on atmospheric pressure argon dielectric barrier discharge (DBD) have been presented. The discharge was generated using a high voltage (0 to 20 kV) power supply operating at frequency of 10 to 30 kHz and was studied by means of electrical and optical measurements. A homogeneous and steady discharge was observed between the electrodes with gap spacing from 1 mm to 3 mm and with a dielectric barrier of thickness 1.5 mm while argon gas is fed at a controlled flow rate of 2liter per min. The electron temperature (Te) and electron density (ne) of the plasma have been determined by means of optical emission spectroscopy. Our results show that the electron density is of the order of 1016 cm−3 while the electron temperature is estimated to be ∼ 1 eV. The homogeneity and non-thermal nature of the discharge were utilized in the investigation of the change in wettabilty of a polymer sample subjected to the treatment by the discharge. Contact angle analysis showed that the discharge was effective in improving the wettability of low density Polyethylene (LDPE) polymer sample after the treatment

  6. An experimental study of atmospheric pressure dielectric barrier discharge (DBD) in argon

    Science.gov (United States)

    Subedi, D. P.; Tyata, R. B.; Shrestha, R.; Wong, C. S.

    2014-03-01

    In this paper, experimental results on atmospheric pressure argon dielectric barrier discharge (DBD) have been presented. The discharge was generated using a high voltage (0 to 20 kV) power supply operating at frequency of 10 to 30 kHz and was studied by means of electrical and optical measurements. A homogeneous and steady discharge was observed between the electrodes with gap spacing from 1 mm to 3 mm and with a dielectric barrier of thickness 1.5 mm while argon gas is fed at a controlled flow rate of 2liter per min. The electron temperature (Te) and electron density (ne) of the plasma have been determined by means of optical emission spectroscopy. Our results show that the electron density is of the order of 1016 cm-3 while the electron temperature is estimated to be ˜ 1 eV. The homogeneity and non-thermal nature of the discharge were utilized in the investigation of the change in wettabilty of a polymer sample subjected to the treatment by the discharge. Contact angle analysis showed that the discharge was effective in improving the wettability of low density Polyethylene (LDPE) polymer sample after the treatment.

  7. Phase resolved analysis of the homogeneity of a diffuse dielectric barrier discharge

    International Nuclear Information System (INIS)

    Cold atmospheric pressure plasmas have already proven their ability of supporting the healing process of chronic wounds. Especially simple configurations like a dielectric barrier discharge (DBD), comprising of one driven electrode which is coated with a dielectric layer, are of interest, because they are cost-effective and easy to handle. The homogeneity of such plasmas during treatment is necessary since the whole wound should be treated evenly. In this investigation phase resolved optical emission spectroscopy is used to investigate the homogeneity of a DBD. Electron densities and reduced electric field distributions are determined with temporal and spatial resolution and the differences for applied positive and negative voltage pulses are studied. (paper)

  8. Analysis of microdischarges in asymmetric dielectric barrier discharges in argon

    International Nuclear Information System (INIS)

    Theoretical and experimental studies of two different discharge modes in asymmetric dielectric barrier discharges in argon at atmospheric pressure have been performed. The first mode appears to be the well-known filamentary microdischarge with non-striated positive column whereas the second mode is characterized by discharge instabilities and the appearance of striations. Both experiment and model calculations predict a transition from the first mode to the second mode when the applied voltage amplitude is increased above approximately 2 kV. The reliability of the employed fluid model is confirmed by comparison of the current–voltage characteristics obtained by model calculations and measurements for different applied voltage amplitudes. The results of the model calculations point out that in the second discharge mode the ionization of excited argon atoms prevents the total recombination of charge carriers between two subsequent discharge events. This leads to the occurrence of the memory from one discharge to the following one, which plays an important role in mode transition. (paper)

  9. Dynamics of dielectric barrier discharges in different arrangements

    International Nuclear Information System (INIS)

    Based on experimental results, numerical investigations of dielectric barrier discharges (DBDs) have been performed in three basic configurations: in the volume, coplanar and surface discharge arrangements. It is shown that the DBD dynamics is the same in all arrangements and it is determined by the development of a few principal constituents, i.e. cathode- and anode-directed streamers, discharge channel, cathode layer and surface charges. It is found that the anode- and cathode-directed streamers appear with a highly conductive channel in between. The interaction of the streamers with conductive and dielectric surfaces determines the filamentary or homogeneous appearance of the discharge and its properties. The cathode-directed streamer is a self-sustaining phenomenon, which moves in a gas gap or along an electrode driven by a positive loop-back between photoemission and electron multiplication. The anode-directed streamer plays a subsidiary role. Depending on the kind of gas (electronegative or electropositive) and/or the degree of development of the cathode-directed streamer, the field strength in the conductive channels changes significantly. When the cathode-directed streamer touches the electrode surface, a cathode layer appears with parameters close to those of normal glow discharges. In volume discharge arrangements the movement of the streamers results in the appearance of Lichtenberg figures on dielectric surfaces. (paper)

  10. Dynamics of dielectric barrier discharges in coplanar arrangements

    International Nuclear Information System (INIS)

    The development of a discharge channel in coplanar dielectric barrier arrangements is investigated numerically. Its behaviour in oxygen, like the spatial and temporal distributions of the field strength, charged and neutral particles and energy density, is described in detail. It is found that the streamer development is mainly determined by photoemission. A cathode layer appears near the position where the cathode directed streamer touches the dielectric surface. Secondary electron emission by ion collisions becomes significant and the parameters of the cathode layer are near those of a normal glow discharge. The charge transfer and energy release happen in the conductive channel of the discharge, which appears on the dielectric surface as a result of the cathode streamer development. The field strength in the conductive channel is nearly constant and about 70-100 Td in oxygen and air

  11. Application of dielectric surface barrier discharge for food storage

    Directory of Open Access Journals (Sweden)

    Yassine BELLEBNA

    2015-12-01

    Full Text Available Ozone (O3 is a powerful oxidizer and has much higher disinfection potential than chlorine and other disinfectants. Ozone finds its application mainly in water treatment and air purification Dielectric barrier discharge (DBD method has proved to be the best method to produce ozone. Dried air or oxygen is forced to pass through a 1-2 mm gap. The aim of this study was to show that disinfection system using ozone generated by dielectric barrier discharge (DBD is an effective alternative to be used in food industry and ensures a safe quality of air for optimum preservation of fruits and vegetables. The DBDs are specific kind of discharges because one (or sometimes both electrodes is covered by a dielectric material, thereby preventing the discharge to move towards electrical breakdown. A succession of microdischarges occurs rapidly; their "lifetime" is in the range of a few nanoseconds. One of their most important applications is the production of ozone for air treatment, used mainly in the area of food industry, for extending the storage life of foods. After the achievement of a surface DBD reactor of cylindrical shape and its electrical characterization, it was then used as an ozone generator for air disinfection. Obtained results have shown that this reactor used as an ozone generator is effective for disinfection of air by removing viruses, bacteria and pathogens, causing the slowdown of the ripening process of fruits and vegetables.

  12. Plasma focus discharges with multiple current sheets

    International Nuclear Information System (INIS)

    Systematic measurements on the structure and the propagation velocity v(z, r) of the current sheets were carried out for deuterium plasma-focus discharges. Each discharge had a multiplicity N ≤ 4 (N = 2 in ∼80% of the discharges) of pinching current sheets. The linear correlation of coefficients between the total neutron yield per discharge, Y, and the velocity vi of the i-th sheet were determine for vi at different locations (z, r) -- z is the coordinate along the electrode axis orthogonal to r -- during the sheet rolling off the interelectrode gap (when dv/dz achieves its maximum value) and during the radial compression (maximum of dv/dr). Two quasi-identical plasma focus machines (with and without field distortion elements at the electrode breech) were utilized at variable levels of the capacitor bank energy W in the interval 13 kJ ≤ W ≤ 30 kJ, and peak electrode current IM (approx-gt 1 MA). The difference between the two systems was limited to a variation ΔC = 0.2 C and ΔL = 0.2 Lc of the capacitance C and inductance Lc of the of two-module capacitor bank in order to determine the derivatives ΔY/ΔL, ΔY/ΔW. The acquired information is applied to further increase Y (> 1010 neutrons per discharge from D + D reactions) for the assigned IM, W values. A neural network analysis is carried out to assess the bearing on Y -- and on the neutron pulse duration -- of the current-sheet mutual interference, specifically, of N and of the time-spacing between sheets

  13. Recent advances in the understanding of homogeneous dielectric barrier discharges

    Science.gov (United States)

    Massines, F.; Gherardi, N.; Naudé, N.; Ségur, P.

    2009-08-01

    This paper is a state of the art of the understanding on the physics of homogeneous dielectric barrier discharges at atmospheric pressure. It is based on the analysis of present and previous work about the behavior of these discharges and the conditions to get them. Mechanisms controlling the homogeneity during gas breakdown and discharge development are successively discussed. The breakdown has to be a Townsend one, the ionization has to be slow enough to avoid a large avalanche development. During the breakdown, the discharge homogeneity is related to the ratio of the secondary emission at the cathode (γ coefficient) on the ionization in the gas bulk (α coefficient). Higher is this ratio, higher is the pressure × gas gap product (Pd) value for which a Townsend breakdown is obtained. Among the phenomena enhancing the secondary emission there is the negative charge of the dielectric on the cathode surface, the trapping of ions in the gas and the existence of excited state having a long lifetime compared to the time between two consecutive discharges. The first phenomenon is always present when the electrodes are covered by a solid dielectric, the second one is related to the formation of a positive column and the third one is specific of the gas. During the discharge development, the homogeneity is mainly controlled by the voltage or the current imposed by the electrical circuit/electrode configuration and by the gas ability to be slowly ionized. Larger is the contribution of a multiple step ionization process like Penning ionization, higher will be the working domain of the discharge. A decrease of the gas voltage during the discharge development is a solution to enhance the contribution of this process. After 20 years of research a lot of mechanisms have been understood however there is still open questions like the nature of the Inhibited homogeneous DBD, surface energy transfers, role of attachment and detachment...

  14. An investigation of dielectric barrier discharge in Ar and Ar/NH3 mixture using cross-correlation spectroscopy

    OpenAIRE

    Kloc, P; Wagner, H-E; Trunec, D; Navrátil, Z; Fedoseev, G

    2010-01-01

    Abstract Dielectric barrier discharges (BDs) are known to operate in two distinctive modes. Filamentary mode of DB is characterized by large number of short lasting spatially bounded microdischarges. This type of discharge is typical for most cases of BDs at atmospheric pressure. Under some specific conditions another form of BD may arise. In this mode plasma covers uniformly the whole electrode area. This mode is usually referred to as diffuse or homogeneous mode of BD. This work presents...

  15. Thermoluminescence study of the trapped charge at an alumina surface electrode in different dielectric barrier discharge regimes

    OpenAIRE

    Ambrico, P F; Ambrico, M.; Colaianni, A; Schiavulli, L; Dilecce, G; S. De Benedictis

    2010-01-01

    Abstract 52.25.-b {Plasma properties} PACS 52.25.Mq {Dielectric properties} PACS 51.50.+v {Electrical properties} PACS 78.60.Kn {Thermoluminescence} PACS 72.20.Jv {Charge carriers: generation, recombination, lifetime, and trapping} Abstract. In the present study charge trapping effect in alumina dielectric surfaces has been deeply investigated by means of a dedicated dielectric barrier discharge apparatus under different discharge regime and gas mixtures. These work further validates our p...

  16. 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.

  17. Treatment of hazardous organic wastes using silent discharge plasmas

    International Nuclear Information System (INIS)

    During the past two decades, interest in applying non-equilibrium plasmas to the removal of hazardous chemicals from gaseous media has been growing, in particular from heightened concerns over the pollution of our environment and a growing body of environmental regulations. At the Los Alamos National Laboratory, we are currently engaged in a project to develop non-equilibrium plasma technology for hazardous waste treatment. Our present focus is on dielectric-barrier discharges, which are historically called silent electrical discharges. This type of plasma is also named a silent discharge plasma (SDP). We have chosen this method due to its potential for high energy efficiency, its scientific and technological maturity, and its scalability. The SDP process has been demonstrated to be reliable and economical for the industrial-scale synthesis of ozone, where municipal water treatment plants frequently require the on-site generation of thousands of kilograins per day (Eliasson ampersand Kogelschatz). The related methods of corona processing are presently the focus of work at other institutions, particularly for flue gas processing. Both SDP and corona processes are characterized by the production of large quantities of highly reactive free radicals, especially atomic oxygen O(3P) and the hydroxyl OH, in the gaseous medium and their subsequent reaction with contaminants. Our primary objective is to convert hazardous or toxic chemicals into non-hazardous compounds or into materials which are more amenable to treatment. In the ideal case, the hazardous wastes are destructively oxidized to simpler, non-hazardous compounds plus CO2 and H2O. Sometimes the reaction products are still potentially hazardous, but are easily treated by conventional methods to yield non-hazardous products

  18. Dielectric barrier discharge treatments for heparin immobilization on PVC films

    International Nuclear Information System (INIS)

    Low temperature plasmas represent a useful technique to modify the mechanical and physico-chemical characteristics of polymer surfaces. Among these techniques, the dielectric barrier discharge (DBD) can be used to initiate the functionalization, crosslinking, and/or chemical incorporation of various functional groups on these surfaces. In particular, this technique may be used to immobilize some biological active species interested in medical applications, for example the heparin. Thrombus formation on the implant is one of major processes at the blood/biomaterial interface and one of the solution to control the mechanism of the blood coagulation is to incorporate an anticoagulant element within the surface boundary layers of the implant. Heparin is an anticoagulant that can enhance the inactivation of clotting factors and, theoretically, it can be immobilized by ionic or covalent linkages on the polymeric surface. In this way, the hemocompatibility of the polymeric surfaces could increase, permitting to construct devices such as cardiopulmonary bypass circuits, hemodialyses, ventricular devices, etc., for what the thrombus formation and leukocyte activation is critical. Among the most common polymers used in medical applications, polyvinyl chloride (PVC) films are preferred, satisfying a wide range of safety performances and cost criteria. They are used to store substances e. g., blood and blood products drugs and injectables, membranes for gas adsorption etc. The physico-chemical and biological properties of PVC depend on the nature of the biological environment and of the amount of additives. In contact with the biological liquids and the blood, some elements from these are capable of extracting additives from PVC films and in very short time, the patient exposed to the implant might receive doses of plasticizers (for example) with the risk of possible toxic and biological effects due the transfer of these additives to the tissues. At the same time, depending on

  19. Pulsed corona and dielectric-barrier discharge processing of NO in N{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Penetrante, B.M.; Hsiao, M.C.; Merritt, B.T.; Vogtlin, G.E.; Wallman, P.H. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Neiger, M.; Wolf, O. [Lighting Technology Institute, University of Karlsruhe, D-76128 Karlsruhe (Germany); Hammer, T.; Broer, S. [Siemens Research Center, Plasma and Switching Technology, D-91050 Erlangen (Germany)

    1996-06-01

    Experimental results on pulsed corona and dielectric-barrier discharge processing of very dilute concentrations of NO in N{sub 2} are presented. These NO reduction experiments measure the {ital G} value for electron-impact dissociation of N{sub 2} and are used to infer the effective electron mean energy in an N{sub 2} discharge plasma at atmospheric pressure. The data have been obtained from three different laboratories using widely differing electrode structures, voltage wave forms, power measurements, and chemical analyses. The NO reduction yields from the discharge reactors tested are all similar, corresponding to an electron mean energy of 4.0{plus_minus}0.5 eV. {copyright} {ital 1996 American Institute of Physics.}

  20. Influence of dielectric barrier discharges on low Mach number shock waves at low to medium pressures

    International Nuclear Information System (INIS)

    For shock wave propagation in nonequilibrium plasmas, it has been shown that when the electron Debye length exceeds the shock wave discontinuity dimension, strong double layers are generated, propagating with the shock wave. Strong double layer formation leads to the enhancement of the local excitation, ionization, and local neutral gas heating which increases the shock wave velocity. It is shown that dielectric barrier discharges (DBD) in pure N2 also increase the shock wave velocity and broaden the shock wave. The DBD is considerably more energy efficient in producing these effects compared to a dc glow discharge and can operate over a wide pressure range. It is shown that these effects are also operative in the pure N2 discharge afterglow, allowing a wide range of pulse repetition frequencies

  1. Simulations of nanosecond-pulsed dielectric barrier discharges in atmospheric pressure air

    Energy Technology Data Exchange (ETDEWEB)

    Soo Bak, Moon; Cappelli, Mark A. [Mechanical Engineering Department, Stanford University, Stanford, California 94305 (United States)

    2013-03-21

    This paper describes simulations of nanosecond pulse plasma formation between planer electrodes covered by dielectric barriers in air at atmospheric pressure and 340 K. The plasma formation process starts as electrons detach from negative ions of molecular oxygen that are produced from the previous discharge pulse. An ionization front is found to form close to the positively biased electrode and then strengthens and propagates towards the grounded electrode with increasing gap voltage. Charge accumulation and secondary emission from the grounded electrode eventually lead to sheath collapse. One interesting feature is a predicted reversal in gap potential due to the accumulated charge, even when there is no reversal in applied potential. The simulation results are compared to recent measurement of mid-gap electric field under the same discharge conditions [Ito et al., Phys. Rev. Lett. 107, 065002 (2011)].

  2. The Key Factor for Uniform and Patterned Glow Dielectric Barrier Discharge

    International Nuclear Information System (INIS)

    We present the results from 2D fluid modeling of the key roles controlling the glow dielectric barrier discharge (DBD) structure. A uniform DBD can be sustained at lower frequency when the space charge reaches uniformity due to plasma decay, while the patterned structure appears above a critical frequency when the space charge is nonuniform. The patterns start from the electrode edge where the electric field is significantly distorted, characterized by the patterned seed electrons that always form ahead of the surface charges. The formation of the patterned DBD structure is associated with the lateral inhibition of the local increase of space charges. The distribution of the volume seed electrons plays a key role in the DBD structure while the distribution of surface charge is a result of the formed structure. (physics of gases, plasmas, and electric discharges)

  3. Main oxidation processes and their relative contributions in the NO removal by a dielectric barrier discharge for air cleaning

    International Nuclear Information System (INIS)

    The NO to NO2 removal in a dielectric barrier discharge plasma reactor is experimentally investigated in dry air at ambient temperature. A modelling approach aims to evaluate the relative importance of the main reactions into play, in coherence with the experimental results. (author)

  4. Formation of NOx from N2 and O2 in catalyst-pellet filled dielectric barrier discharges at atmospheric pressure.

    Science.gov (United States)

    Sun, Qi; Zhu, Aimin; Yang, Xuefeng; Niu, Jinhai; Xu, Yong

    2003-06-21

    At temperatures above 350 degrees C, significant amounts of NOx formed from N2 and O2 have been observed in Cu-ZSM-5 catalyst-pellet filled dielectric barrier discharges, indicating the necessity of using low-temperature performance in all plasma-catalytic processes for removal of air pollutants. PMID:12841270

  5. Dynamics of dielectric barrier discharge in non-uniform gas composition investigated by laser spectroscopic measurements

    Science.gov (United States)

    Urabe, Keiichiro; Ito, Yosuke; Choi, Joon-Young; Sakai, Osamu; Tachibana, Kunihide

    2009-10-01

    It is well known that stable and glow dielectric barrier discharge (DBD) at atmospheric pressure is observed using helium gas and AC high voltage of kHz-order frequency. We have investigated the discharge mechanisms of DBDs from a view point of the spatiotemporal distributions of excited species measured by laser spectroscopic methods. In this presentation, we will show convincing arguments about the discharge model of the DBD especially having the non-uniformity of gas composition. As a DBD plasma source for atmospheric pressure processes, we have investigated an atmospheric pressure plasma jet (APPJ) using helium gas flow in ambient air, and this plasma source can be regarded as the DBD near the boundary interface of helium gas and ambient air. In this APPJ, we observed spatiotemporal distributions of excited species density inside the helium gas channel, using laser absorption spectroscopy and laser induced fluorescence, to measure the densities of helium metastable atom (2^3S1 state) and nitrogen ion (X^2σg^+ state) respectively. To study the influence of nitrogen gas contamination on the discharge profile of DBD, we have also applied CO2-laser heterodyne interferometry to measure the special distribution of electron density in parallel-plate DBD.

  6. Uniformity of dielectric barrier discharges using mesh electrodes

    International Nuclear Information System (INIS)

    In this paper, the uniformities of dielectric barrier discharges (DBDs) produced by different mesh electrodes are studied. If the aperture of the mesh electrode is long enough, the discharge spots are periodic. If the aperture is smaller than 0.5 mm, the discharge spots will be distributed randomly and even more densely than when produced by a planar electrode. Because the evaluation of the uniformity of the DBD, which consists of a large number of microdischarges, is different from that of a glow DBD or a Townsend DBD, the coefficient of variation (CV) of the gray level distribution of the discharge light emission is used to describe the uniformity of the DBD. The smaller the value of CV, the more uniform is the discharge. The experimental results show that the uniformity of the DBD produced by some mesh electrodes is even better than that by a planar electrode if the aperture of the mesh electrode is small enough. On the other hand, a new dimensionless scale invariant (h), which includes the combined effect of the aperture and the normalized change rate of the field strength of the avalanche head, is presented to analyze the physical mechanisms leading to a relatively uniform DBD according to the condition of the slow development of many avalanches at a low electric field. The calculated results show that the variation trend of h for different mesh electrodes is almost the same as that of the CV. This means that the dimensionless scale invariant h can be used to study the discharge uniformity. (paper)

  7. Dielectric Barrier Discharge Characteristics of Multineedle-to-Cylinder Configuration

    Directory of Open Access Journals (Sweden)

    Caixin Sun

    2011-12-01

    Full Text Available A dielectric barrier discharge (DBD produces a homogenous discharge with low energy consumption, offering broad developmental prospects, and this discharge process is also the mechanism through which charges are transported. Higher reaction efficiency is achieved when more charges are transported. Focusing on the electrode configuration of the multineedle-to-cylinder (MC system, i.e., the structure of needles arrayed on the inner coaxial rod, the effect of needle arrangement, including needle length (NL, inter axial needle distance (ID, and inter axial needle rotation angle (INRA, on the transported charge per cycle and discharge power in DBDs is investigated. The finite-element method (FEM and quasi-static field simulation are adopted to study the active region (AR where the electric field strength exceeds the breakdown electric field strength between MC electrodes because this region plays a dominant role in DBD. The improvement of its volume ratio in the reactor allows an increase in discharge power. The simulation results are in accordance with the experimental results, which illustrate that quasi-static field simulation is effective and reliable. Simulation results show that mutual effects of nearby needles and between needles and the inner rod exist. As a result, shorter ID (1.5 mm, needles with similar lengths (3.5 mm are arranged, and an INRA of 0° is proven to be the optimal structure because it produces the highest AR volume ratio. The result is experimentally validated by transported charges per cycle and discharge power obtained through Lissajous figures.

  8. Uniformity of dielectric barrier discharges using mesh electrodes

    Science.gov (United States)

    Ye, Qizheng; Wu, Yunfei; Li, Xingwang; Chen, Tian; Shao, Guiwei

    2012-12-01

    In this paper, the uniformities of dielectric barrier discharges (DBDs) produced by different mesh electrodes are studied. If the aperture of the mesh electrode is long enough, the discharge spots are periodic. If the aperture is smaller than 0.5 mm, the discharge spots will be distributed randomly and even more densely than when produced by a planar electrode. Because the evaluation of the uniformity of the DBD, which consists of a large number of microdischarges, is different from that of a glow DBD or a Townsend DBD, the coefficient of variation (CV) of the gray level distribution of the discharge light emission is used to describe the uniformity of the DBD. The smaller the value of CV, the more uniform is the discharge. The experimental results show that the uniformity of the DBD produced by some mesh electrodes is even better than that by a planar electrode if the aperture of the mesh electrode is small enough. On the other hand, a new dimensionless scale invariant (h), which includes the combined effect of the aperture and the normalized change rate of the field strength of the avalanche head, is presented to analyze the physical mechanisms leading to a relatively uniform DBD according to the condition of the slow development of many avalanches at a low electric field. The calculated results show that the variation trend of h for different mesh electrodes is almost the same as that of the CV. This means that the dimensionless scale invariant h can be used to study the discharge uniformity.

  9. Packaging barrier films deposited on PET by PECVD using a new high density plasma source

    International Nuclear Information System (INIS)

    Barrier films for packaging applications are deposited by plasma enhanced chemical vapor deposition (PECVD) on PET film using a new, high density plasma source. The new source, termed the Penning Discharge Plasma source, implements a novel magnetic field/electrode configuration that confines the electron Hall current in an endless loop adjacent to the substrate. By confining the Hall current, a dense, uniform plasma is created and sustained over wide substrates. The result is high rate deposition at low substrate temperatures. The water vapor permeation of SiO2 barrier films is reported as well as deposition rate, coating thickness and other film properties

  10. Surface dielectric barrier discharges exhibiting field emission at high pressures

    International Nuclear Information System (INIS)

    Surface dielectric barrier discharges (DBDs) are investigated experimentally in CO2 from atmospheric pressure up to supercritical conditions. Two discharge regimes are generated using 10 kHz ac excitation. The ‘standard’ regime is similar to previously studied surface DBDs in terms of onset voltage as a function of pressure, as well as electrical and optical emission characteristics. However, a ‘field-emitting’ regime emerges starting from 0.7 MPa that exhibits constant onset voltage up to 7.9 MPa, purely continuum emission spectra in the visible/near-infrared range and current waveforms similar to an atmospheric-pressure Townsend discharge with ionization instabilities. The maximum amount of negative charge deposited as a function of the applied voltage amplitude is consistent with the Fowler–Nordheim equation, which demonstrates the presence of field emission. Furthermore, this behavior cannot be attributed to the Townsend or streamer ionization mechanisms, secondary electron emission or non-discharge processes. No field-emitting structures are specially added to the electrodes. The onset voltage of the field-emitting regime does not follow the modified Paschen's law for field emission-assisted breakdown. (paper)

  11. Surface charge measurements in barrier discharges on different time scales

    Science.gov (United States)

    Wild, Robert; Volkhausen, Christian; Benduhn, Johannes; Stollenwerk, Lars

    2015-09-01

    The deposition of surface charge in barrier discharges is a process that influences the ongoing discharge significantly. This contribution presents the measurement of absolute surface charge densities and their dynamics in a laterally extended setup. An electro-optic BSO crystal is used as dielectric. The absolute charge density on its surface is deduced from the change of polarisation of light passing the crystal. Using different temporal resolutions, the behavior of charge is investigated on three different time scales. The highest temporal resolution of the technique is in the order of hundreds of nanoseconds. Therefore it is possible for the first time to observe the charge deposition process during an active discharge. On the time scale of the applied voltage period (several microseconds), the conservation mechanisms of a lateral discharge pattern is investigated. For this, the influence of surface charge and metastable species in the volume is estimated. Further, the behavior of the surface charge spots on a variation of the external voltage and gas pressure is studied. Measurements on a time scale in the magnitude of seconds reveal charge decay and transport phenomena. This work was funded by the Deutsche Forschungsgemeinschaft.

  12. The effect of electrode tilt angle on the characteristics of coplanar dielectric barrier discharges with Xe-Ne mixtures

    Science.gov (United States)

    Shim, Seung Bo; Song, In Cheol; Lee, Ho-Jun; Lee, Hae June

    2011-07-01

    The results of a two-dimensional fluid simulation of a plasma display panel (PDP) cell show that the discharge characteristics of a coplanar dielectric barrier discharge can be controlled by the electrode tilt angle rather than by the gas mixture ratio or gap distance. The change in the tilt angle results in a significant change in the wall charge distribution and the discharge duration for each pulse. Therefore, the breakdown voltage, plasma density, light brightness, and luminous efficacy can be controlled by the tilt angle. A concave electrode structure allows large wall charge accumulation near the outer edge of two coplanar electrodes, and it results in a long-duration discharge, high luminance, and high luminous efficacy. On the other hand, a convex electrode structure allows high wall charge accumulation near the gap between two coplanar electrodes, and it results in a short-duration discharge with a decreased breakdown voltage.

  13. [OH(X)] measurements by resonant absorption spectroscopy in a high pulse voltage triggered Dielectric Barrier Discharge.

    OpenAIRE

    Hibert, C.; Gaurand, I.; Motret, O; Pouvesle, J.M.

    1999-01-01

    Good understanding of the different phases of involved plasma-chemistry is essential for the development of non thermal plasma technologies for pollution control. These techniques are often based on the production of radicals from dissociation parent gases that, in turn, decompose the toxic compounds. Our research concerns OH radical production in a high pulse voltage triggered dielectric barrier discharge (DBD). OH (A2+ - X2 (0,0)) emission in argon-water vapor gas mixtures has been studi...

  14. Electrical Characteristics of Dielectric-Barrier Discharges in Atmospheric Pressure Air Using a Power-Frequency Voltage Source

    International Nuclear Information System (INIS)

    Dielectric-barrier discharges (DBDs) in atmospheric pressure air have been studied by using a power-frequency voltage source. In this paper the electrical characteristics of DBDs using glass and alumina dielectrics have been investigated experimentally. According to the Lissajous figures of voltage-charges, it is discovered that the discharge power for an alumina dielectric is much higher than that for a glass dielectric at the same applied voltage. Also, the voltage-current curves of the glass and alumina dielectrics confirm the fact that the dielectric barriers behave like semiconducting materials at certain applied voltages. (low temperature plasma)

  15. 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.

  16. Determination of Ionization Coefficient of Atmospheric Helium in Dielectric Barrier Discharge

    International Nuclear Information System (INIS)

    A weakly luminous layer close to the anode is observed at time far ahead of the current pulse in dielectric barrier discharge of helium at atmospheric pressure and it is considered as the result of a very weak Townsend discharge. Based on the assumption that the space charge produced by this Townsend discharge is too small to distort the uniform electric field in the gas gap, the electrons have more or less the same energy over the entire gap and the spatial distribution of the discharge light is proportional to the distribution of electron density. This light distribution is obtained by processing side-view photograph of discharge gap using an intensified charge coupled device camera with an exposure time of 20 ns. By fitting a theoretically derived formula with the measured curve of light distribution, the Townsend electron ionization coefficient a is determined to be 31 cm−1 at E/p = 3.6 V·cm−1·Torr−1, which is much higher than that obtained by solving the Boltzmann equation of pure helium. It is believed that penning ionization of helium metastables with impurity of nitrogen molecules makes great contribution to the experimentally determined α value. The contribution of this penning ionization to α is roughly estimated. (physics of gases, plasmas, and electric discharges)

  17. Investigation of nanosecond pulsed dielectric barrier discharge using plate-to-plate electrode with asymmetric dielectric arrangement in airflow

    Science.gov (United States)

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

    2016-05-01

    Atmospheric pressure dielectric barrier discharge plasma is produced in airflow by applying nanosecond high voltage pulses with peak voltage about 35 kV and rising time about 40 ns on a plate-to-plate electrode arrangement. The effects of airflow rate (0-50 m/s) on the discharge characteristics are investigated under different barrier conditions (the bare anode case and the bare cathode case). For both cases, the breakdown voltage and the time lag increase distinctly and the discharge intensity decreases sharply when the airflow rate increases from 0 to 30 m/s, and then keep almost constant until the airflow rate is further increased to 50 m/s. For the bare anode case (the cathode is covered by dielectric plate), the discharge mode transforms gradually from filamentary to diffuse discharge with the increasing airflow rate. While for the bare cathode case, some micro-discharge channels are still excited, though the discharge becomes more diffuse when the airflow rate is higher than 30 m/s. By acquiring the time-resolved images of the discharge, it is proved that it is the primary discharge which becomes diffuse when airflow is introduced and the following two discharges of the same voltage pulse occur principally at the positions where the primary discharge is more intense. And in both cases, the plasma temperatures are reduced, but the degree is different. All the phenomena can be explained mainly by the variation of the space charge distribution when the airflow is introduced into the discharge gap. And it is indicated that the bare anode case has an advantage in obtaining diffuse discharge.

  18. CO2 reforming of methane: valorizing CO2 by means of Dielectric Barrier Discharge

    International Nuclear Information System (INIS)

    The impact of pollution on the environment is causing several problems that are to be reduced as much as possible. One important example is the production of CO2 that is emitted by many transport and industrial applications. An interesting solution is to view CO2 as a source instead of a product that can be stocked. The case considered in this work is the CO2 reformation of methane producing hydrogen and CO. It is an endothermic reaction, for which the activition barrier needs to be overcome. The method of Dielectric Barrier Discharge can do this efficiently. The process relies on the collision of electrons, which are accelerated under an electrical field that is created in the discharge area. This leads to the formation of reactive species, which facilitate the abovementioned reaction. The determination of the electron density is performed by PLASIMO. The study is subsequently continued using the Reaction Engineering module in COMSOL (with an incorporated kinetic mechanism) in order to model the discharge phase. Then COMSOL (continuity and Navier-Stokes equations) is used to model the flow in the post-discharge phase. The results showed that both a 2D and 3D model can be used to model the chemical-plasma process. These methods need strongly reduced kinetic mechanism, which in some cases can cause loss of precision. It is also observed that the present experimental set-up that is modeled needs to be improved. A suggestion is made.

  19. [Measurement of active particles generated in a coaxial barrier discharge by spectral method].

    Science.gov (United States)

    Li, Xue-Chen; Chang, Yuan-Yuan; Jia, Peng-Ying

    2013-05-01

    Coaxial dielectric barrier discharge has extensive application prospects. A dielectric barrier discharge device with water electrode was used to investigate the discharge properties and spectral intensity emitted from active particles in the air by optical method. Results indicate that the optical emission spectra consist of spectral lines from oxygen atoms (777.5 and 844.6 nm), which implies that oxygen atoms with high chemical activity were generated in the discharge plasma. Through spatially resolved measurements, spectral intensities from oxygen atoms were given as functions of the experimental parameters such as the value of the applied voltage, the gas flow rate and argon content. Results show that the spectral line intensity from oxygen atom increases with increasing the peak value of the applied voltage, increases with increasing the gas flow rate, reaches its maximum with a gas flow rate of 30 L x min(-1) and then decreases with further increasing the gas flow rate. Similarly, the spectral line intensity increases firstly and then decreases with increasing argon content (in a mixture of argon and air) and a maximum is reached when argon content is 16.7%. PMID:23905311

  20. Partial oxidation of methane in a temperature-controlled dielectric barrier discharge reactor

    KAUST Repository

    Zhang, Xuming

    2015-01-01

    We studied the relative importance of the reduced field intensity and the background reaction temperature in the partial oxidation of methane in a temperature-controlled dielectric barrier discharge reactor. We obtained important mechanistic insight from studying high-temperature and low-pressure conditions with similar reduced field intensities. In the tested range of background temperatures (297 < T < 773 K), we found that the conversion of methane and oxygen depended on both the electron-induced chemistry and the thermo-chemistry, whereas the chemical pathways to the products were overall controlled by the thermo-chemistry at a given temperature. We also found that the thermo-chemistry enhanced the plasma-assisted partial oxidation process. Our findings expand our understanding of the plasma-assisted partial oxidation process and may be helpful in the design of cost-effective plasma reformers. © 2014 The Combustion Institute.

  1. Isotope labelling to study molecular fragmentation during the dielectric barrier discharge wet reforming of methane

    Science.gov (United States)

    Montoro-Damas, Antonio M.; Gómez-Ramírez, Ana; Gonzalez-Elipe, Agustín R.; Cotrino, José

    2016-09-01

    Isotope labelling is used to study the wet plasma reforming of methane in a dielectric barrier discharge reactor using D2O and CH4 as reactants. Besides the formation of CO and hydrogen as main products, different partitions of H and D atoms are found in the hydrogen (i.e., H2, HD, D2), methane (i.e., CH4, CH3D and CH2D2) and water (D2O, DHO) molecules detected by mass spectrometry as outlet gases of the plasma process. The effect of operating parameters such as applied current, residence time and the addition of oxygen to the reaction mixture is correlated with the H/D distribution in these molecules, the overall reaction yield and the energetic efficiency of the process. The results prove the plasma formation of intermediate excited species that rendering water and methane instead of CO and hydrogen greatly contribute to decrease the overall energy efficiency of the reforming process.

  2. 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

  3. Decolorization of reactive black 5 using dielectric barrier discharge in the presence of inorganic salts

    OpenAIRE

    Dojčinović Biljana P.; Roglić Goran M.; Obradović Bratislav M.; Kuraica Milorad M.; Tosti Tomislav B.; Marković Marijana D.; Manojlović Dragan D.

    2012-01-01

    Inorganic salts improve the coloration of textiles, which increase pollution load on dyehouse effluent in general. Decolorization of reactive textile dye C.I. Reactive Black 5 was studied using Advanced Oxidation Processes (AOPs) in a non-thermal plasma reactor, based on coaxial water falling film Dielectric Barrier Discharge (DBD). Initial dye concentration in the solution was 40.0 mg L-1. The effects of addition of inorganic salt different high concentrations (NaCl, Na2SO4 and Na2CO3)...

  4. Modeling and comparison of sinusoidal and nanosecond pulsed surface dielectric barrier discharges for flow control

    International Nuclear Information System (INIS)

    Surface dielectric barrier discharges have been proposed as means of airflow actuation. A simplified air plasma model fully coupled with gas dynamics is presented and solved numerically using asynchronous mesh adaptation and time integration. Two modes of actuation depending on the driving voltage waveform are presented and analyzed. The first one uses high-voltage sine waveform in the kilohertz frequency range to transfer momentum from ions to gas molecules. The second one uses high-voltage nanosecond pulses to transfer energy to the neutral gas on a short time scale thus generating shockwaves.

  5. Modeling and comparison of sinusoidal and nanosecond pulsed surface dielectric barrier discharges for flow control

    Energy Technology Data Exchange (ETDEWEB)

    Unfer, T; Boeuf, J-P, E-mail: unfer@laplace.univ-tlse.f [Universite de Toulouse, UPS, INPT, LAPLACE, Toulouse (France)

    2010-12-15

    Surface dielectric barrier discharges have been proposed as means of airflow actuation. A simplified air plasma model fully coupled with gas dynamics is presented and solved numerically using asynchronous mesh adaptation and time integration. Two modes of actuation depending on the driving voltage waveform are presented and analyzed. The first one uses high-voltage sine waveform in the kilohertz frequency range to transfer momentum from ions to gas molecules. The second one uses high-voltage nanosecond pulses to transfer energy to the neutral gas on a short time scale thus generating shockwaves.

  6. SO{sub 2} removal from air with dielectric barrier discharges

    Energy Technology Data Exchange (ETDEWEB)

    Saveliev, A B; Pietsch, G J; Murtazin, A R; Fried, A [RWTH Aachen University, Electrical Engineering and Gas Discharge Technology, Schinkelstr. 2, 52056 Aachen (Germany)

    2007-08-15

    Dielectric barrier discharges are sources of non-thermal plasmas, in which chemical active particles are generated effectively. One of the most promising applications is chemical processing of gaseous substances, e.g. synthesis or decomposition. The removal of air pollutants such as sulfur dioxide from dry and humid air at atmospheric pressure is investigated experimentally as well as theoretically. The role of chemically active particles, especially of atomic oxygen and of OH radicals, is shown. Optimal conditions of the removal process are determined.

  7. Electron-induced dry reforming of methane in a temperature-controlled dielectric barrier discharge reactor

    KAUST Repository

    Zhang, Xuming

    2013-09-23

    Dry reforming of methane has the potential to reduce the greenhouse gases methane and carbon dioxide and to generate hydrogen-rich syngas. In reforming methane, plasma-assisted reforming processes may have advantages over catalytic processes because they are free from coking and their response time for mobile applications is quick. Although plasma-assisted reforming techniques have seen recent developments, systematic studies that clarify the roles that electron-induced chemistry and thermo-chemistry play are needed for a full understanding of the mechanisms of plasma-assisted reformation. Here, we developed a temperature-controlled coaxial dielectric barrier discharge (DBD) apparatus to investigate the relative importance of electron-induced chemistry and thermo-chemistry in dry reforming of methane. In the tested background temperature range 297-773 K, electron-induced chemistry, as characterized by the physical properties of micro-discharges, was found to govern the conversions of CH4 and CO2, while thermo-chemistry influenced the product selectivities because they were found to depend on the background temperature. Comparisons with results from arc-jet reformation indicated that thermo-chemistry is an efficient conversion method. Our findings may improve designs of plasma-assisted reformers by using relatively hotter plasma sources. However, detailed chemical kinetic studies are needed. © 2013 IOP Publishing Ltd.

  8. Gas temperature effects in micrometre-scale dielectric barrier discharges

    Energy Technology Data Exchange (ETDEWEB)

    Sitaraman, H; Raja, L L, E-mail: lraja@mail.utexas.edu [Department of Aerospace Engineering and Engineering Mechanics, University of Texas at Austin, TX 78712 (United States)

    2011-07-06

    A numerical modelling study of micrometre-length-scale (gap distances of {approx}50-100 {mu}m) dielectric barrier discharges (micro-DBDs) is reported. A comparison of micro-DBDs with classical large-scale DBDs (gap distances of {approx} mm) reveals the principal effect of downscaling DBD gap dimensions on the gas heating in these discharges. A one-dimensional, self-consistent, multi-species, multi-temperature continuum model is used in the simulations. For a constant pd (pressure x discharge gap distance) and applied voltage waveform (500 V, 10 MHz), a larger cycle-averaged gas temperature rise is seen in the micro-DBDs {approx}hundreds of kelvin compared with much smaller rise {approx}tens of kelvin in the classic DBDs. The gas temperature increase in micro-DBDs is mainly due to the rapid increase in the power densities as the gap dimensions are decreased compared with the increase in the wall loss with decreasing gap distances. For conditions studied in this work, the power densities in micro-DBDs are about four orders of magnitude larger than classic DBDs. Operation at higher frequencies, with other conditions remaining constant, is observed to favour larger gas temperatures in micro-DBDs. Micro-DBDs are therefore excellent device candidates to provide controllable gas heating in a variety of micro-electro mechanical systems; small spacecraft electrothermal micropropulsion devices being an example.

  9. Gas temperature effects in micrometre-scale dielectric barrier discharges

    International Nuclear Information System (INIS)

    A numerical modelling study of micrometre-length-scale (gap distances of ∼50-100 μm) dielectric barrier discharges (micro-DBDs) is reported. A comparison of micro-DBDs with classical large-scale DBDs (gap distances of ∼ mm) reveals the principal effect of downscaling DBD gap dimensions on the gas heating in these discharges. A one-dimensional, self-consistent, multi-species, multi-temperature continuum model is used in the simulations. For a constant pd (pressure x discharge gap distance) and applied voltage waveform (500 V, 10 MHz), a larger cycle-averaged gas temperature rise is seen in the micro-DBDs ∼hundreds of kelvin compared with much smaller rise ∼tens of kelvin in the classic DBDs. The gas temperature increase in micro-DBDs is mainly due to the rapid increase in the power densities as the gap dimensions are decreased compared with the increase in the wall loss with decreasing gap distances. For conditions studied in this work, the power densities in micro-DBDs are about four orders of magnitude larger than classic DBDs. Operation at higher frequencies, with other conditions remaining constant, is observed to favour larger gas temperatures in micro-DBDs. Micro-DBDs are therefore excellent device candidates to provide controllable gas heating in a variety of micro-electro mechanical systems; small spacecraft electrothermal micropropulsion devices being an example.

  10. Treatment of Wastewater by Ozone Produced in Dielectric Barrier Discharge

    Directory of Open Access Journals (Sweden)

    Rita Bhatta

    2015-01-01

    Full Text Available There is rapid diminishing of water resources in many countries due to, for example, population growth and constant reduction in fresh water supply. The sewage wastewater, industrial effluents, and municipal wastewater are directly and indiscriminately discharged into rivers and lakes and thus primarily cause water pollution in Nepal. This has increased the water crisis and also causes environmental deterioration. Therefore, the need for the development of an effective, cheap, and environmentally friendly process for the treatment of wastewater before discharging into aquatic environment has emerged. Treatment by ozone produced from dielectric barrier discharge is one of the emerging technologies for such application. The ozonation process is more effective for disinfection and degradation of organic pollutants from water. The current study describes the treatment of wastewater of selected site within Kathmandu. Results on various physicochemical and microbial parameters of the inlet and outlet samples are discussed. Our results showed slight increase in pH, decrease in chemical oxygen demand, and significant increase in dissolved oxygen after ozonation. Importantly, ozonation caused total reduction of fecal coliform.

  11. Evaluation of Dielectric-Barrier-Discharge Actuator Substrate Materials

    Science.gov (United States)

    Wilkinson, Stephen P.; Siochi, Emilie J.; Sauti, Godfrey; Xu, Tian-Bing; Meador, Mary Ann; Guo, Haiquan

    2014-01-01

    A key, enabling element of a dielectric barrier discharge (DBD) actuator is the dielectric substrate material. While various investigators have studied the performance of different homogeneous materials, most often in the context of related DBD experiments, fundamental studies focused solely on the dielectric materials have received less attention. The purpose of this study was to conduct an experimental assessment of the body-force-generating performance of a wide range of dielectric materials in search of opportunities to improve DBD actuator performance. Materials studied included commonly available plastics and glasses as well as a custom-fabricated polyimide aerogel. Diagnostics included static induced thrust, electrical circuit parameters for 2D surface discharges and 1D volume discharges, and dielectric material properties. Lumped-parameter circuit simulations for the 1D case were conducted showing good correspondence to experimental data provided that stray capacitances are included. The effect of atmospheric humidity on DBD performance was studied showing a large influence on thrust. The main conclusion is that for homogeneous, dielectric materials at forcing voltages less than that required for streamer formation, the material chemical composition appears to have no effect on body force generation when actuator impedance is properly accounted for.

  12. Large-scale surface dielectric barrier discharge type reactor : effect of the electric wind on the conversion effectiveness

    Energy Technology Data Exchange (ETDEWEB)

    Jolibois, J. [Univ. de Poitiers, Poitiers (France). Centre national de la recherche scientifique, Laboratoire de Catalyse en Chimie Organique; Poitiers Univ., Futuroscope Chasseneuil Cedex (France). Centre national de la recherche scientifique, Inst. Pprime; Zouzou, N.; Moreau, E. [Poitiers Univ., Futuroscope Chasseneuil Cedex (France). Centre national de la recherche scientifique, Inst. Pprime; Tatibouet, J.M. [Univ. de Poitiers, Poitiers (France). Centre national de la recherche scientifique, Laboratoire de Catalyse en Chimie Organique

    2010-07-01

    Non-thermal plasma (NTP) techniques offer an innovative approach for air pollution reduction. Most studies in NTP techniques use volumetric discharge reactors with small dimensions and low flow rates at laboratory scale. The objective of this study was to develop an air pollution control plasma reactor at industrial scale with surface discharge. Propene (C{sub 3}H{sub 6}) was oxidized at high flow rates in a large-scale plasma reactor based on surface dielectric barrier discharge (DBD). Three different configurations of surface discharges were tested with 15 ppm of C{sub 3}H{sub 6} in air at ambient temperature for a flow rate of 50 m{sup 3} per hour. The properties of these different surface discharges were analyzed using chemical measurements and 3 component particle image velocimetry (PIV) measurements. PIV measurements were used characterize the effect of the electric wind on the polluted gas airflow inside the reactor and to explain the differences of effectiveness of the three tested plasma generators. For the three plasma generators, a propene oxidation of up to 45 percent was obtained at one J per liter. The electric wind produced by the surface discharge resulted in the formation of vortices inside the plasma reactor. This electric wind can increase gas mixing inside the plasma reactor and therefore plays a key role in conversion efficiency. It was concluded that the electric wind produced by surface discharges enables the use of this type of discharge for VOC elimination at high flow rate, with the same effectiveness of volumetric discharges. 5 refs., 10 figs.

  13. Deactivation of Streptococcus mutans Biofilms on a Tooth Surface Using He Dielectric Barrier Discharge at Atmospheric Pressure

    Science.gov (United States)

    Imola, Molnar; Judit, Papp; Alpar, Simon; Sorin, Dan Anghel

    2013-06-01

    This paper presents a study of the effect of the low temperature atmospheric helium dielectric barrier discharge (DBD) on the Streptococcus mutans biofilms formed on tooth surface. Pig jaws were also treated by plasma to detect if there is any harmful effect on the gingiva. The plasma was characterized by using optical emission spectroscopy. Experimental data indicated that the discharge is very effective in deactivating Streptococcus mutans biofilms. It can destroy them with an average decimal reduction time (D-time) of 19 s and about 98% of them were killed after a treatment time of 30 s. According to the survival curve kinetic an overall 32 s treatment time would be necessary to perform a complete sterilization. The experimental results presented in this study indicated that the helium dielectric barrier discharge, in plan-parallel electrode configuration, could be a very effective tool for deactivation of oral bacteria and might be a promising technique in various dental clinical applications.

  14. Surface modification of materials by dielectric barrier discharge deposition of fluorocarbon films

    Energy Technology Data Exchange (ETDEWEB)

    Liu Dongping, E-mail: Dongping.liu@dlnu.edu.c [School of Science, Dalian Nationalities University, Dalian 116600 (China); Yin Yejun [School of Science, Dalian Nationalities University, Dalian 116600 (China); School of Mechanical Engineering, Dalian Jiaotong University, Dalian 116021 (China); Li Dongming [School of Mechanical Engineering, Dalian Jiaotong University, Dalian 116021 (China); Niu Jinhai; Feng Zhixing [School of Science, Dalian Nationalities University, Dalian 116600 (China)

    2009-05-01

    Dielectric barrier discharges have been used to deposit fluorocarbon (FC) films on various materials, such as paper, glass, and silicon substrates. The primary monomers used for plasma polymerization were difluoromethane (CH{sub 2}F{sub 2}), octafluoropropane (C{sub 3}F{sub 8}), and octafluorocyclobutane (C{sub 4}F{sub 8}). FC films were characterized using Fourier transform infrared spectroscopy, atomic force microscopy, static contact angle measurements, and scanning electron microscopy. Surface and structural properties of deposited films are strongly dependent on the plasma compositions and plasma parameters. FC films deposited on paper are to enhance its barrier properties and to achieve hydrophobic surfaces. Contact angle studies reveal that a minimum FC film thickness of about 200 nm on paper is required to completely cover surface and near-surface fibers, thereby providing the paper with long term hydrophobic character. In the C{sub 3}F{sub 8} and C{sub 4}F{sub 8} systems, the contact angles of the deposited films do not change appreciably with plasma parameters and are strongly dependent on the substrate roughness. Hydrogenated FC films deposited with CH{sub 2}F{sub 2} plasmas show the relatively low contact angles due to the existence of CH{sub X} (x = 1-3) groups.

  15. Characteristics of powdered activated carbon treated with dielectric barrier discharge for electric double-layer capacitors

    International Nuclear Information System (INIS)

    Highlights: ► The specific capacitance of the EDLCs could be improved by oxygen plasma treatment. ► 15 s treated EDLCs showed a 20% increase in capacitance relative to untreated EDLCs. ► The plasma treatment yields EDLCs that are suitable for high-energy applications. - Abstract: The electrochemical properties of electric double-layer capacitors (EDLCs) made with plasma-treated powdered activated carbon (treated using a dielectric barrier discharge) were examined using cyclic voltammetry (CV), Cole–Cole plots, and X-ray photoelectron spectroscopy (XPS). The dielectric barrier discharge method, which operates at atmospheric pressure, dramatically reduces the processing time and does not require vacuum equipment, making it a more practical alternative than low-pressure plasma treatment. The experimental data indicate that the specific capacitance of the EDLCs could be improved by oxygen plasma treatment. Capacitance of EDLCs made with activated carbon treated for 15 s showed 193.5 F/g that 20% increase in the specific capacitance relative to untreated EDLCs. This result indicates that the plasma treatment yields EDLCs that are suitable for high-energy applications. The enhancement of capacitance was mainly attributed to an increase in the BET surface area of the activated carbon and the creation of carboxyl groups on the surface of the carbon. The carboxyl groups induced oxidation–reduction reactions in the presence of O2 which was included in the operation gas. In addition, the carboxyl groups improved the penetration of the electrolyte solution into the carbon electrodes.

  16. Eddy current calculation of plasma discharge in EAST

    International Nuclear Information System (INIS)

    During Tokamak plasma discharge, induced eddy currents in the vacuum vessel by PF coils and plasma have an important influence on plasma discharge. Currents are induced in PF coil and plasma by induced eddy currents in the vacuum vessel in return. In order to realize the feedback control of plasma discharge, it is necessary to calculate the induced eddy current distribution in the vacuum vessel. In this paper, by using the high speed CCD and image processing, and dividing the vacuum vessel into 40 elements, eddy current distribution was calculated with least squares algorithm, which is proved to being a desirable result. (authors)

  17. Electrical Characteristics of Pulsed Corona Discharge Plasmas in Chitosan Solution

    International Nuclear Information System (INIS)

    Pulsed discharge plasma has exhibited active potential to prepare low molecular weight chitosan. In the present study, the viscosity of chitosan solution was decreased noticeably after treated with pulsed corona discharge plasma. An experimental investigation on electrical characteristics of pulsed corona discharge plasma in chitosan solution was conducted with a view toward getting insight into discharge process. Factors affecting I–V curve, single pulse injection energy and pulse width were studied. Experimental results showed positive effect of pulsed peak voltage on discharge plasma in chitosan solution. Pulse-forming capacitor greatly influenced the discharge form, and 4 nF was observed as a suitable value for efficiently generating stable discharge plasmas. As the electrode distance was larger than 10 mm, it had slight impact on discharge plasma due to the excellent conductive-property of chitosan solution. The injection energy significantly increased with air flow rate, while the pulse width hardly changed as the air flow rate increased from 0.5 m3/h to 1.0 m3/h. This study is expected to provide reference for promoting the application of pulsed corona discharge plasma to chitosan solution treatment. (plasma technology)

  18. Influence of gas discharge parameters on emissions from a dielectric barrier discharge excited argon excimer lamp

    Directory of Open Access Journals (Sweden)

    Mike Collier

    2011-11-01

    Full Text Available A dielectric barrier discharge excited neutral argon (Ar I excimer lamp has been developed and characterised. The aim of this study was to develop an excimer lamp operating at atmospheric pressure that can replace mercury lamps and vacuum equipment used in the sterilisation of medical equipment and in the food industry. The effects of discharge gas pressure, flow rate, excitation frequency and pulse width on the intensity of the Ar I vacuum ultraviolet (VUV emission at 126 nm and near infrared (NIR lines at 750.4 nm and 811.5 nm have been investigated. These three lines were chosen as they represent emissions resulting from de-excitation of excimer states that emit energetic photons with an energy of 9.8 eV. We observed that the intensity of the VUV Ar2* excimer emission at 126 nm increased with increasing gas pressure, but decreased with increasing excitation pulse frequency and pulse width. In contrast, the intensities of the NIR lines decreased with increasing gas pressure and increased with increasing pulse frequency and pulse width. We have demonstrated that energetic VUV photons of 9.8 eV can be efficiently generated in a dielectric barrier discharge in Ar.

  19. The development of dielectric barrier discharges in gas gaps and on surfaces

    International Nuclear Information System (INIS)

    Dielectric barrier discharges (DBDs) occur in configurations which are characterized by a dielectric layer between conducting electrodes. Two basic configurations can be distinguished: a volume discharge (VD) arrangement with a gas gap; and a surface discharge (SD) arrangement with surface electrode(s) on a dielectric layer and an extensive counter electrode on its reverse side. At atmospheric pressure the DBD consists of numerous microdischarges (VD) and discharge steps (SD), respectively, their number being proportional to the amplitude of the voltage. These events have a short duration in the range of some 10 ns transferring a certain amount of charge within the discharge region. The total transferred charge determines the current and hence the volt-ampere characteristic of each arrangement. The microdischarges (discharge steps) have a complicated spatial structure. The discharge patterns on the dielectric surface depend on the polarity and amplitude of the applied voltage as well as on the specific capacity of the dielectric. Experimental findings on DBDs in air and oxygen are presented and discussed. On the basis of a self-consistent two-dimensional modelling the temporal and spatial development of a microdischarge and discharge step are investigated numerically. The results lead to an understanding of the dynamics of DBDs. Although in VD arrangements cathode-directed streamers appear especially in electronegative gases, their appearance is rather unlikely in SD arrangements. The application of DBDs for plasma-chemical reactions is determined by the productivity, with which the energy of the electric field can be converted into internal states of atoms and/or molecules. Depending on the desired product it could be both the generation of internal electronic states of molecules or atoms and dissociation products of molecules. The discharge current and current density of DBDs in both the SD and VD arrangements as well as the energy release and energy density

  20. Dynamics of the atmospheric pressure diffuse dielectric barrier discharge between cylindrical electrodes in roll-to-roll PECVD reactor

    Science.gov (United States)

    Starostin, Sergey A.; Welzel, Stefan; Liu, Yaoge; van der Velden-Schuermans, Bernadette; Bouwstra, Jan B.; van de Sanden, Mauritius C. M.; de Vries, Hindrik W.

    2015-07-01

    The high current diffuse dielectric barrier discharge (DBD) was operated in a bi-axial cylindrical electrode configuration using nitrogen, oxygen and argon gas flow with the addition of tetraethyl orthosilicate as precursor for silica-like film deposition. The behaviour of the transient plasma was visualized by means of fast imaging from two orthogonal directions. The formation and propagation (~3 × 104 m s-1) of lateral ionization waves with the transverse light emission structure similar to the low pressure glow discharge was observed at time scales below 1 µs. Despite plasma non-uniformity at nanosecond time scale the deposition process on the web-rolled polymer results in smooth well adherent films with good film uniformity and excellent gas diffusion barrier properties. Contribution to the topical issue "The 14th International Symposium on High Pressure Low Temperature Plasma Chemistry (HAKONE XIV)", edited by Nicolas Gherardi, Ronny Brandenburg and Lars Stollenwark

  1. Study on the Microsecond Pulse Homogeneous Dielectric Barrier Discharges in Atmospheric Air and Its Influencing Factors

    International Nuclear Information System (INIS)

    The homogeneous dielectric barrier discharge (DBD) in atmospheric air between two symmetric-columnar copper electrodes with epoxy plates as the dielectric barriers is generated using a μs pulse high voltage power supply. The discharge characteristics are studied by measurement of its electrical discharge parameters and observation of its light emission phenomena, and the main discharge parameters of the homogenous DBD, such as discharge current and average discharge power, are calculated. Results show that the discharge generated is a homogeneous one with one larger single current pulse of about 2 μs duration appearing in each voltage pulse, and its light emission is radially homogeneous and covers the entire surface of the two electrodes. The influences of applied voltage amplitude, air gap distance and barrier thickness on the transition of discharge modes are studied. With the increase of air gap distance, the discharge will transit from homogeneous mode to filamentary mode. The higher the thickness of dielectric barriers, the larger the air gap distance for generating the homogeneous discharge mode. The average discharge power increases non-linearly with increasing applied voltage amplitude, and decreases non-linearly with the increase of air gap distance and barrier thickness. In order to generate stable and homogeneous DBD with high discharge power, thin barriers distance should be used, and higher applied voltage amplitude should be applied to small air gap. (15th asian conference on electrical discharge)

  2. Preparation of Copper Nanoparticles Using Dielectric Barrier Discharge at Atmospheric Pressure and its Mechanism

    International Nuclear Information System (INIS)

    Dielectric barrier discharge (DBD) cold plasma at atmospheric pressure was used for preparation of copper nanoparticles by reduction of copper oxide (CuO). Power X-ray diffraction (XRD) was used to characterize the structure of the copper oxide samples treated by DBD plasma. Influences of H2 content and the treating time on the reduction of copper oxide by DBD plasma were investigated. The results show that the reduction ratio of copper oxide was increased initially and then decreased with increasing H2 content, and the highest reduction ratio was achieved at 20% H2 content. Moreover, the copper oxide samples were gradually reduced by DBD plasma into copper nanoparticles with the increase in treating time. However, the average reduction rate was decreased as a result of the diffusion of the active hydrogen species. Optical emission spectra (OES) were observed during the reduction of the copper oxide samples by DBD plasma, and the reduction mechanism was explored accordingly. Instead of high-energy electrons, atomic hydrogen (H) radicals, and the heating effect, excited-state hydrogen molecules are suspected to be one kind of important reducing agents. Atmospheric-pressure DBD cold plasma is proved to be an efficient method for preparing copper nanoparticles. (plasma technology)

  3. Dielectric barrier discharge control and thrust enhancement by diode surface

    Science.gov (United States)

    Starikovskiy, Andrey; Post, Martiqua; Tkach, Nickolas; Miles, Richard; PU Team

    2013-09-01

    The problem of the charge removal is very simple: we need a surface which will conduct the current in one direction and will have high resistance in another to avoid the leakage during the forward discharge development. Lateral diode string structures were designed and successfully manufactured on a 3-inch 4H-SiC semi-insulating wafer. The experiments with direct thrust measurements at low pressure conditions were performed as well as experiments of jet formation at pressure P = 1 atm. It was shown that the plasma conductivity is limiting the charge transfer through the surface. The minimal pulse width value could be estimated as a plasma recombination time. The surface becomes effective suppressor for the reverse breakdown when the conductivity of plasma layer is small enough with compare to the surface conductivity. It means that the reverse breakdown with nanosecond-range delay removes efficiently all surface charges. Effective flow acceleration using diode surface is possible with long pulses with allow full plasma recombination between leading and trailing pulse fronts.

  4. Characterization of surface dielectric barrier discharge influenced by intermediate frequency for ozone production

    Science.gov (United States)

    Abdelaziz, Ayman A.; Ishijima, Tatsuo; Seto, Takafumi; Osawa, Naoki; Wedaa, Hassan; Otani, Yoshio

    2016-06-01

    The aim of this study is to investigate the effect of the intermediate frequency (1–10 kHz) of the sinusoidal driving voltage on the characteristics of a developed surface dielectric barrier discharge (SDBD)-based reactor having spikes on its discharge electrode. Moreover, its influence on the production of ozone and nitrogen oxide byproducts is evaluated. The results show that SDBD is operated in the filamentary mode at all the frequencies. Nevertheless, the pulses of the discharge current at high frequencies are much denser and have higher amplitudes than those at low frequencies. The analysis of the power consumed in the reactor shows that a small portion of the input power is dissipated in the dielectric material of SDBD source, whereas the major part of the power is consumed in the plasma discharge. The results of the ozone production show that higher frequencies have a slightly adverse effect on the ozone production at relatively high energy density values, where the ozone concentration is slightly decreased when the frequency is increased at the same energy density. The temperature of the discharge channels and gas is not a crucial factor for the decomposition of ozone in this reactor, while the results of the measurements of nitrogen oxides characteristics indicate that the formation of NO and NO2 has a significant adverse effect on the production efficiency of ozone due to their oxidation to another nitrogen oxides and their catalytic effect.

  5. Degradation of Aniline Wastewater Using Dielectric Barrier Discharges at Atmospheric Pressure

    Science.gov (United States)

    WU, Haixia; FANG, Zhi; XU, Yanhua

    2015-03-01

    Aniline is a toxic water pollutant detected in drinking water and surface water, and this chemical is harmful to both human and aquatic life. A dielectric barrier discharge (DBD) reactor was designed in this study to investigate the treatment of aniline in aqueous solution. Discharge characteristics were assessed by measuring voltage and current waveforms, capturing light emission images, and obtaining optical emission spectra. The effects of several parameters were analyzed, including treatment distance, discharge power, DBD treatment time, initial pH of aniline solutions, and addition of sodium carbonate and hydrogen peroxide to the treatment. Aniline degradation increased with increasing discharge power. Under the same conditions, higher degradation was obtained at a treatment distance of 0 mm than at other treatment distances. At a discharge power of 21.5 W, 84.32% of aniline was removed after 10 min of DBD treatment. Initial pH significantly influenced aniline degradation. Adding a certain dosage of sodium carbonate and hydrogen peroxide to the wastewater can accelerate the degradation rate of aniline. Possible degradation pathways of aniline by DBD plasmas were proposed based on the analytical data of GC/MS and TOC. supported by National Natural Science Foundation of China (No. 51377075), the Natural Science Foundation of Jiangsu Province of China (No. BK20131412), the Environmental Protection Scientific Foundation of Jiangsu Province of China (No. 201004)

  6. Force measurements of single and double barrier DBD plasma actuators in quiescent air

    Energy Technology Data Exchange (ETDEWEB)

    Hoskinson, A R; Hershkowitz, N [Department of Engineering Physics, University of Wisconsin - Madison, 1500 Engineering Dr., Madison, WI 53706 (United States); Ashpis, D E [National Aeronautics and Space Administration, Glenn Research Center at Lewis Field, Cleveland, OH 44135 (United States)], E-mail: arhoskinson@wisc.edu, E-mail: hershkowitz@engr.wisc.edu

    2008-12-21

    We present the results of our experimental measurements of how variations in the discharge geometry of surface-mounted dielectric barrier discharges (DBDs) affect the force transferred to atmospheric pressure air. Our studies include both single barrier plasma actuators (one electrode insulated) and double barrier plasma actuators (both electrodes insulated) operated in quiescent air. Stagnation probe measurements of the induced air flow and direct force measurements using an electronic balance show that, for both actuator types, parallel time-averaged forces increase as the high voltage electrode diameter decreases. For single barrier actuators, this increase is exponential rather than linear as previously reported in the literature. The data from the two measurement techniques are directly proportional to one another. When the variation of velocity and pressure on all sides of an actuator are considered, the techniques show quantitative agreement.

  7. Properties of corona discharge plasma near metal surface

    Science.gov (United States)

    Lavrinenko, M.; Biktashev, E.; Kirko, D.

    2016-01-01

    Properties of corona discharge near metallic surface were researched. Electrical oscillations in discharge plasma of 1 kHz - 100 MHz rate were registered. Spectrum of electrical oscillations in this range was obtained. Possible plasma waves for observed electronic oscillations explanation are discussed.

  8. Spectroscopic measurements of electric field distributions in dielectric barrier discharges in hydrogen

    International Nuclear Information System (INIS)

    The results of spectroscopic studies of plasmas generated in dielectric barrier discharges between flat ceramic electrodes supplied by AC voltage in pure hydrogen atmosphere under low-pressure conditions are presented. Stark splitting of the Hα Balmer line was used to measure the electric field strengths in the discharge volume. The optical instrumentation and the detection system allow to perform spatial and time resolved measurements separately for the π and σ Stark components. The measured spatial light intensity distributions are averaged data obtained by integrating signals from many half-periods of the AC voltage supply. This fact has been taken into account when comparing our averaged data with results of theoretical models which are yielding time dependent results

  9. Monolithic structure of integrated coaxial microhollow dielectric barrier discharges: Characterization for environmental and biomedical applications

    Science.gov (United States)

    Tachibana, Kunihide; Nakamura, Toshihiro; Motomura, Hideki

    2016-07-01

    The characteristics of microhollow dielectric barrier discharge devices in a thin monolithic planar structure with many holes were analyzed regarding the production of OH radicals, using optical emission and laser-induced fluorescence (LIF) spectroscopy techniques. Spatial distributions of OH radical density depended on the diameter of electrode holes from 0.6 to 1.5 mm and the discharge operating gas species. Apparent emission intensity from OH radicals and the LIF signals were very high in He and Ar gases but quite low in N2. However, taking into account the LIF quenching rate in each gas, the existing densities of OH radicals in all tested gases were not greatly different from each other. The absolute density of OH radicals estimated by a comparison of the LIF intensity with our measured result on a conventional He plasma jet referring to reported densities in similar situations was on the order of 1014 cm‑3.

  10. Mach 5 bow shock control by a nanosecond pulse surface dielectric barrier discharge

    International Nuclear Information System (INIS)

    Bow shock perturbations in a Mach 5 air flow, produced by low-temperature, nanosecond pulse, and surface dielectric barrier discharge (DBD), are detected by phase-locked schlieren imaging. A diffuse nanosecond pulse discharge is generated in a DBD plasma actuator on a surface of a cylinder model placed in air flow in a small scale blow-down supersonic wind tunnel. Discharge energy coupled to the actuator is 7.3-7.8 mJ/pulse. Plasma temperature inferred from nitrogen emission spectra is a few tens of degrees higher than flow stagnation temperature, T = 340 ± 30 K. Phase-locked Schlieren images are used to detect compression waves generated by individual nanosecond discharge pulses near the actuator surface. The compression wave propagates upstream toward the baseline bow shock standing in front of the cylinder model. Interaction of the compression wave and the bow shock causes its displacement in the upstream direction, increasing shock stand-off distance by up to 25%. The compression wave speed behind the bow shock and the perturbed bow shock velocity are inferred from the Schlieren images. The effect of compression waves generated by nanosecond discharge pulses on shock stand-off distance is demonstrated in a single-pulse regime (at pulse repetition rates of a few hundred Hz) and in a quasi-continuous mode (using a two-pulse sequence at a pulse repetition rate of 100 kHz). The results demonstrate feasibility of hypersonic flow control by low-temperature, repetitive nanosecond pulse discharges.

  11. Treatment of polycarbonate by dielectric barrier discharge (DBD) at atmospheric pressure

    Science.gov (United States)

    Kostov, K. G.; Hamia, Y. A. A.; Mota, R. P.; dos Santos, A. L. R.; Nascente, P. A. P.

    2014-05-01

    Generally most plastic materials are intrinsically hydrophobic, low surface energy materials, and thus do not adhere well to other substances. Surface treatment of polymers by discharge plasmas is of great and increasing industrial application because it can uniformly modify the surface of sample without changing the material bulk properties and is environmentally friendly. The plasma processes that can be conducted under ambient pressure and temperature conditions have attracted special attention because of their easy implementation in industrial processing. Present work deals with surface modification of polycarbonate (PC) by a dielectric barrier discharge (DBD) at atmospheric pressure. The treatment was performed in a parallel plate reactor driven by a 60Hz power supply. The DBD plasmas at atmospheric pressure were generated in air and nitrogen. Material characterization was carried out by contact angle measurements, and X-ray photoelectron spectroscopy (XPS). The surface energy of the polymer surface was calculated from contact angle data by Owens-Wendt method using distilled water and diiodomethane as test liquids. The plasma-induced chemical modifications are associated with incorporation of polar oxygen and nitrogen containing groups on the polymer surface. Due to these surface modifications the DBD-treated polymers become more hydrophilic. Aging behavior of the treated samples revealed that the polymer surfaces were prone to hydrophobic recovery although they did not completely recover their original wetting properties.

  12. Operation of Ferroelectric Plasma Sources in a Gas Discharge Mode

    International Nuclear Information System (INIS)

    Ferroelectric plasma sources in vacuum are known as sources of ablative plasma, formed due to surface discharge. In this paper, observations of a gas discharge mode of operation of the ferroelectric plasma sources (FPS) are reported. The gas discharge appears at pressures between approximately 20 and approximately 80 Torr. At pressures of 1-20 Torr, there is a transition from vacuum surface discharge to the gas discharge, when both modes coexist and the surface discharges sustain the gas discharge. At pressures between 20 and 80 Torr, the surface discharges are suppressed, and FPS operate in pure gas discharge mode, with the formation of almost uniform plasma along the entire surface of the ceramics between strips. The density of the expanding plasma is estimated to be about 1013 cm-3 at a distance of 5.5 mm from the surface. The power consumption of the discharge is comparatively low, making it useful for various applications. This paper also presents direct measurements of the yield of secondary electron emission from ferroelectric ceramics, which, at low energies of primary electrons, is high and dependent on the polarization of the ferroelectric material

  13. Dependence of corona discharge plasma on voltage pulse characteristics

    International Nuclear Information System (INIS)

    The dynamical behavior of corona discharge plasma at atmospheric pressure has been investigated. The plasma is produced in a coaxial chamber of 1 inch inner diameter, where high voltage pulses of 10 to 30 kV are applied. The properties of the discharge plasma depend strongly on the pulse characteristics, i.e., voltage strength, pulse width, pulse repetition frequency. At a voltage of less than 15 kV, a corona discharge is produced near the center electrode. Subsequently, as the applied voltage is increased, arcing begins. The authors believe it is due to the fact that in the low voltage case, the self energy for instability is not sufficiently high to cause plasma disruption. Though spurious arcing occurs at higher voltages, a glow or sustained plasma dominates as the pulse repetition frequency is increased. The time resolved discharge data shows a monotonically increasing characteristic impedance with nearly constant discharge current. It appears that the plasma at the end of a pulse does not immediately disappear, but remains in the chamber to help ignite plasma at the next pulse as a seed plasma. These observed behaviors will be compared with the numerical results from transport equations. Finally, as an application of this corona discharge plasma for air purification, the effectiveness on the gas destruction rate will be compared between plasmas produced at different voltage characteristics

  14. Degradation of TAIC by water falling film dielectric barrier discharge – Influence of radical scavengers

    International Nuclear Information System (INIS)

    Highlights: • Degradation of TAIC by water falling film dielectric barrier discharge. • Two kings of radical scavengers all could enhance the TAIC degradation. • Both kings of radical scavengers could promote the generation of H2O2. • A novel method of the mixed additives of Fe2+ and radical scavengers were employed. - Abstract: This work describes the application of plasma generated by water falling film dielectric barrier discharge for the degradation of triallyl isocyanurate (TAIC). The results indicated that TAIC solution of 1000 mg/L was effectively removed within 60 min treatment at 120 W output power. Six intermediates were identified and a possible evolution of the TAIC degradation process was continuously proposed basing on the results of mass spectrum analysis. The effects of metal ions and radical scavengers were investigated. Results showed that whatever hydrogen radical scavengers (carbon tetrachloride, perfluorooctane) or hydroxyl radical scavengers (iso-propyl alcohol, tert-butyl alcohol) all could further enhance the degradation processes, and both kings of radical scavengers could promote the generation of H2O2. In the present study, we employed a novel method by introducing the mixed additives of Fe2+ and radical scavengers into the plasma. It was found that the reaction rate constant and energy efficiency were improved by 309.2% and 387.8%, respectively. Among the mixed additives, Fe2+ could promote the decomposition and increase the oxidizing power of H2O2, which is generated from the plasma discharge and greatly enhanced by the radical scavengers

  15. Mass analysis of trifluoro-iodo-methane in a Surface Barrier Discharge

    Science.gov (United States)

    Rees, J. A.; Greenwood, C. L.; Lundie, D. T.; Seymour, D. L.; Hiden Analytical Team

    2011-10-01

    Surface barrier discharges operated at atmospheric pressure are effective chemical reactors. Mass analysis of the reaction products is possible using suitable high pressure mass spectrometer systems. As an example of the behaviour of simple surface barrier reactor (SBDs), experiments on the decomposition of CF3I are described in which the output from the reactor is admitted via a capillary inlet system into a Hiden HPR20 mass spectrometer. The discharge was operated using helium as the carrier gas. The observed mass spectra are discussed in terms of the plasma dissociation and the subsequent ionisation of the dissociated products in the electron impact ionisation source of the mass spectrometer. When oxygen was added to the gas mixture in the SBD, CFxO species were generated in the plasma. Their influence on the observed mass spectra is shown. The results demonstrate aspects of the capabilities of SBDs for dissociating halocarbon gases at atmospheric pressure and the possibilities of direct mass spectrometric monitoring of such processes.

  16. Effect of glow discharge air plasma on grain crops seed

    Energy Technology Data Exchange (ETDEWEB)

    Dubinov, A.E.; Lazarenko, E.M.; Selemir, V.D.

    2000-02-01

    Oat and barley seeds have been exposed to both continuous and pulsed glow discharge plasmas in air to investigate the effects on germination and sprout growth. Statistical analysis was used to evaluate the effect of plasma exposure on the percentage germination and length of sprout growth. A stimulating effect of plasma exposure was found together with a strong dependence on whether continuous or pulsed discharges were used.

  17. Removal of low-concentration formaldehyde in indoor air by DC corona discharge plasma

    Energy Technology Data Exchange (ETDEWEB)

    Fan, X.; Wan, Y.; Zhu, T. [Beihang Univ., Beijing (China). School of Chemistry and Environment

    2010-07-01

    Low-concentration formaldehyde (HCHO) is a major indoor air pollutant in China and is the subject of public concern because of its adverse health effects. Non-thermal plasma is a promising method to remove indoor HCHO. NTP is known to remove various pollutants such as particulate matter, bacteria and volatile organic compounds (VOCs) simultaneously under ambient conditions. In recent years, dielectric barrier discharge (DBD) plasma reactors have been developed for HCHO removal, mainly at much higher concentration levels than those found in indoor environments. This study examined the effects of discharge polarity, discharge electrode configuration and combined catalyst on the removal of low-concentration HCHO in air using a link tooth wheel-cylinder plasma reactor energized by a DC power. The study showed that the positive DC corona discharge is much more effective in removing HCHO compared to the negative DC corona discharge. The discharge electrode configuration has little influence on the HCHO conversion for a given specific input energy, but it significantly affects the energy input in the plasma reactor. Combining NTP with a MnOx/Al2O3 catalyst after the discharge zone significantly promoted HCHO conversion and reduced ozone emissions. 8 refs., 5 figs.

  18. A combined study for turning CO$_2$ and H$_2$O into value-added products in a dielectric barrier discharge

    CERN Document Server

    Snoeckx, Ramses; Aerts, Robby; Dufour, Thierry; Reniers, François; Bogaerts, Annemie

    2016-01-01

    A combination of experiments and extensive modelling, including a chemical kinetics analysis, was performed for a CO$_2$/H$_2$O plasma in a dielectric barrier discharge. This provides a better understanding of the mechanisms related to the reactivity of the plasma and of the conversions into value-added products, such as methanol.

  19. Laser absorption spectroscopy diagnostics of helium metastable atoms generated in dielectric barrier discharge cryoplasmas

    Science.gov (United States)

    Urabe, Keiichiro; Muneoka, Hitoshi; Stauss, Sven; Sakai, Osamu; Terashima, Kazuo

    2015-10-01

    Cryoplasmas, which are plasmas whose gas temperatures are below room temperature (RT), have shown dynamic changes in their physical and chemical characteristics when the gas temperature in the plasmas (Tgp) was decreased from RT. In this study, we measured the temporal behavior of helium metastable (Hem) atoms generated in a parallel-plate dielectric barrier discharge at ambient gas temperatures (Tga) of 300, 100, and 14 K and with a gas density similar to atmospheric conditions by laser absorption spectroscopy. The increments of Tgp to Tga were less than 20 K. We found from the results that the Hem lifetime and maximum density become longer and larger over one order of magnitude for lower Tga. The reasons for the long Hem lifetime at low Tga are decreases in the rate coefficients of three-body Hem quenching reactions and in the amounts of molecular impurities with boiling points higher than that of He.

  20. Surface modification for biomedical purposes utilizing dielectric barrier discharges at atmospheric pressure

    International Nuclear Information System (INIS)

    Using dielectric barrier discharges (DBD) at atmospheric pressure, glass or polymer surfaces were equipped with epoxide groups or amino groups by plasma deposition from suitable monomers or - in case of polymers - DBD treatment in nitrogen-containing gases. Functional group densities have been estimated using absorption and fluorescence measurements or by X-ray photoelectron spectroscopy. Amino group densities are comparable or even larger than those of aminosilylated surfaces. Fluorescence-labeled streptavidin has been used to investigate the binding capacity of surfaces equipped with covalently bound biotin molecules, starting either from epoxide or from amino groups. As an example of a Plasma Printing process, the generation of an array amino-functionalized spots, 400-μm in diameter on a polymer surface by local deposition from aminopropyl-trimethoxysilane is demonstrated

  1. Robust, Flexible and Lightweight Dielectric Barrier Discharge Actuators Using Nanofoams/Aerogels

    Science.gov (United States)

    Sauti, Godfrey (Inventor); Xu, Tian-Bing (Inventor); Siochi, Emilie J. (Inventor); Wilkinson, Stephen P. (Inventor); Meador, Mary Ann B. (Inventor); Guo, Haiquan N. (Inventor)

    2015-01-01

    Robust, flexible, lightweight, low profile enhanced performance dielectric barrier discharge actuators (plasma actuators) based on aerogels/nanofoams with controlled pore size and size distribution as well as pore shape. The plasma actuators offer high body force as well as high force to weight ratios (thrust density). The flexibility and mechanical robustness of the actuators allows them to be shaped to conform to the surface to which they are applied. Carbon nanotube (CNT) based electrodes serve to further decrease the weight and profile of the actuators while maintaining flexibility while insulating nano-inclusions in the matrix enable tailoring of the mechanical properties. Such actuators are required for flow control in aeronautics and moving machinery such as wind turbines, noise abatement in landing gear and rotary wing aircraft and other applications.

  2. Dielectric barrier discharge actuator for vehicle drag reduction at highway speeds

    Directory of Open Access Journals (Sweden)

    Subrata Roy

    2016-02-01

    Full Text Available We propose and demonstrate reduction of aerodynamic drag for a realistic geometry at highway speeds using serpentine dielectric barrier discharge actuators. A comparable linear plasma actuator fails to reduce the drag at these speeds. Experimental data collected for linear and serpentine plasma actuators under quiescent operating conditions show that the serpentine design has profound effect on near wall flow structure and resulting drag. For certain actuator arrangement, the measured drag reduced by over 14% at 26.8 m/s (60 mph and over 10% at 31.3 m/s (70 mph opening up realistic possibility of reasonable energy savings for full scale ground vehicles. In addition, the power consumption data and drag reduction effectiveness for different input signals are also presented.

  3. Filaments and feelers: UV and visible imaging of Xe excimer dielectric barrier discharge lamps

    International Nuclear Information System (INIS)

    Full text: Xenon excimer dielectric barrier discharge (DBD) lamps are efficient sources (>10%) of vacuum ultraviolet (VUV) radiation (∼175nm) that have diverse applications including plasma display panels, photochemical surface modification, ozone generation, and bacteria sterilisation. A significant increase in the efficiency (2-3 times) has been recently reported for these lamps when excited using fast-rising sub-microsecond pulses rather than the usual ∼ kHz sinewave. Visual inspection of the emission from the lamp suggested that the discharge was more uniform in the former case. To confirm this observation, and increase our understanding of the improved efficiency of pulsed DBD lamp, we have used a gated image intensifier coupled to a CCD to obtain time-resolved images in the visible, and for the first time (to our knowledge) in the VUV, for both pulsed and AC discharges. The lamp used for these measurements consisted of two fused silica plates separated by a 3 mm discharge gap: a VUV -transparent gold grid was deposited on the surface through which the discharge was viewed, while a wire mesh was used as the other electrode. The VUV was imaged by a CaF2 lens on to a sodium salicylate phosphor screen placed at the end of a nitrogen-flushed cylindrical chamber: the visible image from this screen was imaged on to the intensifier with a conventional camera lens. The visible and VUV images reveal that the pulsed discharge is notably more diffuse than the AC discharge as expected from the prior visual observations. The emitting region is essentially uniform, occupying most of the lamp's electrode area. Interestingly, however, the visible images of the AC-driven lamp reveal very fine spots suggestive of much thinner filaments between the electrodes than that indicated by the VUV images. The visible images also showed another surprising feature of the DBD discharge: distinct tracks of glowing gas which tend to be originate from the filaments formed a web covering

  4. OH density measurement by time-resolved broad band absorption spectroscopy in an Ar–H2O dielectric barrier discharge

    Czech Academy of Sciences Publication Activity Database

    Dilecce, G.; Ambrico, P. F.; Šimek, Milan; De Benedictis, S.

    2012-01-01

    Roč. 45, č. 12 (2012), s. 125203-125203. ISSN 0022-3727 Institutional research plan: CEZ:AV0Z20430508 Keywords : Spectroscopic Techniques * Plasma Diagnostics * LIF * OH * Dielectric Barrier Discharge Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.528, year: 2012 http://iopscience.iop.org/0022-3727/45/12/125203/pdf/0022-3727_45_12_125203.pdf

  5. Study on hexagonal super-lattice pattern with surface discharges in dielectric barrier discharge

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ying; Dong, Lifang, E-mail: donglfhbu@163.com; Niu, Xuejiao; Gao, Yenan; Zhang, Chao [College of Physics Science and Technology, Hebei University, Baoding 071002 (China); Hebei Key Laboratory of Optic-electronic Information Materials, Baoding 071002 (China)

    2015-10-15

    The hexagonal super-lattice pattern with surface discharges (SDs) in dielectric barrier discharge is investigated by intensified charge-coupled device. The pattern is composed of the bright spot and the dim spot which is located at the centroid of surrounding other three bright spots. The phase diagram of the pattern as a function of the gas pressure and the argon concentration is given. The instantaneous images indicate that the bright spot emerging at the front of the current pulse is formed by the volume discharge (VD), and dim spot occurring at the tail of the current pulse is formed by the SD. The above result shows that the SD is induced by the VD. The simulation of the electric fields of wall charges accumulated by VDs confirms that the dim spot is formed by the confluences of the SDs of surrounding other three bright spots. By using optical emission spectrum method, both the molecule vibration temperature and electron density of the SD are larger than that of the VD.

  6. Study on hexagonal super-lattice pattern with surface discharges in dielectric barrier discharge

    Science.gov (United States)

    Liu, Ying; Dong, Lifang; Niu, Xuejiao; Gao, Yenan; Zhang, Chao

    2015-10-01

    The hexagonal super-lattice pattern with surface discharges (SDs) in dielectric barrier discharge is investigated by intensified charge-coupled device. The pattern is composed of the bright spot and the dim spot which is located at the centroid of surrounding other three bright spots. The phase diagram of the pattern as a function of the gas pressure and the argon concentration is given. The instantaneous images indicate that the bright spot emerging at the front of the current pulse is formed by the volume discharge (VD), and dim spot occurring at the tail of the current pulse is formed by the SD. The above result shows that the SD is induced by the VD. The simulation of the electric fields of wall charges accumulated by VDs confirms that the dim spot is formed by the confluences of the SDs of surrounding other three bright spots. By using optical emission spectrum method, both the molecule vibration temperature and electron density of the SD are larger than that of the VD.

  7. Discharge behaviors during plasma electrolytic oxidation on aluminum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Run [Key Laboratory for Beam Technology and Materials Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Zhenjiang Watercraft College, Zhenjiang 212000, Jiangsu (China); Wu, Jie [Key Laboratory for Beam Technology and Materials Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Xue, Wenbin, E-mail: xuewb@bnu.edu.cn [Key Laboratory for Beam Technology and Materials Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Qu, Yao; Yang, Chaolin; Wang, Bin; Wu, Xianying [Key Laboratory for Beam Technology and Materials Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China)

    2014-11-14

    A plasma electrolytic oxidation (PEO) process was performed on the 2024 aluminum alloy in silicate electrolyte to fabricate ceramic coatings under a constant voltage. Optical emission spectroscopy (OES) was employed to evaluate the characteristics of plasma discharge during PEO process. The plasma electron temperature and density were obtained by analyzing the spectral lines of OES, and the atomic ionization degree in discharge zone was calculated in terms of Saha thermal ionization equation. The illumination intensity of plasma discharge and the temperature in the interior of alloy were measured. Combining the surface morphology and cross-sectional microstructure with the optical emission spectra and illumination at different discharge stage, a discharge model in the growth of PEO ceramic coatings was proposed. It is found that there are two discharge modes of type A with small spark size and type B with large spark size, and the latter only appears in the intermediate stage of PEO process. The illumination intensity has a maximum value in the initial stage of oxidation with many sparks of discharge type A. The electron temperature in plasma discharge zone is about 3000 K–7000 K and atomic ionization degree of Al is about 2.0 × 10{sup −5}–7.2 × 10{sup −3}, which depend on discharge stage. The discharge type B plays a key role on the electron temperature and atomic ionization degree. The electron density keeps stable in the range of about 8.5 × 10{sup 21} m{sup −3}–2.6 × 10{sup 22} m{sup −3}. - Highlights: • The characteristics of PEO plasma discharge was evaluated by OES. • Electron temperature, concentration, atomic ionization degree were calculated. • Discharge model for the growth of PEO coatings was proposed. • Temperature in the interior of alloy during PEO process was measured.

  8. Methane Conversion Using Dielectric Barrier Discharge: Comparison with Thermal Process and Catalyst Effects

    Institute of Scientific and Technical Information of China (English)

    Antonius Indarto; Jae-Wook Choi; Hwaung Lee; Hyung Keun Song

    2006-01-01

    The direct conversion of methane using a dielectric barrier discharge has been experimentally studied. Experiments with different values of flow rates and discharge voltages have been performed to investigate the effects on the conversion and reaction products both qualitatively and quantitatively.Experimental results indicate that the maximum conversion of methane has been 80% at an input flow rate of 5 ml/min and a discharge voltage of 4 kV. Experimental results also show that the optimum condition has occurred at a high discharge voltage and higher input flow rate. In terms of product distribution, a higher flow rate or shorter residence time can increase the selectivity for higher hydrocarbons. No hydrocarbon product was detected using the thermal method, except hydrogen and carbon. Increasing selectivity for ethane was found when Pt and Ru catalysts presented in the plasma reaction. Hydrogenation of acetylene in the catalyst surface could have been the reason for this phenomenon as the selectivity for acetylene in the products was decreasing.

  9. Experimental and computational study of dielectric barrier discharges for environmental applications

    Science.gov (United States)

    Aerts, Robby

    Air pollution has become a major global concern which affects all inhabitants of our precious earth. Nowadays it is fact that our climate is changing and the sea level is rising. Moreover, we are facing an energy crisis because all our fossil fuel resources will sooner or later be running empty. It is clear that drastic measures are needed to keep our planet as it is today for generations to come. One of these measures is the 20-20-20 targets imposed by the European Commission, which stimulates the research for environmental energy applications. In this PhD dissertation two environmental applications of plasma technology are investigated. The first one is the abatement of flue gases, and more specifically the destruction of volatile organic compounds (VOCs). The second one is the conversion of CO2 into valuable chemicals. Both of these applications suffer from a large energy cost under classical (thermodynamic) conditions, due to the chemical stability of these molecules. Plasma technology is quite promising to overcome these thermodynamic barriers. Plasmas allow reactions at different time-scales with different species, such as electrons, ions, radicals, molecules and excited species, creating new chemical pathways. Indeed, in a plasma the applied electrical energy is directly transferred to the electrons, which activate the gas by ionization, excitation and dissociation, hence creating reactive species (ions, excited species, radicals), that can further easily undergo other chemical reactions. Especially gas discharges, which are low temperature plasmas, show promising results in the destruction of pollutants at mild conditions. A common type of gas discharge is the dielectric barrier discharge (DBD) which has been successfully scaled up for industrial ozone generation and is widely investigated in the field of environmental applications. The complexity of DBDs creates difficulties for experimental diagnostics and therefore numerical studies can help to improve

  10. Electron current extraction from radio frequency excited micro-dielectric barrier discharges

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jun-Chieh; Kushner, Mark J. [Electrical Engineering and Computer Science Department, University of Michigan, 1301 Beal Ave., Ann Arbor, Michigan 48109 (United States); Leoni, Napoleon; Birecki, Henryk; Gila, Omer [Hewlett Packard Research Labs, Palo Alto, California 94304 (United States)

    2013-01-21

    Micro dielectric barrier discharges (mDBDs) consist of micro-plasma devices (10-100 {mu}m diameter) in which the electrodes are fully or partially covered by dielectrics, and often operate at atmospheric pressure driven with radio frequency (rf) waveforms. In certain applications, it may be desirable to extract electron current out of the mDBD plasma, which necessitates a third electrode. As a result, the physical structure of the m-DBD and the electron emitting properties of its materials are important to its operation. In this paper, results from a two-dimensional computer simulation of current extraction from mDBDs sustained in atmospheric pressure N{sub 2} will be discussed. The mDBDs are sandwich structures with an opening of tens-of-microns excited with rf voltage waveforms of up to 25 MHz. Following avalanche by electron impact ionization in the mDBD cavity, the plasma can be expelled from the cavity towards the extraction electrode during the part of the rf cycle when the extraction electrode appears anodic. The electron current extraction can be enhanced by biasing this electrode. The charge collection can be controlled by choice of rf frequency, rf driving voltage, and permittivity of the dielectric barrier.

  11. Electron current extraction from radio frequency excited micro-dielectric barrier discharges

    International Nuclear Information System (INIS)

    Micro dielectric barrier discharges (mDBDs) consist of micro-plasma devices (10–100 μm diameter) in which the electrodes are fully or partially covered by dielectrics, and often operate at atmospheric pressure driven with radio frequency (rf) waveforms. In certain applications, it may be desirable to extract electron current out of the mDBD plasma, which necessitates a third electrode. As a result, the physical structure of the m-DBD and the electron emitting properties of its materials are important to its operation. In this paper, results from a two-dimensional computer simulation of current extraction from mDBDs sustained in atmospheric pressure N2 will be discussed. The mDBDs are sandwich structures with an opening of tens-of-microns excited with rf voltage waveforms of up to 25 MHz. Following avalanche by electron impact ionization in the mDBD cavity, the plasma can be expelled from the cavity towards the extraction electrode during the part of the rf cycle when the extraction electrode appears anodic. The electron current extraction can be enhanced by biasing this electrode. The charge collection can be controlled by choice of rf frequency, rf driving voltage, and permittivity of the dielectric barrier.

  12. Degradation of gaseous dioxin-like compounds with dielectric barrier discharges

    Energy Technology Data Exchange (ETDEWEB)

    Hung, Pao Chen; Chang, Shu Hao [Graduate Institute of Environmental Engineering, National Central University, Chungli 320, Taiwan (China); Chi, Kai Hsien [Research Center for Environmental Changes, Academia Sinica, Taipei 115, Taiwan (China); Chang, Moo Been, E-mail: mbchang@cc.ncu.eu.tw [Graduate Institute of Environmental Engineering, National Central University, Chungli 320, Taiwan (China)

    2010-10-15

    Developing effective technologies to reduce dioxin emissions has become an important issue in the research and industrial fields. In this study, a dioxin-containing gas stream generating system was applied to evaluate the effectiveness of dielectric barrier discharge (DBD) plasma technology for the destruction of dioxin-like compounds. The results indicate that the destruction efficiencies of dioxin-like compounds achieved with DBD plasma strongly depend on the composition of the simulated gas stream. As the DBD plasma is operated with the simulated gas stream containing 20% water vapor, around 74% PCDDs and 89% PCDFs can be destroyed by DBD plasma. UV, electrons, and OH radicals are generated via the DBD plasma process and react with the dioxin-like compounds in the gas stream. Dechlorination via UV and electrons and decomposition via OH radicals occur at the same time and significantly increase the destruction efficiency of PCDD/Fs in the presence of oxygen and water vapor. Additionally, the total toxicity destruction of dioxin-like compounds with the input energy of 1 kJ increases from 1.47 to 3.06 ng-TEQ{sub WHO} as the water vapor is incorporated into the gas stream.

  13. Degradation of gaseous dioxin-like compounds with dielectric barrier discharges.

    Science.gov (United States)

    Hung, Pao Chen; Chang, Shu Hao; Chi, Kai Hsien; Chang, Moo Been

    2010-10-15

    Developing effective technologies to reduce dioxin emissions has become an important issue in the research and industrial fields. In this study, a dioxin-containing gas stream generating system was applied to evaluate the effectiveness of dielectric barrier discharge (DBD) plasma technology for the destruction of dioxin-like compounds. The results indicate that the destruction efficiencies of dioxin-like compounds achieved with DBD plasma strongly depend on the composition of the simulated gas stream. As the DBD plasma is operated with the simulated gas stream containing 20% water vapor, around 74% PCDDs and 89% PCDFs can be destroyed by DBD plasma. UV, electrons, and OH radicals are generated via the DBD plasma process and react with the dioxin-like compounds in the gas stream. Dechlorination via UV and electrons and decomposition via OH radicals occur at the same time and significantly increase the destruction efficiency of PCDD/Fs in the presence of oxygen and water vapor. Additionally, the total toxicity destruction of dioxin-like compounds with the input energy of 1 kJ increases from 1.47 to 3.06 ng-TEQ(WHO) as the water vapor is incorporated into the gas stream. PMID:20605067

  14. On the stability of a homogeneous barrier discharge in nitrogen relative to radial perturbations

    CERN Document Server

    Golubovskii, Y B; Behnke, J; Behnke, J F

    2003-01-01

    The influence of small radial perturbations of the cathode current on the characteristics of a homogeneous barrier discharge in nitrogen is investigated on the basis of a two-dimensional fluid model. In a Townsend discharge, radial fluctuations are substantially suppressed, which is the evidence of its stability. The oscillative mode of the Townsend discharge is also stable with regard to radial perturbations. As the discharge turns into a form controlled by spatial charge (a streamer is developed), disturbances of all radii grow in time. Such a behaviour testifies the instability of a streamer front and may cause the discharge filamentation. Since only the Townsend discharge is stable, it is possible to use a one-dimensional model to determine the domain of existence for a homogeneous discharge. The study of homogeneity domains by means of the one-dimensional model shows that at relatively large values of the voltage growth rate, discharge gap width, or capacitance of dielectric barriers the discharge tends ...

  15. A gapless micro-dielectric-barrier-discharge ion source for analytical applications

    OpenAIRE

    Coy, Stephen L.; Krylov, Evgeny V.; Eiceman, Gary A.; Kanik, Isik

    2016-01-01

    Use of dielectric barrier discharge (DBD) as an ion source for sensitive chemical analysis is uncommon because barrier discharges generate excess noise due to spatial and temporal instability. This design uses contacted, crossed glass-coated micro-wires to focus the field into a gradually vanishing gap, suppressing spatial and temporal variability, reducing pressure, temperature, and humidity effects, stabilizing discharge initiation and limiting chemical fragmentation. Positive-ion-mode prot...

  16. Experimental Study of an Atmospheric Pressure Dielectric Barrier Discharge and PET Surface Modification

    OpenAIRE

    Shrestha, R; D. P. Subedi

    2015-01-01

    A homogeneous dielectric barrier discharge (DBD) in argon was produced by applying high voltage A.C. source of potential difference (0-20) kV operating at a frequency of 10-30 kHz across two parallel plate electrodes with glass as dielectric barrier. The discharge was characterized by optical emission spectroscopy (OES) and electrical measurement. Four argon emission lines from the discharge were analyzed and the electron temperature was estimated by line intensity ratio method. T...

  17. Effect of dielectric material on bipolar nanosecond pulse diffuse dielectric barrier discharge in air at atmospheric pressure

    Science.gov (United States)

    Tang, Kai; Wang, Wenchun; Yang, Dezheng; Zhang, Shuai; Yang, Yang; Liu, Zhijie

    2013-08-01

    In this paper, dielectric plates made by ceramic, quartz and polytetrafluoroethylene (PTFE) respectively are employed to generate low gas temperature, diffuse dielectric barrier discharge plasma by using a needle-plate electrode configuration in air at atmospheric pressure. Both discharge images and the optical emission spectra are obtained while ceramic, quartz and PTFE are used as dielectric material. Plasma gas temperature is also calculated by comparing the experimental emission spectra with the best fitted spectra of N2 (C3Πu → B3Πg 1-3) and N2 (C3Πu → B3Πg 0-2). The effects of different pulse peak voltages and gas gap distances on the emission intensity of N2 (C3Πu → B3Πg, 0-0, 337.1 nm) and the plasma area on dielectric surface are investigated while ceramic, quartz and PTFE are used as dielectric material. It is found that the permittivity of dielectric material plays an important role in the discharge homogeneity, plasma gas temperature, emission spectra intensity of the discharge, etc. Dielectric with higher permittivity i.e., ceramic means brighter discharge luminosity and stronger emission spectra intensity of N2 (C3Πu → B3Πg, 0-0, 337.1 nm) among the three dielectric materials. However, more homogeneous, larger plasma area on dielectric surface and lower plasma gas temperature can be obtained under dielectric with lower permittivity i.e., PTFE. The emission spectra intensity and plasma gas temperature of the discharge while the dielectric plate is made by quartz are smaller than that while ceramic is used as dielectric material and bigger than that when PTFE is used as dielectric material.

  18. Particle-in-cell modeling of gas-confined barrier discharge

    Science.gov (United States)

    Levko, Dmitry; Raja, Laxminarayan L.

    2016-04-01

    Gas-confined barrier discharge is studied using the one-dimensional Particle-in-Cell Monte Carlo Collisions model for the conditions reported by Guerra-Garcia and Martinez-Sanchez [Appl. Phys. Lett. 106, 041601 (2015)]. Depending on the applied voltage, two modes of discharge are observed. In the first mode, the discharge develops in the entire interelectrode gap. In the second mode, the discharge is ignited and develops only in the gas layer having smaller breakdown voltage. The one-dimensional model shows that for the conditions considered, there is no streamer stage of breakdown as is typical for a traditional dielectric barrier discharge.

  19. Methane from benzene in argon dielectric barrier discharge

    International Nuclear Information System (INIS)

    Highlights: ► Efficient on-line conversion of benzene to methane at room temperature. ► Absence of other H-atom donor suggests new type of chemistry. ► For parent loss > 90%, methane yield was ∼40% of limit due to H-atom availability. ► Surface moisture contributed ·OH radical for trace phenolic products’ formation. ► This method may emerge as an exploitable tactic for pollutants’ usable alterations. -- Abstract: A first-time account of direct, on-line, instantaneous and efficient chemical conversion of gas phase benzene to methane in argon Dielectric Barrier Discharge (DBD) is presented. In the absence of another overt hydrogen-donating source, potency of analogous parents toward methane generation is found to follow the order: benzene > toluene > p-xylene. Simultaneous production of trace amounts of phenolic surface deposits suggest (a) prompt decomposition of the parent molecules, including a large fraction yielding atomic transients (H-atom), (b) continuous and appropriate recombination of such parts, and (c) trace moisture in parent contributing ·OH radicals and additional H-atoms, which suitably react with the unreacted fraction of the parent, and also other intermediates. Results highlight Ar DBD to be a simple and exploitable technology for transforming undesirable hazardous aromatics to usable/useful low molecular weight open-chain products following the principles of green chemistry and engineering

  20. Statistical modelling of discharge behavior of atmospheric pressure dielectric barrier discharge

    Energy Technology Data Exchange (ETDEWEB)

    Tay, W. H.; Kausik, S. S.; Wong, C. S., E-mail: cswong@um.edu.my; Yap, S. L.; Muniandy, S. V. [Plasma Technology Research Centre, Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2014-11-15

    In this work, stochastic behavior of atmospheric pressure dielectric barrier discharge (DBD) has been investigated. The experiment is performed in a DBD reactor consisting of a pair of stainless steel parallel plate electrodes powered by a 50 Hz ac high voltage source. Current pulse amplitude distributions for different space gaps and the time separation between consecutive current pulses are studied. A probability distribution function is proposed to predict the experimental distribution function for the current pulse amplitudes and the occurrence of the transition regime of the pulse distribution. Breakdown voltage at different positions on the dielectric surface is suggested to be stochastic in nature. The simulated results based on the proposed distribution function agreed well with the experimental results and able to predict the regime of transition voltage. This model would be useful for the understanding of stochastic behaviors of DBD and the design of DBD device for effective operation and applications.

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

    Science.gov (United States)

    Klimov, A S; Medovnik, A V; Tyunkov, A V; Savkin, K P; Shandrikov, M V; Vizir, A V

    2013-01-01

    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. PMID:23387642

  2. Non-thermal plasma reactor with back corona discharge electrode

    Energy Technology Data Exchange (ETDEWEB)

    Czapka, T; Kacprzyk, R, E-mail: tomasz.czapka@pwr.wroc.pl [Institute of electrical Engineering Fundamentals, Wroclaw University of Technology, Wyb. Wyspianskiego 27, 50370 Wroclaw (Poland)

    2011-06-23

    The new design of plasma reactor with back discharge electrode is presented and characterized. The laboratory scale plasma reactor was constructed in a plane parallel geometry with a gas permeable low-field electrode system. The low-field electrode was covered with a dielectric layer enabling the appearance of back corona discharges. The total volume of the reactor is equal to 2 dm{sup 3}.The discharge properties of the reactor operating at dc voltage in air under normal conditions are given. The results of optimizing the electrical properties are also presented. The influence of back discharges on the discharge current is discussed. The maximum discharge current density obtained during the experiment was equal to about 25 {mu}A/cm{sup 2}.

  3. Non-thermal plasma reactor with back corona discharge electrode

    International Nuclear Information System (INIS)

    The new design of plasma reactor with back discharge electrode is presented and characterized. The laboratory scale plasma reactor was constructed in a plane parallel geometry with a gas permeable low-field electrode system. The low-field electrode was covered with a dielectric layer enabling the appearance of back corona discharges. The total volume of the reactor is equal to 2 dm3.The discharge properties of the reactor operating at dc voltage in air under normal conditions are given. The results of optimizing the electrical properties are also presented. The influence of back discharges on the discharge current is discussed. The maximum discharge current density obtained during the experiment was equal to about 25 μA/cm2.

  4. 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.

  5. Performance of Ca{sub 1-x}Sr{sub x}TiO{sub 3} as barriers in dielectric barrier discharges with different Sr content

    Energy Technology Data Exchange (ETDEWEB)

    Li Ruixing; Tang Qing; Yin Shu; Sato Tsugio [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)

    2007-09-07

    Plasma assisted catalytic technology, which uses synergetic technologies between the catalyst and plasma, has attracted much attention over the past several years. Theoretically, permittivity of a dielectric barrier influences the transferred charge of a microdischarge; thus high permittivity can improve the plasma reaction in a dielectric barrier discharge (DBD) plasma reactor. Despite the increased interest in the chemical processes, very little has been reported concerning the influence of materials of a dielectric barrier on DBD plasma reactions, since a high permittivity barrier generally exhibits low fracture strength and low dielectric strength making it break down under strong current pulses. In the present study, Ca{sub 1-x}Sr{sub x}TiO{sub 3} (0.1 {<=} x {<=} 0.4) which possesses a high permittivity and a high fracture strength was prepared by liquid phase sintering and was used as a dielectric barrier for the destruction of carbon dioxide by a DBD plasma reaction. The permittivity of Ca{sub 1-x}Sr{sub x}TiO{sub 3} (0.1 {<=} x {<=} 0.4) increased with increasing SrTiO{sub 3} content; however, the observed CO{sub 2} conversion became greatest using Ca{sub 0.8}Sr{sub 0.2}TiO{sub 3} and then decreased with increasing SrTiO{sub 3} content. These results imply that the reactivity of CO{sub 2} destruction does not monotonously increase with increased permittivity of the Ca{sub 1-x}Sr{sub x}TiO{sub 3} barriers. Both amplitude and density of the current pulses ignited by Ca{sub 0.8}Sr{sub 0.2}TiO{sub 3} were much greater than that of Ca{sub 0.6}Sr{sub 0.4}TiO{sub 3}. Further, it was confirmed that a plasma reaction uniformly proceeded using the Ca{sub 0.8}Sr{sub 0.2}TiO{sub 3} barrier, but proceeded non-uniformly using the Ca{sub 0.6}Sr{sub 0.4}TiO{sub 3} barrier by observing the carbon deposition profiles on the surfaces of the barriers.

  6. Atmospheric air diffuse array-needles dielectric barrier discharge excited by positive, negative, and bipolar nanosecond pulses in large electrode gap

    Science.gov (United States)

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

    2014-09-01

    In this paper, positive, negative, and bipolar nanosecond pulses are employed to generate stable and diffuse discharge plasma using array needles-plate electrode configuration at atmospheric pressure. A comparison study of discharge images, electrical characteristics, optical emission spectra, and plasma vibrational temperature and rotational temperatures in three pulsed polarity discharges is carried on under different discharge conditions. It is found that bipolar pulse is beneficial to the excitation of diffuse dielectric barrier discharge, which can generate a room temperature plasma with more homogeneous and higher discharge intensity compared with unipolar discharges. Under the condition of 6 mm electrode gap distance, 26 kV pulse peak voltage, and 150 Hz pulse repetition rate, the emission intensity of N2 (C3Πu → B3Πg) of the bipolar pulsed discharge is 4 times higher than the unipolar discharge (both positive and negative), while the plasma gas temperature is kept at 300 K, which is about 10-20 K lower than the unipolar discharge plasma.

  7. Numerical description of discharge characteristics of the plasma needle

    OpenAIRE

    Brok, WJM Wouter; Bowden, MD Mark; van Dijk; Mullen, van der, JJAM Joost; Kroesen, GMW Gerrit

    2005-01-01

    The plasma needle is a small atmospheric, nonthermal, radio-frequency discharge, generated at the tip of a needle, which can be used for localized disinfection of biological tissues. Although several experiments have characterized various qualities of the plasma needle, discharge characteristics and electrical properties are still not well known. In order to provide initial estimates on electrical properties and quantities such as particle densities, we employed a two-dimensional, time-depend...

  8. Cold plasma electrochemical reactor with rotary discharge

    International Nuclear Information System (INIS)

    The paper presents a short introduction to gliding discharges technologies and a physical study of a new reactor. This new reactor is used to methane conversion. The aim of the paper is to present a simple flowing model which can be used to determine the voltage waveform of the supply and the influence of the flow on discharge resistance variations. (author)

  9. Electrohydraulic Discharges and Nonthermal Plasma for Water Treatment

    Czech Academy of Sciences Publication Activity Database

    Locke, B.R.; Sato, M.; Hoffman, M.R.; Chang, J.S.; Šunka, Pavel

    2006-01-01

    Roč. 45, č. 1 (2006), s. 882-905. ISSN 0888-5885 Institutional research plan: CEZ:AV0Z20430508 Keywords : Electrical discharges * water cleaning * environmental applications * liquid phase reactor Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.518, year: 2006

  10. AC Glow Discharge Plasma in N2O

    International Nuclear Information System (INIS)

    This paper considers the optical and electrical characterization of AC glow discharge plasma in the abnormal glow mode used for optical emission spectroscopy. The total discharge current and applied voltage are measured using conventional techniques. The electrical characteristics of the planer-cathode glow discharge confirmed that the plasma is operating at abnormal discharge mode characterized by the increases in the operating voltage as the current was raised under given pressure. Optical emission spectroscopy was used to determine the main emission lines of the glow discharge plasma of N2O at pressures between 0.5 and 4.0 Torr. It shows that the discharge emission range is mainly within 300-400 nm. The emission lines correspond to NO, O2, and O2+ are the dominant lines in the glow discharge plasma in the present study. Intensity of the emission lines show linear increase with the discharge current up to 0.4 A followed by saturation at higher currents. No emission lines were observed in this work corresponding to atomic oxygen or nitrogen

  11. Influence of dust particles on rf-discharge plasma afterglow

    International Nuclear Information System (INIS)

    In this paper we report about results of computer simulation by PIC/MCC method of the discharging of dust particles in the plasma afterglow and time dependence of plasma parameters in discharge gap after switching off the voltage. It is shown that discharging of dust particles in the afterglow plasma after switching off voltage of radiofrequency discharge occurs faster in the central part of the electrode gap due to the ion cloud forming and intense recombination of electrons in collisions with dust particles in this area. Moreover, the discharging rate is increasing with increasing of the dust particles density. In the initial stage after the switching off the voltage plasma has a positive potential relative to the electrodes. Eventually, when the electron and ion densities are significantly reduced, the charge of the plasma is determined by the amount of negative dust particles. In this case, the plasma potential is negative relative to the electrodes, which contributes to the effective diffusion of dust particles on the walls of the discharge chamber

  12. Atomic oxygen dynamics in an air dielectric barrier discharge: a combined diagnostic and modeling approach

    Science.gov (United States)

    Baldus, Sabrina; Schröder, Daniel; Bibinov, Nikita; Schulz-von der Gathen, Volker; Awakowicz, Peter

    2015-06-01

    Cold atmospheric pressure plasmas are a promising alternative therapy for treatment of chronic wounds, as they have already shown in clinical trials. In this study an air dielectric barrier discharge (DBD) developed for therapeutic use in dermatology is characterized with respect to the plasma produced reactive oxygen species, namely atomic oxygen and ozone, which are known to be of great importance to wound healing. To understand the plasma chemistry of the applied DBD, xenon-calibrated two-photon laser-induced fluorescence spectroscopy and optical absorption spectroscopy are applied. The measured spatial distributions are shown and compared to each other. A model of the afterglow chemistry based on optical emission spectroscopy is developed to cross-check the measurement results and obtain insight into the dynamics of the considered reactive oxygen species. The atomic oxygen density is found to be located mostly between the electrodes with a maximum density of {{n}\\text{O}}=6× {{10}16} cm-3 . Time resolved measurements reveal a constant atomic oxygen density between two high voltage pulses. The ozone is measured up to 3 mm outside the active plasma volume, reaching a maximum value of {{n}{{\\text{O}3}}}=3× {{10}16} cm-3 between the electrodes.

  13. Intracellular electric fields produced by dielectric barrier discharge treatment of skin

    International Nuclear Information System (INIS)

    The application of atmospheric pressure plasmas to human tissue has been shown to have therapeutic effects for wound healing and in treatment of skin diseases. These effects are attributed to both production of beneficial radicals which intersect with biological reaction chains and to the surface and intracellular generation of electric fields. In this paper, we report on computational studies of the intersection of plasma streamers in atmospheric pressure dielectric barrier discharges (DBDs) sustained in air with human skin tissue, with emphasis on the intracellular generation of electric fields. Intracellular structures and their electrical properties were incorporated into the computational mesh in order to self-consistently couple gas phase plasma transport with the charging of the surface of the skin and the intracellular production of electrical currents. The short duration of a single plasma filament in DBDs and its intersection with skin enables the intracellular penetration of electric fields. The magnitude of these electric fields can reach 100 kV cm-1 which may exceed the threshold for electroporation.

  14. Intracellular electric fields produced by dielectric barrier discharge treatment of skin

    Science.gov (United States)

    Babaeva, Natalia Yu; Kushner, Mark J.

    2010-05-01

    The application of atmospheric pressure plasmas to human tissue has been shown to have therapeutic effects for wound healing and in treatment of skin diseases. These effects are attributed to both production of beneficial radicals which intersect with biological reaction chains and to the surface and intracellular generation of electric fields. In this paper, we report on computational studies of the intersection of plasma streamers in atmospheric pressure dielectric barrier discharges (DBDs) sustained in air with human skin tissue, with emphasis on the intracellular generation of electric fields. Intracellular structures and their electrical properties were incorporated into the computational mesh in order to self-consistently couple gas phase plasma transport with the charging of the surface of the skin and the intracellular production of electrical currents. The short duration of a single plasma filament in DBDs and its intersection with skin enables the intracellular penetration of electric fields. The magnitude of these electric fields can reach 100 kV cm-1 which may exceed the threshold for electroporation.

  15. Intracellular electric fields produced by dielectric barrier discharge treatment of skin

    Energy Technology Data Exchange (ETDEWEB)

    Babaeva, Natalia Yu; Kushner, Mark J, E-mail: nbabaeva@umich.ed, E-mail: mjkush@umich.ed [University of Michigan, Department of Electrical Engineering and Computer Science, 1301 Beal Ave., Ann Arbor, MI 48109 (United States)

    2010-05-12

    The application of atmospheric pressure plasmas to human tissue has been shown to have therapeutic effects for wound healing and in treatment of skin diseases. These effects are attributed to both production of beneficial radicals which intersect with biological reaction chains and to the surface and intracellular generation of electric fields. In this paper, we report on computational studies of the intersection of plasma streamers in atmospheric pressure dielectric barrier discharges (DBDs) sustained in air with human skin tissue, with emphasis on the intracellular generation of electric fields. Intracellular structures and their electrical properties were incorporated into the computational mesh in order to self-consistently couple gas phase plasma transport with the charging of the surface of the skin and the intracellular production of electrical currents. The short duration of a single plasma filament in DBDs and its intersection with skin enables the intracellular penetration of electric fields. The magnitude of these electric fields can reach 100 kV cm{sup -1} which may exceed the threshold for electroporation.

  16. 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. PMID:27404121

  17. Preparation of hydrophobic coating on glass surface by dielectric barrier discharge using a 16 kHz power supply

    International Nuclear Information System (INIS)

    A 16 kHz power supply was used to investigate the preparation of hydrophobic film on glass surface by means of atmospheric pressure dielectric barrier discharge (DBD). Air nonthermal plasma was induced between the two parallel electrodes with a glass plate as dielectric barrier. The process for hydrophobic film includes two parts: one is plasma pretreatment to produce active layer on glass surface, another is to form hydrophobic film on glass surface by means of the interaction between air plasma and polydimethylsiloxane oil. The surface changes were observed using contact angle measurement and atomic force microscope. The results show DBD can increase surface roughness, and effectively improve glass surface activation and form a hydrophobic coating on glass surface, and it is possibility to prepare hydrophobic glass with middle frequency power supply

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

    OpenAIRE

    Liu, Chong; Chernets, Ivan; 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 g...

  19. Formation of white-eye pattern with microdischarge in an air dielectric barrier discharge system

    OpenAIRE

    He, Yafeng; Dong, Lifang; Liu, Weili; Wang, Hongfang; Zhao, Zengchao; FAN, WEILI

    2011-01-01

    We report on the first observation of white-eye pattern in an air dielectric barrier discharge. The patterned discharges undergo a development as following: random spots - quasihexagonal pattern - hexagonal pattern (type I) - hexagonal pattern (type II) - white-eye pattern - chaos as the voltage is increased. The spatiotemporal characteristics of patterned discharges are investigated by using an optical method. Results show that the two discharge modes, uniform mode and filamentary mode, are ...

  20. Discoloration of Congo Red by Rod-Plate Dielectric Barrier Discharge Processes at Atmospheric Pressure

    Science.gov (United States)

    Wu, Haixia; Fang, Zhi; Zhou, Tong; Lu, Chen; Xu, Yanhua

    2016-05-01

    A dielectric barrier discharge (DBD) reactor with a rod-plate electrode configuration was used for the oxidative decomposition of Congo red dye in an aqueous solution. Plasma was generated in the gas space above the water interface under atmospheric pressure. Discharge characteristics were analyzed by voltage-current waveforms. Effects of applied voltage, initial conductivity, and initial concentration were also analyzed. Congo red discoloration increased with increased applied voltage and decreased conductivity. The initial conductivity significantly influenced the Congo red discoloration. Under the same conditions, the highest discoloration rate was obtained at 25 mg/L. The presence of ferrous ions in the solutions had a substantial positive effect on Fenton dye degradation and flocculation. At an applied voltage of 20 kV, about 100% of dye was degraded after 4 min of Fe2+/DBD treatment. Results showed that adding a certain dosage of hydrogen peroxide to the wastewater could enhance the discoloration rate. Possible pathways of Congo red discoloration by DBD plasma were proposed based on GC/MS, FTIR, and UV-vis spectroscopy analyses. supported by National Natural Science Foundation of China (No. 51377075), the Natural Science Foundation of Jiangsu Province of China (Nos. BK20131412, BK20150951)

  1. Removal of atrazine in water by combination of activated carbon and dielectric barrier discharge.

    Science.gov (United States)

    Vanraes, Patrick; Willems, Gert; Nikiforov, Anton; Surmont, Pieter; Lynen, Frederic; Vandamme, Jeroen; Van Durme, Jim; Verheust, Yannick P; Van Hulle, Stijn W H; Dumoulin, Ann; Leys, Christophe

    2015-12-15

    Efficiency of modern wastewater treatment plants to remove or decompose persistent contaminants in low concentration is often insufficient to meet the demands imposed by governmental laws. Novel, efficient and cheap methods are required to address this global issue. We developed a new type of plasma reactor, in which atrazine decomposition by atmospheric dielectric barrier discharge (DBD) in dry air is combined with micropollutant adsorption on activated carbon textile and with extra bubbling of generated ozone. Investigation of reaction kinetics and by-product analysis shows that increasing input power with a factor 3.5 leads to deeper atrazine oxidation without significantly changing energy yield of atrazine removal. By-products of first and later generations are detected with HPLC-MS analysis in water and adsorbed on the activated carbon textile. Our reactor is compared in energy efficiency with reactors described in literature, showing that combination of plasma discharge with pollutant adsorption and ozone recycling is attractive for future applications of water treatment. PMID:26282086

  2. Quantitative characterization of a dielectric barrier discharge in air applying non-calibrated spectrometer, current measurement and numerical simulation

    International Nuclear Information System (INIS)

    A non-calibrated spectrometer is used for quantitative characterization of a dielectric barrier discharge (DBD) in air wherein optical emission spectroscopy (OES) is completed by current measurement and numerical simulation. This diagnostic method is applicable when the cross-sectional area of the active plasma volume and the current density can be determined. The nitrogen emission in the spectral range of 330–406 nm is used for OES diagnostics. The electric field in the active plasma volume is determined by applying the measured spectrum, well-known Franck–Condon factors for nitrogen transitions and numerically simulated electron distribution functions. The measured electric current density is used for the determination of electron density in plasma. Using the determined plasma parameters, the dissociation rates of nitrogen and oxygen in active plasma volume are calculated, which can be used for the simulation of chemical kinetics. (paper)

  3. Reduction of aerodynamic friction drag of moving bodies using a Microwave-Dielectric-Barrier-Discharge actuator controlling the boundary layer

    Science.gov (United States)

    Pierre, Thiery

    2015-11-01

    A new plasma device named M-DBD (Microwave Dielectric Barrier Discharge) is used for controlling the boundary layer in order to reduce the drag force. A compact resonant UHF structure comprising a resonant element in the form of a quarter-wave antenna creates a mini-plasma insulated from the UHF electrodes by mica sheets. Additional electrodes induce an electric field in the plasma and transiently move the ions of the plasma. The high collision rate with the neutral molecules induce the global transient flow of the neutral gas. The temporal variation of the applied electric field is chosen in order to obtain a modification of the local boundary layer. First tests using an array of M-DBD plasma actuators are underway (see Patent ref. WO 2014111469 A1).

  4. Comparison of dielectric barrier discharge, atmospheric pressure radiofrequency-driven glow discharge and direct analysis in real time sources for ambient mass spectrometry of acetaminophen

    Energy Technology Data Exchange (ETDEWEB)

    Kratzer, Jan [Institute for National Measurement Standards, National Research Council of Canada, 1200 Montreal Road, Ottawa, Ontario, K1A 0R6 (Canada); Institute of Analytical Chemistry of the ASCR, v.v.i., Veveri 97, CZ-602 00 Brno (Czech Republic); Mester, Zoltan [Institute for National Measurement Standards, National Research Council of Canada, 1200 Montreal Road, Ottawa, Ontario, K1A 0R6 (Canada); Sturgeon, Ralph E., E-mail: Ralph.Sturgeon@nrc-cnrc.gc.ca [Institute for National Measurement Standards, National Research Council of Canada, 1200 Montreal Road, Ottawa, Ontario, K1A 0R6 (Canada)

    2011-08-15

    Three plasma-based ambient pressure ion sources were investigated; laboratory constructed dielectric barrier and rf glow discharges, as well as a commercial corona discharge (DART source). All were used to desorb and ionize a model analyte, providing sampling techniques for ambient mass spectrometry (MS). Experimental parameters were optimized to achive highest signal for acetaminophen as the analyte. Insight into the mechanisms of analyte desorption and ionization was obtained by means of emission spectrometry and ion current measurements. Desorption and ionization mechanisms for this analyte appear to be identical for all three plasma sources. Emission spectra differ only in the intensities of various lines and bands. Desorption of solid analyte requires transfer of thermal energy from the plasma source to sample surface, in the absence of which complete loss of MS response occurs. For acetaminophen, helium was the best plasma gas, providing 100- to 1000-fold higher analyte response than with argon or nitrogen. The same trend was also evident with background ions (protonated water clusters). MS analyte signal intensity correlates with the ion density (expressed as ion current) in the plasma plume and with emission intensity from excited state species in the plasma. These observations support an ionization process which occurs via proton transfer from protonated water clusters to analyte molecules.

  5. Comparison of dielectric barrier discharge, atmospheric pressure radiofrequency-driven glow discharge and direct analysis in real time sources for ambient mass spectrometry of acetaminophen

    International Nuclear Information System (INIS)

    Three plasma-based ambient pressure ion sources were investigated; laboratory constructed dielectric barrier and rf glow discharges, as well as a commercial corona discharge (DART source). All were used to desorb and ionize a model analyte, providing sampling techniques for ambient mass spectrometry (MS). Experimental parameters were optimized to achive highest signal for acetaminophen as the analyte. Insight into the mechanisms of analyte desorption and ionization was obtained by means of emission spectrometry and ion current measurements. Desorption and ionization mechanisms for this analyte appear to be identical for all three plasma sources. Emission spectra differ only in the intensities of various lines and bands. Desorption of solid analyte requires transfer of thermal energy from the plasma source to sample surface, in the absence of which complete loss of MS response occurs. For acetaminophen, helium was the best plasma gas, providing 100- to 1000-fold higher analyte response than with argon or nitrogen. The same trend was also evident with background ions (protonated water clusters). MS analyte signal intensity correlates with the ion density (expressed as ion current) in the plasma plume and with emission intensity from excited state species in the plasma. These observations support an ionization process which occurs via proton transfer from protonated water clusters to analyte molecules.

  6. Comparison of dielectric barrier discharge, atmospheric pressure radiofrequency-driven glow discharge and direct analysis in real time sources for ambient mass spectrometry of acetaminophen

    Science.gov (United States)

    Kratzer, Jan; Mester, Zoltán; Sturgeon, Ralph E.

    2011-08-01

    Three plasma-based ambient pressure ion sources were investigated; laboratory constructed dielectric barrier and rf glow discharges, as well as a commercial corona discharge (DART source). All were used to desorb and ionize a model analyte, providing sampling techniques for ambient mass spectrometry (MS). Experimental parameters were optimized to achive highest signal for acetaminophen as the analyte. Insight into the mechanisms of analyte desorption and ionization was obtained by means of emission spectrometry and ion current measurements. Desorption and ionization mechanisms for this analyte appear to be identical for all three plasma sources. Emission spectra differ only in the intensities of various lines and bands. Desorption of solid analyte requires transfer of thermal energy from the plasma source to sample surface, in the absence of which complete loss of MS response occurs. For acetaminophen, helium was the best plasma gas, providing 100- to 1000-fold higher analyte response than with argon or nitrogen. The same trend was also evident with background ions (protonated water clusters). MS analyte signal intensity correlates with the ion density (expressed as ion current) in the plasma plume and with emission intensity from excited state species in the plasma. These observations support an ionization process which occurs via proton transfer from protonated water clusters to analyte molecules.

  7. Prediction of atmospheric pressure glow discharge in dielectric-barrier system

    Science.gov (United States)

    Duan, Xiaoxi; He, Feng; Ouyang, Jiting

    2010-06-01

    A one-dimensional fluid model was used to investigate the breakdown mechanism and discharge mode in dielectric-barrier system. The results show that the dielectric barrier discharge mode depends strongly on the gas property (i.e., the electron multiplication). The atmospheric pressure dielectric barrier glow discharge could only be achieved in a gas (e.g., noble gas) in which the first Townsend ionization coefficient is sufficiently small and the electron multiplication does not rise up rapidly with the electric field, while could not be sustained in the gas (e.g., N2 and O2) in which the electron multiplication is sensitive to the field.

  8. 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.

  9. Experimental study of hydrogen plasma reforming by intermittent spark discharges

    International Nuclear Information System (INIS)

    We present an experimental analysis of an air/methane high-voltage discharge at atmospheric pressure which operates in an intermittent spark regime. The aim is to study the feasibility of hydrogen reforming through plasma processing. The structure of the spark and the electrical characteristics of the discharge were studied as a function of the air/methane mixture composition, the gas flow rate, the average current, and the external circuitry resistance. Discharge spectra in the visible and near-ultraviolet range show the production of several radicals and excited species which provide a clue to the relevant chemical kinetics in the plasma state. Detailed mass analysis of the composition of the exhaust gas flow shows a significant production of hydrogen and high conversion efficiency of methane. The dependence on the discharge operating parameters was investigated in order to clarify the optimal setup design for an efficient plasma reformer

  10. Generation of pulsed discharge plasma in water with fine bubbles

    Science.gov (United States)

    Hayashi, Yui; Takada, Noriharu; Kanda, Hideki; Goto, Motonobu; Goto laboratory Team

    2015-09-01

    Recently, some researchers have proposed electric discharge methods with bubbles in water because the discharge plasma inside bubble was easy to be generated compared to that in water. Almost all of these methods introduced bubbles in the order of millimeter size from a nozzle placed in water. In these methods, bubbles rose one after another owing to high rising speed of millibubble, leading to inefficient gas consumption. We proposed fine bubbles introduction at the discharge area in water. A fine bubble is determined a bubble with less than 100 μm in a diameter. Fine bubbles exhibit extremely slow rising speed. Fine bubbles decrease in size during bubble rising and subsequently collapse in water with OH radical generation. Therefore, combining the discharge plasma with fine bubbles is expected to generate more active species with small amount of gas consumption. In this work, fine bubbles were introduced in water and pulsed discharge plasma was generated between two cylindrical electrodes which placed in water. We examined effects of fine bubbles on electric discharge in water when argon or oxygen gas was utilized as feed gas. Fine bubbles enhanced optical emission of hydrogen and oxygen atoms from H2O molecules, but that of feed gas was not observed. The formation mechanism of H2O2 by electric discharge was supposed to be different from that with no bubbling. Dissolved oxygen in water played a role in H2O2 formation by the discharge with fine bubbles.

  11. Radiation profile measurements for edge transport barrier discharges in Compact Helical System using AXUV photodiode arrays

    International Nuclear Information System (INIS)

    The formation of edge transport barrier (ETB) has recently been found in Compact Helical System (CHS) plasmas heated by co-injected neutral beam injection (NBI) with strong gas puffing. This regime is characterized by the appearance of the steep gradient of the electron density near the edge following the abrupt drop of hydrogen Balmer alpha (Hα) line intensity. In addition to single channel pyroelectric detector as a conventional bolometer, we have employed unfiltered absolute extreme ultraviolet (AXUV) photodiode arrays as a simple and low-cost diagnostic to investigate spatial and temporal variations of radiation emissivity in the ETB discharges. A compact mounting module for a 20 channel AXUV photodiode array including an in-vacuum preamplifier for immediate current-voltage conversion has successfully been designed and fabricated. Two identical modules installed in the upper and lower viewports provide 40 lines of sight covering the inboard and outboard sides within the horizontally elongated cross section of the CHS plasma with wide viewing angle. Although spectral uniformity of the detector sensitivity of the AXUV photodiode is unsatisfied for photon energies lower than 200 eV, it has been confirmed that the signals of AXUV photodiode and pyroelectric detector in the ETB discharges show roughly the same behavior except for the very beginning and end of the discharges. The results of the measurements in typical ETB discharges show that the signals of all the channels of the AXUV photodiode arrays begin to increase more rapidly at the moment of the transition than before. The rate of the increase is larger for the edge viewing chords than for the center viewing ones, which indicates the flattening of the radiation profile following the change in the electron density profile after the formation of the ETB. However, the signals for the edge chords tend to saturate after several tens of milliseconds, while they still continue to increase for the central chords

  12. The Key Factor for Uniform and Patterned Glow Dielectric Barrier Discharge

    Institute of Scientific and Technical Information of China (English)

    OUYANG Ji-Ting; DUAN Xiao-Xi; XU Shao-Wei; HE Feng

    2012-01-01

    We present the results from 2D fluid modeling of the key roles controlling the glow dielectric barrier discharge (DBD) structure. A uniform DBD can be sustained at lower frequency when the space charge reaches uniformity due to plasma decay, while the patterned structure appears above a critical frequency when the space charge is nonuniform. The patterns start from the electrode edge where the electric field is significantly distorted, characterized by the patterned seed electrons that always form ahead of the surface charges. The formation of the patterned DBD structure is associated with the lateral inhibition of the local increase of space charges. The distribution of the volume seed electrons plays a key role in the DBD structure while the distribution of surface charge is a result of the formed structure.%We present the results from 2D fluid modeling of the key roles controlling the glow dielectric barrier discharge (DBD) structure.A uniform DBD can be sustained at lower frequency when the space charge reaches uniformity due to plasma decay,while the patterned structure appears above a critical frequency when the space charge is nonuniform.The patterns start from the electrode edge where the electric field is significantly distorted,characterized by the patterned seed electrons that always form ahead of the surface charges.The formation of the patterned DBD structure is associated with the lateral inhibition of the local increase of space charges.The distribution of the volume seed electrons plays a key role in the DBD structure while the distribution of surface charge is a result of the formed structure.

  13. Effect of a direct current bias on the electrohydrodynamic performance of a surface dielectric barrier discharge actuator for airflow control

    Science.gov (United States)

    Yan, Huijie; Yang, Liang; Qi, Xiaohua; Ren, Chunsheng

    2015-02-01

    The effect of a DC bias on the electrohydrodynamics (EHD) force induced by a surface dielectric barrier AC discharge actuator for airflow control at the atmospheric pressure is investigated. The measurement of the surface potential due to charge deposition at different DC biases is carried out by using a special designed corona like discharge potential probe. From the surface potential data, the plasma electromotive force is shown not affected much by the DC biases except for some reduction of the DC bias near the exposed electrode edge for the sheath-like configuration. The total thrust is measured by an analytical balance, and an almost linear relationship to the potential voltage at the exposed electrode edge is found for the direct thrust force. The temporally averaged ionic wind characteristics are investigated by Pitot tube sensor and schlieren visualization system. It is found that the ionic wind velocity profiles with different DC biases are almost the same in the AC discharge plasma area but gradually diversified in the further downstream area as well as the upper space away from the discharge plasma area. Also, the DC bias can significantly modify the topology of the ionic wind produced by the AC discharge actuator. These results can provide an insight into how the DC biases to affect the force generation.

  14. Adhesion enhancement by a dielectric barrier discharge of PDMS used for flexible and stretchable electronics

    International Nuclear Information System (INIS)

    Currently, there is a strong tendency to replace rigid electronic assemblies by mechanically flexible and stretchable equivalents. This emerging technology can be applied for biomedical electronics, such as implantable devices and electronics on skin. In the first step of the production process of stretchable electronics, electronic interconnections and components are encapsulated into a thin layer of polydimethylsiloxane (PDMS). Afterwards, the electronic structures are completely embedded by placing another PDMS layer on top. It is very important that the metals inside the electronic circuit do not leak out in order to obtain a highly biocompatible system. Therefore, an excellent adhesion between the 2 PDMS layers is of great importance. However, PDMS has a very low surface energy, resulting in poor adhesion properties. Therefore, in this paper, PDMS films are plasma treated with a dielectric barrier discharge (DBD) operating in air at medium pressure (5.0 kPa). Contact angle and XPS measurements reveal that plasma treatment increases the hydrophilicity of the PDMS films due to the incorporation of silanol groups at the expense of methyl groups. T-peel tests show that plasma treatment rapidly imparts adhesion enhancement, but only when both PDMS layers are plasma treated. Results also reveal that it is very important to bond the plasma-treated PDMS films immediately after treatment. In this case, an excellent adhesion is maintained several days after treatment. The ageing behaviour of the plasma-treated PDMS films is also studied in detail: contact angle measurements show that the contact angle increases during storage in air and angle-resolved XPS reveals that this hydrophobic recovery is due to the migration of low molar mass PDMS species to the surface

  15. Investigation of nanosecond pulse dielectric barrier discharges in still air and in transonic flow by optical methods

    Science.gov (United States)

    Peschke, P.; Goekce, S.; Leyland, P.; Ott, P.

    2016-01-01

    In the present study the interaction of nanosecond pulsed dielectric barrier discharge (ns-DBD) actuators with aerodynamic flow up to transonic velocities was investigated. The primary focus was on the influence of the flow on the discharge and the effects of the discharge itself. In addition, the influence of the ns-DBD on a shock-wave was studied. The aim was to improve the understanding of the plasma-flow interaction, a topic that is not yet fully understood, in particular for ns-DBD. The actuator was integrated in two different models, a NACA 3506 compressor blade profile and a bump geometry at the bottom of the wind tunnel. The effect of the rapid energy deposition close to the discharge was examined with the phase-locked schlieren visualisation technique. Images of the plasma acquired with short exposure times revealed information on the discharge evolution. The results show a significant effect of the flow on the discharge characteristics, in particular due to the drop of static pressure. On the other hand, no significant effect of the ns-DBD on the flow was observed due to unfavourable flow conditions, which underlines the importance of the actuator’s placement.

  16. Study of discharge in quiescent plasma machine of the INPE

    International Nuclear Information System (INIS)

    Measurements of principal plasma parameters produced by quiescent plasma machine of the Instituto de Pesquisas Espaciais (INPE) for current of 500 mA and several values of pressure and discharge power are presented. A qualitative interpretation for obtained results is done and a simple model for plasma density is compared with experimental values. The conditions of cathode operation are also investigated. (M.C.K.)

  17. Reproducing continuous radio blackout using glow discharge plasma

    International Nuclear Information System (INIS)

    A novel plasma generator is described that offers large-scale, continuous, non-magnetized plasma with a 30-cm-diameter hollow structure, which provides a path for an electromagnetic wave. The plasma is excited by a low-pressure glow discharge, with varying electron densities ranging from 109 to 2.5 × 1011 cm−3. An electromagnetic wave propagation experiment reproduced a continuous radio blackout in UHF-, L-, and S-bands. The results are consistent with theoretical expectations. The proposed method is suitable in simulating a plasma sheath, and in researching communications, navigation, electromagnetic mitigations, and antenna compensation in plasma sheaths

  18. Plasma Structure and Behavior of Miniature Ring-Cusp Discharges

    Science.gov (United States)

    Mao, Hann-Shin

    Miniature ring-cusp ion thrusters provide a unique blend of high efficiencies and millinewton level thrust for future spacecraft. These thrusters are attractive as a primary propulsion for small satellites that require a high delta V, and as a secondary propulsion for larger spacecraft that require precision formation flying, disturbance rejection, or attitude control. To ensure desirable performance throughout the life of such missions, an advancement in the understanding of the plasma structure and behavior of miniature ring-cusp discharges is required. A research model was fabricated to provide a simplified experimental test bed for the analysis of the plasma discharge chamber of a miniature ion thruster. The plasma source allowed for spatially resolved measurements with a Langmuir probe along a meridian plane. Probe measurements yielded plasma density, electron temperature, and plasma potential data. The magnetic field strength was varied along with the discharge current to determine the plasma behavior under various conditions. The structure of the plasma properties were found to be independent of the discharge power under the proper scaling. It was concluded that weaker magnetic fields can improve the overall performance for ion thruster operation. To further analyze the experimental measurements, a framework was developed based on the magnetic field. A flux aligned coordinate system was developed to decouple the perpendicular and parallel plasma motion with respect to the magnetic field. This was done using the stream function and magnetic scalar potential. Magnetic formulae provided intuition on the field profiles dependence on magnet dimensions. The flux aligned coordinate system showed that the plasma was isopycnic along constant stream function values. This was used to develop an empirical relation suitable for estimating the spatial behavior and to determine the plasma volume and loss areas. The plasma geometry estimates were applied to a control volume

  19. CO2 Dissociation using the Versatile Atmospheric Dielectric Barrier Discharge Experiment (VADER)

    Science.gov (United States)

    Lindon, Michael Allen

    As of 2013, the Carbon Dioxide Information Analysis Center (CDIAC) estimates that the world emits approximately 36 trillion metric tons of Carbon Dioxide (CO2) into the atmosphere every year. These large emissions have been correlated to global warming trends that have many consequences across the globe, including glacial retraction, ocean acidification and increased severity of weather events. With green technologies still in the infancy stage, it can be expected that CO2 emissions will stay this way for along time to come. Approximately 41% of the emissions are due to electricity production, which pump out condensed forms of CO2. This danger to our world is why research towards new and innovative ways of controlling CO2 emissions from these large sources is necessary. As of now, research is focused on two primary methods of CO2 reduction from condensed CO2 emission sources (like fossil fuel power plants): Carbon Capture and Sequestration (CCS) and Carbon Capture and Utilization (CCU). CCS is the process of collecting CO2 using absorbers or chemicals, extracting the gas from those absorbers and finally pumping the gas into reservoirs. CCU on the other hand, is the process of reacting CO2 to form value added chemicals, which can then be recycled or stored chemically. A Dielectric Barrier discharge (DBD) is a pulsed, low temperature, non-thermal, atmospheric pressure plasma which creates high energy electrons suitable for dissociating CO2 into its components (CO and O) as one step in the CCU process. Here I discuss the viability of using a DBD for CO2 dissociation on an industrial scale as well as the fundamental physics and chemistry of a DBD for CO2 dissociation. This work involved modeling the DBD discharge and chemistry, which showed that there are specific chemical pathways and plasma parameters that can be adjusted to improve the CO2 reaction efficiencies and rates. Experimental studies using the Versatile Atmospheric dielectric barrier Discharge Expe

  20. 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. PMID:24464536

  1. A Radical-Mediated Pathway for the Formation of [M + H]+ in Dielectric Barrier Discharge Ionization

    Science.gov (United States)

    Wolf, Jan-Christoph; Gyr, Luzia; Mirabelli, Mario F.; Schaer, Martin; Siegenthaler, Peter; Zenobi, Renato

    2016-09-01

    Active capillary plasma ionization is a highly efficient ambient ionization method. Its general principle of ion formation is closely related to atmospheric pressure chemical ionization (APCI). The method is based on dielectric barrier discharge ionization (DBDI), and can be constructed in the form of a direct flow-through interface to a mass spectrometer. Protonated species ([M + H]+) are predominantly formed, although in some cases radical cations are also observed. We investigated the underlying ionization mechanisms and reaction pathways for the formation of protonated analyte ([M + H]+). We found that ionization occurs in the presence and in the absence of water vapor. Therefore, the mechanism cannot exclusively rely on hydronium clusters, as generally accepted for APCI. Based on isotope labeling experiments, protons were shown to originate from various solvents (other than water) and, to a minor extent, from gaseous impurities and/or self-protonation. By using CO2 instead of air or N2 as plasma gas, additional species like [M + OH]+ and [M - H]+ were observed. These gas-phase reaction products of CO2 with the analyte (tertiary amines) indicate the presence of a radical-mediated ionization pathway, which proceeds by direct reaction of the ionized plasma gas with the analyte. The proposed reaction pathway is supported with density functional theory (DFT) calculations. These findings add a new ionization pathway leading to the protonated species to those currently known for APCI.

  2. Decolorization of reactive black 5 using dielectric barrier discharge in the presence of inorganic salts

    Directory of Open Access Journals (Sweden)

    Dojčinović Biljana P.

    2012-01-01

    Full Text Available Inorganic salts improve the coloration of textiles, which increase pollution load on dyehouse effluent in general. Decolorization of reactive textile dye C.I. Reactive Black 5 was studied using Advanced Oxidation Processes (AOPs in a non-thermal plasma reactor, based on coaxial water falling film Dielectric Barrier Discharge (DBD. Initial dye concentration in the solution was 40.0 mg L-1. The effects of addition of inorganic salt different high concentrations (NaCl, Na2SO4 and Na2CO3 on the degree of decolorization were studied. Recirculation of dye solution through the DBD reactor with applied energy density 45-315 kJ L-1 was used. The influence of residence time was investigated after 5 minutes and 24 hours of plasma treatment. Decolorization of the dyes was monitored by spectrophotometric measurement. Changes of pH values and the conductivity of dye solution after each recirculation were tested. The most effective decolorization of over 90% was obtained with the addition of NaCl (50 g L-1, applied energy density of 135 kJ L-1 and after residence time of 24 hours of plasma treatment. Decolorization of solutions containing inorganic salts Na2SO4 and Na2CO3 were lower than for the solution without salt.

  3. Effects of hydrocarbon contamination on ozone generation with dielectric barrier discharges

    Science.gov (United States)

    Lopez, Jose L.; Vezzu, Guido; Freilich, Alfred; Paolini, Bernhard

    2013-08-01

    The increasing usage of the feed gases of lower grade liquid oxygen (LOX) containing higher levels of trace hydrocarbon impurities in dielectric barrier discharge (DBD) for ozone generation requires a better understanding of the kinetics of the by-product formation resulting from reactions involving these hydrocarbon impurities. As a case study of hydrocarbon impurities, the kinetics of CH4 conversion in DBDs and the subsequent HNO3 formation were investigated by means of gas-phase plasma diagnostics, supported by detailed process modeling, and extensive in-situ and ex-situ by-product analysis. The by-products formation in the plasma with the presence of CH4, were found to differ significantly in oxygen-fed generators as compared to generators fed with oxygen/nitrogen mixtures. The amount of HNO3 formed depends on the concentration of NOx formed in the plasma and the amount of CH4 that is converted, but not on the O3 concentration. In the present work we have investigated CH4 concentrations of up to 1.95 wt% of the feed gas. The rate of deterioration of the overall ozone generator performance was found to be affected by the concentration of nitrogen in the oxygen/nitrogen mixture.

  4. Improving Hydrophobicity of Glass Surface Using Dielectric Barrier Discharge Treatment in Atmospheric Air

    International Nuclear Information System (INIS)

    Non-thermal plasmas under atmospheric pressure are of great interest in industrial applications, especially in material surface treatment. In this paper, the treatment of a glass surface for improving hydrophobicity using the non-thermal plasma generated by dielectric barrier discharge (DBD) at atmospheric pressure in ambient air is conducted, and the surface properties of the glass before and after the DBD treatment are studied by using contact angle measurement, surface resistance measurement and wet flashover voltage tests. The effects of the applied voltage and time duration of DBD on the surface modification are studied, and the optimal conditions for the treatment are obtained. It is found that a layer of hydrophobic coating is formed on the glass surface after spraying a thin layer of silicone oil and undergoing the DBD treatment, and the improvement of hydrophobicity depends on DBD voltage and treating time. It seems that there exists an optimum treating time for a certain applied voltage of DBD during the surface treatment. The test results of thermal aging and chemical aging show that the hydrophobic layer has quite stable characteristics. The interaction mechanism between the DBD plasma and the glass surface is discussed. It is concluded that CH3 and large molecule radicals can react with the radicals in the glass surface to replace OH, and the hydrophobicity of the glass surface is improved accordingly

  5. Improving Hydrophobicity of Glass Surface Using Dielectric Barrier Discharge Treatment in Atmospheric Air

    Institute of Scientific and Technical Information of China (English)

    FANG Zhi; QIU Yuchang; WANG Hui; E. KUFFEL

    2007-01-01

    Non-thermal plasmas under atmospheric pressure are of great interest in industrial applications, especially in material surface treatment. In this paper, the treatment of a glass surface for improving hydrophobicity using the non-thermal plasma generated by dielectric barrier discharge (DBD) at atmospheric pressure in ambient air is conducted, and the surface properties of the glass before and after the DBD treatment are studied by using contact angle measurement, surface resistance measurement and wet flashover voltage tests. The effects of the applied voltage and time duration of DBD on the surface modification are studied, and the optimal conditions for the treatment are obtained. It is found that a layer of hydrophobic coating is formed on the glass surface after spraying a thin layer of silicone oil and undergoing the DBD treatment, and the improvement of hydrophobicity depends on DBD voltage and treating time. It seems that there exists an optimum treating time for a certain applied voltage of DBD during the surface treatment. The test results of thermal aging and chemical aging show that the hydrophobic layer has quite stable characteristics. The interaction mechanism between the DBD plasma and the glass surface is discussed. It is concluded that CH3 and large molecule radicals can react with the radicals in the glass surface to replace OH, and the hydrophobicity of the glass surface is improved accordingly.

  6. Modelling of atmospheric pressure dielectric barrier discharges with emphasis on stability issues

    International Nuclear Information System (INIS)

    The properties of a barrier discharge in nitrogen near the transition from the Townsend mode to the filamentary mode are studied on the basis of a two-dimensional fluid model. The formation of an intermediate mode (multipeak Townsend discharge) is discussed. The surface processes (ion-electron emission and photoemission) and the positive volume charge are proposed as the mechanisms of formation of a multipeak mode. It is shown that the Townsend mode is stable relative to radial fluctuations, whereas the glow mode is unstable and turns into a filamentary mode. The development of a radial fluctuation into a filament is demonstrated. The homogeneity of the barrier discharge depends on the barrier material. In particular, the widening of the stability region for the discharge with low-permittivity barriers is proved

  7. Modelling of atmospheric pressure dielectric barrier discharges with emphasis on stability issues

    Energy Technology Data Exchange (ETDEWEB)

    Maiorov, V A; Golubovskii, Yu B [Faculty of Physics, St Petersburg State University, Ulianovskaya ul., 1, 198904 Petrodvorets, St Petersburg (Russian Federation)

    2007-02-15

    The properties of a barrier discharge in nitrogen near the transition from the Townsend mode to the filamentary mode are studied on the basis of a two-dimensional fluid model. The formation of an intermediate mode (multipeak Townsend discharge) is discussed. The surface processes (ion-electron emission and photoemission) and the positive volume charge are proposed as the mechanisms of formation of a multipeak mode. It is shown that the Townsend mode is stable relative to radial fluctuations, whereas the glow mode is unstable and turns into a filamentary mode. The development of a radial fluctuation into a filament is demonstrated. The homogeneity of the barrier discharge depends on the barrier material. In particular, the widening of the stability region for the discharge with low-permittivity barriers is proved.

  8. Investigation of plasma armature voltage gradients using a static discharge

    International Nuclear Information System (INIS)

    This paper describes a technique for obtaining voltage scaling parameters by measuring the plasma voltage on small-scale, static discharges. Validity of the static arc measurement is demonstrated by comparing the static arc voltage gradient for copper/G-10 with the muzzle voltages measured on various EML devices with bore diameters ranging from 1 to 10 cm. The experimental discharge chamber resembles a conventional, bolt-together railgun device with a length of 30 cm. The muzzle end is blocked and sealed to contain the plasma pressure. The discharge channel width is 6.35 mm and the discharge height is variable from 6.35 to 25.4 mm in increments of 6.35 mm. Rail width is varied with discharge height to maintain the plasma pressure constant at fixed current. The breech end is open to provide venting of arc ablation products. Both the rail and insulator surface are provided with thin replaceable liners to facilitate rapid clean-up after each test. Careful attention to tolerances combined with polyethylene gaskets and large bolting force are required to provide leak-tight operation. A series of tests has been performed using the most common railgun materials, copper electrodes and G-10 fiberglass insulation. The test current had a peak value of 145 kA (23 kA/mm) and a quarter cycle discharge time of 220 μs. The plasma voltage was measured at the muzzle end using a shunt resistance and a current transformer

  9. A gapless micro-dielectric-barrier-discharge ion source for analytical applications

    CERN Document Server

    Coy, Stephen L; Eiceman, Gary A; Kanik, Isik

    2016-01-01

    Use of dielectric barrier discharge (DBD) as an ion source for sensitive chemical analysis is uncommon because barrier discharges generate excess noise due to spatial and temporal instability. This design uses contacted, crossed glass-coated micro-wires to focus the field into a gradually vanishing gap, suppressing spatial and temporal variability, reducing pressure, temperature, and humidity effects, stabilizing discharge initiation and limiting chemical fragmentation. Positive-ion-mode proton transfer, chemical fragmentation from a micro-discharge, and NO+ adducts combine to allow broad chemical sensitivity. We analyze noise properties of the ion source and report chemical responsivity for a wide range of volatile organic compounds. Source noise spectral density is compared for three systems: the contacted coated wires source, a gapped dielectric barrier discharge source, and a 5 mCi Ni-63 radioactive source. The crossed-wires source shows noise properties approaching those of the white-noise Ni-63 source, ...

  10. Preconcentration and Atomization of Arsane in a Dielectric Barrier Discharge with Detection by Atomic Absorption Spectrometry.

    Science.gov (United States)

    Novák, Petr; Dědina, Jiří; Kratzer, Jan

    2016-06-01

    Atomization of arsane in a 17 W planar quartz dielectric barrier discharge (DBD) atomizer was optimized, and its performance was compared to that of a multiple microflame quartz tube atomizer (MMQTA) for atomic absorption spectrometry (AAS). Argon, at a flow rate of 60 mL min(-1), was the best DBD discharge gas. Free As atoms were also observed in the DBD with nitrogen, hydrogen, and helium discharge gases but not in air. A dryer tube filled with NaOH beads placed downstream from the gas-liquid separator to prevent residual aerosol and moisture transport to the atomizer was found to improve the response by 25%. Analytical figures of merit were comparable, reaching an identical sensitivity of 0.48 s ng (-1) As in both atomizers and limits of detection (LOD) of 0.15 ng mL(-1) As in MMQTA and 0.16 ng mL(-1) As in DBD, respectively. Compared to MMQTA, DBD provided 1 order of magnitude better resistance to interference from other hydride-forming elements (Sb, Se, and Bi). Atomization efficiency in DBD was estimated to be 100% of that reached in the MMQTA. A simple procedure of lossless in situ preconcentration of arsane was developed. Addition of 7 mL min(-1) O2 to the Ar plasma discharge resulted in a quantitative retention of arsane in the optical arm of the DBD atomizer. Complete analyte release and atomization was reached as soon as oxygen was switched off. Preconcentration efficiency of 100% was observed, allowing a decrease of the LOD to 0.01 ng mL(-1) As employing a 300 s preconcentration period. PMID:27159266

  11. AC barrier pin-plane corona: similarities and distinctions to DC positive and negative coronas and dielectric barrier discharge

    International Nuclear Information System (INIS)

    Alternative current (AC) atmospheric pressure corona between the sharpened pin and metallic plane covered with a thin dielectric material is widely used in applications. This kind of discharge can be classified the AC barrier corona (ACBC), because one would expect that ACBC exhibits the properties, which are close to those of both AC dielectric barrier discharge (DBD) and DC (direct current) positive and negative pin-plane coronas. Experimental and numerical study on properties of ACBC in air, nitrogen, Ar, He at atmospheric pressure was carried out. A detailed comparison between ACBC and DC positive and negative pin-plane coronas was made. (author)

  12. Phase resolved cross-correlation spectroscopy on surface barrier discharges in air at atmospheric pressure

    OpenAIRE

    Brandenburg, R; Grosch, H; Hoder, T.; Weltmann, K.-D.

    2011-01-01

    Abstract Microdischarges in a surface barrier discharge with special asymmetric needle-needle arrangement were investigated by means of cross-correlation spectroscopy (with sub-ns and sub-mm resolution) and an intensified CCD camera equipped with a far field microscope. The surface barrier discharge was driven at conditions (overvoltage) resulting in several microdischarges per half period of the applied sinusoidal voltage. At these conditions and in this arrangement regular patter...

  13. Internal Transport Barrier in Edge Plasma of Small Size Divertor Tokamak Using Neutral Beam Injection

    Science.gov (United States)

    Bekheit, A. H.

    2013-08-01

    We model the internal transport barrier "ITB" in edge plasma of small size divertor tokamak with B2SOLPS0.5.2D fluid transport code. The simulation results demonstrated the following: (1) we control the internal transport barrier by altering the edge particle transport through changes the edge toroidal rotation which agree with the result of Burrell et al. (Edge Pedestal control in quiescent H-mode discharges in DIII-D using co-plus counter-neutral beam injection, Nucl Fusion, 49, 085024 (9pp) in 2009). (2) The radial electric field has neoclassical nature near separatrix with discharge by co-injection NBI. (3) The toroidal plasma viscosity has strong influence on the toroidal velocity.

  14. Energy balance of a dielectric barrier discharge reactor for hydrocarbon steam reforming

    International Nuclear Information System (INIS)

    In the future, hydrogen is supposed to play an important role in the worldwide energy supply. It allows a more efficient utilization of fossil fuels and the reduction of noxious emissions, e. g. by fuel cells or the use of hydrogen enriched fuels in combustion engines or gas turbines. Plasma methods are expected to allow low temperature and fuel flexible on-site hydrogen generation. They are also favorable in terms of a dynamic behavior at load changes, which is particularly important in mobile applications. However, one has to ensure an efficient plasma generation. Experiments on methane steam reforming for hydrogen generation with a dielectric barrier discharge (DBD) reactor were performed. A strong temperature rise of the reactor was observed when the plasma was ignited. To investigate the source of this heating effect, the DBD reactor was furnished with a series of temperature sensors and a constant power electrical heating to determine and quantify the input and output heat fluxes of the reactor. It was possible to strike an energy balance over the reactor including both thermal heat fluxes and the reaction enthalpy. It appears that more than 60 % of the electrical energy input is spent for heating of the dielectric barrier. This effect is independent of the gas type or the presence of chemical conversion, since similar results are obtained when pure nitrogen is fed to the DBD reactor. Nevertheless, it has been demonstrated that steam reforming reactions can be induced by DBD at temperatures below 400 Celsius degrees, which is not possible with purely catalytic methods. (author)

  15. Characterization of microwave discharge plasmas for surface processing

    Science.gov (United States)

    Nikolic, Milka

    We have developed several diagnostic techniques to characterize two types of microwave (MW) discharge plasmas: a supersonic flowing argon MW discharge maintained in a cylindrical quartz cavity at frequency ƒ = 2.45 GHz and a pulse repetitive MW discharge in air at ƒ = 9.5 GHz. Low temperature MW discharges have been proven to posses attractive properties for plasma cleaning and etching of niobium surfaces of superconductive radio frequency (SRF) cavities. Plasma based surface modification technologies offer a promising alternative for etching and cleaning of SRF cavities. These technologies are low cost, environmentally friendly and easily controllable, and present a possible alternative to currently used acid based wet technologies, such as buffered chemical polishing (BCP), or electrochemical polishing (EP). In fact, weakly ionized. non-equilibrium, and low temperature gas discharges represent a powerful tool for surface processing due to the strong chemical reactivity of plasma radicals. Therefore, characterizing these discharges by applying non-perturbing, in situ measurement techniques is of vital importance. Optical emission spectroscopy has been employed to analyze the molecular structure and evaluate rotational and vibrational temperatures in these discharges. The internal plasma structure was studied by applying a tomographic numerical method based on the two-dimensional Radon formula. An automated optical measurement system has been developed for reconstruction of local plasma parameters. It was found that excited argon states are concentrated near the tube walls, thus confirming the assumption that the post discharge plasma is dominantly sustained by a travelling surface wave. Employing a laser induced fluorescence technique in combination with the time synchronization device allowed us to obtain time-resolved population densities of some excited atomic levels in argon. We have developed a technique for absolute measurements of electron density based

  16. Investigation on the effect of impurities in xenon based dielectric barrier discharge lamps

    OpenAIRE

    Dagang, A N; Bhosle, S.; Zissis, G.; Corazza, A

    2010-01-01

    Abstract In any discharges, the existence of impurities could give a severe change or bring a negative or positive effect to the discharge and plasma characteristics. The authors purposely added a few kinds of impurities and their effect on the discharge was investigated. The common and typical impurities of H 2, N 2, CO 2 and CH 4 were applied in varying concentration percentages into a xenon DBD lamp. Their discharge condition, emission spectra and electrical characteristics were studied...

  17. 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.

  18. Experimental Determination of Spatial and Temporal Discharge Parameters for an Ambient Pressure Dielectric Barrier Discharge in Helium

    Science.gov (United States)

    Bures, Brian; Bourham, Mohamed

    2004-11-01

    Ambient pressure Dielectric Barrier Discharges (DBD's) are studied for a number of applications. Barrier discharges composed primarily of inert gases are potentially useful for the production of intense excimer light, sterilization of thermally sensitive materials and control of insects for quarantine. The neutral bremsstrahlung technique is used to determine spatial variations of electron density and electron temperature in a parallel plate, helium (99.9% by vol) dielectric barrier discharge operated at an average power density between 50 and 75 mW/cm^3. The applied frequency is varied between 2 kHz and 6 kHz. The time average electron density suggests a more intense discharge near the surface of the electrodes than the bulk of the discharge for all frequencies and power densities. When moving parallel to the electrodes, the electron temperature remains constant, while the electron density is constant within 20% of the average value. A monochromator tuned to a nitrogen ion line (391.4 nm) and a helium line (706.5 nm) has a more intense emission when the electrode is negatively biased.

  19. Microsources of intense fusion in focused discharges of plasma focus

    International Nuclear Information System (INIS)

    High nuclear reactivity within submillimetric domains in the space structure of the pinch of focused discharges has been reported since many years. Now the authors summarize and compare new and previously published data from our experiments which describe the emission of D+ beams and the occurrence of nuclear fusion reactions within submillimetric domains of plasma focus (PF) discharges for W = 5--10 kJ PF machines operating in the neutron optimized mode

  20. 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

  1. Comparison of optical emission spectrums of cold flowing discharge and the post-discharge plasmas of air at low pressure

    OpenAIRE

    İlik, Erkan; AKAN, Tamer; Durmuş, Çağrı; Tanışlı, Murat; Şahin, Neslihan; Mertadam, Sercan

    2015-01-01

    The main differences between cold flowing discharge and the post-discharge plasmas of any gas are intended with the help of new designed plasma generation reactor which Works at low pressure. The up and the middle flanges which made of stainless steel are served as ring electrodes on the plasma generation reactor at low pressure and low temperature. The discharge and the post-discharge plasmas of air are created by means of a d.c. power supply. The reactor both generating post – discharge pla...

  2. Ozone generation in a kHz-pulsed He-O2 capillary dielectric barrier discharge operated in ambient air

    Science.gov (United States)

    Sands, Brian L.; Ganguly, Biswa N.

    2013-12-01

    The generation of reactive oxygen species using nonequilibrium atmospheric pressure plasma jet devices has been a subject of recent interest due to their ability to generate localized concentrations from a compact source. To date, such studies with plasma jet devices have primarily utilized radio-frequency excitation. In this work, we characterize ozone generation in a kHz-pulsed capillary dielectric barrier discharge configuration comprised of an active discharge plasma jet operating in ambient air that is externally grounded. The plasma jet flow gas was composed of helium with an admixture of up to 5% oxygen. A unipolar voltage pulse train with a 20 ns pulse risetime was used to drive the discharge at repetition rates between 2-25 kHz. Using UVLED absorption spectroscopy centered at 255 nm near the Hartley-band absorption peak, ozone was detected over 1 cm from the capillary axis. We observed roughly linear scaling of ozone production with increasing pulse repetition rate up to a "turnover frequency," beyond which ozone production steadily dropped and discharge current and 777 nm O(5P→5S°) emission sharply increased. The turnover in ozone production occurred at higher pulse frequencies with increasing flow rate and decreasing applied voltage with a common energy density of 55 mJ/cm3 supplied to the discharge. The limiting energy density and peak ozone production both increased with increasing O2 admixture. The power dissipated in the discharge was obtained from circuit current and voltage measurements using a modified parallel plate dielectric barrier discharge circuit model and the volume-averaged ozone concentration was derived from a 2D ozone absorption measurement. From these measurements, the volume-averaged efficiency of ozone production was calculated to be 23 g/kWh at conditions for peak ozone production of 41 mg/h at 11 kV applied voltage, 3% O2, 2 l/min flow rate, and 13 kHz pulse repetition rate, with 1.79 W dissipated in the discharge.

  3. Particle densities of the pulsed dielectric barrier discharges in nitrogen at atmospheric pressure

    Science.gov (United States)

    Pan, Jie; Li, Li

    2015-02-01

    Pulsed dielectric barrier discharges (DBDs) have become a promising solution to generate atmospheric-pressure non-equilibrium plasmas. In this work, a one-dimensional fluid model is carried out to research particle densities of the pulsed nitrogen DBDs at atmospheric pressure. Averaged particle densities, time evolutions of axial distributions of particle densities and influences of discharge gap distance dg on the particle densities are systematically illustrated and discussed. The calculation results show that averaged electron densities are lower than averaged N2+ densities, but higher than other averaged ion densities. Time evolutions of axial distributions of electron, N+ and N2+ densities show two peaks during rising and falling phases of applied voltage when dg is 0.2 cm but present gradual increases during pulse width when dg is 0.6 cm, which are similar to those of N2(a‧) and N2(B). Maximums of N3+ densities are close to the momentary cathode under dg of 0.2 cm but locate near the grounded electrode under dg of 0.6 cm, which are alike to those of N2(A) and N2(C). Besides, N4+ densities nearby the momentary anode are higher than those nearby the momentary cathode when dg is 0.2 cm. N(2D) has low averaged particle densities and complex time evolutions compared to N.

  4. Particle densities of the pulsed dielectric barrier discharges in nitrogen at atmospheric pressure

    International Nuclear Information System (INIS)

    Pulsed dielectric barrier discharges (DBDs) have become a promising solution to generate atmospheric-pressure non-equilibrium plasmas. In this work, a one-dimensional fluid model is carried out to research particle densities of the pulsed nitrogen DBDs at atmospheric pressure. Averaged particle densities, time evolutions of axial distributions of particle densities and influences of discharge gap distance dg on the particle densities are systematically illustrated and discussed. The calculation results show that averaged electron densities are lower than averaged N2+ densities, but higher than other averaged ion densities. Time evolutions of axial distributions of electron, N+ and N2+ densities show two peaks during rising and falling phases of applied voltage when dg is 0.2 cm but present gradual increases during pulse width when dg is 0.6 cm, which are similar to those of N2(a′) and N2(B). Maximums of N3+ densities are close to the momentary cathode under dg of 0.2 cm but locate near the grounded electrode under dg of 0.6 cm, which are alike to those of N2(A) and N2(C). Besides, N4+ densities nearby the momentary anode are higher than those nearby the momentary cathode when dg is 0.2 cm. N(2D) has low averaged particle densities and complex time evolutions compared to N. (paper)

  5. The interaction of plasma with quartz surfaces in pinch discharges

    International Nuclear Information System (INIS)

    The interaction of plasma with quartz walls was investigated in theta pinch discharges preionized by axial discharges at filling pressures below 12 mTorr. Implantation and sputtering of hydrogen and deuterium in the surface was deduced from neutron yield and Balmer line intensity measurements. A simple model describing these processes yields an implanted deuterium density of 1.6 x 1016/cm2 and a detrapping cross-section of 5 x 10-17 cm2 for a plasma with about 50 eV particle energy. Impurities within the plasma were observed by line intensity measurements. The vacuum and the composition of the filling gas before and after discharges were analysed by means of a mass spectrometer. Stationary conditions could only be obtained after about 30 discharges. The impurity concentration depends on the energy of the preheating discharge, on filling density, on the fact whether the plasma touches the walls during preheating, and on available sources like back diffusion of pump oil, seals, walls and leaks. (Auth.)

  6. Characteristics of 2-heptanone decomposition using nanosecond pulsed discharge plasma

    Science.gov (United States)

    Nakase, Yuki; Fukuchi, Yuichi; Wang, Douyan; Namihira, Takao; Akiyama, Hidenori; Kumamoto University Collaboration

    2015-09-01

    Volatile organic compounds (VOC) evaporate at room temperature. VOCs typically consist of toluene, benzene and ethyl acetate, which are used in cosmetics, dry cleaning products and paints. Exposure to elevated levels of VOCs may cause headaches, dizziness and irritation to the eyes, nose, and throat; they may also cause environmental problems such as air pollution, acid rain and photochemical smog. As such, they require prompt removal. Nanosecond pulsed discharge is a kind of non-thermal plasma consisting of a streamer discharge. Several advantages of nanosecond pulsed discharge plasma have been demonstrated by studies of our research group, including low heat loss, highly energetic electron generation, and the production of highly active radicals. These advantages have shown ns pulsed discharge plasma capable of higher energy efficiency for processes, such as air purification, wastewater treatment and ozone generation. In this research, nanosecond pulsed discharge plasma was employed to treat 2-heptanone, which is a volatile organic compound type and presents several harmful effects. Characteristics of treatment dependent on applied voltage, gas flow rate and input energy density were investigated. Furthermore, byproducts generated by treatment were also investigated.

  7. Bulk plasma properties in the pulsed glow discharge

    International Nuclear Information System (INIS)

    This work focuses on the spatial and temporal characteristics of a glow discharge plasma operated with power pulses of 5 ms in duration at 25% duty cycle. Interpretation of emission data provides insight into the nature of the plasma at each instant of a typical pulse cycle and at each position in space. Because the bulk plasma properties affect the distribution of excited energy levels of the sputtered atoms, an improved understanding of the plasma affords the ability to select conditions that enhance analytically important emission lines. Optical emission spectroscopy was used to determine the relative populations of excited states for atoms and ions during the initial breakdown, the steady state and the recombining periods of the discharge pulse cycle. The plasma is highly ionizing in nature at the time of breakdown--with lower excited states being overpopulated--before reaching the steady state, or plateau, period, also ionizing in nature. These behaviors arise from a loss of charged particles and photons to the surroundings that shifts the plasma away from Saha and Boltzmann balances during these periods. The post-pulse period typically displays recombining behavior, characterized by population inversion for selected species--except for regions close to the cathode, where electrons and ions are lost by diffusion and are not available for recombination. The sputtered analyte atom emissions closely mimic those of the plasma bath gas, except that their emissions persevere for longer in the recombining after-peak period than do the discharge gas species

  8. Dynamics of plasma evolution in a nanosecond underwater discharge

    International Nuclear Information System (INIS)

    A positive discharge in water is generated by applying a 30 ns high-voltage (HV) pulse on a micrometre scale electrode. The applied voltage ranges from 6 to 15 kV and a fast plasma propagating mode is launched with a velocity of up to 60 km s−1. Time-resolved shadowgraphy and spectroscopy are performed to monitor the time evolution of the discharge structure and of the plasma emission spectra. By analysing the dynamics of the shock front velocity and the lateral expansion of the plasma channel, it is possible to estimate the pressure at the ignition of the plasma by two independent methods: very good agreement is found at 6 kV giving initial pressures of 0.4 GPa and 0.3 GPa, respectively. At 15 kV, only the shock front velocity method is applicable under our experimental conditions, giving an estimate of the initial pressure of 5.8 GPa. Such high initial pressures show that, under a nanosecond HV pulse, the plasma is ignited directly in the dense phase. Emission spectra show a strong continuum emission as well as a broad Balmer α line with a strong red shift, with an estimate of the initial plasma density of 1.3 × 1026 m−3. The relaxation of discharge pressure and plasma density is studied under a series of six successive pulses. (paper)

  9. An investigation of dielectric barrier discharge in Ar and Ar/NH{sub 3} mixture using cross-correlation spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kloc, P; Trunec, D; Navratil, Z [Department of Physical Electronics, Faculty of Science, Masaryk University, Kotlarska 2, 611 37 Brno (Czech Republic); Wagner, H-E [Institute of Physics, University of Greifswald, F.-Hausdorff-Str 6., 17489 Greifswald (Germany); Fedoseev, G, E-mail: kloc@physics.muni.c [Department of Material Science, Moscow State University of Design and Technology, Sadovnicheskaya str. 33, 117997 Moscow (Russian Federation)

    2010-09-01

    Dielectric barrier discharges (BDs) are known to operate in two distinctive modes. The filamentary mode of BD is characterized by a large number of short lasting spatially bounded microdischarges. This type of discharge is typical for most cases of BDs at atmospheric pressure. Under some specific conditions another form of BD may arise. In this mode plasma uniformly covers the whole electrode area. This mode is usually referred to as the diffuse or homogeneous mode of BD. This work presents studies of the filamentary mode of BD in argon and its transition to the diffuse mode by ammonia addition. The discharges were investigated by means of cross-correlation spectroscopy. Particularly, the influence of electrode shape, discharge gap and the influence of ammonia admixture on discharge development were studied. The measurement offers results with high temporal and spatial resolution which are useful for comparison with results of numerical models. The obtained results include the electrical current measurement of discharge in several ammonia admixtures to argon. The diffuse discharge appeared at ammonia admixture above 3 vol%. The observed propagation of streamer in discharge in pure argon for two different electrode configurations is presented. When compared with discharge in pure argon the streamer velocity is decreased for 0.1 vol% ammonia admixture. With increasing ammonia concentration the streamer velocity increases again. The behaviour of presented impurities was observed and the results are included in this report. The basic model of the discharge kinetic is included. For reduced electric field below 10 Td the electron drift is much higher in argon-ammonia mixture than in pure argon.

  10. EUV sources using Xe and Sn discharge plasmas

    International Nuclear Information System (INIS)

    This paper reports the basic results that have been obtained at the SRC RF TRINITI (the former Branch of the Kurchatov Institute of Atomic Energy). The work deals with the development of high power discharge produced plasma EUV sources that can meet the requirements of high volume manufacturing lithography tools. Solving the problem of extremely high thermal loads on the electrodes of a EUV source by moving away the electrode surfaces from the plasma and using both multi-discharge systems and rotating Sn-covered disc electrodes is discussed

  11. Simulation of DBD plasma actuators, and nanoparticle-plasma interactions in argon-hydrogen CCP RF discharges

    Science.gov (United States)

    Mamunuru, Meenakshi

    The focus of this work is modeling and simulation of low temperature plasma discharges (LTPs). The first part of the thesis consists of the study of dielectric barrier (DBD) plasma actuators. Use of DBD plasma actuators on airfoil surfaces is a promising method for increasing airfoil efficiency. Actuators produce a surface discharge that causes time averaged thrust in the neutral gas. The thrust modifies the boundary layer properties of the flow and prevents the occurrence of separation bubbles. In simulating the working of an actuator, the focus is on the spatial characteristics of the thrust produced by the discharge over very short time and space scales. The results provide an understanding of the causes of thrust, and the basic principles behind the actuator operation. The second part of this work focusses on low pressure plasma discharges used for silicon nanoparticle synthesis. When reactive semiconductor precursor gases are passed through capacitively coupled plasma (CCP) radio frequency (RF) reactors, nano sized particles are formed. When the reactors are operated at high enough powers, a very high fraction of the nanoparticles are crystallized in the chamber. Nanoparticle crystallization in plasma is a very complex process and not yet fully understood. It can be inferred from experiments that bulk and surface processes initiated due to energetic ion impaction of the nanoparticles are responsible for reordering of silicon atoms, causing crystallization. Therefore, study of plasma-particle interactions is the first step towards understanding how particles are crystallized. The specific focus of this work is to investigate the experimental evidence that hydrogen gas presence in argon discharges used for silicon nanocrystal synthesis, leads to a superior quality of nanocrystals. Influence of hydrogen gas on plasma composition and discharge characteristics is studied. Via Monte Carlo simulation, distribution of ion energy impacting particles surface is studied

  12. Optical emission spectroscopy observations of fast pulsed capillary discharge plasmas

    Science.gov (United States)

    Avaria, G.; Ruiz, M.; Guzmán, F.; Favre, M.; Wyndham, E. S.; Chuaqui, H.; Bhuyan, H.

    2014-05-01

    We present time resolved optical emission spectroscopic (OES) observations of a low energy, pulsed capillary discharage (PCD). The optical emission from the capillary plasma and plasma jets emitted from the capillary volume was recorded with with a SpectraPro 275 spectrograph, fitted with a MCP gated OMA system, with 15 ns time resolution. The discharge was operated with different gases, including argon, nitrogen, hydrogen and methane, in a repetitive pulsed discharge mode at 10-50 Hz, with, 10-12 kV pulses applied at the cathode side. The time evolution of the electron density was measured using Stark broadening of the Hβ line. Several features of the capillary plasma dynamics, such as ionization growth, wall effects and plasma jet evolution, are inferred from the time evolution of the optical emission.

  13. Plasma Dynamics of Capillary Discharges for the BELLA project

    Science.gov (United States)

    Stoltz, Peter; Hakim, Ammar; Loverich, John; Fillmore, David; Johnson, Jeffrey; Geddes, Cameron; Esarey, Eric; Mittelberger, Daniel; Bulanov, Stepan; Gonsalves, Anthony; Leemans, Wim

    2010-11-01

    Capillary discharges to form a meter-scale plasma waveguide are important for 10 GeV scale laser plasma accelerator experiments on the BELLA laser in progress at Lawrence Berkeley National Laboratory. We present simulation results of capillary plasma properties, including radial density and temperature profiles, using the Nautilus code. An effect known to play a dominant role is the transfer of heat from the plasma to the capillary wall. We present benchmark results for heat transfer modeling with Nautilus in the regime of interest to capillary discharges. We also discuss the relative importance of diffusion, Ohm's law, and applied solenoidal fields on the radial profiles needed for experiments. For instance, some previous models estimate applied solenoidal fields could increase on-axis temperatures by roughly a factor of two, and we compare with these estimates. Finally, we compare radial profile results with other simulation results and with recent measurements made at LBNL.

  14. High density magnetized plasma produced in a laboratory discharge

    OpenAIRE

    Krafft, C.; Matthieussent, G.; Thévenet, P.; Godiot, J.

    1991-01-01

    The main features of a laboratory experiment devoted to the study of beam-plasma interactions are described ; the production and the principal characteristics of a magnetized plasma created by a steady state or pulsed discharge are presented ; a description of the electron gun is given so as the first results concerning the injection of the monokinetic electron beam in the neutral Argon gas.

  15. Mode transition of a Hall thruster discharge plasma

    International Nuclear Information System (INIS)

    A Hall thruster is a cross-field plasma device used for spacecraft propulsion. An important unresolved issue in the development of Hall thrusters concerns the effect of discharge oscillations in the range of 10–30 kHz on their performance. The use of a high speed Langmuir probe system and ultra-fast imaging of the discharge plasma of a Hall thruster suggests that the discharge oscillation mode, often called the breathing mode, is strongly correlated to an axial global ionization mode. Stabilization of the global oscillation mode is achieved as the magnetic field is increased and azimuthally rotating spokes are observed. A hybrid-direct kinetic simulation that takes into account the transport of electronically excited atoms is used to model the discharge plasma of a Hall thruster. The predicted mode transition agrees with experiments in terms of the mean discharge current, the amplitude of discharge current oscillation, and the breathing mode frequency. It is observed that the stabilization of the global oscillation mode is associated with reduced electron transport that suppresses the ionization process inside the channel. As the Joule heating balances the other loss terms including the effects of wall loss and inelastic collisions, the ionization oscillation is damped, and the discharge oscillation stabilizes. A wide range of the stable operation is supported by the formation of a space charge saturated sheath that stabilizes the electron axial drift and balances the Joule heating as the magnetic field increases. Finally, it is indicated from the numerical results that there is a strong correlation between the emitted light intensity and the discharge current.

  16. CO and byproduct formation during CO₂ reduction in dielectric barrier discharges

    Energy Technology Data Exchange (ETDEWEB)

    Brehmer, F. [Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); AFS GmbH, Von-Holzapfel-Straße 10, 86497 Horgau (Germany); Welzel, S.; Sanden, M. C. M. van de [Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Dutch Institute for Fundamental Energy Research, P.O. Box 1207, 3430 BE Nieuwegein (Netherlands); Engeln, R. [Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands)

    2014-09-28

    The dissociation of CO₂ and the formation of CO, O₃, and O² were studied in a dielectric barrier discharge (DBD) at atmospheric pressure by means of ex-situ infrared absorption spectroscopy. CO mixing ratios of 0.1%–4.4% were determined for specific injected energies between 0.1 and 20 eV per molecule (0.3–70 kJ/l). A lower limit of the gas temperature of 320–480 K was estimated from the wall temperature of the quartz reactor as measured with an infrared camera. The formation of CO in the DBD could be described as function of the total number of transferred charges during the residence time of the gas in the active plasma zone. An almost stoichiometric CO:O₂ ratio of 2:1 was observed along with a strongly temperature dependent O₃ production up to 0.075%. Although the ideal range for an efficient CO₂ dissociation in plasmas of 1 eV per molecule for the specific injected energy was covered, the energy efficiency remained below 5% for all conditions. The present results indicate a reaction mechanism which is initiated by electron impact processes followed by charge transfer reactions and non-negligible surface enhanced O and CO recombination. While electron-driven CO₂ dissociation is relatively energy inefficient by itself, fast O recombination and the low gas temperatures inhibit the synergistic reuse of atomic oxygen in a secondary CO₂ + O dissociation step.

  17. Degradation of m-cresol in aqueous solution by dielectric barrier discharge

    International Nuclear Information System (INIS)

    It was carried out a theoretical and experimental study of the m-cresol degradation in aqueous solution using a non-thermal plasma induced by dielectric barrier discharge. For the experimental setup a coaxial reactor vertically placed was used. Wherein a liquid solution flowing inside the internal electrode was impelled by a peristaltic pump and falling over the external surface of the internal electrode. Working gas was applied in a parallel direction respect to the surface of the liquid and inside of the quartz tube. Non-thermal plasma was generated at the gas-liquid interface in Ar-O2 gas mixtures with a high-voltage power supply system. The electric power applied ranged from 10–60W at a 3.0 kHz frequency. The initial concentration of m-cresol was of 5 × 10−3 mol/L, and the removal efficiency up to 97.3% was obtained after 1 h of treatment. For the theoretical study a simplified model of the chemical kinetics was developed where the temporary evolution of the compounds generated in the process of degradation of the m-cresol was analyzed. Byproducts as oxalic acid and CO2 were found.

  18. Two-dimensional simulation of discharge channels in atmospheric-pressure single dielectric barrier discharges

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jiao; Wang, Yanhui, E-mail: wangyh@dlut.edu.cn; Wang, Dezhen, E-mail: wangdez@dlut.edu.cn [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)

    2015-11-15

    A two-dimensional fluid model is developed to study the filaments (or discharge channels) in atmospheric-pressure discharge with one plate electrode covered by a dielectric layer. Under certain discharge parameters, one or more stable filaments with wide radii could be regularly arranged in the discharge space. Different from the short-lived randomly distributed microdischarges, this stable and thick filament can carry more current and have longer lifetime. Because only one electrode is covered by a dielectric layer in the simulation, the formed discharge channel extends outwards near the dielectric layer and shrinks inwards near the naked electrode, agreeing with the experimental results. In this paper, the evolution of channel is studied, and its behavior is like a streamer or an ionization wave, but the propagation distance is short. The discharge parameters such as voltage amplitude, electrode width, and N{sub 2} impurities content could significantly influence the number of discharge channel, which is discussed in the paper.

  19. 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.

  20. On the stability of a homogeneous barrier discharge in nitrogen relative to radial perturbations

    International Nuclear Information System (INIS)

    The influence of small radial perturbations of the cathode current on the characteristics of a homogeneous barrier discharge in nitrogen is investigated on the basis of a two-dimensional fluid model. In a Townsend discharge, radial fluctuations are substantially suppressed, which is the evidence of its stability. The oscillative mode of the Townsend discharge is also stable with regard to radial perturbations. As the discharge turns into a form controlled by spatial charge (a streamer is developed), disturbances of all radii grow in time. Such a behaviour testifies the instability of a streamer front and may cause the discharge filamentation. Since only the Townsend discharge is stable, it is possible to use a one-dimensional model to determine the domain of existence for a homogeneous discharge. The study of homogeneity domains by means of the one-dimensional model shows that at relatively large values of the voltage growth rate, discharge gap width, or capacitance of dielectric barriers the discharge tends to be filamentary. Calculation of the domain of the discharge homogeneity agrees satisfactory with the experimental data available as the account is taken for the gas heating