Effect Of Corona Discharge Research Articles

Effect of corona discharge on the gas composition of the sample flow in a Gas Particle Partitioner

A Gas Particle Partitioner (GPP) that allows highly efficient separation of gas and particles with no effect on the thermodynamic conditions and substantially no change of the gas composition has been developed. The GPP is a coaxial arrangement with inner and outer electrodes and utilizes a corona discharge to electrically charge the particles and a strong electric field to remove them from the sample flow. Several measures were taken to avoid an influence of the corona discharge on the gas composition. The GPP can be applied for various applications. This paper focuses on the use of the GPP as a pre-filter for gas analyzers, where zero pressure drop and a minimization of the influence of the corona discharge on the gas composition are the main objective. Due to its design, the GPP introduces no changes to the thermodynamic conditions. However, corona discharge is known to produce significant amounts of ozone and oxides of nitrogen. The effect of the corona on the gas composition of the sample flow was determined under various conditions. The gas concentrations strongly depended on several aspects, such as material and diameter of the corona wire and polarity of the corona voltage. Due to the measures taken to minimize an effect on the gas composition, the concentrations of these gases could effectively be reduced. Along with the maximum gas-particle separation efficiency of near 100%, the additional O3 concentration was 42 ppbV and the additional NO2 concentration 15 ppbV. If an efficiency of 95% is acceptable, the added concentrations can be as low as 2.5 ppbV (O3) and 0.5 ppbV (NO2), respectively.

Influence of Space Charge on Upward Leader Initiation

Upward lightning is often observed on the coast of the Sea of Japan in winter season. Space charges by corona discharges at the grounded structures and on the ground or from the sea surface greatly affect the upward leader initiation, however, no studies of the effect of space charges have been carried out yet. In this paper, we calculate the electric fields around a conductor considering the effect of corona discharge from the conductor itself and on the ground using the DC ion flow calculation program that was developed by CRIEPI. Calculation results show that the upward leader initiation criteria are difficult to be satisfied for small conductors than large conductors because space charge reduces the electric field for the small conductors, and that space charge from conductors gives remarkable effects including polarity change on the ground level electric field in the downwind area.

Effects of corona charging of coating polymer powders on their minimum ignition energies

Abstract In the electrostatic powder coating systems, coating powders are highly charged by corona discharge in a spray gun. The charge amount is affected by supply voltage to the spray gun and feeding rate of coating powders. On the other hand, the minimum ignition energy (MIE) of coating powder is used for the evaluation of ignition hazards due to static electricity in the powder coating systems. The MIEs of coating powders charged by corona discharge were investigated experimentally using an ultrasonic vibrating-mesh MIE testing apparatus with a corona discharge unit for dust clouds. Coating powders of polyacrylonitrile (PAN), polymethylmethacrylate (PMMA), and Nylon 11 (PA) were used. It was confirmed from the experiment that corona charging decreased the MIEs for all the coating powders used in this study. This result was attributed to both changes in dispersion of coating powders due to corona charging and in discharge characteristics due to free ions produced by corona discharge. Therefore, the effect of corona discharge must be considered both in the MIE measurements of coating powders and in the risk assessment of ignition hazards in electrostatic powder coating systems.

Formation and structure of primary and secondary streamers in positive pulsed corona discharge—effect of oxygen concentration and applied voltage

Primary and secondary streamers of positive pulsed corona discharge are observed in a point-to-plane gap using a short-gated intensified CCD camera in an air-like environment. The influences of oxygen concentration and applied voltage on the properties of both streamers are presented. It is shown that the propagation velocity, the diameter, and the shape of the streamers are strongly influenced by the oxygen concentration. In pure nitrogen, the primary streamer shows branching with a diameter of about 0.2–0.4 mm, while in air, the branching disappears almost completely and the shape of the primary streamer becomes quite smooth with a diameter of more than 1 mm. After the arrival of the primary streamer at the cathode, a secondary streamer develops from the anode toward the cathode as far as the middle of the gap. The propagation length of the secondary streamer increases approximately linearly with the applied voltage. It is shown that the ratio of the energy consumed by the secondary streamer to the whole energy consumed by the discharge increases with the applied voltage.

H2 plasma for hydrogen loading in Pd

The preliminary results concerning the effect of negative corona discharge and that of a tensile uniaxial stress on the hydrogen solution in palladium are presented. By the simultaneous measurement on the same sample of its electrical resistance and dilatation it is inferred that both effects result in an increase of the hydrogen concentration in the hydride with respect to the unperturbed situation, i.e., equilibrium condition.

Computational modeling of charge dissipation of fabrics containing conductive fibers

Uncontrolled electrostatic discharges from charged personnel create a significant risk of hazards or product damage in the chemical and electronics industry. This paper deals with the theoretical modeling of the electrostatic properties of fabrics containing conductive fibers concentrating on the charge dissipation mechanisms involved. According to the simulations, the effect of corona discharge was shown to be surprisingly strong leading to extremely rapid neutralization of the charges on the fabric. However, some deviation from the theory may be expected in practice due to the unpredictable irregularities in the fine structure of fabrics and fibers. When the corona onset field was not exceeded, the charge decay was shown to mainly depend on the conductivity and dielectric properties of the base fabric, instead of the properties of the conductive yarns, provided they can be considered significantly more conductive than the base fabric. Without corona the geometric structure, especially the interval between the grounded conductive yarns, was only seen to change the effective surface potential observed, as assumed in the model, while the charge decay rate appeared to be practically unchanged.

Use of corona electret state in Bi-containing ferrite–garnet heterocompositions for thermomagnetic data recording

The effect of negative corona discharge on the magnetic properties and main technological parameters of 〈1 1 1〉 and 〈2 1 0〉 Bi-containing magnetic garnet films has been studied. Corona discharge treatment causes an enormous growth of the coercive force in the films. The mechanism of this effect has been discussed. A device has been developed for thermomagnetic information recording that uses the corona electret state in Bi-containing magnetic garnet films.

Synergistic effect of pulsed corona discharges and ozonation on decolourization of methylene blue in water

The effect of O2 and O3 bubbling on decolourization of methylene blue by pulsed corona discharges in water was studied. The pulsed corona discharges were produced by charging an 80 pF capacitor with a 40 kV DC source, through a 100 MΩ resistor, and discharging it into a needle-plate type reactor at 60 Hz through a rotating spark gap switch. A 20 ml sample of 13.25 mg l-1 methylene blue in distilled water was decolourized in 120 min. Bubbling O2 at 10 ml min-1 through the discharge region reduced the decolourization time to 25 min. Bubbling O2 containing 1500 µmol O3 l-1 at 10 ml min-1 reduced the decolourization time to 8 min. The O3 was produced by fractionating input energy between a water treatment reactor and a O3 generator, i.e. no additional energy was consumed for O3 production. Under the same experimental conditions methylene blue solution in tap water was decolourized in >210 min by corona discharge in solution, in 30 min by corona discharge with O2 bubbling, and in 11 min by corona discharge with bubbling of O2 containing 1500 µmol O3 l-1.

403 コロナ放電が予混合火炎伝ぱに与える影響 : コロナ放電発生状態の影響

In this study, the effect of corona discharge on the combustion phenomenon has been made clear. A homogeneous propane-air mixture was used and three equivalence ratios were tested. For generating the positive and negative corona discharge, a non-uniform electric field was applied to the combustion chamber by the needle to plane gap. One or five needle-shaped electrodes were used to change the corona discharge state. When the positive corona discharge was applied, the luminescence from corona with five-electrode was weak as compared with that of one-electrode. When the negative corona discharge was applied, the luminesence from corona and combustion were not affected by number of electrode. When the positive corona discharge was applied by low voltage, the combustion was improved in the case of one-electrode, but the index of combustion with one-electrode was almost equal to that of five-electrode when the high voltage was applied.

Improving allergen concentration homogeneity for investigating the effect of corona discharge on Der p1 allergen

Air ionisers utilising corona discharge have been commercially available for some time, although clinical trials have shown that these do not improve the health of asthma sufferers. New research has shown that the corona products can actually destroy allergens including the main allergen of the house dust mite Dermatophagoides pteronyssinus; Der p1. Concentration heterogeneity of commonly used sources of allergen and the additional problems that occur with electrostatic studies mean that present methods of allergen preparation are unsatisfactory. This paper describes work that improves the repeatability of tests investigating the effects of ionic bombardment on Der p1 allergen concentration. Initial experimental methods involved the distribution of sieved culture medium over a surface and divided into sectors for concentration analysis but this gave extremely variable data and so any effect of an allergen reduction method could not reliably be assessed. Different methods of distributing the sample are described in this paper. The results show that by dissolving Der p1 samples and using small evaporated aliquots, samples of homogenous concentration can be reliably used in electrostatic investigations. The benefits of using the new evaporated solution method is described with a comparison made between the effect of negative corona discharge on Der p1 using heterogeneous Der p1-containing culture particles and the new technique described in the present paper. Using the new technique of sample preparation, reductions in the Der p1 concentration increased from a significant ( P<0.01) 37.26% after 60 min to 67.37% after 300 min. Using faecal particles, however, led to insignificant ( P>0.05) reductions that ranged from 4.11% to 26.86% after 60 and 300 min, respectively.

Effect of Corona Discharge Treatment on the Dyeability of Low-Density Polyethylene Film

The effect of corona discharge on low-density polyethylene (LDPE) film was studied in terms of surface functionality and surface energetics of the film surfaces, improving the dyeability. The introduction of a polar group (O=C–O, C=O, and C–O) to a corona-treated LDPE film with acrylic acid could be confirmed by ESCA. The Owens–Wendt and Wu models using geometric means were studied to analyze the surface free energy of corona-treated film. It was found that the corona-treated LDPE film did lead to an increase in surface free energy, mainly due to the increase of its specific (or polar) component as the corona discharge power increased. Also, the K/S values were increased as the concentrations of dye increased. From the acid–base interaction point of view, it was found that the graft polymerization of acrylic acid onto the corona-treated LDPE film plays an important role in growing the acidic character which is one of the specific components of surface free energy, resulting in improving the dyeability with basic dyeing agent. A direct linear relationship is shown between the O1s/C1s ratio and the resulting K/S value or the specific component for this work.

Electrical and environmental stress and the hydrophobic stability of SIR, EVA and their blends

This paper treats the effects of electrical and environmental stresses on the hydrophobicity of polymers intended for use in nonceramic insulators. We investigated the effect of UV radiation, corona discharges, dry-band arcing, acid rain and water absorption on hydrophobic transfers in, and the aging of, room temperature vulcanized (RTV)-silicone rubber (SIR), high temperature vulcanized (HTV)-silicone rubber (SIR), ethylene vinyl acetate (EVA) rubber and the blends made from HTV-SIR and EVA. Acid rain had little influence on hydrophobicity in any of the samples. EVA and the blends with low silicone ratios to EVA allowed much larger reduction in hydrophobicity after or while subjected to the above stresses (except for acid rain) than did the silicone rubbers and a blend with a high silicone ratio to EVA. Salt-fog tests were conducted to correlate the hydrophobic stabilities of materials with leakage current levels thereon. The hydrophobic stability of the silicone rubbers was attributed to low-molecular-weight silicone components that were able to migrate and finally cover the aged surface layers. Because EVA possessed less fluid components and less chemical stability under electrical and environmental stresses, its hydrophobicity was readily reduced and hardly recovered, which led to higher current leakage and early material aging. For each material, the critical hydrophobic level permitting leakage current to develop was determined by adding a non-ionic wetting agent to saline water.

Corona Discharge Effects on Heat Transfer and Pressure Drop in Tube Flows

Corona Discharge Effects on Heat Transfer and Pressure Drop in Tube Flows

Biological Effects of Corona Discharge on Onions in a Commercial Storage Facility

The biological effect of corona discharge on onions (Allium cepa L.) in a commercial storage was investigated. Surface discoloration and mold were modestly but significantly reduced by the corona discharge when onions were stored for 2 or 4 weeks with or without an additional 2 weeks of shelf life under high humidity. Corona discharge treatment also reduced airborne mold spores in the storage room. No significant changes in internal decay, firmness, sprouting, or rooting, in treated onions were found.

Biological and Agricultural Studies on Application of Dischage Plasma and Electromagnetic Fields. Effects of Electric Fields, Air Ion and Corona Discharge on Plants.

This paper briefly reviews the effects of electric fields, air ions, and corona discharge on plants. From the middle of the eighteenth century, electric fields and air ions have been applied to plants both in the field and under laboratory conditions. Although many studies have reported beneficial effects, the results have been inconsistent, and the electrical conditions leading to definite benefits cannot so far be predicted. High electric fields have been reported to damage plants by flowing the induced currents caused by corona discharge from the tips. Since the investigations have been continued, the results have been controversial and contradictory. There remains no firm theory governing electrophysiology in plants.

Removal of NOx and SO2 from Air Excited by Streamer Corona: Experimental Results and Modeling

The effect of pulse corona discharge on NOx and SO2 concentrations in air has been studied. The initial concentrations and ammonia addition have been shown to influence the removal efficiency. An SO2 removal efficiency of 96% and an NO removal efficiency of 70% in pulse corona have been achieved with ammonia addition, for initial SO2 and NO concentrations of 480 ppm and 230 ppm, respectively. A numerical model for NO and SO2 conversion in homogeneous gas flow has been developed. The spatial nonuniformity of gas parameters associated with the existence of many streamer channels in a discharge chamber is taken into account. A comparison between experiments and modeling shows that SO2 removal is mainly determined by OH and O3-. NO conversion is achieved the reactions of O3, OH and N.

98/02269 Effect of a corona discharge on condensation of products of pyrolysis of wood and coal

98/02269 Effect of a corona discharge on condensation of products of pyrolysis of wood and coal

Dioxin and NOx Control Using Pilot-Scale Pulsed Corona PlasmaTechnology

We carried out tests on certain incinerator plant for two years from 1993 through 1994, to assure the effect of pulsed corona discharge for removal of NOx and dioxin in flue gas in the small-scale experimental apparatus. The gas volume of the test plant is 50NM3/H. By the experiment, high performance of dioxin removal at the gas temperature of 150°C was achieved. Regarding NOx, the reduction efficiency of NO was about 60 percents, whereas that of NOx including NO2 was 30 percents at most.

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Effects of corona discharge and high voltage on the growth of body mass and tumors in rats.

We investigated the increase in body mass and growth of tumors in rat exposed to negative and positive corona discharges (e-- and e+-ions) and high voltage electric fields (HVE) to determine any influence on body mass and tumor growth of electric fields, voltage, currents and electro magnetic fields. Tumor growth was evaluated by histological findings and analysis of the logistic curves (growth curve) determining the stabilized initial size of tumors (10cm3) corresponding to the synchronization of cultured cells. The histology of benzo (a) pyrene (BP)-stimulated tumor cells showed fibrosarcoma cells with abundant progressive pleomorphism and atypical cells in the control rats, and fibroblastic tumor cells with histiocytic and apoptotic cells with loss of pleomorphic and atypical cells in both e--ion and e+-ion and HVE groups. The logistic curves (growth curve) of tumor growth were represented by Hill's components, and reflected histological features. The tumor growth curve has two or three inflection points (x'') on the growth curve. Exposure of rats to both negative and positive corona discharges delayed tumor growth. While, body mass and tumor were activated by negative corona discharge (e--ion) and they grew 1.5 to 1.7-fold (body mass) and 1.2-fold (tumor) greater than in the respective control groups, finally. The effects of e--ion on growth may be via an induced chronic depolarizing response. Tumors in the e--ion group were cylindrical, extending toward the head, and these animals showed internal hemorrhaging after long term exposure. Rats exposed to the positive corona discharge (e+-ion) showed decreased body and tumor growth and survival. The circular tumors in the e+-ion group contained fibroblastic cells and a few apoptotic cells. These effects of e+-ion were thought to be due to a chronic hyperpolarizing response. Tumor growth under high voltage (HVE) showed a positive cooperative response (burst type cooperativity), which triggered at an early stage of tumor growth, and all internal organs merged mutually due to oppression by HVE. Therefore, the effects of electric fields, currents and high voltages, appear to be a stimulation of growth in the short term, but over the long term serious effects on health were seen.