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

Science.gov (United States)

Sang, Chaofeng; Sun, Jizhong; Wang, Dezhen

2010-02-01

A particle-in-cell (PIC) plus Monte Carlo collision simulation is employed to investigate how a sustainable atmospheric pressure single dielectric-barrier discharge responds to a high-voltage nanosecond pulse (HVNP) further applied to the metal electrode. The results show that the HVNP can significantly increase the plasma density in the pulse-on period. The ion-induced secondary electrons can give rise to avalanche ionization in the positive sheath, which widens the discharge region and enhances the plasma density drastically. However, the plasma density stops increasing as the applied pulse lasts over certain time; therefore, lengthening the pulse duration alone cannot improve the discharge efficiency further. Physical reasons for these phenomena are then discussed.

Atomic oxygen production scaling in a nanosecond-pulsed externally grounded dielectric barrier plasma jet

Science.gov (United States)

Sands, Brian; Schmidt, Jacob; Ganguly, Biswa; Scofield, James

2014-10-01

Atomic oxygen production is studied in a capillary dielectric barrier plasma jet that is externally grounded and driven with a 20-ns risetime positive unipolar pulsed voltage at pulse repetition rates up to 25 kHz. The power coupled to the discharge can be easily increased by increasing the pulse repetition rate. At a critical turnover frequency, determined by the net energy density coupled to the discharge, the plasma chemistry abruptly changes. This is indicated by increased plasma conductance and a transition in reactive oxygen species production from an ozone-dominated production regime below the turnover frequency to atomic-oxygen-dominated production at higher pulse rates. Here, we characterize atomic oxygen production scaling using spatially- and temporally-resolved two-photon absorption laser-induced-fluorescence (TALIF). Quantitative results are obtained via calibration with xenon using a similar laser excitation and collection system. These results are compared with quantitative ozone and discharge power measurements using a helium gas flow with oxygen admixtures up to 3%.

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

Science.gov (United States)

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.

Comparison of high-voltage ac and pulsed operation of a surface dielectric barrier discharge

Science.gov (United States)

Williamson, James M.; Trump, Darryl D.; Bletzinger, Peter; Ganguly, Biswa N.

2006-10-01

A surface dielectric barrier discharge (DBD) in atmospheric pressure air was excited either by low frequency (0.3-2 kHz) high-voltage ac or by short, high-voltage pulses at repetition rates from 50 to 600 pulses s-1. The short-pulse excited discharge was more diffuse and did not have the pronounced bright multiple cathode spots observed in the ac excited discharge. The discharge voltage, current and average power deposited into the discharge were calculated for both types of excitation. As a measure of plasma-chemical efficiency, the ozone number density was measured by UV absorption as a function of average deposited power. The density of ozone produced by ac excitation did not increase so rapidly as that produced by short-pulse excitation as a function of average power, with a maximum measured density of ~3 × 1015 cm-3 at 25 W. The maximum ozone production achieved by short-pulse excitation was ~8.5 × 1015 cm-3 at 20 W, which was four times greater than that achieved by ac excitation at the same power level.

Characterization of a surface dielectric barrier discharge

NARCIS (Netherlands)

Pemen, A.J.M.; Beckers, F.J.C.M.; Heesch, van E.J.M.

2009-01-01

A surface dielectric barrier discharge (SDBD) reactor provides a homogeneous plasma over a large surface area. This allows surface treatments of foils, textiles or fibers. Here we present results of a study to characterize the AC and pulsed performance of SDBD with regard to ozone production,

Homogeneous dielectric barrier discharges in atmospheric air and its influencing factor

Science.gov (United States)

Ran, Junxia; Li, Caixia; Ma, Dong; Luo, Haiyun; Li, Xiaowei

2018-03-01

The stable homogeneous dielectric barrier discharge (DBD) is obtained in atmospheric 2-3 mm air gap. It is generated using center frequency 1 kHz high voltage power supply between two plane parallel electrodes with specific alumina ceramic plates as the dielectric barriers. The discharge characteristics are studied by a measurement of its electrical discharge parameters and observation of its light emission phenomena. The results show that a large single current pulse of about 200 μs duration appearing in each voltage pulse, and its light emission is radially homogeneous and covers the entire surface of the two electrodes. The homogeneous discharge generated is a Townsend discharge during discharge. The influences of applied barrier, its thickness, and surface roughness on the transition of discharge modes are studied. The results show that it is difficult to produce a homogeneous discharge using smooth plates or alumina plate surface roughness Ra material, dielectric thickness, and dielectric surface roughness should be used, and proper applied voltage amplitude and frequency should also be used.

Double discharges in unipolar-pulsed dielectric barrier discharge xenon excimer lamps

International Nuclear Information System (INIS)

Liu Shuhai; Neiger, Manfred

2003-01-01

Excitation of dielectric barrier discharge xenon excimer lamps by unipolar short square pulses is studied in this paper. Two discharges with different polarity are excited by each voltage pulse (double discharge phenomenon). The primary discharge occurs at the top or at the rising flank of the applied unipolar square pulse, which is directly energized by the external circuit. The secondary discharge with the reversed polarity occurs at the falling flank or shortly after the falling flank end (zero external voltage) depending on the pulse width, which is energized by the energy stored by memory charges deposited by the primary discharge. Fast-speed ICCD imaging shows the primary discharge has a conic discharge appearance with a channel broadening on the anode side. This channel broadening increases with increasing the pulse top level. Only the anode-side surface discharge is observed in the primary discharge. The surface discharge on the cathode side which is present in bipolar sine voltage excitation is not observed. On the contrary, the secondary discharge has only the cathode-side surface discharge. The surface discharge on the anode side is not observed. The secondary discharge is much more diffuse than the primary discharge. Time-resolved emission measurement of double discharges show the secondary discharge emits more VUV xenon excimer radiation but less infrared (IR) xenon atomic emission than the primary discharge. It was found that the IR xenon atomic emission from the secondary discharge can be reduced by shortening the pulse width. The energy efficiency of unipolar-pulsed xenon excimer lamps (the overall energy efficiency of double discharges) is much higher than that obtained under bipolar sine wave excitation. The output VUV spectrum under unipolar pulse excitation is found to be identical to that under sine wave excitation and independent of injected electric power

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

International Nuclear Information System (INIS)

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

2012-01-01

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 q max , and (iii) the development of a graphical method for the determination of q max from charge-voltage characteristics (Q-V plots, often referred as Lissajous figures) measured under pulsed excitation. The method of graphical presentation of q max is demonstrated with an example of a Q-V plot measured under pulsed excitation. The relations between the discharge current j R (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 C d . Whereas for quantitative evaluation of electrical measurements, the accurate estimation of the C d is important.

Comparison of high-voltage ac and pulsed operation of a surface dielectric barrier discharge

Energy Technology Data Exchange (ETDEWEB)

Williamson, James M [Innovative Scientific Solutions, Inc., 2766 Indian Ripple Road, Dayton, Ohio 45440-3638 (United States); Trump, Darryl D [Innovative Scientific Solutions, Inc., 2766 Indian Ripple Road, Dayton, Ohio 45440-3638 (United States); Bletzinger, Peter [Innovative Scientific Solutions, Inc., 2766 Indian Ripple Road, Dayton, Ohio 45440-3638 (United States); Ganguly, Biswa N [Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433-7919 (United States)

2006-10-21

A surface dielectric barrier discharge (DBD) in atmospheric pressure air was excited either by low frequency (0.3-2 kHz) high-voltage ac or by short, high-voltage pulses at repetition rates from 50 to 600 pulses s{sup -1}. The short-pulse excited discharge was more diffuse and did not have the pronounced bright multiple cathode spots observed in the ac excited discharge. The discharge voltage, current and average power deposited into the discharge were calculated for both types of excitation. As a measure of plasma-chemical efficiency, the ozone number density was measured by UV absorption as a function of average deposited power. The density of ozone produced by ac excitation did not increase so rapidly as that produced by short-pulse excitation as a function of average power, with a maximum measured density of {approx}3 x 10{sup 15} cm{sup -3} at 25 W. The maximum ozone production achieved by short-pulse excitation was {approx}8.5 x 10{sup 15} cm{sup -3} at 20 W, which was four times greater than that achieved by ac excitation at the same power level.

Comparison of high-voltage ac and pulsed operation of a surface dielectric barrier discharge

International Nuclear Information System (INIS)

Williamson, James M; Trump, Darryl D; Bletzinger, Peter; Ganguly, Biswa N

2006-01-01

A surface dielectric barrier discharge (DBD) in atmospheric pressure air was excited either by low frequency (0.3-2 kHz) high-voltage ac or by short, high-voltage pulses at repetition rates from 50 to 600 pulses s -1 . The short-pulse excited discharge was more diffuse and did not have the pronounced bright multiple cathode spots observed in the ac excited discharge. The discharge voltage, current and average power deposited into the discharge were calculated for both types of excitation. As a measure of plasma-chemical efficiency, the ozone number density was measured by UV absorption as a function of average deposited power. The density of ozone produced by ac excitation did not increase so rapidly as that produced by short-pulse excitation as a function of average power, with a maximum measured density of ∼3 x 10 15 cm -3 at 25 W. The maximum ozone production achieved by short-pulse excitation was ∼8.5 x 10 15 cm -3 at 20 W, which was four times greater than that achieved by ac excitation at the same power level

Effect of parallel magnetic field on repetitively unipolar nanosecond pulsed dielectric barrier discharge under different pulse repetition frequencies

Science.gov (United States)

Liu, Yidi; Yan, Huijie; Guo, Hongfei; Fan, Zhihui; Wang, Yuying; Wu, Yun; Ren, Chunsheng

2018-03-01

A magnetic field, with the direction parallel to the electric field, is applied to the repetitively unipolar positive nanosecond pulsed dielectric barrier discharge. The effect of the parallel magnetic field on the plasma generated between two parallel-plate electrodes in quiescent air is experimentally studied under different pulse repetition frequencies (PRFs). It is indicated that only the current pulse in the rising front of the voltage pulse occurs, and the value of the current is increased by the parallel magnetic field under different PRFs. The discharge uniformity is improved with the decrease in PRF, and this phenomenon is also observed in the discharge with the parallel magnetic field. By using the line-ratio technique of optical emission spectra, it is found that the average electron density and electron temperature under the considered PRFs are both increased when the parallel magnetic field is applied. The incremental degree of average electron density is basically the same under the considered PRFs, while the incremental degree of electron temperature under the higher-PRFs is larger than that under the lower-PRFs. All the above phenomena are explained by the effect of parallel magnetic field on diffusion and dissipation of electrons.

Numerical investigation of the effect of driving voltage pulse shapes on the characteristics of low-pressure argon dielectric barrier discharge

International Nuclear Information System (INIS)

Eslami, E.; Barjasteh, A.; Morshedian, N.

2015-01-01

In this work, we numerically compare the effect of a sinusoidal, triangular, and rectangular pulsed voltage profile on the calculated particle production, electric current, and gas voltage in a dielectric barrier discharge. The total argon gas pressure of 400 Pa, the distance between dielectrics of 5 mm, the dielectric thickness of 0.7 mm, and the temperature of T = 300 K were considered as input parameters. The different driving voltage pulse shapes (triangular, rectangular, and sinusoidal) are considered as applied voltage with a frequency of 7 kHz and an amplitude of 700 V peak to peak. It is shown that applying a rectangular voltage, as compared with a sinusoidal or triangle voltage, increases the current peak, while the peak width is decreased. Higher current density is related to high production of charged particles, which leads to the generation of some highly active species, such as Ar* (4s level), and Ar** (4p level) in the gap

Transient change in the shape of premixed burner flame with the superposition of pulsed dielectric barrier discharge

OpenAIRE

Zaima, Kazunori; Sasaki, Koichi

2016-01-01

We investigated the transient phenomena in a premixed burner flame with the superposition of a pulsed dielectric barrier discharge (DBD). The length of the flame was shortened by the superposition of DBD, indicating the activation of combustion chemical reactions with the help of the plasma. In addition, we observed the modulation of the top position of the unburned gas region and the formations of local minimums in the axial distribution of the optical emission intensity of OH. These experim...

Roughness modification of surfaces treated by a pulsed dielectric barrier discharge

CERN Document Server

Dumitrascu, N; Apetroaei, N; Popa, G

2002-01-01

Local modifications of surface roughness are very important in many applications, as this surface property is able to generate new mechano-physical characteristics of a large category of materials. Roughness is one of the most important parameters used to characterize and control the surface morphology, and techniques that allow modifying and controlling the surface roughness present increasing interest. In this respect we propose the dielectric barrier discharge (DBD) as a simple and low cost method that can be used to induce controlled roughness on various surfaces in the nanoscale range. DBD is produced in helium, at atmospheric pressure, by a pulsed high voltage, 28 kV peak to peak, 13.5 kHz frequency and 40 W power. This type of discharge is a source of energy capable of modifying the physico-chemical properties of the surfaces without affecting their bulk properties. The discharge is characterized by means of electrical probes and, in order to analyse the heat transfer rate from the discharge to the tre...

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

Science.gov (United States)

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.

Multiple current peaks in room-temperature atmospheric pressure homogenous dielectric barrier discharge plasma excited by high-voltage tunable nanosecond pulse in air

Energy Technology Data Exchange (ETDEWEB)

Yang, De-Zheng; Wang, Wen-Chun; Zhang, Shuai; Tang, Kai; Liu, Zhi-jie; Wang, Sen [Key Lab of Materials Modification, Dalian University of Technology, Ministry of Education, Dalian 116024 (China)

2013-05-13

Room temperature homogenous dielectric barrier discharge plasma with high instantaneous energy efficiency is acquired by using nanosecond pulse voltage with 20-200 ns tunable pulse width. Increasing the voltage pulse width can lead to the generation of regular and stable multiple current peaks in each discharge sequence. When the voltage pulse width is 200 ns, more than 5 organized current peaks can be observed under 26 kV peak voltage. Investigation also shows that the organized multiple current peaks only appear in homogenous discharge mode. When the discharge is filament mode, organized multiple current peaks are replaced by chaotic filament current peaks.

Ozone generation in a kHz-pulsed He-O2 capillary dielectric barrier discharge operated in ambient air

Science.gov (United States)

Sands, Brian L.; Ganguly, Biswa N.

2013-12-01

The generation of reactive oxygen species using nonequilibrium atmospheric pressure plasma jet devices has been a subject of recent interest due to their ability to generate localized concentrations from a compact source. To date, such studies with plasma jet devices have primarily utilized radio-frequency excitation. In this work, we characterize ozone generation in a kHz-pulsed capillary dielectric barrier discharge configuration comprised of an active discharge plasma jet operating in ambient air that is externally grounded. The plasma jet flow gas was composed of helium with an admixture of up to 5% oxygen. A unipolar voltage pulse train with a 20 ns pulse risetime was used to drive the discharge at repetition rates between 2-25 kHz. Using UVLED absorption spectroscopy centered at 255 nm near the Hartley-band absorption peak, ozone was detected over 1 cm from the capillary axis. We observed roughly linear scaling of ozone production with increasing pulse repetition rate up to a "turnover frequency," beyond which ozone production steadily dropped and discharge current and 777 nm O(5P→5S°) emission sharply increased. The turnover in ozone production occurred at higher pulse frequencies with increasing flow rate and decreasing applied voltage with a common energy density of 55 mJ/cm3 supplied to the discharge. The limiting energy density and peak ozone production both increased with increasing O2 admixture. The power dissipated in the discharge was obtained from circuit current and voltage measurements using a modified parallel plate dielectric barrier discharge circuit model and the volume-averaged ozone concentration was derived from a 2D ozone absorption measurement. From these measurements, the volume-averaged efficiency of ozone production was calculated to be 23 g/kWh at conditions for peak ozone production of 41 mg/h at 11 kV applied voltage, 3% O2, 2 l/min flow rate, and 13 kHz pulse repetition rate, with 1.79 W dissipated in the discharge.

Behaviour of atomic oxygen in a pulsed dielectric barrier discharge measured by laser-induced fluorescence

International Nuclear Information System (INIS)

Ono, Ryo; Yamashita, Youta; Takezawa, Kei; Oda, Tetsuji

2005-01-01

Atomic oxygen is measured in a pulsed dielectric barrier discharge (DBD) using two-photon absorption laser-induced fluorescence (TALIF). The ground-level atomic oxygen is excited to the 3p 3 P state by two-photon absorption at 226 nm. Negative (-40 kV) or positive (+30 kV) pulsed DBD occurs in an O 2 -N 2 mixture at atmospheric pressure. The pulse width of the DBD current is approximately 50 ns. The TALIF experiment shows that the decay rate of atomic oxygen increases linearly with O 2 concentration. This result proves that atomic oxygen decays mainly by the third-body reaction, O + O 2 + M → O 3 + M. The rate coefficient of the third-body reaction is estimated to be 2.2 x 10 -34 cm 6 s -1 in the negative DBD and 0.89 x 10 -34 cm 6 s -1 in the positive DBD. It is shown that the decay rate of atomic oxygen increases linearly with humidity. This can explain the well-known fact that ozone production in DBD is suppressed by increasing humidity

Transient change in the shape of premixed burner flame with the superposition of pulsed dielectric barrier discharge

Science.gov (United States)

Zaima, Kazunori; Sasaki, Koichi

2016-08-01

We investigated the transient phenomena in a premixed burner flame with the superposition of a pulsed dielectric barrier discharge (DBD). The length of the flame was shortened by the superposition of DBD, indicating the activation of combustion chemical reactions with the help of the plasma. In addition, we observed the modulation of the top position of the unburned gas region and the formations of local minimums in the axial distribution of the optical emission intensity of OH. These experimental results reveal the oscillation of the rates of combustion chemical reactions as a response to the activation by pulsed DBD. The cycle of the oscillation was 0.18-0.2 ms, which could be understood as the eigenfrequency of the plasma-assisted combustion reaction system.

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

Science.gov (United States)

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

2014-11-01

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

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

International Nuclear Information System (INIS)

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

2014-01-01

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

Investigation of the development of dielectric-barrier discharge instabilities in excimer lamp

Science.gov (United States)

Bouchachia, A.; Belasri, A.; Harrache, Z.; Amir Aid, D.

2017-11-01

This work represents a study of the formation and propagation of the streamer during a pulse in a plasma cell with dielectric barriers containing a Ne/Xe gas mixture. It is based on a longitudinal mono-dimensional model of the dielectric barrier discharge. In this model, we show the possibility of streamers development in the cathode sheath and its propagation during the plasma formation stage. The model gives the spatiotemporal variations of the propagation speed, the electric field, and the charged particle density of the streamer's head.

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

Science.gov (United States)

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.

Behaviour of atomic oxygen in a pulsed dielectric barrier discharge measured by laser-induced fluorescence

Energy Technology Data Exchange (ETDEWEB)

Ono, Ryo [High Temperature Plasma Center, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 227-8568 (Japan); Yamashita, Youta [Department of Electrical Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656 (Japan); Takezawa, Kei [Department of Electrical Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656 (Japan); Oda, Tetsuji [Department of Electrical Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656 (Japan)

2005-08-21

Atomic oxygen is measured in a pulsed dielectric barrier discharge (DBD) using two-photon absorption laser-induced fluorescence (TALIF). The ground-level atomic oxygen is excited to the 3p {sup 3}P state by two-photon absorption at 226 nm. Negative (-40 kV) or positive (+30 kV) pulsed DBD occurs in an O{sub 2}-N{sub 2} mixture at atmospheric pressure. The pulse width of the DBD current is approximately 50 ns. The TALIF experiment shows that the decay rate of atomic oxygen increases linearly with O{sub 2} concentration. This result proves that atomic oxygen decays mainly by the third-body reaction, O + O{sub 2} + M {yields} O{sub 3} + M. The rate coefficient of the third-body reaction is estimated to be 2.2 x 10{sup -34} cm{sup 6} s{sup -1} in the negative DBD and 0.89 x 10{sup -34} cm{sup 6} s{sup -1} in the positive DBD. It is shown that the decay rate of atomic oxygen increases linearly with humidity. This can explain the well-known fact that ozone production in DBD is suppressed by increasing humidity.

Influence of ion transport on discharge propagation of nanosecond dielectric barrier discharge plasma actuator

Science.gov (United States)

Hua, Weizhuo; Koji, Fukagata

2017-11-01

A numerical study has been conducted to understand the streamer formation and propagation of nanosecond pulsed surface dielectric barrier discharge of positive polarity. First we compared the result of different grid configuration to investigate the influence of x and y direction grid spacing on the streamer propagation. The streamer propagation is sensitive to y grid spacing especially at the dielectric surface. The streamer propagation velocity can reach 0.2 cm/ns when the voltage magnitude is 12 kV. A narrow gap was found between the streamer and dielectric barrier, where the plasma density is several orders of magnitude smaller than the streamer region. Analyses on the ion transport in the gap and streamer regions show the different ion transport mechanisms in the two different region. In the gap region, the diffusion of electron toward the dielectric layer decreases the seed electron in the beginning of voltage pulse, resulting that ionization avalanche does not occur. The streamer region is not significantly affected by the diffusion flux toward the dielectric layer, so that ionization avalanche takes place and leads to dramatic increase of plasma density.

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

International Nuclear Information System (INIS)

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

2016-01-01

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 × 10 4 m/s from anode to cathode in the simulated condition. The primary positive ion, negative ion, and excited species are O 2 + , O 3 − and O 2 ( 1 Δg) in pulsed DBD in air, respectively. N 2 O has the largest density among nitrogen oxides. e and N 2 + densities in the streamer head increase gradually to maximum values with the development of the streamer. Meanwhile, the O 2 + , O, O 3 , N 2 (A 3 Σ) and N 2 O densities reach maximum values in the vicinity of the anode. (paper)

Inactivation of Escherichia coli in water by pulsed dielectric barrier discharge in coaxial reactor.

Science.gov (United States)

Hernández-Arias, A N; Rodríguez-Méndez, B G; López-Callejas, R; Alcántara-Díaz, D; Valencia-Alvarado, R; Mercado-Cabrera, A; Peña-Eguiluz, R; Muñoz-Castro, A E; Barocio, S R; de la Piedad-Beneitez, A

2012-09-01

An experimental study of ATCC (American Type Culture Collection) 8739 Escherichia coli bacteria inactivation in water by means of pulsed dielectric barrier discharge (PDBD) atmospheric pressure plasmas is presented. Plasma is generated by an adjustable power source capable of supplying high voltage 25 kV pulses, ∼30 μs long and at a 500 Hz frequency. The process was conducted in a ∼152 cm(3) cylindrical stainless steel coaxial reactor, endowed with a straight central electrode and a gas inlet. The bacterial concentration in water was varied from 10(3) up to 10(8) E. coli cells per millilitre. The inactivation was achieved without gas flow in the order of 82% at 10(8) colony-forming units per millilitre (CFU mL(-1)) concentrations in 600 s. In addition, oxygen was added to the gas supply in order to increase the ozone content in the process, raising the inactivation percentage to the order of 90% in the same treatment time. In order to reach a higher efficiency however, oxygen injection modulation is applied, leading to inactivation percentages above 99.99%. These results are similarly valid for lower bacterial concentrations.

Improving the efficiency of a fluorescent Xe dielectric barrier light source using short pulse excitation

International Nuclear Information System (INIS)

Beleznai, Sz; Mihajlik, G; Richter, P; Maros, I; Balazs, L

2008-01-01

Operation of a Xe dielectric barrier discharge lamp producing 147-172 nm VUV radiation is investigated both theoretically and experimentally. Xe gas pressure varies between 100 and 300 mbar, and the glass body of the lamp is coated with LAP (green) phosphor to convert radiation into the visible part of the spectrum. Simulation results predict improved discharge efficiencies reaching 67% when excited by a fast rise-time, short pulse (∼200 ns) driving waveform. In this case most power deposited into the plasma efficiently produces Xe 2 * excimers, while other energy dissipation processes (ion heating, e-Xe elastic collision) are kept at a low rate. Simulation and experimental results are compared in terms of discharge efficacy and show good agreement. A lamp efficacy value as high as 80 lm W -1 is demonstrated experimentally

Statistical modelling of discharge behavior of atmospheric pressure dielectric barrier discharge

Energy Technology Data Exchange (ETDEWEB)

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

2014-11-15

In this work, stochastic behavior of atmospheric pressure dielectric barrier discharge (DBD) has been investigated. The experiment is performed in a DBD reactor consisting of a pair of stainless steel parallel plate electrodes powered by a 50 Hz ac high voltage source. Current pulse amplitude distributions for different space gaps and the time separation between consecutive current pulses are studied. A probability distribution function is proposed to predict the experimental distribution function for the current pulse amplitudes and the occurrence of the transition regime of the pulse distribution. Breakdown voltage at different positions on the dielectric surface is suggested to be stochastic in nature. The simulated results based on the proposed distribution function agreed well with the experimental results and able to predict the regime of transition voltage. This model would be useful for the understanding of stochastic behaviors of DBD and the design of DBD device for effective operation and applications.

Bacterial inactivation in water by means of a combined process of pulsed dielectric barrier discharge and silver-modified natural zeolite

International Nuclear Information System (INIS)

Rodríguez-Méndez, B G; López-Callejas, R; Olguín, M T; Valencia-Alvarado, R; Peña-Eguiluz, R; Mercado-Cabrera, A; Alcántara-Díaz, D; Muñoz-Castro, A E; Hernández-Arias, A N; De la Piedad-Beneitez, A

2014-01-01

We propose a novel combined system of pulsed dielectric barrier discharges (PDBDs) and silver-modified natural zeolite (Ag–zeolite) in liquid in bubbles. The system was tested with the Escherichia coli bacteria immersed in water. In order to evaluate the efficiency of the system in bacterial inactivation a microbiological analysis was carried out; 9.82-ln of bacterial reduction was obtained using the combined system, whereas 0.43-ln of bacterial reduction was obtained using Ag–zeolite alone, and 6.26-ln with PDBD. The elapsed time was 10 minutes for the three treatments. (paper)

Methods and Apparatus for Pulsed-DC Dielectric Barrier Discharge Plasma Actuator and Circuit

Science.gov (United States)

Corke, Thomas C. (Inventor); Kaszeta, Richard (Inventor); Gold, Calman (Inventor)

2017-01-01

A plasma generating device intended to induce a flow in a fluid via plasma generation includes a dielectric separating two electrodes and a power supply. The first electrode is exposed to a fluid flow while the second electrode is positioned under the dielectric. The power supply is electrically coupled to a switch and the first and second electrodes. When the power supply is energized by repeated action of the switch, it causes a pulsed DC current between the electrodes which causes the fluid to ionize generating a plasma. The generation of the plasma induces a force with a velocity component in the fluid.

Experimental investigation on the repetitively nanosecond pulsed dielectric barrier discharge with the parallel magnetic field

Science.gov (United States)

Liu, Yidi; Yan, Huijie; Guo, Hongfei; Fan, Zhihui; Wang, Yuying; Ren, Chunsheng

2018-02-01

The effects of a parallel magnetic field on the unipolar positive nanosecond pulsed dielectric barrier discharge are experimentally investigated through electrical and spectral measurements. The discharge is produced between two parallel-plate electrodes in the ambient air with a parallel magnetic field of 1.4 T. Experimental results show that both the discharge intensity and uniformity are improved in the discharge with the parallel magnetic field. The intensity ratio of the spectrum at 371.1 nm and 380.5 nm, which describes the average electron density, is increased by the parallel magnetic field. Meanwhile, the intensity ratio of the spectrum at 391.4 nm and 337.1 nm, which describes the electron temperature, is also increased. It is speculated that both the average electron density and the electron temperature are increased by the parallel magnetic field. The aforementioned phenomena have been explained by the confinement effect of the parallel magnetic field on the electrons.

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

Science.gov (United States)

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)

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

Science.gov (United States)

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.

Experimental investigation on NOx removal using pulsed dielectric barrier discharges in combination with catalysts

NARCIS (Netherlands)

Chirumamilla, V.R.; Hoeben, W.F.L.M.; Beckers, F.J.C.M.; Huiskamp, T.; Pemen, A.J.M.

2015-01-01

In this study, an experimental investigation of the removal of NOx has been carried out with a dielectric barrier discharge reactor filled with different catalytic materials. NOx removal efficiency and by-products formation were studied as a function of energy density using plasma catalytic

Electric field measurements in a dielectric barrier nanosecond pulse discharge with sub-nanosecond time resolution

International Nuclear Information System (INIS)

Goldberg, Benjamin M; Shkurenkov, Ivan; Adamovich, Igor V; Lempert, Walter R; O’Byrne, Sean

2015-01-01

The paper presents the results of time-resolved electric field measurements in a nanosecond discharge between two plane electrodes covered by dielectric plates, using picosecond four-wave mixing diagnostics. For absolute calibration, the IR signal was measured in hydrogen at a pressure of 440 Torr, for electrostatic electric field ranging from 0 to 8 kV cm −1 . The calibration curve (i.e. the square root of IR signal intensity versus electric field) was shown to be linear. By measuring the intensities of the pump, Stokes, and IR signal beam for each laser shot during the time sweep across the high-voltage pulse, temporal evolution of the electric field in the nanosecond pulse discharge was determined with sub-nanosecond time resolution. The results are compared to kinetic modeling predictions, showing good agreement, including non-zero electric field offset before the main high voltage pulse, breakdown moment, and reduction of electric field in the plasma after breakdown. The difference between the experimental results and model predictions is likely due to non-1D structure of the discharge. Comparison with the kinetic modeling predictions shows that electric field in the nanosecond pulse discharge is controlled primarily by electron impact excitation and charge accumulation on the dielectric surfaces. (paper)

Dielectric barrier discharge plasma actuator for flow control

Science.gov (United States)

Opaits, Dmitry Florievich

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

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

Directory of Open Access Journals (Sweden)

Mike Collier

2011-11-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2015-12-15

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

Multi-Chromatic Ultrashort Pulse Filamentation and Bulk Modification in Dielectrics

Science.gov (United States)

2016-05-05

AFRL-AFOSR-VA-TR-2016-0194 Multi- Chromatic Ultrashort Pulse Filamentation and Bulk Modification in Dielectrics Jeremy Gulley KENNESAW STATE...Jan 2016 4. TITLE AND SUBTITLE Multi- chromatic Ultrashort Pulse Filamentation and Bulk Modification in Dielectrics 5a. CONTRACT NUMBER 5b. GRANT...in, and modification of, dielectric solids by multi- chromatic ultrashort laser pulses. It was a theoretical effort to develop models of multi

Dielectric barrier discharges applied for soft ionization and their mechanism

Energy Technology Data Exchange (ETDEWEB)

Brandt, Sebastian; Klute, Felix David; Schütz, Alexander; Franzke, Joachim, E-mail: joachim.franzke@isas.de

2017-01-25

Dielectric barrier discharges are used for analytical applications as dissociative source for optical emission spectrometry and for ambient-ionization techniques. In the range of ambient-ionization techniques it has attracted much attention in fields like food safety, biological analysis, mass spectrometry for reaction monitoring and imaging forensic identification. In this review some examples are given for the application as desorption/ionization source as well as for the sole application as ionization source with different sample introductions. It will be shown that the detection might depend on the certain distance of the plasma in reference to the sample or the kind of discharge which might be produced by different shapes of the applied high voltage. Some attempts of characterization are presented. A more detailed characterization of the dielectric barrier discharge realized with two ring electrodes, each separately covered with a dielectric layer, is described. - Highlights: • Dielectric barrier discharge applied as desorption/ionization source. • Dielectric barrier discharge applied solely as ionization source. • Different geometries in order to maintain soft ionization. • Characterization of the LTP probe. • Dielectric barrier discharges with two dielectric barriers (ring-ring shape).

Ultrashort laser pulses and electromagnetic pulse generation in air and on dielectric surfaces

International Nuclear Information System (INIS)

Sprangle, P.; Penano, J.R.; Hafizi, B.; Kapetanakos, C.A.

2004-01-01

Intense, ultrashort laser pulses propagating in the atmosphere have been observed to emit sub-THz electromagnetic pulses (EMPS). The purpose of this paper is to analyze EMP generation from the interaction of ultrashort laser pulses with air and with dielectric surfaces and to determine the efficiency of conversion of laser energy to EMP energy. In our self-consistent model the laser pulse partially ionizes the medium, forms a plasma filament, and through the ponderomotive forces associated with the laser pulse, drives plasma currents which are the source of the EMP. The propagating laser pulse evolves under the influence of diffraction, Kerr focusing, plasma defocusing, and energy depletion due to electron collisions and ionization. Collective effects and recombination processes are also included in the model. The duration of the EMP in air, at a fixed point, is found to be a few hundred femtoseconds, i.e., on the order of the laser pulse duration plus the electron collision time. For steady state laser pulse propagation the flux of EMP energy is nonradiative and axially directed. Radiative EMP energy is present only for nonsteady state or transient laser pulse propagation. The analysis also considers the generation of EMP on the surface of a dielectric on which an ultrashort laser pulse is incident. For typical laser parameters, the power and energy conversion efficiency from laser radiation to EMP radiation in both air and from dielectric surfaces is found to be extremely small, -8 . Results of full-scale, self-consistent, numerical simulations of atmospheric and dielectric surface EMP generation are presented. A recent experiment on atmospheric EMP generation is also simulated

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

Science.gov (United States)

Liu, Chong; Dobrynin, Danil; Fridman, Alexander

2014-06-25

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.

Enhanced performance of an EUV light source (λ = 84 nm) using short-pulse excitation of a windowless dielectric barrier discharge in neon

International Nuclear Information System (INIS)

Carman, R J; Kane, D M; Ward, B K

2010-01-01

The electrical and optical characteristics of a dielectric barrier discharge (DBD) based neon excimer lamp generating output in the extreme ultraviolet (EUV) spectral range (λ = 84 nm) have been investigated experimentally. We report a detailed comparison of lamp performance for both pulsed and sinusoidal voltage excitation waveforms, using otherwise identical operating conditions. The results show that pulsed voltage excitation yields a ∼50% increase in the overall electrical to EUV conversion efficiency compared with sinusoidal waveforms, when operating in the pressure range 500-900 mbar. Pulsed operation allows greater control of parameters associated with the temporal evolution of the EUV pulse shapes (risetime, instantaneous peak power). The Ne DBD based source is also found to be highly monochromatic with respect to its spectral output from the second continuum band at λ ∼ 84 nm (5 nm FWHM). This continuum band dominates the spectral emission over the wavelength range 30-550 nm. Lamp performance; as measured by the overall EUV output energy, electrical to EUV conversion efficiency and spectral purity at λ ∼ 84 nm; improves with increasing gas pressure up to p = 900 mbar.

Theoretical research of multi-pulses laser induced damage in dielectrics

International Nuclear Information System (INIS)

Luo Jin; Liu Zhichao; Chen Songlin; Ma Ping

2013-01-01

The pulse width is different, the mechanism of the laser-matter interaction is different. Damage results from plasma formation and ablation forτ≤10 ps and from heat depositing and conventional melting for τ>100 ps. Two theoretical models of transparent dielectrics irradiated by multi-pulses laser are respectively developed based on the above-mentioned different mechanism. One is the dielectric breakdown model based on electron density evolution equation for femtosecond multi-pluses laser, the other is the dielectric heat-damage model based on Fourier's heat exchange equation for nanosecond multi-pluses laser. Using these models, the effects of laser parameters and material parameters on the laser-induced damage threshold of dielectrics are analyzed. The analysis results show that different parameters have different influence on the damage threshold. The effect of parameters on the multi -pulses damage threshold is not entirely the same to the single-pulse damage threshold. The multi-pulses damage mechanism of dielectrics is discussed in detail, considering the effect of different parameters. The discussion provides more information for understanding its damage process and more knowledge to improve its damage thresholds. And the relationship between damage threshold and pulse number is illustrated, it is in good agreement with experimental results. The illustration can help us to predict the multi-pulses damage threshold and the lifetime of optical components. (authors)

DC-pulse atmospheric-pressure plasma jet and dielectric barrier discharge surface treatments on fluorine-doped tin oxide for perovskite solar cell application

Science.gov (United States)

Tsai, Jui-Hsuan; Cheng, I.-Chun; Hsu, Cheng-Che; Chen, Jian-Zhang

2018-01-01

Nitrogen DC-pulse atmospheric-pressure plasma jet (APPJ) and nitrogen dielectric barrier discharge (DBD) were applied to pre-treat fluorine-doped tin oxide (FTO) glass substrates for perovskite solar cells (PSCs). Nitrogen DC-pulse APPJ treatment (substrate temperature: ~400 °C) for 10 s can effectively increase the wettability, whereas nitrogen DBD treatment (maximum substrate temperature: ~140 °C) achieved limited improvement in wettability even with increased treatment time of 60 s. XPS results indicate that 10 s APPJ, 60 s DBD, and 15 min UV-ozone treatment of FTO glass substrates can decontaminate the surface. A PSC fabricated on APPJ-treated FTO showed the highest power conversion efficiency (PCE) of 14.90%; by contrast, a PSC with nitrogen DBD-treated FTO shows slightly lower PCE of 12.57% which was comparable to that of a PSC on FTO treated by a 15 min UV-ozone process. Both nitrogen DC-pulse APPJ and nitrogen DBD can decontaminate FTO substrates and can be applied for the substrate cleaning step of PSC.

Contribution to the thermal study of a dielectric barrier discharge reactor

International Nuclear Information System (INIS)

Dubus, Nicolas

2009-01-01

This thesis aims to study the thermal behaviour of a laboratory Dielectric Barrier Discharge (DBD) reactor. An experimental study was first realized to measure temperatures at different points of the reactor by using optic fibers. These measurements were performed in transient and steady states. To examine the influence of heat losses, not insulated and insulated reactors were considered. The influence of the nature and the form of the applied voltage was else considered. Experiments were conducted with a sinusoidal voltage and a pulsed power supply. (author) [fr

Degradation of phenol using a combination of granular activated carbon adsorption and bipolar pulse dielectric barrier discharge plasma regeneration

Science.gov (United States)

Shoufeng, TANG; Na, LI; Jinbang, QI; Deling, YUAN; Jie, LI

2018-05-01

A combined method of granular activated carbon (GAC) adsorption and bipolar pulse dielectric barrier discharge (DBD) plasma regeneration was employed to degrade phenol in water. After being saturated with phenol, the GAC was filled into the DBD reactor driven by bipolar pulse power for regeneration under various operating parameters. The results showed that different peak voltages, air flow rates, and GAC content can affect phenol decomposition and its major degradation intermediates, such as catechol, hydroquinone, and benzoquinone. The higher voltage and air support were conducive to the removal of phenol, and the proper water moisture of the GAC was 20%. The amount of H2O2 on the GAC was quantitatively determined, and its laws of production were similar to phenol elimination. Under the optimized conditions, the elimination of phenol on the GAC was confirmed by Fourier transform infrared spectroscopy, and the total removal of organic carbons achieved 50.4%. Also, a possible degradation mechanism was proposed based on the HPLC analysis. Meanwhile, the regeneration efficiency of the GAC was improved with the discharge treatment time, which attained 88.5% after 100 min of DBD processing.

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

Science.gov (United States)

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2014-04-15

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

Investigation on discharge characteristics of a coaxial dielectric barrier discharge reactor driven by AC and ns power sources

Science.gov (United States)

Qian, WANG; Feng, LIU; Chuanrun, MIAO; Bing, YAN; Zhi, FANG

2018-03-01

A coaxial dielectric barrier discharge (DBD) reactor with double layer dielectric barriers has been developed for exhaust gas treatment and excited either by AC power or nanosecond (ns) pulse to generate atmospheric pressure plasma. The comparative study on the discharge characteristics of the discharge uniformity, power deposition, energy efficiency, and operation temperature between AC and ns pulsed coaxial DBD is carried out in terms of optical and electrical characteristics and operation temperature for optimizing the coaxial DBD reactor performance. The voltages across the air gap and dielectric layer and the conduction and displacement currents are extracted from the applied voltages and measured currents of AC and ns pulsed coaxial DBDs for the calculation of the power depositions and energy efficiencies through an equivalent electrical model. The discharge uniformity and operating temperature of the coaxial DBD reactor are monitored and analyzed by optical images and infrared camera. A heat conduction model is used to calculate the temperature of the internal quartz tube. It is found that the ns pulsed coaxial DBD has a much higher instantaneous power deposition in plasma, a lower total power consumption, and a higher energy efficiency compared with that excited by AC power and is more homogeneous and stable. The temperature of the outside wall of the AC and ns pulse excited coaxial DBD reaches 158 °C and 64.3 °C after 900 s operation, respectively. The experimental results on the comparison of the discharge characteristics of coaxial DBDs excited by different powers are significant for understanding of the mechanism of DBDs, reducing energy loss, and optimizing the performance of coaxial DBD in industrial applications.

Dielectric barrier discharge image processing by Photoshop

Science.gov (United States)

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.

Electrical and optical characteristics of dielectric-barrier discharge driven by high voltage nanosecond generator

International Nuclear Information System (INIS)

Ahmadeev, V.V.; Kost'yuchenko, S.V.; Kudryavtsev, N.N.; Kurkin, G.A.; Vasilyak, L.M.

1998-01-01

Electrical and optical characteristics of the dielectric-barrier discharge in the pressure range of 10-400 Torr were investigated experimentally, particular attention being paid to the discharge homogeneity and to the energy dissipation in the discharge volume. The discharge was driven by a high-voltage pulse generator producing nanosecond high-voltage pulses with an amplitude of 20-30 kV. Air, nitrogen, and helium were used as working gases. The discharge was found to be homogeneous within a wide range of gas pressure. A power density of up to 250 mW/cm 3 has been achieved. (J.U.)

Electrical response of relaxing dielectrics compressed by arbitrary stress pulses

International Nuclear Information System (INIS)

Lysne, P.C.

1983-01-01

The theoretical problem of the electric response of biased dielectrics and piezoelectrics subjected to planar stress pulse loading is considered. The materials are taken to exhibit dielectric relaxation in the sense that changes in the polarization induced by electric fields do not occur instantaneously with changes in the fields. While this paper considers arbitrary stress pulse loading of the specimen, examples that are amenable to projectile impact techniques are considered in detail. They are shock reverberation, thin pulse, and ramp loading experiments. It is anticipated that these experiments will play a role in investigations of dielectric relaxation caused by shock induced damage in insulators

Investigation of pulsed barrier discharge in water-air gap

International Nuclear Information System (INIS)

Taran, V.S.; Krasnyj, V.V.; Lozina, A.S.; Shvets, O.M.

2013-01-01

This article presents the results of the use of a pulsed dielectric barrier discharge with water electrode and diaphragm. The spectroscopic and electrical investigations of such discharge were conducted. The ozone concentration in an aqueous solution comprised 0.7 mg/l with high-voltage pulsed power at 120 W. The discharge reviewed emission spectrum lines of molecular nitrogen and hydroxyl radicals in the range of 200...800 nm in the water-air gap. The intensity changing of luminescence lines of OH and N 2 singles depending on the applied voltage and discharge gap has been determined. Aqueous solution of indigo was used in order to determine the impact level on the organic material. Experiments on inactivation of test E. coli cultures have been carried out.

Analysis of exhaust composition after purification in dielectric barrier discharges - Sub-project: Diesel exhaust purification in pulsed plasmas. Final report; Analyse der Abgaszusammensetzung bei Abgasreinigung in stillen Entladungen - Teilvorhaben: Reinigung von Dieselabgasen in gepulsten Plasmen. Abschlussbericht

Energy Technology Data Exchange (ETDEWEB)

NONE

2000-12-01

Diesel engine exhaust purification by dielectric barrier discharges was investigated with varied pulse generators and with a combination of dielectric barrier discharge and catalytic converters and diesel particulate filters. The detailed exhaused analysis served to describe the reactions in the systems and to detect the formation of new and potentially harmful exhaust components. [German] Die Anwendung einer dielektrisch behinderten Entladung zur Reinigung dieselmotorischen Abgases wurde untersucht. Die Wirkung der elektrischen Entladung auf das Abgas wurde durch Variation der verwendeten Pulsgeneratoren sowie durch Kombination der Entladung mit Katalysatoren und Diesel-Partikelfiltern beeinflusst. Die detaillierte Abgasanalyse ermoeglichte die Erklaerung der in den Systemen ablaufenden Reaktionen. Insbesondere diente sie dazu, die moegliche Bildung neuer, moeglicherweise unerwuenschter Abgaskomponenten zu erkennen. (orig.)

[Determination of electric field distribution in dielectric barrier surface glow discharge by spectroscopic method].

Science.gov (United States)

Li, Xue-chen; Jia, Peng-ying; Liu, Zhi-hui; Li, Li-chun; Dong, Li-fang

2008-12-01

In the present paper, stable glow discharges were obtained in air at low pressure with a dielectric barrier surface discharge device. Light emission from the discharge was detected by photomultiplier tubes and the research results show that the light signal exhibited one discharge pulse per half cycle of the applied voltage. The light pulses were asymmetric between the positive half cycle and the negative one of the applied voltage. The images of the glow surface discharge were processed by Photoshop software and the results indicate that the emission intensity remained almost constant for different places with the same distance from the powered electrode, while the emission intensity decreased with the distance from the powered electrode increasing. In dielectric barrier discharge, net electric field is determined by the applied voltage and the wall charges accumulated on the dielectric layer during the discharge, and consequently, it is important to obtain information about the net electric field distribution. For this purpose, optical emission spectroscopy method was used. The distribution of the net electric field can be deduced from the intensity ratio of spectral line 391.4 nm emitted from the first negative system of N2+ (B 2sigma u+ -->X 2sigma g+) to 337.1 nm emitted from the second positive system of N2 (C 3IIu-B 3IIg). The research results show that the electric field near the powered electric field is higher than at the edge of the discharge. These experimental results are very important for numerical study and industrial application of the surface discharge.

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

International Nuclear Information System (INIS)

Liu, Chong; Dobrynin, Danil; Fridman, Alexander

2014-01-01

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

Numerical study of the characteristics of a dielectric barrier discharge plasma actuator

Science.gov (United States)

Shi, C. A.; Adamiak, K.; Castle, G. S. P.

2018-03-01

A dielectric barrier discharge actuator to control airflow along a flat dielectric plate has been numerically investigated in this paper. In order to avoid large computing times, streamers, Trichel pulses and the ionic reactions involving photons and electrons are neglected. The numerical model assumes two types of generic ions, one positive and one negative, whose drift in the electric field produces the electrohydrodynamic flow. This study provides detailed insights into the physical mechanisms of DBD that include the electric field, space charge transport, surface charge accumulation and air flow motion. The results show the V-I characteristics, velocity profiles and drag force estimates. In addition, the effects of the voltage level, frequency and inlet air velocity on the actuator performance are presented and interpreted. The simulation results show a good agreement with theoretical expectations and experimental data available in literature.

Ozone Generation in Dry Air Using Pulsed Discharges With and Without a Solid Dielectric Layer

OpenAIRE

Samaranayake, W.J.M.; Miyahara, Y.; Namihira, T.; Katsuki, S.; Hackam, R.; Akiyama, H.; ミヤハラ, Y.; ナミヒラ, タカオ; カツキ, スナオ; アキヤマ, ヒデノリ; 浪平, 隆男; 勝木, 淳; 秋山, 秀典

2001-01-01

Energy efficient generation of ozone is very important because ozone is being used increasingly in a wide range of industrial applications. Ozonizers usually use dielectric barrier discharges and employ alternating current (ac) with consequent heat generation, which necessitates cooling. In the present study, very short duration pulsed voltage is employed resulting in reduced heating of the gas and discharge reactor. A comparison of ozone generation in dry air using a coaxial concentric elect...

Properties of dielectric barrier discharges in different arrangements

International Nuclear Information System (INIS)

Pietsch, G.J.

2001-01-01

Dielectric barrier discharges (DBDs) occur in arrangements where at least one dielectric is positioned in a gas space in between conducting electrodes. When breakdown field strength is reached in such a device, charge carriers are created in the gas region, accelerated, multiplied and finally collected on the surface(s) of the dielectric(s). The charge accumulation on the dielectric creates a counter field to that resulting from the power supply and as all of these processes are rather fast, the discharge quenches rapidly. The dielectric has two tasks, it limits the transferred charge and by this the energy conversion and distributes the discharge over the electrode area. That is why DBDs are non-thermal discharges which exist even at atmospheric pressure

Investigation of Vacuum Insulator Surface Dielectric Strength with Nanosecond Pulses

International Nuclear Information System (INIS)

Nunnally, W.C.; Krogh, M.; Williams, C.; Trimble, D.; Sampayan, S.; Caporaso, G.

2003-01-01

The maximum vacuum insulator surface dielectric strength determines the acceleration electric field gradient possible in a short pulse accelerator. Previous work has indicated that higher electric field strengths along the insulator-vacuum interface might be obtained as the pulse duration is decreased. In this work, a 250 kV, single ns wide impulse source was applied to small diameter, segmented insulators samples in a vacuum to evaluate the multi-layer surface dielectric strength of the sample construction. Resonances in the low inductance test geometry were used to obtain unipolar, pulsed electric fields in excess of 100 MV/m on the insulator surface. The sample construction, experimental arrangement and experimental results are presented for the initial data in this work. Modeling of the multi-layer structure is discussed and methods of improving insulator surface dielectric strength in a vacuum are proposed

Numerical investigation on the dynamics and evolution mechanisms of multiple-current-pulse behavior in homogeneous helium dielectric-barrier discharges at atmospheric pressure

Directory of Open Access Journals (Sweden)

Yuhui Zhang

2018-03-01

Full Text Available A systematic investigation on the dynamics and evolution mechanisms of multiple-current-pulse (MCP behavior in homogeneous dielectric barrier discharge (HDBD is carried out via fluid modelling. Inspecting the simulation results, two typical discharge regimes, namely the MCP-Townsend regime and MCP-glow regime, are found prevailing in MCP discharges, each with distinctive electrical and dynamic properties. Moreover, the evolution of MCP behavior with external parameters altering are illustrated and explicitly discussed. It is revealed that the discharge undergoes some different stages as external parameters vary, and the discharge in each stage follows a series of distinctive pattern in morphological characteristics and evolution trends. Among those stages, the pulse number per half cycle is perceived to observe non-monotonic variations with applied voltage amplitude (Vam and gap width (dg increasing, and a merging effect among pulses, mainly induced by the enhanced contribution of sinusoidal component to the total current, is considered responsible for such phenomenon. The variation of incipient discharge peak phase (Φpm is dominated by the value of Vam as well as the proportion of total applied voltage that drops across the gas gap. Moreover, an abnormal, dramatic elevation in Jpm with dg increasing is observed, which could be evinced by the strengthened glow discharge structure and therefore enhanced space charge effect.

Investigation on the influence of electrode geometry on characteristics of coaxial dielectric barrier discharge reactor driven by an oscillating microsecond pulsed power supply

Science.gov (United States)

Miao, Chuanrun; Liu, Feng; Wang, Qian; Cai, Meiling; Fang, Zhi

2018-03-01

In this paper, an oscillating microsecond pulsed power supply with rise time of several tens of nanosecond (ns) is used to excite a coaxial DBD with double layer dielectric barriers. The effects of various electrode geometries by changing the size of inner quartz tube (different electrode gaps) on the discharge uniformity, power deposition, energy efficiency, and operation temperature are investigated by electrical, optical, and temperature diagnostics. The electrical parameters of the coaxial DBD are obtained from the measured applied voltage and current using an equivalent electrical model. The energy efficiency and the power deposition in air gap of coaxial DBD with various electrode geometries are also obtained with the obtained electrical parameters, and the heat loss and operation temperature are analyzed by a heat conduction model. It is found that at the same applied voltage, with the increasing of the air gap, the discharge uniformity becomes worse and the discharge power deposition and the energy efficiency decrease. At 2.5 mm air gap and 24 kV applied voltage, the energy efficiency of the coaxial DBD reaches the maximum value of 68.4%, and the power deposition in air gap is 23.6 W and the discharge uniformity is the best at this case. The corresponding operation temperature of the coaxial DBD reaches 64.3 °C after 900 s operation and the temperature of the inner dielectric barrier is 114.4 °C under thermal balance. The experimental results provide important experimental references and are important to optimize the design and the performance of coaxial DBD reactor.

Calculation of Onset Voltage of Sliding Discharge over a Dielectric Barrier

Directory of Open Access Journals (Sweden)

Abdel-Salam Mazen

2016-01-01

Full Text Available This paper is aimed at calculating the onset voltage of a sliding discharge established between two electrodes at the upper and bottom surfaces of a dielectric barrier plate; named sliding dielectric barrier discharge (SDBD driven by AC voltage during negative half cycle. The onset voltage is based on the condition of self-sustenance of avalanche growth in the vicinity of the stressed electrode. This calls at first for calculation of the electric field in the vicinity of stressed electrode. The dependency of onset voltage on the thickness and permittivity of the dielectric barrier as well as the thickness of the stressed electrode and the inter-electrode spacing between the stressed and ground electrodes is investigated. The obtained results are discussed in the light of gas discharge physics.

On the regime transitions during the formation of an atmospheric pressure dielectric barrier glow discharge

International Nuclear Information System (INIS)

Martens, T; Bogaerts, A; Brok, W J M; Van Dijk, J

2009-01-01

The atmospheric pressure dielectric barrier discharge in helium is a pulsed discharge in nature. If during the electrical current pulse a glow discharge is reached, then this pulse will last only a few microseconds in operating periods of sinusoidal voltage with lengths of about 10 to 100 μs. In this paper we demonstrate that right before a glow discharge is reached, the discharge very closely resembles the commonly assumed Townsend discharge structure, but actually contains some significant differing features and hence should not be considered as a Townsend discharge. In order to clarify this, we present calculation results of high time and space resolution of the pulse formation. The results indicate that indeed a maximum of ionization is formed at the anode, but that the level of ionization remains high and that the electric field at that time is significantly disturbed. Our results also show where this intermediate structure comes from. (fast track communication)

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

Science.gov (United States)

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

2017-01-01

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

Post-breakdown secondary discharges at the electrode/dielectric interface of a cylindrical barrier discharge

Science.gov (United States)

Carman, Robert; Ward, Barry; Kane, Deborah

2011-10-01

The electrical breakdown characteristics of a double-walled cylindrical dielectric barrier discharge (DBD) lamp with a neon buffer gas under pulsed voltage excitation have been investigated. Following the formation of plasma in the main discharge gap, we have observed secondary breakdown phenomena at the inner and outer mesh electrode/dielectric interfaces under specific operating conditions. Plasma formation at these interfaces is investigated by monitoring the Ozone production rate in controlled flows of ultra high purity oxygen together with the overall electrical voltage-charge characteristics of the lamp. The results show that this secondary breakdown only occurs after the main discharge plasma has been established, and that significant electrical power may be dissipated in generating these spurious secondary plasmas. The results are important with regards to optimising the design and identifying efficient operating regimes of DBD based devices that employ mesh-type or wire/strip electrodes.

Dielectric barrier discharges applied for optical spectrometry

Czech Academy of Sciences Publication Activity Database

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

2016-01-01

Roč. 123, SEP (2016), s. 6-32 ISSN 0584-8547 R&D Projects: GA ČR GA14-23532S Institutional support: RVO:68081715 Keywords : dielectric barrier discharge * analytical spectroscopy * applications Subject RIV: CB - Analytical Chemistry , Separation Impact factor: 3.241, year: 2016

Dielectric barrier discharges applied for optical spectrometry

Czech Academy of Sciences Publication Activity Database

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

2016-01-01

Roč. 123, SEP (2016), s. 6-32 ISSN 0584-8547 R&D Projects: GA ČR GA14-23532S Institutional support: RVO:68081715 Keywords : dielectric barrier discharge * analytical spectroscopy * applications Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.241, year: 2016

Modeling short-pulse laser excitation of dielectric materials

DEFF Research Database (Denmark)

Wædegaard, Kristian Juncher; Sandkamm, Ditte Både; Haahr-Lillevang, Lasse

2014-01-01

A theoretical description of ultrashort-pulse laser excitation of dielectric materials based on strong-field excitation in the Keldysh picture combined with a multiple-rateequation model for the electronic excitation including collisional processes is presented. The model includes light attenuation...

High-efficiency dielectric barrier Xe discharge lamp: theoretical and experimental investigations

International Nuclear Information System (INIS)

Beleznai, Sz; Mihajlik, G; Agod, A; Maros, I; Juhasz, R; Nemeth, Zs; Jakab, L; Richter, P

2006-01-01

A dielectric barrier Xe discharge lamp producing vacuum-ultraviolet radiation with high efficiency was investigated theoretically and experimentally. The cylindrical glass body of the lamp is equipped with thin strips of metal electrodes applied to diametrically opposite sides of the outer surface. We performed a simulation of discharge plasma properties based on one-dimensional fluid dynamics and also assessed the lamp characteristics experimentally. Simulation and experimental results are analysed and compared in terms of voltage and current characteristics, power input and discharge efficiency. Using the proposed lamp geometry and fast rise-time short square pulses of the driving voltage, an intrinsic discharge efficiency around 56% was predicted by simulation, and more than 60 lm W -1 lamp efficacy (for radiation converted into visible green light by phosphor coating) was demonstrated experimentally

Evaluation of Dielectric-Barrier-Discharge Actuator Substrate Materials

Science.gov (United States)

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

2014-01-01

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

Cathode fall measurement in a dielectric barrier discharge in helium

Energy Technology Data Exchange (ETDEWEB)

Hao, Yanpeng; Zheng, Bin; Liu, Yaoge [School of Electric Power, South China University of Technology, Guangzhou 510640 (China)

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.

Ozone production in a dielectric barrier discharge with ultrasonic irradiation

DEFF Research Database (Denmark)

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

2011-01-01

Ozone production has been investigated using an atmospheric pressure dielectric barrier discharge in pure O2 at room temperature with and without ultrasonic irradiation. It was driven at a frequency of either 15 kHz or 40 kHz. The ozone production was highly dependent on the O2 flow rate and the ......Ozone production has been investigated using an atmospheric pressure dielectric barrier discharge in pure O2 at room temperature with and without ultrasonic irradiation. It was driven at a frequency of either 15 kHz or 40 kHz. The ozone production was highly dependent on the O2 flow rate...

Ozone Production With Dielectric Barrier Discharge: Effects of Power Source and Humidity

KAUST Repository

Zhang, Xuming

2016-08-24

Ozone synthesis in air dielectric barrier discharge (DBD) was studied with an emphasis on the effects of power sources and humidity. Discharge characteristics were investigated to understand the physical properties of plasma and corresponding system performance. It was found that 10-ns pulsed DBD produced a homogeneous discharge mode, while ac DBD yielded an inhomogeneous pattern with many microdischarge channels. At a similar level of the energy density (ED), decreasing the flowrate is more effective in the production of ozone for the cases of the ac DBD, while increased voltage is more effective for the pulsed DBD. Note that the maximum ozone production efficiency (110 g/kWh) was achieved with the pulsed DBD. At the ED of ∼ 85 J/L, the ozone concentrations with dry air were over three times higher than those with the relative humidity of 100% for both the ac DBD and pulsed DBD cases. A numerical simulation was conducted using a global model to understand a detailed chemical role of water vapor to ozone production. It was found HO and OH radicals from water vapor significantly consumed O atoms, resulting in a reduction in ozone production. The global model qualitatively captured the experimental trends, providing further evidence that the primary effect of humidity on ozone production is chemical in nature.

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

Science.gov (United States)

2014-10-28

results for MIG with the US3D code devel- oped at the University of Minnesota.61 US3D is an unstruc- tured CFD code for hypersonic flow solution used...Effect of dielectric barrier discharge plasma actuators on non-equilibrium hypersonic flows Ankush Bhatia,1 Subrata Roy,1 and Ryan Gosse2 1Applied...a cylindrical body in Mach 17 hypersonic flow is presented. This application focuses on using sinusoidal dielectric barrier discharge plasma actuators

Two-Dimensional Simulation of Spatial-Temporal Behaviors About Period Doubling Bifurcation in an Atmospheric-Pressure Dielectric Barrier Discharge

International Nuclear Information System (INIS)

Zhang Jiao; Wang Yanhui; Wang Dezhen; Zhuang Juan

2014-01-01

As a spatially extended dissipated system, atmospheric-pressure dielectric barrier discharges (DBDs) could in principle possess complex nonlinear behaviors. In order to improve the stability and uniformity of atmospheric-pressure dielectric barrier discharges, studies on temporal behaviors and radial structure of discharges with strong nonlinear behaviors under different controlling parameters are much desirable. In this paper, a two-dimensional fluid model is developed to simulate the radial discharge structure of period-doubling bifurcation, chaos, and inverse period-doubling bifurcation in an atmospheric-pressure DBD. The results show that the period-2n (n = 1, 2…) and chaotic discharges exhibit nonuniform discharge structure. In period-2n or chaos, not only the shape of current pulses doesn't remains exactly the same from one cycle to another, but also the radial structures, such as discharge spatial evolution process and the strongest breakdown region, are different in each neighboring discharge event. Current-voltage characteristics of the discharge system are studied for further understanding of the radial structure. (low temperature plasma)

Electrical and kinetical aspects of homogeneous dielectric-barrier discharge in xenon for excimer lamps

International Nuclear Information System (INIS)

Belasri, A.; Harrache, Z.

2010-01-01

A pulsed dielectric-barrier discharge in xenon has been simulated for operating conditions typical to excimer lamps, in which the discharge is considered spatially homogeneous. The computer model developed is based on the xenon plasma chemistry, the circuit, and the Boltzmann equations. First, the validity of the physical model was checked and compared to experimental and theoretical works, and then the model is applied in the case of a sinusoidal voltage at period frequencies in the range of 50 kHz-2 MHz. The results obtained with the present description are in good agreement with experimental measurements and one-dimensional fluid prediction in terms of electrical characteristics and vacuum ultraviolet (vuv) emission. The effect of operation voltage, power source frequency, dielectric capacitance, as well as gas pressure on the discharge efficiency and the 172, 150, and 147 nm photon generation, under the typical experimental operating conditions and for the case of a sinusoidal applied voltage, have been investigated and discussed. Calculations suggest that the overall conversion efficiency from electrical energy to vuv emission in the lamp is greater than 38%, and it will be very affected at high power source frequency and high gas pressure with a significant dependence on the dielectric capacitance.

Developments of ozone generation using dielectric barrier discharge at the Universidad del Valle

OpenAIRE

Echeverry-Ibarra, Diego F.

2013-01-01

This paper presents the research results related to ozone technology using dielectric barrier discharge DBD, obtained at the Universidad del Valle. Particular emphasis is placed on increasing efficiency, the modeling of the surface dielectric barrier discharge generator and the control technique which modifies the relation production vs. efficiency of the generators. Finally, the ozone applications worked at the university are presented. The current state of these developments is promising fo...

Dynamics of dielectric barrier discharges in coplanar arrangements

International Nuclear Information System (INIS)

Gibalov, Valentin I; Pietsch, Gerhard J

2004-01-01

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

Appearance of a conductive carbonaceous coating in a CO2 dielectric barrier discharge and its influence on the electrical properties and the conversion efficiency

International Nuclear Information System (INIS)

Belov, Igor; Paulussen, Sabine; Bogaerts, Annemie

2016-01-01

This work examines the properties of a dielectric barrier discharge (DBD) reactor, built for CO 2 decomposition, by means of electrical characterization, optical emission spectroscopy and gas chromatography. The discharge, formed in an electronegative gas (such as CO 2 , but also O 2 ), exhibits clearly different electrical characteristics, depending on the surface conductivity of the reactor walls. An asymmetric current waveform is observed in the metal-dielectric (MD) configuration, with sparse high-current pulses in the positive half-cycle (HC) and a more uniform regime in the negative HC. This indicates that the discharge is operating in two alternating regimes with rather different properties. At high CO 2 conversion regimes, a conductive coating is deposited on the dielectric. This so-called coated MD configuration yields a symmetric current waveform, with current peaks in both the positive and negative HCs. In a double-dielectric (DD) configuration, the current waveform is also symmetric, but without current peaks in both the positive and negative HC. Finally, the DD configuration with conductive coating on the inner surface of the outer dielectric, i.e. so-called coated DD, yields again an asymmetric current waveform, with current peaks in the negative HC. These different electrical characteristics are related to the presence of the conductive coating on the dielectric wall of the reactor and can be explained by an increase of the local barrier capacitance available for charge transfer. The different discharge regimes affect the CO 2 conversion, more specifically, the CO 2 conversion is lowest in the clean DD configuration. It is somewhat higher in the coated DD configuration, and still higher in the MD configuration. The clean and coated MD configuration, however, gave similar CO 2 conversion. These results indicate that the conductivity of the dielectric reactor walls can highly promote the development of the high-amplitude discharge current pulses and

Pulsed sub-microsecond dielectric barrier discharge treatment of simulated glass manufacturing industry flue gas: removal of SO2 and NOx

International Nuclear Information System (INIS)

Khacef, A; Cormier, J M

2006-01-01

Experiments were carried out to investigate the removal of SO 2 and NOx from simulated glass manufacturing industry flue gas containing O 2 , N 2 , NO, NO 2 , CO 2 , SO 2 and H 2 O using a sub-microsecond pulsed dielectric barrier discharge (DBD) at atmospheric pressure. Removal efficiencies of SO 2 and NOx (NO+NO 2 ) were achieved as a function of gas temperature for two specific energies and two initial NO, NO 2 and SO 2 concentrations. The higher SO 2 and NOx removal efficiencies were achieved in a gas stream containing 163 ppm of SO 2 , 523 ppm of NO, 49 ppm of NO 2 , 14% of CO 2 , 8% of O 2 , 16% of H 2 O and N 2 as balance. The experimental results were evaluated using the energy cost or W-value (eV/molecule removed). About 100% of SO 2 and 36% of NOx were removed at a gas temperature of 100 deg. C with an energy cost of about 45 eV/molecule removed and 36 eV/molecule removed, respectively. These results indicate that DBD plasmas have the potential to remove SO 2 and NOx from gas streams without additives

Three cell flying capacitor inverter for dielectric barrier discharge plasma applications

International Nuclear Information System (INIS)

Flores-Fuentes, A.; Lopez-Callejas, A.; Piedad-Beneitez, A. de la; Pena-Eguiluz, R.; Mercado-Cabrera, A.; Valencia-Alvarado, R.; Barocio, S.R.

2009-01-01

It is reported the design, construction and initial tests of a three cell flying capacitor inverter (TCFCI) in a half-bridge configuration. The device operates at a 200 k Hz frequency which leads to a voltage output at 12.5 k Hz presenting an acceptable response in an open-loop configuration. These features outdo those reported in the current multilevel converter literature. The TCFCI is driven by pulse width modulation, following a phase shift (PS-PWM) control strategy, in order to generate a steady AC voltage signal. This inverter is used to excite a dielectric barrier discharge cell (DBDC) intended for cold plasma generation at room pressure. Some results obtained for two different kinds of atmosphere, helium and argon, are presented. All the system having been tested, early recorded voltage and current waveforms, are included. Finally, three methods for calculating the related electric efficiency of the discharge cell are discussed. (author)

Ultrashort-pulse laser excitation and damage of dielectric materials

DEFF Research Database (Denmark)

Haahr-Lillevang, Lasse; Balling, Peter

2015-01-01

Ultrashort-pulse laser excitation of dielectrics is an intricate problem due to the strong coupling between the rapidly changing material properties and the light. In the present paper, details of a model based on a multiple-rate-equation description of the conduction band are provided. The model...

Influence of grid resolution in fluid-model simulation of nanosecond dielectric barrier discharge plasma actuator

Science.gov (United States)

Hua, Weizhuo; Fukagata, Koji

2018-04-01

Two-dimensional numerical simulation of a surface dielectric barrier discharge (SDBD) plasma actuator, driven by a nanosecond voltage pulse, is conducted. A special focus is laid upon the influence of grid resolution on the computational result. It is found that the computational result is not very sensitive to the streamwise grid spacing, whereas the wall-normal grid spacing has a critical influence. In particular, the computed propagation velocity changes discontinuously around the wall-normal grid spacing about 2 μm due to a qualitative change of discharge structure. The present result suggests that a computational grid finer than that was used in most of previous studies is required to correctly capture the structure and dynamics of streamer: when a positive nanosecond voltage pulse is applied to the upper electrode, a streamer forms in the vicinity of upper electrode and propagates along the dielectric surface with a maximum propagation velocity of 2 × 108 cm/s, and a gap with low electron and ion density (i.e., plasma sheath) exists between the streamer and dielectric surface. Difference between the results obtained using the finer and the coarser grid is discussed in detail in terms of the electron transport at a position near the surface. When the finer grid is used, the low electron density near the surface is caused by the absence of ionization avalanche: in that region, the electrons generated by ionization is compensated by drift-diffusion flux. In contrast, when the coarser grid is used, underestimated drift-diffusion flux cannot compensate the electrons generated by ionization, and it leads to an incorrect increase of electron density.

Effect of voltage waveform on dielectric barrier discharge ozone production efficiency

Science.gov (United States)

Mericam-Bourdet, N.; Kirkpatrick, M. J.; Tuvache, F.; Frochot, D.; Odic, E.

2012-03-01

Dielectric barrier discharges (DBDs) are commonly used for gas effluent cleanup and ozone generation. For these applications, the energy efficiency of the discharge is a major concern. This paper reports on investigations carried out on the voltage shape applied to DBD reactor electrodes, aiming to evaluate a possible energy efficiency improvement for ozone production. Two DBD reactor geometries were used: pin-to-pin and cylinder-to-cylinder, both driven either by a bi-directional power supply (voltage rise rate 1 kV/μs) or by a pulsed power supply (voltage rise rate 1 kV/ns). Ozone formed in dry air was measured at the reactor outlet. Special attention was paid to discharge input power evaluation using different methods including instantaneous current-voltage product and transferred charge-applied voltage figures. The charge transferred by the discharges was also correlated to the ozone production. It is shown that, in the case of the DBD reactors under investigation, the applied voltage shape has no influence on the ozone production efficiency. For the considered voltage rise rate, the charge deposit on the dielectric inserted inside the discharge gap is the important factor (as opposed to the voltage shape) governing the efficiency of the discharge - it does this by tailoring the duration of the current peak into the tens of nanosecond range.

Electrical characterization of microdischarges produced by dielectric barrier discharge in dry air at atmospheric pressure

International Nuclear Information System (INIS)

Jidenko, N; Petit, M; Borra, J P

2006-01-01

This work addresses the case of millimetre sized plane-to-plane dielectric barrier discharge with sinusoidal voltage between 1 and 60 kHz for different configurations in air at atmospheric pressure. The first aim of this work is to achieve a representative statistical analysis of the electrical characteristics of the microdischarges. The numerical data treatment presented here enables us to determine the maximum current, the duration, the amount of charge and the triggering voltage for each current pulse. Both the average values as well as the deviations are checked. The relative influence of the operating parameters (voltage, gas flow rate, gap width, frequency) on the local surface polarization, electron attachment and temperature affecting microdischarge characteristics has been depicted in different arrangements. A special attention is paid to the influence of dielectric walls inside the discharge gap, perpendicular to the electrodes. Besides, this study allows the identification of the operating conditions for which all the microdischarges can be considered identical to study the local physical and chemical processes around each microdischarge

Electrical characterization of microdischarges produced by dielectric barrier discharge in dry air at atmospheric pressure

Energy Technology Data Exchange (ETDEWEB)

Jidenko, N [Laboratoire de Physique des Gaz et des Plasmas (CNRS-Universite Paris XI), Equipe Decharges Electriques et Environnement, Supelec, 91190 Gif sur Yvette (France); Petit, M [Service Electrotechnique et Electronique Industrielle, SUPELEC Plateau de Moulon, 91192 Gif sur Yvette Cedex (France); Borra, J P [Laboratoire de Physique des Gaz et des Plasmas (CNRS-Universite Paris XI), Equipe Decharges Electriques et Environnement, Supelec, 91190 Gif sur Yvette (France)

2006-01-21

This work addresses the case of millimetre sized plane-to-plane dielectric barrier discharge with sinusoidal voltage between 1 and 60 kHz for different configurations in air at atmospheric pressure. The first aim of this work is to achieve a representative statistical analysis of the electrical characteristics of the microdischarges. The numerical data treatment presented here enables us to determine the maximum current, the duration, the amount of charge and the triggering voltage for each current pulse. Both the average values as well as the deviations are checked. The relative influence of the operating parameters (voltage, gas flow rate, gap width, frequency) on the local surface polarization, electron attachment and temperature affecting microdischarge characteristics has been depicted in different arrangements. A special attention is paid to the influence of dielectric walls inside the discharge gap, perpendicular to the electrodes. Besides, this study allows the identification of the operating conditions for which all the microdischarges can be considered identical to study the local physical and chemical processes around each microdischarge.

A compact nanosecond pulse generator for DBD tube characterization

Science.gov (United States)

Rai, S. K.; Dhakar, A. K.; Pal, U. N.

2018-03-01

High voltage pulses of very short duration and fast rise time are required for generating uniform and diffuse plasma under various operating conditions. Dielectric Barrier Discharge (DBD) has been generated by high voltage pulses of short duration and fast rise time to produce diffuse plasma in the discharge gap. The high voltage pulse power generators have been chosen according to the requirement for the DBD applications. In this paper, a compact solid-state unipolar pulse generator has been constructed for characterization of DBD plasma. This pulsar is designed to provide repetitive pulses of 315 ns pulse width, pulse amplitude up to 5 kV, and frequency variation up to 10 kHz. The amplitude of the output pulse depends on the dc input voltage. The output frequency has been varied by changing the trigger pulse frequency. The pulsar is capable of generating pulses of positive or negative polarity by changing the polarity of pulse transformer's secondary. Uniform and stable homogeneous dielectric barrier discharge plasma has been produced successfully in a xenon DBD tube at 400-mbar pressure using the developed high voltage pulse generator.

Hexagon and stripe patterns in dielectric barrier streamer discharge

International Nuclear Information System (INIS)

Dong Lifang; He Yafeng; Yin Zengqian; Chai Zhifang

2004-01-01

We present a specially designed dielectric barrier discharge (DBD) system for the study of pattern formation. Hexagon and stripe patterns have been observed in a streamer discharge in a DBD for the first time. The phase diagram of pattern types as a function of applied voltage is given

Pulsed electromagnetic field radiation from a narrow slot antenna with a dielectric layer

NARCIS (Netherlands)

Štumpf, M.; De Hoop, A.T.; Lager, I.E.

2010-01-01

Analytic time domain expressions are derived for the pulsed electromagnetic field radiated by a narrow slot antenna with a dielectric layer in a two?dimensional model configuration. In any finite time window of observation, exact pulse shapes for the propagated, reflected, and refracted wave

Hydrodynamical flows in dielectric liquid in strong inhomogeneous pulsed electric field

International Nuclear Information System (INIS)

Tereshonok, Dmitry V; Babaeva, Natalia Yu; Naidis, George V; Smirnov, Boris M

2016-01-01

We consider a hydrodynamical flow of dielectric liquid near a high voltage needle-shaped electrode in a strong inhomogeneous pulsed electric field. It was shown that under a small rise time, a negative pressure area (pressure is less than critical pressure) appears near the electrode leading to the formation of a cavity in which electric breakdown can develop. A comparison of the dependence of the velocity of fluid near an electrode for two cases (taking into account the dependence of dielectric permeability of the liquid on the electric field and without taking it into account) was made. A field-dependent dielectric coefficient leads to the appearance of two local maximums of the velocities and increases the minimum pressure, thus lowering the possibility of cavitation. While under the constant value of dielectric permeability only one local maximum appears. (paper)

A Brief Study on the Ignition of the Non-Thermal Atmospheric Pressure Plasma Jet from a Double Dielectric Barrier Configured Plasma Pencil

International Nuclear Information System (INIS)

Begum, Asma; Laroussi, Mounir; Pervez, M. R.

2013-01-01

To understand the self sustained propagation of the plasma jet/bullet in air under atmospheric pressure, the ignition of the plasma jet/bullet, the plasma jet/bullet ignition point in the plasma pencil, the formation time and the formation criteria from a dielectric barrier configured plasma pencil were investigated in this study. The results were confirmed by comparing these results with the plasma jet ignition process in the plasma pencil without a dielectric barrier. Electrical, optical, and imaging techniques were used to study the formation of the plasma jet from the ignition of discharge in a double dielectric barrier configured plasma pencil. The investigation results show that the plasma jet forms at the outlet of the plasma pencil as a donut shaped discharge front because of the electric field line along the outlet's surface. It is shown that the required time for the formation of the plasma jet changes with the input voltage of the discharge. The input power calculation for the gap discharge and for the whole system shows that 56% of the average input power is used by the first gap discharge. The estimated electron density inside the gap discharge is in the order of 10 11 cm −3 . If helium is used as a feeding gas, a minimum 1.48×10 −8 C charge is required per pulse in the gap discharge to generate a plasma jet

Quantum computer based on activated dielectric nanoparticles selectively interacting with short optical pulses

International Nuclear Information System (INIS)

Gadomskii, Oleg N; Kharitonov, Yu Ya

2004-01-01

The operation principle of a quantum computer is proposed based on a system of dielectric nanoparticles activated with two-level atoms - cubits, in which electric dipole transitions are excited by short intense optical pulses. It is proved that the logical operation (logical operator) CNOT (controlled NOT) is performed by means of time-dependent transfer of quantum information over 'long' (of the order of 10 4 nm) distances between spherical nanoparticles owing to the delayed interaction between them in the optical radiation field. It is shown that one-cubit and two-cubit logical operators required for quantum calculations can be realised by selectively exciting dielectric particles with short optical pulses. (quantum calculations)

Development of Compact Ozonizer with High Ozone Output by Pulsed Power

Science.gov (United States)

Tanaka, Fumiaki; Ueda, Satoru; Kouno, Kanako; Sakugawa, Takashi; Akiyama, Hidenori; Kinoshita, Youhei

Conventional ozonizer with a high ozone output using silent or surface discharges needs a cooling system and a dielectric barrier, and therefore becomes a large machine. A compact ozonizer without the cooling system and the dielectric barrier has been developed by using a pulsed power generated discharge. The wire to plane electrodes made of metal have been used. However, the ozone output was low. Here, a compact and high repetition rate pulsed power generator is used as an electric source of a compact ozonizer. The ozone output of 6.1 g/h and the ozone yield of 86 g/kWh are achieved at 500 pulses per second, input average power of 280 W and an air flow rate of 20 L/min.

Effects of pulse-to-pulse residual species on discharges in repetitively pulsed discharges through packed bed reactors

Science.gov (United States)

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

2016-09-01

Atmospheric pressure dielectric barrier discharges (DBDs) sustained in packed bed reactors (PBRs) are being investigated for conversion of toxic and waste gases, and CO2 removal. These discharges are repetitively pulsed having varying flow rates and internal geometries, which results in species from the prior pulse still being in the discharge zone at the time the following discharge pulse occurs. A non-negligible residual plasma density remains, which effectively acts as preionization. This residual charge changes the discharge properties of subsequent pulses, and may impact important PBR properties such as chemical selectivity. Similarly, the residual neutral reactive species produced during earlier pulses will impact the reaction rates on subsequent pulses. We report on results of a computational investigation of a 2D PBR using the plasma hydrodynamics simulator nonPDPSIM. Results will be discussed for air flowing though an array of dielectric rods at atmospheric pressure. The effects of inter-pulse residual species on PBR discharges will be quantified. Means of controlling the presence of residual species in the reactor through gas flow rate, pulse repetition, pulse width and geometry will be described. Comparisons will be made to experiments. Work supported by US DOE Office of Fusion Energy Science and the National Science Foundation.

High-voltage pulsed life of multistressed polypropylene capacitor dielectric

International Nuclear Information System (INIS)

Laghari, J.R.

1992-01-01

High-voltage polypropylene capacitors were aged under singular as well as simultaneous multiple stresses (electrical, thermal, and radiation) at the University of Buffalo's 2 MW thermal nuclear reactor. These stresses were combined neutron-gamma radiation with a total dose of 1.6 x 10 6 rad, electrical stress at 40 V rms /μm, and thermal stress at 90 degrees C. After exposure, the polypropylene dielectric was tested for life (number of pulses to fail) under high-voltage high-repetition-rate (100 pps) pulses. Pulsed life data were also compared with ac life data. Results show that radiation stress causes the most degradation in life, either acting alone or in combination with other stresses. The largest reduction in life occurs when polypropylene is aged under simultaneous multiple stresses (electrical, thermal, and radiation). In this paper, it is shown that pulsed life can be equivalently compared with ac life

Application of dielectric surface barrier discharge for food storage

Directory of Open Access Journals (Sweden)

Yassine BELLEBNA

2015-12-01

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

Dielectric breakdown and healing of anodic oxide films on aluminium under single pulse anodizing

International Nuclear Information System (INIS)

Sah, Santosh Prasad; Tatsuno, Yasuhiro; Aoki, Yoshitaka; Habazaki, Hiroki

2011-01-01

Research highlights: → We examined dielectric breakdown of anodic alumina by single pulse anodizing. → Current transients and morphology of discharge channels are dependent upon electrolyte and voltage. → There is a good correlation between current transient and morphology of discharge channel. → Healing of open discharge pores occurs in alkaline silicate, but not in pentaborate electrolyte. - Abstract: Single pulse anodizing of aluminium micro-electrode has been employed to study the behaviour of dielectric breakdown and subsequent oxide formation on aluminium in alkaline silicate and pentaborate electrolytes. Current transients during applying pulse voltage have been measured, and surface has been observed by scanning electron microscopy. Two types of current transients are observed, depending on the electrolyte and applied voltage. There is a good correlation between the current transient behaviour and the shape of discharge channels. In alkaline silicate electrolyte, circular open pores are healed by increasing the pulse width, but such healing is not obvious in pentaborate electrolyte.

Experimental investigation on large-area dielectric barrier discharge in atmospheric nitrogen and air assisted by the ultraviolet lamp.

Science.gov (United States)

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

2009-04-01

In this paper, ultraviolet radiation produced by the ultraviolet lamp is employed to supply pre-ionization for the dielectric barrier discharge in N(2) or air at atmospheric pressure. The effect of the ultraviolet pre-ionization on improving the uniformity of the dielectric barrier discharge is investigated experimentally. The atmospheric pressure glow discharge of the large area (270 mm x 120 mm) is obtained successfully via the ultraviolet pre-ionization in atmospheric DBD in N(2) when the gas gap decrease to 3mm. Based on the emission spectra, the mechanism which ultraviolet pre-ionization improves the uniformity of the dielectric barrier discharge is discussed.

Dielectric barrier discharge processing of aerospace materials

International Nuclear Information System (INIS)

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

2004-01-01

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

Electrophoretically applied dielectrics for amorphous metal foils used in pulsed power saturable reactors

International Nuclear Information System (INIS)

Sharp, D.J.; Harjes, H.C.; Mann, G.A.

1989-01-01

Amorphous metal foil-wound inductors have been tested as ferromagnetic saturable inductive elements for pulsed-power (multi-terawatt) switching modules in the inertial confinement fusion program at Sandia National Laboratories. In simulated capacitor testing premature dielectric breakdown of thin polyethylene terephthalate film insulation in the inductor windings occurs at considerably below 2500 V. This appears to be due to inadvertant dielectric damage from micro-spikes on the amorphous foil surface. Electron micrographs and dielectric breakdown data illustrate that electrophoretically-applied dielectric coatings, deposited from organic aqueous colloid dispersions, can be used to provide insulating coatings on the foil which provide a 240% improvement (6000 V) in the breakdown strength of wound amorphous foil inductors. The theory and operation of a dedicated electrophoretic continuous coating system is described. The machine was constructed and successfully applied for dielectric coating of amorphous metal foil. Additional possible applications exist for practical dielectric coating of metallic films or foils used in various commercial wound-type capacitor structures. 7 refs., 9 figs

Atmospheric pressure dielectric barrier discharges for sterilization and surface treatment

Energy Technology Data Exchange (ETDEWEB)

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

2015-04-24

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

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

International Nuclear Information System (INIS)

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

2013-01-01

Highlights: • Benzene was successfully degraded by dielectric barrier/packed-bed discharge plasmas. • Different electrode geometry has distinct effect on plasmas oxidation performance. • Benzene degradation and energy performance were enhanced when using the coil electrode. • The reaction products were well determined by online FTIR analysis. -- Abstract: In this study, the effects of electrode geometry on benzene degradation in a dielectric barrier/packed-bed discharge plasma reactor with different electrodes were systematically investigated. Three electrodes were employed in the experiments, these were coil, bolt, and rod geometries. The reactor using the coil electrode showed better performance in reducing the dielectric loss in the barrier compared to that using the bolt or rod electrodes. In the case of the coil electrode, both the benzene degradation efficiency and energy yield were higher than those for the other electrodes, which can be attributed to the increased role of surface mediated reactions. Irrespective of the electrode geometry, the packed-bed discharge plasma was superior to the dielectric barrier discharge plasma in benzene degradation at any specific applied voltage. The main gaseous products of benzene degradation were CO, CO 2 , H 2 O, and formic acid. Discharge products such as O 3 , N 2 O, N 2 O 5 , and HNO 3 were also detected in the outlet gas. Moreover, the presence of benzene inhibited the formation of ozone because of the competing reaction of oxygen atoms with benzene. This study is expected to offer an optimized approach combining dielectric barrier discharge and packed-bed discharge to improve the degradation of gaseous pollutants

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

KAUST Repository

Zhang, Xuming; Cha, Min

2015-01-01

We studied the relative importance of the reduced field intensity and the background reaction temperature in the partial oxidation of methane in a temperature-controlled dielectric barrier discharge reactor. We obtained important mechanistic insight

Electron current extraction from radio frequency excited micro-dielectric barrier discharges

International Nuclear Information System (INIS)

Wang, Jun-Chieh; Kushner, Mark J.; Leoni, Napoleon; Birecki, Henryk; Gila, Omer

2013-01-01

Micro dielectric barrier discharges (mDBDs) consist of micro-plasma devices (10–100 μm diameter) in which the electrodes are fully or partially covered by dielectrics, and often operate at atmospheric pressure driven with radio frequency (rf) waveforms. In certain applications, it may be desirable to extract electron current out of the mDBD plasma, which necessitates a third electrode. As a result, the physical structure of the m-DBD and the electron emitting properties of its materials are important to its operation. In this paper, results from a two-dimensional computer simulation of current extraction from mDBDs sustained in atmospheric pressure N 2 will be discussed. The mDBDs are sandwich structures with an opening of tens-of-microns excited with rf voltage waveforms of up to 25 MHz. Following avalanche by electron impact ionization in the mDBD cavity, the plasma can be expelled from the cavity towards the extraction electrode during the part of the rf cycle when the extraction electrode appears anodic. The electron current extraction can be enhanced by biasing this electrode. The charge collection can be controlled by choice of rf frequency, rf driving voltage, and permittivity of the dielectric barrier.

Stepwise expansion of a surface dielectric barrier discharge as a result of alternation in formation of streamers and leaders

International Nuclear Information System (INIS)

Akishev, Yu; Aponin, G; Balakirev, A; Grushin, M; Petryakov, A; Karal'nik, V; Trushkin, N

2013-01-01

Spatial–temporal development of the plasma sheet structure in a surface dielectric barrier discharge (SDBD) powered with a single long pulse of negative polarity is traced. Ambient air and Ar at atmospheric pressure are used as plasma-forming gases. It is found that current regimes and spatial structures occurring at the development of a long-pulsed discharge differ cardinally as compared with those of a short-pulsed SDBD. In the case of long-pulsed SDBDs, the expansion of the barrier area covered by the plasma sheet and seeded with a surface negative charge occurs in a stepwise manner due to cyclic alternation (one after another) in generation of surface streamers and formation of hot surface leaders from the streamers due to streamer–leader transitions. Leaders, in their turn, initiate new streamers, which serve again as precursors for next-step leader formation, and so on. However, the crucial role in surface charge deposition is played not by streamers and leaders but by a diffusive plasma sheet (DPS), which slowly extends from the sides of streamers and leaders. The expansion of the DPS occurs due to the ionization wave propagating from the sides of the streamers and leaders. The difference in spatial structures of a single long-pulsed and a steady-state sin SDBD is studied. In high-frequency sin SDBDs at negative half-cycle there are only leaders and DPS, but there are no streamers. The reason is that there is no necessity for the formation of leaders due to streamer–leader transitions—leaders are formed at the previous cycle and do not decay strongly till the beginning of the next cycle, and they recover themselves without streamers. (paper)

Theory of suppressing avalanche process of carrier in short pulse laser irradiated dielectrics

Energy Technology Data Exchange (ETDEWEB)

Deng, H. X., E-mail: hxdeng@uestc.edu.cn, E-mail: xtzu@uestc.edu.cn, E-mail: kaisun@umich.edu; Zu, X. T., E-mail: hxdeng@uestc.edu.cn, E-mail: xtzu@uestc.edu.cn, E-mail: kaisun@umich.edu; Xiang, X. [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China); Zheng, W. G.; Yuan, X. D. [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Sun, K., E-mail: hxdeng@uestc.edu.cn, E-mail: xtzu@uestc.edu.cn, E-mail: kaisun@umich.edu [Department of Materials Engineering and Sciences, University of Michigan, 413B Space Research Building, Ann Arbor, Michigan 48109-2143 (United States); Gao, F. [Pacific Northwest National Laboratory, P. O. Box 999, Richland, Washington 99352 (United States)

2014-05-28

A theory for controlling avalanche process of carrier during short pulse laser irradiation is proposed. We show that avalanche process of conduction band electrons (CBEs) is determined by the occupation number of phonons in dielectrics. The theory provides a way to suppress avalanche process and a direct judgment for the contribution of avalanche process and photon ionization process to the generation of CBEs. The obtained temperature dependent rate equation shows that the laser induced damage threshold of dielectrics, e.g., fused silica, increase nonlinearly with the decreases of temperature. Present theory predicts a new approach to improve the laser induced damage threshold of dielectrics.

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

International Nuclear Information System (INIS)

Barni, R; Biganzoli, I; Riccardi, C

2014-01-01

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

Dynamics of dielectric barrier discharges in different arrangements

International Nuclear Information System (INIS)

Gibalov, Valentin I; Pietsch, Gerhard J

2012-01-01

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

Electrical characterization of atmospheric pressure dielectric barrier discharge in air

International Nuclear Information System (INIS)

Shrestha, P.; Subedi, D.P.; Joshi, U.M.

2013-01-01

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

Improvement of Polytetrafluoroethylene Surface Energy by Repetitive Pulse Non-Thermal Plasma Treatment in Atmospheric Air

International Nuclear Information System (INIS)

Yang Guoqing; Zhang Guanjun; Zhang Wenyuan

2011-01-01

Improvement of polytetrafluoroethylene surface energy by non-thermal plasma treatment is presented, using a nanosecond-positive-edge repetitive pulsed dielectric barrier discharge generator in atmospheric air. The electrical parameters including discharging power, peak and density of micro-discharge current were calculated, and the electron energy was estimated. Surface treatment experiments of polytetrafluoroethylene films were conducted for both different applied voltages and different treating durations. Results show that the surface energy of polytetrafluoroethylene film could be improved to 40 mJ/m 2 or more by plasma treatment. Surface roughness measurement and surface X-ray photoelectron spectroscopy analysis indicate that there are chemical etching and implantation of polar oxygen groups in the sample surface treating process, resulting in the improvement of the sample surface energy. Compared with an AC source of 50 Hz, the dielectric barrier discharges generated by a repetitive pulsed source could provide higher peak power, lower mean power, larger micro-discharge current density and higher electron energy. Therefore, with the same applied peak voltage and treating duration, the improvement of polytetrafluoroethylene surface energy using repetitive pulsed plasma is more effective, and the plasma treatment process based on repetitive pulsed dielectric barrier discharges in air is thus feasible and applicable.

Dielectric constant and electrical conductivity of contaminated fine-grained soils and barrier materials

International Nuclear Information System (INIS)

Kaya, A.; Fang, H.Y.; Inyang, H.I.

1997-01-01

Characterization of contaminated fine-grained soils and tracking of contaminant migration within barriers have been challenging because current methods and/or procedures are labor and time-intensive, and destructive. To demonstrate the effective use of both dielectric constant and electrical conductivity in the characterization of contaminated fine-grained soils, pore fluids were prepared at different ionic strengths, and were used as permeates for kaolinite, bentonite and a local soil. Then, both dielectric constant and electrical conductivity of the soils were measured by means of a capacitor over a wide range of frequencies and moisture content. It was observed that although each soil has its unique dielectric constant and electrical conductivity at a given moisture content, increases in ionic strength cause a decrease in the dielectric constant of the system at very high frequencies (MHZ), whereas the dielectric constant increases at low frequencies (kHz). Electrical conductivity of a soil-water system is independent of frequency. However, it is a function of ionic strength of the pore fluid. It is clearly demonstrated that dielectric constant and electrical conductivity of soils are functions of both moisture content and ionic strength, and can be used to characterize the spatial and temporal levels of contamination. This method/procedure can be used in estimating the level of contamination as well as the direction of contaminant movement in the subsurface without the use of extensive laboratory testing. Based on obtained results, it was concluded that the proposed method/procedure is promising because it is non-destructive and provides a quick means of assessing the spatial distribution of contaminants in fine-grained soils and barriers

Effects of barrier composition and electroplating chemistry on adhesion and voiding in copper/dielectric diffusion barrier films

Energy Technology Data Exchange (ETDEWEB)

Birringer, Ryan P.; Dauskardt, Reinhold H. [Department of Materials Science and Engineering, Stanford University, Durand Building, Stanford, California 94305-4034 (United States); Shaviv, Roey [Novellus Systems Inc., 4000 North First Street, San Jose, California 95134 (United States); Geiss, Roy H.; Read, David T. [National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305 (United States)

2011-08-15

The effects of electroplating chemistry and dielectric diffusion barrier composition on copper voiding and barrier adhesion are reported. Adhesion was quantified using the four-point bend thin film adhesion technique, and voiding in the Cu films was quantified using scanning electron microscopy. A total of 12 different film stacks were investigated, including three different Cu electroplating chemistries and four different barrier materials (SiN, N-doped SiC, O-doped SiC, and dual-layer SiC). Both plating chemistry and barrier composition have a large effect on interface adhesion and voiding in the Cu film. X-ray photoelectron spectroscopy was used to investigate the segregation of Cu electroplating impurities, such as S and Cl, to the Cu/barrier interface. Secondary ion mass spectrometry was used to quantify oxygen content at the Cu/barrier interface in a subset of samples. This interface oxygen content is correlated with measured adhesion values.

Ozone production by pulsed dielectric barrier discharges in air at atmospheric pressure; Efficacite de production d'ozone par decharge electrique pulsee sur barriere isolante dans l'air a pression atmospherique

Energy Technology Data Exchange (ETDEWEB)

Odic, E.; Karimi, Ch. [Supelec, Service Electrotechnique et Electronique Industrielle, 91 - Gif-sur-Yvette (France); Dhainaut, M.; Goldman, A.; Goldman, M. [Supelec, Laboratoire de Physique des Gaz et des Plasmas (Univ. Paris-Sud/CNRS), Equipe Decharges Electriques et Environnement, 91 - Gif sur Yvette (France)

2005-02-01

Non-thermal plasmas have been extensively studied these past 20 years from a theoretical point of view, but also for practical applications. Atmospheric pressure electrical discharges appear as promising technologies for gas phase and aqueous phase pollution control applications. In such arrangements, arcing i.e. transition to thermal plasma, is classically prevented either by application of short high voltage pulses or by insulating one or both electrodes with a dielectric material. The aim of this paper is to report recent results on ozone formation indicating a significant increase of the energy yields by coupling these two techniques. The chemical behaviour of the discharge is correlated to its electrical characteristics. The physical role plaid by the dielectric surface is highlighted and an interpretation is proposed. (authors)

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

Science.gov (United States)

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

2016-06-01

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

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

International Nuclear Information System (INIS)

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

2016-01-01

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 NO 2 has a significant adverse effect on the production efficiency of ozone due to their oxidation to another nitrogen oxides and their catalytic effect. (paper)

Fluorescence measurement of atomic oxygen concentration in a dielectric barrier discharge

Czech Academy of Sciences Publication Activity Database

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

2017-01-01

Roč. 26, č. 6 (2017), s. 1-11, č. článku 065020. ISSN 0963-0252 R&D Projects: GA ČR GA14-23532S; GA ČR(CZ) GA17-04329S Institutional support: RVO:68081715 Keywords : TALIF * dielectric barrier discharge * O radicals Impact factor: 3.302, year: 2016

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

Energy Technology Data Exchange (ETDEWEB)

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

2011-09-19

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

Atomization of bismuthane in a dielectric barrier discharge: A mechanistic study

Czech Academy of Sciences Publication Activity Database

Kratzer, Jan; Zelina, Ondřej; Svoboda, Milan; Sturgeon, R. E.; Mester, Z.; Dědina, Jiří

2016-01-01

Roč. 88, č. 3 (2016), s. 1804-1811 ISSN 0003-2700 R&D Projects: GA ČR GA14-23532S Grant - others:GA AV ČR(CZ) M200311202 Institutional support: RVO:68081715 Keywords : dielectric barrier discharge * hydride generation * mechanistic study Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 6.320, year: 2016

Atomization of bismuthane in a dielectric barrier discharge: A mechanistic study

Czech Academy of Sciences Publication Activity Database

Kratzer, Jan; Zelina, Ondřej; Svoboda, Milan; Sturgeon, R. E.; Mester, Z.; Dědina, Jiří

2016-01-01

Roč. 88, č. 3 (2016), s. 1804-1811 ISSN 0003-2700 R&D Projects: GA ČR GA14-23532S Grant - others:GA AV ČR(CZ) M200311202 Institutional support: RVO:68081715 Keywords : dielectric barrier discharge * hydride generation * mechanistic study Subject RIV: CB - Analytical Chemistry , Separation Impact factor: 6.320, year: 2016

DIFFUSE DBD IN ATMOSPHERIC AIR AT DIFFERENT APPLIED PULSE WIDTHS

Directory of Open Access Journals (Sweden)

Ekaterina Alexandrovna Shershunova

2015-02-01

Full Text Available The paper deals with the realization and the diagnostics of the volume diffuse dielectric barrier discharge in 1-mm air gap when applying high voltage rectangular pulses to the electrodes. The effect of the applied pulse width on the discharge dissipated energy was studied in detail. It was found experimentally, the energy stayed nearly constant with the pulse elongation from 600 ns to 1 ms.

Saturated Resin Ectopic Regeneration by Non-Thermal Dielectric Barrier Discharge Plasma

Directory of Open Access Journals (Sweden)

Chunjing Hao

2017-11-01

Full Text Available Textile dyes are some of the most refractory organic compounds in the environment due to their complex and various structure. An integrated resin adsorption/Dielectric Barrier Discharge (DBD plasma regeneration was proposed to treat the indigo carmine solution. It is the first time to report ectopic regeneration of the saturated resins by non-thermal Dielectric Barrier Discharge. The adsorption/desorption efficiency, surface functional groups, structural properties, regeneration efficiency, and the intermediate products between gas and liquid phase before and after treatment were investigated. The results showed that DBD plasma could maintain the efficient adsorption performance of resins while degrading the indigo carmine adsorbed by resins. The degradation rate of indigo carmine reached 88% and the regeneration efficiency (RE can be maintained above 85% after multi-successive regeneration cycles. The indigo carmine contaminants were decomposed by a variety of reactive radicals leading to fracture of exocyclic C=C bond, which could cause decoloration of dye solution. Based on above results, a possible degradation pathway for the indigo carmine by resin adsorption/DBD plasma treatment was proposed.

Influence of ultrasonic irradiation on ozone generation in a dielectric barrier discharge

DEFF Research Database (Denmark)

Kusano, Yukihiro; Drews, J.; Leipold, Frank

2012-01-01

An atmospheric pressure dielectric barrier discharge (DBD) was generated in an N2/O2 gas mixture at room temperature with and without ultrasonic irradiation to investigate ozone production. Powerful ultrasonic irradiation with the sound pressure level of approximately 150 dB into the DBD can...

Numerical study of the influence of dielectric tube on propagation of atmospheric pressure plasma jet based on coplanar dielectric barrier discharge

Science.gov (United States)

Haixin, HU; Feng, HE; Ping, ZHU; Jiting, OUYANG

2018-05-01

A 2D fluid model was employed to simulate the influence of dielectric on the propagation of atmospheric pressure helium plasma jet based on coplanar dielectric barrier discharge (DBD). The spatio-temporal distributions of electron density, ionization rate, electrical field, spatial charge and the spatial structure were obtained for different dielectric tubes that limit the helium flow. The results show that the change of the relative permittivity of the dielectric tube where the plasma jet travels inside has no influence on the formation of DBD itself, but has great impact on the jet propagation. The velocity of the plasma jet changes drastically when the jet passes from a tube of higher permittivity to one of lower permittivity, resulting in an increase in jet length, ionization rate and electric field, as well as a change in the distribution of space charges and discharge states. The radius of the dielectric tube has a great influence on the ring-shaped or solid bullet structure. These results can well explain the behavior of the plasma jet from the dielectric tube into the ambient air and the hollow bullet in experiments.

(RTO) Characterization of the Time-dependent Behaviour of Dielectric Barrier Discharge Plasma Actuators

Science.gov (United States)

2014-06-19

excited by a sine -wave signal with peak- to-peak amplitudes between 7.2 kV and 10 kV, and frequencies of 2.5 kHz and 4 kHz. The results indicate that the...side length of 0.68 m, made of transparent PMMA, to isolate it from ambient disturbances. The plasma actuator was excited by a sine -wave signal, which... Portugal , 2008. 6Hanson, R., Houser, N., and Lavoie, P., “Dielectric material degradation monitoring of dielectric barrier discharge plasma actuators

Paired Pulse Basis Functions for the Method of Moments EFIE Solution of Electromagnetic Problems Involving Arbitrarily-shaped, Three-dimensional Dielectric Scatterers

Science.gov (United States)

MacKenzie, Anne I.; Rao, Sadasiva M.; Baginski, Michael E.

2007-01-01

A pair of basis functions is presented for the surface integral, method of moment solution of scattering by arbitrarily-shaped, three-dimensional dielectric bodies. Equivalent surface currents are represented by orthogonal unit pulse vectors in conjunction with triangular patch modeling. The electric field integral equation is employed with closed geometries for dielectric bodies; the method may also be applied to conductors. Radar cross section results are shown for dielectric bodies having canonical spherical, cylindrical, and cubic shapes. Pulse basis function results are compared to results by other methods.

Pulse Power Capability Of High Energy Density Capacitors Based on a New Dielectric Material

Science.gov (United States)

Winsor, Paul; Scholz, Tim; Hudis, Martin; Slenes, Kirk M.

1999-01-01

A new dielectric composite consisting of a polymer coated onto a high-density metallized Kraft has been developed for application in high energy density pulse power capacitors. The polymer coating is custom formulated for high dielectric constant and strength with minimum dielectric losses. The composite can be wound and processed using conventional wound film capacitor manufacturing equipment. This new system has the potential to achieve 2 to 3 J/cu cm whole capacitor energy density at voltage levels above 3.0 kV, and can maintain its mechanical properties to temperatures above 150 C. The technical and manufacturing development of the composite material and fabrication into capacitors are summarized in this paper. Energy discharge testing, including capacitance and charge-discharge efficiency at normal and elevated temperatures, as well as DC life testing were performed on capacitors manufactured using this material. TPL (Albuquerque, NM) has developed the material and Aerovox (New Bedford, MA) has used the material to build and test actual capacitors. The results of the testing will focus on pulse power applications specifically those found in electro-magnetic armor and guns, high power microwave sources and defibrillators.

Reduction of damage threshold in dielectric materials induced by negatively chirped laser pulses

International Nuclear Information System (INIS)

Louzon, E.; Henis, Z.; Pecker, S.; Ehrlich, Y.; Fisher, D.; Fraenkel, M.; Zigler, A.

2005-01-01

The threshold fluence for laser induced damage in wide band gap dielectric materials, fused silica and MgF 2 , is observed to be lower by up to 20% for negatively (down) chirped pulses than for positively (up) chirped, at pulse durations ranging from 60 fs to 1 ps. This behavior of the threshold fluence for damage on the chirp direction was not observed in semiconductors (silicon and GaAs). Based on a model including electron generation in the conduction band and Joule heating, it is suggested that the decrease in the damage threshold for negatively chirped pulse is related to the dominant role of multiphoton ionization in wide gap materials

Period multiplication and chaotic phenomena in atmospheric dielectric-barrier glow discharges

International Nuclear Information System (INIS)

Wang, Y. H.; Zhang, Y. T.; Wang, D. Z.; Kong, M. G.

2007-01-01

In this letter, evidence of temporal plasma nonlinearity in which atmospheric dielectric-barrier discharges undergo period multiplication and chaos using a one-dimensional fluid model is reported. Under the conditions conducive for chaotic states, several frequency windows are identified in which period multiplication and secondary bifurcations are observed. Such time-domain nonlinearity is important for controlling instabilities in atmospheric glow discharges

Applicability of the dielectric barrier discharge for helium ash measurements in the divertor region

Directory of Open Access Journals (Sweden)

Książek Ireneusz

2016-06-01

Full Text Available Controlled fusion based on the magnetic confinement of the plasma is one of the main aims of the Euro-fusion programme. In the fusion device, the hydrogen isotopes, in nuclear reactions, will produce helium nuclei. The products, as the ash, will be removed from the plasma in the region of the so-called divertor. Controlling the helium to hydrogen ratio in this ‘exhaust gas’ will provide information about the efficiency of the fusion process as well as of the efficiency of the helium removal system. One of the methods to perform this task is to study the properties of the discharge conducted in such exhaust gas. In this paper, the applicability of the dielectric barrier discharge (DBD is studied. This preliminary experiment shows a great potential in applicability of this kind of discharge. The optical as well as pulse-height spectra were studied, both revealing very promising properties. In the optical spectrum, one can observe well separated hydrogen and helium spectral lines, with intensities of the same order of magnitude. Moreover, in the registered spectral region, the molecular spectra are negligible. The pulse-height spectra reveal very distinct shape in helium and hydrogen. Checking of this spectrum could provide parallel (redundant information about the partial pressure of helium in the magnetic confinement fusion (MCF device exhaust gas.

Pile-up and defective pulse rejection by pulse shape discrimination in surface barrier detectors

International Nuclear Information System (INIS)

Sjoeland, K.A.; Kristiansson, P.

1994-01-01

A technique to reject pile-up pulses and defective tail pulses from surface barrier detectors by the use of pulse shape discrimination is demonstrated. The electronic implementation of the pulse shape discrimination is based upon the zero crossing technique and for data reduction multiparameter techniques are used. The characteristic τ value for pile-up rejection is shown to be less than 56 ns. Its effect on detection limits from tail reduction in Particle Elastic Scattering Analysis (PESA) and pile-up peak suppression is discussed. ((orig.))

Numerical study on the discharge characteristics and nonlinear behaviors of atmospheric pressure coaxial electrode dielectric barrier discharges

International Nuclear Information System (INIS)

Zhang Ding-Zong; Wang Yan-Hui; Wang De-Zhen

2017-01-01

The discharge characteristics and temporal nonlinear behaviors of the atmospheric pressure coaxial electrode dielectric barrier discharges are studied by using a one-dimensional fluid model. It is shown that the discharge is always asymmetrical between the positive pulses and negative pulses. The gas gap severely affects this asymmetry. But it is hard to acquire a symmetrical discharge by changing the gas gap. This asymmetry is proportional to the asymmetric extent of electrode structure, namely the ratio of the outer electrode radius to the inner electrode radius. When this ratio is close to unity, a symmetrical discharge can be obtained. With the increase of frequency, the discharge can exhibit a series of nonlinear behaviors such as period-doubling bifurcation, secondary bifurcation and chaotic phenomena. In the period-doubling bifurcation sequence the period- n discharge becomes more and more unstable with the increase of n . The period-doubling bifurcation can also be obtained by altering the discharge gas gap. The mechanisms of two bifurcations are further studied. It is found that the residual quasineutral plasma from the previous discharges and corresponding electric field distribution can weaken the subsequent discharge, and leads to the occurrence of bifurcation. (paper)

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

Energy Technology Data Exchange (ETDEWEB)

Xu, Shao-Wei; He, Feng; Wang, Yu; Li, Lulu; Ouyang, Ji-Ting [School of Physics, Beijing Institute of Technology, Beijing 100081 (China)

2013-08-15

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.

A high energy density relaxor antiferroelectric pulsed capacitor dielectric

Energy Technology Data Exchange (ETDEWEB)

Jo, Hwan Ryul; Lynch, Christopher S. [Department of Mechanical and Aerospace Engineering, University of California, Los Angeles (UCLA), Los Angeles, California 90095 (United States)

2016-01-14

Pulsed capacitors require high energy density and low loss, properties that can be realized through selection of composition. Ceramic (Pb{sub 0.88}La{sub 0.08})(Zr{sub 0.91}Ti{sub 0.09})O{sub 3} was found to be an ideal candidate. La{sup 3+} doping and excess PbO were used to produce relaxor antiferroelectric behavior with slim and slanted hysteresis loops to reduce the dielectric hysteresis loss, to increase the dielectric strength, and to increase the discharge energy density. The discharge energy density of this composition was found to be 3.04 J/cm{sup 3} with applied electric field of 170 kV/cm, and the energy efficiency, defined as the ratio of the discharge energy density to the charging energy density, was 0.920. This high efficiency reduces the heat generated under cyclic loading and improves the reliability. The properties were observed to degrade some with temperature increase above 80 °C. Repeated electric field cycles up to 10 000 cycles were applied to the specimen with no observed performance degradation.

Robust control of dielectric elastomer diaphragm actuator for human pulse signal tracking

Science.gov (United States)

Ye, Zhihang; Chen, Zheng; Asmatulu, Ramazan; Chan, Hoyin

2017-08-01

Human pulse signal tracking is an emerging technology that is needed in traditional Chinese medicine. However, soft actuation with multi-frequency tracking capability is needed for tracking human pulse signal. Dielectric elastomer (DE) is one type of soft actuating that has great potential in human pulse signal tracking. In this paper, a DE diaphragm actuator was designed and fabricated to track human pulse pressure signal. A physics-based and control-oriented model has been developed to capture the dynamic behavior of DE diaphragm actuator. Using the physical model, an H-infinity robust control was designed for the actuator to reject high-frequency sensing noises and disturbances. The robust control was then implemented in real-time to track a multi-frequency signal, which verified the tracking capability and robustness of the control system. In the human pulse signal tracking test, a human pulse signal was measured at the City University of Hong Kong and then was tracked using DE actuator at Wichita State University in the US. Experimental results have verified that the DE actuator with its robust control is capable of tracking human pulse signal.

Liposomal membrane disruption by means of miniaturized dielectric-barrier discharge in air: liposome characterization

Science.gov (United States)

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.

Pulsed laser deposition of oxide gate dielectrics for pentacene organic field-effect transistors

International Nuclear Information System (INIS)

Yaginuma, S.; Yamaguchi, J.; Itaka, K.; Koinuma, H.

2005-01-01

We have fabricated Al 2 O 3 , LaAlO 3 (LAO), CaHfO 3 (CHO) and CaZrO 3 (CZO) thin films for the dielectric layers of field-effect transistors (FETs) by pulsed laser deposition (PLD). The films exhibited very smooth surfaces with root-mean-squares (rms) roughnesses of ∼1.3 A as evaluated by using atomic force microscopy (AFM). The breakdown electric fields of Al 2 O 3 , LAO, CHO and CZO films were 7, 6, 10 and 2 MV/cm, respectively. The magnitude of the leak current in each film was low enough to operate FET. We performed a comparative study of pentacene FET fabricated using these oxide dielectrics as gate insulators. High field-effect mobility of 1.4 cm 2 /V s and on/off current ratio of 10 7 were obtained in the pentacene FET using LAO gate insulating film. Use of the LAO films as gate dielectrics has been found to suppress the hysteresis of pentacene FET operations. The LAO films are relevant to the dielectric layer of organic FETs

Formation and evolution of the glow-like dielectric barrier discharge at atmospheric pressure

NARCIS (Netherlands)

Starostin, S.A.; ElSabbagh, M.A.M.; Premkumar, P.A.; Vries, de H.W.; Paffen, R.M.J.; Creatore, M.; Sanden, van de M.C.M.

2008-01-01

Time resolved process of formation and evolution of the atmospheric pressure glow discharge was studied in the roll-to- roll plasma- enhanced chemical vapor deposition dielectric barrier discharge reactor operating in helium-free gas mixtures by means of fast ICCD imaging. It was observed that the

Dielectric Barrier Discharge based Mercury-free plasma UV-lamp for efficient water disinfection.

Science.gov (United States)

Prakash, Ram; Hossain, Afaque M; Pal, U N; Kumar, N; Khairnar, K; Mohan, M Krishna

2017-12-12

A structurally simple dielectric barrier discharge based mercury-free plasma UV-light source has been developed for efficient water disinfection. The source comprises of a dielectric barrier discharge arrangement between two co-axial quartz tubes with an optimized gas gap. The outer electrode is an aluminium baked foil tape arranged in a helical form with optimized pitch, while the inner electrode is a hollow aluminium metallic rod, hermetically sealed. Strong bands peaking at wavelengths 172 nm and 253 nm, along with a weak band peaking at wavelength 265 nm have been simultaneously observed due to plasma radiation from the admixture of xenon and iodine gases. The developed UV source has been used for bacterial deactivation studies using an experimental setup that is an equivalent of the conventional house-hold water purifier system. Deactivation studies for five types of bacteria, i.e., E. coli, Shigella boydii, Vibrio, Coliforms and Fecal coliform have been demonstrated with 4 log reductions in less than ten seconds.

Nanosecond pulse-width electron diode based on dielectric wall accelerator technology

Energy Technology Data Exchange (ETDEWEB)

Zhao, Quantang, E-mail: zhaoquantang@impcas.ac.cn [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Zhang, Z.M.; Yuan, P.; Cao, S.C.; Shen, X.K.; Jing, Y. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Yu, C.S. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Li, Z.P.; Liu, M.; Xiao, R.Q. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Zong, Y.; Wang, Y.R. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Zhao, H.W. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

2013-11-21

An electron diode using a short section of dielectric wall accelerator (DWA) has been under development at the Institute of Modern Physics (IMP), Chinese Academy of Sciences. Tests have been carried out with spark gap switches triggered by lasers. The stack voltage efficiency of a four-layer of Blumleins reached about 60–70% with gas filled spark gap switching. The generated pulse voltage of peak amplitude of 23 kV and pulse width of 5 ns is used to extract and accelerate an electron beam of 320 mA, measured by a fast current transformer. A nanosecond pulse width electron diode was achieved successfully. Furthermore, the principle of a DWA is well proven and the development details and discussions are presented in this article. -- Highlights: •The key technology of DWA, including switches and pulse forming lines were studied. •The SiC PCSS obtained from Shanghai Institute were tested. •Two layers ZIP lines (new structure) and four layers Blumlein lines were studied with laser triggered spark gap switches. •A nanosecond pulse-width electron diode based on DWA technologies is achieved and studied experimentally. •The principle of DWA is also proved by the diode.

Two-dimensional simulation of argon dielectric barrier discharge excited by a Gaussian voltage at atmospheric pressure

Science.gov (United States)

Xu, Yonggang; Wang, Jing; Li, Jing; Lei, Bingying; Tang, Jie; Wang, Yishan; Li, Yongfang; Zhao, Wei; Duan, Yixiang

2017-04-01

A two-dimensional self-consistent fluid model was employed to investigate the spatiotemporal characteristics of discharges in atmospheric pressure argon (Ar) dielectric barrier discharge driven by a Gaussian voltage. The simulation results show that a discharge with multiple current pulses occurs each half-cycle in the gas gap. A transition from the Townsend mode to the glow mode is observed with the increasing applied voltage each half-cycle at a lower driving frequency (7.5 kHz). It is also found that the glow mode survives all the discharge phases at a higher driving frequency (12.5 kHz and 40 kHz). The change in the discharge mode with the driving frequency mainly lies in the fact that a lot of charged particles created in the discharge gap have no enough time to drift and diffuse around, and then these particles are assembled in the discharge space at higher frequency. Additionally, the spatial distributions of the electron density indicate that a center-advantage discharge is ignited at the driving frequencies of interest, resulting in the radial non-uniformity of discharge because of the edge effects. However, this overall non-uniformity is weakened with the driving frequency increased to 40 kHz, at which concentric ring patterns are observed. These distinct behaviors are mainly attributed to the fact that many charged particles generated are trapped in the gas gap and then accumulated to make the extension along the radial direction due to the charged particles transport and diffusion, and that the effective overlapping of a large number of avalanches induced by the increased "seed" electron density with the driving frequency. Meanwhile, the surface charged particles accumulated on the dielectric barriers are also shown to play a role in the formation of the discharge structure.

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

Czech Academy of Sciences Publication Activity Database

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

2012-01-01

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

Collective phenomena in volume and surface barrier discharges

Science.gov (United States)

Kogelschatz, U.

2010-11-01

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

Effect of dual-dielectric hydrogen-diffusion barrier layers on the performance of low-temperature processed transparent InGaZnO thin-film transistors

Science.gov (United States)

Tari, Alireza; Wong, William S.

2018-02-01

Dual-dielectric SiOx/SiNx thin-film layers were used as back-channel and gate-dielectric barrier layers for bottom-gate InGaZnO (IGZO) thin-film transistors (TFTs). The concentration profiles of hydrogen, indium, gallium, and zinc oxide were analyzed using secondary-ion mass spectroscopy characterization. By implementing an effective H-diffusion barrier, the hydrogen concentration and the creation of H-induced oxygen deficiency (H-Vo complex) defects during the processing of passivated flexible IGZO TFTs were minimized. A bilayer back-channel passivation layer, consisting of electron-beam deposited SiOx on plasma-enhanced chemical vapor-deposition (PECVD) SiNx films, effectively protected the TFT active region from plasma damage and minimized changes in the chemical composition of the semiconductor layer. A dual-dielectric PECVD SiOx/PECVD SiNx gate-dielectric, using SiOx as a barrier layer, also effectively prevented out-diffusion of hydrogen atoms from the PECVD SiNx-gate dielectric to the IGZO channel layer during the device fabrication.

Treatment of EDTA contained reactor coolant using water dielectric barrier discharge plasma

International Nuclear Information System (INIS)

Song, Sang Heon; Kwon, Daniel; Kim, Gon Ho

2005-01-01

EDTA (Ethylene Diamine Tetraacetic Acid) is used as a main absorbent for the metal ion in the secondary loop of the nuclear reactor. Dissolving the wasted EDTA with low cost, therefore, is important issue for the maintenance of the nuclear power reactor and the protection of environment. EDTA is not easily biodegradable, furthermore these methods could make remained another pollutant as complex chemical compounds. Compared to chemical method, the physical methods, using the energetic particles and UVs, are more favorable because they dissociate the bonds of organic compounds directly without the secondary chemical reactions during the treatment. Recently, high energy electron beam, the plasma torch, and the water breakdown by high voltage pulse are applied to treatment of the waste water contained chemicals. Here consideration is narrow down to improve the interaction between the plasma and the chemical bonds of EDTA because the energetic particles; activated radicals, and UVs, are abundant in plasmas. The new method adapted of the water DBD (dielectric barrier discharge) which plasma generates directly on the top of the water contained EDTA is proposed. The application of DBD plasmas has been extended for cleaning the organic compounds from the contaminated surface and also for removing volatile organic chemicals (VOC) such as NO x and SO x from the exhausted gases. Here, the water DBD reactor (SEMTECH, SD-DWG-04-1) is consisted that the one electrode is a ceramic insulator and another one is the water itself. Interestingly, the one electrode, the water, is not the solid dielectric electrode. In this study, therefore, the characteristics with driving frequency are considered and the feasibility of this new method for the DBD treatment of EDTA contained water is demonstrated

Control of the hyperbolic dispersion of dielectrics by an ultrashort laser pulse

Science.gov (United States)

Zhang, Xiaoqin; Wang, Feng; Zhang, Fengshou; Yao, Yugui

2018-01-01

An idea of controlling hyperbolic dispersion of dielectric materials by an ultrashort laser pulse is proposed. Taking the diamond as a concrete example and using time-dependent density functional theory calculations, we show that the permittivity tensor of the material can be effectively tuned by an ultrashort laser pulse, serving as a transient hyperbolic medium with wide working frequency window. With easily tunable laser parameters, the material can even be switched by reversal of both elliptic and hyperbolic for a particular light frequency. Our result points out a route toward transient hyperbolic materials, and it offers methods to achieve tunable hyperbolic dispersion with great potential for ultrafast device applications.

Characterization of a dielectric barrier plasma gun discharging at atmospheric pressure

International Nuclear Information System (INIS)

Zhang Guangqiu; Ge Yuanjing; Zhang Yuefei; Chen Guangliang

2004-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

Ambrico, P F; Ambrico, M; Dilecce, G; De Benedictis, S [Consiglio Nazionale delle Ricerche, Istituto di Metodologie Inorganiche e dei Plasmi UOS Bari-c/o Dipartimento di Chimica, Universita degli Studi di Bari ' Aldo Moro' , via Orabona, 4, 70126 Bari (Italy); Colaianni, A [Dipartimento di Geologia e Geofisica, Universita degli Studi di Bari ' Aldo Moro' , via Orabona, 4, 70126 Bari (Italy); Schiavulli, L, E-mail: paolofrancesco.ambrico@cnr.i [Dipartimento Interateneo di Fisica, Universita degli Studi di Bari ' Aldo Moro' , via Orabona, 4, 70126 Bari (Italy)

2010-08-18

In this study, the charge trapping effect in alumina dielectric surfaces has been deeply investigated by means of a dedicated dielectric barrier discharge apparatus in different discharge regimes and gas mixtures. This work further validates our previous findings in the case of air discharges in a filamentary regime. Long lasting charge trapping has been evidenced by ex situ thermoluminescence characterizations of alumina dielectric barrier plates exposed to a plasma. The density of trapped surface charges was found to be higher in the glow discharge with respect to pseudo-glow and filamentary regimes, and for all regimes the minimum trap activation temperature was 390 K and the trap energy was less than or around 1 eV. This implies that in the case of glow discharges a higher reservoir of electrons is present. Also, the effect was found to persist for several days after running the discharge.

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

International Nuclear Information System (INIS)

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

2010-01-01

In this study, the charge trapping effect in alumina dielectric surfaces has been deeply investigated by means of a dedicated dielectric barrier discharge apparatus in different discharge regimes and gas mixtures. This work further validates our previous findings in the case of air discharges in a filamentary regime. Long lasting charge trapping has been evidenced by ex situ thermoluminescence characterizations of alumina dielectric barrier plates exposed to a plasma. The density of trapped surface charges was found to be higher in the glow discharge with respect to pseudo-glow and filamentary regimes, and for all regimes the minimum trap activation temperature was 390 K and the trap energy was less than or around 1 eV. This implies that in the case of glow discharges a higher reservoir of electrons is present. Also, the effect was found to persist for several days after running the discharge.

Simulation Tool for Dielectric Barrier Discharge Plasma Actuators at Atmospheric and Sub-Atmospheric Pressures, Phase I

Data.gov (United States)

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

Numerical simulation of torus breakdown to chaos in an atmospheric-pressure dielectric barrier discharge

International Nuclear Information System (INIS)

Zhang, J.; Wang, Y. H.; Wang, D. Z.

2013-01-01

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

Numerical simulation of torus breakdown to chaos in an atmospheric-pressure dielectric barrier discharge

Energy Technology Data Exchange (ETDEWEB)

Zhang, J.; Wang, Y. H.; Wang, D. Z. [Key Laboratory of Materials Modification by Laser, Electron, and Ion Beams, School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)

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.

Influence of ultrasonic irradiation on ozone generation in a dielectric barrier discharge

International Nuclear Information System (INIS)

Kusano, Y; Drews, J; Leipold, F; Fateev, A; Bardenshtein, A; Krebs, N

2012-01-01

An atmospheric pressure dielectric barrier discharge (DBD) was generated in an N 2 /O 2 gas mixture at room temperature with and without ultrasonic irradiation to investigate ozone production. Powerful ultrasonic irradiation with the sound pressure level of approximately 150 dB into the DBD can enhance ozone production especially when the DBD was driven at a frequency of 15 kHz.

Determination of Ionization Coefficient of Atmospheric Helium in Dielectric Barrier Discharge

International Nuclear Information System (INIS)

Zhuo, Liang; Hai-Yun, Luo; Xin-Xin, Wang; Bo, Lv; Zhi-Cheng, Guan; Li-Ming, Wang

2008-01-01

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

Analysis of two-dimensional microdischarge distribution in dielectric-barrier discharges

International Nuclear Information System (INIS)

Chirokov, A; Gutsol, A; Fridman, A; Sieber, K D; Grace, J M; Robinson, K S

2004-01-01

The two-dimensional spatial distribution of microdischarges in atmospheric pressure dielectric-barrier discharges (DBDs) in air was studied. Experimental images of DBDs (Lichtenberg figures) were obtained using photostimulable phosphors. The storage phosphor imaging method takes advantage of the linear response of the phosphor for characterization of microdischarge intensity and position. A microdischarge interaction model in DBDs is proposed and a Monte Carlo simulation of microdischarge interactions in the discharge is presented. Comparison of modelled and experimental images indicates interactions and short-range structuring of microdischarge channels

Collective Phenomena In Volume And Surface Barrier Discharges

Science.gov (United States)

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.

Dielectric and diffusion barrier multilayer for Cu(In,Ga)Se{sub 2} solar cells integration on stainless steel sheet

Energy Technology Data Exchange (ETDEWEB)

Amouzou, Dodji, E-mail: dodji.amouzou@fundp.ac.be [Research Centre in Physics of Matter and Radiation (PMR), University of Namur (FUNDP), Rue de Bruxelles, 61, 5000 Namur (Belgium); Guaino, Philippe; Fourdrinier, Lionel; Richir, Jean-Baptiste; Maseri, Fabrizio [CRM-Group, Boulevard de Colonster, B 57, 4000 Liège (Belgium); Sporken, Robert [Research Centre in Physics of Matter and Radiation (PMR), University of Namur (FUNDP), Rue de Bruxelles, 61, 5000 Namur (Belgium)

2013-09-02

For the fabrication of monolithically integrated flexible Cu(In, Ga)Se{sub 2}, CIGS modules on stainless steel, individual photovoltaic cells must be insulated from metal substrates by a barrier layer that can sustain high thermal treatments. In this work, a combination of sol–gel (organosilane-sol) and sputtered SiAlxOy forming thin diffusion barrier layers (TDBL) was prepared on stainless steel substrates. The deposition of organosilane-sol dielectric layers on the commercial stainless steel (maximal roughness, Rz = 500 nm and Root Mean Square roughness, RMS = 56 nm) induces a planarization of the surface (RMS = 16.4 nm, Rz = 176 nm). The DC leakage current through the dielectric layers was measured for the metal-insulator-metal (MIM) junctions that act as capacitors. This method allowed us to assess the quality of our TDBL insulating layer and its lateral uniformity. Indeed, evaluating a ratio of the number of valid MIM capacitors to the number of tested MIM capacitors, a yield of ∼ 95% and 50% has been reached respectively with non-annealed and annealed samples based on sol–gel double layers. A yield of 100% was achieved for sol–gel double layers reinforced with a sputtered SiAlxOy coating and a third sol–gel monolayer. Since this yield is obtained on several samples, it can be extrapolated to any substrate size. Furthermore, according to Glow Discharge Optical Emission Spectroscopy and Time of Flight Secondary Ion Mass Spectroscopy measurements, these barrier layers exhibit excellent barrier properties against the diffusion of undesired atoms which could otherwise spoil the electronic and optical properties of CIGS photovoltaic cells. - Highlights: • We functionalize steel for monolithically integrated Cu(In,Ga)Se{sub 2} solar cells • Thin dielectric and diffusion barrier layers (TDDBL) prepared on steel • Reliability and breakdown voltage of dielectric layers have been studied. • Investigation of thermal treatment effect on dielectric

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

International Nuclear Information System (INIS)

Slama, J.; Kriha, V.; Fantova, V.; Julak, J.

2013-01-01

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

Influence of duration and rate of pulse rise of the applied voltage on ozone concentration in the barrier glow discharge

International Nuclear Information System (INIS)

Krasnyj, V.V.; Klosovski, A.V.; Knysh, A.S.; Shvets, O.M.; Taran, V.S.; Tereshin, V.I.

2005-01-01

The barrier glow discharge between two planar electrodes, covered with dielectric, is studied under high-voltage pulsed power supply. Wide applications of such type of discharges, in particular, for ozone production, stimulated a number of investigations in this direction. In this work we investigated the dependence of ozone concentration on the duration and the rate of pulse rise of the applied voltage. The thyristor converter circuit with the shortening of input pulses on the base of the saturable throttle was used for the realization of this task. The output pulses with amplitude up to 15 kV, repetition frequency of 1 kHz, pulse duration of 0.3 μs (or 7 μs) and the rate of pulse rise of 0.1 μs were generated with this scheme. Measurements of the ozone concentration produced in the air mixture have shown that its value increased by factor two with variation of the rate of pulse rise from 0.5 μs to 0.1 μs (for pulse duration of 7 μs). The dependence of the ozone concentration on the variation of air mixture pressure in the discharge gap of reactor was investigated also. It was shown proportional increase of the output concentration of ozone with increasing the pressure value. Spectroscopic measurements carried out in the ultraviolet spectrum made it possible to analyze changing the concentration of ozone and nitric components. (author)

Simulation of N-atom production in dielectric-barrier discharge in nitrogen at atmospheric pressure

International Nuclear Information System (INIS)

Tsyganov, Dmitry; Pancheshnyi, Sergey

2012-01-01

A plasma-chemical model of atomic nitrogen production in a Townsend dielectric-barrier discharge in nitrogen at atmospheric pressure is presented. On the basis of the comparison with measured densities, a significant discrepancy between the calculated and the measured production rate of nitrogen atoms is observed and discussed. (paper)

Positron and positronium annihilation in low-dielectric-constant films studied by a pulsed positron beam

International Nuclear Information System (INIS)

Suzuki, R.; Ohdaira, T.; Kobayashi, Y.; Ito, K.; Yu, R.S.; Shioya, Y.; Ichikawa, H.; Hosomi, H.; Ishikiriyama, K.; Shirataki, H.; Matsuno, S.; Xu, J.

2004-01-01

Positron and positronium annihilation in porous low-dielectric-constant (low-k) films deposited by plasma-enhanced chemical vapor deposition (PECVD) and spin-on dielectric (SOD) have been investigated by means of positron annihilation lifetime spectroscopy (PALS) and age-momentum correlation (AMOC) spectroscopy with a pulsed slow positron beam. The ortho-positronium (o-Ps) lifetime strongly depends on the deposition condition. In general, PECVD low-k films have shorter o-Ps lifetimes than SOD low-k films, indicating PECVD low-k films have smaller pores. Since o-Ps diffusion and escaping from the surface occurs in most of porous SOD films, three-gamma annihilation measurement is important. To investigate o-Ps behavior in SOD films, we have carried out two-dimensional (2D) PALS measurement, which measures annihilation time and pulse-height of the scintillation detector simultaneously. Monte-Carlo simulation of the o-Ps diffusion and escaping in porous films has been carried out to simulate the 2D-PALS results. (orig.)

Experimental and modelling investigations of a dielectric barrier discharge in low-pressure argon

International Nuclear Information System (INIS)

Wagenaars, E; Brandenburg, R; Brok, W J M; Bowden, M D; Wagner, H-E

2006-01-01

The discharge behaviour of a dielectric barrier discharge (DBD) in low-pressure argon gas was investigated by experiments and modelling. The electrical characteristics and light emission dynamics of the discharge were measured and compared with the results of a two-dimensional fluid model. Our investigations showed that the discharge consisted of a single, diffuse discharge per voltage half-cycle. The breakdown phase of the low-pressure DBD (LPDBD) was investigated to be similar to the ignition phase of a low-pressure glow discharge without dielectrics, described by Townsend breakdown theory. The stable discharge phase of the LPDBD also showed a plasma structure with features similar to those of a classical glow discharge. The presence of the dielectric in the discharge gap led to the discharge quenching and thus the decay of the plasma. Additionally, the argon metastable density was monitored by measuring light emission from nitrogen impurities. A metastable density of about 5 x 10 17 m -3 was present during the entire voltage cycle, with only a small (∼10%) increase during the discharge. Finally, a reduction of the applied voltage to the minimum required to sustain the discharge led to a further reduction of the role of the dielectric. The discharge was no longer quenched by the dielectrics only but also by a reduction of the applied voltage

Study on characteristics of high frequency dielectric barrier discharge for the removal of organic pollutant adsorbed on activated carbon

Energy Technology Data Exchange (ETDEWEB)

Qu, G.Z.; Li, G.F. [Dalian Univ. of Technology, Dalian (China). Inst. of Electrostatics and Special Power; Li, J.; Lu, N.; Wu, Y.; Li, D. [Dalian Univ. of Technology, Dalian (China). Inst. of Electrostatics and Special Power; Key Lab of Industrial Ecology and Environmental Engineering, Ministry of Education, Dalian (China)

2010-07-01

Advanced oxidation technologies such as photocatalysis, electrochemical degradation, Fenton oxidation, hydrogen peroxide oxidation, and plasma oxidation are increasingly being used to degrade refractory biodegradable organic contaminants. The plasma oxidation method has the advantage of direct in situ production of multiple types of high-reactive chemical species, including molecules and radicals that facilitate the degradation reaction. In addition, plasma oxidation does not produce any secondary pollution. Compared to other plasma technologies, the dielectric barrier discharge (DBD) plasma has been considered as a promising technology for removing toxic compounds because of its stability and its treatability property of biologically recalcitrant compounds in wastewater. However, the energy efficiency of DBD requires improvement for economic reasons. This paper reported on an experimental study that investigated the electrical characteristics of a parallel plate DBD reactor using a high frequency power supply for the removal of pentachlorophenol (PCP) adsorbed on activated carbon (AC). This study examined the effects of AC with different mass on discharge characteristics and compared the voltage and current waveforms, and discharge images of DBD reactors with different dielectric configurations. When the DBD reactor filled with AC, the applied voltage of discharge decreased regardless of the DBD reactor configuration in terms of having a single barrier or two barriers. The discharge characteristics had no significant change with AC mass increasing. The discharge images and current waveforms showed that DBD reactor configuration consisting of two dielectrics is more homogeneous and stable than the one consisting of a single dielectric. Under the same electric field condition, the degradation efficiency of PCP in two barriers reactor is higher than that in single barrier reactor. It was concluded that the findings from this study may be instrumental in treating

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

Energy Technology Data Exchange (ETDEWEB)

Duben, Ondřej [Institute of Analytical Chemistry of the CAS, v.v.i., Veveří 97, CZ-602 00 Brno (Czech Republic); Faculty of Science, Department of Analytical Chemistry, Charles University in Prague, Hlavova 8, Prague, CZ 128 43 Czech Republic (Czech Republic); Boušek, Jaroslav [Faculty of Electrical Engineering and Communications, Brno University of Technology, Technická 1058/10, 61600 Brno (Czech Republic); Dědina, Jiří [Institute of Analytical Chemistry of the CAS, v.v.i., Veveří 97, CZ-602 00 Brno (Czech Republic); Kratzer, Jan, E-mail: jkratzer@biomed.cas.cz [Institute of Analytical Chemistry of the CAS, v.v.i., Veveří 97, CZ-602 00 Brno (Czech Republic)

2015-09-01

Atomization of selenium hydride in a quartz dielectric barrier discharge (DBD) atomizer was optimized and its performance was compared to that of the externally heated quartz multiatomizer. Argon was found as the best DBD discharge gas employing a flow rate of 75 ml min{sup −1} Ar while the DBD power was optimized at 14 W. The detection limits reached 0.24 ng ml{sup −1} Se in the DBD and 0.15 ng ml{sup −1} Se in the multiatomizer. The tolerance of DBD to interferences is even better than with the multiatomizer. - Highlights: • SeH{sub 2} atomization in a dielectric barrier discharge (DBD) was optimized for AAS. • Atomizer performance was compared for DBD and externally heated quartz atomizer. • Detection limits were quantified and interferences were studied in both atomizers. • Atomization efficiency in the DBD was estimated.

Analysis and experimental study on formation conditions of large-scale barrier-free diffuse atmospheric pressure air plasmas in repetitive pulse mode

Science.gov (United States)

Li, Lee; Liu, Lun; Liu, Yun-Long; Bin, Yu; Ge, Ya-Feng; Lin, Fo-Chang

2014-01-01

Atmospheric air diffuse plasmas have enormous application potential in various fields of science and technology. Without dielectric barrier, generating large-scale air diffuse plasmas is always a challenging issue. This paper discusses and analyses the formation mechanism of cold homogenous plasma. It is proposed that generating stable diffuse atmospheric plasmas in open air should meet the three conditions: high transient power with low average power, excitation in low average E-field with locally high E-field region, and multiple overlapping electron avalanches. Accordingly, an experimental configuration of generating large-scale barrier-free diffuse air plasmas is designed. Based on runaway electron theory, a low duty-ratio, high voltage repetitive nanosecond pulse generator is chosen as a discharge excitation source. Using the wire-electrodes with small curvature radius, the gaps with highly non-uniform E-field are structured. Experimental results show that the volume-scaleable, barrier-free, homogeneous air non-thermal plasmas have been obtained between the gap spacing with the copper-wire electrodes. The area of air cold plasmas has been up to hundreds of square centimeters. The proposed formation conditions of large-scale barrier-free diffuse air plasmas are proved to be reasonable and feasible.

Femtosecond pulse-width dependent trapping and directional ejection dynamics of dielectric nanoparticles

KAUST Repository

Chiang, Weiyi

2013-09-19

We demonstrate that laser pulse duration, which determines its impulsive peak power, is an effective parameter to control the number of optically trapped dielectric nanoparticles, their ejections along the directions perpendicular to polarization vector, and their migration distances from the trapping site. This ability to controllably confine and eject the nanoparticle is explained by pulse width-dependent optical forces exerted on nanoparticles in the trapping site and ratio between the repulsive and attractive forces. We also show that the directional ejections occur only when the number of nanoparticles confined in the trapping site exceeds a definite threshold. We interpret our data by considering the formation of transient assembly of the optically confined nanoparticles, partial ejection of the assembly, and subsequent filling of the trapping site. The understanding of optical trapping and directional ejections by ultrashort laser pulses paves the way to optically controlled manipulation and sorting of nanoparticles. © 2013 American Chemical Society.

LIF diagnostics of hydroxyl radical in atmospheric pressure He-H2O dielectric barrier discharges

Czech Academy of Sciences Publication Activity Database

Dilecce, G.; Ambrico, P. F.; Šimek, Milan; De Benedictis, S.

2012-01-01

Roč. 398, č. 4 (2012), s. 142-147 ISSN 0301-0104 Institutional research plan: CEZ:AV0Z20430508 Keywords : Spectroscopic Techniques * Plasma Diagnostics * LIF * OH * Dielectric Barrier Discharge Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.957, year: 2012

Control of the UV flux of a XeCl dielectric barrier discharge excilamp through its current variation

Energy Technology Data Exchange (ETDEWEB)

Piquet, H; Bhosle, S; Diez, R; Cousineau, M; Djibrillah, M; Le Thanh, D; Dagang, A N; Zissis, G

2012-02-28

The efficiency of the electrical power transfer to the gas mixture of a XeCl dielectric barrier discharge (DBD) exciplex lamp is analysed. An equivalent circuit model of the DBD is considered. It is shown that the excilamp power can be controlled by applying current to the lamp. This highly desired property is ensured by means of a specific power supply topology, whose concepts and design are discussed. The experimental prototype of a current-mode converter operating in the pulsed regime at pulse repetition rate of 50 kHz is presented and its capability to control the amount of energy transferred during each current pulse is demonstrated. The capability of this power supply to maintain specific operating conditions for the DBD lamp, with a very stable behaviour (even at a very low current, in the regime of a single discharge channel), is illustrated. The experimental results of a combined use of this converter and a XeCl excilamp are presented. The influence of the supply parameters on the 308-nm XeCl excilamp is analysed. The shape of the UV pulse of the lamp is experimentally shown to be similar to that of the current, which actually flows into the gas mixture. The UV radiation power is demonstrated to be tightly correlated to the current injected into the gas and controlled by the available degrees of freedom offered by the power supply. The measured UV output characteristics and performance of the system are discussed. Time resolved UV imaging of a XeCl DBD excilamp is used to analyse the mechanisms involved in the production of exciplexes at various power supply regimes. It is shown that a pulsed voltage source leads to formation of short high intensity UV peaks, while current pulses lead to formation of sustained discharge filaments. Based on the results of modelling of the above-mentioned operation conditions, the two power supply regimes are compared and analysed from the point of view of the UV power and radiative control.

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

Czech Academy of Sciences Publication Activity Database

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

2015-01-01

Roč. 111, SEP (2015), s. 57-63 ISSN 0584-8547 Grant - others:GA AV ČR(CZ) M200311202 Institutional support: RVO:68081715 Keywords : dielectric barrier discharge * hydride generation-atomic absorption spectrometry * selenium Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.289, year: 2015

Dielectric barrier discharge plasma treatment of cellulose nanofibre surfaces

DEFF Research Database (Denmark)

Kusano, Yukihiro; Madsen, Bo; Berglund, Linn

2017-01-01

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

Monitoring active species in an atmospheric pressure dielectric-barrier discharge: Observation of the Herman-infrared system

Czech Academy of Sciences Publication Activity Database

Annušová, A.; Čermák, P.; Rakovský, Jozef; Martišovitš, V.; Veis, P.

2017-01-01

Roč. 57, č. 2 (2017), s. 67-75 ISSN 0863-1042 Institutional support: RVO:61388955 Keywords : dielectric-barrier discharge * Herman-infrared system * nitrogen Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 1.440, year: 2016

Pulsed EM Field Response of a Thin, High-Contrast, Finely Layered Structure With Dielectric and Conductive Properties

NARCIS (Netherlands)

De Hoop, A.T.; Jiang, L.

2009-01-01

The response of a thin, high-contrast, finely layered structure with dielectric and conductive properties to an incident, pulsed, electromagnetic field is investigated theoretically. The fine layering causes the standard spatial discretization techniques to solve Maxwell's equations numerically to

A Novel Temperature Measurement Approach for a High Pressure Dielectric Barrier Discharge Using Diode Laser Absorption Spectroscopy (Preprint)

National Research Council Canada - National Science Library

Leiweke, R. J; Ganguly, B. N

2006-01-01

A tunable diode laser absorption spectroscopic technique is used to measure both electronically excited state production efficiency and gas temperature rise in a dielectric barrier discharge in argon...

Investigation of NOx Reduction by Low Temperature Oxidation Using Ozone Produced by Dielectric Barrier Discharge

DEFF Research Database (Denmark)

Stamate, Eugen; Irimiea, Cornelia; Salewski, Mirko

2013-01-01

NOx reduction by low temperature oxidation using ozone produced by a dielectric barrier discharge generator is investigated for different process parameters in a 6m long reactor in serpentine arrangement using synthetic dry flue gas with NOx levels below 500 ppm, flows up to 50 slm and temperatures...

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

International Nuclear Information System (INIS)

Yoon, Jae-San; Han, Jae-Hung

2014-01-01

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. (paper)

Excitons in semiconducting quantum filaments of CdS and CdSe with dielectric barriers

CERN Document Server

Dneprovskij, V S; Shalygina, O A; Lyaskovskij, V L; Mulyarov, E A; Gavrilov, S A; Masumoto, I

2002-01-01

The peculiarities of the luminescence spectra obtained by different polarization and intensity of the pumping excitation and luminescence kinetics of the CdS and CdSe nanocrystals are explained by the exciton transitions in the semiconducting quantum threads with dielectric barriers. The exciton transition energies correspond to the calculated ones with an account of both their dimensional quantization and the effect of the excitons dielectric intensification. It is shown that the excitons transition energies do not change by the change in the quantum threads diameter within the wide range, while the increase in the one-dimensional forbidden zone width of quantum thread by the decrease in its diameter is compensated through the decrease in the excitons binding energy

Evaluation of Novel Integrated Dielectric Barrier Discharge Plasma as Ozone Generator

Directory of Open Access Journals (Sweden)

Muhammad Nur

2017-04-01

Full Text Available This paper presents a characterization of an integrated ozone generator constructed by seven of reactors of Dielectric Barrier Discharge Plasma (DBDP. DBDP a has spiral-cylindrical configuration. Silence plasma produced ozone inside the DBDP reactor was generated by AC-HV with voltage up to 25 kV and maximum frequency of 23 kHz. As a source of ozone, dry air was pumped into the generator and controlled by valves system and a flowmeter. We found ozone concentration increased with the applied voltage, but in contrary, the concentration decreased with the flow rate of dry air. It was also found that a maximum concentration was 20 mg/L and ozone capacity of 48 g/h with an input power of 1.4 kW. Moreover, in this generator, IP efficiency of 8.13 g/kWh was obtained at input power 0.45 kW and air flow rate of 9 L/min. Therefore, be the higher ozone capacity can be produced with higher input power; however, it provided lower IP efficiency. The effect of dry air flow rate and applied voltage on ozone concentrations have been studied. At last, spiral wire copper was very corrosive done to the interaction with ozone, and it is necessary to do a research for finding the best metals as an active electrode inside of the quartz dielectric. Copyright © 2017 BCREC GROUP. All rights reserved Received: 18th July 2016; Revised: 25th September 2016; Accepted: 5th October 2016 How to Cite: Nur, M., Susan, A.I., Muhlisin, Z., Arianto, F., Kinandana, A.W., Nurhasanah, I., Sumariyah, S., Wibawa, P.J., Gunawan, G., Usman, A. (2017. Evaluation of Novel Integrated Dielectric Barrier Discharge Plasma as Ozone Generator. Bulletin of Chemical Reaction Engineering & Catalysis, 12 (1: 24-31 (doi:10.9767/bcrec.12.1.605.24-31 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.12.1.605.24-31

Pulsed laser planarization of metal films for multilevel interconnects

International Nuclear Information System (INIS)

Tuckerman, D.B.; Schmitt, R.L.

1985-05-01

Multilevel interconnect schemes for integrated circuits generally require one or more planarization steps, in order to maintain an acceptably flat topography for lithography and thin-film step coverage on the higher levels. Traditional approaches have involved planarization of the interlevel insulation (dielectric) layers, either by spin-on application (e.g., polyimide), or by reflow (e.g., phosphosilicate glass). We have pursued an alternative approach, in which each metal level is melted (hence planarized) using a pulsed laser prior to patterning. Short (approx.1 μs) pulses are used to preclude undesirable metallurgical reactions between the film, adhesion or barrier layer, and dielectric layer. Laser planarization of metals is particularly well suited to multilevel systems which include ground or power planes. Results are presented for planarization of gold films on SiO 2 dielectric layers using a flashlamp-pumped dye laser. The pulse duration is approx.1 μs, which allows the heat pulse to uniformly penetrate the gold while not penetrating substantially through the underlying SiO 2 (hence not perturbing the lower levels of metal). Excellent planarization of the gold films is achieved (less than 0.1 μm surface roughness, even starting with extreme topographic variations), as well as improved conductivity. To demonstrate the process, numerous planarized two-layer structures (transmission lines under a ground plane) were fabricated and characterized. 9 refs., 2 figs

Structural, Optical, and Dielectric Investigations of the Relaxor PLZT 9,75/65/35 Ceramics Irradiated by High-Current Pulsed Electron Beam

CERN Document Server

Efimov, V V; Kalmikov, A V; Klevtsova, E A; Minashkin, V F; Novikova, N N; Sikolenko, V V; Skripnik, A V; Sternberg, A; Tiutiunnikov, S I; Yakovlev, V A

2002-01-01

First time comprehensive study of high-current pulsed electron irradiation effects on the structural, optical and dielectric properties of relaxor (Pb_{(1-x)}La^{x}(Zr_{0.65}Ti_{0.35})_{1-x/4}O_{3} ceramics with x=9.75% has been provided. The electron beam had the following parameters: energy E_{e}=250 keV, current density J_{e}=1000 A/cm^{2}, pulse duration tau = 300 ns, density 10^{15} electrons/cm^{2} per pulse. Infrared reflectivity spectra in the region of 100-2000 cm^{-1} were obtained in virgin, irradiated by 1500 pulses and annealed up to t=500^{circ}C ceramics. The reconstruction of perovskite ABO_{3} structure in irradiated samples has been studied by complex use of X-ray and neutron scattering and IR spectroscopy techniques revealing the changes in transverse and longitudinal phonon modes, oscillators strength and damping of modes. Radiation effects on temperature behaviour of dielectric permittivity in the region of phase transition were studied. The possible mechanisms of pulsed electron irradiat...

Humidity effects on surface dielectric barrier discharge for gaseous naphthalene decomposition

Science.gov (United States)

Abdelaziz, Ayman A.; Ishijima, Tatsuo; Seto, Takafumi

2018-04-01

Experiments are performed using dry and humid air to clarify the effects of water vapour on the characteristics of surface dielectric barrier discharge (SDBD) and investigate its impact on the performance of the SDBD for decomposition of gaseous naphthalene in air stream. The current characteristics, including the discharge and the capacitive currents, are deeply analyzed and the discharge mechanism is explored. The results confirmed that the humidity affected the microdischarge distribution without affecting the discharge mode. Interestingly, it is found that the water vapour had a significant influence on the capacitance of the reactor due to its deposition on the discharge electrode and the dielectric, which, in turn, affects the power loss in the dielectric and the total power consumed in the reactor. Thus, the factor of the humidity effect on the power loss in the dielectric should be considered in addition to its effect on the attachment coefficient. Additionally, there was an optimum level of the humidity for the decomposition of naphthalene in the SDBD, and its value depended on the gas composition, where the maximum naphthalene decomposition efficiency in O2/H2O is achieved at the humidity level ˜10%, which was lower than that obtained in air/H2O (˜28%). The results also revealed that the role of the humidity in the decomposition efficiency was not significant in the humidified O2 at high power level. This was attributed to the significant increase in oxygen-derived species (such as O atoms and O3) at high power, which was enough to overcome the negative effects of the humidity.

Laser amplification in excited dielectrics

DEFF Research Database (Denmark)

Winkler, Thomas; Haahr-Lillevang, Lasse; Sarpe, Cristian

2018-01-01

Wide-bandgap dielectrics such as glasses or water are transparent at visible and infrared wavelengths. This changes when they are exposed to ultrashort and highly intense laser pulses. Different interaction mechanisms lead to the appearance of various transient nonlinear optical phenomena. Using...... these, the optical properties of dielectrics can be controlled from the transparent to the metal-like state. Here we expand this range by a yet unexplored mechanism in excited dielectrics: amplification. In a two-colour pump-probe experiment, we show that a 400nm femtosecond laser pulse is coherently...

Infrared gas phase study on plasma-polymer interactions in high-current diffuse dielectric barrier discharge

NARCIS (Netherlands)

Liu, Y.; Welzel, S.; Starostin, S. A.; van de Sanden, M. C. M.; Engeln, R.; de Vries, H. W.

2017-01-01

A roll-to-roll high-current diffuse dielectric barrier discharge at atmospheric pressure was operated in air and Ar/N2/O2 gas mixtures. The exhaust gas from the discharge was studied using a high-resolution Fourier-transform infrared spectrometer in the range from 3000 to 750?cm-1 to unravel the

Preconcentration and atomization of arsane in a dielectric barrier discharge with detection by atomic absorption spectrometry

Czech Academy of Sciences Publication Activity Database

Novák, Petr; Dědina, Jiří; Kratzer, Jan

2016-01-01

Roč. 88, č. 11 (2016), s. 6064-6070 ISSN 0003-2700 R&D Projects: GA ČR GA14-23532S Institutional support: RVO:68081715 Keywords : dielectric barrier discharge * hydride generation * arsenic preconcentration Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 6.320, year: 2016

Impact of volume and surface processes on the pre-ionization of dielectric barrier discharges: advanced diagnostics and fluid modeling

Science.gov (United States)

Nemschokmichal, Sebastian; Tschiersch, Robert; Höft, Hans; Wild, Robert; Bogaczyk, Marc; Becker, Markus M.; Loffhagen, Detlef; Stollenwerk, Lars; Kettlitz, Manfred; Brandenburg, Ronny; Meichsner, Jürgen

2018-05-01

The phenomenology and breakdown mechanism of dielectric barrier discharges are strongly determined by volume and surface memory effects. In particular, the pre-ionization provided by residual species in the volume or surface charges on the dielectrics influences the breakdown behavior of filamentary and diffuse discharges. This was investigated by advanced diagnostics such as streak camera imaging, laser photodetachment of negative ions and laser photodesorption of electrons from dielectric surfaces in correlation with 1D fluid modeling. The streak camera images show that an increasing number of residual charges in the volume changes the microdischarge breakdown in air-like gas mixtures from a cathode-directed streamer to a simultaneous propagation of cathode- and anode-directed streamers. In contrast, seed electrons are important for the pre-ionization if the density of residual charges in the volume is low. One source of seed electrons are negative ions, whose density exceeds the electron density during the pre-phase of diffuse helium-oxygen barrier discharges as indicated by the laser photodetachment experiments. Electrons desorbed from the cathodic dielectric have an even larger influence. They induce a transition from the glow-like to the Townsend-like discharge mode in nominally pure helium. Apart from analyzing the importance of the pre-ionization for the breakdown mechanism, the opportunities for manipulating the lateral structure and discharge modes are discussed. For this purpose, the intensity and diameter of a diffuse discharge in helium are controlled by an illuminated semiconducting barrier. Contribution to the Topical Issue "Fundamentals of Complex Plasmas", edited by Jürgen Meichsner, Michael Bonitz, Holger Fehske, Alexander Piel.

ANTIMICROBIAL TEXTILE PREPARED BY SILVER DEPOSITION ON DIELECTRIC BARRIER DISCHARGE TREATED COTTON/POLYESTER FABRIC

Directory of Open Access Journals (Sweden)

Mirjana Kostić

2008-11-01

Full Text Available The objective of this research was to impart the additional value on cotton//polyester (Co/PES fabrics (i.e. antimicrobial properties to improve the quality of life and thus to tap new markets with the product. In this paper, silver ions were incorporated in Co/PES fabrics by chemisorptions into the fabric previously treated in a dielectric barrier discharge (DBD. A series of the DBD fabric treatments were done in order to determine the most suitable experimental conditions for the DBD activation of the fabric surface, while the optimal conditions for silver ions sorption by Co/PES fabrics were determined by changing sorption conditions. The antimicrobial Co/PES fabrics prepared by dielectric barrier discharge mediated silver deposition show an antimicrobial activity against tested pathogens: S. aureus, E. coli, and C. albicans under in vitro conditions. The obtained results confirm the practicability of the plasma modification process and furthermore show that with some delays in the next step, i.e. silver ion sorption, we can get the increase in the amount of the sorbed silver ions; the maximum sorption capacity of modified Co/PES fabrics was 0.135 mmol of Ag+ ions per gram of a fabric.

Columnar discharge mode between parallel dielectric barrier electrodes in atmospheric pressure helium

Energy Technology Data Exchange (ETDEWEB)

Hao, Yanpeng; Zheng, Bin; Liu, Yaoge [School of Electric Power, South China University of Technology, Guangzhou 510640 (China)

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.

Relaxation and excitation electronic processes in dielectrics irradiated by ultrafast IR and VUV pulses

International Nuclear Information System (INIS)

Gaudin, J.

2005-11-01

We studied excitation and relaxation of electrons involved during interaction of visible and VUV femtosecond pulses with dielectrics. The generated population of hot electrons, having energy of few eV to few tens of eV above the bottom of the conduction band, is responsible of phenomena ranging to defect creation to optical breakdown. Owing to two techniques: photoemission and transient photoconductivity we improve the understanding of the The first photoemission experiments deal with dielectrics irradiated by 30 fs IR pulses. The photoemission spectra measured show a large population of electrons which energy rise up to 40 eV. We interpret this result in terms of a new absorption process: direct multi-photons inter-branch transitions. The 2. type of photoemission experiments are time resolved 'pump/probe' investigation. We study the relaxation of electrons excited by a VUV pulses. We used the high order harmonics (HOH) as light sources. We found surprisingly long decay time in the range of ps timescale. Last type of experiments is photoconductivity studies of diamond samples. Using HOH as light source we measure the displacement current induced by excited electrons in the conduction band. Those electrons relax mainly by impact ionisation creating secondary electrons. Hence by probing the number of electrons we were able to measure the efficiency of these relaxation processes. We observe a diminution of this efficiency when the energy of exciting photons is above 20 eV. Owing to Monte-Carlo simulation we interpret this result in terms of band structure effect. (author)

Active species delivered by dielectric barrier discharge filaments to bacteria biofilms on the surface of apple

International Nuclear Information System (INIS)

Cheng, He; Liu, Xin; Lu, Xinpei; Liu, Dawei

2016-01-01

The atmospheric pressure non-equilibrium plasma has shown a significant potential as a novel food decontamination technology. In this paper, we report a computational study of the intersection of negative streamer produced by air dielectric barrier discharge with bacteria biofilm on an apple surface. The structure, conductivities, and permittivities of bacteria biofilm have been considered in the Poisson's equations and transportation equations of charge and neutral species to realize self-consistent transportation of plasma between electrode and charging surfaces of apple. We find that the ionization near the biofilm facilitates the propagation of negative streamer when the streamer head is 1 mm from the biofilm. The structure of the biofilm results in the non-uniform distribution of ROS and RNS captured by flux and time fluence of these reactive species. The mean free path of charged species in μm scale permitted the plasma penetrate into the cavity of the biofilm, therefore, although the density of ROS and RNS decrease by 6–7 order of magnitude, the diffusion results in the uniform distribution of ROS and RNS inside the cavity during the pulse off period.

Active species delivered by dielectric barrier discharge filaments to bacteria biofilms on the surface of apple

Energy Technology Data Exchange (ETDEWEB)

Cheng, He; Liu, Xin; Lu, Xinpei [State Key Lab of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, WuHan, HuBei (China); IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240 (China); Liu, Dawei, E-mail: ldw636@msn.com [State Key Lab of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, WuHan, HuBei (China); IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240 (China); State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Xi' an (China)

2016-07-15

The atmospheric pressure non-equilibrium plasma has shown a significant potential as a novel food decontamination technology. In this paper, we report a computational study of the intersection of negative streamer produced by air dielectric barrier discharge with bacteria biofilm on an apple surface. The structure, conductivities, and permittivities of bacteria biofilm have been considered in the Poisson's equations and transportation equations of charge and neutral species to realize self-consistent transportation of plasma between electrode and charging surfaces of apple. We find that the ionization near the biofilm facilitates the propagation of negative streamer when the streamer head is 1 mm from the biofilm. The structure of the biofilm results in the non-uniform distribution of ROS and RNS captured by flux and time fluence of these reactive species. The mean free path of charged species in μm scale permitted the plasma penetrate into the cavity of the biofilm, therefore, although the density of ROS and RNS decrease by 6–7 order of magnitude, the diffusion results in the uniform distribution of ROS and RNS inside the cavity during the pulse off period.

Optical and microwave dielectric properties of pulsed laser deposited Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} thin film

Energy Technology Data Exchange (ETDEWEB)

Joseph, Andrews; Goud, J. Pundareekam; Raju, K. C. James [School of Physics, University of Hyderabad, Hyderabad, Telangana 500046 (India); Emani, Sivanagi Reddy [Advanced Center of Research in High Energy Materials (ACRHEM), School of Physics, University of Hyderabad, Telangana 500046 (India)

2016-05-23

Optical properties of pulsed laser deposited (PLD) sodium bismuth titanate thin films (NBT), are investigated at wavelengths of 190-2500 nm. Microwave dielectric properties were investigated using the Split Post Dielectric Resonator (SPDR) technique. At 10 GHz, the NBT films have a dielectric constant of 205 and loss tangent of 0.0373 at room temperature. The optical spectra analysis reveals that NBT thin films have an optical band gap E{sub g}=3.55 eV and it has a dielectric constant of 3.37 at 1000 nm with dielectric loss of 0.299. Hence, NBT is a promising candidate for photonic device applications.

Dielectric barrier discharges: progress on plasma sources and on the understanding of regimes and single filaments

Science.gov (United States)

Brandenburg, Ronny

2017-05-01

Dielectric barrier discharges (DBDs) are plasmas generated in configurations with an insulating (dielectric) material between the electrodes which is responsible for a self-pulsing operation. DBDs are a typical example of nonthermal atmospheric or normal pressure gas discharges. Initially used for the generation of ozone, they have opened up many other fields of application. Therefore DBDs are a relevant tool in current plasma technology as well as an object for fundamental studies. Another motivation for further research is the fact that so-called partial discharges in insulated high voltage systems are special types of DBDs. The breakdown processes, the formation of structures, and the role of surface processes are currently under investigation. This review is intended to give an update to the already existing literature on DBDs considering the research and development within the last two decades. The main principles and different modes of discharge generation are summarized. A collection of known as well as special electrode configurations and reactor designs will be presented. This shall demonstrate the different and broad possibilities, but also the similarities and common aspects of devices for different fields of applications explored within the last years. The main part is devoted to the progress on the investigation of different aspects of breakdown and plasma formation with the focus on single filaments or microdischarges. This includes a summary of the current knowledge on the electrical characterization of filamentary DBDs. In particular, the recent new insights on the elementary volume and surface memory mechanisms in these discharges will be discussed. An outlook for the forthcoming challenges on research and development will be given.

Dielectric barrier discharge plasma pretreatment on hydrolysis of microcrystalline cellulose

Science.gov (United States)

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

2017-04-01

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

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

Science.gov (United States)

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

2015-06-01

Cold atmospheric pressure plasmas are a promising alternative therapy for treatment of chronic wounds, as they have already shown in clinical trials. In this study an air dielectric barrier discharge (DBD) developed for therapeutic use in dermatology is characterized with respect to the plasma produced reactive oxygen species, namely atomic oxygen and ozone, which are known to be of great importance to wound healing. To understand the plasma chemistry of the applied DBD, xenon-calibrated two-photon laser-induced fluorescence spectroscopy and optical absorption spectroscopy are applied. The measured spatial distributions are shown and compared to each other. A model of the afterglow chemistry based on optical emission spectroscopy is developed to cross-check the measurement results and obtain insight into the dynamics of the considered reactive oxygen species. The atomic oxygen density is found to be located mostly between the electrodes with a maximum density of {{n}\\text{O}}=6× {{10}16} cm-3 . Time resolved measurements reveal a constant atomic oxygen density between two high voltage pulses. The ozone is measured up to 3 mm outside the active plasma volume, reaching a maximum value of {{n}{{\\text{O}3}}}=3× {{10}16} cm-3 between the electrodes.

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

Czech Academy of Sciences Publication Activity Database

Dvořák, P.; Talába, M.; Obrusník, A.; Kratzer, Jan; Dědina, Jiří

2017-01-01

Roč. 26, č. 8 (2017), č. článku 085002. ISSN 0963-0252 R&D Projects: GA ČR(CZ) GA17-04329S; GA ČR GA14-23532S Institutional support: RVO:68081715 Keywords : TALIF * dielectric barrier discharge * H radicals Subject RIV: CB - Analytical Chemistry, Separation OBOR OECD: Analytical chemistry Impact factor: 3.302, year: 2016

CO2 valorization by means of Dielectric Barrier Discharge

Science.gov (United States)

Machrafi, H.; Cavadias, S.; Amouroux, J.

2011-01-01

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

CO2 valorization by means of Dielectric Barrier Discharge

International Nuclear Information System (INIS)

Machrafi, H; Cavadias, S; Amouroux, J

2011-01-01

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

Electric field strength in a silicon surface barrier detector with the presence of a dielectric plasma column

International Nuclear Information System (INIS)

Kanno, Ikuo

1994-01-01

The dynamic change of the electric field strength in a silicon surface barrier detector (SSBD) is studied. With the presence of a dielectric plasma column in the depletion layer of the SSBD, the electric field strength inside/outside the plasma column is suppressed/enhanced. As the length and the dielectric constant of the plasma column become shorter and smaller, the suppression and enhancement of the electric field strength become less. The electric field strength recovers the initial state, when the plasma column disappears. When the electrons and holes are inside/outside the dielectric plasma column, they have less/more electric potential than the one they have when there is no plasma column. During the movement of the electron/hole outside the plasma column to the positive/negative electrode, the enhanced electric field strength becomes smaller. Electron and hole pairs, which are the parts of the dielectric plasma column, arrive at positive and negative electrodes, having insufficient electric potential to induce the unit charge. This paper shows that the presence of a dielectric plasma column explains the main part of the residual defect in a SSBD. ((orig.))

Enhanced dielectric properties of ZrO2 thin films prepared in nitrogen ambient by pulsed laser deposition

International Nuclear Information System (INIS)

Zhu, J; Li, T L; Pan, B; Zhou, L; Liu, Z G

2003-01-01

ZrO 2 thin films were fabricated in O 2 ambient and in N 2 ambient by pulsed laser deposition (PLD), respectively. X-ray diffraction revealed that films prepared at 400 deg. C remained amorphous. The dielectric properties of amorphous ZrO 2 films were investigated by measuring the capacitance-frequency characteristics of Pt/ZrO 2 /Pt capacitor structures. The dielectric constant of the films deposited in N 2 ambient was larger than that of the films deposited in O 2 ambient. The dielectric loss was lower for films prepared in N 2 ambient. Atom force microscopy investigation indicated that films deposited in N 2 ambient had smoother surface than films deposited in O 2 ambient. Capacitance-voltage and current-voltage characteristics were studied. The equivalent oxide thickness (EOT) of films with 6.6 nm physical thickness deposited in N 2 ambient is lower than that of films deposited in O 2 ambient. An EOT of 1.38 nm for the film deposited in N 2 ambient was obtained, while the leakage current density was 94.6 mA cm -2 . Therefore, ZrO 2 thins deposited in N 2 ambient have enhanced dielectric properties due to the incorporation of nitrogen which leads to the formation of Zr-doped nitride interfacial layer, and is suggested to be a potential material for alternative high-k (high dielectric constant) gate dielectric applications

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

International Nuclear Information System (INIS)

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

2013-01-01

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.

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

Science.gov (United States)

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

2013-06-01

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

Simultaneous determination of arsenic and antimony by hydride generation atomic fluorescence spectrometry with dielectric barrier discharge atomizer

Energy Technology Data Exchange (ETDEWEB)

Xing Zhi [Department of Chemistry, Key Laboratory for Atomic and Molecular Nanosciences of the Education Ministry, Tsinghua University, Beijing 100084 (China); Kuermaiti, Biekesailike [Department of Chemistry, Key Laboratory for Atomic and Molecular Nanosciences of the Education Ministry, Tsinghua University, Beijing 100084 (China); Products Quality Inspection Institute, Yili, Xinjiang 835000 (China); Wang Juan; Han Guojun; Zhang Sichun [Department of Chemistry, Key Laboratory for Atomic and Molecular Nanosciences of the Education Ministry, Tsinghua University, Beijing 100084 (China); Zhang Xinrong, E-mail: xrzhang@mail.tsinghua.edu.cn [Department of Chemistry, Key Laboratory for Atomic and Molecular Nanosciences of the Education Ministry, Tsinghua University, Beijing 100084 (China)

2010-12-15

Simultaneous determination of As and Sb by hydride generation atomic fluorescence spectrometry was developed with the dielectric barrier discharge plasma as the hydride atomizer. The low-temperature and atmospheric-pressure micro-plasma was generated in a quartz cylindrical configuration device, which was constructed by an axial internal electrode and an outer electrode surrounding outside of the tube. The optimization of the atomizer construction and parameters for hydride generation and fluorescence detection systems were carried out. Under the optimized conditions, the detection limits for As and Sb were 0.04 and 0.05 {mu}g L{sup -1}, respectively. In addition, the applicability of the present method was confirmed by the detection of As and Sb in reference materials of quartz sandstone (GBW07106) and argillaceous limestone (GBW07108). The present work provided a new approach to exploit the miniaturized hydride generation dielectric barrier discharge atomic fluorescence spectrometry system for simultaneous multi-element determination.

Simultaneous determination of arsenic and antimony by hydride generation atomic fluorescence spectrometry with dielectric barrier discharge atomizer

International Nuclear Information System (INIS)

Xing Zhi; Kuermaiti, Biekesailike; Wang Juan; Han Guojun; Zhang Sichun; Zhang Xinrong

2010-01-01

Simultaneous determination of As and Sb by hydride generation atomic fluorescence spectrometry was developed with the dielectric barrier discharge plasma as the hydride atomizer. The low-temperature and atmospheric-pressure micro-plasma was generated in a quartz cylindrical configuration device, which was constructed by an axial internal electrode and an outer electrode surrounding outside of the tube. The optimization of the atomizer construction and parameters for hydride generation and fluorescence detection systems were carried out. Under the optimized conditions, the detection limits for As and Sb were 0.04 and 0.05 μg L -1 , respectively. In addition, the applicability of the present method was confirmed by the detection of As and Sb in reference materials of quartz sandstone (GBW07106) and argillaceous limestone (GBW07108). The present work provided a new approach to exploit the miniaturized hydride generation dielectric barrier discharge atomic fluorescence spectrometry system for simultaneous multi-element determination.

Experimental Study of SO2 Removal by Pulsed DBD Along with the Application of Magnetic Field

International Nuclear Information System (INIS)

Rong Mingzhe; Liu Dingxin; Wang Xiaohua; Wang Junhua

2007-01-01

Dielectric barrier discharge (DBD) for SO 2 removal from indoor air is investigated. In order to improve the removal efficiency, two novel methods are combined in this paper, namely by applying a pulsed driving voltage with nanosecond rising time and applying a magnetic field. For SO 2 removal efficiency, different matches of electric field and magnetic field are discussed. And nanosecond rising edge pulsed power supply and microsecond rising edge pulsed power supply are compared. It can be concluded that a pulsed DBD with nanosecond rising edge should be adopted, and electrical field and magnetic field should be applied in an appropriate match

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

Science.gov (United States)

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.

The relation between the production efficiency of nitrogen atoms and the electrical characteristics of a dielectric barrier discharge

NARCIS (Netherlands)

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

2015-01-01

In a nitrogen plasma jet, atomic nitrogen is the longest lived radical species and, through recombination, gives rise to highly reactive excited nitrogen species. In this paper, the atomic nitrogen concentration in the effluent of a nitrogen-fed dielectric barrier discharge (DBD) is determined by

Influence of surface emission processes on a fast-pulsed dielectric barrier discharge in air at atmospheric pressure

Science.gov (United States)

Pechereau, François; Bonaventura, Zdeněk; Bourdon, Anne

2016-08-01

This paper presents simulations of an atmospheric pressure air discharge in a point-to-plane geometry with a dielectric layer parallel to the cathode plane. Experimentally, a discharge reignition in the air gap below the dielectrics has been observed. With a 2D fluid model, it is shown that due to the fast rise of the high voltage applied and the sharp point used, a first positive spherical discharge forms around the point. Then this discharge propagates axially and impacts the dielectrics. As the first discharge starts spreading on the upper dielectric surface, in the second air gap with a low preionization density of {{10}4}~\\text{c}{{\\text{m}}-3} , the 2D fluid model predicts a rapid reignition of a positive discharge. As in experiments, the discharge reignition is much slower, a discussion on physical processes to be considered in the model to increase the reignition delay is presented. The limit case with no initial seed charges in the second air gap has been studied. First, we have calculated the time to release an electron from the cathode surface by thermionic and field emission processes for a work function φ \\in ≤ft[3,4\\right] eV and an amplification factor β \\in ≤ft[100,220\\right] . Then a 3D Monte Carlo model has been used to follow the dynamics of formation of an avalanche starting from a single electron emitted at the cathode. Due to the high electric field in the second air gap, we have shown that in a few nanoseconds, a Gaussian cloud of seed charges is formed at a small distance from the cathode plane. This Gaussian cloud has been used as the initial condition of the 2D fluid model in the second air gap. In this case, the propagation of a double headed discharge in the second air gap has been observed and the reignition delay is in rather good agreement with experiments.

Influence of Duty Cycle on Ozone Generation and Discharge Using Volume Dielectric Barrier Discharge

Czech Academy of Sciences Publication Activity Database

Wei, L.S.; Pongrác, Branislav; Zhang, Y.F.; Liang, X.; Prukner, Václav; Šimek, Milan

2018-01-01

Roč. 38, č. 2 (2018), s. 355-364 ISSN 0272-4324 R&D Projects: GA ČR(CZ) GA15-04023S Institutional support: RVO:61389021 Keywords : Ozone generation * Volume dielectric barrier discharge * Electrical characteristics * Duty cycle * Adjustable ozone concentration Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 2.355, year: 2016 https://link.springer.com/article/10.1007%2Fs11090-017-9866-y

Coiled transmission line pulse generators

Science.gov (United States)

McDonald, Kenneth Fox

2010-11-09

Methods and apparatus are provided for fabricating and constructing solid dielectric "Coiled Transmission Line" pulse generators in radial or axial coiled geometries. The pour and cure fabrication process enables a wide variety of geometries and form factors. The volume between the conductors is filled with liquid blends of monomers, polymers, oligomers, and/or cross-linkers and dielectric powders; and then cured to form high field strength and high dielectric constant solid dielectric transmission lines that intrinsically produce ideal rectangular high voltage pulses when charged and switched into matched impedance loads. Voltage levels may be increased by Marx and/or Blumlein principles incorporating spark gap or, preferentially, solid state switches (such as optically triggered thyristors) which produce reliable, high repetition rate operation. Moreover, these Marxed pulse generators can be DC charged and do not require additional pulse forming circuitry, pulse forming lines, transformers, or an a high voltage spark gap output switch. The apparatus accommodates a wide range of voltages, impedances, pulse durations, pulse repetition rates, and duty cycles. The resulting mobile or flight platform friendly cylindrical geometric configuration is much more compact, light-weight, and robust than conventional linear geometries, or pulse generators constructed from conventional components. Installing additional circuitry may accommodate optional pulse shape improvements. The Coiled Transmission Lines can also be connected in parallel to decrease the impedance, or in series to increase the pulse length.

Pre-breakdown processes in a dielectric fluid in inhomogeneous pulsed electric fields

Energy Technology Data Exchange (ETDEWEB)

Shneider, Mikhail N., E-mail: m.n.shneider@gmail.com [Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544 (United States); Pekker, Mikhail [MMSolution, 6808 Walker Street, Philadelphia, Pennsylvania 19135 (United States)

2015-06-14

We consider the development of pre-breakdown cavitation nanopores appearing in the dielectric fluid under the influence of the electrostrictive stresses in the inhomogeneous pulsed electric field. It is shown that three characteristic regions can be distinguished near the needle electrode. In the first region, where the electric field gradient is greatest, the cavitation nanopores, occurring during the voltage nanosecond pulse, may grow to the size at which an electron accelerated by the field inside the pores can acquire enough energy for excitation and ionization of the liquid on the opposite pore wall, i.e., the breakdown conditions are satisfied. In the second region, the negative pressure caused by the electrostriction is large enough for the cavitation initiation (which can be registered by optical methods), but, during the voltage pulse, the pores do not reach the size at which the potential difference across their borders becomes sufficient for ionization or excitation of water molecules. And, in the third, the development of cavitation is impossible, due to an insufficient level of the negative pressure: in this area, the spontaneously occurring micropores do not grow and collapse under the influence of surface tension forces. This paper discusses the expansion dynamics of the cavitation pores and their most probable shape.

Removal of ammonia from gas streams with dielectric barrier discharge plasmas

International Nuclear Information System (INIS)

Xia Lanyan; Huang Li; Shu Xiaohong; Zhang Renxi; Dong Wenbo; Hou Huiqi

2008-01-01

We reported on the experimental study of gas-phase removal of ammonia (NH 3 ) via dielectric barrier discharge (DBD) at atmospheric pressure, in which we mainly concentrated on three aspects-influence of initial NH 3 concentration, peak voltage, and gas residence time on NH 3 removal efficiency. Effectiveness, e.g. the removal efficiency, specific energy density, absolute removal amount and energy yield, of the self-made DBD reactor had also been studied. Basic analysis on DBD physical parameters and its performance was made in comparison with previous investigation. Moreover, products were detected via ion exchange chromatography (IEC). Experimental results demonstrated the application potential of DBD as an alternative technology for odor-causing gases elimination from gas streams

The impact of porosity on the formation of manganese based copper diffusion barrier layers on low-κ dielectric materials

International Nuclear Information System (INIS)

McCoy, A P; Bogan, J; Walsh, L; Byrne, C; O’Connor, R; Hughes, G; Woicik, J C

2015-01-01

This work investigates the impact of porosity in low-κ dielectric materials on the chemical and structural properties of deposited Mn thin films for copper diffusion barrier layer applications. X-ray photoelectron spectrscopy (XPS) results highlight the difficulty in distinguishing between the various Mn oxidation states which form at the interlayer dielectric (ILD)/Mn interface. The presence of MnSiO 3 and MnO were identified using x-ray absorption spectroscopy (XAS) measurements on both porous and non-porous dielectric materials with evidence of Mn 2 O 3 and Mn 3 O 4 in the deposited film on the latter surface. It is shown that a higher proportion of deposited Mn converts to Mn silicate on an ILD film which has 50% porosity compared with the same dielectric material with no porosity, which is attributed to an enhanced chemical interaction with the effective larger surface area of porous dielectric materials. Transmission electron microscopy (TEM) and energy-dispersive x-ray spectroscopy (EDX) data shows that the Mn overlayer remains predominately surface localised on both porous and non-porous materials. (paper)

Physics and applications of micro-plasmas in dielectric barrier and hollow cathode configurations

International Nuclear Information System (INIS)

Boeuf, J. P.; Pitchford, L. C.

2005-01-01

Non-equilibrium or non-thermal plasmas operate at low gas temperatures and this property make these plasmas very attractive in a number of applications, from etching and deposition in the microelectronics industry to plasma displays and pollution control. However, although it is quite easy to generate a large volume non-equilibrium plasma at pressure on the order or below 100 Pa, this is more of a challenge around atmospheric pressure. Large area plasma sources operating at atmospheric pressure represent a very cost-effective solution for material processing, light sources and other applications, and a large research effort has been devoted to the development of such sources in the last ten years. Dielectric Barrier Discharges (DBDs), where one or both electrodes are covered with a dielectric layer are good candidates for atmospheric non-equilibrium plasma generation because of their ability to limit the current and power deposition. It is also much easier to control an atmospheric discharge in a small volume. Therefore an atmospheric plasma source often consists of a number of micro-discharges arranged in a way that depends on the application. Even in DBDs with large electrode areas, the plasma is generally not uniform and consists in a large number of micro-discharges or filaments. In this lecture we present a discussion of the physical properties of non-equilibrium plasmas generated in different configurations and operating at atmospheric pressure. This discussion is based on results from numerical models and simulations of Dielectric Barrier Discharges to Micro-Hollow Cathode Discharges. We then focus on specific applications such as surface DBDs for flow control. These discharges (which have some similarities with the surface micro-discharges used in Plasma Display Panels) are being studied for their ability to modify the properties of the boundary layer along airfoils and hence to control the transition between laminar and turbulent regimes. We will show how

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

Science.gov (United States)

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

2015-10-01

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

Powerful highly efficient KrF lamps excited by surface and barrier discharges

International Nuclear Information System (INIS)

Borisov, V M; Vodchits, V A; El'tsov, A V; Khristoforov, O B

1998-01-01

An investigation was made of the characteristics of KrF lamps with different types of excitation by surface and barrier discharges in which the dielectric material was sapphire. The conditions were determined for the attainment of an extremely high yield of the KrF* fluorescence with the internal efficiency η in ∼30 % and 22% for pulsed surface and barrier discharges, respectively. A homogeneous surface discharge was maintained without gas circulation when the pulse repetition rate was 5 x 10 4 Hz. Quasicontinuous excitation of a surface discharge at near-atmospheric pressure made it possible to reach a KrF* fluorescence power density of about 80 W cm -3 , which was close to the limit set by the kinetics of the gaseous medium. Under prolonged excitation conditions the intensity of the UV output radiation was limited by the permissible heating of the gas to a temperature above which the operating life of the gaseous mixture containing fluorine fell steeply. This was the reason for the advantage of surface over barrier discharges: the former were characterised by a high thermal conductivity of a thin (∼0.2 mm) plasma layer on the surface of the cooled dielectric, which made it possible to construct powerful highly efficient KrF and ArF lamps emitting UV radiation of up to 1 W cm -2 intensity. (laser system components)

Dielectric barrier discharge in a two-phase mixture

Energy Technology Data Exchange (ETDEWEB)

Ye Qizheng; Zhang Ting; Lu Fei; Li Jin; He Zhenghao; Lin Fuchang [College of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

2008-01-21

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

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

NARCIS (Netherlands)

De Bie, C.; Martens, T.; Dijk, van J.; Paulussen, S.; Verheyde, B.; Corthals, S.; Bogaerts, A.

2011-01-01

The conversion of methane to value-added chemicals and fuels is considered to be one of the challenges of the 21st century. In this paper we study, by means of fluid modeling, the conversion of methane to higher hydrocarbons or oxygenates by partial oxidation with CO 2 or O 2 in a dielectric barrier

Conductivity of ion dielectrics during the mean flux-density electron- and X-ray pulse radiation

International Nuclear Information System (INIS)

Vajsburd, D.I.; Mesyats, G.A.; Naminov, V.L.; Tavanov, Eh.G.

1982-01-01

Conductivity of ion dielectrics under electron and X-ray pulse radiation is investigated. Investigations have been conducted in the range of average beam densities in which extinction of low-energy conductivity takes place. Thin plates of alkali-halogen crystals have been used as samples. Small-dimensional accelerator with controlled beam parameters: 1-20 ns, 0.1-2000 A/cm 2 , 0.3-0.5 MeV has been used for radiation. Temperature dependence of conductivity current pulse is determined. Time resolution of 10 - 10 s is achieved. In the 70-300 K range it practically coincides with radiation pulse. An essential inertial constituent is observed below 300 K. It is shown that at average beam densities a comparable contribution into fast conductivity is made by intracentre conductivity independent of temperature and high-temperature conductivity which decreases with temperature with activation energy equal to the energy of short-wave background. That is why amplitude of fast constituent decreases with temperature slower than high-energy conductivity

Cellulose Triacetate Dielectric Films For Capacitors

Science.gov (United States)

Yen, Shiao-Ping S.; Jow, T. Richard

1994-01-01

Cellulose triacetate investigated for use as dielectric material in high-energy-density capacitors for pulsed-electrical-power systems. Films of cellulose triacetate metalized on one or both sides for use as substrates for electrodes and/or as dielectrics between electrodes in capacitors. Used without metalization as simple dielectric films. Advantages include high breakdown strength and self-healing capability.

Circularly polarized antennas for active holographic imaging through barriers

Science.gov (United States)

McMakin, Douglas L [Richland, WA; Severtsen, Ronald H [Richland, WA; Lechelt, Wayne M [West Richland, WA; Prince, James M [Kennewick, WA

2011-07-26

Circularly-polarized antennas and their methods of use for active holographic imaging through barriers. The antennas are dielectrically loaded to optimally match the dielectric constant of the barrier through which images are to be produced. The dielectric loading helps to remove barrier-front surface reflections and to couple electromagnetic energy into the barrier.

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

International Nuclear Information System (INIS)

Gibalov, Valentin I.; Pietsch, Gerhard J.

2000-01-01

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

Degradation of anionic surfactants using the reactor based on dielectric barrier discharge

Directory of Open Access Journals (Sweden)

Aonyas Munera Mustafa

2016-01-01

Full Text Available Two anionic surfactants (sodium lauryl sulfate - SDS and sodium dodecylbenzenesulfonate - SDBS were treated with dielectric barrier discharge. Loss of surfactant activity, decrease of chemical oxygen demand and total organic carbon as well as lower toxicity of degradation products were determined. Effects of catalysts - hydrogen peroxide and iron (II, on parameters mentioned above, were determined. Catalysts affect the degradation of SDBS and in the case of SDS catalysts have no effect on degradation. Both catalysts induce the decrease of COD and TOC values. Toxicity of solutions after the plasma treatment is lower in all the systems tested. [Projekat Ministarstva nauke Republike Srbije, br. OI 172030

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

DEFF Research Database (Denmark)

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

2005-01-01

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

A dielectric barrier discharge in neon at atmospheric pressure

International Nuclear Information System (INIS)

Ran Junxia; Luo Haiyun; Wang Xinxin

2011-01-01

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

Two-dimensional plasma photonic crystals in dielectric barrier discharge

International Nuclear Information System (INIS)

Fan Weili; Dong Lifang; Zhang Xinchun

2010-01-01

A series of two-dimensional plasma photonic crystals have been obtained by filaments' self-organization in atmospheric dielectric barrier discharge with two water electrodes, which undergo the transition from square to square superlattice and finally to the hexagon. The spatio-temporal behaviors of the plasma photonic crystals in nanosecond scale have been studied by optical method, which show that the plasma photonic crystal is actually an integration of different transient sublattices. The photonic band diagrams of the transverse electric (TE) mode and transverse magnetic mode for each sublattice of these plasma photonic crystals have been investigated theoretically. A wide complete band gap is formed in the hexagonal plasma photonic crystal with the TE mode. The changes of the band edge frequencies and the band gap widths in the evolvement of different structures are studied. A kind of tunable plasma photonic crystal which can be controlled both in space and time is suggested.

GaN MOSHEMT employing HfO2 as a gate dielectric with partially etched barrier

Science.gov (United States)

Han, Kefeng; Zhu, Lin

2017-09-01

In order to suppress the gate leakage current of a GaN high electron mobility transistor (GaN HEMT), a GaN metal-oxide-semiconductor high electron mobility transistor (MOSHEMT) is proposed, in which a metal-oxide-semiconductor gate with high-dielectric-constant HfO2 as an insulating dielectric is employed to replace the traditional GaN HEMT Schottky gate. A 0.5 μm gate length GaN MOSHEMT was fabricated based on the proposed structure, the {{{Al}}}0.28{{{Ga}}}0.72{{N}} barrier layer is partially etched to produce a higher transconductance without deteriorating the transport characteristics of the two-dimensional electron gas in the channel, the gate dielectric is HfO2 deposited by atomic layer deposition. Current-voltage characteristics and radio frequency characteristics are obtained after device preparation, the maximum current density of the device is 900 mA mm-1, the source-drain breakdown voltage is 75 V, gate current is significantly suppressed and the forward gate voltage swing range is about ten times higher than traditional GaN HEMTs, the GaN MOSHEMT also demonstrates radio frequency characteristics comparable to traditional GaN HEMTs with the same gate length.

Electrolyte creepage barrier for liquid electrolyte fuel cells

Science.gov (United States)

Li, Jian [Alberta, CA; Farooque, Mohammad [Danbury, CT; Yuh, Chao-Yi [New Milford, CT

2008-01-22

A dielectric assembly for electrically insulating a manifold or other component from a liquid electrolyte fuel cell stack wherein the dielectric assembly includes a substantially impermeable dielectric member over which electrolyte is able to flow and a barrier adjacent the dielectric member and having a porosity of less than 50% and greater than 10% so that the barrier is able to measurably absorb and chemically react with the liquid electrolyte flowing on the dielectric member to form solid products which are stable in the liquid electrolyte. In this way, the barrier inhibits flow or creepage of electrolyte from the dielectric member to the manifold or component to be electrically insulated from the fuel cell stack by the dielectric assembly.

Recent developments in large-scale ozone generation with dielectric barrier discharges

Science.gov (United States)

Lopez, Jose L.

2014-10-01

Large-scale ozone generation for industrial applications has been entirely based on the creation of microplasmas or microdischarges created using dielectric barrier discharge (DBD) reactors. Although versions of DBD generated ozone have been in continuous use for over a hundred years especially in water treatment, recent changes in environmental awareness and sustainability have lead to a surge of ozone generating facilities throughout the world. As a result of this enhanced global usage of this environmental cleaning application various new discoveries have emerged in the science and technology of ozone generation. This presentation will describe some of the most recent breakthrough developments in large-scale ozone generation while further addressing some of the current scientific and engineering challenges of this technology.

High-efficiency removal of NOx using dielectric barrier discharge nonthermal plasma with water as an outer electrode

Science.gov (United States)

Dan, ZHAO; Feng, YU; Amin, ZHOU; Cunhua, MA; Bin, DAI

2018-01-01

With the rapid increase in the number of cars and the development of industry, nitrogen oxide (NOx) emissions have become a serious and pressing problem. This work reports on the development of a water-cooled dielectric barrier discharge reactor for gaseous NOx removal at low temperature. The characteristics of the reactor are evaluated with and without packing of the reaction tube with 2 mm diameter dielectric beads composed of glass, ZnO, MnO2, ZrO2, or Fe2O3. It is found that the use of a water-cooled tube reduces the temperature, which stabilizes the reaction, and provides a much greater NO conversion efficiency (28.8%) than that obtained using quartz tube (14.1%) at a frequency of 8 kHz with an input voltage of 6.8 kV. Furthermore, under equivalent conditions, packing the reactor tube with glass beads greatly increases the NO conversion efficiency to 95.85%. This is because the dielectric beads alter the distribution of the electric field due to the influence of polarization at the glass bead surfaces, which ultimately enhances the plasma discharge intensity. The presence of the dielectric beads increases the gas residence time within the reactor. Experimental verification and a theoretical basis are provided for the industrial application of the proposed plasma NO removal process employing dielectric bead packing.

A Numerical Study of the Sour Gas Reforming in a Dielectric Barrier Discharge Reactor

Directory of Open Access Journals (Sweden)

Sajedeh Shahsavari

2016-10-01

Full Text Available In this paper, using a one-dimensional simulation model, the reforming process of sour gas, i.e. CH4, CO2, and H2S, to the various charged particles and syngas in a dielectric barrier discharge (DBD reactor is studied. An electric field is applied across the reactor radius, and thus a non-thermal plasma discharge is formed within the reactor. Based on the space-time coupled finite element method, the governing equations are solved, and the temporal and spatial profiles of different formed charged species from sour gas inside the plasma reactor are verified. It is observed that the electric field increases radially towards the cathode electrode. Moreover, the electron density growth rate at the radial positions closer to the cathode surface is smaller than the one in the anode electrode region. Furthermore, as time progresses, the positive ions density near the anode electrode is higher. In addition, the produced syngas density is mainly concentrated in the proximity of anode dielectric electrode.

Laser amplification in excited dielectrics

Science.gov (United States)

Winkler, Thomas; Haahr-Lillevang, Lasse; Sarpe, Cristian; Zielinski, Bastian; Götte, Nadine; Senftleben, Arne; Balling, Peter; Baumert, Thomas

2018-01-01

Wide-bandgap dielectrics such as glasses or water are transparent at visible and infrared wavelengths. This changes when they are exposed to ultrashort and highly intense laser pulses. Different interaction mechanisms lead to the appearance of various transient nonlinear optical phenomena. Using these, the optical properties of dielectrics can be controlled from the transparent to the metal-like state. Here we expand this range by a yet unexplored mechanism in excited dielectrics: amplification. In a two-colour pump-probe experiment, we show that a 400 nm femtosecond laser pulse is coherently amplified inside an excited sapphire sample on a scale of a few micrometres. Simulations strongly support the proposed two-photon stimulated emission process, which is temporally and spatially controllable. Consequently, we expect applications in all fields that demand strongly localized amplification.

Lattices of dielectric resonators

CERN Document Server

Trubin, Alexander

2016-01-01

This book provides the analytical theory of complex systems composed of a large number of high-Q dielectric resonators. Spherical and cylindrical dielectric resonators with inferior and also whispering gallery oscillations allocated in various lattices are considered. A new approach to S-matrix parameter calculations based on perturbation theory of Maxwell equations, developed for a number of high-Q dielectric bodies, is introduced. All physical relationships are obtained in analytical form and are suitable for further computations. Essential attention is given to a new unified formalism of the description of scattering processes. The general scattering task for coupled eigen oscillations of the whole system of dielectric resonators is described. The equations for the  expansion coefficients are explained in an applicable way. The temporal Green functions for the dielectric resonator are presented. The scattering process of short pulses in dielectric filter structures, dielectric antennas  and lattices of d...

Pulsed electrical discharge in gas bubbles in water

Science.gov (United States)

Gershman, Sophia

A phenomenological picture of pulsed electrical discharge in gas bubbles in water is produced by combining electrical, spectroscopic, and imaging methods. The discharge is generated by applying one microsecond long 5 to 20 kilovolt pulses between the needle and disk electrodes submerged in water. A gas bubble is generated at the tip of the needle electrode. The study includes detailed experimental investigation of the discharge in argon bubbles and a brief look at the discharge in oxygen bubbles. Imaging, electrical characteristics, and time-resolved optical emission data point to a fast streamer propagation mechanism and formation of a plasma channel in the bubble. Spectroscopic methods based on line intensity ratios and Boltzmann plots of line intensities of argon, atomic hydrogen, and argon ions and the examination of molecular emission bands from molecular nitrogen and hydroxyl radicals provide evidence of both fast beam-like electrons and slow thermalized ones with temperatures of 0.6 -- 0.8 electron-volts. The collisional nature of plasma at atmospheric pressure affects the decay rates of optical emission. Spectroscopic study of rotational-vibrational bands of hydroxyl radical and molecular nitrogen gives vibrational and rotational excitation temperatures of the discharge of about 0.9 and 0.1 electron-volt, respectively. Imaging and electrical evidence show that discharge charge is deposited on the bubble wall and water serves as a dielectric barrier for the field strength and time scales of this experiment. Comparing the electrical and imaging information for consecutive pulses applied at a frequency of 1 Hz indicates that each discharge proceeds as an entirely new process with no memory of the previous discharge aside from long-lived chemical species, such as ozone and oxygen. Intermediate values for the discharge gap and pulse duration, low repetition rate, and unidirectional character of the applied voltage pulses make the discharge process here unique

Study of spatiotemporal dynamics of a nanosecond atmospheric-pressure dielectric barrier discharge in millimeter-long air gaps

Energy Technology Data Exchange (ETDEWEB)

Malashin, M. V.; Moshkunkov, S. I.; Khomich, V. Yu.; Shershunova, E. A., E-mail: eshershunova@gmail.com [Russian Academy of Sciences, Institute for Electrophysics and Electric Power (Russian Federation)

2017-02-15

The spatiotemporal dynamics of a nanosecond atmospheric-pressure dielectric barrier discharge in 1- to 3-mm-long air gaps was studied experimentally. By using a segmented electrode, data on the time evolution of the discharge in different regions of the discharge gap were obtained. The uniformity of the discharge over the cross section is estimated by analyzing the spatial distribution of its glow.

Evaluation of a new dielectric barrier discharge excitation source for the determination of arsenic with atomic emission spectrometry.

Science.gov (United States)

Zhu, Zhenli; He, Haiyang; He, Dong; Zheng, Hongtao; Zhang, Caixiang; Hu, Shenghong

2014-05-01

A low power dielectric barrier discharge excitation source was developed to determine arsenic in a cost-effective manner. Arsenic in water was reduced to AsH₃ by hydride generation (HG), which was transported to the miniature dielectric barrier discharge (DBD) excitation source for excitation and optical detection at As 193.7 nm atomic line. The DBD source consists of a quartz tube, a tungsten rod electrode, and a copper coil electrode. The main operation parameters and the potential interferences affecting the determination were investigated. The detection limit for arsenic with the proposed DBD-AES was 4.8 μg L(-1) when the HG products were dried with concentrated H₂SO₄ before introducing to DBD. Repeatability, expressed as the relative standard deviation of the spectral peak height, was 2.8% (n=11) for 0.1 mg L(-1) arsenic solution. The proposed method was successfully applied to the determinations of certified reference material (GBW08605) and nature water samples. Copyright © 2014 Elsevier B.V. All rights reserved.

[Study on formation process of honeycomb pattern in dielectric barrier discharge by optical emission spectrum].

Science.gov (United States)

Dong, Li-Fang; Zhu, Ping; Yang, Jing; Zhang, Yu

2014-04-01

The authors report on the first investigation of the variations in the plasma parameters in the formation process of the honeycomb pattern in a dielectric barrier discharge by optical emission spectrum in argon and air mixture. The discharge undergoes hexagonal lattice, concentric spot-ring pattern and honeycomb pattern with the applied voltage increasing. The molecular vibration temperature, electron excitation temperature and electronic density of the three kinds of patterns were investigated by the emission spectra of nitrogen band of second positive system (C3pi(u) --> B3 pi(g)), the relative intensity ratio method of spectral lines of Ar I 763.51 nm (2P(6) --> 1S(5)) and Ar I 772.42 nm (2P(2) -->1S(3)) and the broadening of spectral line 696.5 nm respectively. It was found that the molecular vibration temperature and electron excitation temperature of the honeycomb pattern are higher than those of the hexagonal lattice, but the electron density of the former is lower than that of the latter. The discharge powers of the patterns were also measured with the capacitance method. The discharge power of the honeycomb pattern is much higher than that of the hexagonal lattice. These results are of great importance to the formation mechanism of the patterns in dielectric barrier discharge.

Penetration of a dielectric barrier discharge plasma into textile structures at medium pressure

International Nuclear Information System (INIS)

Geyter, N De; Morent, R; Leys, C

2006-01-01

Plasma treatment of textiles is becoming more and more popular as a surface modification technique. Plasma treatment changes the outermost layer of a material without interfering with the bulk properties. However, textiles are several millimetres thick and need to be treated homogeneously throughout the entire thickness. To control the penetration depth of the plasma effect, it is necessary to study the influence of operating parameters. Three layers of a 100% polyester non-woven are treated in the medium pressure range (0.3-7 kPa) with a dielectric barrier discharge to study the influence of pressure and treatment time. Current and voltage waveforms and Lichtenberg figures are used to characterize the discharge. Process pressure proved to have an important effect on the penetration of the plasma through the textile layers. This is caused not only by the pressure dependence of diffusive transport of textile modifying particles but also by a different behaviour of the barrier discharge

Improving uniformity of atmospheric-pressure dielectric barrier discharges using dual frequency excitation

Science.gov (United States)

Liu, Y.; Peeters, F. J. J.; Starostin, S. A.; van de Sanden, M. C. M.; de Vries, H. W.

2018-01-01

This letter reports a novel approach to improve the uniformity of atmospheric-pressure dielectric barrier discharges using a dual-frequency excitation consisting of a low frequency (LF) at 200 kHz and a radio frequency (RF) at 13.56 MHz. It is shown that due to the periodic oscillation of the RF electric field, the electron acceleration and thus the gas ionization is temporally modulated, i.e. enhanced and suppressed during each RF cycle. As a result, the discharge development is slowed down with a lower amplitude and a longer duration of the LF discharge current. Hence, the RF electric field facilitates improved stability and uniformity simultaneously allowing a higher input power.

Laser-induced damage in dielectrics with nanosecond to subpicosecond pulses. I. Experimental. Part 1

International Nuclear Information System (INIS)

Stuart, B.C.; Herman, S.; Perry, M.D.

1994-12-01

The authors report extensive laser-induced damage threshold measurements on pure and multilayer dielectrics at 1053 and 526 mm for pulse durations, τ, ranging from 140 fs to 1 ns. Qualitative differences in the morphology of damage and a departure from the diffusion-dominated τ 1/2 scaling indicate that damage results from plasma formation and ablation for τ≤10 ps and from conventional melting and boiling for τ>50 ps. A theoretical model based on electron production via multiphoton ionization, Joule heating, and collisional (avalanche) ionization is in good agreement with both the pulsewidth and wavelength scaling of experimental results

Robust, Flexible and Lightweight Dielectric Barrier Discharge Actuators Using Nanofoams/Aerogels

Science.gov (United States)

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

2015-01-01

Robust, flexible, lightweight, low profile enhanced performance dielectric barrier discharge actuators (plasma actuators) based on aerogels/nanofoams with controlled pore size and size distribution as well as pore shape. The plasma actuators offer high body force as well as high force to weight ratios (thrust density). The flexibility and mechanical robustness of the actuators allows them to be shaped to conform to the surface to which they are applied. Carbon nanotube (CNT) based electrodes serve to further decrease the weight and profile of the actuators while maintaining flexibility while insulating nano-inclusions in the matrix enable tailoring of the mechanical properties. Such actuators are required for flow control in aeronautics and moving machinery such as wind turbines, noise abatement in landing gear and rotary wing aircraft and other applications.

Application of Atmospheric Dielectric Barrier Discharge Plasma for Polyethylene Powder Modification

International Nuclear Information System (INIS)

Pichal, J.; Aubrecht, L.; Pichal, J.; Hladik, J.; Spatenka, P.; Spatenka, P.

2006-01-01

Paper refers about a novel plasma reactor exploiting the dielectric barrier discharge (DBD) burning in air at atmospheric pressure by ambient temperature and its usability tests. Test modifications were performed with the high density polyethylene powder Borealis CB 9155-01. Modification effect was evaluated by means of dynamic capillarity rising measurements. Tests proved significant powder capillarity changes. The existence of powder surface changes was also confirmed by ESCA tests. Modification aging effect was remarkably small, hence modification effect is very time stable. In comparison with other in literature described apparatus used for this purpose the plasma reactor is of a simple construction and needs no vacuum equipment. Its operation costs are low. Described plasma modification method seems to be an appropriate method for plasma modification of polyethylene powder on the industrial scale

Temporal symmetry of individual filaments in different spatial symmetry filaments pattern in a dielectric barrier discharge

International Nuclear Information System (INIS)

Dong, L. F.; Xiao, H.; Fan, W. L.; Yin, Z. Q.; Zhao, H. T.

2010-01-01

The temporal behavior of individual filament in different spatial symmetry filaments patterns in dielectric barrier discharge is investigated by using an optical method. A series of return maps of the discharge moments of individual filaments is given. It is found that the temporal symmetry of individual filament changes with the change of the spatial symmetry of filaments pattern as the applied voltage increases. The role of wall charges for this phenomenon is analyzed.

Analysis and development of numerical methodologies for simulation of flow control with dielectric barrier discharge actuators

OpenAIRE

Abdollahzadehsangroudi, Mohammadmahdi

2014-01-01

The aim of this thesis is to investigate and develop different numerical methodologies for modeling the Dielectric Barrier discharge (DBD) plasma actuators for flow control purposes. Two different modeling approaches were considered; one based on Plasma-fluid model and the other based on a phenomenological model. A three component Plasma fluid model based on the transport equations of charged particles was implemented in this thesis in OpenFOAM, using several techniques to redu...

Electrode/Dielectric Strip For High-Energy-Density Capacitor

Science.gov (United States)

Yen, Shiao-Ping S.

1994-01-01

Improved unitary electrode/dielectric strip serves as winding in high-energy-density capacitor in pulsed power supply. Offers combination of qualities essential for high energy density: high permittivity of dielectric layers, thinness, and high resistance to breakdown of dielectric at high electric fields. Capacitors with strip material not impregnated with liquid.

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

Science.gov (United States)

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

2017-01-01

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

Coherent structures induced by dielectric barrier discharge plasma actuator

Science.gov (United States)

Zhang, Xin; Li, Huaxing; Choi, Kwing So; Song, Longfei

2017-11-01

The structures of a flow field induced by a plasma actuator were investigated experimentally in quiescent air using high-speed Particle Image Velocimetry (PIV) technology. The motivation behind was to figure out the flow control mechanism of the plasma technique. A symmetrical Dielectric Barrier Discharge (DBD) plasma actuator was mounted on the suction side of the SC (2)-0714 supercritical airfoil. The results demonstrated that the plasma jet had some coherent structures in the separated shear layer and these structures were linked to a dominant frequency of f0 = 39 Hz when the peak-to-peak voltage of plasma actuator was 9.8 kV. The high speed PIV measurement of the induced airflow suggested that the plasma actuator could excite the flow instabilities which lead to production of the roll-up vortex. Analysis of transient results indicated that the roll-up vortices had the process of formation, movement, merging and breakdown. This could promote the entrainment effect of plasma actuator between the outside airflow and boundary layer flow, which is very important for flow control applications.

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

Science.gov (United States)

Hoskinson, Alan R.

2012-01-01

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

The formation of diffuse discharge by short-front nanosecond voltage pulses and the modification of dielectrics in this discharge

Science.gov (United States)

Orlovskii, V. M.; Panarin, V. A.; Shulepov, M. A.

2014-07-01

The dynamics of diffuse discharge formation under the action of nanosecond voltage pulses with short fronts (below 1 ns) in the absence of a source of additional preionization and the influence of a dielectric film on this process have been studied. It is established that the diffuse discharge is induced by the avalanche multiplication of charge initiated by high-energy electrons and then maintained due to secondary breakdowns propagating via ionized gas channels. If a dielectric film (polyethylene, Lavsan, etc.) is placed on the anode, then multiply repeated discharge will lead to surface and bulk modification of the film material. Discharge-treated polyethylene film exhibits a change in the optical absorption spectrum in the near-IR range.

Dielectric barrier discharge atmospheric cold plasma inhibits Escherichia coli 0157:H7, Salmonella, Listeria monocytogenes, and Tulane virus in Romaine lettuce

Science.gov (United States)

The present study investigated the effects of dielectric barrier discharge atmospheric cold plasma (DACP) treatment on the inactivation of Escherichia coli O157:H7, Salmonella, Listeria monocytogenes, and Tulane virus (TV) on Romaine lettuce, assessing the influences of moisture vaporization, modifi...

Erratum to 'Surface Modification of PBO Fibers for Composites by Coaxial Atmospheric Dielectric Barrier Discharge (PLA-PLA)'

International Nuclear Information System (INIS)

2013-01-01

There is a mistake in the funding number (National Natural Science Foundation of China (No. 10875146)) of article Surface Modification of PBO Fibers for Composites by Coaxial Atmospheric Dielectric Barrier Discharge (PLA-PLA), written by HU Qianqian, XU Jinzhou, ZHOU Zhenxing, ZHANG Jing, published in Plasma Science and Technology, 2013, Vol. 15, Issue 5, page number 429, it should be corrected as National Natural Science Foundation of China (No. 11075033). (erratum)

Electrical and chemical properties of XeCl*(308 nm) exciplex lamp created by a dielectric barrier discharge

International Nuclear Information System (INIS)

Baadj, S.; Harrache, Z.; Belasri, A.

2013-01-01

The aim of this work is to highlight, through numerical modeling, the chemical and the electrical characteristics of xenon chloride mixture in XeCl* (308 nm) excimer lamp created by a dielectric barrier discharge. A temporal model, based on the Xe/Cl 2 mixture chemistry, the circuit and the Boltzmann equations, is constructed. The effects of operating voltage, Cl 2 percentage in the Xe/Cl 2 gas mixture, dielectric capacitance, as well as gas pressure on the 308-nm photon generation, under typical experimental operating conditions, have been investigated and discussed. The importance of charged and excited species, including the major electronic and ionic processes, is also demonstrated. The present calculations show clearly that the model predicts the optimal operating conditions and describes the electrical and chemical properties of the XeCl* exciplex lamp

Electrical and chemical properties of XeCl*(308 nm) exciplex lamp created by a dielectric barrier discharge

Science.gov (United States)

Baadj, S.; Harrache, Z.; Belasri, A.

2013-12-01

The aim of this work is to highlight, through numerical modeling, the chemical and the electrical characteristics of xenon chloride mixture in XeCl* (308 nm) excimer lamp created by a dielectric barrier discharge. A temporal model, based on the Xe/Cl2 mixture chemistry, the circuit and the Boltzmann equations, is constructed. The effects of operating voltage, Cl2 percentage in the Xe/Cl2 gas mixture, dielectric capacitance, as well as gas pressure on the 308-nm photon generation, under typical experimental operating conditions, have been investigated and discussed. The importance of charged and excited species, including the major electronic and ionic processes, is also demonstrated. The present calculations show clearly that the model predicts the optimal operating conditions and describes the electrical and chemical properties of the XeCl* exciplex lamp.

Trace determination of antimony by hydride generation atomic absorption spectrometry with analyte preconcentration/atomization in a dielectric barrier discharge atomizer

Czech Academy of Sciences Publication Activity Database

Zurynková, Pavla; Dědina, Jiří; Kratzer, Jan

2018-01-01

Roč. 1010, JUN (2018), s. 11-19 ISSN 0003-2670 R&D Projects: GA ČR GA14-23532S Institutional support: RVO:68081715 Keywords : dielectric barrier discharge * Stibane * atomization and preconcentration Subject RIV: CB - Analytical Chemistry, Separation OBOR OECD: Analytical chemistry Impact factor: 4.950, year: 2016

Electromagnetic Pulse Generated by a Horizontal Electric Dipole over a Perfect Conductor Covered with a Dielectric Layer

Directory of Open Access Journals (Sweden)

Zheng Juan

2018-01-01

Full Text Available In this paper, the electromagnetic pulse due to a delta-function current excitation has been derived on the planar surface of a perfect conductor coated by a dielectric layer. The approximate expression of wave component is obtained when both the transmitting source and the receiving antennas are located on the surface of the dielectric. When the thickness of the intermediate layer is subjected to the condition of k1l<<0.6, this physical model is applied to the microstrip circuit. Analysis and computations of the wave components are carried out on the microstrip circuit, including the surface trapped wave vector which had been ignored in former studies. It is shown that the trapped-surface-wave terms should have been taken into consideration as the main contribution in total transient field in the far-field radiations.

Surface modification for biomedical purposes utilizing dielectric barrier discharges at atmospheric pressure

Energy Technology Data Exchange (ETDEWEB)

Gessner, Cordula; Bartels, Volker; Betker, Tanja; Matucha, Ulrike; Penache, Cristina; Klages, Claus-Peter

2004-07-01

Using dielectric barrier discharges (DBD) at atmospheric pressure, glass or polymer surfaces were equipped with epoxide groups or amino groups by plasma deposition from suitable monomers or - in case of polymers - DBD treatment in nitrogen-containing gases. Functional group densities have been estimated using absorption and fluorescence measurements or by X-ray photoelectron spectroscopy. Amino group densities are comparable or even larger than those of aminosilylated surfaces. Fluorescence-labeled streptavidin has been used to investigate the binding capacity of surfaces equipped with covalently bound biotin molecules, starting either from epoxide or from amino groups. As an example of a Plasma Printing process, the generation of an array amino-functionalized spots, 400-{mu}m in diameter on a polymer surface by local deposition from aminopropyl-trimethoxysilane is demonstrated.

Sterilization of Turmeric by Atmospheric Pressure Dielectric Barrier Discharge Plasma

Science.gov (United States)

Setareh, Salarieh; Davoud, Dorranian

2013-11-01

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

Sterilization of Turmeric by Atmospheric Pressure Dielectric Barrier Discharge Plasma

International Nuclear Information System (INIS)

Salarieh Setareh; Dorranian Davoud

2013-01-01

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/O 2 , He, and He/O 2 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/O 2 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

Electrical model of dielectric barrier discharge homogenous and filamentary modes

Science.gov (United States)

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.

Electrical model of dielectric barrier discharge homogenous and filamentary modes

International Nuclear Information System (INIS)

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. (paper)

Easy to implement diagnostics of a glow dielectric barrier discharge

International Nuclear Information System (INIS)

Massines, F.; Segur, P.

2001-01-01

It is relatively easier to generate plasma at atmospheric pressure rather than low pressure. In retaliation, due to the short mean free path of different particles, the diagnostics giving microscopic characteristics are more difficult to implement. This, for example, is the case of Langmuir probe or mass spectrometry although solutions have been put forward. Likewise, the strong contribution of the excited state quenching can render optical characterization result interpretation difficult. Nevertheless, there are easy to implement basic diagnostics like optical emission spectroscopy, the ultra rapid photography or the discharge current measurement. A possible approach to get to the microscopic data consists in associating the experimental results with the results of a numerical model. This is the approach undertaken for the study of a glow dielectric barrier discharge (DBD) and is described in the following text in order to illustrate the possibilities of those easy to implement diagnostics supported by the analysis of surfaces having interacted with the plasma

Optimization of Industrial Ozone Generation with Pulsed Power

Science.gov (United States)

Lopez, Jose; Guerrero, Daniel; Freilich, Alfred; Ramoino, Luca; Seton Hall University Team; Degremont Technologies-Ozonia Team

2013-09-01

Ozone (O3) is widely used for applications ranging from various industrial chemical synthesis processes to large-scale water treatment. The consequent surge in world-wide demand has brought about the requirement for ozone generation at the rate of several hundreds grams per kilowatt hour (g/kWh). For many years, ozone has been generated by means of dielectric barrier discharges (DBD), where a high-energy electric field between two electrodes separated by a dielectric and gap containing pure oxygen or air produce various microplasmas. The resultant microplasmas provide sufficient energy to dissociate the oxygen molecules while allowing the proper energetics channels for the formation of ozone. This presentation will review the current power schemes used for large-scale ozone generation and explore the use of high-voltage nanosecond pulses with reduced electric fields. The created microplasmas in a high reduced electric field are expected to be more efficient for ozone generation. This is confirmed with the current results of this work which observed that the efficiency of ozone generation increases by over eight time when the rise time and pulse duration are shortened. Department of Physics, South Orange, NJ, USA.

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

International Nuclear Information System (INIS)

Tashima, Daisuke; Yoshitama, Hiromu; Sakoda, Tatsuya; Okazaki, Akihito; Kawaji, Takayuki

2012-01-01

Highlights: ► The specific capacitance of the EDLCs could be improved by oxygen plasma treatment. ► 15 s treated EDLCs showed a 20% increase in capacitance relative to untreated EDLCs. ► The plasma treatment yields EDLCs that are suitable for high-energy applications. - Abstract: The electrochemical properties of electric double-layer capacitors (EDLCs) made with plasma-treated powdered activated carbon (treated using a dielectric barrier discharge) were examined using cyclic voltammetry (CV), Cole–Cole plots, and X-ray photoelectron spectroscopy (XPS). The dielectric barrier discharge method, which operates at atmospheric pressure, dramatically reduces the processing time and does not require vacuum equipment, making it a more practical alternative than low-pressure plasma treatment. The experimental data indicate that the specific capacitance of the EDLCs could be improved by oxygen plasma treatment. Capacitance of EDLCs made with activated carbon treated for 15 s showed 193.5 F/g that 20% increase in the specific capacitance relative to untreated EDLCs. This result indicates that the plasma treatment yields EDLCs that are suitable for high-energy applications. The enhancement of capacitance was mainly attributed to an increase in the BET surface area of the activated carbon and the creation of carboxyl groups on the surface of the carbon. The carboxyl groups induced oxidation–reduction reactions in the presence of O 2 which was included in the operation gas. In addition, the carboxyl groups improved the penetration of the electrolyte solution into the carbon electrodes.

Influence of oxygen concentration on ethylene removal using dielectric barrier discharge

Science.gov (United States)

Takahashi, Katsuyuki; Motodate, Takuma; Takaki, Koichi; Koide, Shoji

2018-01-01

Ethylene gas is decomposed using a dielectric barrier discharge plasma reactor for long-period preservation of fruits and vegetables. The oxygen concentration in ambient gas is varied from 2 to 20% to simulate the fruit and vegetable transport container. The experimental results show that the efficiency of ethylene gas decomposition increases with decreasing oxygen concentration. The reactions of ethylene molecules with ozone are analyzed by Fourier transform infrared spectrometry. The analysis results show that the oxidization process by ozone is later than that by oxygen atoms. The amount of oxygen atoms that contribute to ethylene removal increases with decreasing oxygen concentration because the reaction between oxygen radicals and oxygen molecules is suppressed at low oxygen concentrations. Ozone is completely removed and the energy efficiency of C2H4 removal is increased using manganese dioxide as a catalyst.

Ultraviolet-B radiation enhancement in dielectric barrier discharge based xenon chloride exciplex source by air

Energy Technology Data Exchange (ETDEWEB)

Gulati, P., E-mail: pgulati1512@gmail.com [CSIR-Central Electronics Engineering Research Institute (CSIR-CEERI), Pilani, Rajasthan-333031 (India); Department of Physics, Banasthali University, P.O. Banasthali Vidyapith, Rajasthan 304022 (India); Prakash, R.; Pal, U. N.; Kumar, M. [CSIR-Central Electronics Engineering Research Institute (CSIR-CEERI), Pilani, Rajasthan-333031 (India); Vyas, V. [Department of Physics, Banasthali University, P.O. Banasthali Vidyapith, Rajasthan 304022 (India)

2014-07-07

A single barrier dielectric barrier discharge tube of quartz with multi-strip Titanium-Gold (Ti-Au) coatings have been developed and utilized for ultraviolet-B (UV-B) radiation production peaking at wavelength 308 nm. The observed radiation at this wavelength has been examined for the mixtures of the Xenon together with chlorine and air admixtures. The gas mixture composition, chlorine gas content, total gas pressure, and air pressure dependency of the UV intensity, has been analyzed. It is found that the larger concentration of Cl{sub 2} deteriorates the performance of the developed source and around 2% Cl{sub 2} in this source produced optimum results. Furthermore, an addition of air in the xenon and chlorine working gas environment leads to achieve same intensity of UV-B light but at lower working gas pressure where significant amount of gas is air.

Ultraviolet-B radiation enhancement in dielectric barrier discharge based xenon chloride exciplex source by air

Science.gov (United States)

Gulati, P.; Prakash, R.; Pal, U. N.; Kumar, M.; Vyas, V.

2014-07-01

A single barrier dielectric barrier discharge tube of quartz with multi-strip Titanium-Gold (Ti-Au) coatings have been developed and utilized for ultraviolet-B (UV-B) radiation production peaking at wavelength 308 nm. The observed radiation at this wavelength has been examined for the mixtures of the Xenon together with chlorine and air admixtures. The gas mixture composition, chlorine gas content, total gas pressure, and air pressure dependency of the UV intensity, has been analyzed. It is found that the larger concentration of Cl2 deteriorates the performance of the developed source and around 2% Cl2 in this source produced optimum results. Furthermore, an addition of air in the xenon and chlorine working gas environment leads to achieve same intensity of UV-B light but at lower working gas pressure where significant amount of gas is air.

Water-dielectric-breakdown relation for the design of large-area multimegavolt pulsed-power systems

Directory of Open Access Journals (Sweden)

W. A. Stygar

2006-07-01

Full Text Available We have developed an empirical electrical-breakdown relation that can be used to design large-area water-insulated pulsed-power systems. Such systems often form an integral part of multiterawatt pulsed-power accelerators, and may be incorporated in future petawatt-class machines. We find that complete dielectric failure is likely to occur in water between a significantly field-enhanced anode and a less-enhanced cathode when E_{p}τ_{eff}^{0.330±0.026}=0.135±0.009. In this expression E_{p}≡V_{p}/d is the peak value in time of the spatially averaged electric field between the anode and cathode (in MV/cm, V_{p} is the peak voltage across the electrodes, d is the distance between the anode and cathode, and τ_{eff} is the temporal width (in μs of the voltage pulse at 63% of peak. This relation is based on 25 measurements for which 1≤V_{p}≤4.10   MV, 1.25≤d≤22   cm, and 0.011≤τ_{eff}≤0.6   μs. The normalized standard deviation of the differences between these measurements and the associated predictions of the relation is 12%.

Radiation effects of electromagnetic pulses on mouse blood-testis barrier

International Nuclear Information System (INIS)

Hou Wugang; Zhao Jie; Zhang Yuanqiang

2005-01-01

Radiation effects caused by 100 kV/m and 400 kV/m electromagnetic pulse (EMP) irradiations on mouse blood-testis barrier were studied by means of routine HE staining, Lanthanum traced electron microscope and injection of caudal vein with Evans Blue. The EMP irradiation of different dose rates damaged Sertoli's cell and blood-testis barrier of mouse testis in different levels. Severe injuries were observed with the 400 kV/m irradiation group, with apoptosis and necrosis in a large quantity of the spermatogenic cells, shape and structural changes of the Sertoli's cells, and serious injuries to the blood-testis barrier, one day after the irradiation. The basal compartment separated from the adluminal compartment in most of the VIII stage seminiferous epithelium, and a great number of apoptosis and necrosis spermatogenic cells were released into the cavities. Injuries of blood-testis barrier could be observed 21 days after the 400 kV/m irradiation. The injuries of 100 kV/m irradiation groups were less severe than the 400 kV/m groups, in which the damages to the Sertoli's cells, the seminiferous epithelium and blood-testis barrier recovered to some extent 14 days after the irradiation. The authors conclude that EMP irradiation can damage mouse blood-tests barrier. The injuries, and the time for recovery, are related to EMP power intensity. (authors)

Comparison of three dielectric barrier discharges regarding their physical characteristics and influence on the adhesion properties on maple, high density fiberboards and wood plastic composite

International Nuclear Information System (INIS)

Peters, F; Wieneke, S; Ohms, G; Viöl, W; Hünnekens, B; Militz, H

2017-01-01

In this study, three different dielectric barrier discharges, based on the same setup and run with the same power supply, are characterized by emission spectroscopy with regards to the reduced electrical field strength, and the rotational, vibrational and electron temperature. To compare discharges common for the treatment on wood, a coplanar surface barrier discharge, a direct dielectric barrier discharge and a jet system/remote plasma are chosen. To minimize influences due to the setups or power, the discharges are realized with the same electrodes and power supply and normalized to the same power. To evaluate the efficiency of the different discharges and the influence on treated materials, the surface free energy is determined on a maple wood, high density fiberboard and wood plastic composite. The influence is measured depending on the treatment time, with the highest impact in the time of 5 s. (paper)

Comparison of three dielectric barrier discharges regarding their physical characteristics and influence on the adhesion properties on maple, high density fiberboards and wood plastic composite

Science.gov (United States)

Peters, F.; Hünnekens, B.; Wieneke, S.; Militz, H.; Ohms, G.; Viöl, W.

2017-11-01

In this study, three different dielectric barrier discharges, based on the same setup and run with the same power supply, are characterized by emission spectroscopy with regards to the reduced electrical field strength, and the rotational, vibrational and electron temperature. To compare discharges common for the treatment on wood, a coplanar surface barrier discharge, a direct dielectric barrier discharge and a jet system/remote plasma are chosen. To minimize influences due to the setups or power, the discharges are realized with the same electrodes and power supply and normalized to the same power. To evaluate the efficiency of the different discharges and the influence on treated materials, the surface free energy is determined on a maple wood, high density fiberboard and wood plastic composite. The influence is measured depending on the treatment time, with the highest impact in the time of 5 s.

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

Czech Academy of Sciences Publication Activity Database

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

2014-01-01

Roč. 86, č. 19 (2014), s. 9620-9625 ISSN 0003-2700 Grant - others:GA AV ČR(CZ) M200311202 Institutional support: RVO:68081715 Keywords : dielectric barrier discharge * hydride generation * atomic absorption spectrometry Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 5.636, year: 2014

Electrical and chemical properties of XeCl*(308 nm) exciplex lamp created by a dielectric barrier discharge

Energy Technology Data Exchange (ETDEWEB)

Baadj, S.; Harrache, Z., E-mail: zharrache@yahoo.com; Belasri, A. [Université des Sciences et de la Technologie d’Oran, USTO-MB, Laboratoire de Physique des Plasmas, Matériaux Conducteurs et leurs Application (LPPMCA) (Algeria)

2013-12-15

The aim of this work is to highlight, through numerical modeling, the chemical and the electrical characteristics of xenon chloride mixture in XeCl* (308 nm) excimer lamp created by a dielectric barrier discharge. A temporal model, based on the Xe/Cl{sub 2} mixture chemistry, the circuit and the Boltzmann equations, is constructed. The effects of operating voltage, Cl{sub 2} percentage in the Xe/Cl{sub 2} gas mixture, dielectric capacitance, as well as gas pressure on the 308-nm photon generation, under typical experimental operating conditions, have been investigated and discussed. The importance of charged and excited species, including the major electronic and ionic processes, is also demonstrated. The present calculations show clearly that the model predicts the optimal operating conditions and describes the electrical and chemical properties of the XeCl* exciplex lamp.

Characterization of a dielectric barrier discharge in controlled atmosphere

Science.gov (United States)

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'.

High tension generator for corona barrier discharge

International Nuclear Information System (INIS)

Baltag, O.; Costandache, D.; Gheorghiu, M.; Paraschivescu, A.; Popa, G.

2001-01-01

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

A kinetic study of ozone and nitric oxides in dielectric barrier discharges for O2/NOx mixtures

International Nuclear Information System (INIS)

Sun Jizhong; Stirner, T.; Wang Dezhen

2002-01-01

A simple model is described to simulate kinetic processes in dielectric barrier discharges for O 2 /NO x mixtures. A threshold of ozone production found experimentally is confirmed by the calculations of this modeling, and the underlying chemical reaction mechanisms are discussed. It is also found that the effects of diffusion processes in the period of the lifetime of O atoms are not important to micro-discharge channels with a large radius, i.e. larger than 150 μm

Plasmachemical and heterogeneous processes in ozonizers with oxygen activation by a dielectric barrier discharge

Energy Technology Data Exchange (ETDEWEB)

Mankelevich, Yu. A., E-mail: ymankelevich@mics.msu.su; Voronina, E. N.; Poroykov, A. Yu.; Rakhimov, T. V.; Voloshin, D. G.; Chukalovsky, A. A. [Moscow State University, Skobeltsyn Institute of Nuclear Physics (Russian Federation)

2016-10-15

Plasmachemical and heterogeneous processes of generation and loss of ozone in the atmosphericpressure dielectric barrier discharge in oxygen are studied theoretically. Plasmachemical and electronic kinetics in the stage of development and decay of a single plasma filament (microdischarge) are calculated numerically with and without allowance for the effects of ozone vibrational excitation and high initial ozone concentration. The developed analytical approach is applied to determine the output ozone concentration taking into account ozone heterogeneous losses on the Al{sub 2}O{sub 3} dielectric surface. Using the results of quantummechanical calculations by the method of density functional theory, a multistage catalytic mechanism of heterogeneous ozone loss based on the initial passivation of a pure Al{sub 2}O{sub 3} surface by ozone and the subsequent interaction of O{sub 3} molecules with the passivated surface is proposed. It is shown that the conversion reaction 2O{sub 3} → 3O{sub 2} of a gas-phase ozone molecule with a physically adsorbed ozone molecule can result in the saturation of the maximum achievable ozone concentration at high specific energy depositions, the nonstationarity of the output ozone concentration, and its dependence on the prehistory of ozonizer operation.

Spatially and temporally resolved detection of arsenic in a capillary dielectric barrier discharge by hydride generation high-resolved optical emission spectrometry

Czech Academy of Sciences Publication Activity Database

Burhenn, S.; Kratzer, Jan; Svoboda, Milan; Klute, F. D.; Michels, A.; Veža, D.; Franzke, J.

2018-01-01

Roč. 90, MAR (2018), s. 3424-3429 ISSN 0003-2700 R&D Projects: GA ČR GA17-04329S Institutional support: RVO:68081715 Keywords : dielectric barrier discharge * optical emission spectroscopy * arsenic hydride Subject RIV: CB - Analytical Chemistry , Separation OBOR OECD: Analytical chemistry Impact factor: 6.320, year: 2016

Spatially and temporally resolved detection of arsenic in a capillary dielectric barrier discharge by hydride generation high-resolved optical emission spectrometry

Czech Academy of Sciences Publication Activity Database

Burhenn, S.; Kratzer, Jan; Svoboda, Milan; Klute, F. D.; Michels, A.; Veža, D.; Franzke, J.

2018-01-01

Roč. 90, MAR (2018), s. 3424-3429 ISSN 0003-2700 R&D Projects: GA ČR GA17-04329S Institutional support: RVO:68081715 Keywords : dielectric barrier discharge * optical emission spectroscopy * arsenic hydride Subject RIV: CB - Analytical Chemistry, Separation OBOR OECD: Analytical chemistry Impact factor: 6.320, year: 2016

Gene Transfection Method Using Atmospheric Pressure Dielectric-Barrier Discharge Plasmas

Science.gov (United States)

Sasaki, Shota; Kanzaki, Makoto; Kaneko, Toshiro

2013-09-01

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

Treatment of Wastewater by Ozone Produced in Dielectric Barrier Discharge

Directory of Open Access Journals (Sweden)

Rita Bhatta

2015-01-01

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

Radial Distribution of the Nanosecond Dielectric Barrier Discharge Current in Atmospheric-Pressure Air

Science.gov (United States)

Malashin, M. V.; Moshkunov, S. I.; Khomich, V. Yu.; Shershunova, E. A.

2018-01-01

Experimental results on the radial distribution of the nanosecond dielectric barrier discharge (DBD) current in flat millimeter air gaps under atmospheric pressure and natural humidity of 40-60% at a voltage rise rate at the electrodes of 250 V/ns are presented. The time delay of the appearance of discharge currents was observed to increase from the center to the periphery of the air gap at discharge gap heights above 3 mm, which correlated with the appearance of constricted channels against the background of the volume DBD plasma. Based on the criterion of the avalanche-streamer transition, it is found out that the development of a nanosecond DBD in air gaps of 1-3 mm occurs by the streamer mechanism.

Methane from benzene in argon dielectric barrier discharge

International Nuclear Information System (INIS)

Das, Tomi Nath; Dey, G.R.

2013-01-01

Highlights: ► Efficient on-line conversion of benzene to methane at room temperature. ► Absence of other H-atom donor suggests new type of chemistry. ► For parent loss > 90%, methane yield was ∼40% of limit due to H-atom availability. ► Surface moisture contributed ·OH radical for trace phenolic products’ formation. ► This method may emerge as an exploitable tactic for pollutants’ usable alterations. -- Abstract: A first-time account of direct, on-line, instantaneous and efficient chemical conversion of gas phase benzene to methane in argon Dielectric Barrier Discharge (DBD) is presented. In the absence of another overt hydrogen-donating source, potency of analogous parents toward methane generation is found to follow the order: benzene > toluene > p-xylene. Simultaneous production of trace amounts of phenolic surface deposits suggest (a) prompt decomposition of the parent molecules, including a large fraction yielding atomic transients (H-atom), (b) continuous and appropriate recombination of such parts, and (c) trace moisture in parent contributing ·OH radicals and additional H-atoms, which suitably react with the unreacted fraction of the parent, and also other intermediates. Results highlight Ar DBD to be a simple and exploitable technology for transforming undesirable hazardous aromatics to usable/useful low molecular weight open-chain products following the principles of green chemistry and engineering

Experimental installation for excitation of semiconductors and dielectrics by picosecond pulsed electron beam and electric field

International Nuclear Information System (INIS)

Nasibov, A.S.; Berezhnoj, K.V.; Shapkin, P.V.; Reutova, A.G.; Shunajlov, S.A.; Yalandin, M.I.

2009-01-01

The experimental facility for shaping high-voltage pulses with amplitudes of 30-250 kV and durations of 100-500 ps and electron beams with a current density of up to 1000 A/cm -2 is described. The facility was built using the principle of energy compression of a pulse from a nanosecond high-voltage generator accompanied by the subsequent pulse sharpening and cutting. The setup is equipped with two test coaxial chambers for radiation excitation in semiconductor crystals by an electron beam or an electric field in air at atmospheric pressure and T = 300 K. Generation of laser radiation in the visible range under field and electron pumping was attained in ZnSSe, ZnSe, ZnCdS, and CdS (462, 480, 515, and 525 nm, respectively). Under the exposure to an electric field (up to 10 6 V x cm -1 ), the laser generation region is as large as 300-500 μm. The radiation divergence was within 5 Deg C. The maximum integral radiation power (6 kW at λ = 480 nm) was obtained under field pumping of a zinc selenide sample with a single dielectric mirror [ru

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

KAUST Repository

Zhang, Xuming

2015-01-01

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

Measurements of water molecule density by tunable diode laser absorption spectroscopy in dielectric barrier discharges with gas-water interface

Science.gov (United States)

Tachibana, Kunihide; Nakamura, Toshihiro; Kawasaki, Mitsuo; Morita, Tatsuo; Umekawa, Toyofumi; Kawasaki, Masahiro

2018-01-01

We measured water molecule (H2O) density by tunable diode-laser absorption spectroscopy (TDLAS) for applications in dielectric barrier discharges (DBDs) with a gas-water interface. First, the effects of water temperature and presence of gas flow were tested using a Petri dish filled with water and a gas injection nozzle. Second, the TDLAS system was applied to the measurements of H2O density in two types of DBDs; one was a normal (non-inverted) type with a dielectric-covered electrode above a water-filled counter electrode and the other was an inverted type with a water-suspending mesh electrode above a dielectric-covered counter electrode. The H2O density in the normal DBD was close to the density estimated from the saturated vapor pressure, whereas the density in the inverted DBD was about half of that in the former type. The difference is attributed to the upward gas flow in the latter type, that pushes the water molecules up towards the gas-water interface.

Spatio-temporal dynamics of the white-eye square superlattice pattern in dielectric barrier discharge

International Nuclear Information System (INIS)

Wei, Lingyan; Dong, Lifang; Feng, Jianyu; Liu, Weibo; Fan, Weili; Pan, Yuyang

2016-01-01

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. (paper)

Barrier discharge. The transferred charge and ozone synthesis

International Nuclear Information System (INIS)

Gibalov, V.I.; Samoilovich, V.G.

1991-01-01

We have undertaken an experimental investigation of the influence of the conditions of barrier discharge implementation such as: the discharge gap value, the type of gas, and the polarity and dielectric permittivity of the dielectric electrode on the value of charge transferred in a micro-discharge. It is shown that the increase in the specific capacitance of the electrodes leads to proportional increase in the transferred charge value, reaching 100-200 nC in a discharge gap 1 mm, in air. In this case the amplitude and duration of a current pulse in the microdischarge reach, respectively, 10 to 15 A and 40 ns. It is also demonstrated that in air with increase in the discharge gap value one can observe a decrease in the efficiency of the ozone synthesis whereas in oxygen there exists a more complicated dependence: the maximum of efficiency is observed at a discharge gap value of 0.7 to 1.0 mm. (orig.)

Characterization and modelling of low-pressure rf discharges at 2-500 MHz for miniature alkali vapour dielectric barrier discharge lamps

International Nuclear Information System (INIS)

Venkatraman, Vinu; Shea, Herbert; Pétremand, Yves; Rooij, Nico de

2012-01-01

Low-pressure dielectric barrier discharge (DBD) alkali vapour lamps are of particular interest for portable atomic clocks because they (1) could enable low-power operation, (2) generate the precise required wavelength, (3) are planar simplifying chip-level integration and (4) use external electrodes, which increases the lifetime. Given the stringent requirements on lamps for atomic clocks, it is important to identify the parameters that can be optimized to meet these performance requirements (size, power consumption, stability, reliability). We report on the electrical and optical characteristics of dielectric barrier plasma discharges observed in two configurations: (1) in a vacuum chamber over a wide low-pressure range (2-100 mbar) for three different buffer gases (He, Ar, N 2 ) driven at different frequencies between 2 and 500 MHz and (2) on microfabricated hermetically sealed Rb vapour cells filled with 30 and 70 mbar of Ar. We discuss the optimum conditions for a low-power and stable operation of a Rb vapour DBD lamp, aimed at chip-scale atomic clocks. We also present the electrical modelling of the discharge parameters to understand the power distribution mechanisms and the input power to discharge power coupling efficiency.

Numerical Modelling of Mutual Effect among Nearby Needles in a Multi-Needle Configuration of an Atmospheric Air Dielectric Barrier Discharge

Directory of Open Access Journals (Sweden)

Xiaoxing Zhang

2012-05-01

Full Text Available A numerical study has been conducted to understand the mutual effect among nearby needles in a multi-needle electrode dielectric barrier discharge. In the present paper, a fluid-hydrodynamic model is adopted. In this model, the mutual effect among nearby needles in a multi-needle configuration of an atmospheric air dielectric barrier discharge are investigated using a fluid-hydrodynamic model including the continuity equations for electrons and positive and negative ions coupled with Poisson’s equation. The electric fields at the streamer head of the middle needle (MN and the side needles (SNs in a three-needle model decreased under the influence of the mutual effects of nearby needles compared with that in the single-needle model. In addition, from the same comparison, the average propagation velocities of the streamers from MN and SNs, the electron average energy profile of MN and SNs (including those in the streamer channel, at the streamer head, and in the unbridged gap, and the electron densities at the streamer head of the MN and SNs also decreased. The results obtained in the current paper agreed well with the experimental and simulation results in the literature.

Plasma induced degradation of Indigo Carmine by bipolar pulsed dielectric barrier discharge(DBD) in the water-air mixture.

Science.gov (United States)

Zhang, Ruo-Bing; Wu, Yan; Li, Guo-Feng; Wang, Ning-Hui; Li, Jie

2004-01-01

Degradation of the Indigo Carmine (IC) by the bipolar pulsed DBD in water-air mixture was studied. Effects of various parameters such as gas flow rate, solution conductivity, pulse repetitive rate and ect., on color removal efficiency of dying wastewater were investigated. Concentrations of gas phase o3 and aqueous phase H2O2 under various conditions were measured. Experimental results showed that air bubbling facilitates the breakdown of water and promotes generation of chemically active species. Color removal efficiency of IC solution can be greatly improved by the air aeration under various solution conductivities. Decolorization efficiency increases with the increase of the gas flow rate, and decreases with the increase of the initial solution conductivity. A higher pulse repetitive rate and a larger pulse capacitor C(p) are favorable for the decolorization process. Ozone and hydrogen peroxide formed decreases with the increase of initial solution conductivity. In addition, preliminary analysis of the decolorization mechanisms is given.

The Influence of Relative Humidity on Dielectric Barrier Discharge Plasma Flow Control Actuator Performance

Science.gov (United States)

Wicks, M.; Thomas, F. O.; Corke, T. C.; Patel, M.

2012-11-01

Dielectric barrier discharge (DBD) plasma actuators possess numerous advantages for flow control applications and have been the focus of several previous studies. Most work has been performed in relatively pristine laboratory settings. In actual flow control applications, however, it is essential to assess the impact of various environmental influences on actuator performance. As a first effort toward assessing a broad range of environmental effects on DBD actuator performance, the influence of relative humidity (RH) is considered. Actuator performance is quantified by force balance measurements of reactive thrust while RH is systematically varied via an ultrasonic humidifier. The DBD plasma actuator assembly, force balance, and ultrasonic humidifier are all contained inside a large, closed test chamber instrumented with RH and temperature sensors in order to accurately estimate the average RH at the actuator. Measurements of DBD actuator thrust as a function of RH for several different applied voltage regimes and dielectric materials and thicknesses are presented. Based on these results, several important design recommendations are made. This work was supported by Innovative Technology Applications Company (ITAC), LLC under a Small Business Innovation Research (SBIR) Phase II Contract No. N00014-11-C-0267 issued by the U.S. Department of the Navy.

Indoor air purification by dielectric barrier discharge combined with ionic wind: physical and microbiological investigations

Science.gov (United States)

Timmermann, E.; Prehn, F.; Schmidt, M.; Höft, H.; Brandenburg, R.; Kettlitz, M.

2018-04-01

A non-thermal plasma source based on a surface dielectric barrier discharge (DBD) is developed for purification of recirculating air in operating theatres in hospitals. This is a challenging application due to high flow rates, short treatment times and the low threshold for ozone in the ventilated air. Therefore, the surface DBD was enhanced in order to generate an ionic wind, which can deflect and thus, filter out airborne microorganisms. Electrical and gas diagnostics as well as microbiological experiments were performed in a downscaled plasma source under variation of various electrical parameters, but application-oriented airflow velocity and humidity. The dependence of electrical power and ozone concentration as well as charged particles in the plasma treated air on frequency, voltage and relative humidity is presented and discussed. The presence of humidity causes a more conductive dielectric surface and thus a weaker plasma formation, especially at low frequency. The airborne test bacteria, Escherichia coli, showed significant effect to plasma treatment (up to 20% reduction) and to plasma with ionic wind (up to 90% removal); especially a configuration with 70% removal and an accompanying ozone concentration of only 360 ppb is promising for future application.

Modeling of a Ne/Xe dielectric barrier discharge excilamp for improvement of VUV radiation production

Science.gov (United States)

Khodja, K.; Belasri, A.; Loukil, H.

2017-08-01

This work is devoted to excimer lamp efficiency optimization by using a homogenous discharge model of a dielectric barrier discharge in a Ne-Xe mixture. The model includes the plasma chemistry, electrical circuit, and Boltzmann equation. In this paper, we are particularly interested in the electrical and kinetic properties and light output generated by the DBD. Xenon is chosen for its high luminescence in the range of vacuum UV radiation around 173 nm. Our study is motivated by interest in this type of discharge in many industrial applications, including the achievement of high light output lamps. In this work, we used an applied sinusoidal voltage, frequency, gas pressure, and concentration in the ranges of 2-8 kV, 10-200 kHz, 100-800 Torr, and 10-50%, respectively. The analyzed results concern the voltage V p across the gap, the dielectric voltage V d, the discharge current I, and the particles densities. We also investigated the effect of the electric parameters and xenon concentration on the lamp efficiency. This investigation will allow one to find out the appropriate parameters for Ne/Xe DBD excilamps to improve their efficiency.

Speed of streamers in argon over a flat surface of a dielectric

Energy Technology Data Exchange (ETDEWEB)

Sobota, A; Kramer, N J; Van Veldhuizen, E M; Stoffels, W W; Haverlag, M [Eindhoven University of Technology, Department of Applied Physics, PO Box 513, 5600MB Eindhoven (Netherlands); Lebouvier, A [Ecole Polytechnique de l' Universite d' Orleans, 12 rue de Blois, BP 6744, 45067 Orleans Cedex 2 (France); Manders, F [Advanced Development Lighting, Philips Lighting, Mathildelaan 1, 5611 BD, Eindhoven (Netherlands)], E-mail: a.sobota@tue.nl

2009-01-07

A pin-pin electrode geometry was used to study the velocities of streamers propagating over a flat dielectric surface and in gas close to the dielectric. The experiments were done in an argon atmosphere, at pressures from 0.1 to 1 bar, with repetitive voltage pulses. The dielectric surface played a noticeable role in discharge ignition and propagation. The average speed of the discharge decreased with higher pressure and lower voltage pulse rise rate. It was higher when the conductive channel between the electrodes was formed over the dielectric, rather than through the gas. Space resolved measurements revealed an increase in velocity of the discharge as it travelled towards the grounded electrode.

Speed of streamers in argon over a flat surface of a dielectric

International Nuclear Information System (INIS)

Sobota, A; Kramer, N J; Van Veldhuizen, E M; Stoffels, W W; Haverlag, M; Lebouvier, A; Manders, F

2009-01-01

A pin-pin electrode geometry was used to study the velocities of streamers propagating over a flat dielectric surface and in gas close to the dielectric. The experiments were done in an argon atmosphere, at pressures from 0.1 to 1 bar, with repetitive voltage pulses. The dielectric surface played a noticeable role in discharge ignition and propagation. The average speed of the discharge decreased with higher pressure and lower voltage pulse rise rate. It was higher when the conductive channel between the electrodes was formed over the dielectric, rather than through the gas. Space resolved measurements revealed an increase in velocity of the discharge as it travelled towards the grounded electrode.

Frequency Dependent Electrical and Dielectric Properties of Au/P3HT:PCBM:F4-TCNQ/n-Si Schottky Barrier Diode

Science.gov (United States)

Taşçıoğlu, İ.; Tüzün Özmen, Ö.; Şağban, H. M.; Yağlıoğlu, E.; Altındal, Ş.

2017-04-01

In this study, poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester: 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (P3HT:PCBM:F4-TCNQ) organic film was deposited on n-type silicon (n-Si) substrate by spin coating method. The electrical and dielectric analysis of Au/P3HT:PCBM:F4-TCNQ/n-Si Schottky barrier diode was conducted by means of capacitance-voltage ( C- V) and conductance-voltage ( G/ ω- V) measurements in the frequency range of 10 kHz-2 MHz. The C- V- f plots exhibit fairly large frequency dispersion due to excess capacitance caused by the presence of interface states ( N ss). The values of N ss located in semiconductor bandgap at the organic film/semiconductor interface were calculated by Hill-Coleman method. Experimental results show that dielectric constant ( ɛ') and dielectric loss ( ɛ″) decrease with increasing frequency, whereas loss tangent (tan δ) remains nearly the same. The decrease in ɛ' and ɛ″ was interpreted by the theory of dielectric relaxation due to interfacial polarization. It is also observed that ac electrical conductivity ( σ ac) and electric modulus ( M' and M″) increase with increasing frequency.

Nonlinear behavior in the time domain in argon atmospheric dielectric-barrier discharges

International Nuclear Information System (INIS)

Shi Hong; Wang Yanhui; Wang Dezhen

2008-01-01

A vast majority of nonlinear behavior in atmospheric pressure discharges has so far been studied in the space domain, and their time-domain characters are often believed to exact the periodicity of the externally applied voltage. In this paper, based on one-dimensional fluid mode, we study complex nonlinear behavior in the time domain in argon atmospheric dielectric-barrier discharges at very broad frequency range from kilohertz to megahertz. Under certain conditions, the discharge not only can be driven to chaos from time-periodic state through period-doubling bifurcation, but also can return stable periodic motion from chaotic state through an inverse period-doubling bifurcation sequence. Upon changing the parameter the discharge undergoes alternatively chaotic and periodic behavior. Some periodic windows embedded in chaos, as well as the secondary bifurcation occurring in the periodic windows can also be observed. The corresponding discharge characteristics are investigated.

Regeneration of nitrobenzene-exhausted granular activated carbon by dielectric barrier discharge method

International Nuclear Information System (INIS)

Lan, Tian; Gao, Wenli; Li, Zhongjian; Lei, Lecheng

2013-01-01

A novel method for the regeneration of nitrobenzene-exhausted granular activated carbon using dielectric barrier discharge (DBD) was proposed in this study. The influence of several parameters including voltage, frequency, and plasma medium on the regeneration efficiency were studied. Under optimum conditions, regeneration efficiency can reach over 80% and remain nearly stable after 5 times of regeneration cycle. The texture characteristic and surface chemistry of Granular Activated Carbon (GAC) samples were also investigated. Analysis shows that the pore volume and specific surface area of regenerated GAC is strongly recovered compared to the exhausted GAC, but the discharge can cause some pores to diminish. Acidic functional groups on GAC's surface especially carboxylic groups had a growing tendency after DBD process. Experimental results show that the regeneration of GAC by DBD method mainly attributes to high active species and thermal effect, while O 3 has minor effect.

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

International Nuclear Information System (INIS)

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

2016-01-01

Highlights: • We fabricated polyvinyl alcohol/malonic acid nanofibers using electrospinning. • The surface nanofibers were modified by gaseous (air, nitrogen, CO_2 and argon) dielectric barrier discharge. • Among them, air plasma had the most significant effect on glucose oxidase immobilization. • Chemical analysis showed that after modification of nanofibers by air plasma, the carboxyl group increased. • After air plasma treatment, reusability and storage stability of glucose oxidase immobilized on nanofibers improved. - Abstract: Polymeric nanofiber prepares a suitable situation for enzyme immobilization for variety of applications. In this research, we have fabricated polyvinyl alcohol (PVA)/malonic acid nanofibers using electrospinning. After fabrication of nanofibers, the effect of air, nitrogen, CO_2, and argon DBD (dielectric barrier discharge) plasmas on PVA/malonic acid nanofibers were analysed. Among them, air plasma had the most significant effect on glucose oxidase (GOx) immobilization. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectrum analysis and X-ray photoelectron spectroscopy (XPS) results revealed that in case of air plasma modified nanofibers, the carboxyl groups on the surface are increased. The scanning electron microscopy (SEM) images showed that, after GOx immobilization, the modified nanofibers with plasma has retained its nanofiber structure. Finally, we analysed reusability and storage stability of GOx immobilized on plasma modified and unmodified nanofibers. The results were more satisfactory for modified nanofibers with respect to unmodified ones.

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-11-01

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

Plasma treatment of polyethylene tubes in continuous regime using surface dielectric barrier discharge with water electrodes

Science.gov (United States)

Galmiz, Oleksandr; Zemánek, Miroslav; Pavliňák, David; Černák, Mirko

2018-05-01

Combining the surface dielectric barrier discharges generated in contact with water based electrolytes, as the discharge electrodes, we have designed a new type of surface electric discharge, generating thin layers of plasma which propagate along the treated polymer surfaces. The technique was aimed to achieve uniform atmospheric pressure plasma treatment of polymeric tubes and other hollow bodies. The results presented in this work show the possibility of such system to treat outer surface of polymer materials in a continuous mode. The technical details of experimental setup are discussed as well as results of treatment of polyethylene tubes are shown.

Enhanced accumulation of U(VI) by Aspergillus oryzae mutant generated by dielectric barrier discharge air plasma

International Nuclear Information System (INIS)

Wencheng Song; North China Electric Power University, Beijing; Xiangxue Wang; Soochow University, Suzhou; Wen Tao; Hongqing Wang; Tasawar Hayat; Quaid-I-Azam University, Islamabad; Xiangke Wang; Soochow University, Suzhou; King Abdulaziz University, Jeddah

2016-01-01

Aspergillus oryzae was isolated from radionuclides' contaminated soils, and dielectric barrier discharge plasma was used to mutate A. oryzae to improve bioremediation capability of U(VI) pollution. The maximum accumulation capacities of U(VI) on mutated A.oryzae was 627.4 mg/g at T = 298 K and pH = 5.5, which was approximately twice than that of raw A.oryzae. XPS analysis indicated that U(VI) accumulation on mutated A. oryzae was largely attributable to nitrogen- and oxygen-containing functional groups on fungal mycelia. The mutated A. oryzae can be harnessed as bioremediation agents for radionuclides pollution. (author)

The Influence of Gas Composition in Dielectric Barrier Discharges on the Broadening of the Hydrogen Hα Transition

International Nuclear Information System (INIS)

Janus, H. W.

2006-01-01

The distribution of hydrogen atoms responsible for emission of the Balmer Hα line in the region of the dielectric barrier discharges in the helium and hydrogen as well as in the argon and hydrogen mixtures, in the direction perpendicular to the electrode surfaces, has bee determined by the optical emission spectroscopy accounting for the polarization of the emitted light. The procedure of fitting the measured line profiles accounting for the Stark effect has been used for determination of the distribution of the electric field in the discharge region

Abatement of malodorants from pesticide factory in dielectric barrier discharges

International Nuclear Information System (INIS)

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

2010-01-01

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 5.20 mg/kJ.

Degradation of diuron in aqueous solution by dielectric barrier discharge

Energy Technology Data Exchange (ETDEWEB)

Feng Jingwei [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment Nanjing University, Nanjing 210093 (China); Zheng Zheng [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment Nanjing University, Nanjing 210093 (China)], E-mail: zzheng@nju.edu.cn; Sun Yabing; Luan Jingfei; Wang Zhen; Wang Lianhong; Feng Jianfang [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment Nanjing University, Nanjing 210093 (China)

2008-06-15

Degradation of diuron in aqueous solution was conducted in a dielectric barrier discharge (DBD) reactor and the proposed degradation mechanism was investigated in detail. The factors that affect the degradation of diuron were examined. The degradation efficiency of diuron and the removal of total organic carbon (TOC) increased with increasing input power, and the degradation of diuron by DBD fitted first-order kinetics. Both strong acidic and alkaline solution conditions could improve diuron degradation efficiency and TOC removal rate. Degradation of diuron could be accelerated or inhibited in the presence of H{sub 2}O{sub 2} depending on the dosage. The degradation efficiency increased dramatically with adding Fe{sup 2+}. The removal of TOC and the amount of the detected Cl{sup -}, NO{sub 3}{sup -} and NH{sub 4}{sup +} were increased in the presence of Fe{sup 2+}. The concentrations of oxalic and acetic acids were almost the same in the absence and presence of Fe{sup 2+}, but high concentration of formic acid was accumulated in the presence of Fe{sup 2+}. The main degradation pathway of diuron by DBD involved a series of dechlorination-hydroxylation, dealkylation and oxidative opening of the aromatic ring processes.

Bluff Body Flow Control Using Dielectric Barrier Discharge Plasma Actuators

Science.gov (United States)

Thomas, Flint; Kozlov, Alexey

2008-11-01

The results of an experimental investigation involving the use of dielectric barrier discharge plasma actuators to control bluff body flow is presented. The motivation for the work is plasma landing gear noise control for commercial transport aircraft. For these flow control experiments, the cylinder in cross-flow is chosen for study since it represents a generic flow geometry that is similar in all essential aspects to a landing gear strut. The current work is aimed both at extending the plasma flow control concept to Reynolds numbers typical of landing approach and take-off and on the development of optimum plasma actuation strategies. The cylinder wake flow with and without actuation are documented in detail using particle image velocimetry (PIV) and constant temperature hot-wire anemometry. The experiments are performed over a Reynolds number range extending to ReD=10^5. Using either steady or unsteady plasma actuation, it is demonstrated that even at the highest Reynolds number Karman shedding is totally eliminated and turbulence levels in the wake decrease by more than 50%. By minimizing the unsteady flow separation from the cylinder and associated large-scale wake vorticity, the radiated aerodynamic noise is also reduced.

Interaction of current filaments in dielectric barrier discharges with relation to surface charge distributions

International Nuclear Information System (INIS)

Stollenwerk, L

2009-01-01

In a planar, laterally extended dielectric barrier discharge (DBD) system operated in glow mode, a filamentary discharge is observed. The filaments tend to move laterally and hence tend to cause collisions. Thereby, usually one collision partner becomes destroyed. In this paper, the collision process and especially the preceding time period is investigated. Beside the luminescence density of the filaments, the surface charge density accumulated between the single breakdowns of the DBD is observed via an optical measurement technique based on the linear electro-optical effect (pockels effect). A ring-like substructure of the surface charge distribution of a single filament is found, which correlates to the filament interaction behaviour. Furthermore, a preferred filament distance is found, suggesting the formation of a filamentary quasi-molecule.

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

Directory of Open Access Journals (Sweden)

Lukas JW Seidelmann

2017-03-01

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

Dielectric and magnetic characterizations of capacitor structures with an ionic liquid/MgO barrier and a ferromagnetic Pt electrode

Directory of Open Access Journals (Sweden)

D. Hayakawa

2016-11-01

Full Text Available The dielectric and magnetic properties of electric double layer (EDL capacitor structures with a perpendicularly magnetized Pt/Co/Pt electrode and an insulating cap layer (MgO are investigated. An electric field is applied through a mixed ionic liquid/MgO barrier to the surface of the top Pt layer, at which the magnetic moment is induced by the ferromagnetic proximity effect. The basic dielectric properties of the EDL capacitor are studied by varying the thickness of the MgO cap layer. The results indicate that the capacitance, i.e., the accumulated charge density at the Pt surface, is reduced with increasing the MgO thickness. From the MgO thickness dependence of the capacitance value, the effective dielectric constant of the ionic liquid is evaluated. Almost no electric field effect on the magnetic moment, the coercivity, or the Curie temperature is confirmed in the top Pt layer with the thickness of 1.3 nm, regardless of the presence or absence of the MgO cap layer, whereas the a clear change in the magnetic moment is observed when the top Pt layer is replaced by a Pd layer of 1.7 nm.

Conversion of methane to methanol in an ac dielectric barrier discharge

International Nuclear Information System (INIS)

Aghamir, F M; Matin, N S; Jalili, A H; Esfarayeni, M H; Khodagholi, M A; Ahmadi, R

2004-01-01

A dielectric barrier discharge (DBD) has been used to investigate the conversion of methane to methanol and higher hydrocarbons in ac non-equilibrium plasmas. Experiments were carried out at atmospheric pressure and ambient temperature. A non-equilibrium plasma was generated in a DBD reactor by applying a high voltage to the reactor electrodes. Activation of methane molecules led to the production of C 2 hydrocarbons and methanol. The effect of the applied voltage, residence time and feed mixture such as helium and oxygen on the methane conversion and product selectivity was studied. Helium appears to have no effect on the conversion and selectivity at our applied voltages. The methane conversion increases significantly on introduction of oxygen in the feed stream. Inclusion of oxygen leads to the formation of methanol. Our results show that production of methanol is initiated around an applied voltage of 12 kV and the conversion of methane increases with increasing voltage and residence time, while the product selectivity is independent of the applied voltage

Microwave and pulsed power engineering

International Nuclear Information System (INIS)

Hofer, W.W.

1984-01-01

The Microwave and Pulsed Power Engineering Thrust Area is responsible for developing the short-term and long-term engineering resources required to support the growing microwave and pulsed power engineering requirements of several LLNL Programs. The responsibility of this Thrust Area is to initiate applicable research and development projects and to provide capabilities and facilities to permit engineers involved in these and other programs to make significant contributions. In this section, the principal projects are described: dielectric failure prediction using partial discharge analysis, coating dielectrics to increase surface flashover potential, and the microwave generator experiment

Methane activation using Kr and Xe in a dielectric barrier discharge reactor

International Nuclear Information System (INIS)

Jo, Sungkwon; Lee, Dae Hoon; Kim, Kwan-Tae; Kang, Woo Seok; Song, Young-Hoon

2014-01-01

Methane has interested many researchers as a possible new energy source, but the high stability of methane causes a bottleneck in methane activation, limiting its practical utilization. To determine how to effectively activate methane using non-thermal plasma, the conversion of methane is measured in a planar-type dielectric barrier discharge reactor using three different noble gases—Ar, Kr, and Xe—as additives. In addition to the methane conversion results at various applied voltages, the discharge characteristics such as electron temperature and electron density were calculated through zero-dimensional calculations. Moreover, the threshold energies of excitation and ionization were used to distinguish the dominant particle for activating methane between electrons, excited atoms, and ionized atoms. From the experiments and calculations, the selection of the additive noble gas is found to affect not only the conversion of methane but also the selectivity of product gases even under similar electron temperature and electron density conditions

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

Science.gov (United States)

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...

Using a nitrogen dielectric barrier discharge for surface treatment

International Nuclear Information System (INIS)

Borcia, G; Anderson, C A; Brown, N M D

2005-01-01

In this paper, continuing previous work, we report on the installation and the testing of an experimental dielectric barrier discharge (DBD) reactor run in a controlled atmospheric pressure gaseous environment other than air. Here, the effects of a N 2 -DBD treatment on the surface of a test polymer material (UHMW polyethylene) are examined, reported, discussed and compared to results obtained previously following air-DBD treatment. Surface analysis and characterization were performed using x-ray photoelectron spectroscopy, contact angle measurement and scanning electron microscopy before and following the DBD processing described. The discharge parameters used were correlated with the changes in the surface characteristics found following DBD treatments of various durations in a nitrogen atmosphere. The work focuses on the control of the gaseous environment supporting the discharge and on the possibility of overcoming the potentially dominant effect of reactive oxygen-related species, derived from any residual air present. The results obtained underline the very high reactivity of such species in the discharge, but are encouraging in respect of the possibility of the implantation or generation of functional groups other than oxygen-related ones at the surface of interest. The processing conditions concerned simulate 'real' continuous high speed processing, allowing the planning of further experiments, where various gaseous mixtures of the type X + N 2 will be used for controlled surface functionalization

Manipulation of stored charge in anodic aluminium oxide/SiO2 dielectric stacks by the use of pulsed anodisation

International Nuclear Information System (INIS)

Lu, Zhong; Ouyang, Zi; Grant, Nicholas; Wan, Yimao; Yan, Di; Lennon, Alison

2016-01-01

Graphical abstract: - Highlights: • Pulse anodisation was used to grow AAO layers with controllable stored charge. • Stored charge density ranging from −5.2 × 10 11 to 2.5 × 10 12 q/cm 2 was demonstrated. • Enhancement in surface passivation was demonstrated with charge management. • Annealing significantly reduces the positive stored charge and the interface defect. - Abstract: A method of fabricating anodic aluminium oxide (AAO) with the capability of manipulating its stored charge is reported. This method involves the use of a pulsed current source to anodise aluminium layers instead of the typically used constant current/voltage source, with the test structures experiencing positive and negative cycles periodically. By tuning the positive cycle percentage, it is demonstrated that the effective stored charge density can be manipulated in a range from −5.2 × 10 11 to 2.5 × 10 12 q/cm 2 when the AAO is formed over a 12 nm SiO 2 layer. An investigation of the stored charge distribution in the dielectric stacks indicates a positive fixed charge at the SiO 2 /Si interface, a negative fixed charge at the AAO/SiO 2 interface and a positive bulk charge within the AAO layer. The effective stored charge density and interface states were found to be affected by annealing conditions and it is suggested that oxygen annealing can reduce the bulk positive charge while post-metallisation anneal is most effective in reducing silicon interface defects. Charge manipulation using pulsed anodisation is shown to reduce carrier recombination on boron-diffused silicon surfaces highlighting the potential of the process to be used to tune the electrical properties of dielectric layers so that they can reduce surface recombination on silicon surfaces having different dopant polarity and concentrations.

Dependence of Ozone Generation on Gas Temperature Distribution in AC Atmospheric Pressure Dielectric Barrier Discharge in Oxygen

Science.gov (United States)

Takahashi, Go; Akashi, Haruaki

AC atmospheric pressure multi-filament dielectric barrier discharge in oxygen has been simulated using two dimensional fluid model. In the discharge, three kinds of streamers have been obtained. They are primary streamers, small scale streamers and secondary streamers. The primary streamers are main streamers in the discharge and the small scale streamers are formed after the ceasing of the primary streamers. And the secondary streamers are formed on the trace of the primary streamers. In these streamers, the primary and the small scale streamers are very effective to generate O(3P) oxygen atoms which are precursor of ozone. And the ozone is generated mainly in the vicinity of the dielectrics. In high gas temperature region, ozone generation decreases in general. However, increase of the O(3P) oxygen atom density in high gas temperature region compensates decrease of ozone generation rate coefficient. As a result, amount of ozone generation has not changed. But if the effect of gas temperature was neglected, amount of ozone generation increases 10%.

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

Science.gov (United States)

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.

Comparison of precursors for pulsed metal-organic chemical vapor deposition of HfO2 high-K dielectric thin films

International Nuclear Information System (INIS)

Teren, Andrew R.; Thomas, Reji; He, Jiaqing; Ehrhart, Peter

2005-01-01

Hafnium oxide films were deposited on Si(100) substrates using pulsed metal-organic chemical vapor deposition (CVD) and evaluated for high-K dielectric applications. Three types of precursors were tested: two oxygenated ones, Hf butoxide-dmae and Hf butoxide-mmp, and an oxygen-free one, Hf diethyl-amide. Depositions were carried out in the temperature range of 350-650 deg. C, yielding different microstructures ranging from amorphous to crystalline, monoclinic, films. The films were compared on the basis of growth rate, phase development, density, interface characteristics, and electrical properties. Some specific features of the pulsed injection technique are considered. For low deposition temperatures the growth rate for the amide precursor was significantly higher than for the mixed butoxide precursors. A thickness-dependent amorphous to crystalline phase transition temperature was found for all precursors. There is an increase of the film density along with the deposition temperature from values as low as 5 g/cm 3 at 350 deg. C to values close to the bulk value of 9.7 g/cm 3 at 550 deg. C. Crystallization is observed in the same temperature range for films of typically 10-20 nm thickness. However, annealing studies show that this density increase is not simply related to the crystallization of the films. Similar electrical properties could be observed for all precursors and the dielectric constant of the films reaches values similar to the best values reported for bulk crystalline HfO 2

Tree-inception in PMMA with a barrier

International Nuclear Information System (INIS)

Gefle, O S; Lebedev, S M; Pokholkov, Y P; Gockenbach, E; Borsi, H

2004-01-01

The experimental results of a study of the tree-inception phenomenon for three-layer dielectrics in a divergent field are presented in this paper. It is shown that the tree-inception time depends on both the position of the high-permittivity barrier in the insulating gap and the ratio of the permittivities of the barrier material and main dielectric, and that it has a maximum at the optimal barrier position. It is found that the tree-inception length has a minimum value at this barrier position. Good agreement between the coefficient of the local field non-uniformity and the tree-inception time or the initial tree length was found

Atmospheric-pressure dielectric barrier discharge with capillary injection for gas-phase nanoparticle synthesis

International Nuclear Information System (INIS)

Ghosh, Souvik; Liu, Tianqi; Bilici, Mihai; Cole, Jonathan; Huang, I-Min; Sankaran, R Mohan; Staack, David; Mariotti, Davide

2015-01-01

We present an atmospheric-pressure dielectric barrier discharge (DBD) reactor for gas-phase nanoparticle synthesis. Nickel nanoparticles are synthesized by homogenous nucleation from nickelocene vapor and characterized online by aerosol mobility measurements. The effects of residence time and precursor concentration on particle growth are studied. We find that narrower distributions of smaller particles are produced by decreasing the precursor concentration, in agreement with vapor nucleation theory, but larger particles and aggregates form at higher gas flow rates where the mean residence time should be reduced, suggesting a cooling effect that leads to enhanced particle nucleation. In comparison, incorporating a capillary gas injector to alter the velocity profile is found to significantly reduce particle size and agglomeration. These results suggest that capillary gas injection is a better approach to decreasing the mean residence time and narrowing the residence time distribution for nanoparticle growth by producing a sharp and narrow velocity profile. (paper)

Hydrogen production by reforming of hydrocarbons and alcohols in a dielectric barrier discharge

Energy Technology Data Exchange (ETDEWEB)

Sarmiento, Belen; Brey, J. Javier; Viera, Inmaculada G. [Hynergreen Technologies, S.A. Avda. de la Buhaira, 2. 41018 Sevilla (Spain); Gonzalez-Elipe, Agustin R.; Cotrino, Jose; Rico, Victor J. [Instituto de Ciencia de los Materiales de Sevilla (CSIC-University Sevilla), Avda. Americo Vespucio, 49, 41092 Sevilla (Spain)

2007-06-10

This work reports about the use of plasmas to obtain hydrogen by reforming of hydrocarbons or alcohols in mixtures with CO{sub 2} or H{sub 2}O. The plasma is activated in a dielectric barrier discharge (DBD) reactor working at atmospheric pressure and low temperatures (i.e., about 100 C). The reactor presents a great versatility in operation and a low manufacturing cost. Results are presented for the reforming of methane, methanol and ethanol. Methane transforms up to a 70% into CO and H{sub 2} without formation of any kind of superior hydrocarbon. For the two alcohols 100% conversion into the same products is found for flows much higher than in the case of methane. The work reports a description of the reactor and the operational conditions of the power supply enabling the ignition of the plasma and its steady state operation. (author)

Numerical simulation of nanosecond-pulse electrical discharges

Science.gov (United States)

Poggie, J.; Adamovich, I.; Bisek, N.; Nishihara, M.

2013-02-01

Recent experiments with a nanosecond-pulse, dielectric barrier discharge at the stagnation point of a Mach 5 cylinder flow have demonstrated the formation of weak shock waves near the electrode edge, which propagate upstream and perturb the bow shock. This is a promising means of flow control, and understanding the detailed physics of the conversion of electrical energy into gas motion will aid in the design of efficient actuators based on the concept. In this work, a simplified configuration with planar symmetry was chosen as a vehicle to develop a physics-based model of nanosecond-pulse discharges, including realistic air kinetics, electron energy transport, and compressible bulk gas flow. A reduced plasma kinetic model (23 species and 50 processes) was developed to capture the dominant species and reactions for energy storage and thermalization in the discharge. The kinetic model included electronically and vibrationally excited species, and several species of ions and ground state neutrals. The governing equations included the Poisson equation for the electric potential, diffusion equations for each neutral species, conservation equations for each charged species, and mass-averaged conservation equations for the bulk gas flow. The results of calculations with this model highlighted the path of energy transfer in the discharge. At breakdown, the input electrical energy was transformed over a time scale on the order of 1 ns into chemical energy of ions, dissociation products, and vibrationally and electronically excited particles. About 30% of this energy was subsequently thermalized over a time scale of 10 µs. Since the thermalization time scale was faster than the acoustic time scale, the heat release led to the formation of weak shock waves originating near the sheath edge, consistent with experimental observations. The computed translational temperature rise (40 K) and nitrogen vibrational temperature rise (370 K) were of the same order of magnitude as

Dielectric and barrier thickness fluctuation scattering in Al2O3/AlGaN/GaN double heterojunction high-electron mobility transistors

International Nuclear Information System (INIS)

Ji, Dong; Lu, Yanwu; Liu, Bing; Liu, Guipeng; Zhu, Qinsheng; Wang, Zhanguo

2013-01-01

The two-dimensional electron gas (2DEG) mobility limited by dielectric and barrier thickness fluctuations (TF) scattering in Al 2 O 3 /AlGaN/GaN double heterojunction high-electron mobility transistors (HEMTs) is calculated. Calculation shows that thickness fluctuation scattering is the main limitation in Al 2 O 3 /AlGaN/GaN double heterojunction HEMTs with thin Al 2 O 3 layer thicknesses. In addition, a study of 2DEG mobility as a function of 2DEG density, n s , shows that TF scattering acts as the main limitation when n s exceeds 2 × 10 12 cm −2 . The results may be used to design HEMTs to obtain higher 2DEG mobilities by modulating the dielectric layer and barrier thicknesses or 2DEG density. - Highlights: • The mobility limited by thickness fluctuation (TF) scattering is studied. • Results show that thickness fluctuation scattering is the main limitation. • Two-dimensional electron gas (2DEG) mobility is a function of 2DEG density. • TF scattering is the main limitation when 2DEG density exceeds 2 × 10 12 cm −2

A comparison of LIDT behavior of metal-dielectric mirrors in ns and ps pulse regime at 1030 nm with regard to the coating technology

Science.gov (United States)

Škoda, Václav; Vanda, Jan; Uxa, Štěpán

2017-11-01

Several sets of mirror samples with multilayer system Ta2O5/SiO2 on silver metal layer were manufactured using either PVD or IAD coating technology. Both BK7 and fused silica substrates were used for preparation of samples. Laserinduced- damage-threshold (LIDT) of metal-dielectric mirrors was tested using a laser apparatus working at 1030 nm wavelength, in ns and ps pulse length domains in S-on-1 test mode. The measured damage threshold values at 45 deg angle of incidence and P-polarization were compared for different pulse length, substrate materials and coating technology.

Reduction of microbial contamination and improvement of germination of sweet basil (Ocimum basilicum L.) seeds via surface dielectric barrier discharge

Czech Academy of Sciences Publication Activity Database

Ambrico, P. F.; Šimek, Milan; Morano, M.; De Miccolis Angelini, R.M.; Minafra, A.; Trotti, P.; Ambrico, M.; Prukner, Václav; Faretra, F.

2017-01-01

Roč. 50, č. 30 (2017), č. článku 305401. ISSN 0022-3727 R&D Projects: GA ČR(CZ) GA15-04023S Institutional support: RVO:61389021 Keywords : dielectric barrier discharges (DBD) * bio-decontamination * etching * polymers * biomolecules * spores * surface treatment Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 2.588, year: 2016 https://doi.org/10.1088/1361-6463/aa77c8

Degradation of benzodiazepines using water falling film dielectric barrier discharge reactor

Directory of Open Access Journals (Sweden)

Radulović Vesna M.

2017-01-01

Full Text Available Classical methods of wastewater treatment are often not suitable for the treatment of pharmaceutical waste. The previous studies have shown that the use of the advanced oxidation procedures (AOP can lead to a more efficient degradation of various biologically active compounds, which are active pharmaceutical ingredients of applied drugs. The aim of this paper is the application of the plasma technology on the degradation of a two active pharmaceutical ingredients (APIs, diazepam and alprazolam and the finished products (Bensedin® and Ksalol® using the dielectric barrier discharge (DBD reactor for AOP. We studied the degradation rate of these pharmaceuticals, depending on the number of passes through the reactor. This degradation method was efficient 61 % for diazepam and 95 % alprazolam. We also examined the influence of the pH adjustment between the passes of APIs through the DBD reactor. The degradation rate of APIs and the finished products was monitored by the high performance liquid chromatography (HPLC technique, using a photodiode array detector. The concentration of the dissolved ozone was determined using the iodometric procedure. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 172030

Effect of Cooling Methods on Methane Conversion via Dielectric-Barrier Discharges

International Nuclear Information System (INIS)

Wang Baowei; Yang Kuanhui; Xu Genhui

2008-01-01

Effects of cooling methods on stability and methane conversion rate using dielectric-barrier discharges (DBD) were systematically investigated in this article. The results showed that the methane conversion rate was as high as 44.43% in a pure methane system at a flow rate of 100 mL ± min -1 and an input power of 234.2 W with air cooling. A dark greenish and soft film-like carbon was deposited on the outer surface of quartz tube when the outer electrode was water-cooled, which decreased the methane conversion. With air cooling of inner electrode the selectivity of C 2 hydrocarbons was higher than that with other cooling methods, while the C 3 hydrocarbons had higher selectivity with flowing water cooling. Cooling the inner electrode could restrain the carbon deposition, but would decrease the methane conversion rate. The stability of both reaction and plasma operation can be improved through cooling the reactor. From thermodynamic analysis, it was found that the effective collisions frequency among the reactant molecules and free electrons (e - ) increased with temperature, which in turn led to a higher methane conversion rate and a change in the distribution of products.

Degradation of m-cresol in aqueous solution by dielectric barrier discharge

International Nuclear Information System (INIS)

Jaramillo-Sierra, B; De la Piedad-Benitez, A; Mercado-Cabrera, A; López-Callejas, R; Peña-Eguiluz, R; Barocio, S R; Valencia-Alvarado, R; Rodríguez-Méndez, B; Muñoz-Castro, A

2012-01-01

It was carried out a theoretical and experimental study of the m-cresol degradation in aqueous solution using a non-thermal plasma induced by dielectric barrier discharge. For the experimental setup a coaxial reactor vertically placed was used. Wherein a liquid solution flowing inside the internal electrode was impelled by a peristaltic pump and falling over the external surface of the internal electrode. Working gas was applied in a parallel direction respect to the surface of the liquid and inside of the quartz tube. Non-thermal plasma was generated at the gas-liquid interface in Ar-O 2 gas mixtures with a high-voltage power supply system. The electric power applied ranged from 10–60W at a 3.0 kHz frequency. The initial concentration of m-cresol was of 5 × 10 −3 mol/L, and the removal efficiency up to 97.3% was obtained after 1 h of treatment. For the theoretical study a simplified model of the chemical kinetics was developed where the temporary evolution of the compounds generated in the process of degradation of the m-cresol was analyzed. Byproducts as oxalic acid and CO 2 were found.

Manipulation of stored charge in anodic aluminium oxide/SiO{sub 2} dielectric stacks by the use of pulsed anodisation

Energy Technology Data Exchange (ETDEWEB)

Lu, Zhong, E-mail: z.lu@unsw.edu.au [School of Photovoltaic and Renewable Energy Engineering, The University of New South Wales, Sydney, NSW 2052 (Australia); Ouyang, Zi [School of Photovoltaic and Renewable Energy Engineering, The University of New South Wales, Sydney, NSW 2052 (Australia); Grant, Nicholas; Wan, Yimao; Yan, Di [Centre for Sustainable Energy Systems, Faculty of Engineering and Information Technology, The Australian National University, Canberra, ACT 0200 (Australia); Lennon, Alison [School of Photovoltaic and Renewable Energy Engineering, The University of New South Wales, Sydney, NSW 2052 (Australia)

2016-02-15

Graphical abstract: - Highlights: • Pulse anodisation was used to grow AAO layers with controllable stored charge. • Stored charge density ranging from −5.2 × 10{sup 11} to 2.5 × 10{sup 12} q/cm{sup 2} was demonstrated. • Enhancement in surface passivation was demonstrated with charge management. • Annealing significantly reduces the positive stored charge and the interface defect. - Abstract: A method of fabricating anodic aluminium oxide (AAO) with the capability of manipulating its stored charge is reported. This method involves the use of a pulsed current source to anodise aluminium layers instead of the typically used constant current/voltage source, with the test structures experiencing positive and negative cycles periodically. By tuning the positive cycle percentage, it is demonstrated that the effective stored charge density can be manipulated in a range from −5.2 × 10{sup 11} to 2.5 × 10{sup 12} q/cm{sup 2} when the AAO is formed over a 12 nm SiO{sub 2} layer. An investigation of the stored charge distribution in the dielectric stacks indicates a positive fixed charge at the SiO{sub 2}/Si interface, a negative fixed charge at the AAO/SiO{sub 2} interface and a positive bulk charge within the AAO layer. The effective stored charge density and interface states were found to be affected by annealing conditions and it is suggested that oxygen annealing can reduce the bulk positive charge while post-metallisation anneal is most effective in reducing silicon interface defects. Charge manipulation using pulsed anodisation is shown to reduce carrier recombination on boron-diffused silicon surfaces highlighting the potential of the process to be used to tune the electrical properties of dielectric layers so that they can reduce surface recombination on silicon surfaces having different dopant polarity and concentrations.

Femtosecond laser excitation of dielectric materials

DEFF Research Database (Denmark)

Wædegaard, Kristian Juncher; Balling, Peter; Frislev, Martin Thomas

2012-01-01

We report an approach to modeling the interaction between ultrashort laser pulses and dielectric materials. The model includes the excitation of carriers by the laser through strongfield excitation, collisional excitation, and absorption in the plasma consisting of conduction-band electrons formed...

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

Energy Technology Data Exchange (ETDEWEB)

Liu, Weibo; Dong, Lifang, E-mail: donglfhbu@163.com, E-mail: pyy1616@163.com; Wang, Yongjie; Zhang, Xinpu [College of Physics Science and Technology, Hebei University, Baoding 071002 (China); College of Quality and Technical Supervision, Hebei University, Baoding 071002 (China); Pan, Yuyang, E-mail: donglfhbu@163.com, E-mail: pyy1616@163.com [College of Quality and Technical Supervision, Hebei University, Baoding 071002 (China)

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.

Influence of dielectric barrier discharge treatment on mechanical and dyeing properties of wool

Science.gov (United States)

Rahul, NAVIK; Sameera, SHAFI; Md Miskatul, ALAM; Md Amjad, FAROOQ; Lina, LIN; Yingjie, CAI

2018-06-01

Physical and chemical properties of wool surface significantly affect the absorbency, rate of dye bath exhaustion and fixation of the industrial dyes. Hence, surface modification is a necessary operation prior to coloration process in wool wet processing industries. Plasma treatment is an effective alternative for physiochemical modification of wool surface. However, optimum processing parameters to get the expected modification are still under investigation, hence this technology is still under development in the wool wet processing industries. Therefore, in this paper, treatment parameters with the help of simple dielectric barrier discharge plasma reactor and air as a plasma gas, which could be a promising combination for treatment of wool substrate at industrial scale were schematically studied, and their influence on the water absorbency, mechanical, and dyeing properties of twill woven wool fabric samples are reported. It is expected that the results will assist to the wool coloration industries to improve the dyeing processes.

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

International Nuclear Information System (INIS)

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

2008-01-01

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

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

Science.gov (United States)

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

2008-02-01

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

Removal of main exhaust gases of vehicles by a double dielectric barrier discharge

International Nuclear Information System (INIS)

Pacheco, M; Valdivia, R; Pacheco, J; Rivera, C; Alva, E; Santana, A; Huertas, J; Lefort, B; Estrada, N

2012-01-01

Because the health effects and their contribution to climate change, the emissions of toxic gases are becoming more controlled. In order to improve the diminution of toxic gases to the atmosphere, several techniques have been developed; here it will be focus only to automotive emissions. This work deals about the treatment of toxic gases emitted from vehicles by a non-thermal plasma. Several tests were done in a 4-cylinder 2002/Z16SE motor to characterize the vehicle emissions. With these results gas mixture simulating the exhaust gases vehicles, was used in experiments at different conditions employing a double dielectric barrier reactor for their treatment. The removal efficiencies superior to 90% show the competence of the non-thermal plasma reactor to treat these gases. Experimental results are explained with the aid of a simple chemical model that suggests a possible mechanism of degradation of toxic gases. The plasma reactor employed could works at 12V supplied without difficulty by a vehicle battery.

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

Science.gov (United States)

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.

Theory of the forces exerted by Laguerre-Gaussian light beams on dielectrics

International Nuclear Information System (INIS)

Loudon, Rodney

2003-01-01

The classical theory of the electromagnetic field associated with paraxial Laguerre-Gaussian light is generalized to apply to propagation in a bulk dielectric, and the theory is quantized to obtain expressions for the electric and magnetic field operators. The forms of the Poynting vector and angular momentum density operators are derived and their expectation values for a single-photon wave packet are obtained. The Lorentz force operator in the dielectric is resolved into longitudinal, radial, and azimuthal components. The theory is extended to apply to an interface between two semi-infinite dielectric media, one of which is transparent with an incident single-photon pulse, and the other of which is weakly attenuating. For a pulse that is much shorter than the attenuation length, the theory can separately identify the surface and bulk contributions to the Lorentz force on the attenuating dielectric. Particular attention is given to the transfer of longitudinal and angular momentum to the dielectric from light incident from free space. The resulting expressions for the shift and rotation of a transparent dielectric slab are shown to agree with those obtained from Einstein box theories

Pulsed Magnetic Field Improves the Transport of Iron Oxide Nanoparticles through Cell Barriers

Science.gov (United States)

Min, Kyoung Ah; Shin, Meong Cheol; Yu, Faquan; Yang, Meizhu; David, Allan E.; Yang, Victor C.; Rosania, Gus R.

2013-01-01

Understanding how a magnetic field affects the interaction of magnetic nanoparticles (MNPs) with cells is fundamental to any potential downstream applications of MNPs as gene and drug delivery vehicles. Here, we present a quantitative analysis of how a pulsed magnetic field influences the manner in which MNPs interact with, and penetrate across a cell monolayer. Relative to a constant magnetic field, the rate of MNP uptake and transport across cell monolayers was enhanced by a pulsed magnetic field. MNP transport across cells was significantly inhibited at low temperature under both constant and pulsed magnetic field conditions, consistent with an active mechanism (i.e. endocytosis) mediating MNP transport. Microscopic observations and biochemical analysis indicated that, in a constant magnetic field, transport of MNPs across the cells was inhibited due to the formation of large (>2 μm) magnetically-induced MNP aggregates, which exceeded the size of endocytic vesicles. Thus, a pulsed magnetic field enhances the cellular uptake and transport of MNPs across cell barriers relative to a constant magnetic field by promoting accumulation while minimizing magnetically-induced MNP aggregates at the cell surface. PMID:23373613

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

Directory of Open Access Journals (Sweden)

Istadi Istadi

2014-07-01

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

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

Science.gov (United States)

2013-07-01

around 2 ms and 12 ms in this figure, and during the discharge period, the current was continuous without any pulse . Once a discharge generated in...electron avalanches [10]. Fig. 1. High pressure ozone generator. (a) Top view (b) Side view Fig. 2. Barrier discharge device. Table 1... discharge N. Osawa P1 P, UY. Yoshioka UP2 P, R. Hanaoka P1 P 1 Center for Electric, Optic and Energy applications, Department of Electric and

Effects of N2O and O2 addition to nitrogen Townsend dielectric barrier discharges at atmospheric pressure on the absolute ground-state atomic nitrogen density

KAUST Repository

Es-sebbar, Et-touhami; Gherardi, Nicolas; Massines, Franç oise

2012-01-01

Absolute ground-state density of nitrogen atoms N (2p3 4S3/2) in non-equilibrium Townsend dielectric barrier discharges (TDBDs) at atmospheric pressure sustained in N2/N2O and N2/O2 gas mixtures has been measured using Two-photon absorption laser

Characterization of pulsed atmospheric-pressure plasma streams (PAPS) generated by a plasma gun

Science.gov (United States)

Robert, E.; Sarron, V.; Riès, D.; Dozias, S.; Vandamme, M.; Pouvesle, J.-M.

2012-06-01

An experimental study of atmospheric-pressure rare gas plasma propagation in a high-aspect-ratio capillary is reported. The plasma is generated with a plasma gun device based on a dielectric barrier discharge (DBD) reactor powered by either nanosecond or microsecond rise-time high-voltage pulses at single-shot to multi-kHz frequencies. The influence of the voltage waveform, pulse polarity, pulse repetition rate and capillary material have been studied using nanosecond intensified charge-coupled device imaging and plasma-front velocity measurements. The evolution of the plasma appearance during its propagation and the study of the role of the different experimental parameters lead us to suggest a new denomination of pulsed atmospheric-pressure plasma streams to describe all the plasma features, including the previously so-called plasma bullet. The unique properties of such non-thermal plasma launching in capillaries, far from the primary DBD plasma, are associated with a fast ionization wave travelling with velocity in the 107-108 cm s-1 range. Voltage pulse tailoring is shown to allow for a significant improvement of such plasma delivery. Thus, the plasma gun device affords unique opportunities in biomedical endoscopic applications.

Characterization of pulsed atmospheric-pressure plasma streams (PAPS) generated by a plasma gun

International Nuclear Information System (INIS)

Robert, E; Sarron, V; Riès, D; Dozias, S; Vandamme, M; Pouvesle, J-M

2012-01-01

An experimental study of atmospheric-pressure rare gas plasma propagation in a high-aspect-ratio capillary is reported. The plasma is generated with a plasma gun device based on a dielectric barrier discharge (DBD) reactor powered by either nanosecond or microsecond rise-time high-voltage pulses at single-shot to multi-kHz frequencies. The influence of the voltage waveform, pulse polarity, pulse repetition rate and capillary material have been studied using nanosecond intensified charge-coupled device imaging and plasma-front velocity measurements. The evolution of the plasma appearance during its propagation and the study of the role of the different experimental parameters lead us to suggest a new denomination of pulsed atmospheric-pressure plasma streams to describe all the plasma features, including the previously so-called plasma bullet. The unique properties of such non-thermal plasma launching in capillaries, far from the primary DBD plasma, are associated with a fast ionization wave travelling with velocity in the 10 7 –10 8 cm s −1 range. Voltage pulse tailoring is shown to allow for a significant improvement of such plasma delivery. Thus, the plasma gun device affords unique opportunities in biomedical endoscopic applications. (paper)

Study on the characteristics of barrier free surface discharge driven by repetitive nanosecond pulses at atmospheric pressure

Energy Technology Data Exchange (ETDEWEB)

Lei, Pang; Qiaogen, Zhang [State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Xi' an 710049 (China); Kun, He [China Electric Power Research Institute, Beijing 100192 (China); Chunliang, Liu [State Key Laboratory for Physical Electronics and Devices, Xi' an Jiaotong University, Xi' an 710049 (China)

2016-05-15

Nanosecond pulsed plasma has an enormous potential in many applications. In this paper, the characteristics of barrier free nanosecond pulsed surface discharge are investigated by the use of an actuator with a strip-strip film electrode configuration, including the effect of electrode width and the gap distance on the plasma morphology and electrical characteristics at atmospheric pressure. It was found that it is relative easier to generate a quasi uniform discharge with a thinner electrode width and a smaller gap distance. The underlying physical mechanism was also discussed. Besides that, the influence of airflow on repetitive pulsed surface discharge was examined. By comparing to the discharge produced by two different pulse waveforms in airflows, we found that the discharge driven by a faster pulse behaves more stable. Finally, a model was developed to analyze the interaction of the airflow and the discharge channels.

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

International Nuclear Information System (INIS)

Hu Miao; Guo Yun

2012-01-01

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. (plasma technology)

Pulsed power

International Nuclear Information System (INIS)

Anon.

1977-01-01

The key element of our pulsed power program is concentration of power in time and space by suppression of breakdown in dielectrics and in vacuum. Magnetically insulated vacuum transmission lines and magnetic suppression of insulator flashover have continued as the main reserch directions. Vacuum insulated line studies at Physics International have been expanded and a test bed at Sandia, called MITE (Magnetically Insulated Transmission Experiment), is under development. The choice for the baseline EBFA design will depend on the outcome of these studies and should be made in July 1977. The slow and intermediate speed pulsed power approaches to EBFA will be based on Proto I and Proto II results and several of the projected EBFA subsystems are presently being tested in Proto II. A further stage of power concentration, within the vacuum diode itself, would considerably ease the burden on dielectrics; methods of power multiplication involving magnetically imploded plasmas are being considered and tests have begun using the Ripple III apparatus

Treatment of Wastewater with High Conductivity by Pulsed Discharge Plasma

Science.gov (United States)

Wang, Zhaojun; Jiang, Song; Liu, Kefu

2014-07-01

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

Treatment of Wastewater with High Conductivity by Pulsed Discharge Plasma

International Nuclear Information System (INIS)

Wang Zhaojun; Jiang Song; Liu Kefu

2014-01-01

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

Study of HV Dielectrics for High Frequency Operation in Linear & Nonlinear Transmission Lines & Simulation & Development of Hybrid Nonlinear Lines for RF Generation

Science.gov (United States)

2015-08-27

As shown in [4], [5], the capacitors based on PZT (lead-zirconate- titanate) and BT dielectrics have dielectric BD strength of the order of 50 kV/cm...results. Depending on the nonlinearity properties of the capacitor dielectric , input pulse rise time, output pulse sharpening and or RF soliton... capacitors in a frequency range up to 2 MHz, below the resonant frequency of the both dielectrics . As seen in Fig. 1, PZTs have better performance than

Direct electron-impact mechanism of excitation of mercury monobromide in a double-pulse dielectric-barrier-discharge HgBr lamp

Science.gov (United States)

Datsyuk, V. V.; Izmailov, I. A.; Naumov, V. V.; Kochelap, V. A.

2016-08-01

In a nonequlibrium plasma of a gas-discharge HgBr lamp, the terminal electronic state of the HgBr(B-X) radiative transition with a peak wavelength of 502 nm remains populated for a relatively long time and is repeatedly excited to the B state in collisions with plasma electrons. This transfer of the HgBr molecules from the ground state X to the excited state B is the main mechanism of formation of the light-emitting molecules especially when the lamp is excited by double current pulses. According to our simulations, due to the electron-induced transitions between HgBr(X) and HgBr(B), the output characteristics of the DBD lamp operating in a double-pulse regime are better than those of the lamp operating in a single-pulse regime. In the considered case, the peak power is calculated to increase by a factor of about 2 and the lamp efficiency increases by about 50%.

Flow control over a NACA 0012 airfoil using dielectric-barrier-discharge plasma actuator with a Gurney flap

Energy Technology Data Exchange (ETDEWEB)

Feng, Li-Hao [Beijing University of Aeronautics and Astronautics, Fluid Mechanics Key Laboratory of Education Ministry, Beijing (China); University of Nottingham, University Park, Faculty of Engineering, Nottingham (United Kingdom); Jukes, Timothy N. [University of Nottingham, University Park, Faculty of Engineering, Nottingham (United Kingdom); AIST, Research Centre for New Fuels and Vehicle Technology, Tsukuba (Japan); Choi, Kwing-So [University of Nottingham, University Park, Faculty of Engineering, Nottingham (United Kingdom); Wang, Jin-Jun [Beijing University of Aeronautics and Astronautics, Fluid Mechanics Key Laboratory of Education Ministry, Beijing (China)

2012-06-15

Flow control study of a NACA 0012 airfoil with a Gurney flap was carried out in a wind tunnel, where it was demonstrated that a dielectric-barrier-discharge (DBD) plasma actuator attached to the flap could increase the lift further, but with a small drag penalty. Time-resolved PIV measurements of the near-wake region indicated that the plasma forcing shifted the wake downwards, reducing its recirculation length. Analysis of wake vortex dynamics suggested that the plasma actuator initially amplified the lower wake shear layer by adding momentum along the downstream surface of the Gurney flap. This enhanced mutual entrainment between the upper and lower wake vortices, leading to an increase in lift on the airfoil. (orig.)

Fluorescence measurement of atomic oxygen concentration in a dielectric barrier discharge

Science.gov (United States)

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.

Effects of hydrocarbon contamination on ozone generation with dielectric barrier discharges

Science.gov (United States)

Lopez, Jose L.; Vezzu, Guido; Freilich, Alfred; Paolini, Bernhard

2013-08-01

The increasing usage of the feed gases of lower grade liquid oxygen (LOX) containing higher levels of trace hydrocarbon impurities in dielectric barrier discharge (DBD) for ozone generation requires a better understanding of the kinetics of the by-product formation resulting from reactions involving these hydrocarbon impurities. As a case study of hydrocarbon impurities, the kinetics of CH4 conversion in DBDs and the subsequent HNO3 formation were investigated by means of gas-phase plasma diagnostics, supported by detailed process modeling, and extensive in-situ and ex-situ by-product analysis. The by-products formation in the plasma with the presence of CH4, were found to differ significantly in oxygen-fed generators as compared to generators fed with oxygen/nitrogen mixtures. The amount of HNO3 formed depends on the concentration of NOx formed in the plasma and the amount of CH4 that is converted, but not on the O3 concentration. In the present work we have investigated CH4 concentrations of up to 1.95 wt% of the feed gas. The rate of deterioration of the overall ozone generator performance was found to be affected by the concentration of nitrogen in the oxygen/nitrogen mixture.

Dielectric properties of nanosilica filled epoxy nanocomposites

Indian Academy of Sciences (India)

M G Veena

Polymer nanocomposites are the 21st century engineering materials with wide range of ... the electronic industry for dielectric materials in electrical insulation ..... be ascribed to the interface barriers and chain entangle- ments towards the ...

Comparison of different applied voltage waveforms on CO{sub 2} reforming of CH{sub 4} in an atmospheric plasma system

Energy Technology Data Exchange (ETDEWEB)

Nguyen, Duc Ba; Lee, Won Gyu [Kangwon National University, Chuncheon (Korea, Republic of)

2015-01-15

Sinusoidal and pulse waveforms of applied voltage were employed for CO{sub 2} reforming of CH{sub 4} to syngas in an atmospheric dielectric barrier discharge reactor. The discharge power of a pulse waveform was higher than that of sinusoidal waveform at the same applied voltage. The plasma reaction by a pulse waveform enhanced the conversion of CO{sub 2} and CH{sub 4} and the selectivity of H{sub 2} and CO. It was confirmed that CO{sub 2} reforming of CH{sub 4} can be improved by the adaption of pulse-type power supply in a dielectric barrier discharge reactor immersed in an electrically insulating oil bath.

Fischer-Tropsch Performance of an SiO2-Supported Co-Based Catalyst Prepared by Hydrogen Dielectric-Barrier Discharge Plasma

International Nuclear Information System (INIS)

Fu Tingjun; Huang Chengdu; Lv Jing; Li Zhenhua

2014-01-01

A silica-supported cobalt catalyst was prepared by hydrogen dielectric-barrier discharge (H 2 -DBD) plasma. Compared to thermal hydrogen reduction, H 2 -DBD plasma treatment can not only fully decompose the cobalt precursor but also partially reduce the cobalt oxides at lower temperature and with less time. The effect of the discharge atmosphere on the property of the plasma-prepared catalyst and the Fischer-Tropsch synthesis activity was studied. The results indicate that H 2 -DBD plasma treatment is a promising alternative for preparing Co/SiO 2 catalysts from the viewpoint of energy savings and efficiency

Surface modification of PET films using dielectric barrier discharge driven by repetitive nanosecond-pulses

International Nuclear Information System (INIS)

Shao Tao; Zhang Cheng; Long Kaihua; Wang Jue; Zhang Dongdong; Yan Ping; Zhou Yuanxiang

2010-01-01

In this paper, surface treatment of PET films for improving the hydrophilicity using DBD excited by unipolar nanosecond-pulses is presented. Homogeneous and filamentary discharge are obtained under certain experimental conditions and then used to modify the surface of PET films. The properties of PET films before and after treatment are characterized with water contact angle measurement, atomic force microscope and X-ray photoelectron spectroscope. The experimental results show that static water contact angles decrease after DBD plasma treatment and the observed contact angle is changed from 80 degree for the untreated samples to 20 degree after treatment. However, the decrease of contact angles is not continuous and it will reach a saturation state after certain treatment time. The improvement of surface hydrophilicity can be attributed to the enhancement of the surface roughness and introduction of oxygen-containing polar functional groups. In contrast with the filamentary DBD treatment, the homogenous DBD is more effective in PET surface treatment. (authors)

Investigation of plate-type barrier ozonizers with AC and pulse power supplies

International Nuclear Information System (INIS)

Krasnij, V.V.; Gubarev, S.P.; Pogoghev, D.P.; Sokolova, O.T.

2002-01-01

In this paper the experimental results on the investigation of plate-type reactors operated on the base of barrier discharge have been presented. Different reactors with planar, strip, and trench electrodes were investigated. Such reactors operated under atmospheric pressure with ac and pulse power sources with voltage of up to 10 kV, frequency up to 12 kHz. Using atomized spectroscopy system the measurements of the main specifications of the reactors such as ozone yielding rate, the temperature in the reactor and the air flow rate were carried out

Surface Treatment of Polypropylene Films Using Dielectric Barrier Discharge with Magnetic Field

International Nuclear Information System (INIS)

Wang Changquan; Zhang Guixin; Wang Xinxin; Chen Zhiyu

2012-01-01

Atmospheric pressure non-thermal plasma is of interest for industrial applications. In this study, polypropylene (PP) films are modified by a dielectric barrier discharge (DBD) with a non-uniform magnetic field in air at atmospheric pressure. The surface properties of the PP films before and after a DBD treatment are studied by using contact angle measurement, atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The effect of treatment time on the surface modification with and without a magnetic field is investigated. It is found that the hydrophilic improvement depends on the treatment time and magnetic field. It is also found that surface roughness and oxygen-containing groups are introduced onto the PP film surface after the DBD treatment. Surface roughness and oxygen-containing polar functional groups of the PP films increase with the magnetic induction density. The functional groups are identified as C-O, C=O and O-C=O by using XPS analysis. It is concluded that the hydrophilic improvement of PP films treated with a magnetic field is due to a greater surface roughness and more oxygen-containing groups. (plasma technology)

Accelerating Dielectrics Design Using Thinking Machines

Science.gov (United States)

Ramprasad, R.

2013-03-01

High energy density capacitors are required for several pulsed power and energy storage applications, including food preservation, nuclear test simulations, electric propulsion of ships and hybrid electric vehicles. The maximum electrostatic energy that can be stored in a capacitor dielectric is proportional to its dielectric constant and the square of its breakdown field. The current standard material for capacitive energy storage is polypropylene which has a large breakdown field but low dielectric constant. We are involved in a search for new classes of polymers superior to polypropylene using first principles computations combined with statistical and machine learning methods. Essential to this search are schemes to efficiently compute the dielectric constant of polymers and the intrinsic dielectric breakdown field, as well as methods to determine the stable structures of new classes of polymers and strategies to efficiently navigate through the polymer chemical space offered by the periodic table. These methodologies have been combined with statistical learning paradigms in order to make property predictions rapidly, and promising classes of polymeric systems for energy storage applications have been identified. This work is being supported by the Office of Naval Research.

Field-emitting Townsend regime of surface dielectric barrier discharges emerging at high pressure up to supercritical conditions

International Nuclear Information System (INIS)

Pai, David Z; Stauss, Sven; Terashima, Kazuo

2015-01-01

Surface dielectric barrier discharges (DBDs) in CO 2 from atmospheric pressure up to supercritical conditions generated using 10 kHz ac excitation are investigated experimentally. Using current–voltage and charge–voltage measurements, imaging, optical emission spectroscopy, and spontaneous Raman spectroscopy, we identify and characterize a field-emitting Townsend discharge regime that emerges above 0.7 MPa. An electrical model enables the calculation of the discharge-induced capacitances of the plasma and the dielectric, as well as the space-averaged values of the surface potential and the potential drop across the discharge. The space-averaged Laplacian field is accounted for in the circuit model by including the capacitance due to the fringe electric field from the electrode edge. The electrical characteristics are demonstrated to fit the description of atmospheric-pressure Townsend DBDs (Naudé et al 2005 J. Phys. D: Appl. Phys. 38 530–8), i.e. self-sustained DBDs with minimal space-charge effects. The purely continuum emission spectrum is due to electron–neutral bremsstrahlung corresponding to an average electron temperature of 2600 K. Raman spectra of CO 2 near the critical point demonstrate that the average gas temperature increases by less than 1 K. (paper)

Quantum-optical input-output relations for dispersive and lossy multilayer dielectric plates

International Nuclear Information System (INIS)

Gruner, T.; Welsch, D.

1996-01-01

Using the Green-function approach to the problem of quantization of the phenomenological Maxwell theory, the propagation of quantized radiation through dispersive and absorptive multilayer dielectric plates is studied. Input-output relations are derived, with special emphasis on the determination of the quantum noise generators associated with the absorption of radiation inside the dielectric matter. The input-output relations are used to express arbitrary correlation functions of the outgoing field in terms of correlation functions of the incoming field and those of the noise generators. To illustrate the theory, photons at dielectric tunneling barriers are considered. It is shown that inclusion in the calculations of losses in the photonic band gaps may substantially change the barrier traversal times. copyright 1996 The American Physical Society

Photocatalytic Degradation Effect of μ-Dielectric Barrier Discharge Plasma Treated Titanium Dioxide Nanoparticles on Environmental Contaminant.

Science.gov (United States)

Seo, Hyeon Jin; Hwang, Ki-Hwan; Na, Young Hoon; Boo, Jin-Hyo

2018-09-01

This study focused on the photocatalytic degradation effect of the μ-dielectric barrier discharge (μ-DBD) plasma treated titanium dioxide (TiO2) nanoparticles on environmental contaminant such as formaldehyde. TiO2 nanoparticles were treated by a μ-DBD plasma source with nitrogen gas. We analyzed the degradation of formaldehyde with the plasma treated TiO2 nanoparticles by UV-visible spectrophotometer (UV-VIS), and demonstrated that the photocatalytic activity of the μ-DBD plasma-treated TiO2 nanoparticles showed significantly high catalytic efficiency rather than without plasma treated TiO2 nanoparticles. Field emission scanning electron microscopes (FE-SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and water contact angle analyzer were used to measure the effects of photocatalytic degradation for the plasma treated TiO2 nanoparticles.

Silver Nanowire/MnO2 Nanowire Hybrid Polymer Nanocomposites: Materials with High Dielectric Permittivity and Low Dielectric Loss.

Science.gov (United States)

Zeraati, Ali Shayesteh; Arjmand, Mohammad; Sundararaj, Uttandaraman

2017-04-26

This study reports the fabrication of hybrid nanocomposites based on silver nanowire/manganese dioxide nanowire/poly(methyl methacrylate) (AgNW/MnO 2 NW/PMMA), using a solution casting technique, with outstanding dielectric permittivity and low dielectric loss. AgNW was synthesized using the hard-template technique, and MnO 2 NW was synthesized employing a hydrothermal method. The prepared AgNW:MnO 2 NW (2.0:1.0 vol %) hybrid nanocomposite showed a high dielectric permittivity (64 at 8.2 GHz) and low dielectric loss (0.31 at 8.2 GHz), which are among the best reported values in the literature in the X-band frequency range (8.2-12.4 GHz). The superior dielectric properties of the hybrid nanocomposites were attributed to (i) dimensionality match between the nanofillers, which increased their synergy, (ii) better dispersion state of AgNW in the presence of MnO 2 NW, (iii) positioning of ferroelectric MnO 2 NW in between AgNWs, which increased the dielectric permittivity of nanodielectrics, thereby increasing dielectric permittivity of the hybrid nanocomposites, (iv) barrier role of MnO 2 NW, i.e., cutting off the contact spots of AgNWs and leading to lower dielectric loss, and (v) AgNW aligned structure, which increased the effective surface area of AgNWs, as nanoelectrodes. Comparison of the dielectric properties of the developed hybrid nanocomposites with the literature highlights their great potential for flexible capacitors.

Attosecond control of electron beams at dielectric and absorbing membranes

Science.gov (United States)

Morimoto, Yuya; Baum, Peter

2018-03-01

Ultrashort electron pulses are crucial for time-resolved electron diffraction and microscopy of the fundamental light-matter interaction. In this work, we study experimentally and theoretically the generation and characterization of attosecond electron pulses by optical-field-driven compression and streaking at dielectric or absorbing interaction elements. The achievable acceleration and deflection gradient depends on the laser-electron angle, the laser's electric and magnetic field directions, and the foil orientation. Electric and magnetic fields have similar contributions to the final effect and both need to be considered. Experiments and theory agree well and reveal the optimum conditions for highly efficient, velocity-matched electron-field interactions in the longitudinal or transverse direction. We find that metallic membranes are optimum for light-electron control at mid-infrared or terahertz wavelengths, but dielectric membranes are excellent in the visible and near-infrared regimes and are therefore ideal for the formation of attosecond electron pulses.

Time-resolved processes in a pulsed electrical discharge in argon bubbles in water

Science.gov (United States)

Gershman, S.; Belkind, A.

2010-12-01

A phenomenological picture of a pulsed electrical discharge in gas bubbles in water is produced by combining electrical, spectroscopic, and imaging characterization methods. The discharge is generated by applying 1 μ s pulses of 5 to 20 kV between a needle and a disk electrode submerged in water. An Ar gas bubble surrounds the tip of the needle electrode. Imaging, electrical characteristics, and time-resolved optical emission spectroscopic data suggest a fast streamer propagation mechanism and the formation of a plasma channel in the bubble. Comparing the electrical and imaging data for consecutive pulses applied to the bubble at a frequency of 1 Hz indicates that each discharge proceeds as an entirely new process with no memory of the previous discharge aside from the presence of long-lived chemical species, such as ozone and oxygen. Imaging and electrical data show the presence of two discharge events during each applied voltage pulse, a forward discharge near the beginning of the applied pulse depositing charge on the surface of the bubble and a reverse discharge removing the accumulated charge from the water/gas interface when the applied voltage is turned off. The pd value of ~ 300-500 torr cm, the 1 μs long pulse duration, low repetition rate, and unidirectional character of the applied voltage pulses make the discharge process here unique compared to the traditional corona or dielectric barrier discharges.

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

Science.gov (United States)

Machrafi, H.; Cavadias, S.; Amouroux, J.

2011-03-01

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

Experimental and computational study of dielectric barrier discharges for environmental applications

Science.gov (United States)

Aerts, Robby

Air pollution has become a major global concern which affects all inhabitants of our precious earth. Nowadays it is fact that our climate is changing and the sea level is rising. Moreover, we are facing an energy crisis because all our fossil fuel resources will sooner or later be running empty. It is clear that drastic measures are needed to keep our planet as it is today for generations to come. One of these measures is the 20-20-20 targets imposed by the European Commission, which stimulates the research for environmental energy applications. In this PhD dissertation two environmental applications of plasma technology are investigated. The first one is the abatement of flue gases, and more specifically the destruction of volatile organic compounds (VOCs). The second one is the conversion of CO2 into valuable chemicals. Both of these applications suffer from a large energy cost under classical (thermodynamic) conditions, due to the chemical stability of these molecules. Plasma technology is quite promising to overcome these thermodynamic barriers. Plasmas allow reactions at different time-scales with different species, such as electrons, ions, radicals, molecules and excited species, creating new chemical pathways. Indeed, in a plasma the applied electrical energy is directly transferred to the electrons, which activate the gas by ionization, excitation and dissociation, hence creating reactive species (ions, excited species, radicals), that can further easily undergo other chemical reactions. Especially gas discharges, which are low temperature plasmas, show promising results in the destruction of pollutants at mild conditions. A common type of gas discharge is the dielectric barrier discharge (DBD) which has been successfully scaled up for industrial ozone generation and is widely investigated in the field of environmental applications. The complexity of DBDs creates difficulties for experimental diagnostics and therefore numerical studies can help to improve

Hysteresis in Lanthanide Aluminum Oxides Observed by Fast Pulse CV Measurement

Directory of Open Access Journals (Sweden)

Chun Zhao

2014-10-01

Full Text Available Oxide materials with large dielectric constants (so-called high-k dielectrics have attracted much attention due to their potential use as gate dielectrics in Metal Oxide Semiconductor Field Effect Transistors (MOSFETs. A novel characterization (pulse capacitance-voltage method was proposed in detail. The pulse capacitance-voltage technique was employed to characterize oxide traps of high-k dielectrics based on the Metal Oxide Semiconductor (MOS capacitor structure. The variation of flat-band voltages of the MOS structure was observed and discussed accordingly. Some interesting trapping/detrapping results related to the lanthanide aluminum oxide traps were identified for possible application in Flash memory technology. After understanding the trapping/detrapping mechanism of the high-k oxides, a solid foundation was prepared for further exploration into charge-trapping non-volatile memory in the future.

Electrophysical properties of microalloyed alumo-silicate ceramics as active dielectric

Directory of Open Access Journals (Sweden)

Purenović Jelena

2013-01-01

Full Text Available In this paper, electrophysical properties of porous alumo-silicate ceramics, modified by alloying with magnesium and microalloying with aluminum, were investigated. Complex multiphase system, as active microalloyed ceramics, has specific behavior under influence of external electrical field, which involves changes of dielectric losses and impedance, depending on frequency and temperature. Dielectric properties were measured in the frequency range 20 Hz - 1 MHz. Values for permittivity (εr ranged between 140 - 430. Order of magnitude for electrical resistivity was about 106 Ωm, for impedance 104 - 108 Ω, and loss tangent had values about and greater than 0.05. Current flow through active dielectric takes place through dielectric barrier and throughout conduction bands of thin aluminum and magnesium metal films. Permittivity has nonlinear distribution and complex functional dependences because of significant nonhomogeneity of active microalloyed ceramics. Lower values of electrical resistivity are the result of complex electron and ion transfer of charge through solid phase and pores, with decreased potential barriers height, due to the influence of additives, ingredients and defects. [Projekat Ministarstva nauke Republike Srbije, br. III 45012 i br. ON 172057

Dielectric-Lined High-Gradient Accelerator Structure

Energy Technology Data Exchange (ETDEWEB)

Jay L. Hirshfield

2012-04-24

Rectangular particle accelerator structures with internal planar dielectric elements have been studied, with a view towards devising structures with lower surface fields for a given accelerating field, as compared with structures without dielectrics. Success with this concept is expected to allow operation at higher accelerating gradients than otherwise on account of reduced breakdown probabilities. The project involves studies of RF breakdown on amorphous dielectrics in test cavities that could enable high-gradient structures to be built for a future multi-TeV collider. The aim is to determine what the limits are for RF fields at the surfaces of selected dielectrics, and the resulting acceleration gradient that could be achieved in a working structure. The dielectric of principal interest in this study is artificial CVD diamond, on account of its advertised high breakdown field ({approx}2 GV/m for dc), low loss tangent, and high thermal conductivity. Experimental studies at mm-wavelengths on materials and structures for achieving high acceleration gradient were based on the availability of the 34.3 GHz third-harmonic magnicon amplifier developed by Omega-P, and installed at the Yale University Beam Physics Laboratory. Peak power from the magnicon was measured to be about 20 MW in 0.5 {micro}s pulses, with a gain of 54 dB. Experiments for studying RF high-field effects on CVD diamond samples failed to show any evidence after more than 10{sup 5} RF pulses of RF breakdown up to a tangential surface field strength of 153 MV/m; studies at higher fields were not possible due to a degradation in magnicon performance. A rebuild of the tube is underway at this writing. Computed performance for a dielectric-loaded rectangular accelerator structure (DLA) shows highly competitive properties, as compared with an existing all-metal structure. For example, comparisons were made of a DLA structure having two planar CVD diamond elements with a all-metal CERN structure HDS

Dielectric-Lined High-Gradient Accelerator Structure

International Nuclear Information System (INIS)

Hirshfield, Jay L.

2012-01-01

Rectangular particle accelerator structures with internal planar dielectric elements have been studied, with a view towards devising structures with lower surface fields for a given accelerating field, as compared with structures without dielectrics. Success with this concept is expected to allow operation at higher accelerating gradients than otherwise on account of reduced breakdown probabilities. The project involves studies of RF breakdown on amorphous dielectrics in test cavities that could enable high-gradient structures to be built for a future multi-TeV collider. The aim is to determine what the limits are for RF fields at the surfaces of selected dielectrics, and the resulting acceleration gradient that could be achieved in a working structure. The dielectric of principal interest in this study is artificial CVD diamond, on account of its advertised high breakdown field (∼2 GV/m for dc), low loss tangent, and high thermal conductivity. Experimental studies at mm-wavelengths on materials and structures for achieving high acceleration gradient were based on the availability of the 34.3 GHz third-harmonic magnicon amplifier developed by Omega-P, and installed at the Yale University Beam Physics Laboratory. Peak power from the magnicon was measured to be about 20 MW in 0.5 (micro)s pulses, with a gain of 54 dB. Experiments for studying RF high-field effects on CVD diamond samples failed to show any evidence after more than 10 5 RF pulses of RF breakdown up to a tangential surface field strength of 153 MV/m; studies at higher fields were not possible due to a degradation in magnicon performance. A rebuild of the tube is underway at this writing. Computed performance for a dielectric-loaded rectangular accelerator structure (DLA) shows highly competitive properties, as compared with an existing all-metal structure. For example, comparisons were made of a DLA structure having two planar CVD diamond elements with a all-metal CERN structure HDS operating at 30

Dielectric-breakdown tests of water at 6 MV

Directory of Open Access Journals (Sweden)

W. A. Stygar

2009-01-01

Full Text Available We have conducted dielectric-breakdown tests on water subject to a single unipolar pulse. The peak voltages used for the tests range from 5.8 to 6.8 MV; the effective pulse widths range from 0.60 to 1.1  μs; and the effective areas tested range from 1.8×10^{5} to 3.6×10^{6}  cm^{2}. The tests were conducted on water-insulated coaxial capacitors. The two electrodes of each capacitor have outer and inner radii of 99 and 56 cm, respectively. Results of the tests are consistent with predictions of the water-dielectric-breakdown relation developed in [Phys. Rev. ST Accel. Beams 9, 070401 (2006PRABFM1098-440210.1103/PhysRevSTAB.9.070401].

Decomposition of acetaminophen in water by a gas phase dielectric barrier discharge plasma combined with TiO2-rGO nanocomposite: Mechanism and degradation pathway

Energy Technology Data Exchange (ETDEWEB)

Zhang, Guyu; Sun, Yabing, E-mail: sybnju@163.com; Zhang, Chunxiao; Yu, Zhongqing

2017-02-05

Highlights: • Graphene Oxide-based catalyst was first applied with dielectric barrier discharge plasma. • The TiO{sub 2}-rGO showed efficient synergistic effect with gas phase dielectric barrier discharge plasma. • The property changes of TiO{sub 2}-rGO nanocomposite after plasma treatment were characterized. • The mechanism and possible pathways of APAP degradation in plasma/TiO{sub 2}-rGO system were proposed. - Abstract: Acetaminophen (APAP) served as the model pollutant to evaluate the feasibility of pollutant removal by gas phase dielectric barrier discharge plasma combined with the titanium dioxide-reduced Graphene Oxide (TiO{sub 2}-rGO) nanocomposite. TiO{sub 2}-rGO nanocomposite was prepared using the modified hydrothermal method and characterized by TEM and XPS before and after plasma process. The results indicated that the APAP degradation efficiency was significantly improved to 92% after 18 min of discharge plasma treatment coupling 0.25 g L{sup −1} TiO{sub 2}-rGO 5% wt at 18 kV, compared with the plasma alone and plasma combined with P25 TiO{sub 2}. The degradation mechanism for APAP in this system was studied by investigating the effects of the operational variables (e.g. discharge voltage and pH value) and the amount of the generated active species; and the results showed that O{sub 3} and H{sub 2}O{sub 2} yields were influenced notably by adding TiO{sub 2}-rGO. Also, it was observed that, compared with unused TiO{sub 2}-rGO, the photocatalytic performance of used TiO{sub 2}-rGO declined after several recirculation times due to the further reduction of Graphene Oxide in plasma system. Finally, intermediate products were analyzed by UV–vis spectrometry and HPLC/MS, and possible transformation pathways were identified with the support of theoretically calculating the frontier electron density of APAP.

Encapsulation methods and dielectric layers for organic electrical devices

Science.gov (United States)

Blum, Yigal D; Chu, William Siu-Keung; MacQueen, David Brent; Shi, Yijan

2013-07-02

The disclosure provides methods and materials suitable for use as encapsulation barriers and dielectric layers in electronic devices. In one embodiment, for example, there is provided an electroluminescent device or other electronic device with a dielectric layer comprising alternating layers of a silicon-containing bonding material and a ceramic material. The methods provide, for example, electronic devices with increased stability and shelf-life. The invention is useful, for example, in the field of microelectronic devices.

Center for dielectric studies

Science.gov (United States)

Cross, L. E.; Newnham, R. E.; Biggers, J. V.

1984-05-01

This report focuses upon the parts of the Center program which have drawn most extensively upon Navy funds. In the basic study of polarization processes in high K dielectrics, major progress has been made in understanding the mechanisms in relaxor ferroelectric in the perovskite structure families. A new effort is also being mounted to obtain more precise evaluation of the internal stress effects in fine grained barium titanate. Related to reliability, studies of the effects of induced macro-defects are described, and preparation for the evaluation of space charge by internal potential distribution measurements discussed. To develop new processing methods for very thin dielectric layers, a new type of single barrier layer multilayer is discussed, and work on the thermal evaporation of oriented crystalline antimony sulphur iodide describe.

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

International Nuclear Information System (INIS)

Chen Huixia; Xiu Zhilong; Bai Fengwu

2014-01-01

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

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

Science.gov (United States)

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.

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

International Nuclear Information System (INIS)

Liang Wenjun; Li Jian; Li Jie; Jin Yuquan

2009-01-01

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. BaTiO 3 reactor had the highest toluene removal efficiency among the reactors. For NaNO 2 reactor, the highest EY could reach 17.0 mg/kWh to a certain extent.

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

Science.gov (United States)

Chen, Huixia; Xiu, Zhilong; Bai, Fengwu

2014-06-01

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

Adsorbability Enhancement of Macroporous Resin by Dielectric Barrier Discharge Plasma Treatment to Phenol in Water

Directory of Open Access Journals (Sweden)

Shoufeng Tang

2016-01-01

Full Text Available In order to enhance the adsorption efficiency and economize the use of macroporous resin, we have treated it with the dielectric barrier discharge (DBD plasma to improve its adsorbing capacity for phenol. The effects of operation conditions, for instance, applied voltage, treated time, and air flow rate on resin, were investigated by adsorption kinetics and isotherms. Results showed that the adsorption data were in good agreement with the pseudo-second-order and Freundlich equation. Experimental results showed that the modified resin was 156.5 mg/g and 39.2% higher than the untreated sample, when the modified conditions were conducted for discharge voltage 20 kV, treatment time 45 min, and air flow rate 1.2 L/min. The resin was characterized by FTIR and nitrogen adsorption isotherms before and after the DBD processes. It was found that the reason for the enhancement of resin adsorbability was attributed to the DBD plasma changing the surface physical and chemical structure.

Filamentary and diffuse barrier discharges

International Nuclear Information System (INIS)

Kogelschatz, U.

2001-01-01

Barrier discharges, sometimes also referred to as dielectric-barrier discharges or silent discharges, are characterized by the presence of at least one insulating layer in contact with the discharge between two planar or cylindrical electrodes connected to an ac power supply. The main advantage of this type of electrical discharge is, that non-equilibrium plasma conditions in atmospheric-pressure gases can be established in an economic and reliable way. This has led to a number of important applications including industrial ozone generation, surface modification of polymers, plasma chemical vapor deposition, excitation of CO 2 lasers, excimer lamps and, most recently, large-area flat plasma display panels. Depending on the application, the width of the discharge gap can range from less than 0.1 mm to about 100 mm and the applied frequency from below line frequency to several gigahertz. Typical materials used for the insulating layer (dielectric barrier) are glass, quartz, ceramics but also thin enamel or polymer layers

The effect of O2 in a humid O2/N2/NOx gas mixture on NOx and N2O remediation by an atmospheric pressure dielectric barrier discharge

DEFF Research Database (Denmark)

Teodoru, Steluta; Kusano, Yukihiro; Bogaerts, Annemie

2012-01-01

A numerical model for NxOy remediation in humid air plasma produced with a dielectric barrier discharge at atmospheric pressure is presented. Special emphasis is given to NO2 and N2O reduction with the decrease of O2 content in the feedstock gas. A detailed reaction mechanism including electronic...

Low operating voltage InGaZnO thin-film transistors based on Al2O3 high-k dielectrics fabricated using pulsed laser deposition

International Nuclear Information System (INIS)

Geng, G. Z.; Liu, G. X.; Zhang, Q.; Shan, F. K.; Lee, W. J.; Shin, B. C.; Cho, C. R.

2014-01-01

Low-voltage-driven amorphous indium-gallium-zinc-oxide (IGZO) thin-film transistors (TFTs) with an Al 2 O 3 dielectric were fabricated on a Si substrate by using pulsed laser deposition. Both Al 2 O 3 and IGZO thin films are amorphous, and the thin films have very smooth surfaces. The Al 2 O 3 gate dielectric exhibits a very low leakage current density of 1.3 x 10 -8 A/cm 2 at 5 V and a high capacitance density of 60.9 nF/cm 2 . The IGZO TFT with a structure of Ni/IGZO/Al 2 O 3 /Si exhibits high performance with a low threshold voltage of 1.18 V, a high field effect mobility of 20.25 cm 2 V -1 s -1 , an ultra small subthreshold swing of 87 mV/decade, and a high on/off current ratio of 3 x 10 7 .

Experimental demonstration of dielectric structure based two beam acceleration

International Nuclear Information System (INIS)

Gai, W.; Conde, M. E.; Konecny, R.; Power, J. G.; Schoessow, P.; Sun, X.; Zou, P.

2000-01-01

We report on the experimental results of the dielectric based two beam accelerator (step-up transformer). By using a single high charge beam, we have generated and extracted a high power RF pulse from a 7.8 GHz primary dielectric structure and then subsequently transferred to a second accelerating structure with higher dielectric constant and smaller transverse dimensions. We have measured the energy change of a second (witness) beam passing through the acceleration stage. The measured gradient is >4 times the deceleration gradient. The detailed experiment of set-up and results of the measurements are dimmed. Future plans for the development of a 100 MeV demonstration accelerator based on this technique is presented

Experimental demonstration of dielectric structure based two beam acceleration.

Energy Technology Data Exchange (ETDEWEB)

Gai, W.; Conde, M. E.; Konecny, R.; Power, J. G.; Schoessow, P.; Sun, X.; Zou, P.

2000-11-28

We report on the experimental results of the dielectric based two beam accelerator (step-up transformer). By using a single high charge beam, we have generated and extracted a high power RF pulse from a 7.8 GHz primary dielectric structure and then subsequently transferred to a second accelerating structure with higher dielectric constant and smaller transverse dimensions. We have measured the energy change of a second (witness) beam passing through the acceleration stage. The measured gradient is >4 times the deceleration gradient. The detailed experiment of set-up and results of the measurements are dimmed. Future plans for the development of a 100 MeV demonstration accelerator based on this technique is presented.

Generation of reactive species in atmospheric pressure dielectric barrier discharge with liquid water

Science.gov (United States)

Zelong, ZHANG; Jie, SHEN; Cheng, CHENG; Zimu, XU; Weidong, XIA

2018-04-01

Atmospheric pressure helium/water dielectric barrier discharge (DBD) plasma is used to investigate the generation of reactive species in a gas-liquid interface and in a liquid. The emission intensity of the reactive species is measured by optical emission spectroscopy (OES) with different discharge powers at the gas-liquid interface. Spectrophotometry is used to analyze the reactive species induced by the plasma in the liquid. The concentration of OH radicals reaches 2.2 μm after 3 min of discharge treatment. In addition, the concentration of primary long-lived reactive species such as H2O2, {{{{NO}}}3}- and O3 are measured based on plasma treatment time. After 5 min of discharge treatment, the concentration of H2O2, {{{{NO}}}3}-, and O3 increased from 0 mg · L-1 to 96 mg · L-1, 19.5 mg · L-1, and 3.5 mg · L-1, respectively. The water treated by plasma still contained a considerable concentration of reactive species after 6 h of storage. The results will contribute to optimizing the DBD plasma system for biological decontamination.

Numerical Investigation of Scattering from a Surface Dielectric Barrier Discharge Actuator under Atmospheric Pressure

Directory of Open Access Journals (Sweden)

Yuna Kim

2018-01-01

Full Text Available Surface dielectric barrier discharge (SDBD, which is widely used to control turbulence in aerodynamics, has a significant effect on the radar cross-section (RCS. A four-way linearly synthesized SDBD air plasma actuator is designed to bolster the plasma effects on electromagnetic waves. The diffraction angle is calculated to predict the RCS because of the periodic structure of staggered electrodes. The simplified plasma modeling is utilized to calculate the inhomogeneous surface plasma distribution. Monostatic RCS shows the diffraction in the plane perpendicular to the electrode array and the notable distortion by plasma. In comparison, the overall pattern is maintained in the parallel plane with minor plasma effects. The trends also appear in the bistatic RCS, which has a significant difference in the observation plane perpendicular to the electrodes. The peaks by Bragg’s diffraction are shown, and the RCS is reduced by 10 dB in a certain range by the plasma effect. The diffraction caused by the actuator and the inhomogeneous air plasma should be considered in designing an SDBD actuator for a wide range of application.

Removal of caffeine from water by combining dielectric barrier discharge (DBD plasma with goethite

Directory of Open Access Journals (Sweden)

Jian Wang

2017-07-01

Full Text Available In this research, dielectric barrier discharge plasma was developed to cooperate with goethite for removing caffeine in aqueous solution. Goethite was characterized by X-ray diffraction and scanning electron microscopy. The effects of input power, initial concentration and catalysts concentration on the removal efficiency of caffeine were evaluated. Furthermore, the degradation pathways of caffeine were also discussed preliminarily. In the case of caffeine concentration at 50 mg L−1, the degradation efficiency of caffeine was improved from 41% to 94% after 24 min on the conditions of input power of 75 W by combining goethite catalysts (2.5 g L−1, while the energy efficiency could be enhanced 1.6–2.3 times compared to the single DBD reactor. The reaction mechanism experiments demonstrated that attack by hydroxyl radical and ozone was the main degradation process of caffeine in aqueous solution. These studies also provided a theoretical and practical basis for the application of DBD-goethite in treatment of caffeine from water.

Subluminal and superluminal pulse propagation in inhomogeneous media of nonspherical particles

International Nuclear Information System (INIS)

Ma Yu; Gao Lei

2006-01-01

We study the pulse propagation through a metal/dielectric composites of nonspherical particles enclosed by two gold mirrors. To account for the shape effect, we first adopt Maxwell-Garnett type approximation to obtain the effective dielectric function of composites. Based on the group index, phase time and pulse shape calculations, we find that the particles' shape (characterized by the depolarization factor) plays an important role in determining the subluminal and superluminal pulse propagations through the system. When the inclusions' shape is not spherical, it is possible to observe significant superluminal behavior of the pulse propagation, although the volume fraction is the same. The shape-dependent critical volume fraction is predicted, above which superluminal propagation appears. Furthermore, the Hartman effect in such a system is also investigated

Pulse-height response of silicon surface-barrier detectors to high-energy heavy ions

International Nuclear Information System (INIS)

Smith, G.D.

1973-01-01

The pulse-height defect (PHD) of high-energy heavy ions in silicon surface-barrier detectors can be divided into three components: (1) energy loss in the gold-surface layer, (2) a nuclear-stopping defect, and (3) a defect due to recombination of electron-hole pairs in the plasma created by the heavy ion. The plasma recombination portion of the PHD was the subject of this study using the variation of the PHD with (1) the angle of incidence of incoming heavy ions, and (2) changes in the detector bias. The Tandem Van de Graaff accelerator at Argonne National Laboratory was used to produce scattered beam ions ( 32 S, 35 Cl) and heavy target recoils (Ni, Cu, 98 Mo, Ag, Au) at sufficient energies to produce a significant recombination defect. The results confirm the existence of a recombination zone at the front surface of these detectors and the significance of plasma recombination as a portion of the pulse-height defect. (Diss. Abstr. Int., B)

Rectifying the Optical-Field-Induced Current in Dielectrics: Petahertz Diode.

Science.gov (United States)

Lee, J D; Yun, Won Seok; Park, Noejung

2016-02-05

Investigating a theoretical model of the optical-field-induced current in dielectrics driven by strong few-cycle laser pulses, we propose an asymmetric conducting of the current by forming a heterojunction made of two distinct dielectrics with a low hole mass (m_{h}^{*}≪m_{e}^{*}) and low electron mass (m_{e}^{*}≪m_{h}^{*}), respectively. This proposition introduces the novel concept of a petahertz (10^{15}  Hz) diode to rectify the current in the petahertz domain, which should be a key ingredient for the electric signal manipulation of future light-wave electronics. Further, we suggest the candidate dielectrics for the heterojunction.

Device for detecting imminent failure of high-dielectric stress capacitors. [Patent application

Science.gov (United States)

McDuff, G.G.

1980-11-05

A device is described for detecting imminent failure of a high-dielectric stress capacitor utilizing circuitry for detecting pulse width variations and pulse magnitude variations. Inexpensive microprocessor circuitry is utilized to make numerical calculations of digital data supplied by detection circuitry for comparison of pulse width data and magnitude data to determine if preselected ranges have been exceeded, thereby indicating imminent failure of a capacitor. Detection circuitry may be incorporated in transmission lines, pulse power circuitry, including laser pulse circuitry or any circuitry where capacitors or capacitor banks are utilized.

Diffusion barriers for Cu metallisation in Si integrated circuits : deposition and related thin film properties

NARCIS (Netherlands)

van Nieuwkasteele-Bystrova, Svetlana Nikolajevna

2004-01-01

In modern integrated circuits with Cu interconnects a diffusion barrier is used between the dielectric and Cu in order to prevent diffusion of Cu through the dielectrics. The choice of such a barrier requires a material exploration and a study of the material reactivity with both Cu and the

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

Science.gov (United States)

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.

A sensitive gas chromatography detector based on atmospheric pressure chemical ionization by a dielectric barrier discharge.

Science.gov (United States)

Kirk, Ansgar T; Last, Torben; Zimmermann, Stefan

2017-02-03

In this work, we present a novel concept for a gas chromatography detector utilizing an atmospheric pressure chemical ionization which is initialized by a dielectric barrier discharge. In general, such a detector can be simple and low-cost, while achieving extremely good limits of detection. However, it is non-selective apart from the use of chemical dopants. Here, a demonstrator manufactured entirely from fused silica capillaries and printed circuit boards is shown. It has a size of 75×60×25mm 3 and utilizes only 2W of power in total. Unlike other known discharge detectors, which require high-purity helium, this detector can theoretically be operated using any gas able to form stable ion species. Here, purified air is used. With this setup, limits of detection in the low parts-per-billion range have been obtained for acetone. Copyright © 2017 Elsevier B.V. All rights reserved.

Microdosimetric study for nanosecond pulsed electric fields on a cell circuit model with nucleus.

Science.gov (United States)

Denzi, Agnese; Merla, Caterina; Camilleri, Paola; Paffi, Alessandra; d'Inzeo, Guglielmo; Apollonio, Francesca; Liberti, Micaela

2013-10-01

Recently, scientific interest in electric pulses, always more intense and shorter and able to induce biological effects on both plasma and nuclear membranes, has greatly increased. Hence, microdosimetric models that include internal organelles like the nucleus have assumed increasing importance. In this work, a circuit model of the cell including the nucleus is proposed, which accounts for the dielectric dispersion of all cell compartments. The setup of the dielectric model of the nucleus is of fundamental importance in determining the transmembrane potential (TMP) induced on the nuclear membrane; here, this is demonstrated by comparing results for three different sets of nuclear dielectric properties present in the literature. The results have been compared, even including or disregarding the dielectric dispersion of the nucleus. The main differences have been found when using pulses shorter than 10 ns. This is due to the fact that the high spectral components of the shortest pulses are differently taken into account by the nuclear membrane transfer functions computed with and without nuclear dielectric dispersion. The shortest pulses are also the most effective in porating the intracellular structures, as confirmed by the time courses of the TMP calculated across the plasma and nuclear membranes. We show how dispersive nucleus models are unavoidable when dealing with pulses shorter than 10 ns because of the large spectral contents arriving above 100 MHz, i.e., over the typical relaxation frequencies of the dipolar mechanism of the molecules constituting the nuclear membrane and the subcellular cell compartments.

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

Science.gov (United States)

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.

Study of dielectric materials irradiated with electron beam by using the Pulsed Electro-Acoustic (PEA) method

International Nuclear Information System (INIS)

Nguyen, Xuan Truong

2014-01-01

Dielectric materials are frequently used as electrical insulators in spatial applications. Due to their dielectric nature, these dielectrics are likely to accumulate electric charges during their service. Under certain critical conditions, these internal or surface space charges can lead to an electrostatic surface discharge. To understand these phenomena, an experimental device has been developed in the laboratory. This device allows us to simulate the electronic irradiation conditions encountered in space. The aim of our study is to characterize the electrical behavior of insulating materials irradiated by electron beam, to investigate charge storage and transport phenomena and anticipate electrostatic discharges. In this work, the device based on the Pulsed Electro-Acoustic (PEA) technique has been chosen. It has been implanted in the irradiation chamber. It allows us to obtain the spatial distribution of charges injected between two periods of irradiation and during relaxation. However the PEA method offers a limited resolution and does not allow the detection of injected charges when they are too close to the surface. First, we performed a parameters signal processing analysis that we will call the spreading factor and the resolution factor. The preliminary study post-irradiation in air of experimental measurements showed that the resolution factor choice is important for the analysis and interpretation of the signal when the space charge is localized near the surface. Then, a comparison to the spreading parameter used in some deconvolution technique was established. In the second time, space charge distribution measurements in vacuum have been carried out on Poly Tetra Fluoro Ethylene (PTFE) films irradiated by an electron beam in the range [10-100] keV. Results from irradiation periods with increasing energies [10 keV → 100 keV] of the electron beam have been compared with results from irradiation periods with decreasing energies [100 keV → 10 keV]. In

Experimental Investigation of Pulsed Nanosecond Streamer Discharges for CO2 Reforming

Science.gov (United States)

Pachuilo, Michael; Levko, Dima; Raja, Laxminarayan; Varghese, Philip

2016-09-01

Rapid global industrialization has led to an increase in atmospheric greenhouse gases, specifically carbon dioxide levels. Plasmas present a great potential for efficient reforming of greenhouse gases. There are several plasma discharges which have been reported for reforming process: dielectric barrier discharges (DBD), microwave discharges, and glide-arcs. Microwave discharges have CO2 conversion energy efficiency of up to 40% at atmospheric conditions, while glide-arcs have 43% and DBD 2-10%. In our study, we analyze a single nanosecond pulsed cathode directed streamer discharge in CO2 at atmospheric pressure and temperature. We have conducted time resolved imaging with spectral bandpass filters of a streamer discharge with an applied negative polarity pulse. The image sequences have been correlated to the applied voltage and current pulses. From the spectral filters we can determine where spatially and temporally excited species are formed. In this talk we report on spectroscopic studies of the discharge and estimate plasma properties such as temperature and density of excited species and electrons. Furthermore, we report on the effects of pulse polarity as well as anodic streamer discharges on the CO2 conversion efficiency. Finally, we will focus on the effects of vibrational excitation on carbon dioxide reforming efficiency for streamer discharges. Our experimental results will be compared with an accompanying plasma computational model studies.

Status of the upgraded version of the NRL GAMBLE II pulse power generator

International Nuclear Information System (INIS)

Boller, J.R.; Burton, J.K.; Shipman, J.D. Jr.

1979-01-01

The GAMBLE II water dielectric pulse power generator, in 1970, was the forerunner of the high energy (> 50 kJ) class of water dielectric generators. It has been redesigned internally to make maximum use of its original outer conductor shell and to optimize it for the positive polarity mode of operation for positive ion beam experimentation. The new design also initiates the use of an oil dielectric multi-channel switch at the output of the pulse forming line. This switch, because of its low capacitance, eliminates the need for an extra prepulse switch. The upgraded version has been tested up to power and energy levels which are nearly twice the original

Origin of colossal dielectric permittivity of rutile Ti₀.₉In₀.₀₅Nb₀.₀₅O₂: single crystal and polycrystalline.

Science.gov (United States)

Song, Yongli; Wang, Xianjie; Sui, Yu; Liu, Ziyi; Zhang, Yu; Zhan, Hongsheng; Song, Bingqian; Liu, Zhiguo; Lv, Zhe; Tao, Lei; Tang, Jinke

2016-02-12

In this paper, we investigated the dielectric properties of (In + Nb) co-doped rutile TiO2 single crystal and polycrystalline ceramics. Both of them showed colossal, up to 10(4), dielectric permittivity at room temperature. The single crystal sample showed one dielectric relaxation process with a large dielectric loss. The voltage-dependence of dielectric permittivity and the impedance spectrum suggest that the high dielectric permittivity of single crystal originated from the surface barrier layer capacitor (SBLC). The impedance spectroscopy at different temperature confirmed that the (In + Nb) co-doped rutile TiO2 polycrystalline ceramic had semiconductor grains and insulating grain boundaries, and that the activation energies were calculated to be 0.052 eV and 0.35 eV for grain and grain boundary, respectively. The dielectric behavior and impedance spectrum of the polycrystalline ceramic sample indicated that the internal barrier layer capacitor (IBLC) mode made a major contribution to the high ceramic dielectric permittivity, instead of the electron-pinned defect-dipoles.

Influence of shock wave propagation on dielectric barrier discharge plasma actuator performance

International Nuclear Information System (INIS)

Erfani, Rasool; Zare-Behtash, Hossein; Kontis, Konstantinos

2012-01-01

Interest in plasma actuators as active flow control devices is growing rapidly due to their lack of mechanical parts, light weight and high response frequency. Although the flow induced by these actuators has received much attention, the effect that the external flow has on the performance of the actuator itself must also be considered, especially the influence of unsteady high-speed flows which are fast becoming a norm in the operating flight envelopes. The primary objective of this study is to examine the characteristics of a dielectric barrier discharge (DBD) plasma actuator when exposed to an unsteady flow generated by a shock tube. This type of flow, which is often used in different studies, contains a range of flow regimes from sudden pressure and density changes to relatively uniform high-speed flow regions. A small circular shock tube is employed along with the schlieren photography technique to visualize the flow. The voltage and current traces of the plasma actuator are monitored throughout, and using the well-established shock tube theory the change in the actuator characteristics are related to the physical processes which occur inside the shock tube. The results show that not only is the shear layer outside of the shock tube affected by the plasma but the passage of the shock front and high-speed flow behind it also greatly influences the properties of the plasma. (paper)

Characterization of a dielectric phantom for high-field magnetic resonance imaging applications

Energy Technology Data Exchange (ETDEWEB)

Duan, Qi, E-mail: Qi.Duan@nih.gov; Duyn, Jeff H.; Gudino, Natalia; Zwart, Jacco A. de; Gelderen, Peter van [Advanced MRI Section, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892 (United States); Sodickson, Daniel K.; Brown, Ryan [The Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, New York 10016 (United States)

2014-10-15

Purpose: In this work, a generic recipe for an inexpensive and nontoxic phantom was developed within a range of biologically relevant dielectric properties from 150 MHz to 4.5 GHz. Methods: The recipe includes deionized water as the solvent, NaCl to primarily control conductivity, sucrose to primarily control permittivity, agar–agar to gel the solution and reduce heat diffusivity, and benzoic acid to preserve the gel. Two hundred and seventeen samples were prepared to cover the feasible range of NaCl and sucrose concentrations. Their dielectric properties were measured using a commercial dielectric probe and were fitted to a 3D polynomial to generate a recipe describing the properties as a function of NaCl concentration, sucrose concentration, and frequency. Results: Results indicated that the intuitive linear and independent relationships between NaCl and conductivity and between sucrose and permittivity are not valid. A generic polynomial recipe was developed to characterize the complex relationship between the solutes and the resulting dielectric values and has been made publicly available as a web application. In representative mixtures developed to mimic brain and muscle tissue, less than 2% difference was observed between the predicted and measured conductivity and permittivity values. Conclusions: It is expected that the recipe will be useful for generating dielectric phantoms for general magnetic resonance imaging (MRI) coil development at high magnetic field strength, including coil safety evaluation as well as pulse sequence evaluation (including B{sub 1}{sup +} mapping, B{sub 1}{sup +} shimming, and selective excitation pulse design), and other non-MRI applications which require biologically equivalent dielectric properties.

Scattering of electromagnetic pulses by metal nanospheres in the vicinity of a Fano-like resonance

International Nuclear Information System (INIS)

Astapenko, V.A.; Svita, S.Yu.

2015-01-01

In the work, radiation scattering by metal nanospheres in a dielectric matrix in case of ultrashort and long electromagnetic pulses is studied theoretically. Spectral efficiencies of backward and forward scattering by silver nanospheres in glass are calculated with the use of experimental data on the dielectric permittivity of silver. The presence of Fano-like resonances in spectral dependences of scattering efficiency caused by interference of dipole and quadrupole scatterings is shown. Backward and forward scattering of ultrashort pulses is calculated and analyzed. The obtained dependences of the total probability of scattering (during all time of the action of a pulse) on pulse duration demonstrate an essential distinction between an ultrashort case and a long pulse limit

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

DEFF Research Database (Denmark)

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

2011-01-01

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

Dependence of Initial Oxygen Concentration on Ozone Yield Using Inductive Energy Storage System Pulsed Power Generator

Science.gov (United States)

Go, Tomio; Tanaka, Yasushi; Yamazaki, Nobuyuki; Mukaigawa, Seiji; Takaki, Koichi; Fujiwara, Tamiya

Dependence of initial oxygen concentration on ozone yield using streamer discharge reactor driven by an inductive energy storage system pulsed power generator is described in this paper. Fast recovery type diodes were employed as semiconductor opening switch to interrupt a circuit current within 100 ns. This rapid current change produced high-voltage short pulse between a secondary energy storage inductor. The repetitive high-voltage short pulse was applied to a 1 mm diameter center wire electrode placed in a cylindrical pulse corona reactor. The streamer discharge successfully occurred between the center wire electrode and an outer cylinder ground electrode of 2 cm inner diameter. The ozone was produced with the streamer discharge and increased with increasing pulse repetition rate. The ozone yield changed in proportion to initial oxygen concentration contained in the injected gas mixture at 800 ns forward pumping time of the current. However, the decrease of the ozone yield by decreasing oxygen concentration in the gas mixture at 180 ns forward pumping time of the current was lower than the decrease at 800 ns forward pumping time of the current. This dependence of the initial oxygen concentration on ozone yield at 180 ns forward pumping time is similar to that of dielectric barrier discharge reactor.

Studies on surface grafting of AAc/SSS binary monomers onto polytetrafluoroethylene by dielectric barrier discharge initiation

International Nuclear Information System (INIS)

Xi Zhenyu; Xu Youyi; Zhu Liping; Liu Fu; Zhu Baoku

2008-01-01

Polytetrafluoroethylene (PTFE) films were pre-treated by dielectric barrier discharge in atmospheric pressure with air as carrier gas. And then the hydrophilic sulfonate groups were introduced by the single step grafting method with binary monomer solution of acrylic acid (AAc) and sodium 4-styrenesulfonate (SSS). The effects of binary monomer ratio, reaction solution concentration and polymerization time on the degree of grafting were investigated. The surface chemical change was determined by Fourier transform infrared attenuated total reflection spectroscopy (FTIR-ATR) and X-ray photoelectron spectroscopy (XPS). Morphological changes on the film surface were described using field emitting scanning electron microscopy (SEM) and atomic force microscopy (AFM). The surface hydrophilicity of the modified film was characterized through water contact angle measurement. It was found that the water contact angle of the film surface reduced significantly when compared with the original one, indicating the introduction of hydrophilic groups and improvement of the surface hydrophilicity

Hierarchical modeling of plasma and transport phenomena in a dielectric barrier discharge reactor

Science.gov (United States)

Bali, N.; Aggelopoulos, C. A.; Skouras, E. D.; Tsakiroglou, C. D.; Burganos, V. N.

2017-12-01

A novel dual-time hierarchical approach is developed to link the plasma process to macroscopic transport phenomena in the interior of a dielectric barrier discharge (DBD) reactor that has been used for soil remediation (Aggelopoulos et al 2016 Chem. Eng. J. 301 353-61). The generation of active species by plasma reactions is simulated at the microseconds (µs) timescale, whereas convection and thermal conduction are simulated at the macroscopic (minutes) timescale. This hierarchical model is implemented in order to investigate the influence of the plasma DBD process on the transport and reaction mechanisms during remediation of polluted soil. In the microscopic model, the variables of interest include the plasma-induced reactive concentrations, while in the macroscopic approach, the temperature distribution, and the velocity field both inside the discharge gap and within the polluted soil material as well. For the latter model, the Navier-Stokes and Darcy Brinkman equations for the transport phenomena in the porous domain are solved numerically using a FEM software. The effective medium theory is employed to provide estimates of the effective time-evolving and three-phase transport properties in the soil sample. Model predictions considering the temporal evolution of the plasma remediation process are presented and compared with corresponding experimental data.

Removal of formaldehyde from gas streams via packed-bed dielectric barrier discharge plasmas

International Nuclear Information System (INIS)

Ding Huixian; Zhu Aimin; Yang Xuefeng; Li Cuihong; Xu Yong

2005-01-01

Formaldehyde is a major indoor air pollutant and can cause serious health disorders in residents. This work reports the removal of formaldehyde from gas streams via alumina-pellet-filled dielectric barrier discharge plasmas at atmospheric pressure and 70 deg. C. With a feed gas mixture of 140 ppm HCHO, 21.0% O 2 , 1.0% H 2 O in N 2 , ∼92% of formaldehyde can be effectively destructed at GHSV (gas flow volume per hour per discharge volume) of 16 500 h -1 and E in = 108 J l -1 . An increase in the specific surface area of the alumina pellets enhances the HCHO removal, and this indicates that the adsorbed HCHO species may have a lower C-H bond breakage energy. Based on an examination of the influence of gas composition on the removal efficiency, the primary destruction pathways, besides the reactions initiated by discharge-generated radicals, such as O, H, OH and HO 2 , may include the consecutive dissociations of HCHO molecules and HCO radicals through their collisions with vibrationally- and electronically-excited metastable N 2 species. The increase of O 2 content in the inlet gas stream is able to diminish the CO production and to promote the formation of CO 2 via O-atom or HO 2 -radical involved reactions

Improvement of wettability and absorbancy of textile using atmospheric pressure dielectric barrier discharge

Science.gov (United States)

Ghimire, Bhagirath; Subedi, Deepak Prasad; Khanal, Raju

2017-08-01

In this study, cotton textile samples, commonly used in making quilt covers were subjected to atmospheric pressure dielectric barrier discharge treatment to study their surface wettability and absorbancy. Samples were treated in the discharge using a rotatory mechanism and the effects of plasma treatment were examined by contact angle measurement and weight measurement. Air plasma treatment was successful in incorporating hydrophilic functional groups on the textile surface due to which wettability as well as absorbancy immediately after the treatment were highly improved. Effects of plasma treatment started to appear only after 20 cycles (9 mins) and got saturated after 24 cycles (10.8 mins) of treatment. The contact angle reduced from 137 ° (untreated sample) to a value less than 30 ° while absorbancy increased by more than two times as compared to untreated sample. Also, the aging behavior of the plasma treated samples were studied for about a week after plasma treatment. It was observed that the induced oxygen containing groups re-oriented into the bulk of the material during their storage in the environment due to which initial properties of the samples recovered gradually. Our results indicate that low temperature plasma can be successfully applied to modify the properties of textiles and textile industries could utilize this by standardization.

Silicon oxide barrier films deposited on PET foils in pulsed plasmas: influence of substrate bias on deposition process and film properties

International Nuclear Information System (INIS)

Steves, S; Bibinov, N; Awakowicz, P; Ozkaya, B; Liu, C-N; Ozcan, O; Grundmeier, G

2013-01-01

A widely used plastic for packaging, polyethylene terephtalate (PET) offers limited barrier properties against gas permeation. For many applications of PET (from food packaging to micro electronics) improved barrier properties are essential. A silicon oxide barrier coating of PET foils is applied by means of a pulsed microwave driven low-pressure plasma. While the adjustment of the microwave power allows for a control of the ion production during the plasma pulse, a substrate bias controls the energy of ions impinging on the substrate. Detailed analysis of deposited films applying oxygen permeation measurements, x-ray photoelectron spectroscopy and atomic force microscopy are correlated with results from plasma diagnostics describing the deposition process. The influence of a change in process parameters such as gas mixture and substrate bias on the gas temperature, electron density, mean electron energy, ion energy and the atomic oxygen density is studied. An additional substrate bias results in an increase in atomic oxygen density up to a factor of 6, although plasma parameter such as electron density of n e = 3.8 ± 0.8 × 10 17 m −3 and electron temperature of k B T e = 1.7 ± 0.1 eV are unmodified. It is shown that atomic oxygen densities measured during deposition process higher than n O = 1.8 × 10 21 m −3 yield in barrier films with a barrier improvement factor up to 150. Good barrier films are highly cross-linked and show a smooth morphology. (paper)

Optical design for increased interaction length in a high gradient dielectric laser accelerator

OpenAIRE

Cesar, D.; Maxson, J.; Musumeci, P.; Shen, X.; England, R. J.; Wootton, K. P.

2018-01-01

We present a methodology for designing and measuring pulse front tilt in an ultrafast laser for use in dielectric laser acceleration. Previous research into dielectric laser accelerating modules has focused on measuring high accelerating gradients in novel structures, but has done so only for short electron-laser coupling lengths. Here we demonstrate an optical design to extend the laser-electron interaction to 1mm.

Control of stationary crossflow modes in swept Hiemenz flows with dielectric barrier discharge plasma actuators

Science.gov (United States)

Wang, Zhefu; Wang, Liang; Fu, Song

2017-09-01

Sensitivity analyses and non-linear parabolized stability equations are solved to provide a computational assessment of the potential use of a Dielectric Barrier Discharge (DBD) plasma actuator for a prolonging laminar region in swept Hiemenz flow. The derivative of the kinetic energy with respect to the body force is deduced, and its components in different directions are defined as sensitivity functions. The results of sensitivity analyses and non-linear parabolized stability equations both indicate that the introduction of a body force as the plasma actuator at the bottom of a crossflow vortex can mitigate instability to delay flow transition. In addition, the actuator is more effective when placed more upstream until the neutral point. In fact, if the actuator is sufficiently close to the neutral point, it is likely to act as a strong disturbance over-riding the natural disturbance and dominating transition. Different operating voltages of the DBD actuators are tested, resulting in an optimal practice for transition delay. The results demonstrate that plasma actuators offer great potential for transition control.

Dynamic model based on voltage transfer curve for pattern formation in dielectric barrier glow discharge

Energy Technology Data Exchange (ETDEWEB)

Li, Ben; He, Feng; Ouyang, Jiting, E-mail: jtouyang@bit.edu.cn [School of Physics, Beijing Institute of Technology, Beijing 100081 (China); Duan, Xiaoxi [Research Center of Laser Fusion, CAEP, Mianyang 621900 (China)

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.

Dielectric barrier discharge micro-plasma emission spectrometry for the detection of acetone in exhaled breath.

Science.gov (United States)

Yang, Ting; Gao, Dong-Xue; Yu, Yong-Liang; Chen, Ming-Li; Wang, Jian-Hua

2016-01-01

Acetone is a predominant volatile organic compound (VOC) in the exhaled breath and a promising biomarker for diabetes and ketoacidosis. A non-thermal micro-plasma generated in a planar dielectric barrier discharge (DBD) is used as a radiation source for the excitation of gaseous acetone followed by its quantification with optical emission spectrometry (OES). Gaseous acetone can be directly sampled, while liquid acetone is evaporated by heated tungsten coil and then introduced into the DBD micro-plasma by a helium carrier flow for performing optical emission and detection at a 519 nm emission line. In the present study, the exhaled breath is collected and transferred into aqueous medium for sampling. With a sampling volume of 7 μL in a micro-drop, a linear range of 40-1600 mg L(-1) is obtained along with a detection limit of 44 ng and a precision of 5.7% RSD. The present system is successfully applied to the determination of breath acetone for both diabetic patients and healthy volunteers. Copyright © 2015 Elsevier B.V. All rights reserved.

Cold excitation and determination of hydrogen sulfide by dielectric barrier discharge molecular emission spectrometry.

Science.gov (United States)

Wu, Zhongchen; Jiang, Jie; Li, Na

2015-11-01

A low-temperature microplasma generated in a dielectric barrier discharge (DBD) was used as a radiation source for the excitation of hydrogen sulfide and its determination by molecular emission spectrometry (MES). The excitation/emission chamber was enclosed to eliminate spectral interference from ambient air. The spectral emission lines of hydrogen sulfide were clearly discriminated from the background spectrum, and the emission line at 365.06 nm was selected for parameter optimization and quantitative analysis. The S(2-) ions in aqueous samples were reacted with acid to generate hydrogen sulfide and then determined. The experimental parameters affecting the determination of hydrogen sulfide and S(2-) were optimized. The limits of detection were 1.4 mg m(-3) for H2S and 11.2 mg L(-1) for S(2-). The repeatability of the method was satisfactory, as the RSD values were 2.3% for H2S and 1.8% for S(2-). The enclosed DBD-MES system was demonstrated to be a useful tool for the determination of hydrogen sulfide in gas samples and S(2-) in aqueous samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Preliminary Investigation of a Dielectric Barrier Discharge Lamp in Open Air at Atmospheric Pressure

International Nuclear Information System (INIS)

Liu Feng; Wang Wei-Wei; Chang Xi-Jiang; Liang Rong-Qing

2011-01-01

A dielectric barrier discharge (DBD) lamp is investigated by using sinusoidal power with a 10 kHz frequency in open air at atmospheric pressure. With increasing applied voltages, the different discharge phenomena appear. At relatively low voltages, the discharge states are general stochastic filamentary discharges with weak light. However, at relatively high voltages, the walls of quartz tubes are heated sharply by plasma, and then the dazzling light is emitted very quickly to form the DBD Lamp, corresponding to the low maintaining voltage that is lower than the ignited voltage. The discharge state or mode of the DBD lamp that corresponds to the glow discharge is deduced according to the wave form of the circuit current, which is evidently different from the filamentary discharges. Under these conditions, the spectrum of the DBD lamp is continuous in the range 400–932 nm, which is scanned in the range 300–932 nm. It is also shown that there is another discharge state or mode that is different from the traditional filamentary discharges. Therefore, it is concluded that the discharge state or mode of the DBD lamp is a glow discharge. (physics of gases, plasmas, and electric discharges)

Electrical and optical characteristics of the radio frequency surface dielectric barrier discharge plasma actuation

International Nuclear Information System (INIS)

Wang Wei-Long; Song Hui-Min; Li Jun; Jia Min; Wu Yun; Jin Di

2016-01-01

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. (paper)

Dielectric coatings on metal substrates

International Nuclear Information System (INIS)

Glaros, S.S.; Baker, P.; Milam, D.

1976-01-01

Large aperture, beryllium substrate-based mirrors have been used to focus high intensity pulsed laser beams. Finished surfaces have high reflectivity, low wavefront distortion, and high laser damage thresholds. This paper describes the development of a series of metallic coatings, surface finishing techniques, and dielectric overcoatings to meet specified performance requirements. Beryllium substrates were coated with copper, diamond-machined to within 5 micro-inches to final contour, nickel plated, and abrasively figured to final contour. Bond strengths for several bonding processes are presented. Dielectric overcoatings were deposited on finished multimetallic substrates to increase both reflectivity and the damage thresholds. Coatings were deposited using both high and low temperature processes which induce varying stresses in the finished coating substrate system. Data are presented to show the evolution of wavefront distortion, reflectivity, and damage thresholds throughout the many steps involved in fabrication

Dielectric properties of calicum and barium-doped strontium titanate

Science.gov (United States)

Tung, Li-Chun

Dielectric properties of high quality polycrystalline Ca- and Ba-doped SrTiO3 perovskites are studied by means of dielectric constant, dielectric loss and ferroelectric hysteresis measurements. Low frequency dispersion of the dielectric constant is found to be very small and a simple relaxor model may not be able to explain its dielectric behavior. Relaxation modes are found in these samples, and they are all interpreted as thermally activated Bipolar re-orientation across energy barriers. In Sr1- xCaxTiO3 (x = 0--0.3), two modes are found associated with different relaxation processes, and the concentration dependence implies a competition between these processes. In Sr1-xBa xTiO3 (x = 0--0.25), relaxation modes are found to be related to the structural transitions, and the relaxation modes persist at low doping levels (x Barret formula is discussed and two of the well-accepted models, anharmonic oscillator model and transverse Ising model, are found to be equivalent. Both of the Ca and Ba systems can be understood qualitatively within the concept of transverse Ising model.

Yield of H2O2 in Gas-Liquid Phase with Pulsed DBD

Science.gov (United States)

Jiang, Song; Wen, Yiyong; Liu, Kefu

2014-01-01

Electric discharge in water can generate a large number of oxidants such as ozone, hydrogen peroxide and hydroxyl radicals. In this paper, a non-thermal plasma processing system was established by means of pulsed dielectric barrier discharge in gas-liquid phase. The electrodes of discharge reactor were staggered. The yield of H2O2 was enhanced after discharge. The effects of discharge time, discharge voltage, frequency, initial pH value, and feed gas were investigated. The concentration of hydrogen peroxide and ozone was measured after discharge. The experimental results were fully analyzed. The chemical reaction equations in water were given as much as possible. At last, the water containing Rhodamine B was tested in this system. The degradation rate came to 94.22% in 30 min.

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

Science.gov (United States)

Houba, Tomas

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

Time-dependent one-dimensional simulation of atmospheric dielectric barrier discharge in N2/O2/H2O using COMSOL Multiphysics

Science.gov (United States)

Sohbatzadeh, F.; Soltani, H.

2018-04-01

The results of time-dependent one-dimensional modelling of a dielectric barrier discharge (DBD) in a nitrogen-oxygen-water vapor mixture at atmospheric pressure are presented. The voltage-current characteristics curves and the production of active species are studied. The discharge is driven by a sinusoidal alternating high voltage-power supply at 30 kV with frequency of 27 kHz. The electrodes and the dielectric are assumed to be copper and quartz, respectively. The current discharge consists of an electrical breakdown that occurs in each half-period. A detailed description of the electron attachment and detachment processes, surface charge accumulation, charged species recombination, conversion of negative and positive ions, ion production and losses, excitations and dissociations of molecules are taken into account. Time-dependent one-dimensional electron density, electric field, electric potential, electron temperature, densities of reactive oxygen species (ROS) and reactive nitrogen species (RNS) such as: O, O-, O+, {O}2^{ - } , {O}2^{ + } , O3, {N}, {N}2^{ + } , N2s and {N}2^{ - } are simulated versus time across the gas gap. The results of this work could be used in plasma-based pollutant degradation devices.

Surface oxygenation of polypropylene using an air dielectric barrier discharge: the effect of different electrode-platen combinations

International Nuclear Information System (INIS)

Upadhyay, D.J.; Cui, N.-Y.; Anderson, C.A.; Brown, N.M.D.

2004-01-01

Polypropylene film has been modified in an air dielectric barrier discharge using two different electrode-platen configurations: stainless steel wire electrode-rubber platen or ceramic electrode-aluminium platen combinations. Modified films were characterised by static contact angle measurements, X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS) and Fourier transform infrared spectroscopy (ATR-FT-IR). Surface hydrophilic modification appears to be governed by the presence of low-molecular weight oxidised functionalities using XPS and SIMS techniques. Irrespective of the type of electrode-platen combination used to obtain the discharge, oxygenated functionalities of identical nature are formed on the polymer surface. However, the degree of oxidation obtained by the discharge using the wire electrodes with the rubber platen was considerably greater. Further increase in the observed hydrophilicity due to molecular rearrangement and development of stable oxygenated functionalities was evident after 1 month of post-processing analysis

Laser induced fluorescence in nanosecond repetitively pulsed discharges for CO2 conversion

Science.gov (United States)

Martini, L. M.; Gatti, N.; Dilecce, G.; Scotoni, M.; Tosi, P.

2018-01-01

A CO2 nanosecond repetitively pulsed discharge (NRP) is a harsh environment for laser induced fluorescence (LIF) diagnostics. The difficulties arise from it being a strongly collisional system in which the gas composition, pressure and temperature, have quick and strong variations. The relevant diagnostic problems are described and illustrated through the application of LIF to the measurement of the OH radical in three different discharge configurations, with gas mixtures containing CO2 + H2O. These range from a dielectric barrier NRP with He buffer gas, a less hostile case in which absolute OH density measurement is possible, to an NRP in CO2+H2O, where the full set of drawbacks is at work. In the last case, the OH density measurement is not possible with laser pulses and detector time resolution in the ns time scale. Nevertheless, it is shown that with a proper knowledge of the collisional rate constants involved in the LIF process, a collisional energy transfer-LIF methodology is still applicable to deduce the gas composition from the analysis of LIF spectra.

[Study on A White-Eye Pattern in Dielectric Barrier Discharge by Optical Emission Spectrum].

Science.gov (United States)

Zhu, Ping; Dong, Li-fang; Yang, Jing; Zhang, Yu; Zhang, Chao

2015-06-01

The white-eye pattern was firstly observed and investigated in a dielectric barrier discharge system in the mixture of argon and air whose content can be varied whenever necessary, and the study shows that the white-eye cell is an interleaving of three different hexagonal sub-structures: the center spot, the halo, and the ambient spots. The white-eye pattern is observed at a lower applied voltage. In this experiment, the heat capacity of water is high so that the water in water electrode is good at absorbing heat. In the process of pattern discharging the gas gap didn't increase its temperature, and the discharging phenomenon of this pattern has not changed. The temperature of the water electrodes almost keeps unchanged during the whole experiment, which is advantageous for the long-term stable measurement. Pictures recorded by ordinary camera with long exposure time in the same argon content condition show that the center spot, the halo, and the ambient spots og the white-eye pattern have different brightness, which may prove that their plasma states are different. And, it is worth noting that there are obvious differences of brightness not only on the center spot, the halo, and the ambient spots at the same pressure but also at the different pressure, which shows that its plasma state also changed with the variation of the pressure. Given this, in this experiment plasma temperatures of the central spot, halo, and ambient spots in a white-eye pattern at different gas pressure were studied by using optical emission spectra. The molecular vibration temperature is investigated by the emission spectra of nitrogen band of second positive system ( C3Πu --> B3Πg ). The electron excitation temperature is researched by the relative intensity ratio method of spectral lines of Ar I 763. 51 nm (2P6 --> 1S5) and Ar I 772. 42 nm (2P2 --> 1S3). The electronic density is investigated by the broadening of spectral line 696.5 nm. Through the analysis of experimental results, it

Time history of diesel particle deposition in cylindrical dielectric barrier discharge reactors

Energy Technology Data Exchange (ETDEWEB)

Talebizadeh, P.; Rahimzadeh, H., E-mail: rahimzad@aut.ac.ir [Amirkabir University of Technology, Department of Mechanical Engineering (Iran, Islamic Republic of); Ahmadi, G. [Clarkson University, Department of Mechanical and Aeronautical Engineering (United States); Brown, R. [Queensland University of Technology, Biofuel Engine Research Facility (Australia); Inthavong, K. [RMIT University, School of Aerospace, Mechanical and Manufacturing Engineering (Australia)

2016-12-15

Non-thermal plasma (NTP) treatment reactors have recently been developed for elimination of diesel particulate matter for reducing both the mass and number concentration of particles. The role of the plasma itself is obscured by the phenomenon of particle deposition on the reactor surface. Therefore, in this study, the Lagrangian particle transport model is used to simulate the dispersion and deposition of nano-particles in the range of 5 to 500 nm in a NTP reactor in the absence of an electric field. A conventional cylindrical dielectric barrier discharge reactor is selected for the analysis. Brownian diffusion, gravity and Saffman lift forces were included in the simulations, and the deposition efficiencies of different sized diesel particles were studied. The results show that for the studied particle diameters, the effect of Saffman lift is negligible and gravity only affects the motion of particles with a diameter of 500 nm or larger. Time histories of particle transport and deposition were evaluated for one-time injection and a continuous (multiple-time) injection. The results show that the number of deposited particles for one-time injection is identical to the number of deposited particles for multiple-time injections when adjusted with the shift in time. Furthermore, the maximum number of escaped particles occurs at 0.045 s after the injection for all particle diameters. The presented results show that some particle reduction previously ascribed to plasma treatment has ignored contributions from the surface deposition.

Time history of diesel particle deposition in cylindrical dielectric barrier discharge reactors

International Nuclear Information System (INIS)

Talebizadeh, P.; Rahimzadeh, H.; Ahmadi, G.; Brown, R.; Inthavong, K.

2016-01-01

Non-thermal plasma (NTP) treatment reactors have recently been developed for elimination of diesel particulate matter for reducing both the mass and number concentration of particles. The role of the plasma itself is obscured by the phenomenon of particle deposition on the reactor surface. Therefore, in this study, the Lagrangian particle transport model is used to simulate the dispersion and deposition of nano-particles in the range of 5 to 500 nm in a NTP reactor in the absence of an electric field. A conventional cylindrical dielectric barrier discharge reactor is selected for the analysis. Brownian diffusion, gravity and Saffman lift forces were included in the simulations, and the deposition efficiencies of different sized diesel particles were studied. The results show that for the studied particle diameters, the effect of Saffman lift is negligible and gravity only affects the motion of particles with a diameter of 500 nm or larger. Time histories of particle transport and deposition were evaluated for one-time injection and a continuous (multiple-time) injection. The results show that the number of deposited particles for one-time injection is identical to the number of deposited particles for multiple-time injections when adjusted with the shift in time. Furthermore, the maximum number of escaped particles occurs at 0.045 s after the injection for all particle diameters. The presented results show that some particle reduction previously ascribed to plasma treatment has ignored contributions from the surface deposition.

Studies on nitric oxide removal in simulated gas compositions under plasma-dielectric/catalytic discharges

International Nuclear Information System (INIS)

Rajanikanth, B.S.; Rout, Satyabrata

2001-01-01

Application of pulsed electrical discharges for gas cleaning is gaining prominence, mainly from the energy consideration point of view. This present paper presents recent work on applying the electrical discharge plasma technology for treating gaseous pollutants, in general, and nitric oxide, in particular, as this is one of the major contributors to air pollution. The present work focuses attention on pulsed electrical discharge technique for nitric oxide removal from simulated gas compositions and study of effect of packed dielectric pellets, with and without a coating of catalyst, on the removal process. Experiments were conducted in a cylindrical corona reactor energized by repetitive high voltage pulses. The effects of various parameters, viz. pulse voltage magnitude, pulse frequency, initial nitric oxide concentration and gas mixture composition on nitric oxide removal efficiency, are discussed. When the reactors were filled with different dielectric pellets like, barium titanate, alumina, and alumina coated with palladium catalyst, the improvement in nitric oxide removal efficiency is studied and discussed. The power dissipated in the reactor and the energy consumed per nitric oxide molecule removed was calculated. Further results and comparative study of various cases are presented in the paper

Numerical studies on soliton propagation in the dielectric media by the nonlinear Lorentz computational model

International Nuclear Information System (INIS)

Abe, H.; Okuda, H.

1994-06-01

Soliton propagation in the dielectric media has been simulated by using the nonlinear Lorentz computational model, which was recently developed to study the propagation of electromagnetic waves in a linear and a nonlinear dielectric. The model is constructed by combining a microscopic model used in the semi-classical approximation for dielectric media and the particle model developed for the plasma simulations. The carrier wave frequency is retained in the simulation so that not only the envelope of the soliton but also its phase can be followed in time. It is shown that the model may be useful for studying pulse propagation in the dielectric media

Low operating voltage InGaZnO thin-film transistors based on Al{sub 2}O{sub 3} high-k dielectrics fabricated using pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Geng, G. Z.; Liu, G. X.; Zhang, Q.; Shan, F. K. [Qingdao University, Qingdao (China); DongEui University, Busan (Korea, Republic of); Lee, W. J.; Shin, B. C. [DongEui University, Busan (Korea, Republic of); Cho, C. R. [Pusan National University, Busan (Korea, Republic of)

2014-05-15

Low-voltage-driven amorphous indium-gallium-zinc-oxide (IGZO) thin-film transistors (TFTs) with an Al{sub 2}O{sub 3} dielectric were fabricated on a Si substrate by using pulsed laser deposition. Both Al{sub 2}O{sub 3} and IGZO thin films are amorphous, and the thin films have very smooth surfaces. The Al{sub 2}O{sub 3} gate dielectric exhibits a very low leakage current density of 1.3 x 10{sup -8} A/cm{sup 2} at 5 V and a high capacitance density of 60.9 nF/cm{sup 2}. The IGZO TFT with a structure of Ni/IGZO/Al{sub 2}O{sub 3}/Si exhibits high performance with a low threshold voltage of 1.18 V, a high field effect mobility of 20.25 cm{sup 2}V{sup -1}s{sup -1}, an ultra small subthreshold swing of 87 mV/decade, and a high on/off current ratio of 3 x 10{sup 7}.

Cellulose triacetate, thin film dielectric capacitor

Science.gov (United States)

Yen, Shiao-Ping S. (Inventor); Jow, T. Richard (Inventor)

1995-01-01

Very thin films of cellulose triacetate are cast from a solution containing a small amount of high boiling temperature, non-solvent which evaporates last and lifts the film from the casting surface. Stretched, oriented, crystallized films have high electrical breakdown properties. Metallized films less than about 2 microns in thickness form self-healing electrodes for high energy density, pulsed power capacitors. Thicker films can be utilized as a dielectric for a capacitor.

Hydrostatic pressure effects on the dielectric response of potassium cyanide

International Nuclear Information System (INIS)

Ortiz Lopez, J.

1992-01-01

The complex dielectric constant of crystalline KCN was measured under hydrostatic pressures up to 6.1 kbar in the temperature and frequency ranges of 50-300 K and 10-10 5 Hz, respectively. It is found that the pressure derivative of the real part of the dielectric constant at all measured temperatures is negative. From these results we obtain estimates for the pressure and volume derivatives of polarizabilities. The anomaly in the real part of the dielectric constant at the elastic order-disorder transition shifts to higher temperatures with increasing pressure at a rate of 2.05 K/kbar. By carefully avoiding thermal cycling through this transition we find no evidence of the monoclinic phase reported to exist in the P-T phase diagram of KCN at relatively low pressures. Dielectric loss measurements show thermally-activated CN - reorientation rates in the elastically ordered phase with pressure-independent reorientational barriers and decreasing attempt frequencies for increasing pressures. Additional pressure effects on dielectric loss allow to obtain the pressure derivative of the antiferroelectric transition temperature as 1.97 K/kbar. (Author)

Improving Hydrophobicity of Glass Surface Using Dielectric Barrier Discharge Treatment in Atmospheric Air

International Nuclear Information System (INIS)

Fang Zhi; Qiu Yuchang; Wang Hui; Kuffel, E

2007-01-01

Non-thermal plasmas under atmospheric pressure are of great interest in industrial applications, especially in material surface treatment. In this paper, the treatment of a glass surface for improving hydrophobicity using the non-thermal plasma generated by dielectric barrier discharge (DBD) at atmospheric pressure in ambient air is conducted, and the surface properties of the glass before and after the DBD treatment are studied by using contact angle measurement, surface resistance measurement and wet flashover voltage tests. The effects of the applied voltage and time duration of DBD on the surface modification are studied, and the optimal conditions for the treatment are obtained. It is found that a layer of hydrophobic coating is formed on the glass surface after spraying a thin layer of silicone oil and undergoing the DBD treatment, and the improvement of hydrophobicity depends on DBD voltage and treating time. It seems that there exists an optimum treating time for a certain applied voltage of DBD during the surface treatment. The test results of thermal aging and chemical aging show that the hydrophobic layer has quite stable characteristics. The interaction mechanism between the DBD plasma and the glass surface is discussed. It is concluded that CH 3 and large molecule radicals can react with the radicals in the glass surface to replace OH, and the hydrophobicity of the glass surface is improved accordingly

Experimental study of surface dielectric barrier discharge in air and its ozone production

International Nuclear Information System (INIS)

Pekárek, Stanislav

2012-01-01

For surface dielectric barrier discharge in air we studied the effects of frequency of the driving voltage on dissipated power, asymmetry of amplitudes of the discharge voltage, discharge UV emission, ozone production, ozone production of the discharge with TiO 2 and of the discharge in magnetic field. We found that for a particular voltage the dissipated power is higher for the frequency of the driving voltage of 26.3 kHz than for the frequency of 10.9 kHz; peak values of the positive half-periods of the discharge voltage are higher than peak values of the negative half-periods; intensity of the discharge UV emissions for wavelengths of 320-420 nm is for both frequencies a linear function of power; maximum ozone concentration for the frequency of the driving voltage of 26.3 kHz is obtained with smaller power than for the frequency of 10.9 kHz; placement of TiO 2 particles into the discharge chamber increases for both frequencies of the driving voltage maximum ozone concentration produced by the discharge and for the frequency of the driving voltage of 26.3 kHz increases ozone production yield. Finally, there is no observable effect of magnetic field on concentration of ozone produced by the discharge as well as on production yield. (paper)

Formation of plasmon pulses in the cooperative decay of excitons of quantum dots near a metal surface

Energy Technology Data Exchange (ETDEWEB)

Shesterikov, A. B.; Gubin, M. Yu. [Vladimir State University (Russian Federation); Gladush, M. G. [Russian Academy of Sciences, Institute of Spectroscopy (Russian Federation); Prokhorov, A. V., E-mail: avprokhorov33@mail.ru [Vladimir State University (Russian Federation)

2017-01-15

The formation of pulses of surface electromagnetic waves at a metal–dielectric boundary is considered in the process of cooperative decay of excitons of quantum dots distributed near a metal surface in a dielectric layer. It is shown that the efficiency of exciton energy transfer to excited plasmons can, in principle, be increased by selecting the dielectric material with specified values of the complex permittivity. It is found that in the mean field approximation, the semiclassical model of formation of plasmon pulses in the system under study is reduced to the pendulum equation with the additional term of nonlinear losses.

The possibility of giant dielectric materials for multilayer ceramic capacitors.

Science.gov (United States)

Ishii, Tatsuya; Endo, Makoto; Masuda, Kenichiro; Ishida, Keisuke

2013-02-11

There have been numerous reports on discovery of giant dielectric permittivity materials called internal barrier layer capacitor in the recent years. We took particular note of one of such materials, i.e., BaTiO 3 with SiO 2 coating. It shows expressions of giant electric permittivity when processed by spark plasma sintering. So we evaluated various electrical characteristics of this material to find out whether it is applicable to multilayer ceramic capacitors. Our evaluation revealed that the isolated surface structure is the sole cause of expressions of giant dielectric permittivity.

Ambipolarity reduction in DMG asymmetric vacuum dielectric Schottky Barrier GAA MOSFET to improve hot carrier reliability

Science.gov (United States)

Kumar, Manoj; Haldar, Subhasis; Gupta, Mridula; Gupta, R. S.

2017-11-01

An explicit surface potential and subthreshold current model for novel Dual Metal Gate (DMG) Asymmetric Vacuum (AV) as gate dielectric Schottky Barrier (SB) Cylindrical Gate All Around (CGAA) MOSFET with the incorporation of localized charges (Nf) is developed to provide excellent immunity against threshold voltage (Vth) degradation due to hot carriers. Hot carrier induced Localized Charges (LC) either positive or negative leads to degrade the threshold of the device. The major advantage of the proposed DMG-AV-SB-CGAA MOSFET is that it mitigates the ambipolar behavior thus offering very good on current to off current ratio; and also reduces the electron temperature which leads to less hot carrier generation thus lesser degradation in Vth and improved Hot Carrier reliability. The surface potential is determined for three different regions by solving 1-D Poisson's and 2-D Laplace equation through separation of variable method to facilitate an optimal model for calculating the subthreshold drain current from Si-SiO2 interface boundary. The developed model results are in good agreement with that of ATLAS-TCAD simulation.

On the pulsating electric wind of a Single Dielectric Barrier Discharge (SDBD) plasma actuator

Science.gov (United States)

Vernet, Julie; Örlü, Ramis; Alfredsson, P. Henrik

2014-11-01

An experimental study is conducted on the electric wind produced by a Single Dielectric Barrier Discharge (SDBD) plasma actuator placed at the top of a half cylinder. Laser Doppler Velocimetry (LDV) measurements were performed and results show that increasing the driving voltage (6-16 kV peak-to-peak) and frequency (0.5-2 kHz) of the actuator increases the induced jet velocity (up to 4 m/s) and thus the momentum added by the actuator. The focus of the present study is on the phase-resolved behavior of the electric wind, in particular, its two strokes. Phase-averaged LDV data reveals that while the velocity during both strokes remains positive, there is nearly a factor of two in amplitude. The difference of behavior between the two strokes and its downstream and wall-normal evolution are mapped for various driving voltages. Results indicate that this difference is restricted to the vicinity of the actuator, thereby justifying the assumption of a steady force in simulations to model the induced force. The study is part of a larger investigation aiming at separation control on the A-pillar of a truck cabin. The support of the Swedish Energy Agency and SCANIA CV of the project Flow Research on Active and Novel Control Efficiency (FRANCE) is greatly acknowledged.

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

KAUST Repository

Zhang, Xuming

2013-09-23

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

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

Science.gov (United States)

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).

Surface treatment of aramid fiber by air dielectric barrier discharge plasma at atmospheric pressure

International Nuclear Information System (INIS)

Jia Caixia; Chen Ping; Liu Wei; Li Bin; Wang Qian

2011-01-01

Aramid fiber samples are treated by air dielectric barrier discharge (DBD) plasma at atmospheric pressure; the plasma treatment time is investigated as the major parameter. The effects of this treatment on the fiber surface physical and chemical properties are studied by using surface characterization techniques. Scanning electron microscopy (SEM) is performed to determine the surface morphology changes, X-ray photoelectron spectroscopy (XPS) is analyzed to reveal the surface chemical composition variations and dynamic contact angle analysis (DCAA) is used to examine the changes of the fiber surface wettability. In addition, the wetting behavior of a kind of thermoplastic resin, poly(phthalazinone ether sulfone ketone) (PPESK), on aramid fiber surface is also observed by SEM photos. The study shows that there seems to be an optimum treatment condition for surface modification of aramid fiber by the air DBD plasma. In this paper, after the 12 s, 27.6 W/cm 3 plasma treatment the aramid fiber surface roughness is significantly improved, some new oxygen-containing groups such as C-O, C=O and O=C-O are generated on the fiber surface and the fiber surface wettability is greatly enhanced, which results in the better wetting behavior of PPESK resin on the plasma-treated aramid fiber.

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

International Nuclear Information System (INIS)

Zhang, Xuming; Cha, Min Suk

2013-01-01

Dry reforming of methane has the potential to reduce the greenhouse gases methane and carbon dioxide and to generate hydrogen-rich syngas. In reforming methane, plasma-assisted reforming processes may have advantages over catalytic processes because they are free from coking and their response time for mobile applications is quick. Although plasma-assisted reforming techniques have seen recent developments, systematic studies that clarify the roles that electron-induced chemistry and thermo-chemistry play are needed for a full understanding of the mechanisms of plasma-assisted reformation. Here, we developed a temperature-controlled coaxial dielectric barrier discharge (DBD) apparatus to investigate the relative importance of electron-induced chemistry and thermo-chemistry in dry reforming of methane. In the tested background temperature range 297–773 K, electron-induced chemistry, as characterized by the physical properties of micro-discharges, was found to govern the conversions of CH 4 and CO 2 , while thermo-chemistry influenced the product selectivities because they were found to depend on the background temperature. Comparisons with results from arc-jet reformation indicated that thermo-chemistry is an efficient conversion method. Our findings may improve designs of plasma-assisted reformers by using relatively hotter plasma sources. However, detailed chemical kinetic studies are needed. (paper)

Supercoherent phenomena in pulsed power

International Nuclear Information System (INIS)

O'Rourke, R.C.

1983-01-01

This chapter proposes the formulation of programs of basic physics research to transform Pulsed Power Technology (PPT) to Pulsed Power Science and Technology (PPS and T) by formulating the laws of the quantized microscopic electromagnetic field; applying the microscopic electromagnetic field theory to the generation, propagation and deposition of pulses in nonlinear networks; learning more about the basic super coherent ''micro-structure'' in space and time of the many-photon states of pulsed laser beams; learning more about the basic super coherent ''micro-structure'' in space and time of the many-electronstates of pulsed electron and ion laser beams; and learning everything about the ''micro-picture'' of so-called ''dielectric breakdown'' and the associated absolute time delays. Promotes the idea that laser, electron and ion beams are similar kinds of pulses in the microscopic electromagnetic field. Presents expression for the microscopic electromagnetic field in order to show the role of supercoherence in PPS and T

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

Science.gov (United States)

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