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Sample records for barrier discharge dbd

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

    NASA Astrophysics Data System (ADS)

    Pal, U. N.; Kumar, M.; Khatun, H.; Sharma, A. K.

    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 N2/Ar/Xe gas at different pressures. A proper ultra high vacuum system and gas filing system has been made for the processing & 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 & 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.

  2. Computational Modeling of the Dielectric Barrier Discharge (DBD) Device for Aeronautical Applications

    DTIC Science & Technology

    2006-06-01

    Dielectric Barrier Discharge The Dielectric Barrier Discharge (DBD) device has been put to use since 1857 when Werner von Siemens used to produce...x y s t s t x y x ys t s t s t s t x y x y x yn S L t nx + − − Γ − Γ = − − Δ + Δ (18) and 1 1 2 2 , , , , ,, , , , , 1 , 1...driven flux and the thermal flux were oppositely directed. ( ), , , , 1s t s t s t s tadjacent Scharfetter Gummel thermal adjacenttn S L nx − − Δ = Γ

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

    NASA Astrophysics Data System (ADS)

    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.

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

    SciTech Connect

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

    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. Uniformity analysis of dielectric barrier discharge (DBD) processed polyethylene terephthalate (PET) surface

    NASA Astrophysics Data System (ADS)

    Liu, Chaozong; Brown, Norman M. D.; Meenan, Brian J.

    2006-01-01

    A dielectric barrier discharge (DBD) plasma, operating in air at atmospheric pressure, has been used to induce changes in the surface properties of polyethylene terephthalate (PET) films. The effects that the key DBD operating parameters: discharge power, processing speed, processing duration, and electrode configurations, have on producing wettability changes in the PET surface region have been investigated. The approach taken involves the application of an Taguchi experimental design and robust analysis methodology. The various data sets obtained from these analyses have been used to studies the effect of the operating parameters on the surface uniformity and efficiency of the said treatment. In general, the results obtained indicate that DBD plasma processing is an effective method for the controlled surface modification of PET. Relatively short exposures to the atmospheric pressure discharge produces significant wettability changes at the polymer film surface, as indicted by pronounced reductions in the water contact angle measured. It was observed that the wettability of the resultant surface shows no significant differences in respect to orientation parallel (L-direction) or perpendicular (T-direction) to the electrode long axis. However, there was significant differences between the data obtained from these two orientations. Analysis of the role of each of the operating parameters concerned shows that they have a selective effectiveness with respect to resultant surface modification in terms of uniformity of modification and wettability. The number of treatment cycles and the electrode configuration used were found to have the most significant effects on the homogeneity of the resultant PET surface changes in L- and T-orientation, respectively. On the other hand, the applied power showed no significant role in this regard. The number of treatment cycles was found to be the dominant factor (at significance level of 0.05) in respect of water contact angle

  6. Alumina and quartz as dielectrics in a dielectric barrier discharges DBD system for CO2 hydrogenation

    NASA Astrophysics Data System (ADS)

    Mora, E. Y.; Sarmiento, A.; Vera, E.

    2016-02-01

    In this work was studied the CO2 carbon dioxide treatment, which is a pollutant gas and the main cause of global warming. For this aim, plasma was generated, through dielectric barrier discharges DBD, using hydrogen H2 together with the CO2 as reaction gases. There were used as dielectrics, alumina and quartz tubes of identical geometry. It was studied the CO2 conversion in function of mixture composition CO2+H2, of the electrical power and the operation frequency, for three different gas flows. In all cases it was achieved better conversion levels with the alumina; this is because the alumina has a relative dielectric permittivity coefficient higher than the quartz. As products of CO2 conversion in the chemical reactions, water H2O and methane gas CH4 were identified. The CO2 conversion percentage to fixed work conditions was higher with the decrease the quantity of this gas in the mixture, with increase the active electrical power, and with decrease the operation electrical frequency.

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

    NASA Technical Reports Server (NTRS)

    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.

  8. Nonthermal Dielectric Barrier Discharge (DBD) Plasma Suppresses Herpes Simplex Virus Type 1 (HSV-1) Replication in Corneal Epithelium

    PubMed Central

    Alekseev, Oleg; Donovan, Kelly; Limonnik, Vladimir; Azizkhan-Clifford, Jane

    2014-01-01

    Purpose Herpes keratitis (HK) is the leading cause of cornea-derived and infection-associated blindness in the developed world. Despite the availability of effective antivirals, some patients develop refractory disease, drug-resistant infection, and topical toxicity. A nonpharmaceutical treatment modality may offer a unique advantage in the management of such cases. This study investigated the antiviral effect of nonthermal dielectric barrier discharge (DBD) plasma, a partially ionized gas that can be applied to organic substances to produce various biological effects. Methods Human corneal epithelial cells and explanted corneas were infected with herpes simplex virus type 1 (HSV-1) and exposed to culture medium treated with nonthermal DBD plasma. The extent of infection was measured by plaque assay, quantitative PCR, and Western blot. Corneal toxicity assessment was performed with fluorescein staining, histologic examination, and 8-OHdG detection. Results Application of DBD plasma–treated medium to human corneal epithelial cells and explanted corneas produced a dose-dependent reduction of the cytopathic effect, viral genome replication, and the overall production of infectious viral progeny. Toxicity studies showed lack of detrimental effects in explanted human corneas. Conclusions Nonthermal DBD plasma substantially suppresses corneal HSV-1 infection in vitro and ex vivo without causing pronounced toxicity. Translational Relevance Nonthermal plasma is a versatile tool that holds great biomedical potential for ophthalmology, where it is being investigated for wound healing and sterilization and is already in use for ocular microsurgery. The anti-HSV-1 activity of DBD plasma demonstrated here could be directly translated to the clinic for use against drug-resistant herpes keratitis. PMID:24757592

  9. Towards In-Flight Applications? - Requirements on the Dielectric Barrier Discharge (DBD) Plasma Actuator (PA)

    NASA Astrophysics Data System (ADS)

    Kriegseis, Jochen; Simon, Bernhard; Grundmann, Sven

    2016-11-01

    Most of today's flow control (FC) efforts with DBD show a rather one-sided picture. Typically, either the discharge properties are discussed extensively or FC achievements are reported. The former group of contributions only pays limited attention to implications and consequences of most characteristics with respect to subsequent control steps for successful DBD-based FC - the latter group mostly ignores changing discharge properties, thus varying control authority for the respective applications when changes of environment, PA health state or simply a varied angle-of-attack are to be considered. In addition, there still remains a fair bit of uncertainty regarding a universal PA-evaluation metric, such that some of the most promising quantities/characteristics for successful controller operation remain largely untouched from the community. The purpose of the present work is to outline the requirement profile of PAs in one coherent story starting from electrical issues all the way down the road to in-flight FC success, where particular emphasis is placed on the interplay of the involved subtopics. It is hypothesized that such a clear guideline is the only way to advance beyond the present level of lab studies, where there still is an obvious lack of real flight applications.

  10. Dielectric Barrier Discharge (DBD) Plasma Assisted Synthesis of Ag₂O Nanomaterials and Ag₂O/RuO₂ Nanocomposites.

    PubMed

    Ananth, Antony; Mok, Young Sun

    2016-02-26

    Silver oxide, ruthenium oxide nanomaterials and its composites are widely used in a variety of applications. Plasma-mediated synthesis is one of the emerging technologies to prepare nanomaterials with desired physicochemical properties. In this study, dielectric barrier discharge (DBD) plasma was used to synthesize Ag₂O and Ag₂O/RuO₂ nanocomposite materials. The prepared materials showed good crystallinity. The surface morphology of the Ag₂O exhibited "garland-like" features, and it changed to "flower-like" and "leaf-like" at different NaOH concentrations. The Ag₂O/RuO₂ composite showed mixed structures of aggregated Ag₂O and sheet-like RuO₂. Mechanisms governing the material's growth under atmospheric pressure plasma were proposed. Chemical analysis was performed using Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Thermogravimetric analysis (TGA) showed the thermal decomposition behavior and the oxygen release pattern.

  11. Non-Thermal Dielectric Barrier Discharge (DBD) Effects on Proliferation and Differentiation of Human Fibroblasts Are Primary Mediated by Hydrogen Peroxide

    PubMed Central

    Demir, Erhan; Hoffmanns, Martin A.; Baldus, Sabrina; Fuchs, Paul C.; Awakowicz, Peter; Suschek, Christoph V.; Opländer, Christian

    2015-01-01

    The proliferation of fibroblasts and myofibroblast differentiation are crucial in wound healing and wound closure. Impaired wound healing is often correlated with chronic bacterial contamination of the wound area. A new promising approach to overcome wound contamination, particularly infection with antibiotic-resistant pathogens, is the topical treatment with non-thermal “cold” atmospheric plasma (CAP). Dielectric barrier discharge (DBD) devices generate CAP containing active and reactive species, which have antibacterial effects but also may affect treated tissue/cells. Moreover, DBD treatment acidifies wound fluids and leads to an accumulation of hydrogen peroxide (H2O2) and nitric oxide products, such as nitrite and nitrate, in the wound. Thus, in this paper, we addressed the question of whether DBD-induced chemical changes may interfere with wound healing-relevant cell parameters such as viability, proliferation and myofibroblast differentiation of primary human fibroblasts. DBD treatment of 250 μl buffered saline (PBS) led to a treatment time-dependent acidification (pH 6.7; 300 s) and coincidently accumulation of nitrite (~300 μM), nitrate (~1 mM) and H2O2 (~200 μM). Fibroblast viability was reduced by single DBD treatments (60–300 s; ~77–66%) or exposure to freshly DBD-treated PBS (60–300 s; ~75–55%), accompanied by prolonged proliferation inhibition of the remaining cells. In addition, the total number of myofibroblasts was reduced, whereas in contrast, the myofibroblast frequency was significantly increased 12 days after DBD treatment or exposure to DBD-treated PBS. Control experiments mimicking DBD treatment indicate that plasma-generated H2O2 was mainly responsible for the decreased proliferation and differentiation, but not for DBD-induced toxicity. In conclusion, apart from antibacterial effects, DBD/CAP may mediate biological processes, for example, wound healing by accumulation of H2O2. Therefore, a clinical DBD treatment must be well

  12. Non-Thermal Dielectric Barrier Discharge (DBD) Effects on Proliferation and Differentiation of Human Fibroblasts Are Primary Mediated by Hydrogen Peroxide.

    PubMed

    Balzer, Julian; Heuer, Kiara; Demir, Erhan; Hoffmanns, Martin A; Baldus, Sabrina; Fuchs, Paul C; Awakowicz, Peter; Suschek, Christoph V; Opländer, Christian

    2015-01-01

    The proliferation of fibroblasts and myofibroblast differentiation are crucial in wound healing and wound closure. Impaired wound healing is often correlated with chronic bacterial contamination of the wound area. A new promising approach to overcome wound contamination, particularly infection with antibiotic-resistant pathogens, is the topical treatment with non-thermal "cold" atmospheric plasma (CAP). Dielectric barrier discharge (DBD) devices generate CAP containing active and reactive species, which have antibacterial effects but also may affect treated tissue/cells. Moreover, DBD treatment acidifies wound fluids and leads to an accumulation of hydrogen peroxide (H2O2) and nitric oxide products, such as nitrite and nitrate, in the wound. Thus, in this paper, we addressed the question of whether DBD-induced chemical changes may interfere with wound healing-relevant cell parameters such as viability, proliferation and myofibroblast differentiation of primary human fibroblasts. DBD treatment of 250 μl buffered saline (PBS) led to a treatment time-dependent acidification (pH 6.7; 300 s) and coincidently accumulation of nitrite (~300 μM), nitrate (~1 mM) and H2O2 (~200 μM). Fibroblast viability was reduced by single DBD treatments (60-300 s; ~77-66%) or exposure to freshly DBD-treated PBS (60-300 s; ~75-55%), accompanied by prolonged proliferation inhibition of the remaining cells. In addition, the total number of myofibroblasts was reduced, whereas in contrast, the myofibroblast frequency was significantly increased 12 days after DBD treatment or exposure to DBD-treated PBS. Control experiments mimicking DBD treatment indicate that plasma-generated H2O2 was mainly responsible for the decreased proliferation and differentiation, but not for DBD-induced toxicity. In conclusion, apart from antibacterial effects, DBD/CAP may mediate biological processes, for example, wound healing by accumulation of H2O2. Therefore, a clinical DBD treatment must be well-balanced in

  13. Fast enhancement on hydrophobicity of poplar wood surface using low-pressure dielectric barrier discharges (DBD) plasma

    NASA Astrophysics Data System (ADS)

    Chen, Weimin; Zhou, Xiaoyan; Zhang, Xiaotao; Bian, Jie; Shi, Shukai; Nguyen, Thiphuong; Chen, Minzhi; Wan, Jinglin

    2017-06-01

    The hydrophilicity of woody products leads to deformation and cracks, which greatly limits its applications. Low-pressure dielectric barrier discharge (DBD) plasma using hexamethyldisiloxane was applied in poplar wood surface to enhance the hydrophobicity. The chemical properties, micro-morphology, and contact angles of poplar wood surface before and after plasma treatment were investigated by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), x-ray photoelectron spectroscopy (XPS), scanning electron microscope and energy dispersive analysis of X-ray (SEM-EDX), atomic force microscopy (AFM), and optical contact angle measurement (OCA). Moreover, tinfoil film was used as the base to reveal the enhancement mechanism. The results showed that hexamethyldisiloxane monomer is first broken into several fragments with active sites and hydrophobic chemical groups. Meanwhile, plasma treatment results in the formation of free radicals and active sites in the poplar wood surface. Then, the fragments are reacted with free radicals and incorporated into the active sites to form a network structure based on the linkages of Si-O-Si and Sisbnd Osbnd C. Plasma treatment also leads to the formation of acicular nano-structure in poplar wood surface. These facts synergistically enhance the hydrophobicity of poplar wood surface, demonstrating the dramatically increase in the equilibrium contact angle by 330%.

  14. An in situ and downstream study of non-thermal plasma chemistry in an air fed dielectric barrier discharge (DBD)

    NASA Astrophysics Data System (ADS)

    Al-Abduly, Abdullah; Christensen, Paul

    2015-12-01

    This paper reports a spectroscopic study of non-thermal plasma chemistry in an air-fed dielectric barrier discharge (DBD) plasma jet. In situ analysis (i.e. the analysis of the plasma glow) and downstream analysis were carried out to identify and monitor species produced in the plasma as they propagate from the plasma glow to downstream regions. The analyses were carried out using Fourier Transform InfraRed (FTIR) and UV-Vis spectroscopies. The species: O3, N2O5, N2O, HNO3, CO2, CO and, for the first time, a vibrationally excited form of CO2 (i.e. \\text{CO}2* (v)) were identified in the plasma glow, while O3, N2O5, HNO3 and N2O were detected in the downstream exhaust. The behaviour of these species was monitored as a function of a range of experimental conditions including: input power, gas flow rate, relative humidity, gas temperature and feed gas composition. In addition, the uncertainty associated with UV-vis detection of ozone in the presence of N2O5 and/or HNO3 as interfering species was determined.

  15. The topical use of non-thermal dielectric barrier discharge (DBD): nitric oxide related effects on human skin.

    PubMed

    Heuer, Kiara; Hoffmanns, Martin A; Demir, Erhan; Baldus, Sabrina; Volkmar, Christine M; Röhle, Mirco; Fuchs, Paul C; Awakowicz, Peter; Suschek, Christoph V; Opländer, Christian

    2015-01-30

    Dielectric barrier discharge (DBD) devices generate air plasma above the skin containing active and reactive species including nitric oxide (NO). Since NO plays an essential role in skin physiology, a topical application of NO by plasma may be useful in the treatment of skin infections, impaired microcirculation and wound healing. Thus, after safety assessments of plasma treatment using human skin specimen and substitutes, NO-penetration through the epidermis, the loading of skin tissue with NO-derivates in vitro and the effects on human skin in vivo were determined. After the plasma treatment (0-60 min) of skin specimen or reconstructed epidermis no damaging effects were found (TUNEL/MTT). By Franz diffusion cell experiments plasma-induced NO penetration through epidermis and dermal enrichment with NO related species (nitrite 6-fold, nitrate 7-fold, nitrosothiols 30-fold) were observed. Furthermore, skin surface was acidified (~pH 2.7) by plasma treatment (90 s). Plasma application on the forearms of volunteers increased microcirculation fourfold in 1-2 mm and twofold in 6-8 mm depth in the treated skin areas. Regarding the NO-loading effects, skin acidification and increase in dermal microcirculation, plasma devices represent promising tools against chronic/infected wounds. However, efficacy of plasma treatment needs to be quantified in further studies and clinical trials.

  16. Statistical analysis of the effect of dielectric barrier discharge (DBD) operating parameters on the surface processing of poly(methylmethacrylate) film

    NASA Astrophysics Data System (ADS)

    Liu, Chaozong; Brown, Norman M. D.; Meenan, Brian J.

    2005-02-01

    A dielectric barrier discharge (DBD) plasma, operating in air at atmospheric pressure, has been used to induce changes in the surface properties of poly(methylmethacrylate) (PMMA) films. The relative effects that key DBD operating parameters, specifically: discharge power, electrode gap and duration of exposure have on producing chemical and microstructural changes in the polymer surface region have been investigated. The approach taken involves the application of an orthogonal array experimental design and statistical analysis methodology. The various data sets obtained from these analyses have been used to develop an equation in which induced changes in the surface properties of the DBD modified PMMA films are expressed in terms of the effectiveness of the various processing parameters in producing them. In general, the results obtained clearly indicate that DBD plasma processing is an effective method for the controlled surface modification of PMMA. Relatively short exposures to the atmospheric pressure discharge produces a significant amount of oxygen incorporation at the surface as indicted by a pronounced reduction in water contact angle. Analysis of the role of each of the operating parameters concerned shows that they do indeed have selective effectiveness for inducing resultant surface modification. Duration of exposure to the DBD plasma, expressed here as the number of treatment cycles at a given speed of specimen transit through the electrode gap, was found to play a major role in decreasing the surface wettability of PMMA. Conversely, the magnitude of the discharge power was not a significant parameter in this regard. In contrast, the value of the applied power played the dominant role in achieving the observed enrichment of the surface oxygen abundance, as measured by XPS, with the duration of exposure to the discharge playing a secondary role in this case. The nature and scale of the induced surface changes that originate from the various processing

  17. Dielectric Barrier Discharge (DBD) Plasma Assisted Synthesis of Ag2O Nanomaterials and Ag2O/RuO2 Nanocomposites

    PubMed Central

    Ananth, Antony; Mok, Young Sun

    2016-01-01

    Silver oxide, ruthenium oxide nanomaterials and its composites are widely used in a variety of applications. Plasma-mediated synthesis is one of the emerging technologies to prepare nanomaterials with desired physicochemical properties. In this study, dielectric barrier discharge (DBD) plasma was used to synthesize Ag2O and Ag2O/RuO2 nanocomposite materials. The prepared materials showed good crystallinity. The surface morphology of the Ag2O exhibited “garland-like” features, and it changed to “flower-like” and “leaf-like” at different NaOH concentrations. The Ag2O/RuO2 composite showed mixed structures of aggregated Ag2O and sheet-like RuO2. Mechanisms governing the material’s growth under atmospheric pressure plasma were proposed. Chemical analysis was performed using Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Thermogravimetric analysis (TGA) showed the thermal decomposition behavior and the oxygen release pattern. PMID:28344299

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

    NASA Technical Reports Server (NTRS)

    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

  19. Investigation of Ozone Yield of Air Fed Ozonizer by High Pressure Homogeneous Dielectric Barrier Discharge

    DTIC Science & Technology

    2013-07-01

    homogeneous dielectric barrier discharge ( DBD ) in dry air by using a simple DBD device. So far, we have tried to apply the homogeneous DBD to an...specific input energy region. In this work, we investigated the effect of gas pressure (from 0.1 MPa to 0.2 MPa) on the ozone yield by homogeneous DBD . The...homogeneous DBD decreased with increasing the gas pressure. 1. Introduction The dielectric barrier discharge ( DBD ) is composed of many filamentary micro

  20. Catalytic oxidation of benzene using DBD corona discharges.

    PubMed

    Lu, B; Zhang, X; Yu, X; Feng, T; Yao, S

    2006-09-01

    Plasma oxidation of benzene (C(6)H(6)) in oxygen and nitrogen was investigated using a dielectric barrier discharge (DBD) reactor with or without MnO2 or TiO2 at atmospheric pressure and without external heating except plasma heating. An alternative current power supply was used to generate corona discharges for the plasma oxidation. The energy density was controlled under 200 J/L to keep an increase in gas temperature less than 167 K. C(6)H(6) was oxidized to carbon monoxide (CO) and dioxide (CO(2)). Typically, the energy efficiency at an energy density of 92J/L was about 0.052, 0.039, and 0.024 mol/kWh with MnO2, TiO2, and without MnO2 and TiO2, respectively. Benzene oxidation mechanism was mentioned. A comparison on energy efficiency as a function of initial concentration of hydrocarbons, inorganic sulphur compounds, and chloro (fluoro and bromo) carbons was given.

  1. About the development of single microdischarges in dielectric barrier discharges in CO2 and CO2/N2 gas mixtures. DBD-MDs in CO2 and CO2/N2

    NASA Astrophysics Data System (ADS)

    Brandenburg, Ronny; Sarani, Abdollah

    2017-08-01

    The conversion of carbon dioxide as one of the main greenhouse gases into carbon monoxide as a chemical feedstock is considered as so-called carbon capture usage technology. Recently it was shown, that the dissociation of carbon dioxide to carbon monoxide in Dielectric Barrier Discharges can be enhanced by the addition of nitrogen gas. Here, the development of microdischarges in CO2 and CO2/N2 gas mixtures is studied. Therefore, a single filament DBD arrangement operated under sinusoidal high-voltage is investigated by means of spectroscopic and electrical diagnostics with high spatial and temporal resolution and sensitivity. The filament development is similar as in air or other nitrogen-oxygen gas mixtures, but the gas composition influences the duration and other parameters. The higher the CO2 content the weaker the filaments and the faster the quenching of excited molecular states. The optimum power dissipation into single discharge is obtained for a CO2 content between 20 and 30 vol.%.

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

    SciTech Connect

    Tay, W. H.; Kausik, S. S.; Yap, S. L.; Wong, C. S.

    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.

  3. Simulation Tool for Dielectric Barrier Discharge Plasma Actuators

    NASA Technical Reports Server (NTRS)

    Likhanskii, Alexander

    2014-01-01

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

  4. Development of a Lumped Element Circuit Model for Approximation of Dielectric Barrier Discharges

    DTIC Science & Technology

    2011-08-01

    dielectric barrier discharge (DBD) plasmas. Based on experimental observations, it is assumed that nanosecond pulsed DBDs, which have been proposed...species for pulsed direct current (DC) dielectric barrier discharge (DBD) plasmas. Based on experimental observations, it is assumed that nanosecond...momentum-based approaches. Given the fundamental differences between the novel pulsed discharge approach and the more conventional momentum-based

  5. Dielectric barrier discharge processing of aerospace materials

    NASA Astrophysics Data System (ADS)

    Scott, S. J.; Figgures, C. C.; Dixon, D. G.

    2004-08-01

    We report the use of atmospheric pressure, air based, dielectric barrier discharges (DBD) to treat materials commonly used in the aerospace industries. The material samples were processed using a test-bed of a conventional DBD configuration in which the sample formed one of the electrodes and was placed in close proximity to a ceramic electrode. The discharges generated a powerful, cold oxidizing environment which was able to remove organic contaminants, etch primer and paint layers, oxidize aluminium and roughen carbon fibre composites by the selective removal of resin.

  6. Electrodynamic force of dielectric barrier discharge

    SciTech Connect

    Shang, J. S.; Roveda, F.; Huang, P. G.

    2011-06-01

    The periodic electrostatic force of dielectric barrier discharge (DBD) in nitrogen for flow control is investigated by a system of physics-based, two-dimensional model equations. The plasma generation process of DBD is mainly the avalanche growth of electrons through the secondary emission from cathode. Therefore, the charged particle motion of a succession of random micro discharges can be approximated by the drift-diffusion model. The force of DBD generated by charge separation and accumulation over the dielectrics is obtained by solving the model equations with the rigorous media interface boundary condition of Maxwell equations in the time domain. The discharge structure and force components by different electrical permittivity and amplitudes of externally applied electrical potential are delineated and quantified.

  7. Experimental determination of dielectric barrier discharge capacitance

    NASA Astrophysics Data System (ADS)

    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 (Qmax - Vmax 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.

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

    SciTech Connect

    Du, Yinchang; Li, Yangfang; Cao, Jinxiang; Liu, Yu; Wang, Jian; Zheng, Zhe

    2014-06-15

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

  9. Coal Liquefaction by Using Dielectric Barrier Discharge Plasma

    NASA Astrophysics Data System (ADS)

    Wang, Qiuying; Wu, Peng; Gu, Fan

    2013-07-01

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

  10. Roll-to-roll DBD plasma pretreated polyethylene web for enhancement of Al coating adhesion and barrier property

    NASA Astrophysics Data System (ADS)

    Zhang, Haibao; Li, Hua; Fang, Ming; Wang, Zhengduo; Sang, Lijun; Yang, Lizhen; Chen, Qiang

    2016-12-01

    In this paper the roll-to-roll atmospheric dielectric barrier discharge (DBD) was used to pre-treat polyethylene (PE) web surface before the conventional thermal evaporation aluminum (Al) was performed as a barrier layer. We emphasized the plasma environment effect based on the inlet three kinds of reactive monomers. The cross hatch test was employed to assess the Al coating adhesion; and the oxygen transmission rate (OTR) was used to evaluate gas barrier property. The results showed that after roll-to-roll DBD plasma treatment all Al coatings adhered strongly on PE films and were free from pinhole defects with mirror morphology. The OTR was reduced from 2673 cm3/m2 day for Al-coated original PE to 138 cm3/m2 day for Al-coated allyamine (C3H7N) modified PE. To well understand the mechanism the chemical compositions of the untreated and DBD plasma pretreated PE films were analyzed by X-ray photoelectron spectroscopy (XPS). The surface topography was characterized by atomic force microscopy (AFM). For the property of surface energy the water contact angle measurement was also carried out in the DBD plasma treated samples with deionized water.

  11. Transition from symmetric discharge to asymmetric discharge in a short gap helium dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Ning, Wenjun; Dai, Dong; Zhang, YuHui; Hao, Yanpeng; Li, Licheng

    2017-07-01

    The discharge dynamics of a 2.08 mm gap helium dielectric barrier discharge (DBD) are studied with a one-dimensional fluid model. By increasing the amplitude of a sinusoidal voltage source, it is observed that the discharge is symmetric at first and abruptly turns into an asymmetric state after passing a certain critical value. Compared with former publications dealing with relatively larger gap-distance DBD, our simulation results indicate some new discoveries. First, in both the symmetric and asymmetric states, every discharge event is fully developed from Townsend discharge to glow discharge, and the discharge current appears as a steep narrow pulse. Second, the residual positive column is always completely dissipated before the next break down; therefore, its influence on the symmetric-to-asymmetric transition can be eliminated. It is further revealed that the symmetric-to-asymmetric transition in the short-gap DBD is more delicate. A subtle phase shift is observed before the transition process. When the phase shift is further promoted with voltage rising, a discordance of the evolution paces between electron and ions occurs, which consequently leads to the formation of discharge asymmetry.

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

    NASA Astrophysics Data System (ADS)

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

    2017-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2017-04-01

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

  14. Dielectric Barrier Discharges: Pulsed Breakdown, Electrical Characterization and Chemistry

    DTIC Science & Technology

    2013-06-01

    for pulsed driven Dielectric Barrier Discharges ( DBDs ) in particular. Fast electrical, optical and spectroscopic methods enable the study of...ignition, breakdown statistics and spatio- temporally resolved development of pulsed DBD microdischarges. The determination of electrical parameters such...equivalent circuit which is consistent with sinusoidal- voltage driven or miniature pulsed driven DBDs . The characterization of the dominant chemical

  15. Numerical investigation of dielectric barrier discharges

    NASA Astrophysics Data System (ADS)

    Li, Jing

    1997-12-01

    A dielectric barrier discharge (DBD) is a transient discharge occurring between two electrodes in coaxial or planar arrangements separated by one or two layers of dielectric material. The charge accumulated on the dielectric barrier generates a field in a direction opposite to the applied field. The discharge is quenched before an arc is formed. It is one of the few non-thermal discharges that operates at atmospheric pressure and has the potential for use in pollution control. In this work, a numerical model of the dielectric barrier discharge is developed, along with the numerical approach. Adaptive grids based on the charge distribution is used. A self-consistent method is used to solve for the electric field and charge densities. The Successive Overrelaxation (SOR) method in a non-uniform grid spacing is used to solve the Poisson's equation in the cylindrically-symmetric coordinate. The Flux Corrected Transport (FCT) method is modified to solve the continuity equations in the non-uniform grid spacing. Parametric studies of dielectric barrier discharges are conducted. General characteristics of dielectric barrier discharges in both anode-directed and cathode-directed streamer are studied. Effects of the dielectric capacitance, the applied field, the resistance in external circuit and the type of gases (O2, air, N2) are investigated. We conclude that the SOR method in an adaptive grid spacing for the solution of the Poisson's equation in the cylindrically-symmetric coordinate is convergent and effective. The dielectric capacitance has little effect on the g-factor of radical production, but it determines the strength of the dielectric barrier discharge. The applied field and the type of gases used have a significant role on the current peak, current pulse duration and radical generation efficiency, discharge strength, and microstreamer radius, whereas the external series resistance has very little effect on the streamer properties. The results are helpful in

  16. Applications of dielectric barrier discharges

    SciTech Connect

    Falkenstein, Z.

    1998-12-31

    Dielectric barrier discharges (DBDs) in oxygen and air are well established for the production of large quantities of ozone and are more recently being applied to a wider range of plasmachemical processes. Here, the application of DBDs for ozone synthesis, the non-thermal oxidation of volatile organic compounds (VOCs) in air, the generation of incoherent (V)UV radiation and surface processing (etching, ashing) is presented. The main plasmaphysical features of sinusoidally-driven DBDs (transient, filamented, non-thermal plasmas at atmospheric pressure) are described, and a simple plasmachemical reaction pathway for ozone synthesis are give. Experimental results on the degradation of VOCs (2-propanol, trichloroethylene, carbon tetrachloride), as well as byproduct formation is presented for stand-alone DBD treatment, as well as for simultaneous (V)UV illumination of the discharge. Illumination of the discharge with (V)UV can change the plasmachemistry by enhanced formation of certain species of radicals--and thereby change byproduct formation--but also can change the discharge physics, known as the Joshi effect. As an example for generation of excited dimers and exiplexes for the production of incoherent UV light, experimental results on a XeBr* excimer UV light source are presented. Effects of the total and partial pressure of a Xe/Br{sub 2} system, the gap spacing and the applied driving frequency on the UV radiant efficiency are shown. For the application of DBDs for surface processing, experimental results of photoresist ashing on Si wafers using DBDs in oxygen are shown function of gas pressure, gap spacing and applied frequency.

  17. Statistical modelling of discharge behavior of atmospheric pressure dielectric barrier discharge

    SciTech Connect

    Tay, W. H.; Kausik, S. S.; Wong, C. S. Yap, S. L.; Muniandy, S. V.

    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.

  18. Susceptibility constants of airborne bacteria to dielectric barrier discharge for antibacterial performance evaluation.

    PubMed

    Park, Chul Woo; Hwang, Jungho

    2013-01-15

    Dielectric barrier discharge (DBD) is a promising method to remove contaminant bioaerosols. The collection efficiency of a DBD reactor is an important factor for determining a reactor's removal efficiency. Without considering collection, simply defining the inactivation efficiency based on colony counting numbers for DBD as on and off may lead to overestimation of the inactivation efficiency of the DBD reactor. One-pass removal tests of bioaerosols were carried out to deduce the inactivation efficiency of the DBD reactor using both aerosol- and colony-counting methods. Our DBD reactor showed good performance for removing test bioaerosols for an applied voltage of 7.5 kV and a residence time of 0.24s, with η(CFU), η(Number), and η(Inactivation) values of 94%, 64%, and 83%, respectively. Additionally, we introduce the susceptibility constant of bioaerosols to DBD as a quantitative parameter for the performance evaluation of a DBD reactor. The modified susceptibility constant, which is the ratio of the susceptibility constant to the volume of the plasma reactor, has been successfully demonstrated for the performance evaluation of different sized DBD reactors under different DBD operating conditions. Our methodology will be used for design optimization, performance evaluation, and prediction of power consumption of DBD for industrial applications.

  19. Boundary Effect of Planar Glow Dielectric Barrier Discharge and Its Influence on the Discharge Structure

    NASA Astrophysics Data System (ADS)

    Xu, Shaowei; Li, Lulu; Ouyang, Jiting

    2015-05-01

    The dielectric barrier discharge (DBD) in the glow regime in neon has been investigated by experiment and two-dimensional (2D) fluid modeling. The discharge was carried out in a planar DBD system with segmented-electrodes driven by square-wave voltage. The results show that the glow DBD originates in the center of the electrode and expands outward to the electrode edge during each half cycle of the voltage, forming a radial structure. The discharge decays firstly in the inner area but sustains longer in the edge area, showing a reversed discharge area. The discharge cannot completely cover the entire electrode surface, but remains a border of non- or weak discharge. The fluid modeling shows a similar result in agreement with the experiments. The simulations indicate that the electric field in the edge area is distorted due to the boundary effect so that the electric field and charge distribution are different from that in the inner part. The distorted field reduces the longitudinal component near the edge and causes the local field to be lower than that in the center, and hence makes the discharge behindhand. It also induces a transverse field that makes the discharge extend radially outward to the edge. The boundary effect plays an important role in the glow DBD structure. supported by National Natural Science Foundation of China (No. 11175017)

  20. Surface Treatment System Using Dielectric Barrier Discharge

    NASA Astrophysics Data System (ADS)

    Daniels, Ryan; Gershman, Sophia; Faust, Jessica

    2012-10-01

    Atmospheric pressure plasmas have been used recently to improve surface properties of materials. For example, plasma treatment improves wettability, activates and functionalizes the surface of polyethylene making it more suitable for biological applications. We have designed and constructed a system that allows the study of the effect of dielectric barrier discharge (DBD) on the surface properties of treated materials. Preliminary results show that 55 second treatment by the DBD in a 1mm gap reduces the contact angle of polyethylene from 78 +/- 1 before to 40 +/- 1 after the treatment. The DBD is generated using a 15kV, 1kHz pulsed dc power supply a mixture of Ar and O2 as the carrier gas. The study parameters include the ratios of O2 to Ar, the power supply frequency and duty cycle. To perform surface analysis, we have designed a transfer chamber. A bellows drive is used to transport the sample to the mobile transfer chamber and then to a test chamber without exposure to the environment. Plasma treatment improves biological compatibility of polyethylene and makes it suitable for use in implants, prosthetics, and cell cultures.

  1. Effect of volume and surface charges on discharge structure of glow dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Xu, Shao-Wei; He, Feng; Wang, Yu; Li, Lulu; Ouyang, Ji-Ting

    2013-08-01

    The effect of volume and surface charges on the structure of glow dielectric barrier discharge (DBD) has been investigated numerically by using two-dimensional (2D) fluid modeling. The local increase of volume or surface charges induces a kind of activation-inhibition effect, which enhances the local volume discharge and inhibits the discharge in neighborhoods, resulting in non-uniform discharge. The activation-inhibition effect due to the non-uniform volume and/or surface charges depends on the non-uniformity itself and the applied voltage. The activation-inhibition of non-uniform charges has different effects on the volume charges and the accumulated surface charges. The distribution of remaining free charges (seed electrons) in volume at the beginning of voltage pulse plays a key role for the glow DBD structure, resulting in a patterned DBD, when the seed electrons are non-uniform at higher frequency and moderate voltage or uniform DBD, when the seed electrons are uniform at lower frequency or high voltage. The distribution of surface charges is not the determining factor but a result of the formed DBD structure.

  2. Dielectric Barrier Discharge Plasma Actuators with Novel Geometries for Flow Modification: Experimental Measurements and Validation with a 2-D Fluid Model

    DTIC Science & Technology

    2013-12-30

    Dielectric barrier discharge ( DBD ) U U U UU 16 Noah Hershkowitz 608-831-5862 SF-298 Abstract / Contract No. FA9550-10-1-0565 Optical characteristics of...surface dielectric barrier discharge ( DBD ) plasma actuators with wire/planar electrodes were studied using an intensified charge-coupled device camera and...grounded planar electrode were observed for the first time. Time resolved velocity measurements of the air flow fields induced by planar DBD actuators

  3. The Electrical Characteristics of a Filamentary Dielectric Barrier Discharge

    SciTech Connect

    Tay, W. H.; Yap, S. L.; Wong, C. S.

    2010-07-07

    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.

  4. Discharge physics and influence of the modulation on helium DBD modes in the medium-frequency range at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Boisvert, Jean-Sébastien; Margot, Joëlle; Massines, Françoise

    2017-04-01

    In this paper the recently reported hybrid mode (a dielectric barrier discharge (DBD) excited by an electric field oscillating at about 1 MHz) is investigated using space and time-resolved imaging together with electrical measurements. In contrast with the helium low-frequency DBD, at 1.6 MHz the light emission is desynchronized with the discharge current. It rather depends on the enhanced rate of stepwise excitation resulting from the massive secondary emission occurring 0.15Ƭ after the discharge current maximum (Ƭ is the excitation wave period). The consequence of ion impacts on the dielectric surfaces is a higher gas and dielectric temperatures as compared to typical helium DBDs. The electrical behavior and the gas temperature of a pulsed dielectric-barrier discharge operated at 1.6 MHz are also described in this paper as a function of the repetition rate (varying from 1 Hz to 10 kHz). The gas temperature is reduced when repetition rates higher or equal to 10 Hz is used. This is related to the gas renewal rate of 8.3 Hz, i.e., gas residence time of 120 ms in our conditions. In addition, due to the memory effect in the gas, the gas gap voltage decreases as the repetition rate increases. However, beyond 100 Hz, the power decreases and the gas gap voltage increases again. As a consequence, for a given power density, the optimal repetition rate is 100 Hz which minimizes the gas temperature without reducing the power density. Contribution to the topical issue "The 15th International Symposium on High Pressure Low Temperature Plasma Chemistry (HAKONE XV)", edited by Nicolas Gherardi and Tomáš Hoder

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

    NASA Astrophysics Data System (ADS)

    Gadkari, Siddharth; Tu, Xin; Gu, Sai

    2017-09-01

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

  6. Development of a dimensionless parameter for characterization of dielectric barrier discharge devices with respect to geometrical features

    NASA Astrophysics Data System (ADS)

    Lim, Mook Tzeng; Zuklifli, Ahmad Zulazlan Shah; Jayapalan, Kanesh Kumar; Chin, Oihoong

    2017-09-01

    Non-thermal plasma (NTP) devices produce excited and radical species that have higher energy levels than their ground state and are utilized for various applications. There are various types of NTP devices, with dielectric barrier discharge (DBD) reactors being widely used. These DBD devices vary in geometrical configuration and operating parameters, making a comparison of their performance in terms of discharge power characteristics difficult. Therefore, this study proposes a dimensionless parameter that is related to the geometrical features, and is a function of the discharge power with respect to the frequency, voltage, and capacitance of a DBD. The dimensionless parameter, in the form of a ratio of the discharge energy per cycle to the gap capacitive energy, will be useful for engineers and designers to compare the energy characteristics of devices systematically, and could also be used for scaling up DBD devices. From the results in this experiment and from the literature, different DBD devices are categorized into three separate groups according to different levels of the energy ratio. The larger DBD devices have lower energy ratios due to their lower estimated surface discharge areas and capacitive reactance. Therefore, the devices can be categorized according to the energy ratio due to the effects of the geometrical features of the DBD devices, since it affects the surface discharge area and capacitance of the DBD. The DBD devices are also categorized into three separate groups using the Kriegseis factor, but the categorization is different from that of the energy ratio.

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

    NASA Astrophysics Data System (ADS)

    Pal, U. N.; Kumar, M.; Tyagi, M. S.; Meena, B. L.; Khatun, H.; Sharma, A. K.

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

  9. Dielectric Barrier Discharge control on an unstarting supersonic flow

    NASA Astrophysics Data System (ADS)

    Im, Seong-Kyun; Do, Hyungrok; Bak, Moonsoo; Cappelli, Mark

    2011-10-01

    The control of unstarting supersonic model inlet flow using Dielectric Barrier Discharge (DBD) is experimentally demonstrated at Mach 4.7 flow condition. Planar Laser Rayleigh Scattering (PLRS) technique is utilized to visualize important flow features, such as boundary layers and shockwaves, at low static temperature (~60 K) and pressure (~1 kPa) freestream condition. The unstart which is initiated by jet injection in three different model inlet flow, a laminar boundary layer, tripped boundary layer without actuation, and tripped boundary layer with actuation, is demonstrated with PLRS technique. The delay of unstart process is observed through the DBD actuation of the tripped boundary layer when a single DBD actuator pair is oriented parallel to the freestream flow, generates spanwise disturbances. However, this actuation on unstart process is limited to a region of actuation. The control of unstarting supersonic model inlet flow using Dielectric Barrier Discharge (DBD) is experimentally demonstrated at Mach 4.7 flow condition. Planar Laser Rayleigh Scattering (PLRS) technique is utilized to visualize important flow features, such as boundary layers and shockwaves, at low static temperature (~60 K) and pressure (~1 kPa) freestream condition. The unstart which is initiated by jet injection in three different model inlet flow, a laminar boundary layer, tripped boundary layer without actuation, and tripped boundary layer with actuation, is demonstrated with PLRS technique. The delay of unstart process is observed through the DBD actuation of the tripped boundary layer when a single DBD actuator pair is oriented parallel to the freestream flow, generates spanwise disturbances. However, this actuation on unstart process is limited to a region of actuation. This material is based upon work supported by the Department of Energy under Award Number(s)DE-FC52-08NA28614.

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

    NASA Technical Reports Server (NTRS)

    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.

  11. Degradation Of 4-Chlorophenol Using Water Falling Film Dbd Reactor

    NASA Astrophysics Data System (ADS)

    Dojcinovic, B.; Roglic, G.; Obradovic, B. M.; Kuraica, M. M.; Puric, J.; Natic, M.; Tosti, T.; Manojlovic, D.

    2010-07-01

    In this paper we present experimental results of degradation of 4-chlorphenol using falling film dielectric barrier discharge (DBD) reactor. Degradation of 100 ml/L water solution of 4-chlorphenol was examined using catalysts in four different set of conditions: DBD, DBD/H2O2, DBD/TiO2 i DBD/Fe2+. Kinetics of the 4-chlorophenol degrada- tion in several successive passes trough the reactor was monitored using HPLC. Changes in concentrations of carbon that originate from products of degradations like acetic, formic and oxalic acids and changes in concentrations of carbon calculated on basis of degraded 4-chlorophenole are presented.

  12. Morphological and chemical changes of aerosolized E. coli treated with a dielectric barrier discharge.

    PubMed

    Romero-Mangado, Jaione; Nordlund, Dennis; Soberon, Felipe; Deane, Graham; Maughan, Kevin; Sainio, Sami; Singh, Gurusharan; Daniels, Stephen; Saunders, Ian T; Loftus, David; Meyyappan, M; Koehne, Jessica; Gandhiraman, Ram P

    2016-03-12

    This study presents the morphological and chemical modification of the cell structure of aerosolized Escherichia coli treated with a dielectric barrier discharge (DBD). Exposure to DBD results in severe oxidation of the bacteria, leading to the formation of hydroxyl groups and carbonyl groups and a significant reduction in amine functionalities and phosphate groups. Near edge x-ray absorption fine structure (NEXAFS) measurements confirm the presence of additional oxide bonds upon DBD treatment, suggesting oxidation of the outer layer of the cell wall. Electron microscopy images show that the bacteria undergo physical distortion to varying degrees, resulting in deformation of the bacterial structure. The electromagnetic field around the DBD coil causes severe damage to the cell structure, possibly resulting in leakage of vital cellular materials. The oxidation and chemical modification of the bacterial components are evident from the Fourier transform infrared spectroscopy and NEXAFS results. The bacterial reculture experiments confirm inactivation of airborne E. coli upon treating with DBD.

  13. Effect of Dielectric Barrier Discharge Plasma Actuators on Non-equilibrium Hypersonic Flows

    DTIC Science & Technology

    2014-10-28

    alternative, we propose the use of micro- second pulsed Dielectric Barrier Discharge (DBD) plasma actuator7,20–23 for the net reduction of thermal load...include counter-flow plasma jets , energy deposition methods using high energy beams like electron and micro-wave, and gas heating using arc or electric...actuators have been implemented in nanosecond and microsecond pulse widths. Nanosecond pulsed DBD plasma actuators have also been successful in high

  14. Experimental investigation on electrical characteristics and dose measurement of dielectric barrier discharge plasma device used for therapeutic application

    NASA Astrophysics Data System (ADS)

    Shahbazi Rad, Zahra; Abbasi Davani, Fereydoun

    2017-04-01

    In this research, a Dielectric Barrier Discharge (DBD) plasma device operating in air has been made. The electrical characteristics of this device like instantaneous power, dissipated power, and discharge capacitance have been measured. Also, the effects of applied voltage on the dissipated power and discharge capacitance of the device have been investigated. The determination of electrical parameters is important in DBD plasma device used in living tissue treatment for choosing the proper treatment doses and preventing the destructive effects. The non-thermal atmospheric pressure DBD plasma source was applied for studying the acceleration of blood coagulation time, in vitro and wound healing time, in vivo. The citrated blood drops coagulated within 5 s treatment time by DBD plasma. The effects of plasma temperature and electric field on blood coagulation have been studied as an affirmation of the applicability of the constructed device. Also, the effect of constructed DBD plasma on wound healing acceleration has been investigated.

  15. Simulation of DBD plasma actuators, and nanoparticle-plasma interactions in argon-hydrogen CCP RF discharges

    NASA Astrophysics Data System (ADS)

    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

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

    PubMed Central

    Eisenmann, Kathryn M.

    2017-01-01

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

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

    PubMed

    Karki, Surya B; Yildirim-Ayan, Eda; Eisenmann, Kathryn M; Ayan, Halim

    2017-01-01

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

  18. 3D printed electrodes for a dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Albertson, Robert; Gershman, Sophia; Zwicker, Andrew

    2013-10-01

    The affordability and advancements in 3D printing technology make it the method of choice for prototyping and development. We investigate how the thickness and density of 3D printed electrodes affects the formation of microdischarges inside a dielectric barrier discharge (DBD) surface modification reactor. We use a Makerbot Replicator II 3D printer to manufacture the electrodes by encasing thin pieces of copper tape in PLA plastic. The DBD setup consists of a cylindrical aluminum HV electrode which is surrounded by a layer of 5mm thick Alumina and is connected to a 15 kV, 75-300 kHz, AC power supply. The printed electrodes are grounded and held 5mm beneath the Alumina, forming a discharge gap. The DBD is operated with Ar/Air and Ar/O2/Air mixtures at atmospheric pressure. A PI-MAX 3 ICCD camera is used to image the microdischarges at various stages of their development. The image analysis suggests that the printed electrodes with a thicker plastic layer and a greater infill density have more uniform discharges. Quickfield electric field simulations suggest that the field inside the discharge gap is distorted near the surface of the electrodes due to irregularities in the printed material. These results can be used to guide the future design of 3D printed electrical components.

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

    NASA Astrophysics Data System (ADS)

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

    2017-04-01

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

  20. Characteristics of radio-frequency atmospheric pressure dielectric-barrier discharge with dielectric electrodes

    SciTech Connect

    Hussain, S. E-mail: shussainuos@yahoo.com; Qazi, H. I. A.; Badar, M. A.

    2014-03-15

    An experimental investigation to characterize the properties and highlight the benefits of atmospheric pressure radio-frequency dielectric-barrier discharge (rf DBD) with dielectric electrodes fabricated by anodizing aluminium substrate is presented. The current-voltage characteristics and millisecond images are used to distinguish the α and γ modes. This atmospheric rf DBD is observed to retain the discharge volume without constriction in γ mode. Optical emission spectroscopy demonstrates that the large discharge current leads to more abundant reactive species in this plasma source.

  1. Investigation of microscale dielectric barrier discharge plasma devices

    NASA Astrophysics Data System (ADS)

    Zito, Justin C.

    This dissertation presents research performed on reduced-scale dielectric barrier discharge (DBD) plasma actuators. A first generation of microscale DBD actuators are designed and manufactured using polymeric dielectric layers, and successfully demonstrate operation at reduced scales. The actuators are 1 cm long and vary in width from tens of microns to several millimeters. A thin-film polymer or ceramic material is used as the dielectric barrier with thicknesses from 5 to 20 microns. The devices are characterized for their electrical, fluidic and mechanical performance. With electrical input of 5 kVpp, 1 kHz, the microscale DBD actuators induce a wall jet with velocity reaching up to 2 m/s and produce 3.5 mN/m of thrust, while consuming an average power of 20 W/m. A 5 mN/m plasma body force was observed, acting on the surrounding air. Failure of the microscale DBD actuators is investigated using thermal measurements of the dielectric surface in addition to both optical and scanning electron microscopy. The cause of device failure is identified as erosion of the dielectric surface due to collisions with ions from the discharge. A second generation of microscale actuators is then designed and manufactured using a more reliable dielectric material, namely silicon dioxide. These actuators demonstrate a significant improvement in device lifetime compared with first-generation microscale DBD actuators. The increase in actuator lifetime allowed the electrical, fluidic and mechanical characterization to be repeated over several input voltages and frequencies. At 7 kVpp, 1 kHz, the actuators with SiO2 dielectric induced velocities up to 1.5 m/s and demonstrated 1.4 mN/m of thrust while consuming an average power of 41 W/m. The plasma body force reached up to 2.5 mN/m. Depending on electrical input, the induced velocity and thrust span an order of magnitude in range. Comparisons are made with macroscale DBD actuators which relate the actuator's output performance and power

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

    SciTech Connect

    Yang, Aijun; Wang, Xiaohua E-mail: mzrong@mail.xjtu.edu.cn; Liu, Dingxin; Rong, Mingzhe E-mail: mzrong@mail.xjtu.edu.cn; Kong, Michael G.

    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.

  3. Generation of high pressure homogeneous dielectric barrier discharge in air

    NASA Astrophysics Data System (ADS)

    Osawa, Naoki; Takashi, Ami; Yoshioka, Yoshio; Hanaoka, Ryoichi

    2013-02-01

    We succeeded in generating an atmospheric pressure Townsend discharge (APTD) in air by using a simple DBD device that consists of alumina barriers and plane electrodes. So far, we applied the APTD to an ozonizer and found that the ozone generation efficiency was higher by the APTD mode than by the conventional DBD mode in larger specific input energy region. It is well known that an operation under an optimized high gas pressure is advantageous for efficient ozone generation from air. In this paper, we investigated whether the Townsend discharge (TD) in dry air in high pressure up to 0.17 MPa can be generated or not. From the observation results of current waveforms and discharge photographs, we found that (1) the discharge currents flow continuously and have only one peak in every half cycle in all gas pressure and (2) filamentary discharges are not recognized between barriers in all gas pressure. These features completely agree with the features of the APTD we reported. Therefore, we concluded that our TD can be generated even in dry air in the pressure range of 0.1 and 0.17 MPa. Contribution to the Topical Issue "13th International Symposium on High Pressure Low Temperature Plasma Chemistry (Hakone XIII)", Edited by Nicolas Gherardi, Henryca Danuta Stryczewska and Yvan Ségui.

  4. Simulated and experimental studies on the array dielectric barrier discharge of water electrodes

    NASA Astrophysics Data System (ADS)

    Lele, WANG; Xiutao, HUANG; Junfeng, CHEN; Shengming, WANG; Zhaoyang, HU; Minghai, LIU

    2017-03-01

    A kind of dielectric barrier discharge (DBD) device composed of water electrodes with 3 × 3 forms can produce large-area low-temperature plasmas at atmospheric pressure. To reflect the discharge characteristics of DBD better, a dynamic simulation model, which is based on the voltage controlled current source (CCS), is established, then the established model in Matlab/Simulink is used to simulate the DBD in air. The voltage–current waves and Lissajous at a voltage of 10 kV, 11 kV and 12 kV peak value with a frequency of 15 kHz are studied. The change of the discharge power of DBD with a different amplitude and frequency of applied voltage is also analyzed. The result shows the voltage–current waves, Lissajous and discharge power of DBD under different conditions from the simulation agree well with those of the experiment. In addition, we propose a method to calculate the dielectric barrier capacitance {{C}}{{d}} and the gap capacitance {{C}}{{g}}, which is valid through analyzing the variation of capacitance at different voltage amplitudes.

  5. Simulated and experimental studies on the array dielectric barrier discharge of water electrodes

    NASA Astrophysics Data System (ADS)

    Wang, Lele; Huang, Xiutao; Chen, Junfeng; Wang, Shengming; Hu, Zhaoyang; Liu, Minghai

    2017-03-01

    A kind of dielectric barrier discharge (DBD) device composed of water electrodes with 3 × 3 forms can produce large-area low-temperature plasmas at atmospheric pressure. To reflect the discharge characteristics of DBD better, a dynamic simulation model, which is based on the voltage controlled current source (CCS), is established, then the established model in Matlab/Simulink is used to simulate the DBD in air. The voltage-current waves and Lissajous at a voltage of 10 kV, 11 kV and 12 kV peak value with a frequency of 15 kHz are studied. The change of the discharge power of DBD with a different amplitude and frequency of applied voltage is also analyzed. The result shows the voltage-current waves, Lissajous and discharge power of DBD under different conditions from the simulation agree well with those of the experiment. In addition, we propose a method to calculate the dielectric barrier capacitance {{C}}{{d}} and the gap capacitance {{C}}{{g}}, which is valid through analyzing the variation of capacitance at different voltage amplitudes.

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

    NASA Astrophysics Data System (ADS)

    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.

  7. Modeling of dielectric barrier discharge plasma actuators driven by repetitive nanosecond pulses

    SciTech Connect

    Likhanskii, Alexandre V.; Shneider, Mikhail N.; Macheret, Sergey O.; Miles, Richard B.

    2007-07-15

    A detailed physical model for an asymmetric dielectric barrier discharge (DBD) in air driven by repetitive nanosecond voltage pulses is developed. In particular, modeling of DBD with high voltage repetitive negative and positive nanosecond pulses combined with positive dc bias is carried out. Operation at high voltage is compared with operation at low voltage, highlighting the advantage of high voltages, however the effect of backward-directed breakdown in the case of negative pulses results in a decrease of the integral momentum transferred to the gas. The use of positive repetitive pulses with dc bias is demonstrated to be promising for DBD performance improvement. The effects of the voltage waveform not only on force magnitude, but also on the spatial profile of the force, are shown. The crucial role of background photoionization in numerical modeling of ionization waves (streamers) in DBD plasmas is demonstrated.

  8. Stabilization of premixed lean methane-air combustion using dielectric barrier discharge with low pollutant emissions

    NASA Astrophysics Data System (ADS)

    Ono, Ryo; Ogura, Kazuaki; Mogi, Toshio

    2017-09-01

    Catalytic combustion is a promising technology to stabilize lean combustion with low pollutant emissions. Catalytic combustion has been applied to gas turbine combustors; however, some drawbacks of this technology remain to be addressed. In this work, a new concept is demonstrated to overcome the problems of catalytic combustion by using dielectric barrier discharge (DBD) instead of a catalyst. A premixed lean methane-air mixture preheated to 400 °C with an equivalence ratio of 0.45 is flowed through the DBD reactor under atmospheric pressure. Almost complete combustion is achieved with a DBD power of 0.7% of the net calorific value of the mixture. The exhaust emissions are NO = 20 ppm, NO2 = 2 ppm, CO = 2 ppm, and HC \\cong 0 ppm. This work demonstrates that DBD-assisted combustion is a potential alternative to catalytic combustion.

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

    PubMed

    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.

  10. Inactivation of spoilage bacteria in package by dielectric barrier discharge atmospheric cold plasma - treatment time effects

    USDA-ARS?s Scientific Manuscript database

    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 ...

  11. Study Of Sterilization Effect Of Dielectric Barrier Discharge On Eucaryotic Microorganisms

    NASA Astrophysics Data System (ADS)

    Vojkovská, H.; Slámová, J.; Kozáková, Z.; Krcma, F.

    2010-07-01

    The work was focused on studying of the effect of the dielectric barrier discharge (DBD) operating at atmospheric pressure on bioindicator Aspergillus niger. Plasma was generated in nitrogen and argon. Paper and PET-foil were used as the carrying medium. The influence of various working conditions on the efficiency of plasma sterilization was studied. Some partial results are presented.

  12. Dielectric barrier discharge plasma actuator for flow control

    NASA Astrophysics Data System (ADS)

    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. The impacts of magnetic field on repetitive nanosecond pulsed dielectric barrier discharge in air

    NASA Astrophysics Data System (ADS)

    Liu, Yidi; Qi, Haicheng; Fan, Zhihui; Yan, Huijie; Ren, ChunSheng

    2016-11-01

    In this paper, the impacts of the parallel magnetic field on the repetitive nanosecond pulsed dielectric barrier discharge (DBD) are experimentally investigated by optical and electrical measurements. The DBD is generated between two parallel-plate electrodes in the ambient air with the stationary magnetic field on the order of 1 T. The experimental results show that additional microdischarge channels are generated and the photocurrent intensity of the plasma is increased by the magnetic field. The microdischarge channels develop along the magnetic field lines and the diffuse background emission of the discharge is stronger in the DBD with the magnetic field. As the pulse repetition frequency decreases from 1200 Hz to 100 Hz, only the photocurrent intensity of the third discharge that occurred at about 500 ns is noticeably increased by the additional magnetic field. It is believed that the enhancement of the memory effect and the confinement of the magnetic field on electrons are the main reasons.

  14. Production of Ar metastables in a dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Mikheyev, Pavel A.; Han, Jiande; Clark, Amanda; Sanderson, Carl; Heaven, Michael C.

    2017-01-01

    The results of experiments with a dielectric barrier discharge (DBD) are presented, where the production of metastable argon atoms was studied. The recently proposed optically pumped all-rare-gas laser (OPRGL) utilizes metastable atoms of heavier rare gases as lasing species. The required number density of metastables for efficient laser operation is 1012÷1013 cm-3 in an atmospheric pressure of He buffer gas. Recent experiments had shown that such densities are easily produced in a nanosecond pulsed discharge, even at pressures larger than atmospheric, but problems appear when one is trying to produce them in a CW regime. The reason for difficulties in the CW production of metastables at an atmospheric pressure seems to be the low value of the E/N parameter (<5-6 Td). In our experiments a 20 KHz DBD in 2-5% Ar mixture with He at an atmospheric pressure was studied. [Ar(1s5)] number density of the order of 1012 cm-3 was readily achieved. Temporal behavior of [Ar(1s5)] throughout the DBD cycle was obtained. The results demonstrate the feasibility of DBDs for OPRGL development.

  15. How do the barrier thickness and dielectric material influence the filamentary mode and CO2 conversion in a flowing DBD?

    NASA Astrophysics Data System (ADS)

    Ozkan, A.; Dufour, T.; Bogaerts, A.; Reniers, F.

    2016-08-01

    Dielectric barrier discharges (DBDs) are commonly used to generate cold plasmas at atmospheric pressure. Whatever their configuration (tubular or planar), the presence of a dielectric barrier is mandatory to prevent too much charge build up in the plasma and the formation of a thermal arc. In this article, the role of the barrier thickness (2.0, 2.4 and 2.8 mm) and of the kind of dielectric material (alumina, mullite, pyrex, quartz) is investigated on the filamentary behavior in the plasma and on the CO2 conversion in a tubular flowing DBD, by means of mass spectrometry measurements correlated with electrical characterization and IR imaging. Increasing the barrier thickness decreases the capacitance, while preserving the electrical charge. As a result, the voltage over the dielectric increases and a larger number of microdischarges is generated, which enhances the CO2 conversion. Furthermore, changing the dielectric material of the barrier, while keeping the same geometry and dimensions, also affects the CO2 conversion. The highest CO2 conversion and energy efficiency are obtained for quartz and alumina, thus not following the trend of the relative permittivity. From the electrical characterization, we clearly demonstrate that the most important parameters are the somewhat higher effective plasma voltage (yielding a somewhat higher electric field and electron energy in the plasma) for quartz, as well as the higher plasma current (and thus larger electron density) and the larger number of microdischarge filaments (mainly for alumina, but also for quartz). The latter could be correlated to the higher surface roughness for alumina and to the higher voltage over the dielectric for quartz.

  16. Degradation of organic pollutants and microorganisms from wastewater using different dielectric barrier discharge configurations--a critical review.

    PubMed

    Mouele, Emile S Massima; Tijani, Jimoh O; Fatoba, Ojo O; Petrik, Leslie F

    2015-12-01

    The growing global drinking water crisis requires the development of novel advanced, sustainable, and cost-effective water treatment technologies to supplement the existing conventional methods. One such technology is advanced oxidation based on dielectric barrier discharge (DBD). DBD such as single and double planar and single and double cylindrical dielectric barrier configurations have been utilized for efficient degradation of recalcitrant organic pollutants. The overall performance of the different DBD system varies and depends on several factors. Therefore, this review was compiled to give an overview of different DBD configurations vis-a-viz their applications and the in situ mechanism of generation of free reactive species for water and wastewater treatment. Our survey of the literature indicated that application of double cylindrical dielectric barrier configuration represents an ideal and viable route for achieving greater water and wastewater purification efficiency.

  17. Preconcentration and Atomization of Arsane in a Dielectric Barrier Discharge with Detection by Atomic Absorption Spectrometry.

    PubMed

    Novák, Petr; Dědina, Jiří; Kratzer, Jan

    2016-06-07

    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.

  18. Growth Control of Dry Yeast Using Scalable Atmospheric-Pressure Dielectric Barrier Discharge Plasma Irradiation

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

    We have investigated the effects of plasma irradiation on the growth of dry yeast (Saccharomyces cerevisiae) using a scalable atmospheric-pressure dielectric barrier discharge (DBD) device. NO of 380 ppm, NO2 of 10 ppm and O3 of 560 ppm were detected 1 mm below the discharges, which were produced by the DBD plasmas. DBD plasma irradiation of 10 to 100 s enhances the growth of yeast in the lag phase, whereas that of 120 and 150 s suppresses the growth. O3, NO2, photons, and heat generated by the plasma irradiation are not responsible for the growth enhancement of the dry yeast. Plasma etching has little effect on the growth of dry yeast cells. NO plays a key role in the growth enhancement of dry yeast cells.

  19. Portable Dielectric Barrier Discharge-Atomic Emission Spectrometer.

    PubMed

    Li, Na; Wu, Zhongchen; Wang, Yingying; Zhang, Jing; Zhang, Xiangnan; Zhang, Hengnan; Wu, Wenhai; Gao, Jing; Jiang, Jie

    2017-02-21

    This paper describes the first demonstration of a portable dielectric barrier discharge-atomic emission spectrometer (DBD-AES). The instrument primarily consists of a miniature electro-thermal vaporizer (ETV), DBD, and optical signal acquisition units. It weighs only 4.5 kg and is powered by a 24 V DC battery with a maximum power consumption of 37 W. The accompanying software can be operated on a laptop computer. A specially designed quartz tube integrates the ETV unit with the DBD chamber. The effects of experimental parameters were investigated. The limit of detection (LOD) for mercury was 0.4 μg L(-1) (1.2 pg) with a sampling volume of 3 μL. The instrument is applicable for multielement analysis, and the LODs ranged from 0.16 to 11.65 μg L(-1) for Zn, Pb, Ag, Cd, Au, Cu, Mn, Fe, Cr, and As. The instrument was also validated by in-field analysis of seawater samples. The experimental results demonstrated the sensitivity, reliability, and practicality of the instrument.

  20. Improvement of water quality using dielectric barrier discharge plasma

    NASA Astrophysics Data System (ADS)

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

    2017-06-01

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

  1. Determination of bismuth by dielectric barrier discharge atomic absorption spectrometry coupled with hydride generation: method optimization and evaluation of analytical performance.

    PubMed

    Kratzer, Jan; Boušek, Jaroslav; Sturgeon, Ralph E; Mester, Zoltán; Dědina, Jiří

    2014-10-07

    Atomization of bismuth hydride in a 17 W planar quartz dielectric barrier discharge (DBD) atomizer was optimized and the performance of this device compared to that of a conventional quartz tube atomizer (QTA) for atomic absorption spectrometry (AAS). Modification of the inner surface of the DBD atomizer using dimethyldichlorsilane (DMDCS) was essential since it improved sensitivity by a factor of 2-4. Argon, at a flow rate of 125 mL min(-1), was the best DBD discharge gas. Free Bi atoms were also observed in the DBD with nitrogen, hydrogen, and helium discharge gases but not in air. The detection limit for Bi (1.1 ng mL(-1)) is worse than with the QTA (0.16 ng mL(-1) Bi). A poorer detection limit compared to a QTA is a consequence of the shorter optical path of the DBD. Moreover, the lower atomization efficiency and/or faster decay of free atoms in the DBD has to be considered. The performance of the DBD as an atomizer reflects both effects, i.e., atomization efficiency and free atom decay, was estimated to be 65% of that of the externally heated quartz tube atomizer. Nevertheless, this hydride generation DBD-AAS approach can be used for the routine determination of Bi, providing repeatability and accuracy comparable to that reached with a QTA, as demonstrated by analysis of NIST SRM 1643e (trace elements in water). The potential of in-atomizer preconcentration in a DBD atomizer is outlined.

  2. New insight into the residual inactivation of Microcystis aeruginosa by dielectric barrier discharge

    PubMed Central

    Li, Lamei; Zhang, Hong; Huang, Qing

    2015-01-01

    We report the new insight into the dielectric barrier discharge (DBD) induced inactivation of Microcystis aeruginosa, the dominant algae which caused harmful cyanobacterial blooms in many developing countries. In contrast with the previous work, we employed flow cytometry to examine the algal cells, so that we could assess the dead and living cells with more accuracy, and distinguish an intermediate state of algal cells which were verified as apoptotic. Our results showed that the numbers of both dead and apoptotic cells increased with DBD treatment delay time, and hydrogen peroxide produced by DBD was the main reason for the time-delayed inactivation effect. However, apart from the influence of hydrogen peroxide, the DBD-induced initial injures on the algal cells during the discharge period also played a considerable role in the inactivation of the DBD treated cells, as indicated by the measurement of intracellular reactive oxygen species (ROS) inside the algal cells. We therefore propose an effective approach to utilization of non-thermal plasma technique that makes good use of the residual inactivation effect to optimize the experimental conditions in terms of discharge time and delay time, so that more efficient treatment of cyanobacterial blooms can be achieved. PMID:26347270

  3. New insight into the residual inactivation of Microcystis aeruginosa by dielectric barrier discharge.

    PubMed

    Li, Lamei; Zhang, Hong; Huang, Qing

    2015-09-08

    We report the new insight into the dielectric barrier discharge (DBD) induced inactivation of Microcystis aeruginosa, the dominant algae which caused harmful cyanobacterial blooms in many developing countries. In contrast with the previous work, we employed flow cytometry to examine the algal cells, so that we could assess the dead and living cells with more accuracy, and distinguish an intermediate state of algal cells which were verified as apoptotic. Our results showed that the numbers of both dead and apoptotic cells increased with DBD treatment delay time, and hydrogen peroxide produced by DBD was the main reason for the time-delayed inactivation effect. However, apart from the influence of hydrogen peroxide, the DBD-induced initial injures on the algal cells during the discharge period also played a considerable role in the inactivation of the DBD treated cells, as indicated by the measurement of intracellular reactive oxygen species (ROS) inside the algal cells. We therefore propose an effective approach to utilization of non-thermal plasma technique that makes good use of the residual inactivation effect to optimize the experimental conditions in terms of discharge time and delay time, so that more efficient treatment of cyanobacterial blooms can be achieved.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    Di, Lanbo; Zhang, Xiuling; Xu, Zhijian

    2014-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Baldus, Sabrina; Kogelheide, Friederike; Bibinov, Nikita; Stapelmann, Katharina; Awakowicz, Peter

    2015-09-01

    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.

  7. Dielectric barrier discharges in analytical chemistry.

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    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)

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

    NASA Astrophysics Data System (ADS)

    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)

  10. Formation and characteristics of patterns in atmospheric-pressure radio-frequency dielectric barrier discharge plasma

    NASA Astrophysics Data System (ADS)

    Yang, Lizhen; Liu, Zhongwei; Mao, Zhiguo; Li, Sen; Chen, Qiang

    2017-01-01

    The patterns in radio-frequency dielectric barrier discharge (RF DBD) are studied at atmospheric pressure of argon (Ar) or helium (He) mixed with nitrogen (N2) gas. When a small amount of N2 is mixed with He or Ar gas, discharge patterns are formed. In a N2/He gas mixture, besides the filament discharge that forms patterns, a glow background discharge is also observed, whereas only the filament discharge forms patterns in a N2/Ar gas mixture. The resolution of the hexagonal pattern as a function of applied power and gas flow rate is then explored. On the basis of spatial-temporal images taken using an intensified charge-coupled device (ICCD), we find that there is no interleaving of two transient hexagon sublattices in N2/Ar or N2/He plasma in RF DBD patterns, which are totally different from those in which surface charges dominated in the mid-frequency DBD plasma. This supports our hypothesis that the bulk charges dominate the pattern formation in RF DBD.

  11. Uniform dielectric barrier discharge with nanosecond pulse excitation for biomedical applications

    NASA Astrophysics Data System (ADS)

    Ayan, Halim

    For some period of time the use of plasma in medicine has been limited to thermal discharges for cauterization and dissection. The effects of thermal plasma on tissue are entirely related to local heating. Non-thermal plasma, on the other hand, can have many different modes of interaction with tissue. It has been recently demonstrated that direct treatment of smooth surfaces by non-thermal dielectric barrier discharge (DBD) in air is highly effective in killing pathogens. Moreover, DBD can create different sub-lethal and selective effects. These results hold significant promise for medical applications such as sterilization of wound surfaces. However, a typical DBD in air can be highly non-uniform, particularly on topographically non-uniform surfaces such as in most living tissues. This creates significant limitations for use of DBDs in wound care and other biomedical applications. In this thesis, a novel non-thermal plasma system, namely nanosecond-pulsed DBD, has been developed and investigated to address this important limitation. Nanosecond-pulsed DBD is shown to be uniform in air at atmospheric pressure and much more effective in killing bacteria than conventional DBDs, particularly on topographically non-uniform surfaces. Thus, this new plasma system is potentially convenient for in vivo and hospital sterilization cases.

  12. Efficacy of atmospheric pressure dielectric barrier discharge for inactivating airborne pathogens

    DOE PAGES

    Romero-Mangado, Jaione; Dey, Avishek; Diaz-Cartagena, Diana C.; ...

    2017-07-05

    Atmospheric pressure plasmas have gained attention in recent years for several environmental applications. This technology could potentially be used to deactivate airborne microorganisms, surface-bound microorganisms, and biofilms. Here, the authors explore the efficacy of the atmospheric pressure dielectric barrier discharge (DBD) to inactivate airborne Staphylococcus epidermidis and Aspergillus niger that are opportunistic pathogens associated with nosocomial infections. This technology uses air as the source of gas and does not require any process gas such as helium, argon, nitrogen, or hydrogen. Moreover, the effect of DBD was studied on aerosolized S. epidermidis and aerosolized A. niger spores via scanning electron microscopymore » (SEM). The morphology observed on the SEM micrographs showed deformations in the cellular structure of both microorganisms. Cell structure damage upon interaction with the DBD suggests leakage of vital cellular materials, which is a key mechanism for microbial inactivation. The chemical structure of the cell surface of S. epidermidis was also analyzed by near edge x-ray absorption fine structure spectroscopy before and after DBD exposure. Our results from surface analysis revealed that reactive oxygen species from the DBD discharge contributed to alterations on the chemistry of the cell membrane/cell wall of S. epidermidis.« less

  13. Dielectric barrier discharges applied for optical spectrometry

    NASA Astrophysics Data System (ADS)

    Brandt, S.; Schütz, A.; Klute, F. D.; Kratzer, J.; Franzke, J.

    2016-09-01

    The present review reflects the importance of dielectric barrier discharges for optical spectrometric detection in analytical chemistry. In contrast to usual discharges with a direct current the electrodes are separated by at least one dielectric barrier. There are two main features of the dielectric barrier discharges: they can serve as dissociation and excitation devices as well as ionization sources, respectively. This article portrays various application fields of dielectric barrier discharges in analytical chemistry used for elemental and molecular detection with optical spectrometry.

  14. Methane conversion using a dielectric barrier discharge reactor at atmospheric pressure for hydrogen production

    NASA Astrophysics Data System (ADS)

    Khadir, N.; Khodja, K.; Belasri, A.

    2017-09-01

    In the present paper, we carried out a theoretical study of dielectric barrier discharge (DBD) filled with pure methane gas. The homogeneous discharge model used in this work includes a plasma chemistry unit, an electrical circuit, and the Boltzmann equation. The model was applied to the case of a sinusoidal voltage at a period frequency of 50 kHz and under a gas pressure of 600 Torr. We investigated the temporal variation of electrical and kinetic discharge parameters such as plasma and dielectric voltages, the discharge current density, electric field, deposited power density, and the species concentration. We also checked the physical model validity by comparing its results with experimental work. According to the results discussed herein, the dielectric capacitance is the parameter that has the greatest effect on the methane conversion and H2/CH4 ratio. This work enriches the knowledge for the improvement of DBD for CH4 conversion and hydrogen production.

  15. Electrical model of dielectric barrier discharge homogenous and filamentary modes

    NASA Astrophysics Data System (ADS)

    López-Fernandez, J. A.; Peña-Eguiluz, R.; López-Callejas, R.; Mercado-Cabrera, A.; Valencia-Alvarado, R.; Muñoz-Castro, A.; Rodríguez-Méndez, B. G.

    2017-01-01

    This work proposes an electrical model that combines homogeneous and filamentary modes of an atmospheric pressure dielectric barrier discharge cell. A voltage controlled electric current source has been utilized to implement the power law equation that represents the homogeneous discharge mode, which starts when the gas breakdown voltage is reached. The filamentary mode implies the emergence of electric current conducting channels (microdischarges), to add this phenomenon an RC circuit commutated by an ideal switch has been proposed. The switch activation occurs at a higher voltage level than the gas breakdown voltage because it is necessary to impose a huge electric field that contributes to the appearance of streamers. The model allows the estimation of several electric parameters inside the reactor that cannot be measured. Also, it is possible to appreciate the modes of the DBD depending on the applied voltage magnitude. Finally, it has been recognized a good agreement between simulation outcomes and experimental results.

  16. The effect of jet and DBD plasma on NCI-78 blood cancer cells

    NASA Astrophysics Data System (ADS)

    Kaushik, Nagendra K.; Kaushik, Neha; Choi, Eun Ha

    2013-06-01

    In this study we describe the effects of a nonthermal jet and dielectric barrier discharge (DBD) plasma on the T98G brain cancer cell line. The results of this study reveal that the jet and DBD plasma inhibits NCI-78 blood cancer cells growth efficiently with the loss of metabolic viability of cells. The main goal of this study is to induce cell death in NCI-78 blood cancer cells by the toxic effect of jet and DBD plasma.

  17. Fluorescence measurement of atomic oxygen concentration in a dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Dvořák, P.; Mrkvičková, M.; Obrusník, A.; Kratzer, J.; Dědina, J.; Procházka, V.

    2017-06-01

    Concentration of atomic oxygen was measured in a volume dielectric barrier discharge (DBD) ignited in mixtures of Ar + O2(+ H2) at atmospheric pressure. Two-photon absorption laser induced fluorescence (TALIF) of atomic oxygen was used and this method was calibrated by TALIF of Xe in a mixture of argon and a trace of xenon. The calibration was performed at atmospheric pressure and it was shown that quenching by three-body collisions has negligible effect on the life time of excited Xe atoms. The concentration of atomic oxygen in the DBD was around 1021 m-3 and it was stable during the whole discharge period. The concentration did not depend much on the electric power delivered to the discharge provided that the power was sufficiently high so that the visible discharge filled the whole reactor volume. Both the addition of hydrogen or replacing of argon by helium led to a significant decrease of atomic oxygen concentration. The TALIF measurements of O concentration levels in the DBD plasma performed in this work are made use of e.g. in the field analytical chemistry. The results contribute to understanding the processes of analyte hydride preconcentration and subsequent atomization in the field of trace element analysis where DBD plasma atomizers are employed.

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

    NASA Astrophysics Data System (ADS)

    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.

  19. Mesoporous TiO2 films fabricated using atmospheric pressure dielectric barrier discharge jet.

    PubMed

    Seo, Hyung-Kee; Elliott, C Michael; Shin, Hyung-Shik

    2010-12-01

    TiO2 nanoparticles were synthesized by a facile method of dielectric barrier discharge jet (DBD jet) for the dye-sensitized solar cell (DSSC) and other potential applications. DBD jet is utilized as a method for deposition of TiO2 nanoparticles with a 9 μm/min growth rate which is more than ×25 faster than reported previously. Their performance was compared with cells fabricated using commercial TiO2 nanoparticles (P25). The crystallinity and chemical bonding states of samples were characterized by XRD and XPS. Photoanodes fabricated by the DBD jet method resulted in approximately 50% higher photoconversion efficiency than ones prepared from P25 nanoparticles.

  20. Design of experiment analysis of CO2 dielectric barrier discharge conditions on CO production

    NASA Astrophysics Data System (ADS)

    Becker, Markus; Ponduri, Srinath; Engeln, Richard; van de Sanden, Richard; Loffhagen, Detlef

    2016-09-01

    Dielectric barrier discharges (DBD) are frequently used for the generation of CO from CO2 which is of particular interest for syngas production. It has been found by means of fluid modelling in that the CO2 conversion frequency in a CO2 DBD depends linearly on the specific energy input (SEI) while the energy efficiency of CO production is only weakly dependent on the SEI. Here, the same numerical model as in is applied to study systematically the influence of gas pressure, applied voltage amplitude and frequency on the CO2 conversion frequency and the energy efficiency of CO production based on a 2-level 3-factor full factorial experimental design. It is found that the operating conditions of the CO2 DBD for CO production can be chosen to either have an optimal throughput or a better energy efficiency. This work was partly supported by the German Research Foundation within the Collaborative Research Centre Transregio 24.

  1. The Effect of Air Plasma on Sterilization of Escherichia coli in Dielectric Barrier Discharge

    NASA Astrophysics Data System (ADS)

    Hu, Miao; Guo, Yun

    2012-08-01

    In this work, a Dielectric Barrier Discharge (DBD) air plasma was used to sterilize Escherichia coli (E. coli) on the surface of medical Polyethylene Terephthalate (PET) film. The leakage of cellular DNA and protein by optical absorbance measurement at 260 nm and 280 nm, together with transmission electron microscopy (TEM) about cell morphology were performed after sterilization to analyse inactivation mechanisms. The results indicated that the DBD air plasma was very effective in E. coli sterilization. The plasma germicidal efficiency depended on the plasma treatment time, the air-gap distance, and the applied voltage. Within 5 min of plasma treatment, the germicidal efficiency against E. coli could reach 99.99%. An etching action on cell membranes by electrons, ions and radicals is the primary mechanism for DBD air plasma sterilization, which leads to the effusion of cellular contents (DNA and protein) and bacterial death.

  2. Transition from diffuse to self-organized discharge in a high frequency dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Belinger, Antoine; Naudé, Nicolas; Gherardi, Nicolas

    2017-05-01

    Depending on the operating conditions, different regimes can be obtained in a dielectric barrier discharge (DBD): filamentary, diffuse (also called homogeneous) or self-organized. For a plane-to-plane DBD operated at high frequency (160 kHz) and at atmospheric pressure in helium gas, we show that the addition of a small amount of nitrogen induces a transition from the diffuse regime to a self-organized regime characterized by the appearance of filaments at the exit of the discharge. In this paper, we detail mechanisms that could be responsible of the transition from diffuse mode to this self-organized mode. We point out the critical role of the power supply and the importance of the gas memory effect from one discharge to the following one on the transition to the self-organised mode. The self-organized mode is usually attributed to a surface memory effect. In this work, we show an additional involvement of the gas memory effect on the self-organized mode. Contribution to the topical issue "The 15th International Symposium on High Pressure Low Temperature Plasma Chemistry (HAKONE XV)", edited by Nicolas Gherardi and Tomáš Hoder

  3. Generation of H2O-ice dielectric barrier discharge for the development of novel cryogenic reaction fields

    NASA Astrophysics Data System (ADS)

    Sakakibara, Noritaka; Terashima, Kazuo

    2017-06-01

    We generated H2O-ice dielectric barrier discharge (DBD), which has H2O ice as a dielectric barrier, at a wide range of cryogenic temperatures down to 6.5 K, and controlled plasma gas temperature as a control parameter. H2O-ice DBD exhibited variations in optical emissions and transition of discharge modes with changing plasma gas temperature. Furthermore, H2O-ice DBD is revealed to be anticipated to have sufficient reactivity as a reaction field on the ice surface in comparison with ultraviolet irradiated chemical reactions such as formation of amino acids. This study is the first report on gas temperature-controlled plasma generation coexistent with H2O ice, focusing on plasma gas temperature as a control parameter.

  4. Effects of airflow on the distribution of filaments in atmospheric AC dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

    Atmospheric-pressure dielectric barrier discharge (DBD) accompanied by airflow has attracted a significant attention for its extensive applications. In this paper, the effects of airflow on the characteristics of the atmospheric air DBD plasma are experimentally investigated using the DBD reactor excited by a 15 kHz AC power source. In order to study the discharge filaments distribution at different flow rates, transparent conductive indium tin oxide film is used as the upper electrode, and quartz glasses are used as insulated dielectrics. Experiment results prove that the breakdown voltage is decreased and more current pulses with declined amplitudes are produced when the airflow is introduced into the discharge gap. It is confirmed that although the discharge seems to be diffuse in the presence of airflow to the naked eyes, the discharge mode remains filamentary in the intensified charge-coupled device images within a single AC cycle. By acquiring the images with a different exposure time, it can be recognized that the discharge filaments move along the flow field direction with a velocity less than the corresponding flow rate. The movement of discharge filaments is attributed to the motion of the charge induced by the airflow.

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

    PubMed

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

    2016-05-01

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

  6. Rapid removal of bacterial endotoxin and natural organic matter in water by dielectric barrier discharge plasma: Efficiency and toxicity assessment.

    PubMed

    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.

  7. Comparing investigation of pattern formation in glow and streamer DBD

    NASA Astrophysics Data System (ADS)

    Li, Ben; Ouyang, Jiting

    2016-11-01

    In this paper, we investigate the behaviors of patterns in dielectric barrier discharge (DBD) in glow and streamer regimes under different operating conditions (driving frequency and voltage) and external electric/magnetic field to explore the similarity and difference of pattern formation. It is found that patterns in both glow and streamer DBDs can be homogenized by decreasing the driving frequency to a low level. But filamentary streamers can still appear at low frequency when the voltage is much higher. With an additional lateral electric field, patterns in both regimes can be homogenized. However, an axial magnetic field makes the glow DBD homogeneous, while the streamer DBD decreases in filamentary size. In both regimes, dynamics and distribution of the space charges, rather than the surface charges, play the predominant role in the formation of DBD patterns. But the surface charges may also play an important role in pattern formation, especially in streamer DBD.

  8. Simulation of Flow Around Cylinder Actuated by DBD Plasma

    NASA Astrophysics Data System (ADS)

    Wang, Yuling; Gao, Chao; Wu, Bin; Hu, Xu

    2016-07-01

    The electric-static body force model is obtained by solving Maxwell's electromagnetic equations. Based on the electro-static model, numerical modeling of flow around a cylinder with a dielectric barrier discharge (DBD) plasma effect is also presented. The flow streamlines between the numerical simulation and the particle image velocimetry (PIV) experiment are consistent. According to the numerical simulation, DBD plasma can reduce the drag coefficient and change the vortex shedding frequencies of flow around the cylinder.

  9. Morphological and chemical changes of aerosolized E. coli treated with a dielectric barrier discharge

    DOE PAGES

    Romero-Mangado, Jaione; Nordlund, Dennis; Soberon, Felipe; ...

    2016-02-12

    This paper presents the morphological and chemical modification of the cell structure of aerosolized Escherichia coli treated with a dielectric barrier discharge (DBD). Exposure to DBD results in severe oxidation of the bacteria, leading to the formation of hydroxyl groups and carbonyl groups and a significant reduction in amine functionalities and phosphate groups. Near edge x-ray absorption fine structure(NEXAFS) measurements confirm the presence of additional oxide bonds upon DBD treatment, suggesting oxidation of the outer layer of the cell wall. Electron microscopy images show that the bacteria undergo physical distortion to varying degrees, resulting in deformation of the bacterial structure.more » The electromagnetic field around the DBD coil causes severe damage to the cell structure, possibly resulting in leakage of vital cellular materials. The oxidation and chemical modification of the bacterial components are evident from the Fourier transform infrared spectroscopy and NEXAFS results. The bacterial reculture experiments confirm inactivation of airborne E. coli upon treating with DBD.« less

  10. Atomization of Bismuthane in a Dielectric Barrier Discharge: A Mechanistic Study.

    PubMed

    Kratzer, Jan; Zelina, Ondřej; Svoboda, Milan; Sturgeon, Ralph E; Mester, Zoltán; Dědina, Jiří

    2016-02-02

    Atomization of bismuthane in a planar dielectric barrier discharge (DBD) atomizer was investigated using a variety of probes, including atomic absorption spectrometry (AAS) to monitor distribution of free atoms along the optical path and direct analysis in real time (DART) coupled to an Orbitrap mass spectrometer to identify the structure of the species arising from the hydride generator as well as the atomizer. Results obtained with the DBD were compared to those from a conventional externally heated quartz tube atomizer (QTA). Free Bi atoms were essentially absent outside the central part of the DBD atomizer, suggesting their high reactivity. The gas phase analyte fraction transported beyond the confines of the DBD or QTA atomizers, quantified by inductively coupled plasma mass spectrometry (ICP-MS), was less than 10%. The amount of Bi found in acidic leachates of the interiors of both atomizers, representing the fraction retained on their surfaces, was ca. 90%. These complementary experiments comprising the determination of recovered Bi in the nitric acid leachates from deposition in the atomizer on the one hand and quantification of the Bi fraction transportable outside the atomizer on the other, were in excellent agreement, providing 100% mass balance of detected analyte. The high fraction of Bi deposited in the atomizers indicates significant reactivity of free Bi atoms, which is in accord with the fact that almost no free Bi atoms exist beyond the physical boundaries of the DBD. The extent of interference from other hydride forming elements (As, Sb, Se) on Bi response by AAS using DBD and QTA atomizers was investigated, with the former atomizer providing superior performance. Compared to QTA, DBD provided 2 orders of magnitude and 1 order of magnitude, respectively, better resistance to interference from Se and Sb.

  11. Pattern formation based on complex coupling mechanism in dielectric barrier discharge

    SciTech Connect

    Liu, Weibo; Dong, Lifang E-mail: pyy1616@163.com; Wang, Yongjie; Zhang, Hao; Pan, Yuyang E-mail: pyy1616@163.com

    2016-08-15

    The pattern formation of cinque-dice square superlattice pattern (CDSSP) is investigated based on the complex coupling mechanism in a dielectric barrier discharge (DBD) system. The spatio-temporal structure of CDSSP obtained by using an intensified-charge coupled device indicates that CDSSP is an interleaving of two kinds of subpatterns (mixture of rectangle and square, and dot-line square) which discharge twice in one half voltage, respectively. Selected by the complex coupling of two subpatterns, the CDSSP can be formed and shows good stability. This investigation based on gas discharge theory together with nonlinear theory may provide a deeper understanding for the nonlinear characteristics and even the formation mechanism of patterns in DBD.

  12. Degradation of selected organophosphate pesticides in wastewater by dielectric barrier discharge plasma.

    PubMed

    Hu, Yingmei; Bai, Yanhong; Yu, Hu; Zhang, Chunhong; Chen, Jierong

    2013-09-01

    In this paper, degradation of selected organophosphate pesticides (dichlorvos and dimethoate) in wastewater by dielectric barrier discharge plasma (DBD) was studied. DBD parameters, i.e. discharge powers and air-gap distances, differently affect their degradation efficiency. The results show that better degradation efficiency is obtained with a higher discharge power and a shorter air-gap distance. The effect of radical intervention degradation was also investigated by adding radical scavenger (tert-butyl alcohol) to the pesticide solution during the experiments. The result shows that the degradation efficiency is restrained in the presence of radical scavenger. It clearly demonstrates that hydroxyl radicals are most likely the main driver for degradation process. Moreover, the kinetics indicate that the disappearance rate of pesticides follows the first-order rate law when the initial concentration of the solution is low, but shifts to zero-order at a higher initial concentration.

  13. Pattern formation based on complex coupling mechanism in dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Liu, Weibo; Dong, Lifang; Wang, Yongjie; Zhang, Hao; Pan, Yuyang

    2016-08-01

    The pattern formation of cinque-dice square superlattice pattern (CDSSP) is investigated based on the complex coupling mechanism in a dielectric barrier discharge (DBD) system. The spatio-temporal structure of CDSSP obtained by using an intensified-charge coupled device indicates that CDSSP is an interleaving of two kinds of subpatterns (mixture of rectangle and square, and dot-line square) which discharge twice in one half voltage, respectively. Selected by the complex coupling of two subpatterns, the CDSSP can be formed and shows good stability. This investigation based on gas discharge theory together with nonlinear theory may provide a deeper understanding for the nonlinear characteristics and even the formation mechanism of patterns in DBD.

  14. Single and multiple streamer DBD micro-discharges for testing inactivation of biologically contaminated surfaces

    NASA Astrophysics Data System (ADS)

    Prukner, Vaclav; Dolezalova, Eva; Simek, Milan

    2014-10-01

    Highly reactive environment produced by atmospheric-pressure, non-equilibrium plasmas generated by surface dielectric barrier discharges (SDBDs) may be used for inactivation of biologically contaminated surfaces. We investigated decontamination efficiency of reactive environment produced by single/multiple surface streamer micro-discharge driven by amplitude-modulated AC power in coplanar electrode geometry on biologically contaminated surface by Escherichia coli. The discharges were fed by synthetic air with water vapor admixtures at atmospheric pressure, time of treatment was set from 10 second to 10 minutes, diameters of used SDBD electrodes (single and multiple streamer) and homogeneously contaminated disc samples were equal (25 mm), the distance between the electrode and contaminated surface was 2 mm. Both a conventional cultivation and fluorescent method LIVE/DEAD Bacterial Viability kit were applied to estimate counts of bacteria after the plasma treatment. Inactivation was effective and bacteria partly lost ability to grow and became injured and viable/active but non-cultivable (VBNC/ABNC). Work was supported by the MEYS under Project LD13010, VES13 COST CZ (COST Action MP 1101).

  15. Microplasma source based on a dielectric barrier discharge for the determination of mercury by atomic emission spectrometry.

    PubMed

    Zhu, Zhenli; Chan, George C-Y; Ray, Steven J; Zhang, Xinrong; Hieftje, Gary M

    2008-11-15

    A low-power, atmospheric-pressure microplasma source based on a dielectric barrier discharge (DBD) has been developed for use in atomic emission spectrometry. The small plasma (0.6 mm x 1 mm x 10 mm) is generated within a glass cell by using electrodes that do not contact the plasma. Powered by an inexpensive ozone generator, the discharge ignites spontaneously, can be easily sustained in Ar or He at gas flow rates ranging from 5 to 200 mL min(-1), and requires less than 1 W of power. The effect of operating parameters such as plasma gas identity, plasma gas flow rate, and residual water vapor on the DBD source performance has been investigated. The plasma can be operated without removal of residual water vapor, permitting it to be directly coupled with cold vapor generation sample introduction. The spectral background of the source is quite clean in the range from 200 to 260 nm with low continuum and structured components. The DBD source has been applied to the determination of Hg by continuous-flow, cold vapor generation and offers detection limits from 14 (He-DBD) to 43 pg mL(-1) (Ar-DBD) without removal of the residual moisture. The use of flow injection with the He-DBD permits measurement of Hg with a 7.2 pg limit of detection, and with repetitive injections having an RSD of <2% for a 10 ng mL(-1) standard.

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

  17. Decomposition of dimethylamine gas with dielectric barrier discharge.

    PubMed

    Ye, Zhaolian; Zhao, Jie; Huang, Hong ying; Ma, Fei; Zhang, Renxi

    2013-09-15

    The decomposition of dimethylamine (DMA) with gas under high flow rate was investigated with dielectric barrier discharge (DBD) technology. Different parameters including removal efficiency, energy yield, carbon balance and CO2 selectivity, secondary products, as well as pathways and mechanisms of DMA degradation were studied. The experimental results showed that removal efficiency of DMA depended on applied voltage and gas flow rate, but had no obvious correlation with initial concentration. Excellent energy performance was obtained using present DBD technology for DMA abatement. When experiment conditions were controlled at: gas flow rate of 14.9 m(3)/h, initial concentration of 2104 mg/m(3), applied voltage of 4.8 kV, removal efficiency of DMA and energy yield can reach 85.2% and 953.9 g/kWh, respectively. However, carbon balance (around 40%) was not ideal due to shorter residence time (about 0.1s), implying that some additional conditions should be considered to improve the total oxidation of DMA. Moreover, secondary products in outlet gas stream were detected via gas chromatogram-mass spectrum and the amounts of NO3(-) and NO2(-) were analyzed by ion chromatogram. The obtained data demonstrated that NOx might be suppressed due to reductive NH radical form DMA dissociation. The likely reaction pathways and mechanisms for the removal of DMA were suggested based on products analysis. Experimental results demonstrated the application potential of DBD as a clean technology for organic nitrogen-containing gas elimination from gas streams. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. Force Measurements of Single and Double Barrier DBD Plasma Actuators in Quiescent Air

    NASA Technical Reports Server (NTRS)

    Hoskinson, Alan R.; Hershkowitz, Noah; Ashpis, David E.

    2008-01-01

    We have performed measurements of the force induced by both single (one electrode insulated) and double (both electrodes insulated) dielectric barrier discharge plasma actuators in quiescent air. We have shown that, for single barrier actuators, as the electrode diameter decreased below those values previously studied the induced Force increases exponentially rather than linearly. This behavior has been experimentally verified using two different measurement techniques: stagnation probe measurements of the induced flow velocity and direct measurement of the force using an electronic balance. In addition, we have shown the the induced force is independent of the material used for the exposed electrode. The same techniques have shown that the induced force of a double barrier actuator increases with decreasing narrow electrode diameter.

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

    NASA Astrophysics Data System (ADS)

    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.

  20. Uniform and non-uniform modes of nanosecond-pulsed dielectric barrier discharge in atmospheric air: fast imaging and spectroscopic measurements of electric field

    PubMed Central

    Liu, Chong; Dobrynin, Danil; Fridman, Alexander

    2014-01-01

    In this study, we report experimental results on fast ICCD imaging of development of nanosecond-pulsed dielectric barrier discharge (DBD) in atmospheric air and spectroscopic measurements of electric field in the discharge. Uniformity of the discharge images obtained with nanosecond exposure times were analyzed using chi-square test. The results indicate that DBD uniformity strongly depends on applied (global) electric field in the discharge gap, and is a threshold phenomenon. We show that in the case of strong overvoltage on the discharge gap (provided by fast rise times), there is transition from filamentary to uniform DBD mode which correlates to the corresponding decrease of maximum local electric field in the discharge. PMID:25071294

  1. Transition from Townsend to radio-frequency homogeneous dielectric barrier discharge in a roll-to-roll configuration

    SciTech Connect

    Bazinette, R.; Paillol, J.; Massines, F.

    2016-06-28

    The aim of this paper is to better understand the transition from Townsend to radio-frequency homogeneous dielectric barrier discharge (DBD) at atmospheric pressure. The study is done in an Ar/NH{sub 3} Penning mixture for an electrode configuration adapted to roll-to-roll plasma surface treatment. The study was led in a frequency range running from 50 kHz up to 8.3 MHz leading to different DBD modes with a 1 mm gas gap: Glow (GDBD), Townsend (TDBD), and Radio-frequency (RF-DBD). In the frequency range between TDBD and RF-DBD, from 250 kHz to 2.3 MHz, additional discharges are observed outside the inter-electrode gas gap. Because each high voltage electrode are inside a dielectric barrel, these additional discharges occur on the side of the barrel where the gap is larger. They disappear when the RF-DBD mode is attained in the 1 mm inter-electrode gas gap, i.e., for frequencies equal or higher than 3 MHz. Fast imaging and optical emission spectroscopy show that the additional discharges are radio-frequency DBDs while the inter-electrode discharge is a TDBD. The RF-DBD discharge mode is attained when electrons drift becomes low enough compared to the voltage oscillation frequency to limit electron loss at the anode. To check that the additional discharges are due to a larger gas gap and a lower voltage amplitude, the TDBD/RF-DBD transition is investigated as a function of the gas gap and the applied voltage frequency and amplitude. Results show that the increase in the frequency at constant gas gap or in the gas gap at constant frequency allows to obtain RF-DBD instead of TDBD. At low frequency and large gap, the increase in the applied voltage allows RF-DBD/TDBD transition. As a consequence, an electrode configuration allowing different gap values is a solution to successively have different discharge modes with the same applied voltage.

  2. Applications of dielectric barrier discharges

    SciTech Connect

    Falkenstein, Z.

    1998-12-01

    Dielectric barrier discharges (DBDs) in oxygen and air are well established for the production of large quantities of ozone and are more recently being applied to a wider range of plasmachemical processes. As an introduction of this type of gas discharge, the main plasmaphysical features of sinusoidal-driven DBDs (transient, non-thermal plasmas at atmospheric pressure) will be described, and plasmachemical reaction pathways for the generation of ozone will be briefly discussed. The generation of atomic oxygen for ozone synthesis leads inevitably to the second application of DBDs, the non-thermal oxidation of volatile organic compounds (VOCs) in dry and humid air. Another application of DBDs is the generation of excited dimers and exiplexes for the production of incoherent (V)UV/visible light. The last and latest application of DBDs is the surface processing near atmospheric pressures. As an example, results of photoresist ashing on Si wafers in an oxygen plasma will be shown as function of gas pressure, gap spacing, and applied frequency. The surface of the etched photoresist is characterized by profilometry and scanning electron microscopy (SEM). The possibility of material deposition with DBDs will also be presented, where DBDs in acetylene lead to fast substrate deposition. Here, only the effects of the gas pressure and gap distance are explored.

  3. Experimental study on temperature characteristics and energy conversion in packed bed reactor with dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Li, Sen; Tang, Zuchen; Gu, Fan

    2010-10-01

    The temperature characteristics and energy conversion in packed bed reactor combined with a dielectric barrier discharge (DBD) plasma was investigated experimentally. The pellet temperatures of two types packed bed reactor, cylindrical reactor and parallel-plate reactor, was measured in conditions of various inlet voltage of DBD plasma. The relationship between pellet temperature of the packed bed and applied voltage of DBD plasma was discovered. The experimental result indicates a tendency that the pellet temperature of packed bed increases as the applied voltage of inlet plasma increases. When the voltage of inlet plasma is high enough, the pellet temperature increment decreases. Simultaneously,the packed bed temperature is sensitive to the inlet plasma energy and there is a potential application to heat exchanger. Moreover the proportion of energy consumption of plasma inputting into packed bed reactor was analyzed and calculated. The mechanisms that electrical energy of inlet plasma is transformed into heat energy in the two phases, gaseous and pellets of the packed bed reactor are different. The energy consumption in pellet phase is dielectric polarization loss and depends on packed bed geometry and DBD plasma etc. The energy consumption in gaseous phase is plasma sheath procedure. The important factors effecting on gas discharge are gaseous component and voltage, frequency of power.

  4. A Novel Generation Method of Dielectric Barrier Discharge and Ozone Production Using a Piezoelectric Transformer

    NASA Astrophysics Data System (ADS)

    Teranishi, Kenji; Suzuki, Susumu; Itoh, Haruo

    2004-09-01

    A novel generation method of a dielectric barrier discharge (DBD) using a piezoelectric transformer (PT) is proposed. Spatio-temporal variations of microdischarges were investigated and discussed on the basis of the observations using a charge-coupled device (CCD) camera. As an example of a practical application of the DBD to a plasma reactor, an ozonizer using the PT was developed and ozone productions were performed in air and oxygen. Maximum ozone concentrations of 3.38 and 20.3 g/Nm3 were obtained in air and oxygen, respectively. The ozonizer can be designed in a compact configuration and driven with low applied voltages because the PT serves as both a high-voltage generator and a discharge electrode.

  5. Simulation Tool for Dielectric Barrier Discharge Plasma Actuators at Atmospheric and Sub-Atmospheric Pressures: SBIR Phase I Final Report

    NASA Technical Reports Server (NTRS)

    Likhanskii, Alexandre

    2012-01-01

    This report is the final report of a SBIR Phase I project. It is identical to the final report submitted, after some proprietary information of administrative nature has been removed. The development of a numerical simulation tool for dielectric barrier discharge (DBD) plasma actuator is reported. The objectives of the project were to analyze and predict DBD operation at wide range of ambient gas pressures. It overcomes the limitations of traditional DBD codes which are limited to low-speed applications and have weak prediction capabilities. The software tool allows DBD actuator analysis and prediction for subsonic to hypersonic flow regime. The simulation tool is based on the VORPAL code developed by Tech-X Corporation. VORPAL's capability of modeling DBD plasma actuator at low pressures (0.1 to 10 torr) using kinetic plasma modeling approach, and at moderate to atmospheric pressures (1 to 10 atm) using hydrodynamic plasma modeling approach, were demonstrated. In addition, results of experiments with pulsed+bias DBD configuration that were performed for validation purposes are reported.

  6. Dielectric Barrier Discharge Plasma Actuator for Flow Control

    NASA Technical Reports Server (NTRS)

    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.

  7. Removal of cyanobacteria from synthetic and real water by dielectric barrier discharge process.

    PubMed

    Zhang, Yi; Chew, Stephanie Ting Yu; Te, Shu Harn; Lim, Tuti Mariana

    2015-12-01

    The feasibility of cyanobacteria removal from freshwater by a dielectric barrier discharge (DBD) process is investigated. Seven commercial and environmental cyanobacteria strains, as well as real algae-laden water, were tested. The removal of the cyanobacteria was evaluated by analyzing the changes in chlorophyll a content, total organic carbon (TOC) concentration, and cell morphology. Nearly total removal of chlorophyll a was achieved within 20 min, while the TOC analysis exhibited an increase-decrease-increase trend in 60 min of treatment, likely due to the oxidation of intracellular and intercellular materials. Observation under light microscopy revealed the disruption of intracellular and intercellular structures within 5 min of DBD treatment and thus supported the TOC analysis. Increasing the salinity of the medium from 0 to 5 parts per thousand (ppt) improved treatment efficiency, where similar level of chlorophyll a removal (around 93%) was achieved in only half the treatment time. Application of DBD on real algae-laden water from a fish farm yielded higher treatment efficiency than in synthetic medium, indicating the promising application of DBD as a means to control cyanobacteria bloom in fresh and estuary water bodies.

  8. Leading edge vortex control on a delta wing with dielectric barrier discharge plasma actuators

    NASA Astrophysics Data System (ADS)

    Shen, Lu; Wen, Chih-yung

    2017-06-01

    This paper presents an experimental investigation of the application of dielectric barrier discharge (DBD) plasma actuators on a slender delta wing to control the leading edge vortices (LEVs). The experiments are conducted in a wind tunnel with a Reynolds number of 50 000 based on the chord length. The smoke flow visualization reveals that the DBD plasma actuators at the leading edges significantly modify the vortical flow structure over the delta wing. It is noted that symmetric control at both semi-spans and asymmetric control at a single semi-span leads to opposite effects on the local LEVs. Particle image velocimetry (PIV) indicates that the shear layer is deformed by the actuators. Therefore, both the strength and the shape of the LEV cores are deeply affected. The six-component force measurement shows that the DBD plasma actuators have a limited effect on lift and drag while inducing relatively large moments. This suggests that the DBD plasma actuator is a promising technique for delta wing maneuvering.

  9. Recent developments in DBD plasma flow control

    NASA Astrophysics Data System (ADS)

    Wang, Jin-Jun; Choi, Kwing-So; Feng, Li-Hao; Jukes, Timothy N.; Whalley, Richard D.

    2013-10-01

    Flow control using DBD (dielectric-barrier-discharge) plasma actuators is a relatively new, but rapidly expanding area of research. There are a number of review papers available on this subject, but few discuss on their latest developments. The purpose of the present article is to “fill the gap” by reviewing the recent trend of plasma actuator design and to summarise aerodynamic control techniques. Here, we review new plasma actuators, such as plasma synthetic jet actuators, plasma spark jet actuators, three-dimensional plasma actuators and plasma vortex generators, which can induce three-dimensional flows away from the wall. We also review the starting vortex that leads to formation of a plasma wall jet. This is an important subject not only for a better understanding of the flow induced by DBD plasma actuators, but also as a database that can be used to calibrate the numerical models for plasma flow control. Design of DBD plasma actuators to obtain turbulent skin-friction reduction is shown and the modifications to near-wall turbulence structures are summarised. Novel applications of DBD plasma actuators for aerodynamic control are then discussed, including pitch and roll control, plasma jet vectoring, circulation control and plasma flap, showing a potential of DBD plasma actuators for replacing movable, aircraft control surfaces. Finally, vortex shedding control techniques by a number of different plasma actuators are surveyed.

  10. Temporally, spatially, and spectrally resolved barrier discharge produced in trapped helium gas at atmospheric pressure

    SciTech Connect

    Chiper, Alina Silvia; Popa, Gheorghe

    2013-06-07

    Experimental study was made on induced effects by trapped helium gas in the pulsed positive dielectric barrier discharge (DBD) operating in symmetrical electrode configuration at atmospheric pressure. Using fast photography technique and electrical measurements, the differences in the discharge regimes between the stationary and the flowing helium are investigated. It was shown experimentally that the trapped gas atmosphere (TGA) has notable impact on the barrier discharge regime compared with the influence of the flowing gas atmosphere. According to our experimental results, the DBD discharge produced in trapped helium gas can be categorized as a multi-glow (pseudo-glow) discharge, each discharge working in the sub-normal glow regime. This conclusion is made by considering the duration of current pulse (few {mu}s), their maximum values (tens of mA), the presence of negative slope on the voltage-current characteristic, and the spatio-temporal evolution of the most representative excited species in the discharge gap. The paper focuses on the space-time distribution of the active species with a view to better understand the pseudo-glow discharge mechanism. The physical basis for these effects was suggested. A transition to filamentary discharge is suppressed in TGA mode due to the formation of supplementary source of seed electrons by surface processes (by desorption of electrons due to vibrationally excited nitrogen molecules, originated from barriers surfaces) rather than volume processes (by enhanced Penning ionisation). Finally, we show that the pseudo-glow discharge can be generated by working gas trapping only; maintaining unchanged all the electrical and constructive parameters.

  11. Research on the degradation mechanism of pyridine in drinking water by dielectric barrier discharge.

    PubMed

    Li, Yang; Yi, Rongjie; Yi, Chengwu; Zhou, Biyun; Wang, Huijuan

    2017-03-01

    Pyridine, an important chemical raw material, is widely used in industry, for example in textiles, leather, printing, dyeing, etc. In this research, a dielectric barrier discharge (DBD) system was developed to remove pyridine, as a representative type of nitrogen heterocyclic compound in drinking water. First, the influence of the active species inhibitors tertiary butanol alcohol (TBA), HCO3(-), and CO3(2-) on the degradation rate of pyridine was investigated to verify the existence of active species produced by the strong ionization discharge in the system. The intermediate and final products generated in the degradation process of pyridine were confirmed and analyzed through a series of analytical techniques, including liquid chromatography-mass spectrometry (LC-MS), high performance liquid chromatography (HPLC), ion chromatography (IC), total organic carbon (TOC) analysis, ultraviolet (UV) spectroscopy, etc. The results showed that the degradation of pyridine was mainly due to the strong oxidizing power of ozone and hydroxyl radical produced by the DBD system. Several intermediate products including 3-hydroxyl pyridine, fumaric acid, 2, 3-dihydroxypyridine, and oxalic acid were detected. Nitrogen was removed from the pyridine molecule to form nitrate. Through analysis of the degradation mechanism of pyridine, the oxidation pathway was deduced. The study provided a theoretical and experimental basis for the application of DBD strong ionization discharge in treatment of nitrogen heterocyclic compounds in drinking water. Copyright © 2016. Published by Elsevier B.V.

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

    NASA Astrophysics Data System (ADS)

    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.

  13. Acetamiprid removal in wastewater by the low-temperature plasma using dielectric barrier discharge.

    PubMed

    Li, Shanping; Ma, Xiaolong; Jiang, Yanyan; Cao, Xiaohong

    2014-08-01

    Degradation of acetamiprid in wastewater was studied in a dielectric barrier discharge (DBD) reactor. This reactor produces ultraviolet light and reactive species like ozone (O₃) can be used for the treatment of wastewater. We examined the factors that could affect the degradation process, including the discharge power, and the initial concentrations of acetamiprid, and O₃ which is generated by the DBD reactor. We also investigated the effect of adding Na₂B₄O₇ as a radical scavenger to probe the role of hydroxyl radical in the reaction. The results indicated that acetamiprid could be removed from aqueous solution effectively and hydroxyl radicals played an important role during the degradation by the low temperature plasma. The degradation process of acetamiprid fits the first-order kinetics. The degradation efficiency was 83.48 percent at 200 min when the discharge power was 170 W and the initial acetamiprid concentration was 50 mg/L. The removal efficiency of acetamiprid decreased with the increasing concentration of Na₂B₄O₇ because B₄O₇(2-) is an excellent radical scavenger that inhibited the generation of OH during the DBD process. The removal efficiency of acetamiprid improved in the presence of O₃. The main reason was that O₃ can oxidize certain organic compounds directly or indirectly by generating hydroxyl radicals. The degradation products of acetamiprid were characterized qualitatively and quantitatively using high performance liquid chromatography, mass spectrometry and UV-vis spectroscopy.

  14. Study of a Filamentary Dielectric Barrier Discharge in Air at Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Celestin, Sebastien; Zeghondy, Barbar; Guaitella, Olivier; Bourdon, Anne; Rousseau, Antoine

    2006-10-01

    Dielectric Barrier Discharges (DBD) at atmospheric pressure have many applications, for instance ozone production, surface treatment, and waste gas treatment. Generally, such a discharge is filamentary but it can be diffuse under particular conditions. Understanding the formation of the filament, which is an ionization wave or so-called ``streamer'', is very hard theoretically, numerically, and experimentally. This is due, first, to the non-linearity of the equations concerned, and second, because of the scaling in space and time of this phenomenon: a streamer has a radius on the order of a few microns, and propagates through distances of several centimeters in a few nanoseconds. In this study we will present the results obtained in experiments and in simulations for a plane-to-plane DBD. We electrically characterized this device and have observed collective effects that are still poorly understood. A point-to-plane DBD has also been studied for producing a much more localized discharge. In parallel with the experimental study we have developed a numerical model based on the Immersed Boundary Method (IBM) to introduce an electrode having a complex geometry into a structured Cartesian mesh. The first results of the code will be discussed.

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

    SciTech Connect

    Graz, I.; Schwoediauer, R.; Bauer, S.; Gruber, H.; Romanin, C.

    2005-10-17

    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.

  16. Thin film deposition at atmospheric pressure using dielectric barrier discharges: Advances on three-dimensional porous substrates and functional coatings

    NASA Astrophysics Data System (ADS)

    Fanelli, Fiorenza; Bosso, Piera; Mastrangelo, Anna Maria; Fracassi, Francesco

    2016-07-01

    Surface processing of materials by atmospheric pressure dielectric barrier discharges (DBDs) has experienced significant growth in recent years. Considerable research efforts have been directed for instance to develop a large variety of processes which exploit different DBD electrode geometries for the direct and remote deposition of thin films from precursors in gas, vapor and aerosol form. This article briefly reviews our recent progress in thin film deposition by DBDs with particular focus on process optimization. The following examples are provided: (i) the plasma-enhanced chemical vapor deposition of thin films on an open-cell foam accomplished by igniting the DBD throughout the entire three-dimensional (3D) porous structure of the substrate, (ii) the preparation of hybrid organic/inorganic nanocomposite coatings using an aerosol-assisted process, (iii) the DBD jet deposition of coatings containing carboxylic acid groups and the improvement of their chemical and morphological stability upon immersion in water.

  17. Treatment of poly(ethylene terephthalate) foils by atmospheric pressure air dielectric barrier discharge and its influence on cell growth

    NASA Astrophysics Data System (ADS)

    Kuzminova, Anna; Vandrovcová, Marta; Shelemin, Artem; Kylián, Ondřej; Choukourov, Andrei; Hanuš, Jan; Bačáková, Lucie; Slavínská, Danka; Biederman, Hynek

    2015-12-01

    In this contribution an effect of dielectric barrier discharge (DBD) sustained in air at atmospheric pressure on surface properties of poly(ethylene terephthalate) (PET) foils is studied. It is found that exposure of PET to DBD plasma leads to rapid changes of surface chemical composition, wettability, surface morphology as well as mechanical properties of PET surface. In addition, based on biological tests that were performed using two cell types (Saos-2 human osteoblast-like cells and HUVEC human umbilical vein endothelial cells), it may be concluded that DBD plasma treatment positively influences cell growth on PET. This effect was found to be connected predominantly with increased surface energy and oxygen content of the surface of treated PET foils.

  18. Functional relationship between material property, applied frequency and ozone generation for surface dielectric barrier discharges in atmospheric air.

    PubMed

    Portugal, Sherlie; Roy, Subrata; Lin, Jenshan

    2017-07-25

    We report the experimental characterization of ozone generation in dielectric barrier discharges as a function of the material and characteristics of the dielectric barrier, operating frequency and the power consumed by a surface DBD-plasma reactor in air at atmospheric pressure. To identify the effect of the dielectric barrier, ozone production curves corresponding to ten dielectric barriers with different effective thicknesses and thermal properties are compared and analyzed for two combinations of voltage amplitudes and frequencies: 7 kV/10 kHz and 8.5 kV/14 kHz. The influence of the operating frequency over the ozone generated by a DBD-plasma reactor is studied by varying the frequency in the range 8-20 kHz. The correlation between power measurements and ozone concentrations as well as ozone quenching effects at extreme power conditions are also discussed.

  19. The various dielectric barrier discharges lamps and plasma panel prototype designs developed in VNIIEF

    NASA Astrophysics Data System (ADS)

    Tsvetkov, V. M.; Pikulev, A. A.

    2008-01-01

    The various dielectric barrier discharges (DBD) lamps and plasma panel prototype designs developed in VNIIEF are presented. The lamps given, depending on a configuration of electrodes, it is possible to divide into three types: 1) a lamp with a plane-parallel configuration of the electrodes, intended for researching of barrier discharges parameters and UV-radiation of various mixes. The design of this lamp allows changing electrodes and varying distance between them; 2) lamps of cylindrical geometry. The external electrode is a spiral or a grid, and internal electrode is a metallic foil. Such design of lamps is the most widespread; 3) lamps with a planar configuration of electrodes. There are two types of lamps with a planar configuration of electrodes: 1) plasma panel prototypes and 2) lamps with ceramic barriers. Plasma panel prototypes are increased (in 50-100 times) copies of plasma display panels (PDP) and are intended for researching of the processes taking place in PDP. Using ceramic barriers of high capacity in DBD lamps allows receiving bigger power density of UV-radiation, than in case of glass (quartz) barriers.

  20. Black pepper powder microbiological quality improvement using DBD systems in atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Grabowski, Maciej; Hołub, Marcin; Balcerak, Michał; Kalisiak, Stanisław; Dąbrowski, Waldemar

    2015-07-01

    Preliminary results are given regarding black pepper powder decontamination using dielectric barrier discharge (DBD) plasma in atmospheric pressure. Three different DBD reactor constructions were investigated, both packaged and unpackaged material was treated. Due to potential, industrial applications, in addition to microbiological results, water activity, loss of mass and the properties of packaging material, regarding barrier properties were investigated. Argon based treatment of packed pepper with DBD reactor configuration is proposed and satisfactory results are presented for treatment time of 5 min or less. 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. [Measurement of molecular vibrational temperature in dielectric barrier discharge in argon/air at atmospheric pressure].

    PubMed

    Dong, Li-Fang; Liu, Feng; Li, Shu-Feng; Ran, Jun-Xia; He, Ya-Feng; Li, Xue-Chen; Pang, Xue-Xia

    2006-05-01

    Vibrational temperature of N2 (C 3IIu) molecules in dielectric barrier discharge (DBD) in argon/air at atmospheric pressure, in which the water electrodes were employed, was measured by using a method of spectrum diagnosis. Emission spectral lines of the N2 second positive band system(C 3IIu --> B 3IIg) and the sequences of vibrational bands with deltav = -1, deltav = -2 and deltav = -3 were used in the calculation. The experiment results show that the molecular vibrational temperature of N2 is in the range from 1 938 K to 2 720 K, and it increases almost linearly with increasing the air content in gas mixture. These results are of great importance to the study of plasma dynamics of DBD.

  2. Simultaneous removals of NOx, HC and PM from diesel exhaust emissions by dielectric barrier discharges.

    PubMed

    Song, Chong-Lin; Bin, Feng; Tao, Ze-Min; Li, Fang-Cheng; Huang, Qi-Fei

    2009-07-15

    The main target of this work is to characterize the abatements of particulate matter (PM), hydrocarbons (HC) and nitrogen oxides (NO(x)) from an actual diesel exhaust using dielectric barrier discharge technology (DBD). The effects of several parameters, such as peak voltage, frequency and engine load, on the contaminant removals have been investigated intensively. The present study shows that for a given frequency, the removals of PM and HC are enhanced with the increase of peak voltage and level off at higher voltage, while in the range of higher voltages a decline of NO(x) removal efficiency is observed. For a given voltage, the maximums of specific energy density (SED) and removal efficiency are attained at resonance point. The increase of peak voltage will result in a significant decrease of energy utilization efficiency of DBD at most engine loads. Alkanes in soluble organic fraction (SOF) are more readily subjected to removals than polycyclic aromatic hydrocarbons (PAHs).

  3. A novel two-level dielectric barrier discharge reactor for methyl orange degradation.

    PubMed

    Tao, Xumei; Wang, Guowei; Huang, Liang; Ye, Qingguo; Xu, Dongyan

    2016-12-15

    A novel pilot two-level dielectric barrier discharge (DBD) reactor has been proposed and applied for degradation of continuous model wastewater. The two-level DBD reactor was skillfully realized with high space utilization efficiency and large contact area between plasma and wastewater. Various conditions such as applied voltage, initial concentration and initial pH value on methyl orange (MO) model wastewater degradation were investigated. The results showed that the appropriate applied voltage was 13.4 kV; low initial concentration and low initial pH value were conducive for MO degradation. The percentage removal of 4 L MO with concentration of 80 mg/L reached 94.1% after plasma treatment for 80min. Based on ultraviolet spectrum (UV), Infrared spectrum (IR), liquid chromatography-mass spectrometry (LC-MS) analysis of degradation intermediates and products, insights in the degradation pathway of MO were proposed.

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

    NASA Astrophysics Data System (ADS)

    Tang, Shoufeng; Lu, Na; Shang, Kefeng; Li, Jie; Wu, Yan

    2013-03-01

    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.

  5. Time resolved Schlieren imaging of DBD actuator flow fields

    NASA Astrophysics Data System (ADS)

    Nourgostar, Cyrus; Oksuz, Lutfi; Hershkowitz, Noah

    2009-10-01

    Schlieren imaging methods measure the first derivative of density in the direction of a knife-edge spatial filter. It has been used extensively in aerodynamic research to visualize the structure of flow fields. With a single barrier planer dielectric barrier discharge (DBD) actuator, Schlieren images clearly show the absence of significant vertical air flow normal to the surface, and no more than few millimeters thick induced boundary layer flow. A gated intensified CCD camera along with a Schlieren system can not only visualize the flow field induced by the actuator, but also temporarily resolve the images of the flow and plasma field. Our time resolved images with triangular applied voltage waveforms indicate that several separate discharge regimes occur during positive and negative going half cycles of single and double barrier DBD actuators. Time resolved Schlieren imaging of both single and double barrier DBDs with different applied waveforms, discharge parameters and electrode geometries reveal important information on the induced flow structure.

  6. Simulation of pulsed dielectric barrier discharge xenon excimer lamp

    NASA Astrophysics Data System (ADS)

    Bogdanov, E. A.; Kudryavtsev, A. A.; Arslanbekov, R. R.; Kolobov, V. I.

    2004-11-01

    Recently, it has been shown that the efficiency of excimer lamps can be drastically increased in a pulsed regime. A one-dimensional simulation of pulsed excimer lamps has been performed by Carman and Mildren (2003 J. Phys. D: Appl. Phys. 36 19) (C&M). However, some computational results of the work of C&M are questionable and need to be revisited. In this paper, a dielectric barrier discharge (DBD) in xenon has been simulated for operating conditions similar to those of C&M to better understand plasma dynamics in a pulsed regime. Our simulation results differ considerably from the computational results of C&M. Although these differences do not affect profoundly the plasma macro parameters measured in the C&M experiments, they offer a better understanding of plasma dynamics in pulsed DBDs and form a solid foundation for computational optimization of excimer lamps. It was found that the dynamics of breakdown and the current pulse depend significantly on the initial densities of species after a previous pulse, and so it is important to accurately simulate the plasma evolution in both the afterglow and active stages. It seems possible to modify the power deposition in the plasma by varying external discharge parameters such as the amplitude and the rise time of the applied voltage, and to modify the plasma composition by changing the pulse repetition rate and plasma decay in the afterglow stage.

  7. Dielectric barrier discharges with steep voltage rise: mapping of atomic nitrogen in single filaments measured by laser-induced fluorescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Lukas, C.; Spaan, M.; Schulz-von der Gathen, V.; Thomson, M.; Wegst, R.; Döbele, H. F.; Neiger, M.

    2001-08-01

    Space and time resolved relative atomic density distributions of nitrogen have been measured for the first time at a single filament within a dielectric barrier discharge (DBD) reactor with submillimetre radial dimensions. Two-photon-Absorption Laser-Induced Fluorescence (TALIF) spectroscopy of atomic nitrogen using radiation at λ = 206.7 nm is applied to a DBD with fast rising voltage amplitudes. The decay time of the atomic nitrogen density depends strongly on the position within the discharge and the distance from the dielectric where the lifetime is maximum. Admixed oxygen leads to an increase of the N density decay by an order of magnitude even at small fractions.

  8. Experimental method to quantify the efficiency of the first two operational stages of nanosecond dielectric barrier discharge plasma actuators

    NASA Astrophysics Data System (ADS)

    Correale, G.; Avallone, F.; Starikovskiy, A. Yu

    2016-12-01

    A method to quantify the efficiency of the first two operational stages of a nanosecond dielectric barrier discharge (ns-DBD) plasma actuator is proposed. The method is based on the independent measurements of the energy of electrical pulses and the useful part of the energy which heats up the gas in the discharge region. Energy input is calculated via a back current shunt technique as the difference between the energy given and the energy reflected back. The ratio of the difference of the latter two quantities and the energy input gives the electrical efficiency (η E) of a ns-DBD. The extent of the energy deposited is estimated via Schlieren visualizations and infrared thermography measurements. Then, the ideal power flux obtained if all the inputted energy was converted into heat is calculated. Transient surface temperature was measured via infrared thermography and used to solve a 1D inverse heat transfer problem in a direction normal to the surface. It gives as output the actual power flux. The estimated ratio between the two power fluxes represents a quantification of the mechanical fluid efficiency (η FM) of a ns-DBD plasma actuator. Results show an inverse proportionality between η E, and η FM, and the thickness of the barrier. The efficiency of the first two operational stages of a ns-DBD is further defined as η  =  η E · η FM.

  9. Barriers to flashover discharge arcs on Teflon

    NASA Technical Reports Server (NTRS)

    Gossland, M.; Balmain, K. G.

    1982-01-01

    The effect of various barriers (empty gap, copper, Mylar, and nickel mesh) on the probability of simultaneous arc discharging of two physically separated pieces of electron-beam-charged Teflon was studied. For the empty gap barrier, it was found that simultaneous discharges rarely occur when the separation between the samples is greater than approximately 0.4 times the length of their common edge when this length is of the order of 1 cm. Evidence suggests that electromagnetic fields play a larger role than electrons in influencing the occurrence of simultaneous arc discharges.

  10. Ambient-temperature trap/release of arsenic by dielectric barrier discharge and its application to ultratrace arsenic determination in surface water followed by atomic fluorescence spectrometry

    USDA-ARS?s Scientific Manuscript database

    A novel dielectric barrier discharge reactor (DBDR) was utilized to trap/release arsenic coupled to hydride generation atomic fluorescence spectrometry (HGAFS). On the DBD principle, the precise and accurate control of trap/release procedures was fulfilled at ambient temperature, and an analytical m...

  11. Ozone production using dielectric barrier discharge in oxygen and carbon dioxide

    NASA Astrophysics Data System (ADS)

    Pontiga, Francisco; Abidat, Roukia; Moreno, Helena; Agustín, Fernández-Rueda; Rebiaï, Saida

    2015-09-01

    The generation of ozone in oxygen and carbon dioxide using a planar dielectric barrier discharge (DBD) has been experimentally investigated. The DBD reactor was operated at moderate voltages (4.2 to 5.6 kV) and frequencies (50 to 500 Hz) and the gas flow rate was varied in the range 50 to 200 cm3/min. The averaged consumed power (<1 W) was evaluated using a monitor capacitor of known capacitance (1 μF). The effluent gas from the DBD reactor was diverted to a gas cell situated inside the sample compartment of a UV spectrophotometer. Therefore, ozone concentration was determined from the measurement of absorbance using Beer-Lambert law. The results have shown that ozone concentration in oxygen grows very linearly with the input power. In contrast, the production of ozone in carbon dioxide is less regular, which may be due to the deposition of a thin layer over the stainless steel electrode during the application of the electrical discharge. Moreover, the rate of ozone production with the injected energy density was found to be 500 times weaker in carbon dioxide than in pure oxygen. This work was supported by the Spanish Government Agency ``Ministerio de Ciencia e Innovación'' under Contract No. FIS2011-25161.

  12. Reaction of Small Insects to an Ambient Pressure Dielectric Barrier Discharge

    NASA Astrophysics Data System (ADS)

    Bures, Brian; Gray, Travis; Bourham, Mohamed; Roe, R. Michael; Long, Shengyou; Donohue, Kevin

    2003-10-01

    Ambient Pressure Dielectric Barrier Discharges (DBD's) are commonly studied for rapid sterilization of surfaces. In an effort to expand the application of DBD's to larger biological species, small insect species are directly exposed to a large gap(5 cm) DBD composed primarily of helium gas. In order to control the temperature, the electrodes are actively cooled and the current density remains low (<1 mA/cm^2). A direct measurement of the gas temperature by electrically insulated thermocouples shows that the ambient temperature in the discharge volume is below the threshold for thermal damage to the insect (40 ^oC). A microwave interferometer is used to measure the line average, time average, electron density. The electron density is between 10^8 and 10^10 cm-3 for the operating conditions of interest. Under these operating conditions, optical emission spectroscopy shows only a significant emission of helium lines with some emission of molecular nitrogen lines. Under these operational conditions green peach aphids and western flower thrips show a reduction in population by at least 50% with a 60 s exposure time. The goal of this research is to replace currently existing chemical and thermal insect control techniques with the more rapid plasma techniques for quarantine applications.

  13. Discoloration of Congo Red by Rod-Plate Dielectric Barrier Discharge Processes at Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    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)

  14. Novel design of high voltage pulse source for efficient dielectric barrier discharge generation by using silicon diodes for alternating current

    NASA Astrophysics Data System (ADS)

    Truong, Hoa Thi; Hayashi, Misaki; Uesugi, Yoshihiko; Tanaka, Yasunori; Ishijima, Tatsuo

    2017-06-01

    This work focuses on design, construction, and optimization of configuration of a novel high voltage pulse power source for large-scale dielectric barrier discharge (DBD) generation. The pulses were generated by using the high-speed switching characteristic of an inexpensive device called silicon diodes for alternating current and the self-terminated characteristic of DBD. The operation started to be powered by a primary DC low voltage power supply flexibly equipped with a commercial DC power supply, or a battery, or DC output of an independent photovoltaic system without transformer employment. This flexible connection to different types of primary power supply could provide a promising solution for the application of DBD, especially in the area without power grid connection. The simple modular structure, non-control requirement, transformer elimination, and a minimum number of levels in voltage conversion could lead to a reduction in size, weight, simple maintenance, low cost of installation, and high scalability of a DBD generator. The performance of this pulse source has been validated by a load of resistor. A good agreement between theoretically estimated and experimentally measured responses has been achieved. The pulse source has also been successfully applied for an efficient DBD plasma generation.

  15. Statistical Analysis of Reducing Biochemical Oxygen Demand (BOD) on Industrial Rubber Wastewater using Dielectric Barrier Discharge Plasma

    NASA Astrophysics Data System (ADS)

    Syakur, Abdul; Zaman, Badrus; Yunita Nurmaliakasih, Dias

    2017-04-01

    Dielectric Barrier Discharge plasma (DBD) is one of type non-thermal plasma (non-equilibrium plasma) or can be referred to as cold plasma. In this research, DBD plasma be utilized to reduce organic compounds like Biochemichal oxygen demand in the wastewater rubber processing. In the environment field DBD plasma has been used as a treatment for reducing air pollutants such as gas COx, NOx and HC. In addition DBD plasma have been developed to processed wastewater as an alternative technology in wastewater treatment. DBD plasma appears when the electrode is given a high voltage so that, it will form electric field in the area of the electrodes which allows the ionization and the presence of high-energy electrons in the area. The presence of these electrons will ionize molecules of H2O into active species such as OH•, H• and H2O2. The active species that can oxidize into CO2 and H2O so, BOD that can be degraded. In this research for wastewater treatment used high voltage are 10kV, 11kV, 12kV and 13kV and variations of processing time for 5, 10, 15, 20, and 25 (minutes). By increasing the voltage and extend the contact time then the speed variation of electrons to ionize the greater and more active species to be formed to degrade the pollutants to the maximum. This research used quantitative analysis with statistical analysis using SPSS software.

  16. Metal carbonyl vapor generation coupled with dielectric barrier discharge to avoid plasma quench for optical emission spectrometry.

    PubMed

    Cai, Yi; Li, Shao-Hua; Dou, Shuai; Yu, Yong-Liang; Wang, Jian-Hua

    2015-01-20

    The scope of dielectric barrier discharge (DBD) microplasma as a radiation source for optical emission spectrometry (OES) is extended by nickel carbonyl vapor generation. We proved that metal carbonyl completely avoids the extinguishing of plasma, and it is much more suitable for matching the DBD excitation and OES detection with respect to significant DBD quenching by concomitant hydrogen when hydride generation is used. A concentric quartz UV reactor allows sample solution to flow through the central channel wherein to efficiently receive the uniformly distributed UV irradiation in the confined cylindrical space between the concentric tubes, which facilitates effective carbonyl generation in a nickel solution. The carbonyl is transferred into the DBD excitation chamber by an argon stream for nickel excitation, and the characteristic emission of nickel at 232.0 nm is detected by a charge-coupled device (CCD) spectrometer. A 1.0 mL sample solution results in a linear range of 5-100 μg L(-1) along with a detection limit of 1.3 μg L(-1) and a precision of 2.4% RSD at 50 μg L(-1). The present DBD-OES system is validated by nickel in certified reference materials.

  17. Morphological and chemical changes of aerosolized E. coli treated with a dielectric barrier discharge

    SciTech Connect

    Romero-Mangado, Jaione; Nordlund, Dennis; Soberon, Felipe; Deane, Graham; Maughan, Kevin; Sainio, Sami; Singh, Gurusharan; Daniels, Stephen; Saunders, Ian T.; Loftus, David; Meyyappan, M.; Koehne, Jessica; Gandhiraman, Ram P.

    2016-02-12

    This paper presents the morphological and chemical modification of the cell structure of aerosolized Escherichia coli treated with a dielectric barrier discharge (DBD). Exposure to DBD results in severe oxidation of the bacteria, leading to the formation of hydroxyl groups and carbonyl groups and a significant reduction in amine functionalities and phosphate groups. Near edge x-ray absorption fine structure(NEXAFS) measurements confirm the presence of additional oxide bonds upon DBD treatment, suggesting oxidation of the outer layer of the cell wall. Electron microscopy images show that the bacteria undergo physical distortion to varying degrees, resulting in deformation of the bacterial structure. The electromagnetic field around the DBD coil causes severe damage to the cell structure, possibly resulting in leakage of vital cellular materials. The oxidation and chemical modification of the bacterial components are evident from the Fourier transform infrared spectroscopy and NEXAFS results. The bacterial reculture experiments confirm inactivation of airborne E. coli upon treating with DBD.

  18. Experimental Determination of Spatial and Temporal Discharge Parameters for an Ambient Pressure Dielectric Barrier Discharge in Helium

    NASA Astrophysics Data System (ADS)

    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. Dielectric barrier discharge control of a turbulent boundary layer in a supersonic flow

    SciTech Connect

    Im, S.; Do, H.; Cappelli, M. A.

    2010-07-26

    We demonstrate effective manipulation of a turbulent boundary layer at Mach 4.7 conditions using a surface dielectric barrier discharge (DBD) actuator. The freestream conditions of low static pressure (1 kPa) and temperature (60 K) are conducive to the visualization of flow features using Rayleigh scattering from condensed CO{sub 2} particles. The boundary layer thinning is observed when spanwise momentum is induced by the low power (6.8 W), low frequency (28 kHz) single actuator pair oriented parallel to the freestream flow.

  20. Impact of gas flow rate on breakdown of filamentary dielectric barrier discharges

    NASA Astrophysics Data System (ADS)

    Höft, H.; Becker, M. M.; Kettlitz, M.

    2016-03-01

    The influence of gas flow rate on breakdown properties and stability of pulsed dielectric barrier discharges (DBDs) in a single filament arrangement using a gas mixture of 0.1 vol. % O2 in N2 at atmospheric pressure was investigated by means of electrical and optical diagnostics, accompanied by fluid dynamics and electrostatics simulations. A higher flow rate perpendicular to the electrode symmetry axis resulted in an increased breakdown voltage and DBD current maximum, a higher discharge inception jitter, and a larger emission diameter of the discharge channel. In addition, a shift of the filament position for low gas flow rates with respect to the electrode symmetry axis was observed. These effects can be explained by the change of the residence time of charge carriers in the discharge region—i.e., the volume pre-ionization—for changed flow conditions due to the convective transport of particles out of the center of the gap.

  1. Impact of gas flow rate on breakdown of filamentary dielectric barrier discharges

    SciTech Connect

    Höft, H. Becker, M. M.; Kettlitz, M.

    2016-03-15

    The influence of gas flow rate on breakdown properties and stability of pulsed dielectric barrier discharges (DBDs) in a single filament arrangement using a gas mixture of 0.1 vol. % O{sub 2} in N{sub 2} at atmospheric pressure was investigated by means of electrical and optical diagnostics, accompanied by fluid dynamics and electrostatics simulations. A higher flow rate perpendicular to the electrode symmetry axis resulted in an increased breakdown voltage and DBD current maximum, a higher discharge inception jitter, and a larger emission diameter of the discharge channel. In addition, a shift of the filament position for low gas flow rates with respect to the electrode symmetry axis was observed. These effects can be explained by the change of the residence time of charge carriers in the discharge region—i.e., the volume pre-ionization—for changed flow conditions due to the convective transport of particles out of the center of the gap.

  2. VUV Emissions from a High-Pressure Cylindrical Dielectric Barrier Discharge

    NASA Astrophysics Data System (ADS)

    Martus, Kevin; Masoud, Nazieh; Becker, Kurt; Laroussi, Mounir

    2003-05-01

    High-pressure Dielectric Barrier Discharges (DBDs) produce non-equilibrium plasmas that can be used in a variety of applications. The emissions from a high-pressure cylindrical DBD in a mixture of Ne and H2 (less than 0.5proposed as a light source for 121.6nm radiation. Neon resonance lines and excimer emissions as well as, Hydrogen Lyman-alpha emission lines have been analyzed from a cylindrical DBD plasma in this work. The discharge source consists of a 1/4" dielectric tube with two outer electrodes and the discharge is sustained by RF power at 13.56MHz. The discharge is contained inside the tube with pressures ranging from 1 to 760 Torr and a gas flow rate that is adjustable from 25 to 600 sccm. The emissions were analyzed using a Minuteman 302-V 0.2m VUV spectrometer with an CCD camera to detect the photons in the wavelength range from 50 150nm. Results of measurements of the relative intensity of the resonance lines and excimer emission for pure Neon and Neon-Hydrogen admixtures as a function of Hydrogen concentration, discharge pressure, gas flow rate, and RF power will be presented and discussed. Work supported by NSF and the WPUNJ Sabbatical Leave Program.

  3. Discharge Modes Suggested by Emission Spectra of Nitrogen Dielectric Barrier Discharge with Wire-Cylinder Electrodes

    NASA Astrophysics Data System (ADS)

    Yang, Fuxiang; Mu, Zongxin; Zhang, Jialiang

    2016-01-01

    In this paper, nitrogen dielectric barrier discharge (DBD) plasma was generated in a quartz tube with coaxial wire-cylinder electrodes at atmospheric pressure. By varying the nitrogen gas flow (FN) in the range of 0-1 m3/h, the plasma optical emission spectra (OES) were measured and studied. The vibration (Tvib) and rotation temperature (Trot) of nitrogen were obtained, by fitting the rovibronic bands of N2(C3Πu - B3Πg, 0-1), and by the Boltzmann plot method for purposes of comparison. Tvib increased up to 2481 K with increasing nitrogen flow till 0.2 m3/h, and then decreased with further increasing FN, while Trot decreased monotonously and approached to ˜350 K for FN ≥ 0.6 m3/h. The intensity of N2(C3Πu - B3Πg, 0-0, 1-0, 0-3) and N2+ (B2Σu+ - X2 Σ+g, 0-0) exhibited similar evolution with increasing FN to those of the Tvib and Trot, respectively. The discharge photos revealed that the discharge filaments gradually decreased with increasing FN, and eventually disappeared, which implied that a discharge mode transition emerged with increasing FN. The possible mechanism for the discharge mode transition is studied in detail according to the vibration (Tvib) and rotation temperature (Trot) of nitrogen. supported by National Natural Science Foundation of China (Nos. 11475040, 11375041) and the Fundamental Research Funds for the Central Universities (No. DUT14ZD[G]04)

  4. Dielectric barrier discharge image processing by Photoshop

    NASA Astrophysics Data System (ADS)

    Dong, Lifang; Li, Xuechen; Yin, Zengqian; Zhang, Qingli

    2001-09-01

    In this paper, the filamentary pattern of dielectric barrier discharge has been processed by using Photoshop, the coordinates of each filament can also be obtained. By using Photoshop two different ways have been used to analyze the spatial order of the pattern formation in dielectric barrier discharge. The results show that the distance of the neighbor filaments at U equals 14 kV and d equals 0.9 mm is about 1.8 mm. In the scope of the experimental error, the results from the two different methods are similar.

  5. Rapid mortality of pest arthropods by direct exposure to a dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Bures, Brian Lee

    The spread of arthropods due to trade of agricultural commodities and travel of humans is a significant problem in many countries. Limiting the movement of pest species is commonly achieved by the use of chemical pesticides at quarantine facilities. One potential alternative to chemical pesticides is direct exposure of contaminated commodities to ambient pressure electrical discharges. The arthropods are directly exposed to a 5.0 cm helium discharge with power densities on the order of 60 mW/cm3. Direct measurement of chemical species and ambient gas temperature shows the DBD treatment remains effective when the chemically reactive species are suppressed by helium, and when the ambient gas temperature of the discharge is below 40°C. In addition to gas temperature measurements and chemical species identification, the electron temperature and electron density were measured using the neutral bremsstrahlung continuum technique. This study is the first successful implementation of the neutral bremsstrahlung continuum emission diagnostic to a barrier discharge. The primary advantages of the diagnostic for barrier discharges are the measurement is passive and the spatial resolution is only limited by the collimation of the light and the sensitivity of the detector. Although the electron temperature (1.0--1.5 eV) and electron density (˜108 cm-3) are modest, non-chemical dielectric barrier discharge (DBD) treatment of arthropods has proven effective in significantly reducing the population of some arthropods including human body lice, green peach aphids, and western flower thrips. However, the treatment was not universally effective on all arthropod species. German cockroaches and citrus mealy bugs showed substantial resistance to the treatment. The study has shown the treatment does not always induce instant mortality: however, the mortality increases over a 24 hr-period after treatment. Based upon visual observation and the time after treatment to reach maximum

  6. Numerical investigation of co-axial DBD: Influence of relative permittivity of the dielectric barrier, applied voltage amplitude, and frequency

    NASA Astrophysics Data System (ADS)

    Gadkari, Siddharth; Gu, Sai

    2017-05-01

    In this work, a one-dimensional numerical fluid model is developed for co-axial dielectric barrier discharge in pure helium and a parametric study is performed to systematically study the influence of relative permittivity of the dielectric barrier and the applied voltage amplitude and frequency on the discharge performance. Discharge current, gap voltage, and spatially averaged electron density profiles are presented as a function of relative permittivity and voltage parameters. For the geometry under consideration, both the applied voltage parameters are shown to increase the maximum amplitude of the discharge current peak up to a certain threshold value, above which it stabilized or decreased slowly. The spatially averaged electron density profiles follow a similar trend to the discharge current. Relative permittivity of the dielectric barrier is predicted to have a positive influence on the discharge current. At lower frequency, it is also shown to lead to a transition from Townsend to glow discharge mode. Spatially and time averaged power density is also calculated and is shown to increase with increasing relative permittivity, applied voltage amplitude, and frequency.

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

    PubMed

    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. Copyright (c) 2010 Elsevier B.V. All rights reserved.

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

    NASA Astrophysics Data System (ADS)

    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

  9. Optical and electrical characteristics of a single surface DBD micro-discharge produced in atmospheric-pressure nitrogen and synthetic air

    NASA Astrophysics Data System (ADS)

    Šimek, M.; Prukner, V.; Schmidt, J.

    2011-05-01

    Basic opto-electrical characteristics of a single micro-discharge generated in a surface DBD reactor with a coplanar electrode arrangement were studied with nanosecond time resolution. The discharge electrode geometry based on machinable glass-ceramic was optimized in order to get a system free of the circulating dielectric liquids that are frequently used to insulate and cool metallic electrodes. The build-up and decay of UV-vis-NIR emission by a single micro-discharge unaffected by concurrent or preceding discharge events was inspected during the first 10 µs of the micro-discharge evolution in nitrogen and in synthetic air. Obtained emission waveforms show a great similarity between the surface and volume streamers. The streamer volume-averaged N2(A) concentrations of ~8 × 1014 cm-3 were estimated at t = 1 µs decay time and concentrations of ~(2-4) × 1015 cm-3 were estimated during the streamer propagation phase in nitrogen.

  10. Pulsed-DC DBD Plasma Actuators

    NASA Astrophysics Data System (ADS)

    Duong, Alan; McGowan, Ryan; Disser, Katherine; Corke, Thomas; Matlis, Eric

    2016-11-01

    A new powering system for dielectric barrier discharge (DBD) plasma actuators that utilizes a pulsed-DC waveform is presented. The plasma actuator arrangement is identical to most typical AC-DBD designs with staggered electrodes that are separated by a dielectric insulator. However instead of an AC voltage input to drive the actuator, the pulsed-DC utilizes a DC voltage source. The DC source is supplied to both electrodes, and remains constant in time for the exposed electrode. The DC source for the covered electrode is periodically grounded for very short instants and then allowed to rise to the source DC level. This process results in a plasma actuator body force that is significantly larger than that with an AC-DBD at the same voltages. The important characteristics used in optimizing the pulsed-DC plasma actuators are presented. Time-resolved velocity measurements near the actuator are further used to understand the underlying physics of its operation compared to the AC-DBD. Supported by NASA Glenn RC.

  11. Simulation study of one-dimensional self-organized pattern in an atmospheric-pressure dielectric barrier discharge

    SciTech Connect

    Zhang, Jiao; Wang, Yanhui Wang, Dezhen

    2015-04-15

    A two-dimensional fluid model is developed to simulate the one-dimensional self-organized patterns in an atmospheric-pressure dielectric barrier discharge (DBD) driven by sinusoidal voltage in argon. Under certain conditions, by changing applied voltage amplitude, the transversely uniform discharge can evolve into the patterned discharge and the varied self-organized patterned discharges with different numbers and arrangements of discharge channels can be observed. Similar to the uniform atmospheric-pressure DBD, the patterned discharge mode is found to undergo a transition from Townsend regime, sub-glow regime to glow regime with increasing applied voltage amplitude. In the different regimes, charged particles and electric field display different dynamical behaviors. If the voltage amplitude is increased over a certain value, the discharge enters an asymmetric patterned discharge mode, and then transforms into the spatially chaotic state with out-of-order discharge channels. The reason for forming the one-dimensional self-organized pattern is mainly due to the so-called activation-inhibition effect resulting from the local high electron density region appearing in discharge space. Electrode arrangement is the reason that induces local high electron density.

  12. Effects of oxygen concentration on atmospheric pressure dielectric barrier discharge in Argon-Oxygen Mixture

    NASA Astrophysics Data System (ADS)

    Li, Xuechun; Li, Dian; Wang, Younian

    2016-09-01

    A dielectric barrier discharge (DBD) can generate a low-temperature plasma easily at atmospheric pressure and has been investigated for applications in trials in cancer therapy, sterilization, air pollution control, etc. It has been confirmed that reactive oxygen species (ROS) play a key role in the processes. In this work, we use a fluid model to simulate the plasma characteristics for DBD in argon-oxygen mixture. The effects of oxygen concentration on the plasma characteristics have been discussed. The evolution mechanism of ROS has been systematically analyzed. It was found that the ground state oxygen atoms and oxygen molecular ions are the dominated oxygen species under the considered oxygen concentrations. With the oxygen concentration increasing, the densities of electrons, argon atomic ions, resonance state argon atoms, metastable state argon atoms and excited state argon atoms all show a trend of decline. The oxygen molecular ions density is high and little influenced by the oxygen concentration. Ground state oxygen atoms density tends to increase before falling. The ozone density increases significantly. Increasing the oxygen concentration, the discharge mode begins to change gradually from the glow discharge mode to Townsend discharge mode. Project supported by the National Natural Science Foundation of China (Grant No. 11175034).

  13. Development of a dielectric barrier discharge enhanced plasma jet in atmospheric pressure air

    SciTech Connect

    Li Xuechen; Chang Yuanyuan; Jia Pengying; Xu Longfei; Fang Tongzhen; Wang Long

    2012-09-15

    A plasma jet equipped with dielectric barrier discharge (DBD) is developed to generate diffuse air plasma with fairly large gap and cross sectional area. The diffuse air plasma has two discharge modes under different gap widths from the nozzle to the ground plate electrode. For large gap width, a diffuse plume fills the whole space between the nozzle and the plate electrode after coaxial DBD is ignited when the applied voltage reaches a certain value. Rather than diffuse plasma plume, a bright plasma column bridges the nozzle and the plate electrode with further increasing the applied voltage under small gap width. By optical and electrical measurement, results show that the macroscopically diffuse discharge in air is obtained by the superimposition of radially distributed streamers that appear at different cycles of the applied voltage, and the bright plasma column belongs to atmospheric pressure glow discharge. The molecular vibrational temperature and the gas temperature are given as functions of the peak value of the applied voltage.

  14. Dielectric barrier discharge carbon atomic emission spectrometer: universal GC detector for volatile carbon-containing compounds.

    PubMed

    Han, Bingjun; Jiang, Xiaoming; Hou, Xiandeng; Zheng, Chengbin

    2014-01-07

    It was found that carbon atomic emission can be excited in low temperature dielectric barrier discharge (DBD), and an atmospheric pressure, low power consumption, and compact microplasma carbon atomic emission spectrometer (AES) was constructed and used as a universal and sensitive gas chromatographic (GC) detector for detection of volatile carbon-containing compounds. A concentric DBD device was housed in a heating box to increase the plasma operation temperature to 300 °C to intensify carbon atomic emission at 193.0 nm. Carbon-containing compounds directly injected or eluted from GC can be decomposed, atomized, and excited in this heated DBD for carbon atomic emission. The performance of this new optical detector was first evaluated by determination of a series of volatile carbon-containing compounds including formaldehyde, ethyl acetate, methanol, ethanol, 1-propanol, 1-butanol, and 1-pentanol, and absolute limits of detection (LODs) were found at a range of 0.12-0.28 ng under the optimized conditions. Preliminary experimental results showed that it provided slightly higher LODs than those obtained by GC with a flame ionization detector (FID). Furthermore, it is a new universal GC detector for volatile carbon-containing compounds that even includes those compounds which are difficult to detect by FID, such as HCHO, CO, and CO2. Meanwhile, hydrogen gas used in conventional techniques was eliminated; and molecular optical emission detection can also be performed with this GC detector for multichannel analysis to improve resolution of overlapped chromatographic peaks of complex mixtures.

  15. Transition Control with Dielectric Barrier Discharge Plasmas

    DTIC Science & Technology

    2013-01-01

    2] Bénard, N., Balcon , N. and Moreau, E. (2008): Electric wind produced by a surface dielec- tric barrier discharge operating in air at different...pressures: aeronautical control insights. J. Phys. D: Appl. Phys., 41(4):042002 (5pp). [3] Bénard, N., Balcon , N. and Moreau, E. (2009): Electric wind

  16. Performance of a large-scale barrier discharge plume improved by an upstream auxiliary barrier discharge

    NASA Astrophysics Data System (ADS)

    Li, Xuechen; Chu, Jingdi; Zhang, Qi; Zhang, Panpan; Jia, Pengying; Geng, Jinling

    2016-11-01

    Enhanced by an upstream auxiliary dielectric barrier discharge (ADBD), a transverse barrier discharge plume with a fairly large scale is generated downstream of a narrow slit. Electrical and optical characteristics are compared for the two discharges with and without the ADBD. Results indicate that the plume with the ADBD is longer, more uniform, and dissipates a higher power. Moreover, its inception voltage is much lower. High-speed imaging presents that the uniform plasma plume with the ADBD comprises a series of moving micro-discharge filaments in a glow regime, which are much smoother than those without the ADBD.

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

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

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

  18. Optical characteristics of the filamentary and diffuse modes in surface dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Zhang, Ying; Li, Jie; Jiang, Nan; Shang, Ke-Feng; Lu, Na; Wu, Yan

    2016-11-01

    Surface dielectric barrier discharge (DBD) plasmas generally exhibits filamentary and diffuse discharges at atmospheric air. The focus of this investigation is on the different optical characteristics and quantitative research about morphological features of two discharge modes. The temporally and spatially resolved characteristics of discharge phenomenon together with the gas temperature are presented with microsecond time scale. Discharge area is estimated by the sum of pixels that equal to "1" in MATLAB software. The formation of diffuse plasma mainly depends on an increase of the ionization coefficient and a creation of sufficient seed electrons by the Penning effect at low electric fields. Accordingly, experimental measurements show that diffuse discharge during the negative half cycle has good uniformity and stability compared with filamentary discharge during the positive half cycle. The rotational temperatures of plasma are determined by comparing the experimental spectra with the simulated spectra that have been investigated. The plasma gas temperature keeps almost constant in the filamentary discharge phase and subsequently increased by about 115 K during the diffuse discharge. In addition, it is shown to be nearly identical in the axial direction. Non-uniform temperature distribution can be observed in the radial direction with large fluctuations. The plasma length is demonstrated almost the same between two discharge modes.

  19. Cellular Structure Pattern in Dielectric Barrier Discharge

    NASA Astrophysics Data System (ADS)

    Zhang, Hao; Dong, Lifang; Liu, Weibo; Gao, Xing; Wei, Lingyan

    2015-12-01

    We report the observation of a cellular structure pattern in a dielectric barrier discharge system. The evolution sequence and phase diagram of the pattern are given. It is firstly observed that the "cell nucleus" fire three or even more times at a fixed location at the rising edge of the applied voltage, and that the "cell walls" which have the same discharge times with the "cell nucleus" are ignited slightly after the "cell nucleus". By observing a series of frames recorded by a high speed video camera, it is found that the cellular structure pattern consists of volume discharges (VDs) and surface discharges (SDs) corresponding to the "cell nucleus" and "cell walls" respectively. That VDs and SDs are ignited in turn for several times in each half cycle of the applied voltage confirms the fact that VDs induce the SDs and SDs also affect the following VDs.

  20. Nanosecond pulsed dielectric barrier discharge plasma-catalytic removal of HCHO in humid air

    NASA Astrophysics Data System (ADS)

    Zhang, Shuai; Wang, Wenchun; Zhang, Li; Zhao, Zilu; Yang, Dezheng

    2017-05-01

    Non-thermal plasma (NTP) has been regarded as a promising method for the removal of a wide range of low concentration volatile organic compounds (VOCs). In this paper, nanosecond pulsed and alternating current dielectric barrier discharge plasmas synergistic catalyst are utilized for removal of formaldehyde (HCHO) in humid air. Working gas is 1% H2O/21% O2/78% N2 with 154 ppm HCHO over total flow rate of 50 mL/min. Specific energy density (SED) are 32.5 JL-1, 35.8 JL-1 and 1069.2 JL-1 at power consumption of 0.325 W, 0.3 W, 8.9 W for removal of 67%, 63.8% and 73.8% HCHO when using bipolar nanosecond pulsed, unipolar nanosecond pulsed and AC dielectric barrier discharge (DBD) plasma, respectively. The removal efficiencies of HCHO using nanosecond pulsed DBD plasma increase approximately 10 20% when the packed-bed Al2O3 pellets exist and can reach up to almost 100% when TiO2 nanoparticles are used while the effect of CeO2 nanoparticles is a bit poor. Analysis indicate that OH radical and O atom play main role for removal HCHO and the gas temperature is a significant factor for its influence on rate constants of HCHO with active particles.

  1. Investigation of the electrode surface geometry effects driven by nanosecond-pulsed surface dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Xu, S. Y.; Cai, J. S.; Zhang, Z. K.; Tang, S. J.

    2017-05-01

    Nanosecond-pulsed surface dielectric barrier discharge (NS-DBD) plasma actuations with powered electrodes of different surface geometries were investigated numerically by solving the coupled plasma discharge equations, electron energy equations and the Navier-Stokes equations in quiescent air at atmospheric pressure. The plasma discharge characteristics and the air flow features were simulated numerically using a simple chemical kinetics plasma model for three powered electrodes with serrated, rectangular and semicircular surfaces, respectively. The results show that the reduced electric field of the serrated electrode is globally the strongest, while that of the rectangular electrode the second strongest, and that of the semicircular electrode the weakest. The maximum values of the reduced electric field, the mean electron energy and the electron density are found to occur immediately near the right upper tips of the powered electrodes, and the streamers of the mean electron energy and electron density in the serrated electrode case are larger in size and higher in value than in the rectangular and semicircular electrode cases. On the other hand, the pressure wave in the serrated electrode case is more intensive, and propagates slightly faster than in the other two electrode cases. Besides, the heated region in the serrated electrode case is greater with a higher temperature than in the other two electrode cases. The comparison results indicate that the performance of NS-DBD plasma actuators depends significantly on the powered electrode surface geometry, and the serrated surface design is a very promising means of flow control.

  2. Self-organized plasmas formed by accumulated charge in dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Akashi, Haruaki; Yoshinaga, Tomokazu

    2016-09-01

    Atmospheric pressure dielectric barrier discharges (DBDs) have been widely applied to various research fields, such as bio-medical treatment, toxic decomposition and so on. However, the details of DBD have not been understood yet. Because the phenomena occur in nanosecond time scale under atmospheric pressure. It is known that DBDs are significantly affected by accumulated charges on dielectrics, but the distributions and development of accumulated charges are not known for years. To clarify the distributions and the developments of accumulated charges on dielectrics and electron behavior in the vicinity of dielectrics, DBDs in atmospheric pressure oxygen have been simulated using a two dimensional fluid model with relatively high electron emission coefficient. In this condition, DBD simulation results are obtained in so called self-organized form. As a result, the locations of highly accumulated charges are at where the primary streamers reached in a half cycle. And the charges on the dielectrics become almost zero by the electrons after the change of discharge voltage polarity. The electron distribution in the vicinity of the dielectric forms similar to that of accumulated charges to compensate the charges. Excess electrons in front of dielectric become the seed electrons for next half cycle. This continuation makes discharge in self-organized form.

  3. Investigation of DBD for Fabrics Depending on Experimental Parameters

    NASA Astrophysics Data System (ADS)

    Korkmaz, Sunduz; Oksuz, Lutfi; Goktepe, Fatma; Helhel, Selcuk; Kati, Evren

    2004-09-01

    The presence of scale on a wool and cotton fiber surface introduces a number of problems such as felting and a surface barrier to dyestuffs in the wool and cotton industry. In the past, chemical methods were the major treatment for eliminating those problems. However, the effluents generated from wool and cotton dyeing and finishing processes are seriously contaminated with different kinds of chemicals, e.g. chlora-organic compounds from the anti-felt process. With the increasing of ecological and economical restrictions imposed on the textile industry, the industries were required to find environmentally favorable alternatives in wool and cotton treatment processes. Dielectric barrier discharge (DBD) is one of the treatment methods. The results of the surface treatment, using an atmospheric pressure dielectric barrier discharge (DBD), of wool and cotton in order to establish the most suitable conditions for textile treatments, are presented. Surface treatments will be performed with different applied voltages, different gap sizes, different thicknesses of dielectric at atmospheric pressure of air conditions. Scanning Electron Microscope (SEM) will be used to detect the physical surface changes on the samples. Surface luster, wet ability, dye ability of specimens will be presented. Breaking extension for cotton is increased by about 21% in length from 14.4mm to 17.47mm by DBD and about 27% in length from 14.4 to 18.254 by ECR. ECR modified samples are more strength than DBD applied. Hydrofility for cotton is also increased.

  4. Wind Tunnel Testing of a Hydrogen Jet in a Turbulent Crossflow Altered by a Dielectric Barrier Discharge

    NASA Astrophysics Data System (ADS)

    Fontaine, Ryan; Retter, Jonathan; Freund, Jonathan; Glumac, Nick; Elliott, Gregory

    2015-11-01

    It has been demonstrated that plasmas can fundamentally alter the combustion process. The radical production can decrease combustion timescales and the body force produced by the driving electric currents can improve fuel/oxidizer mixing and alter the shape of the steady state flame. We study these mechanisms for a fuel jet exhausting into a well-characterized turbulent cross-flow of air acted upon by a Dielectric Barrier Discharge (DBD) plasma produced at the jet exit. The fuel is hydrogen diluted in cases with N2 and Ar. Laser breakdown provides the energy deposition for ignition above the jet. The likelihood of sustained ignition for various fuel compositions and cross-flow conditions is considered along with flame properties once ignited both under the influence of the DBD plasma and without. Additionally, the effect of the DBD on flame blow-off is investigated. The jet is varied from low-momentum ratios (~ 10-4) to high (~ 1) to alter the relative contributions of the body forces and radical production on the combustion process. This system is studied to quantify the effect of the DBD plasma and discover opportunities for control. This material is supported by the DOE, NNSA, Award DE-NA0002374.

  5. Changes in the biomechanical properties of a single cell induced by nonthermal atmospheric pressure micro-dielectric barrier discharge plasma.

    PubMed

    Choi, Hyeongwon; Choi, Eun Ha; Kim, Kyung Sook

    2017-10-01

    Mechanical properties of a single cell are closely related to the fate and functions of the cell. Changes in mechanical properties may cause diseases or cell apoptosis. Selective cytotoxic effects of nonthermal atmospheric pressure micro-dielectric barrier discharge (DBD) plasma have been demonstrated on cancer cells. In this work, changes in the mechanical properties of a single cell induced by nonthermal atmospheric pressure micro-DBD plasma were investigated using atomic force microscopy (AFM). Two cervical cancer cell lines (HeLa and SiHa) and normal human fibroblast cells (HFBs) were exposed to micro-DBD plasma for various exposure times. The elasticity of a single cell was determined by force-distance curve measurement using AFM. Young's modulus was decreased by plasma treatment for all cells. The Young's modulus of plasma-treated HeLa cells was decreased by 75% compared to nontreated HeLa cells. In SiHa cells and HFBs, elasticity was decreased slightly. Chemical changes induced by the plasma treatment, which were observed by Raman spectroscopy, were also significant in HeLa cells compared to SiHa cells and HFBs. These results suggested that the molecular changes induced by micro-DBD plasma were related to cell mechanical changes. © 2017 Wiley Periodicals, Inc.

  6. A dielectric barrier discharge terminally inactivates RNase A by oxidizing sulfur-containing amino acids and breaking structural disulfide bonds

    NASA Astrophysics Data System (ADS)

    Lackmann, J.-W.; Baldus, S.; Steinborn, E.; Edengeiser, E.; Kogelheide, F.; Langklotz, S.; Schneider, S.; Leichert, L. I. O.; Benedikt, J.; Awakowicz, P.; Bandow, J. E.

    2015-12-01

    RNases are among the most stable proteins in nature. They even refold spontaneously after heat inactivation, regaining full activity. Due to their stability and universal presence, they often pose a problem when experimenting with RNA. We investigated the capabilities of nonthermal atmospheric-pressure plasmas to inactivate RNase A and studied the inactivation mechanism on a molecular level. While prolonged heating above 90 °C is required for heat inactivating RNase A, direct plasma treatment with a dielectric barrier discharge (DBD) source caused permanent inactivation within minutes. Circular dichroism spectroscopy showed that DBD-treated RNase A unfolds rapidly. Raman spectroscopy indicated methionine modifications and formation of sulfonic acid. A mass spectrometry-based analysis of the protein modifications that occur during plasma treatment over time revealed that methionine sulfoxide formation coincides with protein inactivation. Chemical reduction of methionine sulfoxides partially restored RNase A activity confirming that sulfoxidation is causal and sufficient for RNase A inactivation. Continued plasma exposure led to over-oxidation of structural disulfide bonds. Using antibodies, disulfide bond over-oxidation was shown to be a general protein inactivation mechanism of the DBD. The antibody’s heavy and light chains linked by disulfide bonds dissociated after plasma exposure. Based on their ability to inactivate proteins by oxidation of sulfur-containing amino acids and over-oxidation of disulfide bonds, DBD devices present a viable option for inactivating undesired or hazardous proteins on heat or solvent-sensitive surfaces.

  7. In-Package Inactivation of Pathogenic and Spoilage Bacteria Associated with Poultry Using Dielectric Barrier Discharge-Cold Plasma Treatments.

    PubMed

    Rothrock, Michael J; Zhuang, Hong; Lawrence, Kurt C; Bowker, Brian C; Gamble, Gary R; Hiett, Kelli L

    2017-02-01

    The goal of this study was to test the efficacy of in-package dielectric barrier discharge-cold plasma (DBD-CP) treatment to inactivate poultry-associated spoilage (Pseudomonas fluorescens) and pathogenic (Salmonella enterica Typhimurium, Campylobacter jejuni) bacteria. Liquid cultures of the bacterial isolates were sealed within packages containing ambient air (Trial 1) or modified air (65% O2:30% CO2:5% N2; Trial 2). The packages were subjected to treatment times ranging from 30 to 180 s, and after 24 h incubation at 4 °C, bacterial titers were determined. The DBD-CP system completely inactivated the four isolates tested, although the in-package gas composition and treatment times were isolate-specific. Both C. jejuni isolates were completely inactivated between 30 s (modified air) and 120 s (ambient air), while modified air was required for the complete inactivation of S. typhimurium (90 s) and P. fluorescens (180 s). This DBD-CP system is effective for inactivating major poultry-associated spoilage and pathogenic bacteria in liquid culture, and through this study, system parameters to optimize inactivation were determined. This study demonstrates the potential for DBD-CP treatment to inactivate major bacteria of economic interest to the poultry industry, thus potentially allowing for reduced spoilage (e.g., longer shelf life) and increased safety of poultry products.

  8. Compressibility effects on the non-linear receptivity of boundary layers to dielectric barrier discharges

    NASA Astrophysics Data System (ADS)

    Denison, Marie F. C.

    The reduction of drag and aerodynamic heating caused by boundary layer transition is of central interest for the development of hypersonic vehicles. Receptivity to flow perturbation in the form of Tollmien-Schlichting (TS) wave growth often determines the first stage of the transition process, which can be delayed by depositing specific excitations into the boundary layer. Weakly ionized Dielectric Barrier Discharge (DBD) actuators are being investigated as possible sources of such excitations, but little is known today about their interaction with high-speed flows. In this framework, the first part of the thesis is dedicated to a receptivity study of laminar compressible boundary layers over a flat plate by linear stability analysis following an adjoint operator formulation, under DBD representative excitations assumed independent of flow conditions. The second part of the work concentrates on the development of a coupled plasma-Navier and Stokes solver targeted at the study of supersonic flow and compressibility effects on DBD forcing and non-parallel receptivity. The linear receptivity study of quasi-parallel compressible flows reveals several interesting features such as a significant shift of the region of maximum receptivity deeper into the flow at high Mach number and strong wave amplitude reduction compared to incompressible flows. The response to DBD relevant excitation distributions and to variations of the base flow conditions and system length scales follows these trends. Observed absolute amplitude changes and relative sensitivity modifications between source types are related to the evolution of the offset between forcing peak profile and relevant adjoint mode maximum. The analysis highlights the crucial importance of designing and placing the actuator in a way that matches its force field to the position of maximum boundary layer receptivity for the specific flow conditions of interest. In order to address the broad time and length scale spectrum

  9. Characteristics of NOx removal combining dielectric barrier discharge plasma with selective catalytic reduction by C2H5OH

    NASA Astrophysics Data System (ADS)

    Wang, Xing-Quan; Chen, Wei; Guo, Qi-Pei; Li, Yi; Lv, Guo-Hua; Sun, Xiu-Ping; Zhang, Xian-Hui; Feng, Ke-Cheng; Yang, Si-Ze

    2009-07-01

    With the assistance of dielectric barrier discharge (DBD) plasma, selective catalytic reduction of NOx by ethanol over Ag/Al2O3 catalysts was studied. Experimental results show that NOx conversion was greatly enhanced due to the presence of DBD plasma at lower temperature. By varying the DBD voltages or power in 13 kHz frequency at different temperatures, NOx conversion was increased to 40.7% from 6.4% at 176 °C, even to 66.8% from 17.3% at 200 °C. NOx conversion could even be improved to 90% at temperature above 255 °C. It was proposed that nonthermal plasma generated by dielectric barrier discharge reactor was very effective for oxidizing NO to NO2 under excess O2 conditions, which possesses high reactivity with C2H5OH to yield CxHyNzO compound. By reacting with CxHyNzO compound and oxygen, NOx is converted to N2 at low temperatures.

  10. CO2 Dissociation using the Versatile Atmospheric Dielectric Barrier Discharge Experiment (VADER)

    NASA Astrophysics Data System (ADS)

    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

  11. Ozone and dinitrogen monoxide production in atmospheric pressure air dielectric barrier discharge plasma effluent generated by nanosecond pulse superimposed alternating current voltage

    NASA Astrophysics Data System (ADS)

    Takashima, Keisuke; Kaneko, Toshiro

    2017-06-01

    The effects of nanosecond pulse superposition to alternating current voltage (NS + AC) on the generation of an air dielectric barrier discharge (DBD) plasma and reactive species are experimentally studied, along with measurements of ozone (O3) and dinitrogen monoxide (N2O) in the exhausted gas through the air DBD plasma (air plasma effluent). The charge-voltage cycle measurement indicates that the role of nanosecond pulse superposition is to induce electrical charge transport and excess charge accumulation on the dielectric surface following the nanosecond pulses. The densities of O3 and N2O in NS + AC DBD are found to be significantly increased in the plasma effluent, compared to the sum of those densities generated in NS DBD and AC DBD operated individually. The production of O3 and N2O is modulated significantly by the phase in which the nanosecond pulse is superimposed. The density increase and modulation effects by the nanosecond pulse are found to correspond with the electrical charge transport and the excess electrical charge accumulation induced by the nanosecond pulse. It is suggested that the electrical charge transport by the nanosecond pulse might result in the enhancement of the nanosecond pulse current, which may lead to more efficient molecular dissociation, and the excess electrical charge accumulation induced by the nanosecond pulse increases the discharge coupling power which would enhance molecular dissociation.

  12. Study on the mode-transition of nanosecond-pulsed dielectric barrier discharge between uniform and filamentary by controlling pressures and pulse repetition frequencies

    NASA Astrophysics Data System (ADS)

    Yu, Sizhe; Lu, Xinpei

    2016-09-01

    We investigate the temporally resolved evolution of the nanosecond pulsed dielectric barrier discharge (DBD) in a moderate 6mm gap under various pressures and pulse repetition frequencies (PRFs) by intensified charge-coupled device (ICCD) images, using synthetic air and its components oxygen and nitrogen. It is found that the pressures are very different when the DBD mode transits between uniform and filamentary in air, oxygen, and nitrogen. The PRFs can also obviously affect the mode-transition. The transition mechanism in the pulsed DBD is not Townsend-to-streamer, which is dominant in the traditional alternating-voltage DBDs. The pulsed DBD in a uniform mode develops in the form of plane ionization wave, due to overlap of primary avalanches, while the increase in pressure disturbs the overlap and DBD develops in streamer instead, corresponding to the filamentary mode. Increasing the initiatory electron density by pre-ionization methods may contribute to discharge uniformity at higher pressures. We also find that the dependence of uniformity upon PRF is non-monotonic.

  13. Characterization of a DBD-Based Plasma Jet Using a Variable Pulse Width Nanosecond Pulser

    NASA Astrophysics Data System (ADS)

    Ziemba, Timothy; Picard, Julian; Prager, James; Miller, Kenneth; Carscadden, John

    2015-11-01

    Most high voltage pulsers used to drive dielectric barrier discharges (DBDs), produce a single pulse shape (width and voltage), thus making it challenging to assess the effect of pulse shape on the production of different chemical species during a discharge. Eagle Harbor Technologies, Inc. (EHT) has developed a high voltage nanosecond pulser that enables independent control of the output voltage, pulse width, and pulse repetition frequency. This pulser has been specifically designed to drive dielectric barrier discharges (DBD). EHT has used this pulser to conduct a parametric investigation of a DBD-based jet utilizing spectroscopic diagnostics. A better understanding of this parameter dependency can allow for more targeted and effective application of plasma in medical, environmental, industrial, and other applications. Results comparing DBD voltage and current waveforms with plasma spectrographic measurements will be presented.

  14. Thermal ionization instability development in air plasma generated by repetitive ns dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Starikovskiy, Andrey; Shneider, Mikhael; Marinov, Daniil; Starikovskaia, Svetlana; PU Team; LPP Team

    2013-09-01

    The aim of this paper is to study a transformation of a nanosecond discharge under conditions of high repetitive frequency in a barrier configuration of the electrodes. Nanosecond DBDs at atmospheric pressure are widely used for research in plasma medicine. At atmospheric pressure conditions the discharge develops as a set of microchannels bridging a gap between the electrodes covered with dielectric, the current in each microchannel is restricted by charging of a dielectric surface. With pressure decrease, a discharge becomes more uniform, still it is known that a slight change of a gas mixture composition, f.e. add of a fuel, may lead to significant problems with the uniformity. Estimations were made to analyze the possibility of discharge contruction due to thermal ionization instability development. We used the assumption that there is no convective cooling of the gas in the discharge cell. It was shown that NS discharge in DBD geometry is non-uniform. Initial electrical fields distribution and thermal ionization instability development form the non-uniform energy distribution in the discharge. This non-uniformity can play a key role in kinetic experiments in this type of the discharge.

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

    SciTech Connect

    Khan, Muhammad Saiful Islam; Lee, Eun-Jung; Kim, Yun-Ji

    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.

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

    NASA Astrophysics Data System (ADS)

    Khan, Muhammad Saiful Islam; Lee, Eun-Jung; Kim, Yun-Ji

    2015-10-01

    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.

  17. Preparation and characterization of ZnO-deposited DBD plasma-treated PP packaging film with antibacterial activities

    NASA Astrophysics Data System (ADS)

    Paisoonsin, Sutida; Pornsunthorntawee, Orathai; Rujiravanit, Ratana

    2013-05-01

    Zinc oxide (ZnO)-deposited polypropylene (PP) packaging film was prepared with the aid of dielectric barrier discharge (DBD) plasma treatment. The surface hydrophilicity of PP film was found to increase after the DBD plasma treatment due to the presence of oxygen-containing functional groups on the DBD plasma-treated PP surface. Although the surface roughness of the DBD plasma-treated PP film gradually increased with increasing plasma treatment time, the DBD plasma treatment insignificantly affected the mechanical properties of the PP film. The DBD plasma treatment time was found to be optimized at 10 s. The DBD plasma-treated PP film was further immersed in an aqueous zinc nitrate (Zn(NO3)2) solution at different concentrations before being converted to ZnO particles with the use of a 2.5 M sodium hydroxide (NaOH) solution, followed by sonication. The highest amount of ZnO deposited on the DBD plasma-treated PP surface was about 0.26 wt.% at the optimum Zn(NO3)2 concentration of 0.5 M. The ZnO-deposited DBD plasma-treated PP film showed good antibacterial activities against gram-positive Staphylococcus auerus and gram-negative Escherichia coli.

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

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

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

  19. Spectroscopic Investigation of a Dielectric Barrier Discharge Over a Wide Range of Pulse Parameters

    NASA Astrophysics Data System (ADS)

    Picard, Julian; Prager, James; Ziemba, Timothy; Miller, Kenneth E.; Hashim, Akel

    2015-09-01

    Most high voltage pulser used to drive dielectric barrier discharges (DBDs), produce a single pulse shape (width and voltage), thus making it challenging to assess the effect of pulse shape on the production of different chemical species during a discharge. Eagle Harbor Technologies (EHT), Inc. has developed a nanosecond pulser that allows for independent control of the output voltage, pulse width, and pulse repetition frequency. Through the utilization of this technology, presented here is a precise characterization of reactive species generated by the DBD under the independent variation of voltage (0-20 kV), frequency (0-20 kHz) and pulse width (20-260 ns). A better understanding of this parameter dependency can allow for more targeted and effective application of plasma in medical, environmental, industrial, and other applications.

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

    NASA Astrophysics Data System (ADS)

    Nishihara, M.; Takashima, K.; Rich, J. W.; Adamovich, I. V.

    2011-06-01

    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.

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

    SciTech Connect

    Nishihara, M.; Takashima, K.; Rich, J. W.; Adamovich, I. V.

    2011-06-15

    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.

  2. Study on the mode-transition of nanosecond-pulsed dielectric barrier discharge between uniform and filamentary by controlling pressures and pulse repetition frequencies

    NASA Astrophysics Data System (ADS)

    Yu, S.; Pei, X.; Hasnain, Q.; Nie, L.; Lu, X.

    2016-02-01

    In this paper, we investigate the temporally resolved evolution of the nanosecond pulsed dielectric barrier discharge (DBD) in a moderate 6 mm discharge gap under various pressures and pulse repetition frequencies (PRFs) by intensified charge-coupled device (ICCD) images, using dry air and its components oxygen and nitrogen. It is found that the pressures are very different when the mode transits between uniform and filamentary in air, oxygen, and nitrogen. The PRFs can also obviously affect the mode-transition. The transition mechanism in the pulsed DBD is not Townsend-to-Streamer, which is dominant in the traditional alternating-voltage DBD. The pulsed DBD in a uniform mode develops in the form of plane ionization wave due to overlap of primary avalanches, while the increase in pressure disturbs the overlap and discharge develops in streamer, corresponding to the filamentary mode. Increasing the initial electron density by pre-ionization may contribute to discharge uniformity at higher pressures. We also found that the dependence of homogeneity upon PRF is a non-monotonic one.

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

    NASA Astrophysics Data System (ADS)

    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

  4. Reactive fluxes delivered by dielectric barrier discharge filaments to slightly wounded skin

    NASA Astrophysics Data System (ADS)

    Babaeva, Natalia Yu; Kushner, Mark J.

    2013-01-01

    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. In this paper, we report on a computational study of the intersection of plasma filaments in a dielectric barrier discharge (DBD) with a small wound in human skin in the context of plasma medicine. The wound is represented as a small cut in the epidermal layer of cells. Intracellular structures and their electrical properties were incorporated into the two-dimensional computational mesh in order to self-consistently couple gas phase plasma transport with the charging of the surface of the wound. We quantify the fluxes of reactive oxygen and nitrogen species, ions and photons produced in or diffusing into the wound as might occur during the first few discharge pulses of treatment. Comparison is made to fluxes predicted by global modelling. We show that the relative location of the plasma filament with respect to the wound is important on plasma time scales (ns) for ions and photons, and for radicals directly produced by electron impact processes. On the longer-term diffusion time scales (ms) the position of the plasma filament relative to the wound is not so critical. For typical DBD conditions, the magnitude of these fluxes to the cellular surfaces corresponds to fluences of radicals nearly equal to the surface site density. These results imply that the biological reactivity is limited by reaction probabilities and not the availability of radical fluxes.

  5. Evaluation of pathogen inactivation on sliced cheese induced by encapsulated atmospheric pressure dielectric barrier discharge plasma.

    PubMed

    Yong, Hae In; Kim, Hyun-Joo; Park, Sanghoo; Alahakoon, Amali U; Kim, Kijung; Choe, Wonho; Jo, Cheorun

    2015-04-01

    Pathogen inactivation induced by atmospheric pressure dielectric barrier discharge (DBD) (250 W, 15 kHz, air discharge) produced in a rectangular plastic container and the effect of post-treatment storage time on inactivation were evaluated using agar plates and cheese slices. When agar plates were treated with plasma, populations of Escherichia coli, Salmonella Typhimurium, and Listeria monocytogenes showed 3.57, 6.69, and 6.53 decimal reductions at 60 s, 45 s, and 7 min, respectively. When the pathogens tested were inoculated on cheese slices, 2.67, 3.10, and 1.65 decimal reductions were achieved at the same respective treatment times. The post-treatment storage duration following plasma treatment potently affected further reduction in pathogen populations. Therefore, the newly developed encapsulated DBD-plasma system for use in a container can be applied to improve the safety of sliced cheese, and increasing post-treatment storage time can greatly enhance the system's pathogen-inactivation efficiency. Copyright © 2014 Elsevier Ltd. All rights reserved.

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

    PubMed

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

    2016-12-15

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

  7. Elimination of diazinon insecticide from cucumber surface by atmospheric pressure air-dielectric barrier discharge plasma.

    PubMed

    Dorraki, Naghme; Mahdavi, Vahideh; Ghomi, Hamid; Ghasempour, Alireza

    2016-12-06

    The food industry is in a constant search for new technologies to improve the commercial sterilization process of agricultural commodities. Plasma treatment may offer a novel and efficient method for pesticide removal from agricultural product surfaces. To study the proposed technique of plasma food treatment, the degradation behavior of diazinon insecticide by air-dielectric barrier discharge (DBD) plasma was investigated. The authors studied the effect of different plasma powers and treatment times on pesticide concentration in liquid form and coated on the surface of cucumbers, where the diazinon residue was analyzed with mass spectroscopy gas chromatography. Our results suggest that atmospheric pressure air-DBD plasma is potentially effective for the degradation of diazinon insecticide, and mainly depends on related operating parameters, including plasma treatment time, discharge power, and pesticide concentrations. Based on the interaction between reactive oxygen species and electrons in the plasma with the diazinon molecule, two degradation pathway of diazinon during plasma treatment are proposed. It was also found that produced organophosphate pesticides are harmless and less hazardous compounds than diazinon.

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

    PubMed

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

    2013-05-23

    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 lung normal cells. The mitochondrial vulnerability to reactive species in H460 may induce distinctively selective responses. Differential mitochondrial membrane potential decrease, mitochondrial enzymatic dysfunction, and mitochondrial morphological alteration are exhibited in two cell lines. These results suggest the nonthermal plasma treatment as an efficacious modality in lung cancer therapy.

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

    PubMed Central

    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 lung normal cells. The mitochondrial vulnerability to reactive species in H460 may induce distinctively selective responses. Differential mitochondrial membrane potential decrease, mitochondrial enzymatic dysfunction, and mitochondrial morphological alteration are exhibited in two cell lines. These results suggest the nonthermal plasma treatment as an efficacious modality in lung cancer therapy. PMID:23703387

  10. Destruction of Gaseous Styrene with a Low-Temperature Plasma Induced by a Tubular Multilayer Dielectric Barrier Discharge

    NASA Astrophysics Data System (ADS)

    Zhang, Jiahui; Liu, Juanjuan; Zhang, Renxi; Hou, Huiqi; Chen, Shanping; Zhang, Yi

    2015-01-01

    The destruction of gaseous styrene was studied using a low-temperature plasma induced by tubular multilayer dielectric barrier discharge (DBD). The results indicate that the applied voltage, gas flow rate, inlet styrene concentration and reactor configuration play important roles in styrene removal efficiency (ηstyrene) and energy yield (EY). Values of ηstyrene and EY reached 96% and 15567 mg/kWh when the applied voltage, gas flow rate, inlet styrene concentration and layers of quartz tubes were set at 10.8 kV, 5.0 m/s, 229 mg/m3 and 5 layers, respectively. A qualitative analysis of the byproducts and a detailed discussion of the reaction mechanism are also presented. The results could facilitate industrial applications of the new DBD reactor for waste gas treatment.

  11. Origin of activated combustion in steady-state premixed burner flame with superposition of dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Zaima, Kazunori; Akashi, Haruaki; Sasaki, Koichi

    2016-01-01

    The objective of this work is to understand the mechanism of plasma-assisted combustion in a steady-state premixed burner flame. We examined the spatiotemporal variation of the density of atomic oxygen in a premixed burner flame with the superposition of dielectric barrier discharge (DBD). We also measured the spatiotemporal variations of the optical emission intensities of Ar and OH. The experimental results reveal that atomic oxygen produced in the preheating zone by electron impact plays a key role in the activation of combustion reactions. This understanding is consistent with that described in our previous paper indicating that the production of “cold OH(A2Σ+)” via CHO + O → OH(A2Σ+) + CO has the sensitive response to the pulsed current of DBD [K. Zaima and K. Sasaki, Jpn. J. Appl. Phys. 53, 110309 (2014)].

  12. Development of dielectric barrier discharge-type ozone generator constructed with piezoelectric transformers: effect of dielectric electrode materials on ozone generation

    NASA Astrophysics Data System (ADS)

    Teranishi, Kenji; Shimomura, Naoyuki; Suzuki, Susumu; Itoh, Haruo

    2009-11-01

    The dependence of ozone generation on the types of dielectric electrode material has been investigated using an ozone generator constructed with the piezoelectric transformer developed in our laboratory. The ozone generator is based on the excitation of the dielectric barrier discharge (DBD), which has the advantage of a compact configuration for generating ozone. Four kinds of dielectric materials are prepared for dielectric barrier electrodes. Electrical properties of the DBD and the ozone generation characteristics are investigated for the different dielectric materials. Differences in the discharge mode among the barrier electrode materials are recognized and discussed on the basis of the results of the Lissajous figures and voltage-current waveforms. During the continuous running of the generator, a temporal decrease in ozone concentration is observed owing to the temperature increase inside the reactor. Although the ozone generation characteristics are influenced by many properties of dielectrics, two important factors for achieving high-efficiency ozone generation are identified in this study. One is the use of a high-thermal conductivity material for the dielectric electrode, which functions well as a heat sink for transferring the generated heat to the outside through the material. The other factor is the control of the discharge mode. Our results show that the discharge mode that is considered as Townsend-like DBD is suitable for high-efficiency ozone generation.

  13. Studying barrier-discharge-stimulated plasmachemical reactions

    NASA Astrophysics Data System (ADS)

    Malanichev, V. E.; Malashin, M. V.; Moshkunov, S. I.; Nebogatkin, S. V.; Khomich, V. Yu.; Shmelev, V. M.

    2017-05-01

    Barrier-discharge stimulation of chemical reactions has been studied in the case of methane oxidation by atmospheric oxygen with the formation of carbon monoxide and hydrogen. Experiments in a plasmachemical reactor demonstrated the possibility of increasing the yield of synthesis gas (syngas) by means of plasma pretreatment of the initial mixture of air and methane in a 7: 1 ratio at atmospheric pressure. The output-gas composition was determined by gas chromatography. It is established that the plasma-discharge treatment of the initial gas mixture leads to a 15% increase in the amount of syngas at the reactor output and increases the reaction selectivity with respect to hydrogen and carbon monoxide by 3.2 and 6.5%, respectively.

  14. Interactions between surface discharges induced by volume discharges in a dielectric barrier discharge system

    SciTech Connect

    Gao, Yenan; Dong, Lifang Zhao, Longhu; Wang, Yongjie; Pan, Yuyang; Li, Ben

    2014-10-15

    The interaction between micro-discharges involved in surface discharges (SDs) is studied in dielectric barrier discharge system. Instantaneous images taken by high speed cameras show that the SDs are induced by volume discharges (VDs). They cannot cross the midperpendicular of two neighbouring volume charges at low voltage while they stretch along it at high voltage, indicating that there is interaction between SDs. The differences of plasma parameters between SD and VD are studied by optical emission spectroscopy. The simulation of the electric fields of the wall charges accumulated by VD further confirms the existence of the interaction.

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

    NASA Astrophysics Data System (ADS)

    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.

  16. Atmospheric Pressure Non-Thermal Plasma Activation of CO2 in a Packed-Bed Dielectric Barrier Discharge Reactor.

    PubMed

    Mei, Danhua; Tu, Xin

    2017-08-17

    Direct conversion of CO2 into CO and O2 is performed in a packed-bed dielectric barrier discharge (DBD) non-thermal plasma reactor at low temperatures and atmospheric pressure. The maximum CO2 conversion of 22.6 % is achieved when BaTiO3 pellets are fully packed into the discharge gap. The introduction of γ-Al2 O3 or 10 wt % Ni/γ-Al2 O3 catalyst into the BaTiO3 packed DBD reactor increases both CO2 conversion and energy efficiency of the plasma process. Packing γ-Al2 O3 or 10 wt % Ni/γ-Al2 O3 upstream of the BaTiO3 bed shows higher CO2 conversion and energy efficiency compared with that of mid- or downstream packing modes because the reverse reaction of CO2 conversion-the recombination of CO and O to form CO2 -is more likely to occur in mid- and downstream modes. Compared with the γ-Al2 O3 support, the coupling of the DBD with the Ni catalyst shows a higher CO2 conversion, which can be attributed to the presence of Ni active species on the catalyst surface. The argon plasma treatment of the reacted Ni catalyst provides extra evidence to confirm the role of Ni active species in the conversion of CO2 . © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    NASA Technical Reports Server (NTRS)

    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.

  18. Formation mechanism of dot-line square superlattice pattern in dielectric barrier discharge

    SciTech Connect

    Liu, Weibo; Dong, Lifang E-mail: pyy1616@163.com; Wang, Yongjie; Zhang, Xinpu; Pan, Yuyang E-mail: pyy1616@163.com

    2014-11-15

    We investigate the formation mechanism of the dot-line square superlattice pattern (DLSSP) in dielectric barrier discharge. The spatio-temporal structure studied by using the intensified-charge coupled device camera shows that the DLSSP is an interleaving of three different subpatterns in one half voltage cycle. The dot square lattice discharges first and, then, the two kinds of line square lattices, which form square grid structures discharge twice. When the gas pressure is varied, DLSSP can transform from square superlattice pattern (SSP). The spectral line profile method is used to compare the electron densities, which represent the amounts of surface charges qualitatively. It is found that the amount of surface charges accumulated by the first discharge of DLSSP is less than that of SSP, leading to a bigger discharge area of the following discharge (lines of DLSSP instead of halos of SSP). The spatial distribution of the electric field of the surface charges is simulated to explain the formation of DLSSP. This paper may provide a deeper understanding for the formation mechanism of complex superlattice patterns in DBD.

  19. Effect of Water Vapor on Toluene Removal in Catalysis-DBD Plasma Reactors

    NASA Astrophysics Data System (ADS)

    Wang, Jingting; Cao, Xu; Zhang, Renxi; Gong, Ting; Hou, Huiqi; Chen, Shanping; Zhang, Ruina

    2016-04-01

    The experiment was carried out in a cylindrical dielectric barrier discharge (DBD) reactor assisted with a catalyst to decompose toluene under different humidity. In order to explore the synergistic effect on removing toluene in the catalysis-DBD reactor, this paper investigated the decomposition efficiency and the energy consumption in the catalysis-DBD and the non-catalyst DBD reactors under different humidity. The results showed that the catalysis-DBD reactor had a better performance than the non-catalysis one at the humidity ratio of 0.4%, and the removal efficiency of toluene could reach 88.6% in the catalysis-DBD reactor, while it was only 59.9% in the non-catalytic reactor. However, there was no significant difference in the removal efficiency of toluene between the two reactors when the humidities were 1.2% and 2.4%. Additionally, the degradation products were also analyzed in order to gain a better understanding of the mechanism of decomposing toluene in a catalysis-DBD reactor. supported by the Key Project which is sponsored by the Science and Technology Commission of Shanghai Municipality (No. 13231201903), the Key Programs for Science and Technology Development sponsored by the Science and Technology Commission of Shanghai Municipality (Nos. 13231201901 and 14DZ1208401), and the Key Project sponsored by the State-owned Assets Supervision and Administration Commission of Shanghai, China (No. 2013019)

  20. Parameter Optimization for Enhancement of Ethanol Yield by Atmospheric Pressure DBD-Treated Saccharomyces cerevisiae

    NASA Astrophysics Data System (ADS)

    Dong, Xiaoyu; Yuan, Yulian; Tang, Qian; Dou, Shaohua; Di, Lanbo; Zhang, Xiuling

    2014-01-01

    In this study, Saccharomyces cerevisiae (S. cerevisiae) was exposed to dielectric barrier discharge plasma (DBD) to improve its ethanol production capacity during fermentation. Response surface methodology (RSM) was used to optimize the discharge-associated parameters of DBD for the purpose of maximizing the ethanol yield achieved by DBD-treated S. cerevisiae. According to single factor experiments, a mathematical model was established using Box-Behnken central composite experiment design, with plasma exposure time, power supply voltage, and exposed-sample volume as impact factors and ethanol yield as the response. This was followed by response surface analysis. Optimal experimental parameters for plasma discharge-induced enhancement in ethanol yield were plasma exposure time of 1 min, power voltage of 26 V, and an exposed sample volume of 9 mL. Under these conditions, the resulting yield of ethanol was 0.48 g/g, representing an increase of 33% over control.

  1. Atomic oxygen dynamics in an air dielectric barrier discharge: a combined diagnostic and modeling approach

    NASA Astrophysics Data System (ADS)

    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.

  2. Degradation of aqueous 3,4-dichloroaniline by a novel dielectric barrier discharge plasma reactor.

    PubMed

    Feng, Jingwei; Liu, Runlong; Chen, Pei; Yuan, Shoujun; Zhao, Dayong; Zhang, Jibiao; Zheng, Zheng

    2015-03-01

    Degradation of aqueous 3,4-dichloroaniline (3,4-DCA) was conducted in a novel dielectric barrier discharge (DBD) plasma reactor. The factors affecting the degradation efficiency of 3,4-DCA and the degradation mechanism of 3,4-DCA were investigated. The experimental results indicated that the degradation efficiency of 3,4-DCA increased with increasing input power intensity, and the degradation of 3,4-DCA by the novel DBD plasma reactor fitted pseudo-first-order kinetics. Higher degradation efficiency of 3,4-DCA was observed in acidic conditions. The degradation efficiency of 3,4-DCA, the removal rate of total organic carbon (TOC), and the detected Cl(-) increased dramatically with adding Fe(2+) or Fe(3+). Degradation of 3,4-DCA could be accelerated or inhibited in the presence of H2O2 depending on the dosage. Several degradation intermediates of 3,4-DCA such as 1,2-dichlorobenzene, 2-chloro-1,4-benzoquinone, 3,4-dichlorophenyl isocyanate, 2-chlorohydroquinone, 3,4-dichloronitrobenzene, and 3,4-dichlorophenol were identified by gas chromatography mass spectrometry (GC-MS) analysis. Based on the identification of aromatic intermediates, acetic acid, formic acid, oxalic acid, and Cl(-) released, a possible mineralization pathway of 3,4-DCA was proposed.

  3. Experimental Study on Inactivation of Bacterial Endotoxin by Using Dielectric Barrier Discharge

    NASA Astrophysics Data System (ADS)

    Shi, Xingmin; Li, Yaxi; Zhang, Guanjun; Ma, Yue; Shao, Xianjun

    2011-12-01

    The low-temperature plasma (LTP) generated by dielectric barrier discharge (DBD) was used to sterilize the E.coli endotoxin, which is usually difficult to kill by traditional methods. Three different concentrations of bacterial endotoxin (1 EU/mL, 0.5 EU/mL and 0.25 EU/mL) were treated by LTP for different time (20 s, 40 s and 60 s). Tachypleus amebocyte lysate (TAL) method was employed to detect the concentration variation of bacterial endotoxin before and after the plasma treatment, and endotoxic shock mice model was used to evaluate the inactivation effects of LTP on endotoxin for further study. Experimental results demonstrated that, DBD plasma can inactivate the bacterial endotoxin quickly and effectively, and when the LTP treatment time was increased, the concentrations of bacterial endotoxin decreased gradually (after 60 s plasma treatment, its inactivation effect was beyond the Chinese pharmacopoeia standard), and the average survival time of mice gradually extended. The possible inactivation mechanisms are proposed to be related to reactive oxygen species (ROSs).

  4. Dielectric barrier discharge-based investigation and analysis of wastewater treatment and pollutant removal.

    PubMed

    Ramdani, N; Lousdad, A; Tilmatine, A; Nemmich, S

    2016-01-01

    Current research reveals that the oxidation by ozone is considered as an effective solution and offers irrefutable advantages in wastewater treatment. It is also well known that ozone is used to treat different types of water due to its effectiveness in water purification and for its oxidation potential. This process of ozonation is becoming progressively an alternative technology and is inscribed in a sustainable development perspective in Algeria. In this regards, the present paper investigates the wastewater treatment process by ozone produced by dielectric barrier discharge (DBD) under high potential. Three (DBD) ozone generators of cylindrical form have been used, at a laboratory scale, for treating collected samples from the wastewater treatment plant (WWTP) of the city of Sidi-Bel-Abbes located in the west of Algeria. Our experimental results reveal the efficiency of this type of treatment on the basis of the physicochemical analysis (pH, turbidity, chemical oxygen demand, biological oxygen demand, heavy metals) and microbial analysis downstream of the WWTP, which showed a high rate of elimination of all the parameters.

  5. Concentration of atomic hydrogen in a dielectric barrier discharge measured by two-photon absorption fluorescence

    NASA Astrophysics Data System (ADS)

    Dvořák, P.; Talába, M.; Obrusník, A.; Kratzer, J.; Dědina, J.

    2017-08-01

    Two-photon absorption laser-induced fluorescence (TALIF) was utilized for measuring the concentration of atomic hydrogen in a volume dielectric barrier discharge (DBD) ignited in mixtures of Ar, H2 and O2 at atmospheric pressure. The method was calibrated by TALIF of krypton diluted in argon at atmospheric pressure, proving that three-body collisions had a negligible effect on quenching of excited krypton atoms. The diagnostic study was complemented with a 3D numerical model of the gas flow and a zero-dimensional model of the chemistry in order to better understand the reaction kinetics and identify the key pathways leading to the production and destruction of atomic hydrogen. It was determined that the density of atomic hydrogen in Ar-H2 mixtures was in the order of 1021 m-3 and decreased when oxygen was added into the gas mixture. Spatially resolved measurements and simulations revealed a sharply bordered region with low atomic hydrogen concentration when oxygen was added to the gas mixture. At substoichiometric oxygen/hydrogen ratios, this H-poor region is confined to an area close to the gas inlet and it is shown that the size of this region is not only influenced by the chemistry but also by the gas flow patterns. Experimentally, it was observed that a decrease in H2 concentration in the feeding Ar-H2 mixture led to an increase in H production in the DBD.

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

    NASA Astrophysics Data System (ADS)

    Sasaki, Shota; Kanzaki, Makoto; Kaneko, Toshiro

    2013-09-01

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

  7. CO and byproduct formation during CO₂ reduction in dielectric barrier discharges

    SciTech Connect

    Brehmer, F.; Welzel, S.; Sanden, M. C. M. van de; Engeln, R.

    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.

  8. Electrical and optical characterization of an atmospheric pressure, uniform, large-area processing, dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Zeniou, A.; Puač, N.; Škoro, N.; Selaković, N.; Dimitrakellis, P.; Gogolides, E.; Petrović, Z. Lj

    2017-04-01

    A printed-circuit-board (PCB) based atmospheric pressure dielectric barrier discharge (DBD) capable of uniform processing over a large area was constructed consisting of two parallel plates. The first perforated plate is comprised of four layers: a RF powered metal layer, a polymeric dielectric layer, a floating metal grid and another dielectric layer. The second, grounded, plate was fluorine doped tin oxide (FTO) glass plate with surface of 100  ×  100 mm2 and thickness of 2 mm. The PCB based atmospheric pressure DBD was characterized by (a) measuring electrical characteristics of the device using derivative I–V probes, (b) ICCD imaging and (c) optical emission spectroscopy (OES). Optical and electrical characteristics, as well as plasma uniformity were measured by changing He flow rate and input power, while keeping the gap between the PCB and the FTO glass plate ground electrode constant at 2 mm. The plasma uniformity strongly depends on the applied power and on the flow rate of the buffer gas. When increasing the flow rate, the intensity of the nitrogen-dominated emission drops, while emission of helium and oxygen lines increases. The source allows low temperature, uniform plasma operation over a wide area of 100  ×  100 mm2, which could be essential for numerous applications. Examples of etching rate and hydrophilization are demonstrated.

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

    NASA Astrophysics Data System (ADS)

    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.

  10. Decolorization of reactive textile dyes using water falling film dielectric barrier discharge.

    PubMed

    Dojčinović, Biljana P; Roglić, Goran M; Obradović, Bratislav M; Kuraica, Milorad M; Kostić, Mirjana M; Nešić, Jelena; Manojlović, Dragan D

    2011-08-30

    Decolorization of reactive textile dyes Reactive Black 5, Reactive Blue 52, Reactive Yellow 125 and Reactive Green 15 was studied using advanced oxidation processes (AOPs) in a non-thermal plasma reactor, based on coaxial water falling film dielectric barrier discharge (DBD). Used initial dye concentrations in the solution were 40.0 and 80.0mg/L. The effects of different initial pH of dye solutions, and addition of homogeneous catalysts (H(2)O(2), Fe(2+) and Cu(2+)) on the decolorization during subsequent recirculation of dye solution through the DBD reactor, i.e. applied energy density (45-315kJ/L) were studied. Influence of residence time was investigated over a period of 24h. Change of pH values and effect of pH adjustments of dye solution after each recirculation on the decolorization was also tested. It was found that the initial pH of dye solutions and pH adjustments of dye solution after each recirculation did not influence the decolorization. The most effective decolorization of 97% was obtained with addition of 10mM H(2)O(2) in a system of 80.0mg/L Reactive Black 5 with applied energy density of 45kJ/L, after residence time of 24h from plasma treatment. Toxicity was evaluated using the brine shrimp Artemia salina as a test organism. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. Stabilizing a blasius boundary layer with dielectric barrier discharge plasma actuation: experimental characterization

    NASA Astrophysics Data System (ADS)

    Szulga, N.; Vermeersch, O.; Forte, M.; Casalis, G.

    2017-06-01

    This paper presents an experimental characterization of Dielectric Barrier Discharge (DBD) plasma actuation on a two-dimensional (2D) boundary layer around a §at plate using both Laser Doppler Anemometry (LDA) and hot wire probings. The experiments are conducted in a subsonic wind tunnel at a free-stream velocity U∞ = 35 m/s for a single DBD actuator and several electrical parameters. Hot wire probings are used to quantify the transition delay and mean velocity pro¦les far enough from the plasma region, while mean velocity pro¦le inside the plasma extent are measured using LDA after the method has been validated from a comparison with hot wire measurements. Measurements inside the plasma extent allow to quantify the ionic wind contribution to the actuated mean velocity pro¦les in a case where the transition is delayed by the actuator. A maximal ionic wind of 7 m/s is found to be added 2 mm downstream the actuator for a consumed electrical power of 80 W/m.

  12. Conversion of carbon dioxide to carbon monoxide by pulse dielectric barrier discharge plasma

    NASA Astrophysics Data System (ADS)

    Wang, Taobo; Liu, Hongxia; Xiong, Xiang; Feng, Xinxin

    2017-01-01

    The conversion of carbon dioxide (CO2) to carbon monoxide (CO) was investigated in a non-thermal plasma dielectric barrier discharge (DBD) reactor, and the effects of different process conditions on the CO2 conversion were investigated. The results showed that the increase of input power could optimize the conversion of CO2 to CO. The CO2 conversion and CO yield were negatively correlated with the gas flow rate, but there was an optimum gas flow rate, that made the CO selectivity best. The carrier gas (N2, Ar) was conducive to the conversion of CO2, and the effect of N2 as carrier gas was better than Ar. The conversion of CO2 to CO was enhanced by addition of the catalyst (5A molecular sieve).

  13. Solubilization of Single-Walled Carbon Nanotubes Using Ozone Generated by Dielectric Barrier Discharge

    NASA Astrophysics Data System (ADS)

    Sun, Wei; Khaled, Usama; Tomita, Hironari; Li, Zhenyu; Imasaka, Kiminobu; Suehiro, Junya

    2010-05-01

    This paper describes effects of ozone (O3) concentration on water-solubility of single-walled carbon nanotubes (SWCNTs). Ozone was generated by dielectric barrier discharge (DBD) in atmospheric air with the maximum concentration of 220 ppm. Water solubility of ozone-treated SWCNTs, which was evaluated by optical absorbance of the SWCNT suspension, increased with ozone treatment time and reached the maximum in 60 min. The dispersed SWCNTs suspension was stable even after two months of the ozone treatment. Fourier transform infrared (FTIR) spectroscopy and Raman spectra analysis revealed that SWCNTs surface was functionalized with chemical group such as -COO- after the ozone treatment. The longer ozone treatment introduced more functional groups and decreased zeta potential of the SWCNT surface, which improved water-solubility of the SWCNTs due to electrostatic repulsion force between them. It was also found that the ozone treatment induced morphological changes of SWCNTs.

  14. Concentric superlattice pattern in dielectric barrier discharge

    SciTech Connect

    Feng, Jianyu; Dong, Lifang Wei, Lingyan; Fan, Weili; Li, Caixia; Pan, Yuyang

    2016-09-15

    The concentric superlattice pattern with three sub-lattices is observed in the dielectric barrier discharge in air/argon for the first time. Its spatiotemporal structure investigated by an intensified charge-coupled device shows that it is an interleaving of three different sub-lattices, which are concentric-ring, concentric-framework, and concentric-dot, respectively. The images of single-frame indicate that the concentric-ring and concentric-framework are composed of individual filaments. By using the optical emission spectrum method, it is found that plasma parameters of the concentric-dot are different from those of the concentric-ring and concentric-framework. The spatiotemporal dynamics of the concentric superlattice pattern is dependent upon the effective field of the distribution of the wall charges field and the applied field.

  15. Concentric superlattice pattern in dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Feng, Jianyu; Dong, Lifang; Wei, Lingyan; Fan, Weili; Li, Caixia; Pan, Yuyang

    2016-09-01

    The concentric superlattice pattern with three sub-lattices is observed in the dielectric barrier discharge in air/argon for the first time. Its spatiotemporal structure investigated by an intensified charge-coupled device shows that it is an interleaving of three different sub-lattices, which are concentric-ring, concentric-framework, and concentric-dot, respectively. The images of single-frame indicate that the concentric-ring and concentric-framework are composed of individual filaments. By using the optical emission spectrum method, it is found that plasma parameters of the concentric-dot are different from those of the concentric-ring and concentric-framework. The spatiotemporal dynamics of the concentric superlattice pattern is dependent upon the effective field of the distribution of the wall charges field and the applied field.

  16. Influence of the gap size and dielectric constant of the packing on the plasma discharge in a packed bed dielectric barrier discharge reactor: a fluid modeling study

    NASA Astrophysics Data System (ADS)

    van Laer, Koen; Bogaerts, Annemie

    2016-09-01

    Packed bed dielectric barrier discharge (DBD) reactors have proven to be very useful sources of non-thermal plasma for a wide range of applications, of which the environmental applications have received most attention in recent years. Compared to an empty DBD reactor, a packing was introduced to either enhance the energy efficiency of the process, or, if the packing is catalytically active, steer the process towards a preferred end product. A wide range of geometries, bead sizes and bead materials have been tested experimentally in the past. However, since experimental diagnostics become more difficult with a packing present, a computational study is proposed to gain more insight. Using COMSOL's built in plasma module, a 2D axisymmetric fluid model is developed to study the influence of the gap size and the dielectric constant (ɛ) of the packing. Helium is used as discharge gas, at atmospheric pressure and room temperature. By decreasing the gas gap, the electric field strength is enhanced, resulting in a higher number of current peaks per half cycle of applied rf potential. Increasing ɛ also enhances the electric field strength. However, after a certain ɛ, its influence saturates. The electric field strength will no longer increase, leaving the discharge behavior unchanged.

  17. Precise energy and temperature measurements in dielectric barrier discharges at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Archambault-Caron, Mylène; Gagnon, Hervé; Nisol, Bernard; Piyakis, Konstantinos; Wertheimer, Michael R.

    2015-08-01

    A specially designed dielectric barrier discharge (DBD) cell and associated equipment has been used to carry out precise measurements of electrical energy, {{E}\\text{g}} , dissipated per discharge cycle of the applied ac voltage, Va over the frequency range 5  ⩽  f   ⩽  50 kHz. Twin pairs of several different dielectric materials (2.54 cm diameter discs, thicknesses = 2.0 or ca. 0.1 mm) with relative permittivities between 2.1  ⩽  K{{'}{}}   ⩽  9.5 were used as dielectric barriers in DBDs of four different gases: He, Ne, Ar and N2. Much of the work relates to the study of atmospheric pressure glow discharge (APGD) plasma in flowing He gas; five separate thermometers (including fiber-optic probes immune to high voltage and high-frequency electromagnetic fields) have enabled us to perform a detailed calorimetric (heat balance) investigation in He APGD, believed to be the first of its kind. Fair agreement in the overall energy balance, which includes vacuum ultraviolet (VUV) light emission, lends strong support to the validity of both measurements and methodology. The latter includes refined algorithms that permit rapid data acquisition and processing. The present results are compared with literature, allowing several important conclusions/recommendations to emerge.

  18. The effect of oxygen and water vapor on nitric oxide conversion with a dielectric barrier discharge reactor

    SciTech Connect

    Yin, S.E.; Sun, B.M.; Gao, X.D.; Xiao, H.P.

    2009-12-15

    The effect of O{sub 2} and H{sub 2}O vapor on the Nitric oxide (NO) removal rate, the NO{sub 2} generation rate and the discharge characteristics were investigated using the dielectric barrier discharge (DBD) reactor at 1 atm pressure and at room temperature (20{sup o}). The results showed that the O{sub 2} present in the flue gas always hampered the removal of NO and the generation of N{sub 2}O, but that the O{sub 2} could enhance the generation of NO{sub 2} in the NO/N{sub 2}/O{sub 2} mixtures. Furthermore, with the increase of oxygen, the average discharge current gradually decreases in the reactor. The H{sub 2}O present in N-2/NO hindered the removal of NO and the generation of NO{sub 2} but had no impact on the average discharge current in the reactor in the NO/N{sub 2}/H{sub 2}O mixtures in which the HNO{sub 2} and HNO{sub 3} was detected. The energy efficiency of the DBD used to remove the NO from the flue gas was also estimated.

  19. Altered Antioxidant System Stimulates Dielectric Barrier Discharge Plasma-Induced Cell Death for Solid Tumor Cell Treatment

    PubMed Central

    Park, Daehoon; Choi, Eun H.

    2014-01-01

    This study reports the experimental findings and plasma delivery approach developed at the Plasma Bioscience Research Center, Korea for the assessment of antitumor activity of dielectric barrier discharge (DBD) for cancer treatment. Detailed investigation of biological effects occurring after atmospheric pressure non-thermal (APNT) plasma application during in vitro experiments revealed the role of reactive oxygen species (ROS) in modulation of the antioxidant defense system, cellular metabolic activity, and apoptosis induction in cancer cells. To understand basic cellular mechanisms, we investigated the effects of APNT DBD plasma on antioxidant defense against oxidative stress in various malignant cells as well as normal cells. T98G glioblastoma, SNU80 thyroid carcinoma, KB oral carcinoma and a non-malignant HEK293 embryonic human cell lines were treated with APNT DBD plasma and cellular effects due to reactive oxygen species were observed. Plasma significantly decreased the metabolic viability and clonogenicity of T98G, SNU80, KB and HEK293 cell lines. Enhanced ROS in the cells led to death via alteration of total antioxidant activity, and NADP+/NADPH and GSH/GSSG ratios 24 hours (h) post plasma treatment. This effect was confirmed by annexin V-FITC and propidium iodide staining. These consequences suggested that the failure of antioxidant defense machinery, with compromised redox status, might have led to sensitization of the malignant cells. These findings suggest a promising approach for solid tumor therapy by delivering a lethal dose of APNT plasma to tumor cells while sparing normal healthy tissues. PMID:25068311

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

    NASA Astrophysics Data System (ADS)

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

    2017-03-01

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

  1. Enhanced degradation of perfluorooctanoic acid using dielectric barrier discharge with La/Ce-doped TiO2.

    PubMed

    Li, Shanping; Wang, Xiaoping; Liu, Lijun; Guo, Yongbo; Mu, Qinglin; Mellouki, Abdelwahid

    2017-06-01

    A synergistic system of dielectric barrier discharge (DBD) combined with La/Ce-TiO2 was developed to investigate the decomposition performance of the environmentally persistent perfluorooctanoic acid (PFOA). The La/Ce-TiO2 was modified by sol-gel method and characterized by XRD, SEM, and energy dispersive X-ray. The effects of PFOA concentration, applied voltage, initial pH, liquid conductivity, and additives on the removal rate of PFOA were explored. The results showed that the La/Ce-TiO2 exhibited excellent catalytic effects on PFOA degradation in DBD system. When the applied voltage, PFOA concentration, pH value, and solution volume were 75 V, 100 mg/L, 3.63, and 1000 mL, respectively, the removal efficiency of PFOA was up to 97.5% by adding La4Ce1-TiO2 in DBD. The corresponding defluorination ratio, TOC removal, and decomposition yield were 62.2%, 57.3%, and 37 g/kWh, respectively. Furthermore, five main intermediates including CF3(CF2)6H, CF3(CF2)5COOH, CF3(CF2)5COH, CF3(CF2)4COOH, and CF3CF2CF3 were identified with LC-MS, and the degradation pathways of PFOA were proposed. The degradation mechanisms revealed that hydroxyl radicals play a significant role in the degradation of PFOA in the synergistic system.

  2. The changes in electrical and interfacial properties of polyimide exposed to dielectric barrier discharge in SF₆ medium.

    PubMed

    Alisoy, Hafiz Z; Koseoglu, Murat

    2013-01-01

    The formation mechanism of space charges in polyimide (PI) which was exposed to dielectric barrier discharge (DBD) in SF6 medium and the effects of the space charges on interfacial and electrical properties of PI were investigated. The variation of normalized surface charge density on PI sample was calculated and illustrated for different DBD exposure times. The surface potential was measured to determine the effect of the space charges on the sample. Then, the contact angle values were measured to obtain the relation between the surface energy and the surface charge density. The expressions for the total charge and the concentration of trapped electrons were derived by using Poisson and continuity equations at stationary state. The space charges were determined experimentally by using thermally stimulated depolarization current (TSDC) method. Also, SEM image and FTIR spectrum of virgin and treated samples were presented to observe the structural variations. It was seen that the approach for the formation mechanism of the space charges agreed with the experimental data. However, it was concluded particularly for the short-time DBD treatments that the space charges accumulated in the sample should be considered besides the effects of surface functionalization in the determination of the surface energy.

  3. Altered antioxidant system stimulates dielectric barrier discharge plasma-induced cell death for solid tumor cell treatment.

    PubMed

    Kaushik, Nagendra K; Kaushik, Neha; Park, Daehoon; Choi, Eun H

    2014-01-01

    This study reports the experimental findings and plasma delivery approach developed at the Plasma Bioscience Research Center, Korea for the assessment of antitumor activity of dielectric barrier discharge (DBD) for cancer treatment. Detailed investigation of biological effects occurring after atmospheric pressure non-thermal (APNT) plasma application during in vitro experiments revealed the role of reactive oxygen species (ROS) in modulation of the antioxidant defense system, cellular metabolic activity, and apoptosis induction in cancer cells. To understand basic cellular mechanisms, we investigated the effects of APNT DBD plasma on antioxidant defense against oxidative stress in various malignant cells as well as normal cells. T98G glioblastoma, SNU80 thyroid carcinoma, KB oral carcinoma and a non-malignant HEK293 embryonic human cell lines were treated with APNT DBD plasma and cellular effects due to reactive oxygen species were observed. Plasma significantly decreased the metabolic viability and clonogenicity of T98G, SNU80, KB and HEK293 cell lines. Enhanced ROS in the cells led to death via alteration of total antioxidant activity, and NADP+/NADPH and GSH/GSSG ratios 24 hours (h) post plasma treatment. This effect was confirmed by annexin V-FITC and propidium iodide staining. These consequences suggested that the failure of antioxidant defense machinery, with compromised redox status, might have led to sensitization of the malignant cells. These findings suggest a promising approach for solid tumor therapy by delivering a lethal dose of APNT plasma to tumor cells while sparing normal healthy tissues.

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

    NASA Astrophysics Data System (ADS)

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

    2017-06-01

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

  5. Control of vortex on a non-slender delta wing by a nanosecond pulse surface dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Zhao, Guang-yin; Li, Ying-hong; Liang, Hua; Han, Meng-hu; Hua, Wei-zhuo

    2015-01-01

    Wind tunnel experiments are conducted for improving the aerodynamic performance of delta wing using a leading-edge pulsed nanosecond dielectric barrier discharge (NS-DBD). The whole effects of pulsed NS-DBD on the aerodynamic performance of the delta wing are studied by balanced force measurements. Pressure measurements and particle image velocimetry (PIV) measurements are conducted to investigate the formation of leading-edge vortices affected by the pulsed NS-DBD, compared to completely stalled flow without actuation. Various pulsed actuation frequencies of the plasma actuator are examined with the freestream velocity up to 50 m/s. Stall has been delayed substantially and significant shifts in the aerodynamic forces can be achieved at the post-stall regions when the actuator works at the optimum reduced frequency of F + = 2. The upper surface pressure measurements show that the largest change of static pressure occurs at the forward part of the wing at the stall region. The time-averaged flow pattern obtained from the PIV measurement shows that flow reattachment is promoted with excitation, and a vortex flow pattern develops. The time-averaged locations of the secondary separation line and the center of the vortical region both move outboard with excitation.

  6. The Changes in Electrical and Interfacial Properties of Polyimide Exposed to Dielectric Barrier Discharge in SF6 Medium

    PubMed Central

    Alisoy, Hafiz Z.; Koseoglu, Murat

    2013-01-01

    The formation mechanism of space charges in polyimide (PI) which was exposed to dielectric barrier discharge (DBD) in SF6 medium and the effects of the space charges on interfacial and electrical properties of PI were investigated. The variation of normalized surface charge density on PI sample was calculated and illustrated for different DBD exposure times. The surface potential was measured to determine the effect of the space charges on the sample. Then, the contact angle values were measured to obtain the relation between the surface energy and the surface charge density. The expressions for the total charge and the concentration of trapped electrons were derived by using Poisson and continuity equations at stationary state. The space charges were determined experimentally by using thermally stimulated depolarization current (TSDC) method. Also, SEM image and FTIR spectrum of virgin and treated samples were presented to observe the structural variations. It was seen that the approach for the formation mechanism of the space charges agreed with the experimental data. However, it was concluded particularly for the short-time DBD treatments that the space charges accumulated in the sample should be considered besides the effects of surface functionalization in the determination of the surface energy. PMID:23844414

  7. Application of Dielectric-Barrier Discharge to the Stabilization of Lifted Non-Premixed Methane/Air Jet Flames

    NASA Astrophysics Data System (ADS)

    Liao, Ying-Hao; Zhao, Xiang-Hong

    2016-11-01

    Recent studies have shown that the application of non-thermal plasma is a promising way to enhance the flame stabilization and combustion efficiency. The present study experimentally investigates the effect of a dielectric-barrier discharge (DBD) on the stabilization of lifted non-premixed methane/air jet flames. The jet flame with co-annular DBD is produced by a co-flow burner and has a Reynolds number of Re = 2500, 5000, 7000, and 9000. The application of DBD is seen to have an impact on the flame lift-off height, and the degree of impact is subject to flow conditions (such as Reynolds number and co-flow velocity) and plasma power. In general, the enhancement of flame stabilization, indicated by the decrease in lift-off height, is most evident at low Reynolds number and co-flow velocity. For flames with a Reynolds number less than Re = 5000, flames are attached to the nozzle regardless of the co-flow velocity and plasma power; at Re = 5000, flames are often intermittently attached. The enhancement is not that significant at high Reynolds number and co-flow velocity at least for the plasma power employed in the current study. A slight increase in plasma power leads to enhanced flame stabilization.

  8. Nonthermal dielectric-barrier discharge plasma-induced inactivation involves oxidative DNA damage and membrane lipid peroxidation in Escherichia coli.

    PubMed

    Joshi, Suresh G; Cooper, Moogega; Yost, Adam; Paff, Michelle; Ercan, Utku K; Fridman, Gregory; Friedman, Gary; Fridman, Alexander; Brooks, Ari D

    2011-03-01

    Oxidative stress leads to membrane lipid peroxidation, which yields products causing variable degrees of detrimental oxidative modifications in cells. Reactive oxygen species (ROS) are the key regulators in this process and induce lipid peroxidation in Escherichia coli. Application of nonthermal (cold) plasma is increasingly used for inactivation of surface contaminants. Recently, we reported a successful application of nonthermal plasma, using a floating-electrode dielectric-barrier discharge (FE-DBD) technique for rapid inactivation of bacterial contaminants in normal atmospheric air (S. G. Joshi et al., Am. J. Infect. Control 38:293-301, 2010). In the present report, we demonstrate that FE-DBD plasma-mediated inactivation involves membrane lipid peroxidation in E. coli. Dose-dependent ROS, such as singlet oxygen and hydrogen peroxide-like species generated during plasma-induced oxidative stress, were responsible for membrane lipid peroxidation, and ROS scavengers, such as α-tocopherol (vitamin E), were able to significantly inhibit the extent of lipid peroxidation and oxidative DNA damage. These findings indicate that this is a major mechanism involved in FE-DBD plasma-mediated inactivation of bacteria.

  9. Numerical modelling of the effect of dry air traces in a helium parallel plate dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Lazarou, C.; Belmonte, T.; Chiper, A. S.; Georghiou, G. E.

    2016-10-01

    A validated numerical model developed for the study of helium barrier discharges in the presence of dry air impurities is presented in this paper. The model was used to numerically investigate the influence of air traces on the evolution of the helium dielectric barrier discharge (DBD). The level of dry air used as impurity was in the range from 0 to 1500 ppm, which corresponds to the most commonly encountered range in atmospheric pressure discharge experiments. The results presented in this study clearly show that the plasma chemistry and consequently the discharge evolution is highly affected by the concentration level of impurities in the mixture. In particular, it was observed that air traces assist the discharge ignition at low concentration levels (~55 ppm), while on the other hand, they increase the burning voltage at higher concentration levels (~1000 ppm). Furthermore, it was found that the discharge symmetry during the voltage cycle highly depends on the concentration of air. For the interpretation of the results, a detailed analysis of the processes that occur in the discharge gap is performed and the main reaction pathways of ion production are described. Thanks to this approach, useful insight into the physics behind the evolution of the discharge is obtained.

  10. Modeling and simulation of plasma gas flow driven by a single nanosecond-pulsed dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Xu, S. Y.; Cai, J. S.; Li, J.

    2016-10-01

    A simplified (7 species and 9 processes) plasma kinetic model is proposed to investigate the mechanism of the plasma aerodynamic actuation driven by nanosecond-pulsed dielectric barrier discharge (NS-DBD). The governing equations include conservation equations for each species, the Poisson equation for the electric potential, and Navier-Stokes equations for the gas dynamic flow. Numerical simulations of plasma discharge and flow actuation on NS-DBD plasma actuators have been carried out. Key discharge characteristics and the responses of the quiescent air were reproduced and compared to those obtained in experiments and numerical simulations. Results demonstrate that the reduced plasma kinetic model is able to capture the dominant species and reactions to predict the actuation in complicated hydrodynamics. For the one-dimensional planar and two-dimensional symmetric NS-DBD, the forming of the sheath collapse is mainly due to the charge accumulation and secondary emission from the grounded electrode. Rapid species number density rise and electric field drop occur at the edge of the plasma sheath, where the space charge density gradient peaks. For the aerodynamic actuation with typical asymmetry electrodes, discharge characteristics have a core area on the right edge of the upper electrode, where the value can be much higher. The formation and propagation of the compression waves generated through rapid heating have also been performed and compared to those measured in a recent experiment. Energy release leads to gas expansion and forms a cylindrical shock wave, centering at the upper electrode tip with low gas acceleration. For the present single pulsed 12 kV case, the mean temperature of gas heating reaches about 575 K at 1 μs and decreases to about 460 K at 10 μs.

  11. The simplest equivalent circuit of a pulsed dielectric barrier discharge and the determination of the gas gap charge transfer

    NASA Astrophysics Data System (ADS)

    Pipa, A. V.; Koskulics, J.; Brandenburg, R.; Hoder, T.

    2012-11-01

    The concept of the simplest equivalent circuit for a dielectric barrier discharge (DBD) is critically reviewed. It is shown that the approach is consistent with experimental data measured either in large-scale sinusoidal-voltage driven or miniature pulse-voltage driven DBDs. An expression for the charge transferred through the gas gap q(t) is obtained with an accurate account for the displacement current and the values of DBD reactor capacitance. This enables (i) the significant reduction of experimental error in the determination of q(t) in pulsed DBDs, (ii) the verification of the classical electrical theory of ozonizers about maximal transferred charge qmax, and (iii) the development of a graphical method for the determination of qmax from charge-voltage characteristics (Q-V plots, often referred as Lissajous figures) measured under pulsed excitation. The method of graphical presentation of qmax is demonstrated with an example of a Q-V plot measured under pulsed excitation. The relations between the discharge current jR(t), the transferred charge q(t), and the measurable parameters are presented in new forms, which enable the qualitative interpretation of the measured current and voltage waveforms without the knowledge about the value of the dielectric barrier capacitance Cd. Whereas for quantitative evaluation of electrical measurements, the accurate estimation of the Cd is important.

  12. Degradation of bisphenol-A by dielectric barrier discharge system: influence of polyethylene glycol stabilized nano zero valent iron particles

    NASA Astrophysics Data System (ADS)

    Tijani, Jimoh O.; Mouele, Massima E. S.; Fatoba, Ojo O.; Babajide, Omotola O.; Petrik, Leslie F.

    2017-09-01

    In this study we report the synthesis and catalytic properties of polyethylene glycol stabilized nano zero valent iron particles (PEG-nZVI) added to the dielectric barrier discharge (DBD) system to induce photo-Fenton process in the degradation of bisphenol A (BPA) in aqueous solution. The influence of operating parameters such as solution pH, initial concentration of the modelled pollutant and PEG-nZVI dosage on the extent of BPA degradation was investigated. The residual concentration of BPA and its intermediates were determined using high performance liquid chromatography (HPLC) and liquid chromatography mass spectrometry (LCMS). The high resolution scanning electron microscope (HRSEM), x-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area, and x-ray photoelectron spectroscopy (XPS) analysis confirmed the formation of filamentous, high surface area iron nanoparticles in the zero valent state. The BPA mineralization rate was monitored using total organic carbon (TOC) analyser. 100% BPA removal was achieved with DBD/PEG-nZVI system within 30 min compared to 67.9% (BPA) with DBD alone after 80 min. The complete BPA removal within a short reaction time was attributed to the existence of a synergetic effect in the combined DBD/PEG-nZVI system. Five new transformation products of BPA namely: 4-nitrophenol (C6H5NO3), 4-nitrosophenolate (C6H4NO2), 4-(prop-1-en-2-yl) cyclohexa-3,5-diene-1,2-dione, (C9H8O2), 4-(2-hydroxylpropan-2-yl)cyclohexane-3,5-diene-1,2-dione (C9H10O3), and 1,2-dimethyl-4-(2-nitropropan-2-yl)benzene (C9H10NO4) were identified. BPA degradation proceeded via ozonation, hydroxylation, dimerization, and decarboxylation and nitration step. The combined DBD/photo-Fenton-induced process was found to be the most efficient in the elimination of BPA in aqueous solutions and DBD alone.

  13. Deactivation of Escherichia coli in a post-discharge chamber coupled to an atmospheric pressure multi-electrode DBD plasma source

    NASA Astrophysics Data System (ADS)

    Pérez-Ruiz, V. H.; Peña-Eguiluz, R.; López-Callejas, R.; Mercado-Cabrera, A.; Muñoz-Castro, A. E.; Barocio, S. R.; Valencia-Alvarado, R.; de la Piedad Beneitez, A.; Rodríguez-Méndez, B. G.

    2012-06-01

    Experimental results from applying a room pressure RF multi-electrode DBD plasma source to the inhibition of the population growth of Gram negative Escherichia coli (E. coli) within a post-discharge reactor are reported. The sample to be treated is deposited in the post-discharge chamber at about 50 mm from the plasma source outlet. Thus, the active species generated by the source are conveyed toward the chamber by the working gas flow. The plasma characterization included the measurement of the axial temperature at different distances from the reactor outlet by means of a K-type thermocouple. The resulting 294 K to 322 K temperature interval corresponded to distances between 10 mm to 1 mm respectively. As the material under treatment is placed further away, any thermal damage of the sample by the plasma is prevented. The measurement and optimization of the ozone O3 concentration has also been carried out, provided that this is an active specie with particularly high germicide power. The effectiveness treatment of the E. coli bacteria growth inhibition by the proposed plasma source reached 99% when a 103 CFU/mL concentration on an agar plate had been exposed during ten minutes.

  14. Collection efficiency of submicrometre particles using single and double DBD in a wire-to-square tube ESP

    NASA Astrophysics Data System (ADS)

    Gouri, R.; Zouzou, N.; Tilmatine, A.; Moreau, E.; Dascalescu, L.

    2011-12-01

    The aim of this work is to study the collection of submicrometre particles charged by a dielectric barrier discharge (DBD) in two types of wire-to-square glass tube electrostatic precipitators (ESPs). They are, respectively, designated as single DBD-ESP and double DBD-ESP, depending on the absence or presence of a dielectric layer around the high-voltage wire electrode. The experiments are performed with incense smoke particles having a mean size of about 0.32 µm. An aerosol spectrometer is employed for characterizing the size distribution of these particles at the outlet of the ESPs. The collection efficiency is estimated for various applied voltages and frequencies (ranges: 8-28 kV, 0.3-1000 Hz) at a fixed air flow rate (5.1 L min-1). The electrical measurements show that in the case of the single DBD-ESP, the discharge mode is rather homogeneous. In contrast, the discharge has a filamentary behaviour in the case of the double DBD-ESP. Results show that the particle collection efficiency of both ESPs is higher at high applied voltages and within a certain frequency range. However, corroborating the collection efficiency results with the power consumption measurements reveals that the double DBD-ESP offers better performances for a larger frequency range.

  15. Effect of nitrogen addition to ozone generation characteristics by diffuse and filamentary dielectric barrier discharges at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Osawa, Naoki; Tsuji, Takafumi; Ogiso, Ryota; Yoshioka, Yoshio

    2017-05-01

    Ozone is widely used for gas treatment, advanced oxidation processes, microorganisms inactivation, etc. In this research, we investigated the effect of nitrogen addition to ozone generation characteristics by atmospheric pressure Townsend discharge (APTD) type and filamentary dielectric barrier discharge (DBD) type ozone generators. The result showed that the ozone generated by the filamentary DBD increases rapidly with the increase of O2 content, and is higher than that by the APTD. On the other hand, it is interesting that the ozone generated by the APTD gradually decreases with the increase of O2 content. In order to clarify why the characteristics of ozone generation by the two kinds of discharge modes showed different dependency to the N2 content, we analyzed the exhaust gas composition using FTIR spectroscopy and calculated the rate coefficients using BOLSIG+ code. As a result, we found that although O2 content decreased with increasing N2 content, additional O atoms produced by excited N2 molecules contribute to ozone generation in case of APTD. Contribution to the topical issue "The 15th International Symposium on High Pressure Low Temperature Plasma Chemistry (HAKONE XV)", edited by Nicolas Gherardi and Tomáš Hoder

  16. Decomposition of Potent Greenhouse Gases SF6, CF4 and SF5CF3 by Dielectric Barrier Discharge

    NASA Astrophysics Data System (ADS)

    Zhang, Renxi; Wang, Jingting; Cao, Xu; Hou, Huiqi

    2016-04-01

    For their distinguished global warming potential (GWP100) and long atmosphere lifespan, CF4, SF6 and SF5CF3 were significant in the field of greenhouse gas research. The details of discharging character and the optimal parameter were discussed by using a Dielectric Barrier Discharge (DBD) reactor to decompose these potent greenhouse gases in this work. The results showed that SF6 could be decomposed by 92% under the conditions of 5 min resident time and 3000 V applied voltage with the partial pressure of 2.0 kPa, 28.2 kPa, and 1.8 kPa for SF6, air and water vapor, respectively. 0.4 kPa CF4 could be decomposed by 98.2% for 4 min resident time with 30 kPa Ar added. The decomposition of SF5CF3 was much more effective than that of SF6 and CF4 and moreover, 1.3 kPa SF5CF3, discharged with 30 kPa O2, Ar and air, could not be detected when the resident time was 80 s, 40 s, and 120 s, respectively. All the results indicated that DBD was a feasible technique for the abatement of potent greenhouse gases. supported by National Natural Science Foundation of China (Nos. 20507004, 21577023)

  17. Measurement of the absolute CF2 concentration in a dielectric barrier discharge running in argon/fluorocarbon mixtures

    NASA Astrophysics Data System (ADS)

    Vinogradov, I. P.; Dinkelmann, A.; Lunk, A.

    2004-11-01

    The role of different CFx-radicals in plasma polymerization in fluorocarbon mixtures has not been determined yet. Therefore spectroscopic investigations of dielectric barrier discharges (DBDs) in argon/fluorocarbon mixtures at atmospheric pressure were conducted with the focus on measurement of the concentration of CFx-radicals. The following diagnostic procedures were applied: FTIR absorption spectroscopy to diagnose stable compounds in the discharge, optical emission spectroscopy of the DBD in the UV and visible range and measurement of the CF2 concentration by UV absorption spectroscopy. The DBD was running in argon with the following admixtures: CF4, C2F6, C2H2F4, C3F8, C3HF7, c-C4F8. The relative concentration of the CF3-radical and the absolute concentration of CF2 in Ar/fluorocarbon mixtures were measured by emission spectroscopy and by absorption and emission spectroscopy, respectively. Emission and absorption spectroscopy were performed simultaneously in combination with electrical measurements of the discharge characteristics. The influence of small amounts of hydrogen or oxygen added to the argon/fluorocarbon mixtures was investigated.

  18. 1D fluid model of the dielectric barrier discharge in chlorine

    NASA Astrophysics Data System (ADS)

    Avtaeva, Svetlana

    2016-09-01

    The 1D fluid model of the dielectric barrier discharge (DBD) in pure chlorine is developed. The discharge is excited in 8 mm gas gap between quartz dielectric layers of 2 mm thickness covered metallic electrodes. The source voltage US =U0 sin ωt with a frequency 100 kHz and amplitude 8 kV is applied to the electrodes. Chlorine pressure is varied from 15 to 100 Torr. At pressure of 15 Torr a breakdown appears with voltage drop across the discharge gap about 1 kV whereas at 100 Torr it appears with voltage drop about 2 kV. After the first current spike some lower current spikes are observes with chlorine pressure of 100 Torr and large in number current spikes of about identical magnitude are observed with the pressure of 15 Torr. The maximal current density at all pressures reaches about 4 mA/cm.2Total density of surface charge deposited on the electrodes during a half-cycle decreases with chlorine pressure because duration of the current spike discharge phase reduces with chlorine pressure. The average power density inputted in the discharge is 2.5-5.8 W/cm3 per a cycle. The Cl2 plasma is electronegative, the most abundant ions are Cl2+and Cl-. It is shown, that ions get about 95% of the discharge power as electrons get about 5% of the discharge power. 67-97% of the electron power is spending for dissociation and ionization of Cl2 molecules. Emission of Cl* atoms and Cl2*molecules is weak.

  19. Lab-scale test of a ventilation system including a dielectric barrier discharger and UV-photocatalyst filters for simultaneous removal of gaseous and particulate contaminants.

    PubMed

    Park, J H; Byeon, J H; Yoon, K Y; Hwang, J

    2008-02-01

    A ventilation system including a dielectric barrier discharger (DBD) and UV-photocatalyst (UVP) filters was designed and tested for simultaneous removal of gaseous and particulate contaminants in a test chamber. The DBD was used in the first stage of electrostatic precipitator (ESP) for particle charging and gas decomposition. An applied DC electric field was used in the second stage of ESP to collect the charged particles. UVP filters were then used to decompose gaseous species, such as formaldehyde (HCHO) and benzene, toluene, and xylene (BTX) including O3, which was inherently produced by the DBD. %Reductions in mass concentration of PM2.5 and number concentration of submicron particles were approximately 79.5% and 76.3%, respectively, after the ventilation with air cleaning system was operated for 5 h. Both HCHO and BTX were completely removed when the initial concentration of each gas was 1 ppm. Indoor air quality (IAQ) problems, such as sick building syndrome (SBS), are caused by limited ventilation in high-rise buildings. To overcome these problems, DBD and UVP filters were applied into a lab-scale ventilation system for simultaneous removal of pollutant particles and gases. The data supplied in this study will be useful for designing any actual ventilation system after further research, including scale-up experiments.

  20. Comparative simulation analysis on the ignition threshold of atmospheric He and Ar dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Yao, Congwei; Chang, Zhengshi; Chen, Sile; Ma, Hengchi; Mu, Haibao; Zhang, Guan-Jun

    2017-09-01

    Dielectric barrier discharge (DBD) is widely applied in many fields, and the discharge characteristics of insert gas have been the research focus for years. In this paper, fluid models of atmospheric Ar and He DBDs driven by 22 kHz sinusoidal voltage are built to analyze their ignition processes. The contributions of different electron sources in ignition process are analyzed, including the direct ionization of ground state atom, stepwise ionization of metastable particles, and secondary electron emission from dielectric wall, and they play different roles in different discharge stages. The Townsend direct ionization coefficient of He is higher than Ar with the same electrical field intensity, which is the direct reason for the different ignition thresholds between He and Ar. Further, the electron energy loss per free electron produced in Ar and He DBDs is discussed. It is found that the total electron energy loss rate of Ar is higher than He when the same electrical field is applied. The excitation reaction of Ar consumes the major electron energy but cannot produce free electrons effectively, which is the essential reason for the higher ignition threshold of Ar. The computation results of He and Ar extinction voltages can be explained in the view of electron energy loss, as well as the experimental results of different extinction voltages between Ar/NH3 and He DBDs.

  1. Computational Model of One-Dimensional Dielectric Barrier Discharges

    DTIC Science & Technology

    2005-06-01

    Siemens proposed a special electrical discharge to produce ozone (6:309). In 1955, Tanaka discovered that the DBD could be used for excimer...un t x t n nx t x tnn unn nu t n n n un u t nx t nx t x t n nx t x tunneNE ν δδϕ ϕ δ ν δ ν δϕ ϕϕ δδϕ ϕ ϕ . (91) This process is repeated for the...or blocks, consisting of the coefficients of the δ terms, nx is a four-term sub-vector of the unknown δ ’s and nb is a four-term sub- vector

  2. A Xenon dielectric barrier discharge lamp (172nm) with a fast-pulse voltage driver: Influence of the voltage waveform on plasma kinetic issues and light output.

    NASA Astrophysics Data System (ADS)

    Carman, Robert; Ward, Barry; Mildren, Richard; Kane, Deborah

    2003-10-01

    An important class of vacuum-ultraviolet (VUV) excimer lamps based on high pressure rare-gas and rare-gas halogen mixtures utilize the dielectric barrier discharge (DBD) to generate a transient, non-equilibrium plasma that yields high electrical to VUV conversion efficiency. Recent interest has focussed on the use of pulsed voltage excitation techniques (rather than conventional AC sinusoidal waveforms) to alter the physical appearance of the DBD "micro-discharges" from filamentary (AC) to semi-diffuse, conical or homogeneous (pulsed), whilst at the same time dramatically improving the lamp performance and VUV efficiency^1,2. We report results from a combined experimental/computer modelling study of a short-pulse excited co-axial DBD Xe lamp to investigate the influence of the pulsed voltage waveform on the discharge structure, lamp performance, VUV output, and electrical efficiency. The underlying plasma kinetics issues relating to lamp performance, including parasitic collisional processes that act to quench key xenon species population densities, are examined in detail. ^1 Vollkommer F and Hitzschke, US patent 5604410 (1997) ^2 R.P.Mildren and R.J.Carman, J.Phys.D, 34, L1-L6 (2001)

  3. Cathode fall measurement in a dielectric barrier discharge in helium

    SciTech Connect

    Hao, Yanpeng; Zheng, Bin; Liu, Yaoge

    2013-11-15

    A method based on the “zero-length voltage” extrapolation is proposed to measure cathode fall in a dielectric barrier discharge. Starting, stable, and discharge-maintaining voltages were measured to obtain the extrapolation zero-length voltage. Under our experimental conditions, the “zero-length voltage” gave a cathode fall of about 185 V. Based on the known thickness of the cathode fall region, the spatial distribution of the electric field strength in dielectric barrier discharge in atmospheric helium is determined. The strong cathode fall with a maximum field value of approximately 9.25 kV/cm was typical for the glow mode of the discharge.

  4. The different effects of oxygen and air DBD plasma byproducts on the degradation of methyl violet 5BN.

    PubMed

    Chen, Guangliang; Zhou, Mingyan; Chen, Shihua; Chen, Wenxing

    2009-12-30

    Through a novel design of the dielectric barrier discharge (DBD) plasma plume used in fabric-fiber surface modification, its discharge byproducts mainly including downstream gases and ultraviolet light were used to treat the dye solution. The different influence of oxygen and air DBD plasmas on the degradation of methyl violet 5BN (MV-5BN), which is widely used in textile industry, was investigated in this paper. The results showed that the cooperation between ultraviolet light and active species generated by the DBD plasma can decolorize MV-5BN effectively, and the chromophore peaks attributed to the -NN- bonds in MV-5BN molecule disappeared entirely when the azo dye solutions were treated for 25 min by the air and oxygen DBD plasmas. The degradation reaction followed an exponential kinetics over time, and the peak of aromatic derivatives at 209 nm in UV-vis spectra increased nearly 2.7 times when the dye solution was treated for 30 min by air DBD plasma. However, the oxygen DBD plasma could deplete the aromatic derivatives entirely. It is found that the formation of O(3) and NO(x) in the downstream gases of air and oxygen plasmas may be responsible for the different effects on the azo dye degradation.

  5. Natural laminar-turbulent transition delay by dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Ustinov, Maxim; Kogan, Mikhail; Litvinov, Vladimir; Uspensky, Alexander

    2011-12-01

    The use dielectric barrier discharge for the delay of laminar turbulent transition excited by natural flow disturbances in a quiet wind-tunnel was investigated experimentally. Optimal electrodes location and the operational regime of high-voltage impulse generator provided maximal downstream shift of transition location were found. It was demonstrated that the 10% increase of the laminar part of boundary layer can be obtained using barrier discharge with the cross-flow electrodes. This gives up to 20% friction drag reduction.

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

    NASA Astrophysics Data System (ADS)

    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.

  7. Collective Phenomena In Volume And Surface Barrier Discharges

    NASA Astrophysics Data System (ADS)

    Kogelschatz, U.

    2010-07-01

    Barrier discharges are increasingly used as a cost-effective means to produce non-equilibrium plasmas at atmospheric pressure. This way, copious amounts of electrons, ions, free radicals and excited species can be generated without appreciable gas heating. In most applications the barrier is made of dielectric material. In laboratory experiments also the use of resistive, ferroelectric and semiconducting materials has been investigated, also porous ceramic layers and dielectric barriers with controlled surface conductivity. 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 also devoted to biomedical applications and to plasma actuators for flow control. Sinu- soidal 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 laterally homogeneous discharges. Reviews of the subject and the older literature on barrier discharges were published by Kogelschatz (2002, 2003), by Wagner et al. (2003) and by Fridman et al. (2005). A detailed discussion of various properties of barrier discharges can also be found in the recent book "Non-Equilibrium Air Plasmas at Atmospheric Pressure" by Becker et al. (2005). The physical effects leading to collective phenomena in volume and surface barrier discharges will be discussed in detail. Special attention will be given to self-organization of current filaments. Main similarities and differences of the two types of barrier discharges will be elaborated.

  8. DBD plasma source operated in single-filamentary mode for therapeutic use in dermatology

    NASA Astrophysics Data System (ADS)

    Rajasekaran, Priyadarshini; Mertmann, Philipp; Bibinov, Nikita; Wandke, Dirk; Viöl, Wolfgang; Awakowicz, Peter

    2009-11-01

    Our dielectric barrier discharge (DBD) plasma source for bio-medical application comprises a copper electrode covered with ceramic. Objects of high capacitance such as the human body can be used as the opposite electrode. In this study, the DBD source is operated in single-filamentary mode using an aluminium spike as the opposite electrode, to imitate the conditions when the discharge is ignited on a raised point, such as hair, during therapeutic use on the human body. The single-filamentary discharge thus obtained is characterized using optical emission spectroscopy, numerical simulation, voltage-current measurements and microphotography. For characterization of the discharge, averaged plasma parameters such as electron distribution function and electron density are determined. Fluxes of nitric oxide (NO), ozone (O3) and photons reaching the treated surface are simulated. The calculated fluxes are finally compared with corresponding fluxes used in different bio-medical applications.

  9. Dynamic Characteristics of Positive Pulsed Dielectric Barrier Discharge for Ozone Generation in Air

    NASA Astrophysics Data System (ADS)

    Wei, Linsheng; Peng, Bangfa; Li, Ming; Zhang, Yafang; Hu, Zhaoji

    2016-02-01

    A comprehensive dynamic model consisting of 66 reactions and 24 species is developed to investigate the dynamic characteristics of ozone generation by positive pulsed dielectric barrier discharge (DBD) using parallel-plate reactor in air. The electron energy conservation equation is coupled to the electron continuity equation, the heavy species continuity equation, and Poisson's equation for a better description. The reliability of the model is experimentally confirmed. The model can be used to predict the temporal and spatial evolution of species, as well as streamer propagation. The simulation results show that electron density increases nearly exponentially in the direction to the anode at the electron avalanche. Streamer propagation velocity is about 5.26 × 104 m/s from anode to cathode in the simulated condition. The primary positive ion, negative ion, and excited species are O2+, O3- and O2(1Δg) in pulsed DBD in air, respectively. N2O has the largest density among nitrogen oxides. e and N2+ densities in the streamer head increase gradually to maximum values with the development of the streamer. Meanwhile, the O2+, O, O3, N2(A3Σ) and N2O densities reach maximum values in the vicinity of the anode. supported by National Natural Science Foundation of China (Nos. 51366012 and 11105067), Jiangxi Province Young Scientists (Jinggang Star) Cultivation Plan of China (No. 20133BCB23008), Natural Science Foundation of Jiangxi, China (No. 20151BAB206047) and Jiangxi Province Higher School Science and Technology Landing Plan of China (No. KJLD-14015)

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

    NASA Astrophysics Data System (ADS)

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

    2017-07-01

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

  11. Dielectric barrier discharge molecular emission spectrometer as multichannel GC detector for halohydrocarbons.

    PubMed

    Li, Wei; Zheng, Chengbin; Fan, Guangyu; Tang, Li; Xu, Kailai; Lv, Yi; Hou, Xiandeng

    2011-07-01

    A novel microplasma molecular emission spectrometer based on an atmospheric pressure dielectric barrier discharge (DBD) is described and further used as a promising multichannel GC detector for halohydrocarbons. The plasma is generated in a DBD device consisting of an outer electrode (1.2 mm in diameter) and an inner electrode (1.7 mm in diameter) within a small quartz tube (3.0 mm i.d. × 5.0 mm o.d. × 50 mm), wherein analyte molecules are excited by the microplasma to generate molecular emission. Therefore, the analytes are selectively and simultaneously detected with a portable charge-coupled device (CCD) via multichannel detection of their specific emission lines. The performance of this method was evaluated by separation and detection of a model mixture of chlorinated hydrocarbons (CHCl(3) and CCl(4)), brominated hydrocarbons (CH(2)Br(2) and CH(2)BrCH(2)Br), and iodinated hydrocarbons (CH(3)I and (CH(3))(2)CHI) undergoing GC with the new detector. The completely resolved identification of the tested compounds was achieved by taking advantages of both chromatographic and spectral resolution. Under the optimized conditions with the CCD spectrometer set at 258, 292, and 342 nm channels for determination of chlorinated hydrocarbons, brominated hydrocarbons, and iodinated hydrocarbons, respectively, this detector with direct injection provided detection limits of 0.07, 0.06, 0.3, 0.04, 0.05, and 0.02 μg mL(-1) for CCl(4), CHCl(3), CH(2)Cl(2), CH(3)I, CH(3)CH(2)I, and (CH(3))(2)CHI, respectively.

  12. Adaptive flow control of low-Reynolds number aerodynamics using dielectric barrier discharge actuator

    NASA Astrophysics Data System (ADS)

    Cho, Young-Chang; Shyy, Wei

    2011-10-01

    Aerodynamic performance of low-Reynolds number flyers, for a chord-based Reynolds number of 10 5 or below, is sensitive to wind gusts and flow separation. Active flow control offers insight into fluid physics as well as possible improvements in vehicle performance. While facilitating flow control by introducing feedback control and fluidic devices, major challenges of achieving a target aerodynamic performance under unsteady flow conditions lie on the high-dimensional nonlinear dynamics of the flow system. Therefore, a successful flow control framework requires a viable as well as accessible control scheme and understanding of underlying flow dynamics as key information of the flow system. On the other hand, promising devices have been developed recently to facilitate flow control in this flow regime. The dielectric barrier discharge (DBD) actuator is such an example; it does not have moving parts and provides fast impact on the flow field locally. In this paper, recent feedback flow control studies, especially those focusing on unsteady low-Reynolds number aerodynamics, are reviewed. As an example of an effective flow control framework, it is demonstrated that aerodynamic lift of a high angle-of-attack wing under fluctuating free-stream conditions can be stabilized using the DBD actuator and an adaptive algorithm based on general input-output models. System nonlinearities and control challenges are discussed by assessing control performance and the variation of the system parameters under various flow and actuation conditions. Other fundamental issues from the flow dynamics view point, such as the lift stabilization mechanism and the influence on drag fluctuation are also explored. Both potentiality and limitation of the linear modeling approach are discussed. In addition, guidelines on system identification and the controller and actuator setups are suggested.

  13. Flow control around a circular cylinder using pulsed dielectric barrier discharge surface plasma

    SciTech Connect

    Jukes, Timothy N.; Choi, Kwing-So

    2009-08-15

    Dielectric barrier discharge (DBD) plasma actuators have been used to control the flow around a circular cylinder at Re=15 000, where the near-wake structure was studied using time-resolved particle image velocimetry with simultaneous measurements of the dynamic lift and drag forces. It was shown that the vortex shedding was suppressed when the surface plasma placed near the natural separation point was activated in a pulsed mode at nondimensional frequency, f{sub p}{sup +}, above 0.6 with a force coefficient, C{sub p}, greater than 0.05%. Plasma actuator performance on flow control was summarized by mapping the changes in drag and lift fluctuations as a function of the forcing frequency and the force coefficient. They showed that more than 70% reduction in lift fluctuations was obtained with up to 32% drag reduction at f{sub p}{sup +}=2.0 and C{sub p}=0.32%. Here, narrowing of the wake was observed as the plasma promoted shear-layer roll-ups at the forcing frequency. This, however, did not affect the shear layer on the opposite side of the wake. At nondimensional forcing frequencies less than 0.6, the vortex shedding locked onto a multiple of the plasma frequency to amplify the wake oscillations. This caused more than 85% increase in lift fluctuations with 8% drag increase at f{sub p}{sup +}=0.2 and C{sub p}=0.01%. The efficiency of flow control using DBD plasma was found to be 1%-2% for drag reduction while around 6% for drag increase.

  14. A Simplified Numerical Study of the Kr/Cl2 Plasma Chemistry in Dielectric Barrier Discharge

    NASA Astrophysics Data System (ADS)

    N. Larbi Daho, Bachir; Belasri, A.

    2013-04-01

    In this paper, the generation of excimers and exciplexe radiation in mixtures of rare gas with halogen by homogeneous dielectric barrier discharge (DBD) is investigated. The typical characteristics of an excilamp based on KrCl* exciplexe molecules and the kinetic processes for the formation and the decay of this molecules in the Kr/Cl2 mixture are studied. The computer model developed is based on the Kr/Cl2 mixture chemistry, the equivalent electric circuit and the Boltzmann equations. The importance in the kinetic processes of some species such as the metastable state of Krypton (Kr*(3P0,2)) and the negative ion of chloride (Cl-) is considered. The results illustrate the time variations of charged species (ne, Kr+, Cl-, Cl+, Cl+2, Kr+2), excited atoms and molecules (Kr*(3P0,2), Kr*(3P1), Cl*, Cl*2), the excimers (Kr*2, KrCl*(B), KrCl*(C), Kr2Cl*) and the UV photon concentrations (in 222 nm, 235 nm, 258 nm and 325 nm range). The effects of chlorine concentration and the total gas pressure in the Kr-Cl2 discharge on the electric parameters and radiation emissions are investigated.

  15. High-pressure dielectric barrier discharge Xenon lamps generating short pulses of high-peak-power VUV radiation (172nm) with high pulse-to-pulse reproducibility.

    NASA Astrophysics Data System (ADS)

    Carman, Robert; Ward, Barry; Mildren, Richard; Kane, Deborah

    2003-10-01

    Dielectric barrier discharges (DBDs) are used to efficiently generate radiation in the ultraviolet and vacuum-ultraviolet spectral regions (88nm-350nm) by forming rare-gas and rare-gas halide excimers in a transient plasma. Usually, DBD lamps generate the light output quasi-continuously or in bursts with a high degree of stochastic or random variability in the instantaneous UV/VUV intensity. However, regular pulses of high-peak-power UV/VUV, with high pulse-to-pulse reproducibility, are of interest for applications in biology, surface treatment and cleaning, and time-resolved fluorescence spectroscopy. Such pulses can be generated from spatially homogeneous plasmas in a Xe DBD when the discharge is driven by uni-polar voltage pulses of short duration ( 100ns)^1. In the present study, we will report Xe DBD lamp performance and VUV output pulse characteristics for gas pressures up to 2.5bar and excitation conditions tailored for high-peak-power output. The experimental results will be compared to theoretical results from a detailed 1-D computer model of the spatio-temporal evolution of the plasma kinetics and Xe species population densities. ^1R.P.Mildren and R.J.Carman, J.Phys.D, 34, L1-L6, (2001)

  16. Treatment surfaces with atomic oxygen excited in dielectric barrier discharge plasma of O{sub 2} admixed to N{sub 2}

    SciTech Connect

    Shun'ko, E. V.; Belkin, V. S.

    2012-06-15

    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 N{sub 2} and O{sub 2}, 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 2s{sup 2}2p{sup 4}({sup 1}S{sub 0}) 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.

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

    NASA Astrophysics Data System (ADS)

    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)

  18. Experimental Research on the Sterilization of Escherichia Coli and Bacillus Subtilis in Drinking Water by Dielectric Barrier Discharge

    NASA Astrophysics Data System (ADS)

    Li, Yang; Yi, Chengwu; Li, Jingjing; Yi, Rongjie; Wang, Huijuan

    2016-02-01

    The bactericidal effect on the representative type of Gram-negative Escherichia coli (E. coli) and Gram-positive Bacillus subtilis in drinking water was investigated in this paper by using dielectric barrier discharge (DBD) advanced oxidation technology. The sterilizing rates under different conditions of reaction time t, input voltage V, pH value, and initial concentration of bacteria C0 were investigated to figure out the optimum sterilization conditions. Our observations and comparisons of cell morphology alteration by scanning electron microscopy and transmission electron microscopy revealed the sterilization mechanisms. The results showed that the sterilizing rate increased obviously with the extension of reaction time t and the rise of input voltage V. The optimal sterilization effect was achieved when the pH value was 7.1. As the initial concentration of bacteria rose, the sterilizing rate decreased. When the input voltage was 2.2 kV and the initial concentration of bacteria was relatively low, the sterilizing rate almost reached 100% after a certain treatment time in neutral aqueous solution. The reasons for the great damage of cell structure and the killing of bacteria are the oxidation of O3, OH and the accumulation of active species produced by DBD. The article provides a certain theoretical and experimental basis for DBD application in water pollution treatment. supported by the Science and Technology Support Project Plan and Social Development of Jiangsu Province, China (No. BE2011732), the Science and Technology Support Project Plan and Social Development of Zhenjiang, Jiangsu Province, China (No. SH2012013)

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

    SciTech Connect

    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.

  20. Effects of surface modification by atmospheric oxygen dielectric barrier discharge plasma on PBO fibers and its composites

    NASA Astrophysics Data System (ADS)

    Liu, Zhe; Chen, Ping; Zhang, Xiaoliang; Yu, Qi; Ma, Keming; Ding, Zhenfeng

    2013-10-01

    In this paper, oxygen dielectric barrier discharge (oxy-DBD) plasma was employed to modify PBO fibers and enhance the interfacial adhesion of PBO fiber/bismaleimide composites. The interlaminar shear strength (ILSS) of the composites was improved greatly to 62.0 MPa with an increment of 41.2% at 30 W/cm3, 24 s. The SEM images of fracture morphology indicated that the failure place shifted from the interface to the matrix, and the water absorption decreased from 1.96 to 1.53%, the two results demonstrated the improved adhesive strength in other ways. In addition, the ILSS retention ratio of PBO/BMI composites after boiling in water were about 90%, confirming good humid resistance of the composites. The results obtained from XPS and AFM revealed that some polar groups were introduced onto PBO fibers and the surface morphology of PBO fibers was roughened. As a result, the wettability, reactivity and roughness of PBO fibers were all improved, they contributed to the improvement of the ILSS of the composites. The comparisons with air-DBD plasma showed that the chemical changes of PBO fibers were not alike because of different plasma gases.

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

    NASA Astrophysics Data System (ADS)

    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.

  2. Optical visualization and electrical characterization of fast-rising pulsed dielectric barrier discharge for airflow control applications

    NASA Astrophysics Data System (ADS)

    Benard, Nicolas; Zouzou, Nourredine; Claverie, Alain; Sotton, Julien; Moreau, Eric

    2012-02-01

    Flow control consists of manipulating flows in an effective and robust manner to improve the global performances of transport systems or industrial processes. Plasma technologies, and particularly surface dielectric barrier discharge (DBD), can be a good candidate for such purpose. The present experimental study focuses on optical and electrical characterization of plasma sheet formed by applying a pulse of voltage with rising and falling periods of 50 ns for a typical surface DBD geometry. Positive and negative polarities are compared in terms of current behavior, deposited energy, fast-imaging of the plasma propagation, and resulting modifications of the surrounding medium by using shadowgraphy acquisitions. Positive and negative pulses of voltage produce streamers and corona type plasma, respectively. Both of them result in the production of a localized pressure wave propagating in the air with a speed maintained at 343 m/s (measurements at room temperature of 20 °C). This suggests that the produced pressure wave can be considered as a propagating sound wave. The intensity of the pressure wave is directly connected to the dissipated energy at the dielectric wall with a linear increase with the applied voltage amplitude and a strong dependence toward the rising time. At constant voltage amplitude, the pressure wave is reinforced by using a positive pulse. The present investigation also reveals that rising and decaying periods of a single pulse of voltage result in two distinct pressure waves. As a result, superposition or successive pressure wave can be produced by adjusting the width of the pulse.

  3. Synthesis of flat sticky hydrophobic carbon diamond-like films using atmospheric pressure Ar/CH4 dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Rincón, R.; Hendaoui, A.; de Matos, J.; Chaker, M.

    2016-06-01

    An Ar/CH4 atmospheric pressure dielectric barrier discharge (AP-DBD) was used to synthesize sticky hydrophobic diamond-like carbon (DLC) films on glass surface. The film is formed with plasma treatment duration shorter than 30 s, and water contact angles larger than 90° together with contact angle hysteresis larger than 10° can be achieved. According to Fourier transform infrared spectroscopy and atomic force microscopy analysis, hydrocarbon functional groups are created on the glass substrate, producing coatings with low surface energy (˜35 mJ m-2) with no modification of the surface roughness. To infer the plasma processes leading to the formation of low energy DLC surfaces, optical emission spectroscopy was used. From the results, a direct relationship between the CH species present in the plasma and the carbon concentration in the hydrophobic layer was found, which suggests that the CH species are the precursors of DLC film growth. Additionally, the plasma gas temperature was measured to be below 350 K which highlights the suitability of using AP-DBD to treat thermo-sensitive surfaces.

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

    PubMed Central

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

    2015-01-01

    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. PMID:26656857

  5. Removal of H₂S in a novel dielectric barrier discharge reactor with photocatalytic electrode and activated carbon fiber.

    PubMed

    Chen, Jie; Xie, Zhenmiao

    2013-10-15

    A novel dielectric barrier discharge (DBD) reactor was applied for removal of H2S. Activated carbon fiber (ACF) and a photocatalytic electrode prepared from sintered metal fibers (SMF) were introduced into the novel reactor. H2S removal rate was enhanced dramatically due to the synergism between DBD and ACF. Peak voltage, initial concentration, resident time and humidity were important factors that influenced the H2S removal rate. 75 mg/m(3) H2S removal rate reached 99.9% at a peak voltage of 25 kV and with a resident time of 2s in the novel reactor. Humidity had an inhibition to H2S decomposition at low peak voltages. And the inhibition became slight at high peak voltages (>20 kV). The novel reactor exhibited better by-products (SO2 and O3) control than other reactors did. And it also had excellent performance stabilization in a long-term operation (30 d).

  6. Optical emission characteristics of medium- to high-pressure N{sub 2} dielectric barrier discharge plasmas during surface modification of polymers

    SciTech Connect

    Liu Dongping; Niu Jinhai; Yu Naisen

    2011-11-15

    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 N{sub 2} (C{sup 3}{Pi}{sub u}) state in the generated plasmas. The authors generated the N{sub 2} DBD plasmas at a driving frequency of 1-7 kHz and a discharge pressure of 20-10{sup 5} Pa for the surface modification of a polyethylene terephthalate (PET) sample. It was found that the vibrational temperature was greatly affected by the N{sub 2} pressure while the rotational temperature remained constant in the N{sub 2} pressure range of 20-10{sup 5} Pa. The emission intensity of N{sub 2} first positive system (B{sup 3}{Pi}{yields}A{sup 3}{Sigma}) rapidly decreased at an increasing N{sub 2} pressure due to the collisional relaxation process of the B{sup 3}{Pi} state with N{sub 2} molecules. The N{sub 2}{sup +}(B{sup 2}{Sigma}{sub u}{sup +}{yields}X{sup 2}{Sigma}{sub g}{sup +}) radiative transition was observed in the low-pressure DBD plasmas, which was attributed to the direct electron impact ionization of N{sub 2} molecules. The surface characterizations of treated PET samples by contact angle measurement and atomic force microscopy indicate that the low-pressure N{sub 2} 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 N{sub 2} pressure, which turn to determine the surface properties of treated PET samples.

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

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

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

  8. [Influence of pressure on plasma temperature in air/argon dielecteic barrier discharge].

    PubMed

    Dong, Li-Fang; Qi, Yu-Yan; Li, Li-Chun; Hao, Ya-Juan; Gao, Rui-Ling; Zhao, Zeng-Chao; Li, Xue-Chen

    2008-01-01

    Electron excitation temperature and molecule vibrational temperature in argon/air dielectric barrier discharge (DBD) at different gas pressure with water electrodes were studied by using optical emission spectra. The spectral lines of Ar I 763. 51 nm(2P6 --> 1S5) and Ar I 772.42 nm(2P2 --> 1S3) were chosen to calculate electron excitation temperature by the relative intensity ratio method. The emission spectra of nitrogen band of second positive system ( C3 pi(u) --> B3 pi(g)) were measured at the same time. The molecule vibration temperature was estimated by the emission intensities of different bands with delta(nu) = -1, delta(nu) = -2, and delta(nU) = -3 in nitrogen band of second positive system, using Boltzmann's plot method. In addition, the relative line intensities of nitrogen (0-0) band of first negative system at 391.4 nm and (0-0) band of second positive system at 337.1 nm were also measured to study the variation of electron energy. It was found that the electron excitation temperature decreased from 4 700 to 3 300 K and the molecule vibrational temperature decreased from 3 200 to 2 900 K with increasing gas pressure from 20 to 60 kPa. Besides, the ratio of I(N2+)/I(N2) also decreased with pressure increasing from 20 to 60 kPa, indicating that the average electron energy decreases with the gas pressure increasing. These results are of great importance to the study of plasma dynamics of dielectric barrier discharge and also to the underlying industrial applications.

  9. Interaction of atomized colloid with an ac electric field in a dielectric barrier discharge reactor used for deposition of nanocomposite coatings

    NASA Astrophysics Data System (ADS)

    Profili, Jacopo; Dap, Simon; Levasseur, Olivier; Naude, Nicolas; Belinger, Antoine; Stafford, Luc; Gherardi, Nicolas

    2017-02-01

    Nanocomposite thin films can be obtained by polymerization of a colloidal solution in a dielectric barrier discharge (DBD) at atmospheric pressure. In such a process, the dispersion of nanoparticles into the matrix is driven by the charging, transport, and deposition dynamics of the atomized colloid. This work examines the interaction of atomized TiO2 nanoparticles with ac electric fields in a plane-to-plane dielectric barrier discharge reactor. Experiments are performed with the discharge off to examine transport and deposition phenomena over a wide range of experimental conditions with a fixed particle charge distribution. Scanning electron microscopy reveals that the size distribution of TiO2 nanoparticles collected at different locations along the substrate surface placed on the bottom electrode of the DBD reactor can judiciously be controlled by varying the amplitude and frequency of the ac electric field. These results are also compared to the predictions of a simple particle motion model accounting for the electrostatic force, the gravitational force, and the neutral drag force in the laminar flow. It is found that while the initial charge distribution of atomized particles strongly influences the total deposition yield, its maximal position on the substrate, and the width of the deposited area, the initial size distribution of the particles at the entrance of the reactor mostly changes the size distribution at each position along the substrate surface.

  10. Characterization of DBD Plasma Actuators Performance Without External Flow - Part I: Thrust-Voltage Quadratic Relationship in Logarithmic Space for Sinusoidal Excitation

    NASA Technical Reports Server (NTRS)

    Ashpis, David E.; Laun, Matthew C.

    2016-01-01

    Results of characterization of Dielectric Barrier Discharge (DBD) plasma actuators without external flow are presented. The results include aerodynamic and electric performance of the actuators without external flow for different geometrical parameters, dielectric materials and applied voltage level and wave form.

  11. Hybrid catalytic-DBD plasma reactor for the production of hydrogen and preferential CO oxidation (CO-PROX) at reduced temperatures.

    PubMed

    Rico, Víctor J; Hueso, José L; Cotrino, José; Gallardo, Victoria; Sarmiento, Belén; Brey, Javier J; González-Elipe, Agustín R

    2009-11-07

    Dielectric Barrier Discharges (DBD) operated at atmospheric pressure and working at reduced temperatures (T < 115 degrees C) and a copper-manganese oxide catalyst are combined for the direct decomposition and the steam reforming of methanol (SRM) for hydrogen production and for the preferential oxidation of CO (CO-PROX).

  12. Effects of hydrocarbon contamination on ozone generation with dielectric barrier discharges

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2006-10-01

    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 (DBD) is performed with and without porous material containing TiO2. The metallic inner electrode is in contact with the gas gap. 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. For the same injected energy 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) [1]. 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 to 70% of the injected energy depending on the presence of the photocatalytic material.They are attributed to desorption of charges triggered by light emitted by a first filament. The influence of 900 ppm of C2H2 as well as external ultraviolet irradiation on the CADF is also reported. [1] O. Guaitella, F. Thevenet, C. Guillard, A. Rousseau J. Phys. D : appl. Phys (2006) accepted.

  14. Atomic oxygen characteristics in a dielectric barrier discharge developed for wound treatment

    NASA Astrophysics Data System (ADS)

    Baldus, Sabrina; Schroeder, Daniel; Schulz-von der Gathen, Volker; Bibinov, Nikita; Awakowicz, Peter

    2014-10-01

    Nowadays, infected chronic wounds are a major problem of society. Atmospheric pressure plasmas like dielectric barrier discharges (DBDs) have already shown their ability of improving the wound healing process of chronic wounds in clinical trials. Yet, the mechanism of action is poorly understood. A DBD comprising a single driven electrode is a beneficial configuration for wound treatment. The patient itself functions as the counter electrode. Hence, reactive oxygen species (ROS) like ozone or atomic oxygen produced in the plasma reach the wound directly. Some ROS, including superoxide or nitric oxide, are produced by skin cells to repulse invading bacteria. Nevertheless, a very high amount of ROS leads to oxidative stress and can cause cell damage or even cell death. Therefore it is crucial to have a well characterized plasma for effective wound treatment. Plasma parameters are determined using absolutely calibrated optical emission spectroscopy. Density of atomic oxygen is measured applying xenon-calibrated two photon absorption laser induced fluorescence spectroscopy. A simulation of the afterglow chemistry, developed to gain insight in the characteristics of the atomic oxygen and its flux towards the treated surface, is cross-checked with measurement results. Work supported by the German Research Foundation within PAK816.

  15. Spectroscopic Study of Plasma Polymerized a-C:H Films Deposited by a Dielectric Barrier Discharge

    PubMed Central

    Chandrashekaraiah, Thejaswini Halethimmanahally; Bogdanowicz, Robert; Rühl, Eckart; Danilov, Vladimir; Meichsner, Jürgen; Thierbach, Steffen; Hippler, Rainer

    2016-01-01

    Plasma polymerized a-C:H thin films have been deposited on Si (100) and aluminum coated glass substrates by a dielectric barrier discharge (DBD) operated at medium pressure using C2Hm/Ar (m = 2, 4, 6) gas mixtures. The deposited films were characterized by Fourier transform infrared reflection absorption spectroscopy (FT-IRRAS), Raman spectroscopy, and ellipsometry. FT-IRRAS revealed the presence of sp3 and sp2 C–H stretching and C–H bending vibrations of bonds in the films. The presence of D and G bands was confirmed by Raman spectroscopy. Thin films obtained from C2H4/Ar and C2H6/Ar gas mixtures have ID/IG ratios of 0.45 and 0.3, respectively. The refractive indices were 2.8 and 3.1 for C2H4/Ar and C2H6/Ar films, respectively, at a photon energy of 2 eV. PMID:28773715

  16. Abatement of toluene from gas streams via ferro-electric packed bed dielectric barrier discharge plasma.

    PubMed

    Liang, Wenjun; Li, Jian; Li, Jie; Jin, Yuquan

    2009-10-30

    Destruction of gaseous toluene via 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 three kinds of reactors was compared in terms of specific energy density (SED), energy yield (EY), toluene decomposition. In order to optimize the geometry of the reactor, the removal efficiency of toluene was compared for various inner electrode diameters. In addition, qualitative analysis on by-products and particular discussion on toluene abatement mechanisms were also presented. It has been found that ferro-electric packed bed DBD reactor could effectively decompose toluene. Toluene removal efficiency enhanced with increasing SED. With respect to toluene conversion, 1.62 mm electrode appeared to be superior to 1.06 mm electrodes. BaTiO3 reactor had the highest toluene removal efficiency among the reactors. For NaNO2 reactor, the highest EY could reach 17.0 mg/kWh to a certain extent.

  17. Effect of atmospheric pressure dielectric barrier discharge plasma on the biological activity of naringin.

    PubMed

    Kim, Hyun-Joo; Yong, Hae In; Park, Sanghoo; Kim, Kijung; Kim, Tae Hoon; Choe, Wonho; Jo, Cheorun

    2014-10-01

    The biological activity of naringin treated with atmospheric pressure plasma was evaluated to investigate whether exposure to plasma can be used as a method to improve the biological activity of natural materials. Naringin was dissolved in methanol (at 500 ppm) and transferred to a container. A dielectric barrier discharge (DBD) (250 W, 15 kHz, ambient air) was then generated. Treatment with the plasma for 20 min increased the radical-scavenging activity, FRAP value, and the total phenolic compound content of naringin from 1.45% to 38.20%, from 27.78 to 207.78 μM/g, and from 172.50 to 225.83 ppm, respectively. Moreover, the tyrosinase-inhibition effect of naringin increased from 6.12% to 83.30% upon plasma treatment. Naringin treated with plasma exhibited antimicrobial activity against foodborne pathogens, especially Salmonella Typhimurium; an activity that was absent before plasma treatment. Structural modifications induced in the naringin molecule by plasma might be responsible for improving the biological activity of naringin.

  18. Unmanned air vehicle flow separation control using dielectric barrier discharge plasma at high wind speed

    NASA Astrophysics Data System (ADS)

    Zhang, Xin; Huang, Yong; Wang, WanBo; Wang, XunNian; Li, HuaXing

    2014-06-01

    The present paper described an experimental investigation of separation control of an Unmanned Aerial Vehicle (UAV) at high wind speeds. The plasma actuator was based on Dielectric Barrier Discharge (DBD) and operated in a steady manner. The flow over a wing of UAV was performed with smoke flow visualization in the ϕ0.75 m low speed wind tunnel to reveal the flow structure over the wing so that the locations of plasma actuators could be optimized. A full model of the UAV was experimentally investigated in the ϕ3.2 m low speed wind tunnel using a six-component internal strain gauge balance. The effects of the key parameters, including the locations of the plasma actuators, the applied voltage amplitude and the operating frequency, were obtained. The whole test model was made of aluminium and acted as a cathode of the actuator. The results showed that the plasma acting on the surface of UAV could obviously suppress the boundary layer separation and reduce the model vibration at the high wind speeds. It was found that the maximum lift coefficient of the UAV was increased by 2.5% and the lift/drag ratio was increased by about 80% at the wind speed of 100 m/s. The control mechanism of the plasma actuator at the test configuration was also analyzed.

  19. Application of the dielectric barrier discharge to detect defects in a teflon coated metal surface

    NASA Astrophysics Data System (ADS)

    Ebihara, Kenji; Tanaka, Takahiro; Ikegami, Tomoaki; Yamagata, Yukihiko; Matsunaga, Toru; Yamashita, Kazutaka; Oyama, Yoshifumi

    2003-12-01

    In the semiconductor industry, flexible stainless steel tubes, the inside of which are coated with thick Teflon films, by the splay coating method, have been used to prevent their degradation and erosion by organic solvents. We have developed an inspection system to detect pinholes and cracks in the deposited Teflon films, and the dielectric barrier discharge (DBD) was employed to reduce residual substances and damages to the coated film in the tube. Conducting water contained in the cylinder-like glass pipe was used as a liquid electrode to apply a high voltage at any portion of the tube tested. A defective part with a pinhole was modelled by a point electrode in this experiment, because the uncoated defective part has a lower electric breakdown voltage. High frequency voltage (10 kHz) was applied between the point electrode and the liquid electrode. The level of the liquid electrode was varied to detect the occurrence of a microdischarge. It is found that the number of current pulses due to the microdischarge can be used to estimate the size and location of the defective uncoated point of the sample tube.

  20. EHD-driven mass transport enhancement in surface dielectric barrier discharges

    NASA Astrophysics Data System (ADS)

    Taglioli, M.; Shaw, A.; Wright, A.; FitzPatrick, B.; Neretti, G.; Seri, P.; Borghi, C. A.; Iza, F.

    2016-12-01

    Surface dielectric barrier discharges (S-DBDs) have received renewed attention in recent years for their potential application in emerging biomedical, environmental and agricultural applications. In most of these applications, the plasma is not in direct contact with the substrate being treated and the transport of reactive species from the plasma to the substrate is typically assumed to be controlled by diffusion. Here, we demonstrate that generally this is not the case and that electrohydrodynamic (EHD) forces can produce jets that enhance the delivery of these species, thereby influencing the efficacy of the S-DBD device. In particular, we have studied the degradation of potassium indigotrisulfonate solutions exposed to S-DBDs generated in devices with annular electrodes of diameters varying between 10 mm and 50 mm. All the devices were driven at constant linear power density (watts per cm of plasma length) and although local plasma properties remained the same in all the devices, a three-fold efficacy enhancement was observed for devices of diameter ~30 mm due to EHD effects.

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

    NASA Astrophysics Data System (ADS)

    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)

  2. Low-pressure barrier discharge ion source using air as a carrier gas and its application to the analysis of drugs and explosives.

    PubMed

    Usmanov, Dilshadbek T; Yu, Zhan; Chen, Lee Chuin; Hiraoka, Kenzo; Yamabe, Shinichi

    2016-02-01

    In this work, a low-pressure air dielectric-barrier discharge (DBD) ion source using a capillary with the inner diameter of 0.115 and 12 mm long applicable to miniaturized mass spectrometers was developed. The analytes, trinitrotoluene (TNT), 1,3,5-trinitroperhydro-1,3,5-triazine (RDX), 1,3,5,7-tetranitroperhydro-1,3,5,7-tetrazocine (HMX), pentaerythritol tetranitrate (PETN), nitroglycerine (NG), hexamethylene triperoxide diamine (HMTD), caffeine, cocaine and morphine, introduced through the capillary, were ionized by a low-pressure air DBD. The ion source pressures were changed by using various sizes of the ion sampling orifice. The signal intensities of those analytes showed marked pressure dependence. TNT was detected with higher sensitivity at lower pressure but vice versa for other analytes. For all analytes, a marked signal enhancement was observed when a grounded cylindrical mesh electrode was installed in the DBD ion source. Among nine analytes, RDX, HMX, NG and PETN could be detected as cluster ions [analyte + NO3 ](-) even at low pressure and high temperature up to 180 °C. The detection indicates that these cluster ions are stable enough to survive under present experimental conditions. The unexpectedly high stabilities of these cluster ions were verified by density functional theory calculation. Copyright © 2016 John Wiley & Sons, Ltd.

  3. Flexible thin-layer dielectric barrier discharge plasma treatment of pork butt and beef loin: effects on pathogen inactivation and meat-quality attributes.

    PubMed

    Jayasena, Dinesh D; Kim, Hyun Joo; Yong, Hae In; Park, Sanghoo; Kim, Kijung; Choe, Wonho; Jo, Cheorun

    2015-04-01

    The effects of a flexible thin-layer dielectric barrier discharge (DBD) plasma system using a sealed package on microbial inactivation and quality attributes of fresh pork and beef were tested. Following a 10-min treatment, the microbial-load reductions of Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella Typhimurium were 2.04, 2.54, and 2.68 Log CFU/g in pork-butt samples and 1.90, 2.57, and 2.58 Log CFU/g in beef-loin samples, respectively. Colorimetric analysis showed that DBD-plasma treatment did not significantly affect L* values (lightness) of pork and beef samples, but lowered a* values (redness) significantly after 5- and 7.5-min exposures. The plasma treatment significantly influenced lipid oxidation only after a 10-min exposure. The texture of both types of meat was unaffected by plasma treatment. All sensory parameters of treated and non-treated samples were comparable except for taste, which was negatively influenced by the plasma treatment (P < 0.05). This thin-layer DBD-plasma system can be applied to inactivate foodborne pathogens. The observed minor deterioration of meat quality might be prevented by the use of hurdle technology. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Jet noise control using the dielectric barrier discharge plasma actuators

    NASA Astrophysics Data System (ADS)

    Kopiev, V. F.; Bityurin, V. A.; Belyaev, I. V.; Godin, S. M.; Zaitsev, M. Yu.; Klimov, A. I.; Kopiev, V. A.; Moralev, I. A.; Ostrikov, N. N.

    2012-07-01

    We study experimentally how plasma actuators operating on the basis of surface barrier high-frequency discharge affect jet noise characteristics. The results of investigations of air jets (100-200 m/s) have demonstrated that the studied plasma actuators have control authority over the noise characteristics of these jets. An actuator's effect on the jet in the applied configuration is related to acoustic discharge excitation and to a large extent is similar to the well-known Vlasov-Ginevsky effect. It has been shown that jet excitation in the case of St ˜ 0.5 using the barrier-discharge plasma actuator leads to broadband amplification of jet sound radiation. The jet excitation in the case of St > 2 leads to broadband noise reduction if the action is sufficiently intensive.

  5. Discharge dynamics of pin-to-plate dielectric barrier discharge at atmospheric pressure

    SciTech Connect

    Sun Liqun; Huang, Xiaojiang; Zhang Jie; Zhang Jing; Shi, J. J.

    2010-11-15

    The discharge dynamics of pin-to-plate dielectric barrier discharge was studied in atmospheric helium at 20 kHz. The discharge was predominately ignited in positive half cycle of applied voltage with sinusoidal waveform. The temporal evolution of the discharge was investigated vertically along the discharge gap and radically on the dielectric surface by time resolved imaging. It is found that a discharge column with a diameter of 2 mm was ignited above the pin electrode and expanded toward a plate electrode. On the dielectric surface with space charge accumulation, plasma disk in terms of plasma ring was formed with radius up to 25 mm. The expansion velocity of plasma ring can reach a hypersonic speed of 3.0 km/s. The ionization wave due to electron diffusion is considered to be the mechanism for plasma ring formation and dynamics.

  6. Barriers to discharge from inpatient rehabilitation: a teamwork approach.

    PubMed

    Cruz, Lisanne Catherine; Fine, Jeffrey S; Nori, Subhadra

    2017-03-13

    Purpose In order to prevent adverse events during the discharge process, coordinating appropriate community resources, medication reconciliation, and patient education needs to be implemented before the patient leaves the hospital. This coordination requires communication and effective teamwork amongst staff members. In order to address these concerns, the purpose of this paper is to incorporate the TeamSTEPPS principles to develop a discharge plan that would best meet the needs of the patients as they return to the community. Design/methodology/approach Through a gap analysis, barriers to discharge were identified from the following disciplines: nursing, social work, physical and occupational therapy, psychology, and rehabilitation physician. To improve communication, weekly meetings and twice-weekly huddles were implemented so that concerns regarding discharge obstacles could be identified and resolved. Visibility of discharge dates were improved by use of graduation certificates in patient rooms and green ribbons on patient wheelchairs. Findings After implementation of this discharge intervention, length of stay was reduced providing cost savings to the hospital, patient satisfaction on HCAHP surveys improved and demonstrated patient satisfaction with the discharge process, and readmission rates improved. Originality/value This study demonstrated that effective teamwork and communication can improve patient safety and satisfaction during the discharge period.

  7. Plasma assisted ignition with nanosecond surface dielectric barrier discharge. Two modes of nanosecond surface discharge

    NASA Astrophysics Data System (ADS)

    Shcherbanev, Sergey; Popov, Nikolay; Starikovskaia, Svetlana; LPP Team; LIA France-Russia Collaboration

    2016-09-01

    Nanosecond surface dielectric barrier discharge (nSDBD) is an efficient tool for a multi-point plasma-assisted ignition of combustible mixtures at elevated pressures. In combustible mixtures, nSDBD initiates numerous combustion waves propagating from the electrode. This work presents a comparative experimental study of the surface dielectric barrier discharge initiated by high voltage pulses (U =+/-(20-60) kV) of different polarities in air at elevated pressures (P =1 -12 bar). Discharge morphology, deposited energy, and spectroscopy of the discharges are analyzed. Differences between the discharges of the different polarity, as well as the changes in the discharge morphology with changing of a gas mixture composition, are discussed. The initiation of combustion with nSDBD was studied experimentally at high initial pressures up to 6 bar on the example of lean H2/Air. The ignition is initiated with two different discharge modes: streamer and filamentary. The influence of the discharge structure and energy deposition on the ignition is demonstrated. Three regimes of multi-point ignition were observed: ignition with a few kernels, quasi-uniform ignition along the edge of high voltage electrodes and ignition along the plasma channels.

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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

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

    NASA Astrophysics Data System (ADS)

    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

  10. A dielectric barrier discharge based ion source for a sensitive and versatile chemical ionization time of flight mass spectrometer instrument using the negative ion mode

    NASA Astrophysics Data System (ADS)

    Albrecht, Sascha; Afchine, Armin; Barthel, Jochen; Dick, Markus; Rongen, Heinz; Franzke, Joachim; Stroh, Fred; Benter, Thorsten

    2017-04-01

    Chemical ionization mass spectrometry (CIMS) provides high sensitivity for ultra-sensitive trace gas measurements in the atmosphere. The presented ion source is used to replace radioactive Po ion sources. First in-field test runs have been done using an airborne instrument flown on the StratoClim campaign in Greece, Kalamata 2016. Especially stratospheric measurements at ambient pressures lower than 100 hPa require improved sensitivity. Therefore, a chemical ionization (CI) time-of-flight (TOF) instrument using a dielectric barrier discharge (DBD) ion source and a high-transmission transfer stage has been set-up and characterized. A new concept including the ion molecule reaction (IMR) zone inside an ion funnel is used. The focus will be on the brilliant DBD ion source, which also can be used to generate ion precursors in the plasma. Thereby multiple reactants can be generated having a versatile ion source. To finally judge the brilliance of the DBD ion source it is compared to a 10 mCi Po ion source. These measurements are highlighting that even more ions are generated in the DBD ion source compared to a 10 mCi Po ion source. However, first measurements with good sensitivity have been made, employing the CIMS instrument described. The analyte gas is introduced into the first ion funnel and mixed with the ion source gas flow. It has been discovered that the mixing in the IMR funnel is critical in terms of sensitivity and was therefore optimized. The ion funnel achieves a transmission of 40% working at 50 hPa pressure and using a gas flow of 1 slm. The complete transfer stage achieves a high transmission of around 10 % for gas phase ions and therefore enables a high sensitivity combined with the brilliant DBD ion source. A detection limit better than 100 pptV was determined for SO2 using CO3- ions. Further-on a fast exchange of the reactants is possible. NO3-, CO3-, I- and SF6- have been successfully tested and can be generated in the DBD from low ppm or even ppb

  11. Study of Periodic Forcing with a Dielectric Barrier Discharge Device for the Control of Flow Separation on a NACA 0012

    NASA Astrophysics Data System (ADS)

    Dygert, Joseph P.

    The continued high global demand for passenger and freight air traffic as well as increased use of unmanned aerial vehicles (UAVs), in spite of rising fuel costs and several tragic cases involving loss-of-control events, has resulted in researchers examining alternative technologies, which would result in safer, more reliable, and superior performing aircraft. Aerodynamic flow control may be the most promising approach to this problem having already proven its ability to enable higher flow efficiency while also simultaneously improving overall flow control. Recent research in the area of aerodynamic control is transitioning from traditional mechanical flow control devices such as slats and flaps to plasma actuators. Plasma actuators offer an inexpensive and energy efficient method of flow control. In addition, plasma actuator technology has the potential of application to a host of other aircraft performance parameters including applications in radar mitigation and in situ wing deicing. Dielectric Barrier Discharge (DBD), one of the most widely studied forms of plasma actuation, employs an electrohydrodynamic (EHD) device, which uses dominant electric fields and the respective electrically related body forces for actuation. Unlike momentum jets or other traditional flow control methods used on wings and tail surfaces, a DBD device operates without moving components or injecting any mass into the flow stream. Work performed focuses on qualitatively investigating experimentally the use of DBD devices for flow separation control on a NACA 0012-based 2D wing model. Flow visualization techniques illuminated flow seed particles around the model to determine the state of the flow (i.e., attached or separated) for various actuator cases. The DBD was operated in a steady-on mode as well as for three different pulsing frequencies (only for low power testing) based on the Strouhal frequency for each flight condition and compared to the clean (i.e., plasma off) case. Some of

  12. One-equation modeling and validation of dielectric barrier discharge plasma actuator thrust

    NASA Astrophysics Data System (ADS)

    Yoon, Jae-San; Han, Jae-Hung

    2014-10-01

    Dielectric barrier discharge (DBD) plasma actuators with an asymmetric electrode configuration can generate a wall-bounded jet without mechanical moving parts, which require considerable modifications of existing aeronautical objects and which incur high maintenance costs. Despite this potential, one factor preventing the wider application of such actuators is the lack of a reliable actuator model. It is difficult to develop such a model because calculating the ion-electric field and fluid interaction consume a high amount calculation effort during the numerical analysis. Thus, the authors proposed a semi-empirical model which predicted the thrust of plasma actuators with a simple equation. It gave a numeric thrust value, and we implemented the value on a computational fluid dynamics (CFD) solver to describe the two-dimensional flow field induced by the actuator. However, the model had a narrow validation range, depending on the empirical formula, and it did not fully consider environment variables. This study presents an improved model by replacing the empirical formulae in the previous model with physical equations that take into account physical phenomena and environmental variables. During this process, additional operation parameters, such as pressure, temperature and ac waveforms, are newly taken to predict the thrust performance of the actuators with a wider range of existing parameters, the thickness of the dielectric barrier, the exposed electrode, the dielectric constant, the ac frequency and the voltage amplitude. Thrust prediction curves from the model are compared to those of earlier experimental results, showing that the average error is less than 5% for more than one hundred instances of data. As in the earlier work, the predicted thrust value is implemented on a CFD solver, and two-dimensional wall-jet velocity profiles induced by the actuator are compared to the previous experimental results.

  13. Numerical studies of independent control of electron density and gas temperature via nonlinear coupling in dual-frequency atmospheric pressure dielectric barrier discharge plasmas

    SciTech Connect

    Zhang, Z. L.; Nie, Q. Y. Wang, Z. B.; Gao, X. T.; Kong, F. R.; Sun, Y. F.; Jiang, B. H.

    2016-07-15

    Dielectric barrier discharges (DBDs) provide a promising technology of generating non-equilibrium cold plasmas in atmospheric pressure gases. For both application-focused and fundamental studies, it is important to explore the strategy and the mechanism for enabling effective independent tuning of key plasma parameters in a DBD system. In this paper, we report numerical studies of effects of dual-frequency excitation on atmospheric DBDs, and modulation as well as separate tuning mechanism, with emphasis on dual-frequency coupling to the key plasma parameters and discharge evolution. With an appropriately applied low frequency to the original high frequency, the numerical calculation demonstrates that a strong nonlinear coupling between two frequencies governs the process of ionization and energy deposition into plasma, and thus raises the electron density significantly (e.g., three times in this case) in comparisons with a single frequency driven DBD system. Nevertheless, the gas temperature, which is mainly determined by the high frequency discharge, barely changes. This method then enables a possible approach of controlling both averaged electron density and gas temperature independently.

  14. Direct analysis of anabolic steroids in urine using Leidenfrost phenomenon assisted thermal desorption-dielectric barrier discharge ionization mass spectrometry.

    PubMed

    Saha, Subhrakanti; Mandal, Mridul Kanti; Nonami, Hiroshi; Hiraoka, Kenzo

    2014-08-11

    Rapid detection of trace level anabolic steroids in urine is highly desirable to monitor the consumption of performance enhancing anabolic steroids by athletes. The present article describes a novel strategy for identifying the trace anabolic steroids in urine using Leidenfrost phenomenon assisted thermal desorption (LPTD) coupled to dielectric barrier discharge (DBD) ionization mass spectrometry. Using this method the steroid molecules are enriched within a liquid droplet during the thermal desorption process and desorbed all-together at the last moment of droplet evaporation in a short time domain. The desorbed molecules were ionized using a dielectric barrier discharge ion-source in front of the mass spectrometer inlet at open atmosphere. This process facilitates the sensitivity enhancement with several orders of magnitude compared to the thermal desorption at a lower temperature. The limits of detection (LODs) of various steroid molecules were found to be in the range of 0.05-0.1 ng mL(-1) for standard solutions and around two orders of magnitude higher for synthetic urine samples. The detection limits of urinary anabolic steroids could be lowered by using a simple and rapid dichloromethane extraction technique. The analytical figures of merit of this technique were evaluated at open atmosphere using suitable internal standards. The technique is simple and rapid for high sensitivity and high throughput screening of anabolic steroids in urine. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Decomposition treatment of SO2F2 using packed bed DBD plasma followed by chemical absorption.

    PubMed

    Nie, Yong; Zheng, Qifeng; Liang, Xiaojiang; Gu, Dayong; Lu, Meizhen; Min, Min; Ji, Jianbing

    2013-07-16

    The technology of packed bed dielectric barrier discharge (DBD) plasma followed by a chemical absorption has been developed and was found to be an efficient way for decomposition treatment of sulfuryl fluoride (SO2F2) in simulated residual fumigant. The effects of energy density, initial SO2F2 concentration, and residence time on the removal efficiency of SO2F2 for the DBD plasma treatment alone were investigated. It was found that the SO2F2 could be removed completely when initial volume concentration, energy density, and residence time were 0.5%, 33.9 kJ/L, and 5.1 s, respectively. The removal mechanism of SO2F2 in the packed bed DBD reactor was discussed. Based on the detailed analysis of SO2F2 molecular stability and its exhaust products in the DBD plasma reactor, it was concluded that the energetic electrons generated in the packed bed DBD reactor played a key role on the removal of SO2F2, and the major decomposition products of SO2F2 detected were SO2, SiF4, and S (Sulfur). Among these products, SiF4 was formed by the F atom reacted with the filler-quartz glass beads (SiO2) in the packed bed DBD reactor. Aqueous NaOH solution was used as the chemical absorbent for the gaseous products of SO2F2 after plasma pretreatment. It was found that the gaseous products in the plasma exhaust could be absorbed and fixed by the subsequent aqueous NaOH solution.

  16. Delay of natural transition with dielectric barrier discharges

    NASA Astrophysics Data System (ADS)

    Duchmann, A.; Grundmann, S.; Tropea, C.

    2013-03-01

    Delay of boundary-layer transition along a flat plate with adverse pressure gradient is achieved via dielectric barrier discharges. In contrast to earlier investigations, transition is initiated by naturally occurring Tollmien-Schlichting waves. A single dielectric barrier discharge actuator is used to create a body force that locally alters the flow stability leading to an attenuation of broadband disturbances. Hot-wire measurements characterize the resulting transition delay, and particle image velocimetry clarifies the local influence on the velocity profiles. Linear stability theory is applied to analyze a numerical solution of this boundary-layer flow, showing good agreement with the experimentally measured data. The stability analysis shows that disturbances are locally attenuated and transition is correctly predicted to occur at Reynolds numbers increased by 10 %. In contrast to previous investigations, the experiments are conducted at a reasonably high free-stream velocity of 20 m/s paving the way for planned in-flight experiments.

  17. Experimental and computational study of dielectric barrier discharges for environmental applications

    NASA Astrophysics Data System (ADS)

    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

  18. Dielectric barrier discharge plasma treatment on E. coli: Influence of CH{sub 4}/N{sub 2}, O{sub 2}, N{sub 2}/O{sub 2}, N{sub 2}, and Ar gases

    SciTech Connect

    Majumdar, Abhijit; Hippler, Rainer; Singh, Rajesh Kumar; Palm, Gottfried J.

    2009-10-15

    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: CH{sub 4}/N{sub 2} (1:2), O{sub 2}, N{sub 2}/O{sub 2} (1:1), N{sub 2}, 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 CH{sub 4}/N{sub 2} plasma exhibits relatively higher sterilization property toward E. coli compared to plasma generated by using O{sub 2}, N{sub 2}/O{sub 2}, N{sub 2}, 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 CH{sub 4}/N{sub 2} and O{sub 2} 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.

  19. Functionalization Of Polymers Using N2 Pulsed Dielectric Barrier Discharge

    DTIC Science & Technology

    2007-06-01

    wettability of the material through the inclusion of polar functional groups. Through the use of atmospheric pulsed-dielectric barrier discharges...work, many have used air and oxygen plasmas operating at atmospheric conditions to enhance the wettability of the polymer surface through the...An alternative method that has been explored to increase adhesion and wettability of these hydrophobic surfaces is the selective functionalization

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

    SciTech Connect

    Meichle, R.H.

    1994-09-29

    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.

  1. An ultraviolet barrier-discharge OH molecular lamp

    SciTech Connect

    Sosnin, E A; Erofeev, M V; Avdeev, S M; Panchenko, Aleksei N; Panarin, V A; Skakun, V S; Tarasenko, Viktor F; Shitts, D V

    2006-10-31

    The energy and spectral parameters of a barrier discharge in a mixture of argon with hydroxyl {sup .}OH are studied experimentally. A sealed lamp with the radiation intensity maximum at {lambda} = 309.2 nm, an emitting surface area of {approx}700 cm{sup 2}, and a radiant excitance of 1.5 mW cm{sup -2} has been fabricated. The radiant power of the lamp is 1.1 W. (laser applications and other topics in quantum electronics)

  2. Characterization of a dielectric barrier discharge in controlled atmosphere

    NASA Astrophysics Data System (ADS)

    Kogelheide, Friederike; Offerhaus, Björn; Bibinov, Nikita; Bracht, Vera; Smith, Ryan; Lackmann, Jan-Wilm; Awakowicz, Peter; Stapelmann, Katharina; Bimap Team; Aept Team

    2016-09-01

    Non-thermal atmospheric-pressure plasmas are advantageous for various biomedical applications as they make a contact- and painless therapy possible. Due to the potential medical relevance of such plasma sources further understanding of the chemical and physical impact on biological tissue regarding the efficacy and health-promoting effect is necessary. The knowledge of properties and effects offers the possibility to configure plasmas free of risk for humans. Therefore, tailoring the discharge chemistry in regard to resulting oxidative and nitrosative effects on biological tissue by adjusting different parameters is of growing interest. In order to ensure stable conditions for the characterization of the discharge, the used dielectric barrier discharge was mounted in a vessel. Absolutely calibrated optical emission spectroscopy was carried out to analyze the electron density and the reduced electric field. The rather oxygen-based discharge was tuned towards a more nitrogen-based discharge by adjusting several parameters as reactive nitrogen species are known to promote wound healing. Furthermore, the impact of an ozone-free discharge has to be studied. This work was funded by the German Research Foundation (DFG) with the packet grant PAK 816 `Plasma Cell Interaction in Dermatology'.

  3. Study a compound orthorhombic lattice pattern in dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Wang, Hao; Dong, Lifang; Gao, Xing; Liu, Weibo; Wei, Lingyan; Pan, Yuyang

    2016-12-01

    The compound orthorhombic lattice pattern which is composed of the bright spot and the dim spot is observed for the first time in a dielectric barrier discharge system. It is found that the dim spot is located at the gravity center of the surrounding three bright spots. The discharge bifurcates from a square lattice, hexagon pattern to compound orthorhombic lattice pattern and finally changes to an irregular pattern. The phase diagram of the pattern types as a function of the applied voltage and the argon concentration is given. The spatio-temporal dynamics of the pattern is studied by the time correlation measurement and the high speed video camera images. Results show that the dim spot is formed by both volume discharge and surface discharge induced by the bright spot. The differences of plasma parameters between the bright spots and the dim spots obtained by optical emission spectroscopy verify that the dim spot is formed by both volume discharge and surface discharge. To better understand the mechanism of firing of the dim spots for the same conditions as in the first phase diagram, the phase diagram of the mechanism of firing of the dim spots as a function of the gas pressure and the argon concentration is given. The simulation of the electric fields of wall charges accumulated by bright spots further verifies that the bright spot has an effect on the formation of dim spot.

  4. The electrical characteristics of the dielectric barrier discharges

    SciTech Connect

    Yehia, Ashraf

    2016-06-15

    The electrical characteristics of the dielectric barrier discharges have been studied in this paper under different operating conditions. The dielectric barrier discharges were formed inside two reactors composed of electrodes in the shape of two parallel plates. The dielectric layers inside these reactors were pasted on the surface of one electrode only in the first reactor and on the surfaces of the two electrodes in the second reactor. The reactor under study has been fed by atmospheric air that flowed inside it with a constant rate at the normal temperature and pressure, in parallel with applying a sinusoidal ac voltage between the electrodes of the reactor. The amount of the electric charge that flows from the reactors to the external circuit has been studied experimentally versus the ac peak voltage applied to them. An analytical model has been obtained for calculating the electrical characteristics of the dielectric barrier discharges that were formed inside the reactors during a complete cycle of the ac voltage. The results that were calculated by using this model have agreed well with the experimental results under the different operating conditions.

  5. The electrical characteristics of the dielectric barrier discharges

    NASA Astrophysics Data System (ADS)

    Yehia, Ashraf

    2016-06-01

    The electrical characteristics of the dielectric barrier discharges have been studied in this paper under different operating conditions. The dielectric barrier discharges were formed inside two reactors composed of electrodes in the shape of two parallel plates. The dielectric layers inside these reactors were pasted on the surface of one electrode only in the first reactor and on the surfaces of the two electrodes in the second reactor. The reactor under study has been fed by atmospheric air that flowed inside it with a constant rate at the normal temperature and pressure, in parallel with applying a sinusoidal ac voltage between the electrodes of the reactor. The amount of the electric charge that flows from the reactors to the external circuit has been studied experimentally versus the ac peak voltage applied to them. An analytical model has been obtained for calculating the electrical characteristics of the dielectric barrier discharges that were formed inside the reactors during a complete cycle of the ac voltage. The results that were calculated by using this model have agreed well with the experimental results under the different operating conditions.

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

    SciTech Connect

    Meichle, R.H.

    1994-10-21

    This analysis examines activities associated with the installation of isolation barriers in the K Basins at the Hanford Reservation. This revision adds evaluation of barrier drops on stored fuel and basin floor, identifies fuel which will be moved and addresses criticality issues with sludge. 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 comparisons 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 was 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 classifications.

  7. Dielectric Barrier Discharges in Helium at Atmospheric Pressure: Experiments and Model in the Needle-Plane Geometry

    NASA Astrophysics Data System (ADS)

    Radu, Ion; Bartnikas, Raymond; Wertheimer, Michael

    2002-10-01

    We present an experimental and theoretical modeling study of "dielectric barrier discharges" (DBD) at atmospheric pressure in a needle-plane configuration. Synchronous, Ultra High Speed Imaging (UHSI, using a Princeton Instruments PI-MAX 512RB Digital ICCD Camera System) and real-time dual detection (optical-electrical) diagnostics have been carried out in a flow of He. A phase-resolved synchronizing circuit was used to trigger the ICCD camera's shutter for durations varying from 2 ns up to 100 ms. All diagnostics, including the PI-MAX images, could be precisely synchronized and processed on a PC computer. The high voltage electrode was a steel needle with a sharp point of precisely-machined radius, while a thin (1.6 mm) ceramic (Al2O3) plate with a metallized bottom surface was used as the ground electrode. Three different situations have been studied, namely (i) the bare Al2O3, and with an ultra-thin coatings of (ii) graphite (a semiconductor) or (iii) metal, the latter two at floating potential. The purpose of these experiments was to investigate possible effects of surface charging on the discharge behavior [1]. The axial [y(t)] and radial [x(t)] time evolutions of the discharge have been measured by UHSI, plotted, and found to differ very significantly among cases (i) to (iii). In the needle-plane configuration (like in the plane-plane case), the DBD is characterized by a single pulse per half-period of the applied voltage. A two-dimensional model of the needle-plane discharge, based upon the continuity equations for electrons, ions, excited particles, and the Poisson equation, is developed; it assumes a low degree of ionization, so that the transport coefficients of the gas are uniquely determined by the local electric field [2]. In order to determine the electric field and the electrical potential in the (hyperboloidal) needle-plane geometry, the finite element method is used. We have found excellent agreement between measured and calculated [y(t)] and [x

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

    PubMed Central

    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 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. PMID:23951023

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

    PubMed

    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 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.

  10. Development of a high mass-transfer dielectric barrier discharge reactor dedicated to the degradation of persistent organic pollutants in water

    NASA Astrophysics Data System (ADS)

    Lesage, Olivier; Commenges, Jean-Marc; Morscheidt, Willy; Duten, Xavier; Tatoulian, Michael; Cavadias, Simeon; Ognier, Stephanie

    2013-09-01

    Some organic compounds such as pCBA are refractory to ozone oxidation. In that context, an AOP based on the use of a dielectric barrier discharge (DBD) working in air at atmospheric pressure has been developed. The process consists in a Thin Falling Film Plasma Reactor (TFFPR) where a discharge is created in the gaseous gap between a high voltage electrode and the surface of the water to treat. To improve radical species transfer, a microstructured plate was used to obtain a thin water film flow. Solution of pCBA was treated in the TFFPR with two different plates (SS316L and Brass). The concentrations of pCBA, NO3- and NO2- were measured using liquid chromatography. To understand the influence of the surface of the material, the NOx concentration on the gas phase and to quantify the flux of HO, we made a simulation with a CFD code. Our results indicated that the DBD directly in contact with liquid can be efficient to oxidize persistent molecules (80% after 30 min) and are brought out the production of HO in the liquid phase. Indeed, the simulation showed that 50% of HO are trapped by NO2-. The efficiency can be increasing by avoiding NOx formation. For brass, the efficiency is reduced to 50% due to corrosion reactions of the material.

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

    SciTech Connect

    Hsiao, M.C.; Merritt, B.T.; Penetrante, B.M.; Vogtlin, G.E.; Wallman, P.H.

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  13. Optical emission spectrum of filamentary nanosecond surface dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Shcherbanev, S. A.; Khomenko, A. Yu; Stepanyan, S. A.; Popov, N. A.; Starikovskaia, S. M.

    2017-02-01

    Streamer-to-filament transition is a general feature of high pressure high voltage (HV) nanosecond surface dielectric barrier discharges. The transition was studied experimentally using time- and space-resolved optical emission in UV and visible parts of spectra. The discharge was initiated by HV pulses 20 ns in duration and 2 ns rise time, positive or negative polarity, 20-60 kV in amplitude on the HV electrode. The experiments were carried out in a single-shot regime at initial pressures P  >  3 bar and ambient initial temperature in air, N2, H2:N2 and O2:Ar mixtures. It was shown that the transition to filamentary mode is accompanied by the appearance of intense continuous radiation and broad atomic lines. Electron density calculated from line broadening is characterized by high absolute values and long decay in the afterglow. The possible reasons for the continuous spectra were analyzed.

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

    SciTech Connect

    Chin, O. H.; Lai, C. K.; Choo, C. Y.; Wong, C. S.; Nor, R. M.; Thong, K. L.

    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.

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

    NASA Astrophysics Data System (ADS)

    Chin, O. H.; Lai, C. K.; Choo, C. Y.; Wong, C. S.; Nor, R. M.; Thong, K. L.

    2015-04-01

    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.

  16. Language barriers and understanding of hospital discharge instructions.

    PubMed

    Karliner, Leah S; Auerbach, Andrew; Nápoles, Anna; Schillinger, Dean; Nickleach, Dana; Pérez-Stable, Eliseo J

    2012-04-01

    Effective communication at hospital discharge is necessary for an optimal transition and to avoid adverse events. We investigated the association of a language barrier with patient understanding of discharge instructions. Spanish-speaking, Chinese-speaking, and English-speaking patients admitted to 2 urban hospitals between 2005 and 2008, comparing patient understanding of follow-up appointment type, and medication category and purpose between limited English-proficient (LEP) and English-proficient patients. Of the 308 patients, 203 were LEP. Rates of understanding were low overall for follow-up appointment type (56%) and the 3 medication outcomes (category 48%, purpose 55%, both 41%). In unadjusted analysis, LEP patients were less likely than English-proficient patients to know appointment type (50% vs. 66%; P=0.01), medication category (45% vs. 54%; P=0.05), and medication category and purpose combined (38% vs. 47%; P=0.04), but equally likely to know medication purpose alone. These results persisted in the adjusted models for medication outcomes: LEP patients had lower odds of understanding medication category (odds ratio 0.63; 95% confidence interval, 0.42-0.95); and category/purpose (odds ratio 0.59; 95% confidence interval, 0.39-0.89). Understanding of appointment type and medications after discharge was low, with LEP patients demonstrating worse understanding of medications. System interventions to improve communication at hospital discharge for all patients, and especially those with LEP, are needed.

  17. Language Barriers and Understanding of Hospital Discharge Instructions

    PubMed Central

    Karliner, Leah S.; Auerbach, Andrew; Nápoles, Anna; Schillinger, Dean; Nickleach, Dana; Pérez-Stable, Eliseo J.

    2012-01-01

    Background Effective communication at hospital discharge is necessary for an optimal transition and to avoid adverse events. We investigated the association of a language barrier with patient understanding of discharge instructions. Methods Spanish, Chinese and English speaking patients admitted to two urban hospitals between 2005-2008, comparing patient understanding of follow-up appointment type, and medication category and purpose between limited English proficient (LEP) and English proficient (EP) patients. Results Of the 308 patients, 203 were LEP. Rates of understanding were low overall for follow-up appointment type (56%) and the 3 medication outcomes (category 48%, purpose 55%, both 41%). In unadjusted analysis, LEP were less likely than EP patients to know appointment type (50% vs. 66%; p = .01), medication category (45% vs. 54%; p = .05), and medication category and purpose combined (38% vs. 47%; p = .04), but equally likely to know medication purpose alone. These results persisted in the adjusted models for medication outcomes: LEP patients had lower odds of understanding medication category (OR 0.63; 95% CI 0.42-0.95); and category/purpose (OR 0.59; 95%CI 0.39-0.89). Conclusions Understanding of appointment type and medications post-discharge was low, with LEP patients demonstrating worse understanding of medications. System interventions to improve communication at hospital discharge for all patients, and especially those with LEP, are needed. PMID:22411441

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

    PubMed Central

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

    2015-01-01

    Bacteria can be inactivated through various physical and chemical means, and these have always been the focus of extensive research. To further improve the methodology for these ends, two types of plasma systems were investigated: nano-second pulsed plasma (NPP) as liquid discharge plasma and an Argon gas-feeding dielectric barrier discharge (Ar-DBD) as a form of surface plasma. To understand the sterilizing action of these two different plasma sources, we performed experiments with Staphylococcus aureus (S. aureus) bacteria (wild type) and multidrug resistant bacteria (Penicillum-resistant, Methicillin-resistant and Gentamicin-resistant). We observed that both plasma sources can inactivate both the wild type and multidrug-resistant bacteria to a good extent. Moreover, we observed a change in the surface morphology, gene expression and β-lactamase activity. Furthermore, we used X-ray photoelectron spectroscopy to investigate the variation in functional groups (C-H/C-C, C-OH and C=O) of the peptidoglycan (PG) resulting from exposure to plasma species. To obtain atomic scale insight in the plasma-cell interactions and support our experimental observations, we have performed molecular dynamics simulations to study the effects of plasma species, such as OH, H2O2, O, O3, as well as O2 and H2O, on the dissociation/formation of above mentioned functional groups in PG. PMID:26351132

  19. On the influence of high voltage slope steepness on breakdown and development of pulsed dielectric barrier discharges

    NASA Astrophysics Data System (ADS)

    Höft, H.; Becker, M. M.; Loffhagen, D.; Kettlitz, M.

    2016-12-01

    The influence of the steepness of the applied high voltage (HV) waveform on the characteristics of pulsed dielectric barrier discharges (DBDs) is investigated using a single-filament arrangement with 1 mm gap in 0.1 vol% O2 in N2 at atmospheric pressure. The slope steepness was varied between 75 V ns-1 and 200 V ns-1. The discharge development was recorded with a combined iCCD and streak camera system accompanied by electrical measurements. The analysis was supported by time-dependent, spatially one-dimensional fluid model calculations. A steeper HV slope leads to a higher transferred charge and electrical energy per cycle. The DBD emission structure in the gap features a shorter ‘dark space’ in front of the cathode for steeper HV pulses. The starting velocity of the positive streamer-like propagation at the rising slope of the HV pulses increases with increasing slope steepness, but without influencing the maximal velocity in front of the cathode. At the falling slope, however, smaller propagation velocities for steeper pulses were measured. The modelling results and the measurements of the emission during the pre-phase suggest that the elevated pre-ionisation and higher electrical energy for steeper HV slopes is responsible for most of the observed effects.

  20. Particle-in-Cell Simulation for the Control of Electron Energy Distribution of Dielectric Barrier Discharges at Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Bae, Hyo Won; Yel Lee, Jung; Lee, Ho-Jun; Lee, Hae June

    2011-10-01

    Recently, atmospheric pressure plasmas attract lots of interests for the useful applications such as surface modification and bio-medical treatment. In this study, a particle-in-cell Monte Carlo collision (PIC-MCC) simulation was adopted to investigate the discharge characteristics of a planar micro dielectric barrier discharge (DBD) with a driving frequency from 1 MHz to 50 MHz and with a gap distance from 60 to 500 micrometers. The variation of control parameters such as the gap distance, the driving wave form, and the applied voltage results in the change in the electron energy distribution function (EEDF). Through the relation between the ionization mean free path and the gap size, a significant change of EEDFs is achievable with the decrease of gap distance. Therefore, it is possible to categorize the operation range of DBDs for its applications by controlling the interactions between plasmas and neutral gas for the generation of preferable radicals. This work was supported by the Human Resources Development of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea government Ministry of Knowledge Economy (No. 20104010100670).

  1. Comparison of the rates of phenol advanced oxidation in deionized and tap water within a dielectric barrier discharge reactor.

    PubMed

    Marotta, Ester; Ceriani, Elisa; Schiorlin, Milko; Ceretta, Claudio; Paradisi, Cristina

    2012-12-01

    Electric non-thermalizing discharges provide promising novel means to induce oxidation of organic pollutants in water. The decomposition of phenol in solutions prepared with deionized (milliQ) and tap water was studied and compared in a Dielectric Barrier Discharge (DBD) reactor. Interestingly, a significant rate increase was found in tap with respect to milliQ water. Control experiments proved that this was not the effect of conductivity or of traces of iron or of residual active chlorine from the depuration process operated in the aqueducts of Italian cities. The same increase in efficiency as observed in tap water was instead obtained when phenol was treated in solutions containing bicarbonate anions in the same concentration as present in tap water, an effect attributed to buffering of the solution pH. The role of pH has been investigated thoroughly by measuring the process efficiency over a wide pH range, from 2 to 10, by using different buffer systems to probe reactivity at near neutral pH, the most relevant for drinking water applications, and by testing the effect of different buffer concentrations. These latter experiments failed to detect any significant kinetic effect attributable to the well known reactivity of bicarbonate as quencher of OH radicals. Copyright © 2012 Elsevier Ltd. All rights reserved.

  2. Ozone production in parallel multichannel dielectric barrier discharge from oxygen and air: the influence of gas pressure

    NASA Astrophysics Data System (ADS)

    Yuan, Dingkun; Wang, Zhihua; Ding, Can; He, Yong; Whiddon, Ronald; Cen, Kefa

    2016-11-01

    This research aims to investigate the influence of gas pressure (0.1 Mpa-0.2 Mpa) on ozone generation in a parallel multichannel dielectric barrier discharge (DBD) reactor with a narrow gap (0.2 mm). In addition to determining ozone concentration and ozone yield characteristics with gas pressure variation, this paper examines the possible reasons leading to the inconsistency with previous reported results. All the experimental results are plotted on the basis of specific input energy (SIE) in order to conduct the comparison within identical power density. By reviewing the experimental results, the possible cause leading to the inconsistency concerning gas pressure dependences of ozone generation was found using different comparison bases. Results show that ozone generation is slightly suppressed with an increase of gas pressure with an initial increase in SIE. The results of the ozone yield show that an increase of gas pressure would have a favorable effect on ozone production efficiency with an SIE larger than 400 J l-1 in oxygen while ozone yield reaches the maximum at 0.14 Mpa with an SIE larger than 150 J l-1 in air. Increasing gas pressure would lead to a higher critical SIE value at which ozone yield firstly decreases with an increase of SIE both in oxygen and air. The results of nitrogen oxide byproducts show that both NO x byproducts emission and the discharge poisoning effect are suppressed by increasing gas pressure in air plasmas.

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

    PubMed

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

    2015-09-09

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

  4. Low pressure characterization of dielectric barrier discharge actuators

    NASA Astrophysics Data System (ADS)

    Soni, Jignesh; Roy, Subrata

    2013-03-01

    Dielectric barrier discharge actuators tested for thrust inducement between 13 and 101 kPa ambient air pressure show that as the pressure decreases, the thrust increases to a maximum, then drops steadily approaching zero while the power consumption monotonically increases. The amplification in induced thrust at the peak ranges from a few percent to several folds of the thrust measured at atmospheric condition. The effect is more pronounced for thinner dielectrics at lower operating voltages than thicker dielectrics at higher operating voltages and is fairly independent of the ground electrode width. Results identify several optimal control parameters for high-altitude operations.

  5. Power consumption analysis DBD plasma ozone generator

    NASA Astrophysics Data System (ADS)

    Nur, M.; Restiwijaya, M.; Muchlisin, Z.; Susan, I. A.; Arianto, F.; Widyanto, S. A.

    2016-11-01

    Studies on the consumption of energy by an ozone generator with various constructions electrodes of dielectric barrier discharge plasma (DBDP) reactor has been carried out. This research was done to get the configuration of the reactor, that is capable to produce high ozone concentrations with low energy consumption. BDBP reactors were constructed by spiral- cylindrical configuration, plasma ozone was generated by high voltage AC voltage up to 25 kV and maximum frequency of 23 kHz. The reactor consists of an active electrode in the form of a spiral-shaped with variation diameter Dc, and it was made by using copper wire with diameter Dw. In this research, we variated number of loops coil windings N as well as Dc and Dw. Ozone concentrations greater when the wire's diameter Dw and the diameter of the coil windings applied was greater. We found that impedance greater will minimize the concentration of ozone, in contrary to the greater capacitance will increase the concentration of ozone. The ozone concentrations increase with augmenting of power. Maximum power is effective at DBD reactor spiral-cylinder is on the Dc = 20 mm, Dw = 1.2 mm, and the number of coil windings N = 10 loops with the resulting concentration is greater than 20 ppm and it consumes energy of 177.60 watts

  6. Acoustic Measurements in a Hexamethyldisiloxane-Loaded Low-Temperature Direct Barrier Discharge (DBD) Plasma Effluent: Nozzle Cleaning

    NASA Astrophysics Data System (ADS)

    Burkert, A.; Müller, D.; Paa, W.

    2015-04-01

    Acoustic emission (AE) measurements as well as laser light scattering experiments were performed during SiO2 layer deposition. SiO2 was generated in low-temperature atmospheric plasma torches (≤500 W), which were seeded with hexamethyldisiloxane. These AE measurements can be used to detect the necessity for nozzle cleaning online. The plasma torches were used to obtain high-quality SiO2 coatings. For electrical power of less than 350 W, we observed parasitic SiO2 deposition in the burner nozzle, which decreases the nozzle aperture within several hours of operation time. No parasitic SiO2 deposition inside the burner nozzle was observed when the plasma source was operated at more than 350 W. The reduced nozzle aperture causes increased plasma velocities and acoustic noise. Especially burst-like increases of this acoustic emission were assumed to be correlated to the ejection of particles. This hypothesis could be confirmed by measurements of scattered light from a sheet of laser light at 248 nm. The obtained correlations suggest using a microphone as a low-cost monitor for the degree of parasitic deposition inside the plasma burner nozzle. The threshold for acoustic noise detection has to be chosen low enough to avoid burst-like emission of particles.

  7. Timing Control of Self-organized Dielectric Barrier Discharge and Influence of Discharge Driving Frequency

    NASA Astrophysics Data System (ADS)

    Sugawara, Junichi; Kubota, Yuki; Oki, Hidenori; Mukaigawa, Seiji; Takaki, Koichi

    2015-09-01

    The two-dimensional array of filaments generated by the self-organizing of atmospheric dielectric-barrier discharges has plasma photonic crystal applications. The net generation time for the self-organization of discharge in one cycle is expected to be short because of its self-extinguishing feature, but that did not happen. However, we attempted to shorten the net generation time by implementing a time difference to drive the parallel array discharge units. The timing of the voltage applied to the discharge cells was controlled by the metal-oxide-semiconductor field-effect-transistors of the circuits, which were turned on by a signal from a single peripheral interface controller. The resultant duty cycles of the discharge current duration per cycle were 6% (single cell), 12% (two parallel cells), and 27% (three parallel cells). When the frequency was changed from 100 to 300 kHz, the generation time increased from 0.61 to 0.72 μs (100 kHz), 0.91 to 1.23 μs (200 kHz), and 1.54 to 1.91 μs (300 kHz). According to these results, frequency and maintenance time are proportional. This work was supported by JSPS KAKENHI Grant Numbers 26390094, 24540530.

  8. Turbulent Mixing Layer Control using Ns-DBD Plasma Actuators

    NASA Astrophysics Data System (ADS)

    Singh, Ashish; Little, Jesse

    2016-11-01

    A low speed turbulent mixing layer (Reθo =1282, U1 /U2 = 0 . 28 and U2 = 11 . 8 m / s) is subject to nanosecond pulse driven dielectric barrier discharge (ns-DBD) plasma actuation. The forcing frequency corresponds to a Strouhal number (St) of 0.032 which is the most amplified frequency based on stability theory. Flow response is studied as a function of the pulse energy, the energy input time scale (carrier frequency) and the duration of actuation (duty cycle). It is found that successful actuation requires a combination of forcing parameters. An evaluation of the forcing efficacy is achieved by examining different flow quantities such as momentum thickness, vorticity and velocity fluctuations. In accordance with past work, a dependence is found between the initial shear layer thickness and the energy coupled to the flow. More complex relationships are also revealed such as a limitation on the maximum pulse energy which yields control. Also, the pulse energy and the carrier frequency (inverse of period between successive pulses) are interdependent whereby an optimum exists between them and extreme values of either parameter is inconsonant with the control desired. These observations establish a rich and complex process behind ns-DBD plasma actuation. Air Force Office of Scientific Research (FA9550-12-1-0044).

  9. A new flexible DBD device for treating infected wounds: in vitro and ex vivo evaluation and comparison with a RF argon plasma jet

    NASA Astrophysics Data System (ADS)

    Boekema, B. K. H. L.; Vlig, M.; Guijt, D.; Hijnen, K.; Hofmann, S.; Smits, P.; Sobota, A.; van Veldhuizen, E. M.; Bruggeman, P.; Middelkoop, E.

    2016-02-01

    Cold plasma has been shown to provide a promising alternative antimicrobial treatment for wound healing. We developed and tested a flexible surface dielectric barrier discharge (DBD) and compared it to an argon gas based plasma jet operated remotely with a distance between plasma plume and sample of 8 mm. Tests were conducted using different models: on cultured cells, on ex vivo human skin and on bacteria (Pseudomonas aeruginosa) (on agar, in suspension, in collagen/elastin matrix or on ex vivo human skin), allowing us to directly compare bactericidal with safety aspects under identical conditions. Both plasma devices were highly efficient when used on bacteria in non-buffered solutions, but DBD was faster in reaching the maximum bacterial reduction. Treatment of bacteria on intact skin with DBD resulted in up to 6 log reductions in 3 min. The jet was far less efficient on intact skin. Even after 8 min treatment no more than 2 log reductions were obtained with the jet. Treatment of bacteria in burn wound models with DBD for 6 min resulted in a 4.5 log reduction. Even when using DBD for 6 min on infected burn wound models with colonizing or biofilm phase bacteria, the log reductions were 3.8 or 3.2 respectively. DBD plasma treatment for 6 min did not affect fibroblast viability, whereas a treatment for 8 min was detrimental. Similarly, treatment with DBD or plasma jet for 6 min did also not affect the metabolic activity of skin biopsies. After treatment for 8 min with DBD or plasma jet, 78% or 60% of activity in skin biopsies remained, respectively. Multiple treatments of in vitro burn wound models with surface DBD for 6 min or with plasma jet for 8 min did not affect re-epithelialization. With the flexible surface DBD plasma strip we were able to quickly inactivate large numbers of bacteria on and in skin. Under the same conditions, viability of skin cells or re-epithelialization was not affected. The DBD source has potential for treating

  10. Intensity control of individual DBD plasma filament. II. Fundamental physical mechanism

    NASA Astrophysics Data System (ADS)

    Paliwoda, M. C.; Rovey, J. L.

    2017-05-01

    Filamentary volume dielectric barrier discharge (DBD) produces patterned plasma structures that are currently being explored for reconfigurable metamaterial applications. Previous work has demonstrated control of the presence and intensity of a single DBD plasma filament (within an array of filaments) by biasing a low voltage needle electrode. The results were attributed to redistributed charge inside the DBD due to the modified electric field created by the needle electrode. In the present work, results from a 3D electrodynamic field simulation bolster this argument. Results show that increasing needle bias voltage causes changes in the transverse electric field structure, resulting in redistribution and build-up of surface charge at the needle location. This reduces the needle plasma filament intensity and eventually extinguishes the filament. Specifically, extinguishment of the filament corresponds with the following transitions in the field profile: (1) the applied longitudinal electric field profile along the needle lies below that of the adjacent mesh filament; (2) the surface charge on the dielectric at the needle and adjacent mesh locations is equal; and (3) the transverse electric field reverses direction and forces charge toward the needle location. The calculated surface charge on the dielectric barrier agrees with experimentally measured filament light intensity to within 8%, in agreement with theoretical predictions. Analysis of the data and trends suggests a method for predicting filament pattern formation and reducing the necessary voltage bias.

  11. Ultrasensitive Speciation Analysis of Mercury in Rice by Headspace Solid Phase Microextraction Using Porous Carbons and Gas Chromatography-Dielectric Barrier Discharge Optical Emission Spectrometry.

    PubMed

    Lin, Yao; Yang, Yuan; Li, Yuxuan; Yang, Lu; Hou, Xiandeng; Feng, Xinbin; Zheng, Chengbin

    2016-03-01

    Rice consumption is a primary pathway for human methylmercury (MeHg) exposure in inland mercury mining areas of Asia. In addition, the use of iodomethane, a common fumigant that significantly accelerates the methylation of mercury in soil under sunlight, could increase the MeHg exposure from rice. Conventional hyphenated techniques used for mercury speciation analysis are usually too costly for most developing countries. Consequently, there is an increased interest in the development of sensitive and inexpensive methods for the speciation of mercury in rice. In this work, gas chromatography (GC) coupled to dielectric barrier discharge optical emission spectrometry (DBD-OES) was developed for the speciation analysis of mercury in rice. Prior to GC-DBD-OES analysis, mercury species were derivatized to their volatile species with NaBPh4 and preconcentrated by headspace solid phase microextraction using porous carbons. Limits of detection of 0.5 μg kg(-1) (0.16 ng), 0.75 μg kg(-1) (0.24 ng), and 1.0 μg kg(-1) (0.34 ng) were obtained for Hg(2+), CH3Hg(+), and CH3CH2Hg(+), respectively, with relative standard deviations (RSDs) better than 5.2% and 6.8% for one fiber or fiber-to-fiber mode, respectively. Recoveries of 90-105% were obtained for the rice samples, demonstrating the applicability of the proposed technique. Owing to the small size, low power, and low gas consumption of DBD-OES as well as efficient extraction of mercury species by porous carbons headspace solid phase micro-extraction, the proposed technique provides several advantages including compactness, cost-effectiveness, and potential to couple with miniature GC to accomplish the field speciation of mercury in rice compared to conventional hyphenated techniques.

  12. [Study on Chemical Kinetic Effect of Dielectric Barrier Discharge Plasma].

    PubMed

    Zrang, Peng; Hong, Yan-ji; Shen, Shuang-yan; Ding, Xiao-yu; Ma, Di

    2015-03-01

    To reveal the mechanism of plasma (assisted the ignition process of methane/air further, schematic of dielectric barrier discharge plasma system with atmospheric air was designed and set up, the emission spectrum of dielectric barrier discharge plasma with atmospheric air was measured, and the active particles produced by the interaction of dielectric barrier discharge plasma with atmospheric air were analyzed with the spectrum technology, the ignition model and calculation methods of sensitivity analysis and reaction path analysis were given, effects of NO and O3 on the ignition delay time were simulated, and the chemical kinetics mechanism of NO and O3 assisted ignition was revealed via sensitivity analysis and reaction path analysis. The results show that main excited particles of N2 and O3 are generated via effect of plasma on the atmospheric air, which are converted into active particles of NO(ξ) and O3 in the end, the life of which are longer than any other active particles, effects of plasma on the ignition is simplified as effects of NO(ξ) and O3 on the ignition; NO and O3 could reduce the ignition delay time significantly, but the amplitude decrease with increase of the initial temperature, this is because the rate of ignition is decided by the oxidation rate of CH3, the oxidized pathway of CH3 is R155 and R156 for auto-ignition and their rates are slower when temperature is low, so the ignition delay time of methane/air is longer; NO could reduce the ignition delay time significantly because of the oxidized pathway of CH3 is changed to R327 CH3O2 + NO = CH3O + NO2, R328 CH3 + NO2 = CH3O + NO for NO(ξ) (assisted ignition process from R155 and R156 for auto-ignition; and the chemical kinetic effect is the dominating factor of O3 on the ignition and which change the reaction path.

  13. Characterization of millimetre magnitude atmospheric pressure streamer discharge in pin-to-plane dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Xu, S. J.; Zhang, Y. H.; Yu, Z.; Yao, J.; Zhang, Z. T.

    2013-03-01

    The streamer regime of pin-to-plane dielectric barrier discharge in air was studied by means of fast photography, electrical measurement and photoelectricity. The fast photographs of positive streamer were obtained by CCD camera with micro lens. The exposure time is one microseconds. The images illustrate that the streamer is non-axisymmetric because of some random factors, such as surface charge position, space charge distribution, gas liquidity and so on. In fact, the streamer propagates along bend discharge channel. The bending degree increases with the electric field strengthen. By surveying a mass of images, the diameter of streamer, height of surface charge effect and scope of surface charge was estimate used to describe the shape of streamer.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  16. Synthesis of flat sticky hydrophobic carbon diamond-like films using atmospheric pressure Ar/CH{sub 4} dielectric barrier discharge

    SciTech Connect

    Rincón, R. E-mail: chaker@emt.inrs.ca; Matos, J. de; Chaker, M. E-mail: chaker@emt.inrs.ca; Hendaoui, A.

    2016-06-14

    An Ar/CH{sub 4} atmospheric pressure dielectric barrier discharge (AP-DBD) was used to synthesize sticky hydrophobic diamond-like carbon (DLC) films on glass surface. The film is formed with plasma treatment duration shorter than 30 s, and water contact angles larger than 90° together with contact angle hysteresis larger than 10° can be achieved. According to Fourier transform infrared spectroscopy and atomic force microscopy analysis, hydrocarbon functional groups are created on the glass substrate, producing coatings with low surface energy (∼35 mJ m{sup −2}) with no modification of the surface roughness. To infer the plasma processes leading to the formation of low energy DLC surfaces, optical emission spectroscopy was used. From the results, a direct relationship between the CH species present in the plasma and the carbon concentration in the hydrophobic layer was found, which suggests that the CH species are the precursors of DLC film growth. Additionally, the plasma gas temperature was measured to be below 350 K which highlights the suitability of using AP-DBD to treat thermo-sensitive surfaces.

  17. In Situ Synthesis of Porous Carbons by Using Room-Temperature, Atmospheric-Pressure Dielectric Barrier Discharge Plasma as High-Performance Adsorbents for Solid-Phase Microextraction.

    PubMed

    Lin, Yao; Wu, Li; Xu, Kailai; Tian, Yunfei; Hou, Xiandeng; Zheng, Chengbin

    2015-09-21

    A one-step, template-free method is described to synthesize porous carbons (PCs) in situ on a metal surface by using a room-temperature, atmospheric-pressure dielectric barrier discharge (DBD) plasma. This method not only features high efficiency, environmentally friendliness, and low cost and simple equipment, but also can conveniently realize large-area synthesis of PCs by only changing the design of the DBD reactor. The synthesized PCs have a regulated nestlike morphology, and thus, provide a high specific surface area and high pore volume, which result in excellent adsorption properties. Its applicability was demonstrated by using a PC-coated stainless-steel fiber as a solid-phase microextraction (SPME) fiber to preconcentrate polycyclic aromatic hydrocarbons (PAHs) prior to analysis by gas chromatography with flame ionization detection (GC-FID). The results showed that the fiber exhibited excellent enrichment factors (4.1×10(4) to 3.1×10(5)) toward all tested PAHs. Thus, the PC-based SPME-GC-FID provides low limits of detection (2 to 20 ng L(-1)), good precision (<7.8%), and good recoveries (80-115%) for ultra-sensitive determination of PAHs in real water samples. In addition, the PC-coated fiber could be stable enough for more than 500 replicate extraction cycles.

  18. Influence of argon/oxygen atmospheric dielectric barrier discharge treatment on desizing and scouring of poly (vinyl alcohol) on cotton fabrics

    NASA Astrophysics Data System (ADS)

    Peng, Shujing; Gao, Zhiqiang; Sun, Jie; Yao, Lan; Qiu, Yiping

    2009-09-01

    The effect of argon/oxygen atmospheric dielectric barrier discharge (DBD) treatment on desizing and scouring of polyvinyl alcohol (PVA) on cotton fabric was studied with respect to the treatment duration of 1, 2, 4 and 6 min. X-ray photoelectron spectroscopy (XPS) analysis indicated that oxygen concentration increased for the plasma treated PVA film. Solubility measurement revealed that plasma treatment increased PVA solubility in hot washing but less effective in cold washing. Scanning electron microscopy (SEM) showed that the fiber surfaces were as clean as unsized fibers after 6 min treatment followed by hot washing. Wickability analysis indicated that the capillary heights of plasma treated fabrics increased significantly as the plasma treatment duration increased. The results of the yarn tensile strength test showed that the plasma treatment did not have a negative effect on fabric tensile strength.

  19. Attaining 2D Black Phosphorus and Investigations into Floating-Electrode Dielectric Barrier Discharge Treatment of Solutions

    NASA Astrophysics Data System (ADS)

    Smith, Joshua Benjamin

    -ray diffraction, transmission electron microscopy, and Raman spectroscopy have confirmed successful growth of 2D black phosphorus from red phosphorus thin films for potential uses in 2D semiconductor applications. Additionally, this work discusses some of the chemistry occurring in solution as a result of nonthermal plasma treatment from a floating-electrode dielectric barrier discharge (FE-DBD) configuration. Nonthermal plasma generation allows for the treatment of heat sensitive materials. This has opened up the field to numerous clinical applications of nonthermal plasma treatment including sterilization and wound healing along with potentials in dentistry, dermatology, and even food industries. FE-DBD plasma treatment of water was found to provide a wide-range antimicrobial solution that remained active following 2 years of aging. This plasma-treated water was found to generate a number of ROS/RNS and the formation of these components was studied and verified with UV/Vis and ESR spectroscopy. Enhanced effects were observed when cell culture medium was plasma treated, suggesting the formation of additional reactive species from the plasma treatment of a variety of biomolecules. It is essential to understand these effects for a number of reasons. The possibility to generate a wide range of antimicrobial solutions from air, water, and basic biomolecules could provide a solution for those bacteria that have developed antibiotic resistances. Simultaneously, information into the reaction mechanisms of this FE-DBD plasma treatment can be investigated. All of the applications mentioned above involve complex networks of basic biomolecules, from skin tissue to bacteria cell walls. This work analyzes the effects of plasma treatment on several biomolecule solutions and simultaneously takes aim at understanding some of the potential mechanisms of plasma treatment. Studies were carried out using NMR and GC/MS. This information was used to investigate the possible targeted areas for FE-DBD

  20. Multi-scale modelling of pulsed nanosecond dielectric barrier plasma discharges in plane-to-plane geometry

    NASA Astrophysics Data System (ADS)

    Nagaraja, Sharath; Yang, Vigor; Adamovich, Igor

    2013-04-01

    An integrated theoretical and numerical framework is developed to study the dynamics of energy coupling, gas heating and generation of active species by repetitively pulsed nanosecond dielectric barrier discharges (NS DBDs) in air. The work represents one of the first attempts to simulate, in a self-consistent manner, multiple (more than 100) nanosecond pulses. Detailed information is obtained about the electric-field transients during each voltage pulse, and accumulation of plasma generated species and gas heating over ms timescales. The plasma is modelled using a two-temperature, detailed chemistry scheme, with ions and neutral species in thermal equilibrium at the gas temperature, and electrons in thermal nonequilibrium. The analysis is conducted with pressures and pulsing frequency in the range 40-100 Torr and 1-105 Hz, respectively. The input electrical energy is directly proportional to the number density, and remains fairly constant on a per molecule basis from pulse to pulse. Repetitive pulsing results in uniform production of atomic oxygen in the discharge volume via electron-impact dissociation during voltage pulses, and through quenching of excited nitrogen molecules in the afterglow. The ion Joule effect causes rapid gas heating of ˜40 K/pulse in the cathode sheath and generates weak acoustic waves. Conductive heat loss to the walls during the time interval between voltage pulses prevents overheating of the cathode layer and development of ionization instabilities. A uniform ‘hat-shaped’ temperature profile develops in the discharge volume after multiple pulses, due to chemical heat release from quenching of excited species. This finding may explain experimentally observed volumetric ignition (as opposed to hot-spot ignition) in fuel-air mixtures subject to NS DBD.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    Koban, Ina; Matthes, Rutger; Hübner, Nils-Olaf; Welk, Alexander; Meisel, Peter; Holtfreter, Birte; Sietmann, Rabea; Kindel, Eckhard; Weltmann, Klaus-Dieter; Kramer, Axel; Kocher, Thomas

    2010-07-01

    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.

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

    PubMed Central

    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.

    2015-01-01

    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. PMID:25992482

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

    PubMed

    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

    2015-05-20

    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.

  5. Effect of water vapor on plasma morphology, OH and H2O2 production in He and Ar atmospheric pressure dielectric barrier discharges

    NASA Astrophysics Data System (ADS)

    Du, Yanjun; Nayak, Gaurav; Oinuma, Gaku; Peng, Zhimin; Bruggeman, Peter J.

    2017-04-01

    Although atmospheric pressure dielectric barrier discharges (DBDs) have a long history, the effects of water vapor on the discharge morphology and kinetics have not been studied intensively. We report a simultaneous investigation of discharge morphology, OH and H2O2 production in Ar and He DBDs operated at different water vapor concentrations and powers. The combined study allows us to assess the impact of the discharge morphology and power on the concentration dependence of the OH and H2O2 production. The morphology of the discharge is investigated by ICCD images and current–voltage waveforms. These diagnostics are complemented by broadband absorption and a colorimetric method to measure the gas temperature and the OH and H2O2 concentrations. The number of filaments in Ar DBD increases with increasing water concentration and power. The surface discharge part of the micro-discharge also reduces with increasing water concentration most likely due to a change in surface conductivity of the dielectric with changing water concentration. The OH density in the case of Ar is approximately double the OH density in He for similar power and water admixture. In contrast to the root square dependence of the OH density on the water concentration in He similar to diffuse RF discharges, the OH density in Ar increases for small water concentrations followed by a saturation and reduces for higher water concentrations. This dependence of OH density on water concentration is found to correlate with changes in discharge morphology. An analytical balance of the production and destruction mechanism of H2O2 is shown to be able to reproduce the ratio of the measured OH and H2O2 density for realistic values of electron densities.

  6. Study on hexagonal super-lattice pattern with surface discharges in dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    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. Study on hexagonal super-lattice pattern with surface discharges in dielectric barrier discharge

    SciTech Connect

    Liu, Ying; Dong, Lifang Niu, Xuejiao; Gao, Yenan; Zhang, Chao

    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.

  8. Influence of DBD plasma pretreatment on the deposition of chitosan onto UHMWPE fiber surfaces for improvement of adhesion and dyeing properties

    NASA Astrophysics Data System (ADS)

    Ren, Yu; Ding, Zhirong; Wang, Chunxia; Zang, Chuanfeng; Zhang, Yin; Xu, Lin

    2017-02-01

    The combination treatment of dielectric barrier discharge (DBD) plasma and chitosan coatings was performed on ultrahigh molecular weight polyethylene (UHMWPE) fibers in order to improve the wettability, dyeability and adhesion properties. The properties of UHMWPE fibers coated with chitosan, after being pretreated by DBD plasma, were evaluated through scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The interfacial shear strength (IFSS) between the fiber and the epoxy resin was determined using the single fiber pull-out test technique. The modified UHMWPE fibers were dyed with reactive dyes after the combined treatment. Surface wettability and dyeability were investigated by water contact angle and K/S measurement, respectively. SEM images confirmed that the chitosan was induced onto the surfaces of the UHMWPE fibers after the combined treatment. The XPS analysis showed that the oxygen and nitrogen contents of the UHMWPE fiber surfaces after the combined treatment were higher than that of the fiber modified by chitosan without DBD plasma pretreatment. Meanwhile, the UHMWPE fibers treated with combination of DBD plasma and chitosan treatment had better wettability, dyeability and adhesion property than those of the non-plasma pretreated surfaces, indicating that DBD plasma pretreatment facilitated the deposition of chitosan onto the UHMWPE surfaces.

  9. Transitions of an atmospheric-pressure diffuse dielectric barrier discharge in helium for frequencies increasing from kHz to MHz

    NASA Astrophysics Data System (ADS)

    Boisvert, J.-S.; Margot, J.; Massines, F.

    2017-03-01

    Recent studies have shown that tuning a dielectric barrier discharge (DBD) in the medium-frequency range (MF: from 0.3 to 3 MHz) allows a low-power and a high-power mode to be sustained. In the present article the effect of the driving frequency on a DBD is studied from the low-frequency range (LF: from 30 to 300 kHz) to the high-frequency range (HF: from 3 to 30 MHz). This is achieved using fast imaging together with electrical and spectroscopic diagnostics. At every frequency, a diffuse discharge is sustained. It is observed that at 25 kHz the discharge is an atmospheric-pressure glow discharge (APGD) while at 15 MHz the discharge behaves as a capacitive discharge in the RF-α mode. The usual LF APGD behavior is observed up to 100 kHz. Above 200 kHz, the positive column remains during the whole cycle so that the hybrid mode is sustained. At 5 MHz, the hybrid mode finally turns into the RF-α mode. In addition to the LF APGD, RF-α and hybrid modes obtained when the applied voltage is significantly higher than the ignition value, two other modes can be reached at low applied voltage. A Townsend-like mode is achieved from 50 to 100 kHz while in the medium-frequency range, the Ω mode is sustained. Moreover, only from 1.0 to 2.7 MHz there is a large hysteresis occurring when the discharge transits back and forth from the Ω to the hybrid mode. It is also found that when the frequency increases from 25 kHz to 15 MHz, the rms current increases over two orders of magnitudes while the rms voltage decreases by about 60%. The gas temperature estimated from N2 rotational spectra is always close to room temperature but the discharge is more energy efficient (in the HF range) as a lower fraction of energy turns into gas heating.

  10. DBD reactor design and optimization in continuous AP-PECVD from HMDSO/N2/N2O mixture

    NASA Astrophysics Data System (ADS)

    Hotmar, Petr; Caquineau, Hubert; Cozzolino, Raphaël; Gherardi, Nicolas

    2016-02-01

    Dielectric barrier discharge (DBD) deposition of thin films is increasingly studied as a promising alternative to other non-thermal processes such as low-pressure plasma-enhanced chemical vapor deposition (PECVD) or wet-coating. In this paper we demonstrate how optimizing gas injection in the DBD results in an improvement in the reactor performance. We propose to confine the precursor gas close to the deposition substrate by an additional gas flow. The performance of this design is studied though simulation of mass transport. To optimize the deposited thickness, gas cost and reactor clogging, we assess the influence of the confinement, total gas flow rate and DBD length. The confinement is found to reduce reactor clogging, even for long DBD, and increase the deposit thickness. This increase in thickness requires a proportionate increase in the gas flow-rate, making the gas-cost the main limitation of the proposed design. We show, however, that by fine-tuning the operating conditions a beneficial compromise can be obtained between the three optimization objectives.

  11. Nonintrusive microwave diagnostics of collisional plasmas in Hall thrusters and dielectric barrier discharges

    NASA Astrophysics Data System (ADS)

    Stults, Joshua

    This research presents a numerical framework for diagnosing electron properties in collisional plasmas. Microwave diagnostics achieved a significant level of development during the middle part of the last century due to work in nuclear weapons and fusion plasma research. With the growing use of plasma-based devices in fields as diverse as space propulsion, materials processing and fluid flow control, there is a need for improved, flexible diagnostic techniques suitable for use under the practical constraints imposed by plasma fields generated in a wide variety of aerospace devices. Much of the current diagnostic methodology in the engineering literature is based on analytical diagnostic, or forward, models. The Appleton-Hartree formula is an oft-used analytical relation for the refractive index of a cold, collisional plasma. Most of the assumptions underlying the model are applicable to diagnostics for plasma fields such as those found in Hall Thrusters and dielectric barrier discharge (DBD) plasma actuators. Among the assumptions is uniform material properties, this assumption is relaxed in the present research by introducing a flexible, numerical model of diagnostic wave propagation that can capture the effects of spatial gradients in the plasma state. The numerical approach is chosen for its flexibility in handling future extensions such as multiple spatial dimensions to account for scattering effects when the spatial extent of the plasma is small relative to the probing beam's width, and velocity dependent collision frequency for situations where the constant collision frequency assumption is not justified. The numerical wave propagation model (forward model) is incorporated into a general tomographic reconstruction framework that enables the combination of multiple interferometry measurements. The combined measurements provide a quantitative picture of the spatial variation in the plasma properties. The benefit of combining multiple measurements in a coherent

  12. Control of methicillin-resistant Staphylococcus aureus in planktonic form and biofilms: a biocidal efficacy study of nonthermal dielectric-barrier discharge plasma.

    PubMed

    Joshi, Suresh G; Paff, Michelle; Friedman, Gary; Fridman, Greg; Fridman, Alexander; Brooks, Ari D

    2010-05-01

    Bacterial contamination of surfaces with methicillin-resistant Staphylococcus aureus (MRSA) is a serious problem in the hospital environment and is responsible for significant nosocomial infections. The pathogenic contaminants form biofilms, which are difficult to treat with routine biocides. Thus, a continuous search for novel disinfection methods is essential for effective infection control measures. This demonstration of a novel technique for the control of virulent pathogens in planktonic form as well as in established biofilms may provide a progressive alternative to standard methodology. We evaluated a novel technique of normal atmospheric nonthermal plasma known as floating-electrode dielectric-barrier discharge (FE-DBD) plasma against a control of planktonic and biofilm forms of Escherichia coli, S aureus, multidrug-resistant methicillin-resistant S aureus (MRSA) -95 (clinical isolate), -USA300, and -USA400, using widely accepted techniques such as colony count assay, LIVE/DEAD BacLight Bacterial Viability assay, and XTT (2,3-Bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide) assay. Exposure of free living planktonic forms of E coli, S aureus, and MRSA were rapidly inactivated by DBD plasma. Approximately 10(7) bacterial cells were completely (100%) killed, whereas 10(8) and 10(9) were reduced by approximately 90% to 95% and 40% to 45%, respectively, in less than 60 seconds (7.8 J/cm(2)) and completely disinfected in < or =120 seconds. In established biofilms, the susceptibility of MRSA USA400 was comparable with USA300 but less susceptible than MRSA95 (clinical isolate), S aureus, and E coli (P < .05) to FE-DBD plasma, and plasma was able to kill MRSA more than 60% within 15 seconds (1.95 J/cm(2)). The killing responses were plasma exposure-time dependent, and cell density dependent. The plasma was able disinfect surfaces in a less than 120 seconds. Application of DBD plasma can be a valuable decontamination technique for the removal of

  13. Power distribution between electrons and ions in the dielectric barrier discharge in Xe-Cl2 mixtures and radiation of Xe2* and XeCl* excimer molecules

    NASA Astrophysics Data System (ADS)

    Avtaeva, S. V.

    2015-12-01

    Power distribution between electrons and positive and negative ions and effect of the distribution on radiative efficiency of XeCl* (308 nm) and Xe2* (172 nm) excimer molecules in the dielectric barrier discharge in Xe-Cl2 at various pressures and supply voltages have been studied and discussed. The discharge characteristics were simulated using the 1D fluid model. It was shown that at small chlorine fraction in the mixture ~0.1-1% the most emission of the DBD is observed in the B-->X band of XeCl* molecules at 308 nm: in most cases about 90%-95% of the discharge emission falls on the XeCl* radiation. Highest emission in the B-->X band of XeCl* is observed when electrons adsorb about 50 or a bit higher percent of the discharge power. In this case an optimum between emission power and radiative efficiency of XeCl* UV emission is achieved. When the power absorbed by electrons reaches 70%, the radiation efficiency of Xe2* (at 172 nm) sharply increases and riches 10-11% at small increase or even decrease in radiation efficiency of XeCl* (at 308 nm).

  14. Analysis of the topochemical effects of dielectric-barrier discharge on cellulosic fibers

    Treesearch

    Lorraine C. Vander Wielen; Thomas Elder; Arthur J. Ragauskas

    2005-01-01

    This study investigates the fundamental topochemical effects of dielectric-barrier discharge treatment on bleached chemical pulp and unbleached mechanical pulp fiber surfaces. Fibers were treated with various levels of dielectric-barrier discharge treatment ranging from 0 to 9.27 kw/m2/min. Changes to the fiber surface topochemistry were investigated by atomic force...

  15. Intensity control of individual DBD plasma filament. I. Experiment with a needle electrode

    NASA Astrophysics Data System (ADS)

    Paliwoda, M. C.; Rovey, J. L.

    2017-05-01

    Filamentary volume dielectric barrier discharge (DBD) produces patterned plasma structures that are currently being explored for reconfigurable metamaterial applications. In this work, the presence and intensity of a single filament (within an array of filaments) are controlled by biasing a low voltage needle electrode by less than 7% of the driving voltage. The current, voltage, and time-averaged normalized light intensity were measured while varying the needle voltage through self-biasing resistors. For a 7.5 kV, 3.2 kHz DBD in air, the needle-controlled filament intensity varies from 80% to 0% of the light intensity of surrounding filaments. When the biased voltage prevents a filament from forming, the voltage difference across the air gap and between the electrodes remains well above the breakdown voltage. Redistributed charge inside the DBD rather than the cross-gap voltage difference is the mechanism which controls the filament intensity when surrounding filaments are present. This work presents a method for controlling an array of plasma filaments with needle electrodes, at voltage biases more manageable for a control circuit.

  16. Dielectric Barrier Discharge Plasma Actuators for Flow Control *

    NASA Astrophysics Data System (ADS)

    Corke, Thomas C.; Enloe, C. Lon; Wilkinson, Stephen P.

    2010-01-01

    The term plasma actuator has now been a part of the fluid dynamics flow-control vernacular for more than a decade. A particular type of plasma actuator that has gained wide use is based on a single-dielectric barrier discharge (SDBD) mechanism that has desirable features for use in air at atmospheric pressures. For these actuators, the mechanism of flow control is through a generated body-force vector field that couples with the momentum in the external flow. The body force can be derived from first principles, and the effect of plasma actuators can be easily incorporated into flow solvers so that their placement and operation can be optimized. They have been used in a wide range of internal and external flow applications. Although initially considered useful only at low speeds, plasma actuators are effective in a number of applications at high subsonic, transonic, and supersonic Mach numbers, owing largely to more optimized actuator designs that were developed through better understanding and modeling of the actuator physics. New applications continue to appear through a growing number of programs in the United States, Germany, France, England, the Netherlands, Russia, Australia, Japan, and China. This review provides an overview of the physics and modeling of SDBD plasma actuators. It highlights some of the capabilities of plasma actuators through examples from experiments and simulations.

  17. One step methane conversion to syngas by dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Nozaki, Tomohiro; Abe, Shodai; Moriyama, Shota; Kameshima, Seigo; Okazaki, Ken; Goujard, Valentine; Ağıral, Anıl

    2015-01-01

    Direct conversion of CH4 to syngas (H2 and CO) via CH4 partial oxidation was investigated using a narrow-gap co-axial dielectric barrier discharge reactor. Partial oxidation is initiated by electron impact dissociation of CH4, while complete oxidation is suppressed due to low temperature condition (200-400 °C): CH4 conversion and selectivity for products were determined by the specific energy input (SEI) ambiguously, which is calculated by the input power (J/s) over the total flow rate (cm3/s), producing syngas via direct route with H2/CO = 0.8-1.3 and CO selectivity of 29-41%. However, H2 was oxidized rather preferentially which subsequently produces oxidative species such as H2O2, HOO, and OH; H2 oxidation was promoted by those species and H2 selectivity decreased markedly. Suppression of H2 oxidation is crucial issue to reach higher syngas yield with large H2/CO ratio.

  18. Modeling of vibrational kinetics in CO2 dielectric barrier discharges

    NASA Astrophysics Data System (ADS)

    Ponduri, S.; Becker, M. M.; Loffhagen, D.; Welzel, S.; Sanden, M. C. M. Van De; Engeln, R.

    2014-10-01

    CO2 reduction to CO is considered to improve the prospects of CO2 recycling which in turn could mitigate the greenhouse effect and serve as energy storage. Non equilibrium plasmas were used in the past to achieve high energy efficiencies in dissociating CO2. Non equilibrium distribution in asymmetric stretch modes of CO2, driven by vibrational up-pumping (VV process), has been suggested as key for achieving such high energy efficiencies. In this work, a time-dependent, one dimensional fluid model taking into account balance equations for the densities of all relevant species and electron mean energy is used to investigate the kinetics of VV process in a pure CO2 dielectric barrier discharge. A Treanor like distribution has been observed in CO2 asymmetric modes and the rates of dissociation have been obtained from these distributions. The rates thus obtained have proved to be significantly lower than the rates of other dissociating processes such as electron impact dissociation. The effect of power in-coupling, duration of plasma and pressure on the vibrational distributions and CO production rate is also studied.

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

    SciTech Connect

    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.

  20. The consequences of air flow on the distribution of aqueous species during dielectric barrier discharge treatment of thin water layers

    NASA Astrophysics Data System (ADS)

    Tian, Wei; Lietz, Amanda M.; Kushner, Mark J.

    2016-10-01

    The desired outcomes of wet tissue treatment by dielectric barrier discharges (DBDs) strongly depend on the integrated fluences of reactive species incident onto the tissue, which are determined by power, frequency and treatment time. The reactivity produced by such plasmas is often expected to be proportional to treatment time due to the accumulation of radicals in the liquid over the tissue. However, one of the typically uncontrolled parameters in DBD treatment of liquids and tissue is gas flow, which could affect the delivery of plasma produced radicals to the tissue. Gas flow can redistribute long-lived, plasma produced gas phase species prior to solvating in the liquid, while not greatly affecting the solvation of short-lived species. Gas flow can therefore potentially be a control mechanism for tailoring the fluences of reactive species to the tissue. In this paper, we report on a computational investigation of the consequences of gas flow on treatment of liquid layers covering tissue by atmospheric DBDs by up to 100 pulses. We found that gas flow (through residence time of the gas) can control the production of gas phase species requiring many collisions to form, such as reactive nitrogen species (RNS). The resulting solvation of the RNS in turn controls the production of aqueous species such as \\text{NO}\\text{3aq}- and \\text{ONOO}\\text{aq}- (aq denotes an aqueous species). With the exception of O3 and O3aq, reactive oxygen species (ROS) are less sensitive to gas flow, and so OHaq and H2O2aq, are determined primarily by discharge properties.

  1. Particle-in-cell modeling of gas-confined barrier discharge

    NASA Astrophysics Data System (ADS)

    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.

  2. Particle-in-cell modeling of gas-confined barrier discharge

    SciTech Connect

    Levko, Dmitry; Raja, Laxminarayan L.

    2016-04-15

    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.

  3. Sub-microsecond pulsed atmospheric glow discharges with and without dielectric barrier

    SciTech Connect

    Song Shutong; Guo Ying; Zhang Jie; Zhang Jing; Shi, J. J.; Choe, Wonho

    2012-12-15

    The discharge characteristics and mechanism of glow discharges in atmospheric pressure helium excited by repetitive voltage pulses with and without dielectric barriers are numerically studied using a one-dimensional self-consistent fluid model. The waveforms of discharge current density show that one discharge event occurs during the voltage pulse with bare electrodes and two distinct discharge events happen at the rising and falling phases of voltage pulse with dielectric barrier electrodes, respectively. The spatial profiles of electron and electric field at the time instant of discharge current peak reveal that the electrons are trapped in the plasma bulk with bare electrodes, while the electrons are accumulated in the region between the sheath and plasma bulk with dielectric barrier electrodes. Furthermore, the spatio-temporal evolution of electron density and mean electron energy clearly demonstrate the dynamics of discharge ignition, especially the temporal evolution of sheath above the instantaneous cathode.

  4. Effect of air flow on the micro-discharge dynamics in an array of integrated coaxial microhollow dielectric barrier discharges

    NASA Astrophysics Data System (ADS)

    Nayak, Gaurav; Du, Yanjun; Brandenburg, Ronny; Bruggeman, Peter J.

    2017-03-01

    The micro-discharge properties and evolution in a 2D array of integrated coaxial microhollow dielectric barrier discharges are studied by using highly time-resolved electrical and optical diagnostics. The study is focused on the effect of the gas flow rate and gas residence time on discharge properties. The investigated integrated coaxial microhollow discharge geometry allows operating the discharge at exceptionally small residence times, which can be equal to or even smaller than the discharge period, at reasonable gas flow rates. The gas flow has an impact on gas heating, residual humidity, pre-ionization density and the densities of excited and reactive species produced by previous discharges. A unique voltage–charge plot is obtained with elongated periods without discharge activity. A very significant effect of flow on NO emission is observed that relates to the impact of flow on the NO production in these micro-discharges. Using the emission intensities of molecular bands of the second positive system of nitrogen and the first negative system of the nitrogen ion, effective reduced electric field strengths are obtained with a maximum equal to 870 Td. The reduced electric field decreases with increasing gas flow rate. This behavior is consistent with the reduction of the overall discharge intensity due to a reduced amount of charges present in the discharge gap. Both the flow rate and a reduction in water impurity changing the ion mobility can be responsible for the different effective electric field distributions at the highest and no flow conditions.

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

    NASA Astrophysics Data System (ADS)

    Tian, Wei; Kushner, Mark J.

    2014-04-01

    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, O_{2aq}^{-} , ONOO_{aq}^{-} , NO_{3aq}^{-} and hydronium (H_{3} O_{aq}^{+} ) dominate the water ions with H_{3} O_{aq}^{+} 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.

  6. Experimental investigation of lift enhancement for flying wing aircraft using nanosecond DBD plasma actuators

    NASA Astrophysics Data System (ADS)

    Yao, Junkai; Zhou, Danjie; He, Haibo; He, Chengjun; Shi, Zhiwei; Du, Hai

    2017-04-01

    The effects of the arrangement position and control parameters of nanosecond dielectric barrier discharge (NS-DBD) plasma actuators on lift enhancement for flying wing aircraft were investigated through wind tunnel experiments at a flow speed of 25 m s-1. The aerodynamic forces and moments were obtained by a six-component balance at angles of attack ranging from -4° to 28°. The lift, drag and pitching moment coefficients were compared for the cases with and without plasma control. The results revealed that the maximum control effect was achieved by placing the actuator at the leading edge of the inner and middle wing, for which the maximum lift coefficient increased by 37.8% and the stall angle of attack was postponed by 8° compared with the plasma-off case. The effects of modulation frequency and discharge voltage were also investigated. The results revealed that the lift enhancement effect of the NS-DBD plasma actuators was strongly influenced by the modulation frequency. Significant control effects were obtained at f = 70 Hz, corresponding to F + ≈ 1. The result for the pitching moment coefficient demonstrated that the plasma actuator can induce the reattachment of the separation flows when it is actuated. However, the results indicated that the discharge voltage had a negligible influence on the lift enhancement effect.

  7. Experimental investigation of lift enhancement for flying wing aircraft using nanosecond DBD plasma actuators

    NASA Astrophysics Data System (ADS)

    Junkai, YAO; Danjie, ZHOU; Haibo, HE; Chengjun, HE; Zhiwei, SHI; Hai, DU

    2017-04-01

    The effects of the arrangement position and control parameters of nanosecond dielectric barrier discharge (NS-DBD) plasma actuators on lift enhancement for flying wing aircraft were investigated through wind tunnel experiments at a flow speed of 25 m s‑1. The aerodynamic forces and moments were obtained by a six-component balance at angles of attack ranging from ‑4° to 28°. The lift, drag and pitching moment coefficients were compared for the cases with and without plasma control. The results revealed that the maximum control effect was achieved by placing the actuator at the leading edge of the inner and middle wing, for which the maximum lift coefficient increased by 37.8% and the stall angle of attack was postponed by 8° compared with the plasma-off case. The effects of modulation frequency and discharge voltage were also investigated. The results revealed that the lift enhancement effect of the NS-DBD plasma actuators was strongly influenced by the modulation frequency. Significant control effects were obtained at f = 70 Hz, corresponding to F + ≈ 1. The result for the pitching moment coefficient demonstrated that the plasma actuator can induce the reattachment of the separation flows when it is actuated. However, the results indicated that the discharge voltage had a negligible influence on the lift enhancement effect.

  8. Streamer inhibition for improving force and electric wind produced by DBD actuators

    NASA Astrophysics Data System (ADS)

    Debien, Antoine; Benard, Nicolas; Moreau, Eric

    2012-05-01

    The use of thin wires from 13 to 300 µm in diameter as the exposed electrode of a surface dielectric barrier discharge (SDBD) plasma actuator is experimentally investigated by electrical and optical diagnostics, electrohydrodynamic force measurements and produced electric wind characterization from time-averaged and time-resolved measurements. The streamer inhibition and glow discharge enhancement due to the use of a thin wire active electrode fully modify the topology and the temporal behaviour of the thrust and the electric wind production. With a typical plate-to-plate DBD, the electric wind velocity increases during the negative going cycle. With a wire-to-plate design, both positive and negative going-cycle discharges result in an electric wind velocity increase. The four main quantitative results are as follows: (1) for a power consumption of 1 W cm-1, the force is increased from 65 to 95 mN m-1 when a 13 µm wire is used, (2) this corresponds to a 15% electric wind velocity enhancement, (3) electromechanical efficiency can be increased from 0.1% to 0.25%, (4) these improvements are applied for definition of a new multi-DBD design plasma actuator that allows us to produce a mean velocity of 10.5 m s-1.

  9. Columnar discharge mode between parallel dielectric barrier electrodes in atmospheric pressure helium

    SciTech Connect

    Hao, Yanpeng; Zheng, Bin; Liu, Yaoge

    2014-01-15

    Using a fast-gated intensified charge-coupled device, end- and side-view photographs were taken of columnar discharge between parallel dielectric barrier electrodes in atmospheric pressure helium. Based on three-dimensional images generated from end-view photographs, the number of discharge columns increased, whereas the diameter of each column decreased as the applied voltage was increased. Side-view photographs indicate that columnar discharges exhibited a mode transition ranging from Townsend to glow discharges generated by the same discharge physics as atmospheric pressure glow discharge.

  10. Barriers to effective discharge planning: a qualitative study investigating the perspectives of frontline healthcare professionals

    PubMed Central

    2011-01-01

    Background Studies have shown that effective discharge planning is one of the key factors related to the quality of inpatient care and unnecessary hospital readmission. The perception and understanding of hospital discharge by health professionals is important in developing effective discharge planning. The aims of this present study were to explore the perceived quality of current hospital discharge from the perspective of health service providers and to identify barriers to effective discharge planning in Hong Kong. Methods Focus groups interviews were conducted with different healthcare professionals who were currently responsible for coordinating the discharge planning process in the public hospitals. The discussion covered three main areas: current practice on hospital discharge, barriers to effective hospital discharge, and suggested structures and process for an effective discharge planning system. Results Participants highlighted that there was no standardized hospital-wide discharge planning and policy-driven approach in public health sector in Hong Kong. Potential barriers included lack of standardized policy-driven discharge planning program, and lack of communication and coordination among different health service providers and patients in both acute and sub-acute care provisions which were identified as mainly systemic issues. Improving the quality of hospital discharge was suggested, including a multidisciplinary approach with clearly identified roles among healthcare professionals. Enhancement of health professionals' communication skills and knowledge of patient psychosocial needs were also suggested. Conclusions A systematic approach to develop the structure and key processes of the discharge planning system is critical in ensuring the quality of care and maximizing organization effectiveness. In this study, important views on barriers experienced in hospital discharge were provided. Suggestions for building a comprehensive, system-wide, and policy

  11. A dual-use of DBD plasma for simultaneous NO(x) and SO(2) removal from coal-combustion flue gas.

    PubMed

    Obradović, Bratislav M; Sretenović, Goran B; Kuraica, Milorad M

    2011-01-30

    Dielectric barrier discharge (DBD) was investigated for the simultaneous removal of NO(x) and SO(2) from flue gas in a coal-combustion power plant. The DBD equipment was used in either a mode where flue gas was directed through the discharge zone (direct oxidation), or a mode where produced ozonized air was injected in the flue gas stream (indirect oxidation). Removal efficiencies of SO(2) and NO for both methods were measured and compared. Oxidation of NO is more efficient in the indirect oxidation, while oxidation of SO(2) is more efficient in the direct oxidation. Addition of NH(3), has lead to efficient removal of SO(2), due to thermal reaction, and has also enhanced NO removal due to heterogeneous reactions on the surface of ammonium salt aerosols. In the direct oxidation, concentration of CO increased significantly, while it maintained its level in the indirect oxidation.

  12. Atmospheric air homogenous DBD plasma excited by bipolar nanosecond pulse used for improving the hydrophilic property of polypropylene

    NASA Astrophysics Data System (ADS)

    Yang, Dezheng; Wang, Wenchun; Zhang, Shuai; Liu, Zhijie; Jia, Li; Dai, Leyang

    2013-06-01

    In this paper, an air homogenous dielectric barrier discharge excited by bipolar nanosecond pulse voltage is obtained and used for the surface modification of polypropylene non-woven fabric at atmospheric pressure. Compared with the DBD plasma excited by sine alternating current (AC) voltage, nanosecond pulsed dielectric barrier discharge exhibits obvious advantages, e.g., better discharge homogeneity, lower energy cost, and lower plasma gas temperature etc. Hence it presents the potential application in improving the hydrophilic property of polypropylene non-woven fabric with high energy efficiency and without surface damage. To reduce the water contact angle of the polypropylene surface from 145° to 110°, the average energy cost of the nanosecond pulsed dielectric barrier discharge is only about 0.1 J/cm2, which is about 1/20 of AC dielectric barrier discharge. On the other hand, the surface damage of non-woven fabric induced by nanosecond pulsed dielectric barrier discharge plasma cannot be distinguished by SEM photographs.

  13. Self-stabilized discharge filament in plane-parallel barrier discharge configuration: formation, breakdown mechanism, and memory effects

    NASA Astrophysics Data System (ADS)

    Tschiersch, R.; Nemschokmichal, S.; Bogaczyk, M.; Meichsner, J.

    2017-10-01

    Single self-stabilized discharge filaments were investigated in the plane-parallel electrode configuration. The barrier discharge was operated inside a gap of 3 mm shielded by glass plates to both electrodes, using helium-nitrogen mixtures and a square-wave feeding voltage at a frequency of 2 kHz. The combined application of electrical measurements, ICCD camera imaging, optical emission spectroscopy and surface charge diagnostics via the electro-optic Pockels effect allowed the correlation of the discharge development in the volume and on the dielectric surfaces. The formation criteria and existence regimes were found by systematic variation of the nitrogen admixture to helium, the total pressure and the feeding voltage amplitude. Single self-stabilized discharge filaments can be operated over a wide parameter range, foremost, by significant reduction of the voltage amplitude after the operation in the microdischarge regime. Here, the outstanding importance of the surface charge memory effect on the long-term stability was pointed out by the recalculated spatio-temporally resolved gap voltage. The optical emission revealed discharge characteristics that are partially reminiscent of both the glow-like barrier discharge and the microdischarge regime, such as a Townsend pre-phase, a fast cathode-directed ionization front during the breakdown and radially propagating surface discharges during the afterglow.

  14. Nitrogen oxide removal dynamic process through 15 Ns DBD technique

    NASA Astrophysics Data System (ADS)

    Wang, Xiaojun; Zhang, Lianshui; Lai, Weidong; Liu, Fengliang

    2015-05-01

    Nitrogen oxides exhaust gas assumes the important responsibility on air pollution by forming acid rain. This paper discusses the NO removal mechanism in 15 ns pulse dielectric barrier discharge (DBD) plasma through experimental and simulating method. Emission spectra collected from plasma are evaluated as sourced from N+ and O(3P). The corresponding zero-dimensional model is established and verified through comparing the simulated concentration evolution and the experimental time-resolved spectra of N+. The electron impact ionization plays major role on NO removal and the produced NO+ are further decomposed into N+ and O(3P) through electron impact dissociative excitation rather than the usual reported dissociative recombination process. Simulation also indicates that the removal process can be accelerated by NO inputted at lower initial concentration or electrons streamed at higher concentration, due to the heightened electron impact probability on NO molecules. The repetitive pulse discharge is a benefit for improving the NO removal efficiency by effectively utilizing the radicals generated from the previous pulse under the condition that the pulse period should be shorter enough to ignore the spatial diffusion of radicals. Finally, slight attenuation on NO removal has been experimentally and simulatively observed after N2 mixed, due to the competitive consumption of electrons.

  15. Influence of electrical parameters on H2O2 generation in DBD non-thermal reactor with water mist

    NASA Astrophysics Data System (ADS)

    Xu, Di; Xiao, Zehua; Hao, Chunjing; Qiu, Jian; Liu, Kefu

    2017-06-01

    A dielectric barrier discharge (DBD) reactor is introduced to generate H2O2 by non-thermal plasma with a mixture of oxygen and water mist produced by an ultrasonic atomizer. The results of our experiment show that the energy yield and concentration of the generated H2O2 in the pulsed discharge are much higher than that in AC discharge, due to its high energy efficiency and low heating effect. Micron-sized liquid droplets produced by an ultrasonic atomizer in water mist have large specific surface area, which greatly reduces mass transfer resistance between hydroxyl radicals and water liquids, leading to higher energy yield and H2O2 concentration than in our previous research. The influence of applied voltage, discharge frequency, and environmental temperature on the generated H2O2 is discussed in detail from the viewpoint of the DBD mechanism. The H2O2 concentration of 30 mg l-1, with the energy yield of 2 g kW-1h-1 is obtained by pulsed discharge in our research.

  16. Plasma-catalytic hydrogenation of CO2 for the cogeneration of CO and CH4 in a dielectric barrier discharge reactor: effect of argon addition

    NASA Astrophysics Data System (ADS)

    Zeng, Yuxuan; Tu, Xin

    2017-05-01

    Plasma-catalytic CO2 hydrogenation over a Ni/Al2O3 catalyst for the cogeneration of CO and CH4 has been carried out in a dielectric barrier discharge (DBD) reactor at 150 °C. The presence of the Ni catalyst in the DBD reactor has clearly demonstrated a plasma-catalytic synergistic effect at low temperatures, as the reaction performance of the plasma-catalytic CO2 hydrogenation is significantly higher than that of the sum of the individual processes (plasma process and thermal catalytic process) at the same temperature. The addition of argon (up to 60%) in the reaction enhances the conversion of CO2, the yield of CO and CH4 and the energy efficiency of the plasma process. The formation of metastable argon (Ar*) in the plasma could create new reaction routes which make a significant contribution to the enhanced CO2 conversion and production of CO and CH4. The introduction of Ar decreases the breakdown voltage of the feed gas and promotes charge transfer through the reactor. In addition, we find that the selectivity of CO is almost independent of the Ar content in the feed gas, while increasing the Ar content from 0 to 60% enhances the CH4 selectivity by 85%. This phenomenon suggests that the presence of Ar* might promote the methanation of CO and CO2 with hydrogen at low temperatures. Moreover, the molar ratio of CO/CH4 in the plasma-catalytic hydrogenation of CO2 can also be controlled by changing the Ar content in the feed gas.

  17. Modeling of asymmetric pulsed phenomena in dielectric-barrier atmospheric-pressure glow discharges

    SciTech Connect

    Ha Yan; Wang Huijuan; Wang Xiaofei

    2012-01-15

    Asymmetric current pulses in dielectric-barrier atmospheric-pressure glow discharges are investigated by a self-consistent, one-dimensional fluid model. It is found that the glow mode and Townsend mode can coexist in the asymmetric discharge even though the gas gap is rather large. The reason for this phenomenon is that the residual space charge plays the role of anode and reduces the gap width, resulting in the formation of a Townsend discharge.

  18. Two-dimensional simulation of discharge channels in atmospheric-pressure single dielectric barrier discharges

    SciTech Connect

    Zhang, Jiao; Wang, Yanhui Wang, Dezhen

    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. The influence of partial surface discharging on the electrical characterization of DBDs

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    The determination of internal electrical discharge parameters, such as plasma current and burning voltage, in dielectric barrier discharges (DBDs) relies on an equivalent circuit based on series capacitances for the discharge gap and dielectric material. An effective dielectric capacitance for the discharge can be obtained from Q-V diagrams, also called Lissajous figures, during discharging, which may not be a constant for a given DBD geometry. It has been shown experimentally that microdischarges, which can consist of narrow channels in either diffuse or filamentary form, may not fully cover the available discharge area. Here, we report measurements of the effective dielectric capacitance as a function of applied voltage amplitude in a DBD plasma jet system operating in N2 and derive equations to determine the conductively transferred charge, burning voltage and the proportion of the electrode surface over which discharging occurs when the effective dielectric capacitance is not equal to the dielectric capacitance of the complete electrode area.

  20. Plasma morphology and induced airflow characterization of a DBD actuator with serrated electrode

    NASA Astrophysics Data System (ADS)

    Joussot, R.; Leroy, A.; Weber, R.; Rabat, H.; Loyer, S.; Hong, D.

    2013-03-01

    Plasma morphology and airflow induced by a dielectric barrier discharge (DBD) actuator, whose exposed electrode geometry is designed with a serrated configuration, are investigated in quiescent air and compared with a DBD actuator consisting of electrodes designed with a standard linear strip configuration. ICCD imaging, electrical measurements and three-component laser Doppler velocimetry were carried out to compare various features of these two actuators. With the serrated configuration, ICCD images of the discharge show that streamers are bent, whereas with the linear configuration they are straight. These curved streamers induce a three-dimensional flow topology, which is confirmed by friction line visualization and velocity measurements. Whereas a two-dimensional wall-jet is induced with the linear configuration, a transverse velocity component is measured with the serrated configuration, implying the creation of spanwise-periodic vorticity. Phase-averaged velocity measurements allow the temporal variation of this transverse velocity to be highlighted. On both sides of a tooth, it has qualitatively the same variation as the longitudinal velocity with respect to the negative or positive half-cycles of the high voltage signal. Moreover, with the same electrical operating parameters, the measured longitudinal velocity was higher, particularly at the tips.

  1. Etching of polymers, proteins and bacterial spores by atmospheric pressure DBD plasma in air

    NASA Astrophysics Data System (ADS)

    Kuzminova, A.; Kretková, T.; Kylián, O.; Hanuš, J.; Khalakhan, I.; Prukner, V.; Doležalová, E.; Šimek, M.; Biederman, H.

    2017-04-01

    Many studies proved that non-equilibrium discharges generated at atmospheric pressure are highly effective for the bio-decontamination of surfaces of various materials. One of the key processes that leads to a desired result is plasma etching and thus the evaluation of etching rates of organic materials is of high importance. However, the comparison of reported results is rather difficult if impossible as different authors use diverse sources of atmospheric plasma that are operated at significantly different operational parameters. Therefore, we report here on the systematic study of the etching of nine different common polymers that mimic the different structures of more complicated biological systems, bovine serum albumin (BSA) selected as the model protein and spores of Bacillus subtilis taken as a representative of highly resistant micro-organisms. The treatment of these materials was performed by means of atmospheric pressure dielectric barrier discharge (DBD) sustained in open air at constant conditions. All tested polymers, BSA and spores, were readily etched by DBD plasma. However, the measured etching rates were found to be dependent on the chemical structure of treated materials, namely on the presence of oxygen in the structure of polymers.

  2. A comparison study of toluene removal by two-stage DBD-catalyst systems loading with MnO(x), CeMnO(x), and CoMnO(x).

    PubMed

    Huang, Yifan; Dai, Shaolong; Feng, Fada; Zhang, Xuming; Liu, Zhen; Yan, Keping

    2015-12-01

    This paper studies the toluene removal by a two-stage dielectric barrier discharge (DBD)-catalyst system with three catalysts: MnO(x)/ZSM-5, CoMnO(x)/ZSM-5, and CeMnO(x)/ZSM-5. V-Q Lissajous method, Brunauer-Emmett-Teller (BET) surface area, X-ray diffraction (XRD), and X-ray photoelectron (XPS) are used to characterize the DBD and catalysts. The DBD processing partially oxidizes the toluene, and the removal efficiency has a linear relationship with ozone generation. Three DBD-catalyst systems are compared in terms of their toluene removal efficiency, Fourier transform infrared (FTIR) spectra, carbon balance, CO selectivity, CO2 selectivity, and ozone residual. The results show that the DBD-catalyst system with CoMnO(x)/ZSM-5 performs better than the other two systems. It has the highest removal efficiency of about 93.7%, and the corresponding energy yield is 4.22 g/kWh. The carbon balance and CO2 selectivity of CoMnO(x)/ZSM-5 is also better than the other two catalysts. The measurements of two important byproducts including aerosols and ozone are also presented.

  3. Investigation of planar barrier discharges for coherent nonlinear structures

    NASA Astrophysics Data System (ADS)

    Uzun-Kaymak, I. U.

    2017-02-01

    Nonlinear pattern formations are ubiquitous in nature. One of the analogous configurations in laboratory experiments to such nonlinear systems is the current filament formations observed in glow plasmas. These filaments can generate oscillatory fluctuations in glow, which are also observed in voltage and current measurements. Specifically, semiconductor-gas discharges are known to breed these types of current filaments naturally. The plasma discharge is initiated by applying a DC high voltage to electrodes while they are immersed in nitrogen gas at partial atmospheric pressure. Observed discharge behaves oscillatory in time. Harmonic frequency generation and coherency levels among these modes are investigated. Parametric scans are performed to study the transition to chaotic behavior. Observed results are discussed in detail.

  4. The transition mechanism from a symmetric single period discharge to a period-doubling discharge in atmospheric helium dielectric-barrier discharge

    SciTech Connect

    Zhang, Dingzong; Wang, Yanhui; Wang, Dezhen

    2013-06-15

    Period-doubling and chaos phenomenon have been frequently observed in atmospheric-pressure dielectric-barrier discharges. However, how a normal single period discharge bifurcates into period-doubling state is still unclear. In this paper, by changing the driving frequency, we study numerically the transition mechanisms from a normal single period discharge to a period-doubling state using a one-dimensional self-consistent fluid model. The results show that before a discharge bifurcates into a period-doubling state, it first deviates from its normal operation and transforms into an asymmetric single period discharge mode. Then the weaker discharge in this asymmetric discharge will be enhanced gradually with increasing of the frequency until it makes the subsequent discharge weaken and results in the discharge entering a period-doubling state. In the whole transition process, the spatial distribution of the charged particle density and the electric field plays a definitive role. The conclusions are further confirmed by changing the gap width and the amplitude of the applied voltage.

  5. [Experimental investigation of electrical characteristics and vibrational temperature of barrier discharge in flowing argon].

    PubMed

    Li, Xue-Chen; Liu, Run-Fu; Chang, Yuan-Yuan; Zhao, Huan-Huan

    2013-02-01

    The electrical characteristics and vibrational temperature were investigated as functions of gas gap width, driving frequency and gas flow rate in flowing argon by using a dielectric barrier discharge device with transparent water electrodes. Electrical measurement results show that the discharge with a smaller gas gap width has a higher value of peak current and consumes more power than that with a larger gap width. Both the peak value of discharge current and consumed power increase monotonically with increasing the driving frequency, and decrease with increasing the gas flow rate. Through analyzing the vibrational systems of nitrogen molecule by optical emission spectroscopy, it was found that the vibrational temperature has a similar trend with the peak value of discharge current and consumed power by changing the driving frequency, gas gap width and gas flow rate. These results are important to the industrial applications of atmospheric pressure barrier discharge in flowing gas.

  6. On the mechanism of pattern formation in glow dielectric barrier discharge

    SciTech Connect

    Qiao, Yajun; Li, Ben; Ouyang, Jiting

    2016-01-15

    The formation mechanism of pattern in glow dielectric barrier discharge is investigated by two-dimensional fluid modeling. Experimental results are shown for comparison. The simulation results show that the non-uniform distribution of space charges makes the discharge be enhanced in the high-density region but weakened in its neighborhood, which is considered as an activation-inhibition effect. This effect shows through during a current pulse (one discharge event) but also in a certain period of time after discharge that determines a driving frequency range for the non-uniformity of space charges to be enhanced. The effects of applied voltage, surface charge, electrode boundary, and external field are also discussed. All these factors affect the formation of dielectric-barrier-discharge pattern by changing the distribution or the dynamics of space charges and hence the activation-inhibition effect of non-uniform space charges.

  7. Dielectric barrier hollow cathode discharge and its enhanced performance for light source

    NASA Astrophysics Data System (ADS)

    Lee, Tae Il; Park, Ki Wan; Baik, Hong Koo; Lee, Seong-Min

    2005-12-01

    We invented the dielectric barrier hollow cathode discharge (DBHCD) configuration as a novel light source and studied on the physical properties of discharge and the possibility of the parallel operation of many holes of the DBHCD without additional impedances such as inductance or capacitance. The electrical characteristics and the photo images of discharges sustained in cavity were investigated. The experimental result showed that the surface discharge mode was transformed into a hollow cathode mode according to a decrease of the pD (operating pressure times hole diameter). The parallel operation of the 13 arrays of DBHCD was also possible without additional impedances for limiting current. We measured the relative IR emission efficiency of the coplanar dielectric barrier discharge (CDBD) and DBHCD to evaluate the enhanced performance as light sources. According to the experiment, the 25 arrays of DBHCD result in 30%-enhanced performance in IR emission efficiency compared with CDBD.

  8. Two-dimensional simulation of spatiotemporal generation of dielectric barrier columnar discharges in atmospheric helium

    SciTech Connect

    Huang, Zhiming; Hao, Yanpeng; Yang, Lin; Han, Yongxia; Li, Licheng

    2015-12-15

    A two-dimensional (2D) fluid model is presented to investigate the spatiotemporal generation and dynamic mechanics of dielectric barrier columnar discharges in atmospheric helium. The model was examined with discharge currents measured in experiments and images taken by an intensified charge couple device camera. Based on the model, a columnar discharge was simulated for several cycles after being ignited. The discharge could be regarded as an initial unstable stage for the first three and a half cycles, then a steady state for the following cycles. In the initial stage, the discharge evolves from a uniform pattern into a columnar one. The calculated equipotential lines, 2D radial electric field, and electron density distributions at the edge of uniform discharges show the radial electric field accounts for the shrinking discharge area and the formation of discharge columns in the end. The columnar glow discharges and the Townsend discharges beyond the columns could coexist in the initial stage, and a Townsend discharge might develop into a new glow column in the next half-cycle. The radial electric field surrounding a glow discharge column has an inhibiting effect on the ionization in the peripheral area.

  9. [Study on Square Super-Lattice Pattern with Surface Discharge in Dielectric Barrier Discharge by Optical Emission Spectra].

    PubMed

    Niu, Xue-jiao; Dong, Li-fang; Liu, Ying; Wang, Qian; Feng, Jian-yu

    2016-02-01

    Square super-lattice pattern with surface discharge consisting of central spots and dim spots is firstly observed in the mixture of argon and air by using a dielectric barrier discharge device with water electrodes. By observing the image, it is found that the central spot is located at the centriod of its surrounding four dim spots. The short-exposure image recorded by a high speed video camera shows that the dim spot results from the surface discharges (SDs). The brightness of the central spot and is quite different from that of the dim spot, which indicates that the plasma states of the central spot and the dim spot may be differentiated. The optical emission spectrum method is used to further study the several plasma parameters of the central spot and the dim spot in different argon content. The emission spectra of the N₂ second positive band (C³IIu --> B³ IIg) are measured, from which the molecule vibration temperatures of the central spot and the dim spot are calculated respectively. The broadening of spectral line 696.57 nm (2P₂-->1S₅) is used to study the electron densities of the central spot and the dim spot. It is found that the molecule vibration temperature and electron density of the dim spot are higher than those of the central spot in the same argon content The molecule vibration temperature and electron density of the central spot and the dim spot increase with the argon content increasing from 90% to 99.9%. The surface discharge induced by the volume discharge (VD) has the determinative effect on the formation of the dim spot The experimental results above play an important role in studying the formation mechanism of surface discharg&of square super-lattice pattern with surface discharge. In addition, the studies exert an influence on the application of surface discharge and volume discharge in different fields.

  10. Water Content Effect on Oxides Yield in Gas and Liquid Phase Using DBD Arrays in Mist Spray

    NASA Astrophysics Data System (ADS)

    Chen, Bingyan; Zhu, Changping; Fei, Juntao; He, Xiang; Yin, Cheng; Wang, Yuan; Jiang, Yongfeng; Chen, Longwei; Gao, Yuan; Han, Qingbang

    2016-01-01

    Electric discharge in and in contact with water can accompany ultraviolet (UV) radiation and electron impact, which can generate a large number of active species such as hydroxyl radicals (OH), oxygen radical (O), ozone (O3) and hydrogen peroxide (H2O2). In this paper, a nonthermal plasma processing system was established by means of dielectric barrier discharge (DBD) arrays in water mist spray. The relationship between droplet size and water content was examined, and the effects of the concentrations of oxides in both treated water and gas were investigated under different water content and discharge time. The relative intensity of UV spectra from DBD in water mist was a function of water content. The concentrations of both O3 and nitrogen dioxide (NO2) in DBD room decreased with increasing water content. Moreover, the concentrations of H2O2, O3 and nitrogen oxides (NOx) in treated water decreased with increasing water content, and all the ones enhanced after discharge. The experimental results were further analyzed by chemical reaction equations and commented by physical principles as much as possible. At last, the water containing phenol was tested in this system for the concentration from 100 mg/L to 9.8 mg/L in a period of 35 min. supported by National Natural Science Foundation of China (Nos. 11274092, 51107033, 11404092, 11274091), the Nantong Science and Technology Project, China (No. BK2014024), the Open Project of Jiangsu Province Key Laboratory of Environmental Engineering, China (No. KF2014001), and the Fundamental Research Funds for the Central Universities, China (No. 2014B11414)

  11. Bridges and Barriers: Patients' Perceptions of the Discharge Process Including Multidisciplinary Rounds on a Trauma Unit.

    PubMed

    Zakzesky, Dawn; Klink, Katie; McAndrew, Natalie; Schroeter, Kathryn; Johnson, Grace

    2015-01-01

    Discharge planning is a complex process and ideally begins early in the patient stay. Despite evidence about the importance of discharge readiness, there is limited literature about the patient's view during this transition. The goal of this study was to explore patient perspectives about the discharge process, including multidisciplinary rounds. Multidisciplinary rounding is a process where care providers from various specialties meet to communicate, coordinate patient care, make decisions, and manage responsibilities. The theme found was "bridges and barriers to discharge." Participants identified timelines and tasks, communication, social support, and motivation as helpful and medical setbacks, insurance limitations, and infrequent communication as hindrances to the discharge. Future research is recommended examining efficacy of various discharge models and examination of communication and support throughout hospitalization.

  12. Characterisation of a dielectric barrier surface twin discharge using defined gas mixtures

    NASA Astrophysics Data System (ADS)

    Offerhaus, Björn; Kogelheide, Friederike; Lackmann, Jan-Wilm; Bibinov, Nikita; Smith, Ryan; Bracht, Vera; Stapelmann, Katharina; Awakowicz, Peter; Aept Team; Bimap Team

    2016-09-01

    In the last decades extensive study has been performed on dielectric barrier discharges (DBDs) in several fields of applications of non-thermal atmospheric pressure plasmas. Their applicability ranges from health-promoting effects to the human skin to air decontamination combined with a rather good scalability. Further insight into their physical and chemical properties is mandatory for a proper configuration of plasma sources for a given application. In our case a dielectric barrier surface twin discharge is ignited in different gas mixtures. The surface discharge electrode is made of an Al2O3 plate working as a dielectric barrier and grid-structured copper traces on each side of the plate. The electrode is connected to a HV-HF plasma generator with external transformer. The plasma parameters are determined via OES using an absolutely calibrated Echelle-spectrometer.

  13. Numerical simulation of torus breakdown to chaos in an atmospheric-pressure dielectric barrier discharge

    SciTech Connect

    Zhang, J.; Wang, Y. H.; Wang, D. Z.

    2013-08-15

    Understanding the routes to chaos occurring in atmospheric-pressure dielectric barrier discharge systems by changing controlling parameters is very important to predict and control the dynamical behaviors. In this paper, a route of a quasiperiodic torus to chaos via the strange nonchaotic attractor is observed in an atmospheric-pressure dielectric barrier discharge driven by triangle-wave voltage. By increasing the driving frequency, the discharge system first bifurcates to a quasiperiodic torus from a stable single periodic state, and then torus and phase-locking periodic state appear and disappear alternately. In the meantime, the torus becomes increasingly wrinkling and stretching, and gradually approaches a fractal structure with the nonpositive largest Lyapunov exponent, i.e., a strange nonchaotic attractor. After that, the discharge system enters into chaotic state. If the driving frequency is further increased, another well known route of period-doubling bifurcation to chaos is also observed.

  14. Radial Patterns of Instability and Transport in JT-60U Internal Transport Barrier Discharges

    SciTech Connect

    G. Rewoldt; K.W. Hill; R. Nazikian; W.M. Tang; H Shirai; Y. Sakamoto; Y. Kishimoto; S.Ide; and T. Fujita

    2001-02-27

    One class of internal transport barrier discharges in the JT-60U tokamak is characterized by two relatively flatter regions of the pressure separated by a region with very large pressure gradient. Linear growth rates for toroidal drift-type modes are calculated for discharges in this class, without and with sheared E x B rotation effects. For cases with fully-developed barriers, the results with rotation are consistent with a picture in which the radial electric field generated in part by the steep pressure gradient causes local stabilization, and thus reduction of the local anomalous transport, which allows the steep pressure gradient to persist. If rotation is omitted from the calculation for these cases, or if rotation is included for cases without barriers or with partially developed barriers, the unstable region spreads into the steep pressure gradient region.

  15. The effect of applied voltage frequency on surface dielectric barrier discharge energy

    NASA Astrophysics Data System (ADS)

    Lazukin, A. V.; Gundareva, S. V.; Krivov, S. A.; Nikitin, A. M.; Kavyrshin, D. I.; Fedorovich, S. D.

    2016-11-01

    Results of the experimental investigation of surface dielectric barrier discharge's energy dependence on frequency of applied sinusoidal voltage varying from 0.6 to 40 kHz at atmospheric pressure are presented in the paper for disk electrodes of 20, 50 and 150 μm thick. It is shown that surface dielectric barrier discharge's energy dependence on applied voltage frequency represents an U-shaped curve with a distinct minimum. The value and position of energy minimum are related with thickness of the generating plasma electrode, the barrier material and supply voltage. Increase of plasma heat dissipation owing to selection of the dielectric barrier material changes significantly a trend of the U-shaped curve.

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

    NASA Astrophysics Data System (ADS)

    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.

  17. Functional performance, participation and autonomy after discharge from prosthetic rehabilitation: barriers, facilitators and outcomes.

    PubMed

    van Twillert, Sacha; Stuive, Ilse; Geertzen, Jan H B; Postema, Klaas; Lettinga, Ant T

    2014-10-01

    To examine functional performance, participation and autonomy after discharge from prosthetic rehabilitation and to identify the barriers and facilitators affecting these outcomes. Concurrent mixed-methods design. Quantitative and qualitative data were collected at discharge from rehabilitation, and 3 and 6 months later. The data were integrated during analysis. Thirteen patients with a unilateral lower limb amputation participating for the first time in prosthetic rehabilitation in a Dutch rehabilitation centre. Functional performance was measured using the Two-Minute Walk Test and L test, and participation and autonomy using the Impact on Participation and Autonomy questionnaire. Barriers and facilitators were identified in semi-structured interviews. After discharge, 9 out of 13 patients declined in functional performance. The principal problems in participation were observed in the "autonomy outdoors" and "family role" domains. Many factors affected functioning and participation and many differences were observed in the way that factors acted as barriers or facilitators for individual patients. No time patterns were found for barriers and facilitators. Post-discharge, distinctive fluctuations were observed in functional performance and participation and autonomy in patients with lower limb amputation. It is recommended that patients are educated about these fluctuations and the barriers and facilitators identified in the environmental, personal and medical contexts.

  18. Antitumorigenic effect of atmospheric-pressure dielectric barrier discharge on human colorectal cancer cells via regulation of Sp1 transcription factor.

    PubMed

    Han, Duksun; Cho, Jin Hyoung; Lee, Ra Ham; Bang, Woong; Park, Kyungho; Kim, Minseok S; Shim, Jung-Hyun; Chae, Jung-Il; Moon, Se Youn

    2017-02-22

    Human colorectal cancer cell lines (HT29 and HCT116) were exposed to dielectric barrier discharge (DBD) plasma at atmospheric pressure to investigate the anticancer capacity of the plasma. The dose- and time-dependent effects of DBDP on cell viability, regulation of transcription factor Sp1, cell-cycle analysis, and colony formation were investigated by means of MTS assay, DAPI staining, propidium iodide staining, annexin V-FITC staining, Western blot analysis, RT-PCR analysis, fluorescence microscopy, and anchorage-independent cell transformation assay. By increasing the duration of plasma dose times, significant reductions in the levels of both Sp1 protein and Sp1 mRNA were observed in both cell lines. Also, expression of negative regulators related to the cell cycle (such as p53, p21, and p27) was increased and of the positive regulator cyclin D1 was decreased, indicating that the plasma treatment led to apoptosis and cell-cycle arrest. In addition, the sizes and quantities of colony formation were significantly suppressed even though two cancer promoters, such as TPA and epidermal growth factor, accompanied the plasma treatment. Thus, plasma treatment inhibited cell viability and colony formation by suppressing Sp1, which induced apoptosis and cell-cycle arrest in these two human colorectal cancer cell lines.

  19. Antitumorigenic effect of atmospheric-pressure dielectric barrier discharge on human colorectal cancer cells via regulation of Sp1 transcription factor

    NASA Astrophysics Data System (ADS)

    Han, Duksun; Cho, Jin Hyoung; Lee, Ra Ham; Bang, Woong; Park, Kyungho; Kim, Minseok S.; Shim, Jung-Hyun; Chae, Jung-Il; Moon, Se Youn

    2017-02-01

    Human colorectal cancer cell lines (HT29 and HCT116) were exposed to dielectric barrier discharge (DBD) plasma at atmospheric pressure to investigate the anticancer capacity of the plasma. The dose- and time-dependent effects of DBDP on cell viability, regulation of transcription factor Sp1, cell-cycle analysis, and colony formation were investigated by means of MTS assay, DAPI staining, propidium iodide staining, annexin V-FITC staining, Western blot analysis, RT-PCR analysis, fluorescence microscopy, and anchorage-independent cell transformation assay. By increasing the duration of plasma dose times, significant reductions in the levels of both Sp1 protein and Sp1 mRNA were observed in both cell lines. Also, expression of negative regulators related to the cell cycle (such as p53, p21, and p27) was increased and of the positive regulator cyclin D1 was decreased, indicating that the plasma treatment led to apoptosis and cell-cycle arrest. In addition, the sizes and quantities of colony formation were significantly suppressed even though two cancer promoters, such as TPA and epidermal growth factor, accompanied the plasma treatment. Thus, plasma treatment inhibited cell viability and colony formation by suppressing Sp1, which induced apoptosis and cell-cycle arrest in these two human colorectal cancer cell lines.

  20. A submerged dielectric barrier discharge plasma inactivation mechanism of biofilms produced by Escherichia coli O157:H7, Cronobacter sakazakii, and Staphylococcus aureus

    PubMed Central

    Khan, Muhammad Saiful Islam; Lee, Eun-Jung; Kim, Yun-Ji

    2016-01-01

    A submerged dielectric barrier discharge plasma reactor (underwater DBD) has been used to inactivate biofilm produced by three different food-borne pathogens, namely Escherichia coli O157:H7 (ATCC 438), Cronobacter sakazakii (ATCC 29004), and Staphylococcus aureus (KCCM 40050). The inactivation that were obtained after 90 minutes of plasma operation were found to measure 5.50 log CFU/coupon, 6.88 log CFU/coupon and 4.20 log CFU/coupon for Escherichia coli O157:H7 (ATCC 438), Cronobacter sakazakii (ATCC 29004), and Staphylococcus aureus (KCCM 40050), respectively. Secondary Electron Images (SEI) obtained from Field Emission Scanning Electron Microscopy (FE-SEM) show the biofilm morphology and its removal trend by plasma operation at different time intervals. An attenuated total reflectance Fourier transform infrared (ATR-FTIR) measurement was performed to elucidate the biochemical changes that occur on the bacterial cell and extracellular polymeric substance (EPS) of biofilm during the plasma inactivation process. The ATR-FTIR measurement shows the gradual reduction of carbohydrates, proteins, and lipid and DNA peak regions with increased plasma exposure time. The presence of an EPS layer on the upper surface of the biofilm plays a negative and significant role in its removal from stainless steel (SS) coupons.

  1. Antitumorigenic effect of atmospheric-pressure dielectric barrier discharge on human colorectal cancer cells via regulation of Sp1 transcription factor

    PubMed Central

    Han, Duksun; Cho, Jin Hyoung; Lee, Ra Ham; Bang, Woong; Park, Kyungho; Kim, Minseok S.; Shim, Jung-Hyun; Chae, Jung-Il; Moon, Se Youn

    2017-01-01

    Human colorectal cancer cell lines (HT29 and HCT116) were exposed to dielectric barrier discharge (DBD) plasma at atmospheric pressure to investigate the anticancer capacity of the plasma. The dose- and time-dependent effects of DBDP on cell viability, regulation of transcription factor Sp1, cell-cycle analysis, and colony formation were investigated by means of MTS assay, DAPI staining, propidium iodide staining, annexin V–FITC staining, Western blot analysis, RT-PCR analysis, fluorescence microscopy, and anchorage-independent cell transformation assay. By increasing the duration of plasma dose times, significant reductions in the levels of both Sp1 protein and Sp1 mRNA were observed in both cell lines. Also, expression of negative regulators related to the cell cycle (such as p53, p21, and p27) was increased and of the positive regulator cyclin D1 was decreased, indicating that the plasma treatment led to apoptosis and cell-cycle arrest. In addition, the sizes and quantities of colony formation were significantly suppressed even though two cancer promoters, such as TPA and epidermal growth factor, accompanied the plasma treatment. Thus, plasma treatment inhibited cell viability and colony formation by suppressing Sp1, which induced apoptosis and cell-cycle arrest in these two human colorectal cancer cell lines. PMID:28225083

  2. Optical Characteristics of Barrier Discharge Plasma Based on Mixtures of Cadmium Diiodide Vapors with Gases

    SciTech Connect

    Malinin, A.N.; Polyak, A.V.

    2005-12-15

    The spectral, integrated, and working life characteristics of the radiation from atmospheric pressure gas discharge plasma based on multicomponent mixtures (cadmium diiodide with helium and small admixtures of molecular nitrogen and xenon) are analyzed. A pulsed barrier discharge (pulse repetition rates 5000, 5500, and 6000 Hz; pulse duration {approx}150 ns) is used both to produce the gas discharge plasma and to excite the components of the working mixture. Visible radiation is detected from excimer molecules of cadmium monoiodide and cadmium, xenon, and krypton atoms. Regular features are found in the variations of optical plasma characteristics with pumping pulse repetition rate and with component and quantitative mixture composition.

  3. Three-dimensional patterns in dielectric barrier discharge with “H” shaped gas gap

    SciTech Connect

    Gao, Xing; Dong, Lifang Wang, Hao; Zhang, Hao; Liu, Ying; Liu, Weibo; Fan, Weili; Pan, Yuyang

    2016-08-15

    Three-dimensional (3D) patterns are obtained for the first time in dielectric barrier discharge by a special designed device with “H” shaped gas gap which consists of a single gas layer gap and two double gas layer gaps. Three dimensional spatiotemporal characteristics of discharge are investigated by photomultiplier and intensified charge-coupled device camera. Results show that the discharge first generates in the single gas layer gap and the coupled filaments in the double gas layer gap present the simultaneity characteristics. The formation of 3D patterns is determined by the distribution of the effective field of the applied field and the wall charge field.

  4. Pulsed corona and dielectric-barrier discharge processing of NO in N2

    NASA Astrophysics Data System (ADS)

    Penetrante, B. M.; Hsiao, M. C.; Merritt, B. T.; Vogtlin, G. E.; Wallman, P. H.; Neiger, M.; Wolf, O.; Hammer, T.; Broer, S.

    1996-06-01

    Experimental results on pulsed corona and dielectric-barrier discharge processing of very dilute concentrations of NO in N2 are presented. These NO reduction experiments measure the G value for electron-impact dissociation of N2 and are used to infer the effective electron mean energy in an N2 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±0.5 eV.

  5. Experimental analysis on the nonlinear behavior of DC barrier discharge plasmas

    NASA Astrophysics Data System (ADS)

    Dogan, Mansuroglu; Ilker Umit, Uzun-Kaymak

    2017-01-01

    Nonlinear behavior of glow discharge plasmas is experimentally investigated. The glow is generated between a barrier semiconductor electrode, Chromium doped namely Gallium Arsenide (GaAs:Cr), as a cathode and an Indium-Tin Oxide (ITO) coated glass electrode as an anode, in reverse bias. The planar nature of electrodes provides symmetry in spatial geometry. The discharge behaves oscillatory in the time domain, with single and sometimes multi-periodicities in plasma current and voltage characteristics. In this paper, harmonic frequency generation and transition to chaotic behavior is investigated. The observed current-voltage characteristics of the discharge are discussed in detail.

  6. Hexagonal superlattice pattern consisting of colliding filament pairs in a dielectric barrier discharge

    SciTech Connect

    Dong Lifang; Li Ben; Lu Ning; Li Xinchun; Shen Zhongkai

    2012-05-15

    Colliding-pairs hexagonal superlattice pattern (CPHSP) is studied in a dielectric barrier discharge system. The evolution of CPHSP bifurcating from a hexagonal pattern to chaos is shown. The phase diagrams of CPHSP as a function of discharge parameters are given. From a series of pictures taken by a high speed video camera, collisions between two spots are observed and the superposition of many collisions results in each big spot presenting four small spots on long time scales. Measurements of the correlation between filaments indicate that the pattern is an interleaving of four different transient hexagonal sublattices. Depending on the discharging sequence, the forces exerted on one colliding spot are discussed briefly.

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

    NASA Astrophysics Data System (ADS)

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

    2004-06-01

    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.

  8. Decontamination Efficiency of a DBD Lamp Containing an UV-C Emitting Phosphor.

    PubMed

    Caillier, Bruno; Caiut, José Maurício Almeida; Muja, Cristina; Demoucron, Julien; Mauricot, Robert; Dexpert-Ghys, Jeanette; Guillot, Philippe

    2015-01-01

    Among different physical and chemical agents, the UV radiation appears to be an important route for inactivation of resistant microorganisms. The present study introduces a new mercury-free Dielectric Barrier Discharge (DBD) flat lamp, where the biocide action comes from the UV emission produced by rare-earth phosphor obtained by spray pyrolysis, following plasma excitation. In this study, the emission intensity of the prototype lamp is tuned by controlling gas pressure and electrical power, 500 mbar and 15 W, corresponding to optimal conditions. In order to characterize the prototype lamp, the energetic output, temperature increase following lamp ignition and ozone production of the source were measured. The bactericidal experiments carried out showed excellent results for several gram-positive and gram-negative bacterial strains, thus demonstrating the high decontamination efficiency of the DBD flat lamp. Finally, the study of the external morphology of the microorganisms after the exposure to the UV emission suggested that other mechanisms than the bacterial DNA damage could be involved in the inactivation process. © 2015 The American Society of Photobiology.

  9. Active Control of Airfoil Boundary Layer Separation and Wake using Ns-DBD Plasma Actuators

    NASA Astrophysics Data System (ADS)

    Durasiewicz, Claudia; Castro Maldonado, Jorge; Little, Jesse

    2016-11-01

    Nanosecond pulse driven dielectric barrier discharge (ns-DBD) plasma actuators are employed to control boundary layer separation and the wake of a NACA 0012 airfoil having aspect ratio of three. Ns-DBD plasma actuators are known to operate via a thermal mechanism in contrast to ac-DBDs which are momentum-based devices. Nominally 2D forcing is applied to the airfoil leading edge with pulse energy of 0.35 mJ/cm. Experiments are conducted at a Reynolds number of 0 . 74 ×106 primarily at 18° incidence which is well within the stalled regime. Baseline and controlled flow fields are studied using surface pressure measurements, constant temperature anemometry (CTA) and PIV. Forcing at a dimensionless frequency of F+ = fc /U∞ = 1 . 14 results in reattachment of nominally separated flow to the airfoil surface. Lower frequency forcing is less optimal for separation control, but produces strong fluctuations in the wake which are intended for use in the study of vortex body interaction in the future. Actuation below F+ = 0 . 23 shows behavior consistent with an impulse-like response while forcing in the range 0 . 23

  10. Selective cytotoxic effect of non-thermal micro-DBD plasma

    NASA Astrophysics Data System (ADS)

    Kwon, Byung-Su; Choi, Eun Ha; Chang, Boksoon; Choi, Jeong-Hyun; Kim, Kyung Sook; Park, Hun-Kuk

    2016-10-01

    Non-thermal plasma has been extensively researched as a new cancer treatment technology. We investigated the selective cytotoxic effects of non-thermal micro-dielectric barrier discharge (micro-DBD) plasma in cervical cancer cells. Two human cervical cancer cell lines (HeLa and SiHa) and one human fibroblast (HFB) cell line were treated with micro-DBD plasma. All cells underwent apoptotic death induced by plasma in a dose-dependent manner. The plasma showed selective inhibition of cell proliferation in cervical cancer cells compared to HFBs. The selective effects of the plasma were also observed between the different cervical cancer cell lines. Plasma treatment significantly inhibited the proliferation of SiHa cells in comparison to HeLa cells. The changes in gene expression were significant in the cervical cancer cells in comparison to HFBs. Among the cancer cells, apoptosis-related genes were significantly enriched in SiHa cells. These changes were consistent with the differential cytotoxic effects observed in different cell lines.

  11. Toluene decomposition performance and NOx by-product formation during a DBD-catalyst process.

    PubMed

    Guo, Yufang; Liao, Xiaobin; Fu, Mingli; Huang, Haibao; Ye, Daiqi

    2015-02-01

    Characteristics of toluene decomposition and formation of nitrogen oxide (NOx) by-products were investigated in a dielectric barrier discharge (DBD) reactor with/without catalyst at room temperature and atmospheric pressure. Four kinds of metal oxides, i.e., manganese oxide (MnOx), iron oxide (FeOx), cobalt oxide (CoOx) and copper oxide (CuO), supported on Al2O3/nickel foam, were used as catalysts. It was found that introducing catalysts could improve toluene removal efficiency, promote decomposition of by-product ozone and enhance CO2 selectivity. In addition, NOx was suppressed with the decrease of specific energy density (SED) and the increase of humidity, gas flow rate and toluene concentration, or catalyst introduction. Among the four kinds of catalysts, the CuO catalyst showed the best performance in NOx suppression. The MnOx catalyst exhibited the lowest concentration of O3 and highest CO2 selectivity but the highest concentration of NOx. A possible pathway for NOx production in DBD was discussed. The contributions of oxygen active species and hydroxyl radicals are dominant in NOx suppression.

  12. Selective cytotoxic effect of non-thermal micro-DBD plasma.

    PubMed

    Kwon, Byung-Su; Choi, Eun Ha; Chang, Boksoon; Choi, Jeong-Hyun; Kim, Kyung Sook; Park, Hun-Kuk

    2016-09-07

    Non-thermal plasma has been extensively researched as a new cancer treatment technology. We investigated the selective cytotoxic effects of non-thermal micro-dielectric barrier discharge (micro-DBD) plasma in cervical cancer cells. Two human cervical cancer cell lines (HeLa and SiHa) and one human fibroblast (HFB) cell line were treated with micro-DBD plasma. All cells underwent apoptotic death induced by plasma in a dose-dependent manner. The plasma showed selective inhibition of cell proliferation in cervical cancer cells compared to HFBs. The selective effects of the plasma were also observed between the different cervical cancer cell lines. Plasma treatment significantly inhibited the proliferation of SiHa cells in comparison to HeLa cells. The changes in gene expression were significant in the cervical cancer cells in comparison to HFBs. Among the cancer cells, apoptosis-related genes were significantly enriched in SiHa cells. These changes were consistent with the differential cytotoxic effects observed in different cell lines.

  13. Particle-in-Cell simulations of filamentary structures formation in DBD-tissue interaction

    NASA Astrophysics Data System (ADS)

    Likhanskii, Alexandre; Messmer, Peter

    2011-10-01

    Recent studies demonstrated high potential of the dielectric barrier discharge (DBD) plasmas for medical applications, such as sterilization or tissue regeneration. Despite intensive experimental studies have been conducted, the mechanism of plasma-tissue interaction still remains unclear. One of the open questions for the plasma-medical applications is the mechanism of filamentary structures formation in plasma and their interaction with tissues. Since formation of filaments is a purely kinetic effect, this issue needs to be addressed using kinetic, Particle-In-Cell simulation approach. We will present results of such numerical study. We performed 2D simulations of multiple streamers generation in atmospheric air using Tech-X's 2D/3D hybrid simulation tool VORPAL. We will demonstrate the resolution of the filamentary structure and will report the plasma properties. We will also address the plasma-induced effects on the tissue.

  14. Generation of atmospheric-pressure homogeneous dielectric barrier discharge in air

    NASA Astrophysics Data System (ADS)

    Liu, Wenzheng; Ma, Chuanlong; Li, Zhiyi; Wang, Tahan; Tian, Jia

    2017-05-01

    To generate an atmospheric-pressure homogeneous dielectric barrier discharge (APHDBD) in air, a line-plane electrode with a floating-voltage electrode, which consists of a high-voltage electrode, floating-voltage electrode, air-gap, barrier dielectric, and metal electrode, is proposed. Studies of the electric field of the line-plane electrode with a floating-voltage electrode show that strong electric field areas beneficial for generating initial discharges are formed near the contact point between the high-voltage electrode and the floating-voltage electrode. These areas can provide sufficient and evenly distributed initial electrons for the air-gap with relatively uniform and low electric fields. Thus, a filamentary discharge in the air-gap can be inhibited. Experiments show that the floating-voltage electrode makes it easy to reduce the initial discharge voltage and improve the uniformity of discharge. When the air-gap is 2-8 mm, the discharge occurs in the APHDBD mode, and when it is 9 mm, it changes from diffuse-like to corona discharge.

  15. Dielectric barrier discharge for multi-point plasma-assisted ignition at high pressures.

    PubMed

    Shcherbanev, S A; Stepanyan, S A; Popov, N A; Starikovskaia, S M

    2015-08-13

    Nanosecond surface dielectric barrier discharge (nSDBD) is an efficient tool for a multi-point plasma-assisted ignition of combustible mixtures at elevated pressures. The discharge develops as a set of synchronously propagated from the high-voltage electrode charged channels (streamers), with a typical density up to a few streamers per millimetre of the length of the electrode. In combustible mixtures, nSDBD initiates numerous combustion waves propagating from the electrode. Very little is known about nSDBD at high pressures. This work presents a comparative experimental study of the surface dielectric barrier discharge initiated by high-voltage pulses (U=±(20-60) kV) of different polarities in air at elevated pressures (P=1-6 atm). Discharge morphology, deposited energy and velocity of the discharge front propagation are analysed. Differences between the discharges of positive and negative polarity, as well as the changes in the discharge morphology with changing of a gas mixture composition.

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

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

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

  17. Barriers and facilitators of medication reconciliation processes for recently discharged patients from community pharmacists’ perspectives

    PubMed Central

    Kennelty, Korey A.; Chewning, Betty; Wise, Meg; Kind, Amy; Roberts, Tonya; Kreling, David

    2015-01-01

    Background Community pharmacists play a vital part in reconciling medications for patients transitioning from hospital to community care, yet their roles have not been fully examined in the extant literature. Objectives The objectives of this study were to: 1) examine the barriers and facilitators community pharmacists face when reconciling medications for recently discharged patients; and 2) identify pharmacists’ preferred content and modes of information transfer regarding updated medication information for recently discharged patients. Methods Community pharmacists were purposively and conveniently sampled from the Wisconsin (U.S. state) pharmacist-based research network, Pharmacy Practice Enhancement and Action Research Link (PEARL Rx). Community pharmacists were interviewed face-to-face, and transcriptions from audio recordings were analyzed using directed content analysis. The Theory of Planned Behavior (TPB) guided the development of questions for the semi-structured interviews. Results Interviewed community pharmacists (N = 10) described the medication reconciliation process to be difficult and time-consuming for recently discharged patients. In the context of the TPB, more barriers than facilitators of reconciling medications were revealed. Themes were categorized as organizational and individual-level themes. Major organizational-level factors affecting the medication reconciliation process included: pharmacy resources, discharge communication, and hospital resources. Major individual-level factors affecting the medication reconciliation process included: pharmacists’ perceived responsibility, relationships, patient perception of pharmacist, and patient characteristics. Interviewed pharmacists consistently responded that several pieces of information items would be helpful when reconciling medications for recently discharged patients, including the hospital medication discharge list and stop-orders for discontinued medications. Conclusions The TPB was

  18. Effects of surface dielectric barrier discharge on aerodynamic characteristic of train

    NASA Astrophysics Data System (ADS)

    Dong, Lei; Gao, Guoqiang; Peng, Kaisheng; Wei, Wenfu; Li, Chunmao; Wu, Guangning

    2017-07-01

    High-speed railway today has become an indispensable means of transportation due to its remarkable advantages, including comfortability, convenience and less pollution. The increase in velocity makes the air drag become the main source of energy consumption, leading to receiving more and more concerns. The surface dielectric barrier discharge has shown some unique characteristics in terms of active airflow control. In this paper, the influences of surface dielectric barrier discharge on the aerodynamic characteristics of a scaled train model have been studied. Aspects of the discharge power consumption, the temperature distribution, the velocity of induced flow and the airflow field around the train model were considered. The applied AC voltage was set in the range of 20 kV to 28 kV, with a fixed frequency of 9 kHz. Results indicated that the discharge power consumption, the maximum temperature and the induced flow velocity increased with increasing applied voltage. Mechanisms of applied voltage influencing these key parameters were discussed from the point of the equivalent circuit. The airflow field around the train model with different applied voltages was observed by the smoke visualization experiment. Finally, the effects of surface dielectric barrier discharge on the train drag reduction with different applied voltages were analyzed.

  19. Wide-pressure-range coplanar dielectric barrier discharge: Operational characterisation of a versatile plasma source

    NASA Astrophysics Data System (ADS)

    Čech, J.; Bonaventura, Z.; SÅ¥ahel, P.; Zemánek, M.; Dvořáková, H.; Černák, M.

    2017-01-01

    Many plasma applications could benefit from the versatile plasma source operable at a wide-pressure-range, e.g., from the fraction of Pa to the super-atmospheric conditions. In this paper, the basic characteristics of wide-pressure-range plasma source based on the coplanar dielectric barrier discharge is given. The operational characteristics of this plasma source were measured in nitrogen at pressures ranging from 101 Pa (resp. 10-4 Pa) to 105 Pa. Measurements of the plasma geometry, breakdown voltage, and micro-discharges' behaviour revealed three operational regimes of this plasma source: "high pressure," "transitional" and "low-pressure" with vague boundaries at the pressures of approx. 10 kPa and 1 kPa. It was found that the plasma layer of coplanar dielectric barrier discharge could be expanded up to several centimetres to the half-space above the planar dielectric barrier when the gas pressure is reduced below 1 kPa, which provides an outstanding space to tailor the source for the specific applications. The proposed model of an effective gap distance in the Paschen breakdown criterion enabled us to explain the discharge behaviour fitting the experimental breakdown voltage data in the whole studied pressure range. Under the filament-forming conditions, i.e., at the pressure range from approx. 1-100 kPa, the active plasma volume could be varied through the micro-discharges' lateral thickness scaling with the inverse of the square-root of the gas pressure.

  20. Influence of the voltage polarity on the properties of a nanosecond surface barrier discharge in atmospheric-pressure air

    SciTech Connect

    Nudnova, M. M.; Aleksandrov, N. L.; Starikovskii, A. Yu.

    2010-01-15

    The properties of a surface barrier discharge in atmospheric-pressure air at different polarities of applied voltage were studied experimentally. The influence of the voltage polarity on the spatial structure of the discharge and the electric field in the discharge plasma was determined by means of spectroscopic measurements. It is found that the energy deposited in the discharge does not depend on the voltage polarity and that discharges of positive polarity are more homogenous and the electric fields in them are higher.

  1. Investigation of a single barrier discharge in submillimeter air gaps. Nonuniform field

    NASA Astrophysics Data System (ADS)

    Bondarenko, P. N.; Emel'yanov, O. A.; Shemet, M. V.

    2014-08-01

    Pulse characteristics of single barrier discharges as well as parameters of charges accumulated on the surface of a dielectric under the atmospheric pressure in the "needle-(0.1-2.0)-mm air gap-polymer barrier-plane" system are investigated. It is found experimentally that for the positive polarity of the needle, the voltage for the discharge initiation is higher than in the case of the negative polarity by ˜25-35%. The reversal of the needle polarity from negative to positive increases the amplitude of the discharge current and the accumulated surface charge by ˜1.5-3 times. For the positive polarity of the needle, the discharge is governed by a streamer mechanism, while for the negative polarity, the discharge is initiated by the formation of a single Trichel pulse. The single pulse regime is observed for the discharge current up to a certain electrode gap d CR. For the positive needle and for air gap width d air > d CR ≈ 1.5 mm, a multipulse burst corona is formed, while for the negative needle and d air > d CR ≈ 0.9 mm, a damped sequence of Trichel pulses evolves in the system.

  2. Formation of color centers in a thin layer of LiF crystals under VUV radiation from a barrier discharge

    NASA Astrophysics Data System (ADS)

    Milyutina, E. V.; Petrovskii, A. F.; Rakevich, A. L.; Martynovich, E. F.

    2014-05-01

    Under radiation from a barrier discharge, luminescent color centers are formed in a surface layer of lithium fluoride crystal served as a dielectric barrier. Analysis of the damping kinetics and luminescence spectra has revealed these centers to be F {3/+} and F 2 centers. Structural defects are mainly formed via the photon-induced mechanism (i.e., defects are formed due to the generation of electron-hole pairs as a result of absorption of photons of barrier-discharge radiation). Barrier discharge in different gases can be successfully used to form thin layers containing luminescence centers on the surface of transparent insulators for various scientific and practical applications.

  3. Motion of rotating pairs in a hexagonal superlattice pattern within dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Dong, Lifang; Li, Ben; Shen, Zhongkai; Wang, Yongjie; Lu, Ning

    2012-09-01

    Stochastic rotation of rotating pairs in a hexagonal superlattice pattern is observed in a dielectric barrier discharge system. It is found that the pairs rotate with orientation and diameter randomly changing by observing a series of frames recorded by a high speed video camera. Frames recorded by a high speed framing camera with an exposure time corresponding to current pulse phases in one half cycle of the applied voltage show that one rotating spot, six small spots, and another rotating spot in one cell discharge successively. Based on this discharging sequence, forces exerted on a rotating spot are analyzed at different discharging stages in a half voltage cycle. A resultant force on a rotating spot with both magnitude and direction varied leads to the stochastic rotation.

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

    NASA Astrophysics Data System (ADS)

    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.

  5. Motion of rotating pairs in a hexagonal superlattice pattern within dielectric barrier discharge.

    PubMed

    Dong, Lifang; Li, Ben; Shen, Zhongkai; Wang, Yongjie; Lu, Ning

    2012-09-01

    Stochastic rotation of rotating pairs in a hexagonal superlattice pattern is observed in a dielectric barrier discharge system. It is found that the pairs rotate with orientation and diameter randomly changing by observing a series of frames recorded by a high speed video camera. Frames recorded by a high speed framing camera with an exposure time corresponding to current pulse phases in one half cycle of the applied voltage show that one rotating spot, six small spots, and another rotating spot in one cell discharge successively. Based on this discharging sequence, forces exerted on a rotating spot are analyzed at different discharging stages in a half voltage cycle. A resultant force on a rotating spot with both magnitude and direction varied leads to the stochastic rotation.

  6. Investigation of nanosecond-pulsed dielectric barrier discharge actuators with powered electrodes of different exposures

    NASA Astrophysics Data System (ADS)

    Xu, Shuangyan; Cai, Jinsheng; Lian, Yongsheng

    2017-09-01

    Nanosecond-pulsed dielectric barrier discharge actuators with powered electrodes of different exposures were investigated numerically by using a newly proposed plasma kinetic model. The governing equations include the coupled continuity plasma discharge equation, drift-diffusion equation, electron energy equation, Poisson’s equation, and the Navier-Stokes equations. Powered electrodes of three different exposures were simulated to understand the effect of surface exposure on plasma discharge and surrounding flow field. Our study showed that the fully exposed powered electrode resulted in earlier reduced electric field breakdown and more intensive discharge characteristics than partially exposed and rounded-exposed ones. Our study also showed that the reduced electric field and heat release concentrated near the right upper tip of the powered electrode. The fully exposed electrode also led to stronger shock wave, higher heating temperature, and larger heated area.

  7. Spatio-temporal dynamics of the white-eye square superlattice pattern in dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Wei, Lingyan; Dong, Lifang; Feng, Jianyu; Liu, Weibo; Fan, Weili; Pan, Yuyang

    2016-05-01

    We report on the first investigation of the white-eye square superlattice pattern (WESSP) in a dielectric barrier discharge system. The evolution of patterns with increasing voltage is given. A phase diagram of WESSP as functions of gas pressure p and argon concentration φ is presented. The spatio-temporal dynamics of the WESSP is studied by using an intensified charge-coupled device camera and photomultipliers. Results show that the WESSP consists of four different transient sublattices, whose discharge sequence is small spots—spots on the line—halos—central spots in each half voltage cycle. The discharge moment and position of each sublattice are dependent upon the field of the wall charges produced by all sublattices discharged previously.

  8. Studies of the Electrohydrodynamic Force Produced in a Dielectric Barrier Discharge for Flow Control. Report no. 2, Phase 3

    DTIC Science & Technology

    2010-02-01

    AFRL-AFOSR-UK-TR-2010-0007 Studies of the Electrohydrodynamic Force Produced in a Dielectric Barrier Discharge for Flow Control...Final Report 3. DATES COVERED (From – To) 01 September 2006 - 01 September 2009 4. TITLE AND SUBTITLE Studies of the Electrohydrodynamic Force...surface dielectric barrier discharges (SDBDs) is identical to the one in corona discharges. The electrohydrodynamic force (EHD) generated in SDBDs for

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

    NASA Astrophysics Data System (ADS)

    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.

  10. Liposomal membrane disruption by means of miniaturized dielectric-barrier discharge in air: liposome characterization

    NASA Astrophysics Data System (ADS)

    Svarnas, P.; Asimakoulas, L.; Katsafadou, M.; Pachis, K.; Kostazos, N.; Antimisiaris, S. G.

    2017-08-01

    The increasing interest of the plasma community in the application of atmospheric-pressure cold plasmas to bio-specimen treatment has led to the creation of the emerging field of plasma biomedicine. Accordingly, plasma setups based on dielectric-barrier discharges have already been widely tested for the inactivation of various cells. Most of these systems refer to the plasma jet concept where noble gases penetrate atmospheric air and are subjected to the influence of high electric fields, thus forming guided streamers. Following the original works of our group where liposomal membranes were proposed as models for studying the interaction between plasma jets and cells, we present herein a study on liposomal membrane disruption by means of miniaturized dielectric-barrier discharge running in atmospheric air. Liposomal membranes of various lipid compositions, lamellarities, and sizes are treated at different times. It is shown that the dielectric-barrier discharge of low mean power leads to efficient liposomal membrane disruption. The latter is achieved in a controllable manner and depends on liposome properties. Additionally, it is clearly demonstrated that liposomal membrane disruption takes place even after plasma extinction, i.e. during post-treatment, resembling thus an ‘apoptosis’ effect, which is well known today mainly for cell membranes. Thus, the adoption of the present concept would be beneficial for tailoring studies on plasma-treated cell-mimics. Finally, the liposome treatment is discussed with respect to possible physicochemical mechanisms and potential discharge modification due to the various compositions of the liquid electrode.

  11. Controlled growth of aligned carbon nanotube using pulsed glow barrier discharge

    NASA Astrophysics Data System (ADS)

    Nozaki, Tomohiro; Kimura, Yoshihito; Okazaki, Ken

    2002-10-01

    We first achieved a catalytic growth of aligned carbon nanotube (CNT) using atmospheric pressure pulsed glow barrier discharge combined with DC bias (1000 V). Aligned CNT can grow with the directional electric field, and this is a big challenge in barrier discharges since dielectric barrier does not allow DC bias and forces to use AC voltage to maintain stable plasma conditions. To overcome this, we developed a power source generating Gaussian-shape pulses at 20 kpps with 4% duty, and DC bias was applied to the GND electrode where Ni-, Fe-coated substrate existed. With positive pulse, i.e. substrate was the cathode, random growth of CNT was observed at about 10^9 cm-2. Growth rate significantly reduced when applied negative pulse; Negative glow formation near substrate is essential for sufficient supply of radical species to the catalyst. If -DC was biased, aligned CNT with 20 nm was synthesized because negative bias enhanced negative glow formation. Interestingly, 2 to 3 CNTs stuck each other with +DC bias, resulting in 50-70 nm and non-aligned CNT. Atmospheric pressure glow barrier discharges can be highly controlled and be a potential alternative to vacuum plasmas for CVD, micro-scale, nano-scale fabrication.

  12. Numerical investigation of the spatiotemporal distribution of chemical species in an atmospheric surface barrier-discharge

    NASA Astrophysics Data System (ADS)

    Hasan, M. I.; Walsh, J. L.

    2016-05-01

    Using a one dimensional time dependent convection-reaction-diffusion model, the temporal and spatial distributions of species propagating downstream of an atmospheric pressure air surface barrier discharge was studied. It was found that the distribution of negatively charged species is more spatially spread compared to positive ions species, which is attributed to the diffusion of electrons that cool down and attach to background gas molecules, creating different negative ions downstream of the discharge region. Given the widespread use of such discharges in applications involving the remote microbial decontamination of surfaces and liquids, the transport of plasma generated reactive species away from the discharge region was studied by implementing mechanical convection through the discharge region. It was shown that increased convection causes the spatial distribution of species density to become uniform. It was also found that many species have a lower density close to the surface of the discharge as convection prevents their accumulation. While for some species, such as NO2, convection causes a general increase in the density due to a reduced residence time close to the discharge region, where it is rapidly lost through reactions with OH. The impact of the applied power was also investigated, and it was found that the densities of most species, whether charged or neutral, are directly proportional to the applied power.

  13. Numerical investigation of the spatiotemporal distribution of chemical species in an atmospheric surface barrier-discharge

    SciTech Connect

    Hasan, M. I.; Walsh, J. L.

    2016-05-28

    Using a one dimensional time dependent convection-reaction-diffusion model, the temporal and spatial distributions of species propagating downstream of an atmospheric pressure air surface barrier discharge was studied. It was found that the distribution of negatively charged species is more spatially spread compared to positive ions species, which is attributed to the diffusion of electrons that cool down and attach to background gas molecules, creating different negative ions downstream of the discharge region. Given the widespread use of such discharges in applications involving the remote microbial decontamination of surfaces and liquids, the transport of plasma generated reactive species away from the discharge region was studied by implementing mechanical convection through the discharge region. It was shown that increased convection causes the spatial distribution of species density to become uniform. It was also found that many species have a lower density close to the surface of the discharge as convection prevents their accumulation. While for some species, such as NO{sub 2}, convection causes a general increase in the density due to a reduced residence time close to the discharge region, where it is rapidly lost through reactions with OH. The impact of the applied power was also investigated, and it was found that the densities of most species, whether charged or neutral, are directly proportional to the applied power.

  14. Removal of several pesticides in a falling water film DBD reactor with activated carbon textile: Energy efficiency.

    PubMed

    Vanraes, Patrick; Ghodbane, Houria; Davister, Dries; Wardenier, Niels; Nikiforov, Anton; Verheust, Yannick P; Van Hulle, Stijn W H; Hamdaoui, Oualid; Vandamme, Jeroen; Van Durme, Jim; Surmont, Pieter; Lynen, Frederic; Leys, Christophe

    2017-03-06

    Bio-recalcitrant micropollutants are often insufficiently removed by modern wastewater treatment plants to meet the future demands worldwide. Therefore, several advanced oxidation techniques, including cold plasma technology, are being investigated as effective complementary water treatment methods. In order to permit industrial implementation, energy demand of these techniques needs to be minimized. To this end, we have developed an electrical discharge reactor where water treatment by dielectric barrier discharge (DBD) is combined with adsorption on activated carbon textile and additional ozonation. The reactor consists of a DBD plasma chamber, including the adsorptive textile, and an ozonation chamber, where the DBD generated plasma gas is bubbled. In the present paper, this reactor is further characterized and optimized in terms of its energy efficiency for removal of the five pesticides α-HCH, pentachlorobenzene, alachlor, diuron and isoproturon, with initial concentrations ranging between 22 and 430 μg/L. Energy efficiency of the reactor is found to increase significantly when initial micropollutant concentration is decreased, when duty cycle is decreased and when oxygen is used as feed gas as compared to air and argon. Overall reactor performance is improved as well by making it work in single-pass operation, where water is flowing through the system only once. The results are explained with insights found in literature and practical implications are discussed. For the used operational conditions and settings, α-HCH is the most persistent pesticide in the reactor, with a minimal achieved electrical energy per order of 8 kWh/m(3), while a most efficient removal of 3 kWh/m(3) or lower was reached for the four other pesticides.

  15. Wide Range Concentration Control of Dielectric Barrier Discharge Generated Ozone for Soil Sterilization

    NASA Astrophysics Data System (ADS)

    Ebihara, Kenji; Takayama, Masahiro; Strycewska, Henryka Danuta; Ikegami, Tomoaki; Gyoutoku, Yutaka; Tachibana, Masahiro

    We have developed ozone (O3) generation system suitable to soil sterilization. Wide range concentration control of O3 is required for the sterilization treatment depending on the soil property and plant growth. The dielectric barrier discharges using electrode such as Pyramid type is studied. Surface discharges are also applied to generate high concentration for quick sterilization of the agricultural soil. The treated soil properties under ozone sterilization were evaluated using pH and electrical conductivity. It is shown that ozone distribution in the soil is controlled mostly by the conditions such as concentration and flow rate as well as soil conditions of moisture and compositions.

  16. Shock Generation and Control Using DBD Plasma Actuators

    NASA Technical Reports Server (NTRS)

    Patel, Mehul P.; Cain, Alan B.; Nelson, Christopher C.; Corke, Thomas C.; Matlis, Eric H.

    2012-01-01

    This report is the final report of a NASA Phase I SBIR contract, with some revisions to remove company proprietary data. The Shock Boundary Layer Interaction (SBLI) phenomena in a supersonic inlet involve mutual interaction of oblique shocks with boundary layers, forcing the boundary layer to separate from the inlet wall. To improve the inlet efficiency, it is desired to prevent or delay shock-induced boundary layer separation. In this effort, Innovative Technology Applications Company (ITAC), LLC and the University of Notre Dame (UND) jointly investigated the use of dielectric-barrier-discharge (DBD) plasma actuators for control of SBLI in a supersonic inlet. The research investigated the potential for DBD plasma actuators to suppress flow separation caused by a shock in a turbulent boundary layer. The research involved both numerical and experimental investigations of plasma flow control for a few different SBLI configurations: (a) a 12 wedge flow test case at Mach 1.5 (numerical and experimental), (b) an impinging shock test case at Mach 1.5 using an airfoil as a shock generator (numerical and experimental), and (c) a Mach 2.0 nozzle flow case in a simulated 15 X 15 cm wind tunnel with a shock generator (numerical). Numerical studies were performed for all three test cases to examine the feasibility of plasma flow control concepts. These results were used to guide the wind tunnel experiments conducted on the Mach 1.5 12 degree wedge flow (case a) and the Mach 1.5 impinging shock test case (case b) which were at similar flow conditions as the corresponding numerical studies to obtain experimental evidence of plasma control effects for SBLI control. The experiments also generated data that were used in validating the numerical studies for the baseline cases (without plasma actuators). The experiments were conducted in a Mach 1.5 test section in the University of Notre Dame Hessert Laboratory. The simulation results from cases a and b indicated that multiple

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

    NASA Astrophysics Data System (ADS)

    Houba, Tomas

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

  18. Facilitators and Barriers of Heart Surgery Discharge: Patients' and Nurses' Narrative Accounts.

    PubMed

    Lapum, Jennifer L; Fredericks, Suzanne; Liu, Linda; Yau, Terrence M; Retta, Bruktawit; Jones, Vaska M; Hume, Sarah

    2016-01-01

    Optimal patient recovery from open-heart surgery relies on effective discharge planning and education. However, the nature of the discharge experience has not been clearly described. The study purpose is to explore patients' and nurses' narrative accounts of the facilitators and barriers of heart surgery discharge. A qualitative study was employed using a narrative methodology that elicited and analyzed stories. This research was conducted in a large, urban hospital in Ontario, Canada. A total of 17 patients and nurses were recruited. Five female and 5 male patients were recruited from a preoperative clinic. Ages ranged from 37 to 80 years. Seven nurses were recruited from inpatient cardiovascular units. They had 2 to 19 years of cardiovascular nursing experience. Semistructured, narrative-based interviews were conducted. Two interviews were conducted with each patient at 1 week after discharge and at 4 to 6 weeks. One interview was conducted with each nurse. Findings indicate that although the preoperative period was identified as an effective time for discharge preparation, the patient's cognitive capacity was limited during the postoperative phase of surgery. Both nurses and patients also found that insufficient time impeded the discharge process and limited individualized discussions. The structured and standardized delivery of discharge information affected patients' capacity to apply it to the particularities in their own lives and homes. The fostering of therapeutic relationships created a space where patients felt comfortable sharing their concerns and nurses learned more about patients and thus could better tailor the discharge approach. Study recommendations include group and scenario-based education in which patients and nurses brainstorm about how to apply the discharge information to the particularities of patients' lives and homes. Provision of support needs to be bolstered during the home period, where patients have timely opportunities to discuss

  19. Dissociation of nitrogen in a pulse-periodic dielectric barrier discharge at atmospheric pressure

    SciTech Connect

    Popov, N. A.

    2013-05-15

    Nitrogen molecule dissociation in a pulse-periodic atmospheric-pressure dielectric barrier discharge is numerically analyzed. It is shown that the quenching rate of predissociation states at atmospheric pressure is relatively low and the production of nitrogen atoms in this case can be adequately described using the cross section for electron-impact dissociation of N{sub 2} molecules taken from the paper by P.C. Cosby [J. Chem. Phys. 98, 9544 (1993)].

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

    NASA Astrophysics Data System (ADS)

    Nebogatkin, S. V.; Rebrov, I. E.; Khomich, V. Yu.; Yamshchikov, V. A.

    2016-01-01

    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.

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

    SciTech Connect

    Nebogatkin, S. V.; Rebrov, I. E.; Khomich, V. Yu.; Yamshchikov, V. A.

    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.

  2. Charge transfer in surface barrier discharge on μ sec to msec time scales

    NASA Astrophysics Data System (ADS)

    Leonov, Sergey; Adamovich, Igor; Petrishchev, Vitaly; OSU Team

    2014-10-01

    The paper presents experimental results characterizing dynamics of development and kinetics of energy coupling in surface dielectric barrier discharge (SDBD), sustained over dielectric and weakly conducting liquid surfaces, over a wide range of time scales and electrical conductivities. Time-resolved discharge development and mechanisms of coupling with quiescent air are analyzed using nanosecond gate camera imaging, high-sensitivity time-resolved schlieren imaging, surface charge sensor, and Laser Differential Interferometry. It is shown that NS SDBD plasmas generate high-amplitude, broadband, stochastic, point-wise, near-surface perturbations on a long time scale (>100 μs) after the discharge pulse. These perturbations are caused by discharge contraction and originate from the ends of individual streamers where they attach to the surface. It is also demonstrated a significant increase of energy (surface charge) stored on the dielectric surface during the NS discharge pulse, which in this case greatly exceeds energy dissipated as Joule heat (up to a few hundred percent). The present results strongly suggest that surface charge accumulation, along with use of alternating polarity pulse waveform, may significantly improve performance of surface discharge plasma actuators.

  3. Dynamic model based on voltage transfer curve for pattern formation in dielectric barrier glow discharge

    NASA Astrophysics Data System (ADS)

    Li, Ben; He, Feng; Duan, Xiaoxi; Ouyang, Jiting

    2015-12-01

    Simulation work is very important for understanding the formation of self-organized discharge patterns. Previous works have witnessed different models derived from other systems for simulation of discharge pattern, but most of these models are complicated and time-consuming. In this paper, we introduce a convenient phenomenological dynamic model based on the basic dynamic process of glow discharge and the voltage transfer curve (VTC) to study the dielectric barrier glow discharge (DBGD) pattern. VTC is an important characteristic of DBGD, which plots the change of wall voltage after a discharge as a function of the initial total gap voltage. In the modeling, the combined effect of the discharge conditions is included in VTC, and the activation-inhibition effect is expressed by a spatial interaction term. Besides, the model reduces the dimensionality of the system by just considering the integration effect of current flow. All these greatly facilitate the construction of this model. Numerical simulations turn out to be in good accordance with our previous fluid modeling and experimental result.

  4. Contraction of Surface Barrier Discharge at Positive and Negative Polarities in Atmospheric Air

    NASA Astrophysics Data System (ADS)

    Leonov, Sergey; Houpt, Alec

    2016-10-01

    This experimental study of surface dielectric barrier discharge examines the morphology and charge transfer dynamics depending on the supplied voltage pattern: single polarity vs alternating polarity. Diagnostics included electrical measurements, camera imaging, optical emission spectroscopy, and a set of original charge sensors. Two basic modes were analyzed: diffusive and filamentary. The key factor of the discharge dynamics is the development of ionization instability causing the contraction of the discharge current and formation of the filamentary, highly conductive plasma during both positive and negative polarities. A main criterion of the discharge contraction is the generation of a zone with a high level of longitudinal electric field, not less than 15 kV/cm, realized during the alternating of the sign of surface charge. It is shown that the alternating polarity of the supplied voltage accompanied with the process of discharge contraction gives a significant benefit in the surface area covered by the discharge and in the power deposition, increasing it 2-4 times. FlowPAC Institute, University of Notre Dame.

  5. Dynamic model based on voltage transfer curve for pattern formation in dielectric barrier glow discharge

    SciTech Connect

    Li, Ben; He, Feng; Ouyang, Jiting; Duan, Xiaoxi

    2015-12-15

    Simulation work is very important for understanding the formation of self-organized discharge patterns. Previous works have witnessed different models derived from other systems for simulation of discharge pattern, but most of these models are complicated and time-consuming. In this paper, we introduce a convenient phenomenological dynamic model based on the basic dynamic process of glow discharge and the voltage transfer curve (VTC) to study the dielectric barrier glow discharge (DBGD) pattern. VTC is an important characteristic of DBGD, which plots the change of wall voltage after a discharge as a function of the initial total gap voltage. In the modeling, the combined effect of the discharge conditions is included in VTC, and the activation-inhibition effect is expressed by a spatial interaction term. Besides, the model reduces the dimensionality of the system by just considering the integration effect of current flow. All these greatly facilitate the construction of this model. Numerical simulations turn out to be in good accordance with our previous fluid modeling and experimental result.

  6. Gas breakdown mechanism in pulse-modulated asymmetric ratio frequency dielectric barrier discharges

    NASA Astrophysics Data System (ADS)

    Wang, Qi; Sun, Jizhong; Nozaki, Tomohiro; Ding, Zhenfeng; Ding, Hongbin; Wang, Zhanhui; Wang, Dezhen

    2014-08-01

    The gas breakdown mechanisms, especially the roles of metastable species in atmospheric pressure pulse-modulated ratio frequency barrier discharges with co-axial cylindrical electrodes, were studied numerically using a one dimensional self-consistent fluid model. Simulation results showed that in low duty cycle cases, the electrons generated from the channels associated with metastable species played a more important role in initializing next breakdown than the direct ionization of helium atoms of electronic grounded states by electron-impact. In order to quantitatively evaluate the contribution to the discharge by the metastables, we defined a "characteristic time" and examined how the value varied with the gap distance and the electrode asymmetry. The results indicated that the lifetime of the metastable species (including He*and He2*) was much longer than that of the pulse-on period and as effective sources of producing electrons they lasted over a period up to millisecond. When the ratio of the outer radius to the inner radius of the cylindrical electrodes was far bigger than one, it was found that the metastables distributed mainly in a cylindrical region around the inner electrode. When the ratio decreased as the inner electrode moved outward, the density of metastables in the discharge region near the outer electrode became gradually noticeable. As the discharging gap continued to decrease, the two hill-shaped distributions gradually merged to one big hill. When the discharge spacing was fixed, asymmetric electrodes facilitated the discharge.

  7. Electrical and optical characteristics of the radio frequency surface dielectric barrier discharge plasma actuation

    NASA Astrophysics Data System (ADS)

    Wei-Long, Wang; Hui-Min, Song; Jun, Li; Min, Jia; Yun, Wu; Di, Jin

    2016-04-01

    Electrical characteristics and optical emission spectrum of the radio frequency (RF) surface dielectric barrier discharge (SDBD) plasma actuation are investigated experimentally in this paper. Influences of operating pressure, duty cycle and load power on the discharge are analyzed. When the operating pressure reaches 30 kPa, the discharge energy calculated from the Charge-Voltage (Q-V) Lissajous figure increases significantly, while the effective capacitance decreases remarkably. As the duty cycle of the applied voltage increases, the voltage-current waveforms, the area of Q-V loop and the capacity show no distinct changes. Below 40 W, effective capacitance increases with the increase of load power, but it almost remains unchanged when load power is between 40 W and 95 W. The relative intensity changes little as the operating pressure varies from 4 kPa to 100 kPa, while it rises evidently with the pressure below 4 kPa, which indicates that the RF discharge mode shifts from filamentary discharge to glow discharge at around 4 kPa. With the increase of load power, the relative intensity rises evidently. Additionally, the relative intensity is insensitive to the pressure, the duty cycle, and the load power. Project supported by the National Natural Science Foundation of China (Grant Nos. 11472306, 51276197, and 51336011).

  8. Optimization of a miniaturized DBD plasma chip for mercury detection in water samples.

    PubMed

    Abdul-Majeed, Wameath S; Parada, Jaime H Lozano; Zimmerman, William B

    2011-11-01

    In this work, an optimization study was conducted to investigate the performance of a custom-designed miniaturized dielectric barrier discharge (DBD) microplasma chip to be utilized as a radiation source for mercury determination in water samples. The experimental work was implemented by using experimental design, and the results were assessed by applying statistical techniques. The proposed DBD chip was designed and fabricated in a simple way by using a few microscope glass slides aligned together and held by a Perspex chip holder, which proved useful for miniaturization purposes. Argon gas at 75-180 mL/min was used in the experiments as a discharge gas, while AC power in the range 75-175 W at 38 kHz was supplied to the load from a custom-made power source. A UV-visible spectrometer was used, and the spectroscopic parameters were optimized thoroughly and applied in the later analysis. Plasma characteristics were determined theoretically by analysing the recorded spectroscopic data. The estimated electron temperature (T(e) = 0.849 eV) was found to be higher than the excitation temperature (T(exc) = 0.55 eV) and the rotational temperature (T(rot) = 0.064 eV), which indicates non-thermal plasma is generated in the proposed chip. Mercury cold vapour generation experiments were conducted according to experimental plan by examining four parameters (HCl and SnCl(2) concentrations, argon flow rate, and the applied power) and considering the recorded intensity for the mercury line (253.65 nm) as the objective function. Furthermore, an optimization technique and statistical approaches were applied to investigate the individual and interaction effects of the tested parameters on the system performance. The calculated analytical figures of merit (LOD = 2.8 μg/L and RSD = 3.5%) indicates a reasonable precision system to be adopted as a basis for a miniaturized portable device for mercury detection in water samples.

  9. Development of dielectric barrier discharge plasma processing apparatus for mass spectrometry and thin film deposition

    NASA Astrophysics Data System (ADS)

    Majumdar, Abhijit; Hippler, Rainer

    2007-07-01

    Cost effective and a very simple dielectric barrier discharge plasma processing apparatus for thin film deposition and mass spectroscopic analysis of organic gas mixture has been described. The interesting features of the apparatus are the construction of the dielectric electrodes made of aluminum oxide or alumina (Al2O3) and glass and the generation of high ignition voltage from the spark plug transformer taken from car. Metal capacitor is introduced in between ground and oscilloscope to measure the executing power during the discharge and the average electron density in the plasma region. The organic polymer films have been deposited on Si (100) substrate using several organic gas compositions. The experimental setup provides a unique drainage system from the reaction chamber controlled by a membrane pump to suck out and remove the poisonous gases or residuals (cyanogens, H-CN, CHxNH2, etc.) which have been produced during the discharge of CH4/N2 mixture.

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

    NASA Astrophysics Data System (ADS)

    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.

  11. Experimental and modelling study of organization phenomena in dielectric barrier discharges with structurally inhomogeneous wood substrates

    NASA Astrophysics Data System (ADS)

    Levasseur, O.; Profili, J.; Gangwar, R. K.; Naudé, N.; Clergereaux, R.; Gherardi, N.; Stafford, L.

    2014-10-01

    The spatial organization of dielectric barrier discharges operating at atmospheric pressure in the presence of complex wood substrates was analysed using optical imaging, current-voltage (I-V) characteristics, and optical emission spectroscopy combined with a collisional-radiative model to extract the average electron energy. The structural inhomogeneities of selected wood species produced non-uniform light emission patterns while maintaining homogeneous-like I-V characteristics and spatially uniform average electron energy. Based on a simple electrical model of the discharge, this localization was ascribed, at least partially, to a spatial modulation of the relative dielectric permittivity on ‘early’ versus ‘late’ wood affecting the local voltage applied to the gas, and thus the local discharge current.

  12. Methane activation using noble gases in a dielectric barrier discharge reactor

    SciTech Connect

    Jo, Sungkwon; Hoon Lee, Dae; Seok Kang, Woo; Song, Young-Hoon

    2013-08-15

    The conversion of methane is measured in a planar-type dielectric barrier discharge reactor using three different noble gases—He, Ne, and Ar—as additives. The empirical results obtained clearly indicate that methane activation is considerably affected by thy type of noble gas used. Through 0-D calculations, the discharge parameters inside the reactor, i.e., electron temperature and electron density, are estimated using experiment results. A comparison of the discharge characteristics and experimental results shows that the electron temperature is an important factor in achieving high methane activation and the mixture with Ar gas shows the highest methane conversion. These results are constructed using the mechanisms of energy and charge transfer from excited and ionized noble gas atoms to methane molecules, considering the number density of active atoms of noble gases. Finally, electron temperatures obtained for gas mixtures having different reactant compositions and concentrations are analyzed to estimate methane activation.

  13. Development of dielectric barrier discharge plasma processing apparatus for mass spectrometry and thin film deposition.

    PubMed

    Majumdar, Abhijit; Hippler, Rainer

    2007-07-01

    Cost effective and a very simple dielectric barrier discharge plasma processing apparatus for thin film deposition and mass spectroscopic analysis of organic gas mixture has been described. The interesting features of the apparatus are the construction of the dielectric electrodes made of aluminum oxide or alumina (Al(2)O(3)) and glass and the generation of high ignition voltage from the spark plug transformer taken from car. Metal capacitor is introduced in between ground and oscilloscope to measure the executing power during the discharge and the average electron density in the plasma region. The organic polymer films have been deposited on Si (100) substrate using several organic gas compositions. The experimental setup provides a unique drainage system from the reaction chamber controlled by a membrane pump to suck out and remove the poisonous gases or residuals (cyanogens, H-CN, CH(x)NH(2), etc.) which have been produced during the discharge of CH(4)N(2) mixture.

  14. Attenuation of single-tone ultrasound by an atmospheric glow discharge plasma barrier

    SciTech Connect

    Stepaniuk, Vadim P.; Ioppolo, Tindaro; Oetuegen, M. Volkan; Sheverev, Valery A.

    2010-09-15

    Propagation of 143 kHz ultrasound through an atmospheric pressure glow discharge in air was studied experimentally. The plasma was a continuous dc discharge formed by a multipin electrode system. Distributions of the gas temperature were also obtained in and around the plasma using laser-induced Rayleigh scattering technique. Results show significant attenuation of the ultrasound by the glow discharge plasma barrier (up to -24 dB). The results indicate that sound attenuation does not depend on the thickness of the plasma and attenuation is caused primarily by reflection of the sound waves from the plasma due to the sharp gas temperatures gradients that form at the plasma boundary. These gradients can be as high as 80 K/mm.

  15. Barriers to discharge in an acute care medical teaching unit: a qualitative analysis of health providers' perceptions.

    PubMed

    Okoniewska, Barbara; Santana, Maria Jose; Groshaus, Horacio; Stajkovic, Svetlana; Cowles, Jennifer; Chakrovorty, David; Ghali, William A

    2015-01-01

    The complex process of discharging patients from acute care to community care requires a multifaceted interaction between all health care providers and patients. Poor communication in a patient's discharge can result in post hospital adverse events, readmission, and mortality. Because of the gravity of these problems, discharge planning has been emphasized as a potential solution. The purpose of this paper is to identify communication barriers to effective discharge planning in an acute care unit of a tertiary care center and to suggest solutions to these barriers. Health care providers provided comments to a single open-ended question: "What are the communication barriers between the different health care providers that limit an effective discharge of patients from Unit 36?" We conducted qualitative thematic analysis by identifying themes related to communication barriers affecting a successful discharge process. Three broad themes related to barriers to the discharge process were identified: communication, lack of role clarity and lack of resources. We also identified two themes for opportunities for improvement, ie, structure and function of the medical team and need for leadership. While it was evident that poor communication was an overarching barrier identified by health care providers, other themes emerged. In an effort to increase inter-team communication, "bullet rounds", a condensed form of discharge rounds, were introduced to the medical teaching unit and occurred on a daily basis between the multidisciplinary team. To help facilitate provider-patient communication, electronic transfer of care summaries were suggested as a potential solution. To help role clarity, a discharge coordinator and/or liaison was suggested. Communication can be enhanced through use of electronic discharge summaries, bullet rounds, and implementation of a discharge coordinator(s). The findings from this study can be used to aid future researchers in devising appropriate

  16. Degradation of potential barriers in ZnO-based chip varistors due to electrostatic discharge

    NASA Astrophysics Data System (ADS)

    Hirose, Sakyo; Niimi, Hideaki; Kageyama, Keisuke; Ieki, Hideharu; Omata, Takahisa; Otsuka-Yao-Matsuo, Shinya

    2012-08-01

    Degradation of potential barriers in ZnO-based varistors due to the electrostatic discharge (ESD) was investigated using scanning probe microanalysis and capacitance-time and isothermal capacitance transient spectroscopies. Pr6O11-ZnO (Pr-ZnO) varistors exhibit excellent ESD withstand capability compared with Bi2O3-ZnO (Bi-ZnO) varistors. After the application of ESD, asymmetrically degraded double Schottky barriers were observed in both Pr-ZnO and Bi-ZnO varistors, and the Schottky barrier in Bi-ZnO was found to be destroyed. The potential barriers of both types of varistors can respond to an ESD pulse, whose rise time is ˜1 ns, but after application of the ESD pulse, the Bi-ZnO varistor takes more time to recover its initial capacitance than does the Pr-ZnO varistor. Such difference in the transient behaviors of potential barriers is attributed to differences in the energy and distribution of interfacial states of Pr-ZnO and Bi-ZnO varistors. Experimental results clearly indicated a strong correlation between the transient behaviors of potential barriers and the ESD withstand capabilities of ZnO-based varistors.

  17. Spectroscopic Diagnostics of Barrier Discharge Plasmas in Mixtures of Zinc Diiodide with Inert Gases

    SciTech Connect

    Guivan, N.N.; Malinin, A.N.

    2005-11-15

    The spectral characteristics of the emission of gas discharge atmospheric pressure plasmas in mixtures of zinc diiodide vapor with inert gases (He, Ne, Ar, Kr, and Xe) are investigated. The formation of a gas discharge plasma and the excitation of the components of a working mixture were performed in a high-frequency (with a repetition frequency of sinusoidal voltage pulses of 100 kHz) barrier discharge. The gas discharge emission was analyzed in the spectral range 200-900 nm with a resolution of 0.05 nm. Emission bands of ZnI(B-X) exciplex molecules and I*{sub 2} excimer molecules, lines of inert gases, and emission bands of XeI* exciplex molecules (in Xe-containing mixtures) were revealed. It is ascertained that the strongest emission of ZnI* molecules is observed in ZnI{sub 2}/He(Ne) mixtures. The regularities in the spectral characteristics of the gas discharge plasma emission are considered.

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

    NASA Astrophysics Data System (ADS)

    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.

  19. Physical and chemical properties of low-pressure argon-chlorine dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Barjasteh, Azadeh; Eslami, Esmaeil

    2016-03-01

    The influence of adding chlorine on the characteristics of a dielectric barrier discharge in Argon is investigated on the basis of a one-dimensional fluid model. The spatio-temporal characteristics of the discharge are obtained by applying a sinusoidal voltage with a frequency and amplitude of 7 kHz and 350 V, respectively. The study shows that the discharge has a homogeneous feature across the electrodes and has only one current pulse per half cycle of the applied voltage. The calculated electric field and electric potential as well as species number densities indicated that the discharge is in glow mode, and adding chlorine as electronegative gas up to 50% does not change its mode. It is observed that the most abundant negative species are C l - ions even in low additive chlorine. As a result, the maximum of plasma electronegativity takes place at 30% amounts of chlorine additive. The study of plasma radiations on the discharge gap shows that the main spontaneous emissions are observed at the wavelengths of 128.5 nm and 258 nm due to de-excitation of A r C l * and C l2 * molecules, respectively. Between different Ar/Cl2 mixtures, 0.99 A r - 0.01 C l 2 has the nearly uniform radiation in the positive column region.

  20. Comparison of the surface dielectric barrier discharge characteristics under different electrode gaps

    NASA Astrophysics Data System (ADS)

    Gao, Guoqiang; Dong, Lei; Peng, Kaisheng; Wei, Wenfu; Li, Chunmao; Wu, Guangning

    2017-01-01

    Currently, great interests are paid to the surface dielectric barrier discharge due to the diverse and interesting application. In this paper, the influences of the electrode gap on the discharge characteristics have been studied. Aspects of the electrical parameters, the optical emission, and the discharge induced gas flow were considered. The electrode gap varied from 0 mm to 21 mm, while the applied AC voltage was studied in the range of 17 kV-27 kV. Results indicate that with the increase of the electrode gap, the variation of discharge voltage exhibits an increasing trend, while the other parameters (i.e., the current, power, and induced flow velocity) increase first, and then decrease once the gap exceeded the critical value. Mechanisms of the electrode gap influencing these key parameters were discussed from the point of equivalent circuit. The experimental results reveal that an optimal discharge gap can be obtained, which is closely related to the applied voltage. Visualization of the induced flow with different electrode gaps was realized by the Schlieren diagnostic technique. Finally, the velocities of induced gas flow determined by the pitot tube were compared with the results of intensity-integral method, and good agreements were found.

  1. Influence of the Transverse Field Component on the Edge Effect in a Short-Gap Discharge

    NASA Astrophysics Data System (ADS)

    Ye, Qizheng; Yu, Dahai; Cai, Huanqing; Shao, Guiwei; Tan, Dan

    2013-11-01

    In a general plane-parallel electrode system, the edge of the electrode will undermine the uniformity of the dielectric barrier discharge (DBD) because of the influence of the distorted electrical field. In this paper, the influence of the non-uniform electrical field on the edge effect of DBDs in a short-gap is investigated. We present some of the experimental results of DBDs produced by three kinds of convex-spherical electrodes. The results show that there is a dark area (the homogeneous discharge) in the central region of the electrode and a bright halo (the filamentary discharge) in the outer peripheral region, and the radius of the dark region is determined by the electrode geometry. The calculated results of the transverse (radial) field component distribution on the surface of the electrodes show that the edge effect does not come from the electrode edge, but the transverse field. The discharge has enough space to be fully developed and then format the filamentary discharge in the outer peripheral region because the streamer of the filamentary discharge is driven to move along the direction of the longer path by the transverse field. Thus, the homogeneous discharge (the Townsend DBD or a glow DBD) could not be produced in this area.

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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