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1.
Physical and chemical studies of corona discharges in air 总被引:1,自引:0,他引:1
This paper is devoted to a physical and chemical approach of DC coronas in air from a few Torr to 150 Torr. In the first part, the physical results obtained using a positive point-to-plane corona discharge are presented and described. In the second part, the ionic chemical species detected by mass spectrometry at the same conditions are introduced and commented. Finally, these results will be analysed in order to point-out correlations between the physical and chemical phenomena. 相似文献
2.
The ozone generation by negative corona discharge in coaxial cylindrical system of electrodes have been studied experimentally
in Ar+O2 and N2+O2 mixtures. Both in argon and nitrogen mixtures with oxygen the monotonous decrease in ozone concentration [O3] was observed at decreasing oxygen content in mixtures and the constant input energy density η. The rate coefficients for
the ozone generation and ozone decomposition were obtained by fitting experimentally measured data [O3]=f(η) with Vasiljev-Eremin formula. The calculated rate coefficient for ozone generation in N2+O2 mixtures at low content of oxygen (below 20%) was found considerably higher than that in Ar+O2 mixtures. Increase in the rate coefficients for ozone generation and decomposition was observed with decreasing content of
oxygen in both mixtures. The experimental results are in qualitative agreement with the simple model incorporating five main
chemical processes in mechanism of ozone generation.
The research was partially supported by Slovak Grant Agency under project 1/765920 The UK EPSRC (Grant GM/98944) and NATO
Joint Project PST CLG 976544. 相似文献
3.
Smulders E.H.W.M. van Heesch B.E.J.M. van Paasen S.S.V.B. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1998,26(5):1476-1484
Successful introduction of pulsed corona for industrial purposes very much depends on the reliability of high-voltage and pulsed power technology and on the efficiency of energy transfer. In addition, it is of the utmost importance that adequate electromagnetic compatibility (EMC) is achieved between the high-voltage pulse source and the surrounding equipment. Pulsed corona is generated in a pilot unit that produces narrow 50 MW pulses at 1000 pps (net average corona power 1.5 kW). The pilot unit can run continuously for use in industrial applications such as cleaning of gases (100 m3/h) containing NO or volatile organic compounds (VOCs) or fluids (e.g., waste water). Simultaneous removal of NO and ethylene to obtain clean CO2 from the exhaust of a combustion engine was tested at an industrial site. Various chemical processes, such as removal of toluene or styrene from an airflow are tested in the laboratory. We developed a model to analyze the conversion of these pollutants. To examine the discharges in the reactor we use current, voltage, and E-field sensors as well as a fast charge-coupled device (CCD) camera. Detailed energy input measurements are compared with CCD movies to investigate the efficiency of different streamer phases. EMC techniques incorporated in the pilot unit are based on the successful concept of constructing a low transfer impedance between common mode currents induced by pulsed power and differential mode voltages in signal lines and external main lines 相似文献
4.
T. Czech A. T. Sobczyk A. Jaworek 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,65(3):459-474
Results of spectroscopic investigations and current-voltage characteristics of corona
discharge and back discharge on fly-ash layer, generated in point-plane electrode geometry
in air at atmospheric pressure are presented in the paper. The characteristics of both
discharges are similar but differ in the current and voltage ranges of all the discharge
forms distinguished during the experiments. Three forms of back discharge, for positive
and negative polarity, were investigated: glow, streamer and low-current back-arc. In
order to characterize ionisation and excitation processes in back discharge, the emission
spectra were measured and compared with those obtained for normal corona discharge
generated in the same electrode configuration but with fly ash layer removed. The emission
spectra were measured in two discharge zones: near the tip of needle electrode and near
the plate. Visual forms of the discharge were recorded with digital camera and referred to
current-voltage characteristics and emission spectra. The measurements have shown that
spectral lines emitted by back discharge depend on the form of discharge and the discharge
current. From the comparison of the spectral lines of back and normal discharges an effect
of fly ash layer on the discharge morphology can be determined. The recorded emission
spectra formed by ionised gas and plasma near the needle electrode and fly ash layer are
different. It should be noted that in back arc emission, spectral lines of fly ash layer
components can be distinguished. On the other hand, in needle zone, the emission of high
intensity N2 second positive system and NO
γ
lines
can be noticed. Regardless of these gaseous lines, also atomic lines of dust layer were
present in the spectrum. The differences in spectra of back discharge for positive and
negative polarities of the needle electrode have been explained by considering the kind of
ions generated in the crater in fly ash layer. The aim of these studies is to better
understand the discharge processes encountered in electrostatic precipitators. 相似文献
5.
May Korachi Zi?an Turan Kenan ?entürk Fikrettin ?ahin Necdet Aslan 《Journal of Electrostatics》2009,67(4):678-685
A newly developed, low cost plasma system that works at atmospheric pressure and operates with both DC or AC high voltage power supplies was presented. This system was tested for its biocidal effect on a wide range of micro-organisms in water. Optimal killing parameters such as time, temperature and AC and DC high voltage power levels were tested for bacteria (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Streptococcus mutans, Bacillus subtilis), yeast (Candida albicans), fungi (Aspergillus niger) and green algae. Results show this system to have a very efficient biocidal effect on most bacteria, algae and fungi in water. 相似文献
6.
This paper presents the results of an investigation into the influence of corona formation processes at the tips of grounded rod electrodes on the probability of those rods being “struck” by high-voltage discharges. Experiments simulating the final stage of the attachment process were carried out with a composite voltage comprising a simultaneously applied impulse and DC potential of different levels to grounded rod electrodes simulating lightning rods, featuring either a spherical or pointed (conical) tip. The experiments show that corona does not influence the probability of the electrode being struck until a critical electric field (EF) strength is reached. 相似文献
7.
Ionic wind produced by an electro-aerodynamic pump based on corona and dielectric barrier discharges
The present study aims at showing the ability of ac discharges to be used as fanless blower in a rectangular channel. First, a 10 mm-high channel is used with four different types of ac atmospheric air discharges: an ac wire-to-plate corona discharge, two different ac wire-to-plate dielectric barrier discharges (DBD) and a surface DBD. The electrical and mechanical characteristics of the four different discharges are investigated and compared. They highlight that the best geometrical configuration is the wire-to-plate DBD with a thick dielectric, that allowed us to induce ionic wind velocity up to 3.3 m/s and flow rate per unit spanwise length of 24 L per second per meter. Secondly, this optimized configuration is reduced in size (2 mm-high channel) and the effect of this downscaling on the plasma actuator performances is studied, showing that the efficiency decreases with the channel height. 相似文献
8.
Using corona and glow discharges for improving strength properties and corrosion resistance of steel
V. F. Vorobyov A. S. Pomel’nikova M. N. Shipko M. A. Stepovich 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2011,5(6):1208-1211
The effect of glow and corona discharges on the strength and physicochemical properties of steels has been considered. It
has been found that the thickness of the hardened layer and the negative potential of the surface of the steel samples depend
on the current intensity and the time of treatment in a corona discharge. The variation of the surface potential correlated
with changes of the strength characteristics of steel. It has been shown that variation of the strength characteristics of
steel after its treatment in a corona discharge was connected with a rearrangement of the defect structure. The variation
of the strength characteristics of steel after its treatment in a glow discharge was due to implantation of nitrogen atoms
in surface layers of the material. 相似文献
9.
《Journal of Electrostatics》2006,64(7-9):569-573
Experimental and theoretical investigations have been conducted for the on-set of electrohydrodynamically (EHD) induced turbulence for cylinder in cross flow. The experiments were conducted for Reynolds numbers from 0.2 to 80 based on cylinder diameters, and Reynolds numbers from 103 to 4×103 based on the flow channel width. This flow conditions represent laminar to transitional-flow before the on-set of the EHD-turbulent flow. Theoretical analysis was based on the mass, momentum, and charged particle conservation equations coupled with the Poisson's equation for electric field evaluation. The results showed that: (1) on-set of EHD turbulence is initiated near the real-stagnation point; (2) EHD turbulence can be generated even for Reynolds numbers (Re) less than 0.2, if the EHD number (Ehd) is larger than the critical Reynolds number square (Ehd>Re2); and (3) the electrical origin of instability, which is leading into the on-set of turbulence can be estimated from Ehd/Db2>Re2 relation, where Db is the Debye number. 相似文献
10.
Based on a theoretical method of dimensional and similarity analysis and on published experimental data on the dynamics of
corona discharges in strong electrolytes, dimensionless numbers are found which make manifest the approximate similarity of
electrophysical and hydro/gasdynamic phenomena. A physical experiment is carried out, and generalized time dependences are
obtained for the current, voltage across the interelectrode gap, and plasma radius in terms of these similarity numbers.
Zh. Tekh. Fiz. 69, 30–34 (May 1999) 相似文献
11.
The assisted corona discharge is a unique discharge configuration that utilizes multiple collecting electrodes to minimize the voltage required to initiate a corona discharge and to generate an ionic wind. In this work, the geometric parameters that govern the formation of the assisted corona discharge and subsequent ionic wind are evaluated. Flow velocity measurements suggest that the geometry of the electrode spacings is optimized for ionic wind generation when the current flowing to the collector electrode is maximized, and that as the electrode gap is decreased to microscale dimensions, ionic wind production is inhibited. 相似文献
12.
In this paper, the effects of inlet air RH and air flow rate on positive and negative corona discharges in a corona-needle charger have been experimentally studied and discussed. Its corona discharge characterizations in terms of current-to-voltage relationships of the corona-needle charger on the effects of inlet air RH and air flow rate were evaluated at applied corona voltages between 0 and 3.1 kV, an air flow rates between 5 and 15 L/min, a relative humidity between 20 and 90%, and an operating pressure of about 101.3 kPa. Experimental results were shown that discharge current is strongly affected by the RH level of the inlet air. The positive discharge current was found to be decreased with increasing RH value at RH values below 60% and increased with increasing RH value at RH value above 60% in the same corona voltage. The negative discharge current was found to be stable with increasing RH value at RH values below 40% and increased with increasing RH value at RH value above 40% in the same corona voltage. For the air flow rate effects, the positive discharge current was found to slightly decrease when the air flow rate increased at RH value below 90% and to increase with the air flow rate at RH value of 90%. For the negative corona, the discharge current was also found to monotonically decrease when the air flow rate increased. 相似文献
13.
The properties of corona discharge in strong water electrolytes are studied experimentally. An analysis of the measured time-integrated spectrum of the corona plasma emission shows the presence of a thin vapor layer between the plasma and liquid. The time dependences of the layer thickness are derived from the discharge shadowgraphs. The role of the transition layer in the energy conversion process in a corona discharge in strong electrolytes is determined. 相似文献
14.
K. Sekimoto M. Takayama 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,60(3):589-599
The change in the distribution pattern of negative ions HO–, NOx-_{x}^{-} and COx-_{x}^{-} observed on arbitrary point-to-plane electrode configuration has been investigated by varying the angle of needle to the
plane electrode, under atmospheric pressure corona discharge
conditions. The stationary inhomogeneous electric field distributions between the point-to-plane electrodes with arbitrary
needle angle were calculated. The experimental and theoretical results obtained suggested that the negative ion evolutions
progress along field lines established between
the electrodes with arbitrary configurations and the resulting terminal ion formation on a given field line is attributable
to the electric field strength on the needle tip surface where the field line arose. The NOx-_{x}^{-} and COx-_{x}^{-} ions were dominantly produced on the field lines arising from the needle tip apex region with the highest electric field
strength, while the field lines emanating from the tip peripheral regions with lower field strength resulted in the formation
of the HO– ion. 相似文献
15.
《Journal of Electrostatics》2002,54(2):159-165
Current–voltage characteristics of a wire-and-tube electrostatic precipitator were measured under conditions of corona quenching. It was found that corona quenching is associated with an increase or decrease of the corona onset voltage (depending on the discharge electrode diameter) and with a strong deformation of the current–voltage characteristic for voltages close to the corona onset voltage. The current state of knowledge, describing corona quenching as a simple shift of the current–voltage characteristic to higher voltages, apparently goes back to measurements of less resolution. Possible mechanisms leading to an understanding of the newly observed phenomena are discussed. 相似文献
16.
17.
18.
S. Pekárek 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,61(3):657-662
The processes of ozone generation in non-thermal plasma produced by an
electrical discharge in air at atmospheric pressure are burdened by the
presence of nitrogen oxides, which on the one hand contribute to ozone
generation and on the other hand are responsible for unpleasant discharge
poisoning. The term discharge poisoning refers to the situation when the
discharge ozone formation completely breaks down. Discharge poisoning can be
affected by placing a catalyst in the discharge chamber. For the dc hollow
needle to mesh corona discharge enhanced by the flow of air through the
needle electrode we studied the effect of titanium dioxide TiO2, ZSM-5
zeolite or Cu++ZSM-5 zeolite on discharge poisoning by monitoring the
ozone, nitrogen monoxide and nitrogen dioxide discharge production. We found
that placing globules of any of these catalysts on the mesh decreases the
energy density of the onset of discharge poisoning, and this energy density
is smallest for a discharge with globules of a TiO2 on the mesh. 相似文献
19.
S. Koutchmy M. M. Molodenskii L. I. Starkova V. A. Kutvitskii A. V. Ershov 《Radiophysics and Quantum Electronics》1996,39(11-12):921-926
We present the results of observations of the white-light corona in polarized light (Criciuma, Brazil) in 1994. The space location of the surface Br=0 is calculated using the synoptic map of filaments during the solar eclipse. A good agreement was found between the corona ray structure and the surface folds and pleats, which result from its projection onto the sky plane. The measured polarization degree is compared with calculations by the Van de Hulst model. A conclusion is made concerning the adequacy between the proposed model and the observation data. 相似文献
20.
针-板系统电晕辐射场仿真实验 总被引:1,自引:1,他引:0
利用基于矩量法的电磁场仿真软件FEKO 5.1对针-板电极系统高压电晕辐射场的方向特征进行了计算机仿真,得出了不同形式的电晕放电的频谱范围. 相似文献