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Studying ionic wind is crucial for deepening our comprehension of electrical discharge processes and refining their application in industrial technologies. This research investigates the behavior of needle–needle electrode using high-speed schlieren imaging techniques, focusing on the dynamics of ionic wind and its influence on spark discharge channel formation. Observations indicate that the ionic wind generated during corona discharge provides a structured pathway that significantly guides the development of spark discharge channels, particularly evident in horizontal configurations. Our findings reveal that the velocity and density of the ionic wind increase with decreasing curvature radius of the needle tip, thereby enhancing its guiding effect. Furthermore, the spark discharge channel forms through the convergence of positive and negative streamers, which meet near the cathode, leading to substantial disturbances in the surrounding flow field post-discharge. This research highlights the intricate relationship between corona and spark discharges, demonstrating the critical role of ionic wind in influencing discharge channel morphology and offering insights for future applications in plasma and electrostatic-based technologies. [ABSTRACT FROM AUTHOR]

Perfluoroisobutyronitrile (C4F7N) gas mixture is considered one of the most promising alternative gases for SF6 due to its excellent environmental protection and insulation performance. At present, the Shanghai region of China has adopted 8.5% C4F7N-86% CO2-5.5% O2 proportion gas mixture as the insulation medium for 126 kV gas insulated switchgear and has put it into practical engineering application. This paper conducted decomposition experiments on the proportion gas mixture under spark discharge, suspension discharge, and corona discharge conditions, respectively. The composition analysis of the decomposition products was carried out using a gas chromatography mass spectrometry and a gas chromatography-pulsed discharge helium ionization detector, which got decomposition products of the C4F7N/CO2/O2 gas mixture under discharge faults mainly include CO, CF4, C3F8, C4F8, C3F6, and CF3CN. According to the decomposition path of the C4F7N gas mixture, this paper selected three primary decomposition products (CO, CF4, C3F8) and one secondary decomposition product (C4F8) for the correlation characterization of discharge types, and proposed the ratios of c(CO)/c(CF4) and c(C4F8)/c(C3F8) as the characteristic quantities to characterize the different discharge types. Finally, in order to accurately identify the C4F7N/CO2/O2 gas mixture discharge type, this paper chose the decision tree algorithm to build a identification tree. The final identification result indicates that the ratio of c (CO)/c (CF4) and c (C4F8)/c (C3F8) can be used as the identification criterion for typical discharge fault types. [ABSTRACT FROM AUTHOR]

In this paper, an epoxy structural adhesive was fabricated by using the high‐performance thermoplastic engineering plastic phenolphthalein‐based polyaryletherketone (PEK‐C) as tougheners, and 4,4′‐diaminodiphenylsulfone (DDS) and 4,4‐diaminodiphenylmethane (DDM) as the curing agents. The effect of PEK‐C on the mechanical properties, microstructure, and adhesive properties of the modified epoxy resin system was investigated. Epoxy structural adhesive with 20 phr PEK‐C exhibited excellent bonding performance and thermal stability. The PEK‐C toughened adhesive presented high shear strength of 31.6 MPa and 27.6 MPa at 120°C and 150°C, respectively. The PEK‐C toughened epoxy structural adhesive was then used to bond CF/PEEK composites, and the effects on the bonding properties of CF/PEEK were investigated. By the combined treatment of sandpaper grinding and corona discharge (80 mesh sandpaper sanding + corona treatment for 30 s), the shear strength of the composite joints is increased to 18.73 MPa. And the shear strength retention rate of the joint was 99.8%. The strategy can be used to fabricate sandwich structures with CF/PEEK as the skin with excellent performance. Therefore, PEK‐C toughened modified epoxy resin is conducive to the enhancement of adhesive properties and has a better performance for the bonding of CF/PEEK materials. [ABSTRACT FROM AUTHOR]

An unprecedented thunderstorm ground enhancement (TGE) event was recorded on May 23, 2023, at Aragats Mountain, the highest peak in Armenia. This event showcased a maximum flux intensity surpassing 3 million particles per minute per square meter for energies above 0.4 MeV. Distinctly, the fluence of the event was measured at approximately ≈700 particles/cm2. The comprehensive instrumentation at the Aragats research station, including a suite of spectrometers and detectors, enabled precise cross-correlation of measurements. The electron flux at energies exceeding 10 MeV was observed at roughly ≈55,000 particles per minute per square meter. Additional measurements, including cloud base heights and corona discharge detections, validated the intensity of the electric field, reaching approximately 2.1 kV/cm at elevations 50–100 m above ground level. Our observations confirm that TGE is a universal and significant atmospheric event, contributing a substantial flux of high-energy electrons to the global electrical circuit. Integrating such TGE phenomena into Earth's numerical models is imperative, considering their impact on aviation and aerospace operation safety. [ABSTRACT FROM AUTHOR]

Fine particulate matter is challenging to capture due to its minuscule size, which affects its chargeability. The agglomeration method has been proven to be the most effective pretreatment technology for enhancing the removal of fine particles. This study proposes a novel dust-removal system that integrates turbulence-induced agglomeration into the wet electrostatic precipitator. The results showed that the removal efficiency of fine particles with a negative corona voltage was significantly higher, and removal efficiencies for particles smaller than 10.0 μm exceeded 90%. Furthermore, fine particles carried a larger charge when subjected to negative corona discharge, resulting in more-effective dust retention. The turbulence effect facilitates the removal of fine particles by promoting their agglomeration in turbulent conditions. The removal efficiency can increase significantly with turbulence, and this enhancement effect is more pronounced at higher flow rates. This study provides insight into the comprehensive removal of multiple pollutants from industrial flue gases. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the antimicrobial effect of direct cold atmospheric plasma (CAPP) treatment for pre-harvest application using four different crop species: Hordeum vulgare L. (barley), Triticum aestivum L. (wheat), Brassica napus L. (rapeseed) and Lupinus angustifolius L. (lupine). The model bacterium Bacillus atrophaeus served as a proxy for spore-forming plant pathogens on the seed surface. After semi-dry inoculation of spores onto the seeds, treatment with two different plasma sources, a volume-dielectric barrier discharge and a corona discharge, and different exposure times was carried out. Subsequently, recovery of viable spores from the seeds' surfaces was performed. Moreover, seed viability was determined based on maximum germination, as well as water contact angle as a measure for seed surface hydrophilicity. Direct CAPP treatment was efficient in reducing viable spores of B. atrophaeus with no significant differences between the plasma sources, reaching a mean inactivation of 1 log10 CFU/mL across all treatment times and crops species. Maximum germination of seeds was not negatively affected under any treatment condition. Seed hydrophilicity was increased for both plasma sources tested. Overall, this study provides valuable information on the efficiency of direct CAPP treatment of seeds with the purpose of seed hygienization with the premise of unaltered seed vitality and evaluates the potential application in comparison with previous investigated CAPP methods. [ABSTRACT FROM AUTHOR]

AbstractThe effects of corona-discharged atmospheric plasma treatment on the surfaces of polyvinyl chloride (PVC) were studied for their application in adhesively joining PVC with AA 6061 aluminium alloy. Although no alteration has been observed in the topography of the treated PVC surfaces, ATR-FTIR analysis reveals the incorporation of –OH functional groups. Therefore, the untreated hydrophobic surface of PVC changes to a hydrophilic nature after corona treatment. Single lap shear (SLS) specimens were prepared using treated PVC and Al bonded with a room temperature cure epoxy adhesive. The obtained SLS strength of the joint between 20-second treated PVC and etched Al is found to be 15 times larger than that of untreated PVC with as-received Al. [ABSTRACT FROM AUTHOR]

Direct fluorination has demonstrated efficacy in modulating the surface electrical properties of epoxy insulators and preventing surface charge accumulation. Comparative corona treatments were conducted on both surface fluorinated (modified) epoxy samples and untreated (virgin/original) samples using a modified electrode setup in a nitrogen (N2) atmosphere. The purpose was to evaluate the resistance of the modified epoxy surface layer against corona discharge. The results of ATR‐IR analysis and SEM surface and cross‐sectional imaging indicate that corona treatment did not alter the chemical composition of the fluorinated sample or the thickness of the fluorinated layer. Based on assessments of potential decay and water contact angle measurements, the surface conductivity of the modified sample was decreased by corona treatment. The wettability of fluorinated sample remained unchanged after corona treatment, and no soluble degradation products were produced. Conversely, the surface conductivity of the virgin sample exhibited an increase following corona treatment, accompanied by the formation of soluble degradation products. These results confirm that direct fluorination improves the epoxy insulator's discharge resistance in N2 and provides technical support for enhancing the electrical performance of epoxy insulators in gas insulated equipment. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Modern power industry widely uses high-voltage overhead lines to transport electrical energy, with these lines encountering the problems of corona discharge and leakage currents, especially under the conditions of rain and snowfall. One of the approaches to solving these problems is the creation of protective coatings that can diminish corona discharge under adverse weather conditions. This paper reports the results of studying a hydrophilic organosilicon coating based on aminopropyltriethoxysilane and poly(ethylene glycol) for aluminum wires. The study of the coating resistance to a long-term contact with water, UV radiation, and ozone-saturated atmosphere has shown that the hydrophilicity of the coating increases under the influence of these factors, thus improving its anticorona properties. Thus, the durability of the developed coating under the operating conditions opens prospects for its use in the power engineering. [ABSTRACT FROM AUTHOR]

Electrostatic precipitators (ESPs) have shown promise in reducing particulate matter (PM) emissions, but their potential for simultaneous NOx reduction in small-scale combustion systems remains underexplored. This study focuses on using non-thermal plasma generated in a corona discharge to reduce PM and NOx emissions from small-scale combustion. ESP was specifically designed for a commercially available 15 kW boiler with wood pellet combustion and used with both positive and negative discharge polarity to control emissions without any chemical additives. ESP performance was evaluated across a range of specific input energies (SIE) in terms of particle mass and number concentrations and NOx concentrations obtained by continuous gas analysis. ESP ensured the reduction in PM concentrations from 48 mg/m3 to the magnitude of PM content in the ambient air. The highest precipitation efficiency was observed for particles in the 20–200 nm range. Concurrently, NOx emissions were reduced by up to 78%, from 178 mg/m3 to 39 mg/m3. These results were achieved at specific input energies of 36 for positive and 48 J/L for negative corona, which is significantly lower than those reported for many existing separate PM and NOx control systems. This study demonstrates the potential of ESPs as a compact, energy-efficient solution for simultaneous PM and NOx removal in small-scale combustion systems, offering promising implications for improving air pollution control technologies for small-scale combustion systems. [ABSTRACT FROM AUTHOR]

The corona-generated electromagnetic field environment under and nearer to the extra high dc potential conductors generates an ill health environment which causes serious electrical threats to living organisms present in the conductor corridor. The ionized electromagnetic field environment is characterizing with ionized ionic current flow and enhanced electric field perturbation at ground levels. The primary factors which affect the safe and economical design dimensions of high potential dc conductors are conductor diameter, altitude, applied potential and atmospheric parameters such as temperature, humidity, pressure, and aerosol pollution, etc. This remains a challenging task to design the HVDC transmission system at extended potential levels, as HVDC system employed for a large amount of power transfer barrier in the electrical system to meet inevitable power thrust. To obtain a safe and economical design configuration, multiple experimental design measurements are essential at various climatic seasons which incorporates the tedious process and significant economical expenditure. To obtain the safe and cost-effective design dimension configuration, computational-based numerical analysis with final experimental validation offers substantial support. Using various computational methodologies, many researchers have attempted to guide the critical line design proportions to establish a safe and economical electrical environment beneath the lines at ground levels. All these computational techniques are emphasizing the algorithm iterative-based complex solutions claim the lack of computational accuracy. Hence, this work aims to provide a unique computational technique to analyse the ionised electromagnetic field environment of a unipolar UHV dc transmission system using modelling of the physics of the corona discharge procedure in the active high electrostatic field zone. Modelling of the corona discharge includes the estimation of the amount of new ionized ions generated in the ionization region dynamically claims complex less equations offer a unique solution. To validate the accuracy of the proposed computational technique, multiple outdoor experimental measurements are carried out at HV/EHV/UHV potential applications and discussed. Also, the computed results are compared with the experimental findings, from the comparison outstanding computational accuracy was marked. [ABSTRACT FROM AUTHOR]

Enhancing the corona resistance of epoxy resin (EP) is crucial for ensuring the reliable operation of electrical equipment and power systems, and the incorporation of inorganic nanofillers into epoxy resin has shown significant potential in achieving this. In this study, functionalized graphene oxide (KHGO) was synthesized via a sol-gel method to enhance the corona resistance of EP with electrochemical impedance spectroscopy (EIS) used to assess the properties of KHGO/EP composites. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) verified the successful grafting of epoxy groups onto the GO surface. The thermal conductivity and stability of the KHGO/EP composite initially increased with KHGO content but declined when the content exceeded 1.2 wt.%. Positron annihilation lifetime spectroscopy (PALS) indicated that KHGO improved interfacial compatibility with EP compared to GO, with agglomeration occurring when KHGO content exceeded a threshold value (1.2 wt.%). EIS analysis revealed that the corona resistance of the KHGO/EP composite was optimal at a filler content of 0.9 wt.%. After corona treatment, the saturation water uptake of the 0.9 wt.% KHGO/EP composite decreased by 15% compared to pure EP with its porosity reduced to just 1/40th of that of pure EP. This study underscores that well-dispersed KHGO/EP composite exhibits excellent corona resistance property suggesting the potential for industrial applications in high-voltage equipment insulation. [ABSTRACT FROM AUTHOR]

When an airplane flies in an electric field under a thundercloud, electric fields at the edges and projected portions of the airplane are enhanced and leaders emanate from there. When a positive leader emanating upward from the airplane connects with a downward negative leader from the bottom of an ordinary thundercloud and a negative leader emanating downward from the airplane connects with an upward positive leader from the ground, a large lightning current flows along the channel bridged between the thundercloud and the ground through the airplane. Recently, a method to reduce the risk of lightning strikes to airplanes has been proposed. It controls the charge on the surface of an airplane to suppress the electric field at edges and projected portions of the airplane. In this paper, an airplane under a thundercloud is represented with a vertical conducting bar or a horizontal conducting bar with a small projected portion, which is placed between impulse‐high‐voltage‐applied two flat electrodes, and it is analyzed using the finite‐difference time‐domain (FDTD) method. Corona and leader discharges emanating from edges and projected portions of an airplane model are considered with their engineering representations: 40‐μS/m and 0.02 S/m conducting regions for corona and leader discharges, respectively. The airplane model is not pre‐charged or pre‐charged negatively. It follows from the FDTD‐computed results that pre‐charging an airplane model with a relevant amount of negative charge can avoid discharges from and to the airplane model. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Plasma from electric discharges can be used in the abatement of volatile organic compounds (VOCs). The application of gas-phase pulsed corona discharge (PCD) in air–water mixtures provides favorable conditions for the oxidation of VOCs at unsurpassed energy efficiency. This research investigates the impact of water sprinkling on PCD performance in the oxidation of m-xylene as a model compound. Experimental research into the plasma treatment of continuous air flow was undertaken using the PCD reactor in dry and water-sprinkled modes. Water sprinkling more than doubled the m-xylene oxidation rate, which can be attributed to abundant OH-radicals produced at the plasma–water interface. Water sprinkling substantially reduced the formation of nitrous oxide, which is considered to be a secondary pollutant in the outlet air. Ozone is considered a by-product helping the subsequent photocatalytic oxidation of potential residues and photocatalyst maintenance. The use of water-sprinkled PCD is a promising approach to energy-efficient abatement of VOCs. [ABSTRACT FROM AUTHOR]

Four parameterizations, distinguishing between land and ocean, have been developed to simulate global distributions of thundercloud streamer corona discharges (also known as Blue LUminous Events or BLUEs) mainly producing bluish optical emissions associated with the second positive system of N 2 accompanied by no (or hardly detectable) 777.4 nm light emission. BLUEs occur globally about 12 times less frequently than lightning flashes. The four schemes are based on non-linear functions of the cloud-top height (CTH), the product of the convective available potential energy (CAPE) and total precipitation (TP), the product of CAPE and specific cloud liquid water content (CLWC), and the product of CAPE and specific cloud snow water content (CSWC). Considering that thunderstorms occur on hourly timescales, these parameterizations have been tested using hourly ERA5 data (except for CTH, not available in ERA5) for the meteorological variables considered, finding that the proposed BLUE schemes work fine and are consistent with observations by the Atmosphere–Space Interactions Monitor (ASIM). Moreover, the parameterizations have been implemented in a global chemistry–climate model that generates annual and seasonal global distributions for present-day and end of 21st century climate scenarios. Present-day predictions are in reasonable agreement with recent observations by the ASIM. Predictions for the end of the 21st century suggest BLUE occurrence rates that range between 13 % higher (∼ 3 % K -1) and 52 % higher (∼ 13 % K -1) than present-day average occurrences of BLUEs. [ABSTRACT FROM AUTHOR]

A computational study of the inception of positive wire-cylinder corona discharges in low-pressure air in crossed electric and magnetic fields is performed. The inception voltages are calculated for a wide range of gas densities, wire radii, and applied magnetic fields. Conditions are considered when the reduced electric fields at wire electrodes reach extremely high values of about 10 kTd. An expression applicable at such strong fields for the ionization coefficient, which is a key parameter of the corona inception model, is presented against the values of electric and magnetic fields. Calculated inception voltages agree with a large quantity of available experimental data on low-pressure positive corona discharges, obtained both with and without the application of magnetic fields. The calculation results describe specific details of the non-monotonous dependence of the inception voltages on the magnetic field values, similar to those obtained in experiments. [ABSTRACT FROM AUTHOR]

Ion mobility spectrometry (IMS) is a trace detection technique operating at atmospheric pressure. It is widely utilized in various fields, such as explosives and drug detection, chemical warfare agent detection, and biomedical applications, due to its fast response time and high sensitivity. The various of substances can be identified through analyzing the discrepancies in the drift time of charged particles in an electric field. Depending on the polarity of the charged particles, it can operate under either positive or negative ion mode. Currently, the majority of IMS operate in only one detection mode. For example, explosives detection operates under negative ion mode, while drug detection operates under positive ion mode. However, single detection mode system is prone to miss detections because some substances may differentially respond to positive and negative detection modes. Simultaneous detection under both positive and negative ion modes can further enhance detection accuracy. In this study, a dual-drift tube ion mobility spectrometry capable of simultaneously detecting positive and negative ions was constructed using corona discharge ionization source technology and a compact dual ion-gated pulse control circuit. The instrument parameters of IMS were optimized, while simultaneously determined hexogen, methamphetamine and the metabolite of trinitrotoluene (TNT), 2,4-diamino-6-nitrotoluene (2,4-DANT). The optimal experimental conditions were selected as follows: a drift gas flow rate of 600 mL/min, a carrier gas flow rate of 500 mL/min, a drift tube temperature of 100 ℃, and a thermal desorption temperature of 200 ℃. The reduced mobility values of 1.72 cm²/V·s and 1.44 cm²/V·s are obtained through the detection of explosive hexogen (RDX) and drug methamphetamine (MA), respectively. These values agree well with the reported values, thereby proving the reliability of the instrument’s detection. Finally, the performance of the developed instrument was evaluated using 2,4-DANT, this substance that can be detected under both positive and negative ion modes. Production peaks are observed in both modes, and the normalized mobility values for 2,4-DANT are reported as approximately 1.67 cm²/V·s and 1.33 cm²/V·s under positive and negative ion modes, respectively. Through exploring the detection limits for both positive and negative ions, it was revealed that the homemade dual ion mobility spectrometer is capable of simultaneous detection of both positive and negative ions, achieves the lowest detection limits of 200 pg and 260 pg for 2,4-DANT, respectively. Importantly, these detection limits are not significantly compromised by sample division, which underscores the broad applicability and value of the instrument, highlighting its potential in various fields. [ABSTRACT FROM AUTHOR]

Approaches to improving the electrode system of submersible electrohydropulse devices used for treating the bottom-hole zone of deep oil wells are analyzed with the purpose of increasing the oil flow rate at a hydrostatic pressure of up to 50 MPa and electric field strengths within the range of (0.5–1.5)∙107 V/m. The feasibility of increasing the voltage at the dielectric–liquid–metal interface up to Eign = 3∙107 V/m to ignite a discharge under high pressure conditions is demonstrated. The hysteresis of breakdown voltage in various liquids, such as an invert water-in-oil emulsion, formation water, and process water, is described and analyzed. Experiments are carried out at different values of hydrostatic pressure in the well. A possible mechanism for the appearance of hysteresis during repeated breakdowns of liquids during a decay and rise in operating voltage is explained. The necessity of taking the hysteresis effect into account when calculating the discharge ignition intensity in deep wells is shown. The efficiency of the impact of breakdown and corona discharges in water on the bottom-hole zone is compared. Options for using electrode systems with an increased electric field strength in the area of the pulse shaper in electrohydropulse devices for treating wells are shown. These include a dielectric patch with a small hole on the flat part of the working electrode. Types of plastic materials that could increase the level of electric field strength and carry out the required number of stable breakdown discharges for one hoisting operation, at least 4.0∙10 4 pulses, are described. [ABSTRACT FROM AUTHOR]

Orange juice is a highly nutritious beverage. Traditional pasteurization methods cause nutrient loss and taste changes. Plasma treatment (PT) is an emerging method with a high sterilization rate. This study investigated the effects of corona discharge plasma on the sterilization of orange juice by changes in color difference, total phenol content, and pH value. Single‐factor experiments revealed that higher voltage (40 kV) and longer sterilization time (25 min) had better sterilization effects. Response surface analysis indicated that frequency had the greatest impact on sterilization rates, and the optimal sterilization conditions were a voltage of 44.75 kV, a frequency of 9.46 kHz, and a sterilization time of 25 min. Under these conditions, the sterilization rate reached 97.9%, meeting the national standard of 104 colony‐forming units/mL (GB7101‐2022). Compared to untreated juices, the color difference value was 16.32, the pH value decreased by 0.12, and the total phenol content increased by 0.669 mg/mL. However, the evaporation of water plays an important role in increasing the total phenol co. Moreover, the comparative analysis showed that PT was comparable to pasteurization in terms of sterilization effects, flavor preservation, and the concentration of bioactive components. This study provides a theoretical basis for industrial applications of PT. [ABSTRACT FROM AUTHOR]

The microstructure and chemical properties of the corona discharge process could provide an effective method for predicting the performance of high-voltage cable insulation materials. In this work, the depth profile of the microstructure and chemical characteristics of corona discharge-treated PE were extensively investigated using Doppler broadening of position annihilation spectroscopy accompanied with positron annihilation lifetime spectroscopy, attenuated total reflectance Fourier transform infrared spectra, Raman spectra and contact angle measurement. By increasing corona discharge duration, the oxygen-containing polar groups, including hydroxyl, carbonyl and ester groups, strongly contribute to the deterioration of hydrophobicity and the enhancement of hydrophilicity. And the mean free volume size, with a broadening distribution, decreases slightly. The line shape S parameter decreases because of the decrease in free volume elements and the appearance of oxygen-containing groups. Also, the thickness of the degradation layer, determined from the S parameter with positron injection depth, increases and diffuses into the PE matrix. A linear S-W plot within the degradation layer of different corona treatment duration samples indicates the defect type does not change. The S parameter decreases and the W parameter increases with an increasing corona duration. Using a slow positron beam, the nondestructive probe can be used to profile the microstructure and chemical environment across the corona discharge damage depth, which is beneficial for investigating the surface and interfacial insulation materials. [ABSTRACT FROM AUTHOR]

Corona discharge is a significant problem in the operation of high-voltage transmission and distribution systems, particularly for polymer insulators. Numerical simulation has become an effective tool for investigating the underlying physical mechanisms and optimizing the design of insulators. In this paper, we present a two-dimensional numerical simulation study on corona discharge plasma affecting the surface behavior of polymer insulators. The simulation was performed with the Comsol Multiphysic software and is based on the finite element method and the fluid plasma model, which considers ionization, recombination, and the transport of plasma species. The numerical results are analyzed to study the spatial and temporal characteristics of the corona discharge and its effect on the surface behavior of polymer insulators. The results show that the electric field is affected not only by the volume charge density but also by the surface charge density, which in turn depends on the densities of the charge carriers migrating on the insulator surface. However, the electric field drops drastically when one or two grading rings are installed. But one grading ring is not enough to limit the discharge. [ABSTRACT FROM AUTHOR]

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Many countries worldwide are showing a growing interest in renewable energy sources, with wind energy being a particularly appealing option for generating mechanical energy. Researchers have explored different techniques for controlling the flow of air, including passive, active, and semi-active methods. In wind farms, the wake flow behind a turbine can be impacted by the flow from other turbines, and to address this issue, plasma-based corona discharge actuators are being considered as one of the most effective methods for reducing fluid flow separation on wind turbine blades. This study employs 2D and 3D numerical simulations to examine the use of corona discharge-based plasma actuators on the leading edge of tandem wind turbines within a wind farm. The study investigates how actuator voltage and frequency affect aerodynamic parameters such as lift, drag coefficients, and efficiency. The study incorporates the use of the Q-criterion to analyze vortex behavior and its interaction with the axial wind turbine body. Fluid flow modeling is conducted using the OPENFOAM software. The findings demonstrate that an escalation in both voltage and frequency of the corona discharge results in a decrease in the Q-criterion, attributed to the heightened ionic flow that diminishes the separation zone. Furthermore, reducing the distance between electrodes also aids in diminishing the Q-criterion values. Additionally, the study reveals that integrating corona plasma at the leading edge of wind turbine blades amplified power generation by more than 3.8%. The corona plasma actuator employed in the study had electrodes spaced 3 mm apart, operated at a voltage of 17 KV, and ran at a frequency of 13 kHz.

Before putting into operation, ultra-high voltage transformers need to undergo strict handover tests to ensure their safe and reliable operation. The grading capacity of the grading ring on the transformer will affect the accuracy of the handover test. When there are problems with high altitude environments or grading ring structures, their grading ability will change. It is particularly important to study and design grading rings that can have good grading ability in different situations. This article first uses COMSOL software to build a three-dimensional model of the withstand voltage test circuit of a 500 kV transformer. Secondly, the influence of changes in the pipe diameter and ring spacing of the equalizing ring on the equalizing capacity of the equalizing ring is studied. Finally, the variation of equalizing capacity of the equalizing ring in a rough state is studied. It is found that as the diameter of the equalizing pipe and the ring diameter increase or the distance between the rings decreases, the equalizing ability of the equalizing ring will be enhanced, with the greatest impact brought by the change in pipe diameter. When the grading ring has a rough surface, its grading ability will significantly decrease. Among them, the grading ability decreases most significantly when adhering to conical particles, and decreases least when concave, indicating that the smoother the surface of the grading ring, the better the grading ability. This study can provide some assistance for the design of grading rings for high altitude ultra-high voltage transformers.

This study investigates the paracetamol removal efficiency by multi-tip pulsed corona discharges, highlighting the conditions avoiding mutual effects between two consecutive streamer branching discharges generated by each tip. The results show that the production of reactive oxygen and nitrogen species (RONS) in the liquid phase and the efficiency of paracetamol removal are influenced by the distance between two contiguous tips due to the mutual effects for small inter-tip distances between 4 mm and 8 mm in the case of a fixed inter-electrode distance of 5 mm (i.e. distance between the tip summit and the water surface). Beyond an inter-tip distance of 12 mm (over twice the gap distance), the mutual effects of branching discharges were no longer observed since the field lines did not overlap, making the production and absorption of liquid-phase species more efficient. Furthermore, RONS production was almost linear when moving from one to four tip electrodes: [H2O2]1tip: 0.52 mg l–1 versus [H2O2]4tips: 1.99 mg l–1, a ratio of 3.82. Optimum values were reached for an inter-tip distance of 16 mm. In this case, the enhancement factor in this reactor configuration is the surface integration between the plasma and the liquid surface to be treated. Furthermore, the results show a quasi-exponential increase in the percentage of paracetamol degradation as a function of the number of electrodes, from 4% with a mono-tip configuration to over 78% for a treatment with a four tip one. [ABSTRACT FROM AUTHOR]

In this work a complete atmospheric electro–hydro-dynamic (EHD) thruster is tested in a subsonic wind tunnel, with the purpose of evaluating changes in performance due to simulated flight conditions and, for the first time, comparing them with a physical model of the drift region. An aerodynamic frame was designed to accommodate the electrodes inside the wind tunnel. Propulsive force and electrical measurements were conducted to assess performance exploiting dimensionless coefficients derived from one-dimensional theory. The results, on top of validating the theory, show how EHD thrusters can operate with a non-zero bulk velocity and highlight the importance of optimized frames and electrodes to enhance the capabilities of flying demonstrators. The test campaign revealed that the operating voltage envelope extends with increasing bulk velocity, leading to an increase in maximum thrust. [ABSTRACT FROM AUTHOR]

Ce doped MnO2/γ-Al2O3 catalysts are prepared and analysed by BET, XRD and SEM in this paper. The degradation of chlorobenzene (CB) by a synergistic system of catalyst and DC corona discharge is further investigated to examine the effects of discharge voltage on CB removal efficiency, CO2 selectivity and by-product O3 generation. The results show that the voltage is proportional to the removal efficiency of CB and the selectivity of CO2. At a voltage of 40 kV, the CB removal efficiency and CO2 selectivity are 88% and 75%, respectively. O3 is more likely to decompose into active oxygen atoms with Ce doped MnO2/γ-Al2O3 type catalyst, and its O3 emission is about 50–250 ppm lower than that of NTP alone. In addition to studying the effect of CB treatment, the decomposition mechanism of CB is also discussed by examining the exhaust gas by GC-MS. [ABSTRACT FROM AUTHOR]

In this paper, using a direct current (DC) corona discharge with a bee-slot wire-barrel construction, the degrading efficiency of non-methane hydrocarbons (NMHCs) was examined in terms of cooking temperature, duct gas flow rate, and discharge voltage. The amount of NMHCs produced was investigated under each condition of cooking temperature of 80–120 °C and cooking oils of soybean oil, peanut oil, canola oil and lard. When soybean oil was used as the cooking fume at a cooking temperature of 200 °C, the largest concentration of NMHCs was formed. In the degradation experiment, it was found that the corona discharge treatment effect was very good, which was proportional to the discharge voltage and inversely proportional to the cooking temperature and gas flow rate, and the treatment effect was the best when the discharge voltage was 34 kV, the cooking temperature was 120 ℃ and the gas flow rate was 25 m/s, the degradation rate reached 91.40%, and the degradation could meet the national emission standards. Meanwhile, the degradation mechanism of phenanthrene, anthracene and pyrene, which are more toxic and have larger concentration in the cooking fume, was analyzed. Furthermore, response surface optimization experiments were also conducted, and the best combination of the optimized factors was 34 kV input voltage, 127.7 °C cooking temperature, and 0.011 s treatment time.Highlights: The cooking fume was degradation by DC corona discharge. NMTH be studied about the impacts of various temperatures and oil types. Temperature, air velocity and discharge voltage were considered as influence factors. Response surface optimization experiments were also conducted. [ABSTRACT FROM AUTHOR]

Food packaging materials must be sterilized to prevent cross‐contamination of the product. Non‐thermal plasma (NTP) corona discharge can be an effective alternative sterilization method for packaging films. The inactivation efficiency atmospheric NTP corona discharge under dry and wet conditions against vegetative cells of Escherichia coli, Staphylococcus aureus and Bacillus subtilis, spores of B. subtilis and Clostridium sporogenes and fungal spores of Candida albicans, Penicillium expansum and Aspergillus niger on polymeric packaging films were studied. The maximum inactivation of these microorganisms was 5.58, 0.54, 1.51, 1.06, 2.47, 1.73, 2.80, 3.20 and 3.50 log, respectively. Microbial inactivation by the treatments was greatly enhanced under wet conditions. Gram‐negative bacteria were found to be more sensitive to NTP, but spores were more resistant than vegetative bacterial cells. Although fungi were less susceptible than bacteria in dry treatments, they became more sensitive than the Gram‐positive bacteria in wet treatments. Overall, plasma treatments under wet conditions achieved higher microbial inactivation and would be favourable over the dry treatment. [ABSTRACT FROM AUTHOR]

This paper presents a simulation approach to solve the steady-state corona model of a rod-type static discharger with a sharp tip. Based on the requirement of charge density distribution on the corona boundary, a novel iteration calculation method is proposed to automatically solve the corona zone range of the electrode boundary that cannot be predetermined for a sharp electrode. Moreover, a recursive calculation strategy that uses the corona convergence solution of some high-voltage parameters as the initial solution is employed to improve the computational stability and efficiency in scanning simulations with different voltage and wind speed parameters. Through the simulation and verification of a typical rod-type static discharger, we observed that the convergence is fast for the boundary range iteration, and the recursive calculation strategy is also effective. In addition, the volt–ampere characteristics and inception voltage obtained using the simulation were in good agreement with the measurement. Through simulation of a static discharger applied in a typical longitudinal wind field environment, we observed that the proposed approach is still effective at wind speeds up to hundreds of m/s. [ABSTRACT FROM AUTHOR]

Ion mobility spectrometry (IMS) is a trace detection technique operating at atmospheric pressure. It is widely utilized in various fields, such as explosives and drug detection, chemical warfare agent detection, and biomedical applications, due to its fast response time and high sensitivity. The various of substances can be identified through analyzing the discrepancies in the drift time of charged particles in an electric field. Depending on the polarity of the charged particles, it can operate under either positive or negative ion mode. Currently, the majority of IMS operate in only one detection mode. For example, explosives detection operates under negative ion mode, while drug detection operates under positive ion mode. However, single detection mode system is prone to miss detections because some substances may differentially respond to positive and negative detection modes. Simultaneous detection under both positive and negative ion modes can further enhance detection accuracy. In this study, a dual-drift tube ion mobility spectrometry capable of simultaneously detecting positive and negative ions was constructed using corona discharge ionization source technology and a compact dual ion-gated pulse control circuit. The instrument parameters of IMS were optimized, while simultaneously determined hexogen, methamphetamine and the metabolite of trinitrotoluene (TNT)，2,4-diamino-6-nitrotoluene (2,4-DANT). The optimal experimental conditions were selected as follows: a drift gas flow rate of 600 mL/min, a carrier gas flow rate of 500 mL/min, a drift tube temperature of 100 ℃, and a thermal desorption temperature of 200 ℃. The reduced mobility values of 1.72 cm2/V·s and 1.44 cm2/V·s are obtained through the detection of explosive hexogen (RDX) and drug methamphetamine (MA), respectively. These values agree well with the reported values, thereby proving the reliability of the instrument’s detection. Finally, the performance of the developed instrument was evaluated using 2,4-DANT, this substance that can be detected under both positive and negative ion modes. Production peaks are observed in both modes, and the normalized mobility values for 2,4-DANT are reported as approximately 1.67 cm2/V·s and 1.33 cm2/V·s under positive and negative ion modes, respectively. Through exploring the detection limits for both positive and negative ions, it was revealed that the homemade dual ion mobility spectrometer is capable of simultaneous detection of both positive and negative ions, achieves the lowest detection limits of 200 pg and 260 pg for 2,4-DANT, respectively. Importantly, these detection limits are not significantly compromised by sample division, which underscores the broad applicability and value of the instrument, highlighting its potential in various fields.

High voltage (HV) outdoor insulators are subjected to both electrical and environmental stresses, which may lead to their failure. Among the causes, corona discharge, humidity and UV radiation are considered to be the most damaging factors. Efforts are therefore underway to investigate new materials for improving the performance of insulating systems. In this research work, silicone-based room temperature vulcanized samples filled with alumina trihydrate (ATH), silicon dioxide and magnesium hydroxide (MH) were prepared and exposed to AC corona discharge for a duration of 110 h. The electric discharge was also accompanied by UV radiation and two different humidity levels. Following aging of the test samples, diagnosis was conducted to assess their integrity. Measurements based on determining the static contact angle demonstrated the loss of hydrophobicity of all the materials, while hydrophobicity recovery phenomena revealed that ATH-doped materials demonstrated a comparatively higher increase in the contact angle than in samples filled with silicone dioxide (silica) and MH. Scanning electron microscopy analysis revealed deep cracks and block-like structures on their surfaces. Similarly, energy-dispersive X-ray analysis indicated the signs of surface oxidation of the aged samples. However, the data of elemental composition exhibited the loss of filler contents as well as that of carbon from the base matrix. The overall assessment showed that resistance to suppress aging is influenced by both the filler type and its concentration in the investigated composites. The ATH-filled composites exhibited outstanding performance when exposed to the rigors of corona discharge and other environmental stresses. This research contributes to materials science and HV engineering by addressing the development of composites for enhanced insulator performance, with future aspects lying in the utilization of nano-composites for advanced functionality and durability.

Abstract The paper reports a low-cost handheld source of a cold air plasma intended for biomedical applications that can be made by anyone (detailed technical information and a step-by-step guide for creating the NTP source are provided). The plasma source employs a 1.4 W corona discharge in the needle-to-cone electrode configuration and is an extremely simple device, consisting basically of two electrodes and a cheap power supply. To achieve the best bactericidal effect, the plasma source has been optimized on Escherichia coli. The bactericidal ability of the plasma source was further tested on a wide range of microorganisms: Staphylococcus aureus as a representative of gram-positive bacteria, Pseudomonas aeruginosa as gram-negative bacteria, Candida albicans as yeasts, Trichophyton interdigitale as microfungi, and Deinococcus radiodurans as a representative of extremophilic bacteria resistant to many DNA-damaging agents, including ultraviolet and ionizing radiation. The testing showed that the plasma source inactivates all the microorganisms tested in several minutes (up to 105–107 CFU depending on a microorganism), proving its effectiveness against a wide spectrum of pathogens, in particular microfungi, yeasts, gram-positive and gram-negative bacteria. Studies of long-lived reactive species such as ozone, nitrogen oxides, hydrogen peroxide, nitrite, and nitrate revealed a strong correlation between ozone and the bactericidal effect, indicating that the bactericidal effect should generally be attributed to reactive oxygen species. This is the first comprehensive study of the bactericidal effect of a corona discharge in air and the formation of long-lived reactive species by the discharge, depending on both the interelectrode distance and the discharge current.

Blue corona discharges are often generated in thunderclouds penetrating into the stratosphere and are the optical manifestation of narrow bipolar events (NBEs) observed in radio signals. While their production appears to depend on convection, the cause and nature of such discharges are not well known. Here we show the observations by a lightning detection array of unusual amounts of 982 NBEs during a tropical storm on the coastline of China. NBEs of negative polarity are predominantly observed at the cloud top reaching the stratosphere, and positive NBEs are primarily at lower altitudes. We find that the dominant polarity changes with the typical time of development of thunderstorm cells, suggesting that the polarity depends on the phase of the storm cells. Furthermore, we find that the lightning jump of negative NBEs is associated with above-anvil cirrus plumes of ice crystals and water vapor in the lower stratosphere. We propose that variations in updrafts induce changes in the altitude and charge concentrations of the cloud layers, which lead to the polarity transition. Our results have implications for studies of the chemical perturbations of greenhouse gas concentrations by corona discharges at the tropopause. NBEs are intracloud lightning discharges with both positive and negative polarities. Here, the authors show that the dominant polarity of NBEs in the overshooting cloud depends on the phase of the storm cells. [ABSTRACT FROM AUTHOR]

Airborne pathogens, though a minor fraction of airborne particles, can cause infections, intoxications, or allergic reactions through respiration, dermal contact, or ingestion. The SARS-CoV-2 pandemic has underscored the significance of mitigating airborne microbial threats. Traditional air ionization methods, such as dielectric barrier discharge and metal tip corona discharge, produce ozone, a reactive and potentially harmful byproduct. However, carbon-fiber ionizers (CFIs) generate high concentrations of ions with minimal ozone production, making them a safer alternative. Operating at voltages below 5 kV, CFIs are more efficient than their metallic counterparts. This review focuses on the antimicrobial efficacy of CFIs, which produce unipolar ions that can disrupt microbial membranes, leading to cell death. Compared to ultraviolet light sterilization, CFIs are cost-effective and suitable for small spaces. The literature review highlights the need for comprehensive studies to evaluate the real-world application and effectiveness of CFIs. Many existing studies are limited by small-scale testing and insufficient data reporting, complicating comparative analyses. Our work aims to provide a detailed perspective on CFIs, examining their impact on various microorganisms, ion efficacy, ionization outcomes, and ozone generation levels. By addressing these aspects, the review seeks to offer an updated understanding of CFIs' antimicrobial capabilities and to identify limitations in current research, paving the way for more informed and effective air purification strategies. [ABSTRACT FROM AUTHOR]

This paper focuses on the combustion of hydrogen in boilers, as it appears to be a more effective method than using fuel cells for heating purposes due to higher boiler efficiency. One of the main disadvantages of hydrogen combustion in air is NO x formation. Therefore, the authors decided to introduce corona discharge as an innovative technique to clean hydrogen flue gas by effectively reducing NO x levels. The method involves generating positive plasma at atmospheric pressure by applying up to a 23 kV voltage difference between rod and ring-shaped electrodes. Experimental studies have shown that corona discharge can significantly lower the concentrations of NO and NO x in exhaust gases. The maximum DeNO x level was found to be 32.3%, while the plasma generator uses 17.5% of the power contained in burned hydrogen. The findings suggest that this technology holds potential for application in industrial hydrogen combustion systems, offering an environmentally friendly alternative to conventional NO x reduction methods. [Display omitted] • Corona discharge is promising approach for cleaning hydrogen flue gas from NO x. • The level of NO x removal depends on their concentration. • After plasma treatment, the level of NO decreases while NO 2 increases. • The maximum investigated level of DeNO x was 32.3%. [ABSTRACT FROM AUTHOR]

This work is devoted to the study of a negative corona discharge in air at atmospheric pressure. To ignite it, the edge (cathode) –plane (anode) system has been used with interelectrode gap of 10–20 mm long and edge curvature radius of ≈20 μm. For the first time, it has been established that in a certain voltage range, the Trichel pulse mode after ignition becomes unstable and is periodically replaced by the glow discharge mode with a current ≲ 1 μA. It is shown that at the stage preceding the first Trichel pulse, the discharge current is not recorded within measurement error of ±0.2 nA. [ABSTRACT FROM AUTHOR]

This paper presents a mathematical model derived from an equivalent electrical circuit to describe the dynamic behavior of the high-voltage terminal of a tandem Van de Graaff accelerator. Two approaches are presented for modeling the transit time of the current flowing through the corona needles. The first one considers an equivalent self-inductance in the corona triode, whereas, in the second one, the transit time is represented by a delay in the corona current. The validation of the proposed models was carried out through experimental tests developed at the National Nuclear Research Institute of Mexico. Furthermore, two strategies for controlling the slow variations of the terminal voltage limited by the slow response of the control loop based on corona discharge are evaluated: a Proportional–Integral–Derivative controller and a sliding mode controller. The Root-Mean-Squared Error calculation leads to the conclusion that both control strategies are suitable for regulating the voltage at the accelerator potential terminal. However, the sliding mode controller leads to an overshoot-free response and a shorter settling time. [ABSTRACT FROM AUTHOR]

The deformation of water droplets produced by melting icicles before and after electric discharge is studied through dynamic deformation experiments on an icicle–flat-plate electrode model. The maximum droplet deformation length, the critical growth rate of the deformation length, and the changes in droplet shape parameters at different applied voltages before and after the generation of discharge arcs are investigated. When no discharge occurs, the maximum droplet deformation length increases with increasing applied voltage, then decreases (primarily because of an opposing force exerted by the ionic wind generated by corona discharge), and then increases again. The critical growth rate of the droplet deformation length increases with increasing applied voltage. When discharge occurs, the maximum droplet deformation length exhibits a monotonically decreasing trend with increasing applied voltage, whereas the critical growth rate of the deformation length decreases, then increases, and then decreases again with increasing applied voltage. The falling pattern of droplets changes from a dripping faucet mode to a jet-like mode at sufficiently high applied voltage, and this is responsible for the sudden increase in the critical growth rate of droplet deformation. Both before and after discharge occurs, the shape parameter of the droplet shows an increasing trend with increasing applied voltage, and the evolution of droplet shape progresses from spherical to pear-like to bar-like. [ABSTRACT FROM AUTHOR]

This paper presents the results of an experimental investigation of the influence of electrode configuration on corona discharge and particle collection under ambient climatic conditions in Blade-to-Plane Electrostatic Precipitator (BP-ESP). In an experimental-scale electrostatic precipitator (BP-ESP), electrodes of different shapes (blade, saw blade with small tooth, and saw blade with large tooth) were tested. The experiments were performed with three types of dust particles having a mean size of about 5 µm, 10 µm, and 45 µm. An aerosol spectrometer was used to characterize the chemical composition of these dust particles injected into the ESP. Different DC-applied voltages have been taken into account for both positive and negative polarities. Results showed that a high current was generated with a saw blade electrode with large teeth which increased the particle collection efficiency, for both polarities. The negative corona discharge is overall more effective than the positive one for the different configurations of electrodes and dust particles used. [ABSTRACT FROM AUTHOR]

Under atmospheric pressure, partial discharge initiated by free metallic particles has consistently been a significant factor leading to failures in high-voltage electrical equipment. Simulating the propagation of negative streamer discharge in N2/O2 mixtures contributes to a better understanding of the occurrence and evolution of partial discharge, optimizing the insulation performance of electrical equipment. In this study, a two-dimensional plasma fluid dynamics model coupled with the current module was employed to simulate the evolution process of negative streamer discharge caused by one free metallic particle under a suspended potential at 220 kV applied voltage conditions. Simulation results indicated that the discharge process could be divided into two distinct stages: In the first stage, the electron ionization region detached from the electrode surface and propagated independently. During this stage, the corona discharge on the negative electrode surface provided seed electrons crucial for the subsequent development of negative corona discharge. The applied electric field played a dominant role in the propagation of the electron region, especially in the electron avalanche region. In the second stage, space charge gradually took over, causing distortion in the spatial field, particularly generating a substantial electric field gradient near the negative electrode surface, forming an ionization pattern dominated by ionization near the negative electrode surface. These simulation results contribute to a comprehensive understanding of the complex dynamic process of negative streamer discharge initiated by free metallic particles, providing essential insights for optimizing the design of electrical equipment and insulation systems. [ABSTRACT FROM AUTHOR]

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Micro-corona devices could be extensively utilized in gas sensing, switchgear, biomedicine, and other fields. As the influence mechanism of the cathode curvature radius on micro-corona discharge dynamical processes is very important for performance optimization and the promotion of these devices, a micro-scale corona discharge gas model in a mixture of N2-O2 is proposed based on the fluid–chemical mixing method, which describes the dynamic process of the discharge at atmosphere and normal temperatures. To reveal the influence mechanism of the nanowire curvature radius on the micro-corona discharge, the effect of the cathode nanowire radius on the discharge current, electric field, ionization reaction rate, and charged particle characteristics at different gaps and voltages were determined. The findings indicate that the effect of curvature radius on discharge intensity varies under different gap and voltage conditions. Further analysis indicates that an increase in curvature radius reduces the electric field near the tip while increasing the ionization area and secondary emission area as well as the number of positive ions in the space, consequently affecting the coupling process between the collision ionization and the secondary emission. Especially under the conditions of either small gap or low voltage, a suitable increase in the curvature radius could promote the coupling process and then increase the discharge current. [ABSTRACT FROM AUTHOR]

Triboelectric nanogenerator (TENG) operates on the principle of utilizing contact electrification and electrostatic induction. However, visualization and standardized quantification of surface charges for triboelectric materials remain challenging. Here, we report a surface charge visualization and standardized quantification method using electrostatic surface potential measured by Kevin probe and the iterative regularization strategy. Moreover, a tuning strategy on surface charge is demonstrated based on the corona discharge with a three-electrode design. The long-term stability and dissipation mechanisms of the injected negative or positive charges demonstrate high dependence on deep carrier traps in triboelectric materials. Typically, we achieved a 70-fold enhancement on the output voltage (~135.7 V) for the identical polytetrafluoroethylene (PTFE) based TENG (neg-PTFE/PTFE or posi-PTFE/PTFE triboelectric pair) with stable surface charge density (5% decay after 140 days). The charged PTFE was demonstrated as a robot e-skins for non-contact perception of object geometrics. This work provides valuable tools for surface charge visualization and quantification, giving a new strategy for a deeper understanding of contact electrification. A surface charge visualization and standardized quantification method and surface charge tuning is achieved for triboelectric materials, delivering essential tools for contact electrification and high-performance triboelectric nanogenerators. [ABSTRACT FROM AUTHOR]

The initiation of a positive corona discharge near a model hydrometeor in air is studied numerically. Hydrometeors in the form of an ellipsoid of revolution and a cylinder with two hemispheres at the ends are considered as models. Threshold characteristics (external electric field strength, particle charge) are obtained for hydrometers of various sizes and shapes at an atmospheric pressure of 0.4−1 atm. Analysis of the results of numerous calculation options shows that the threshold field strength at the top of the hydrometeor is determined by the curvature radius of the surface at this point and air pressure. A universal dependence of the reduced threshold field strength on the product of the curvature radius of the surface and air pressure is obtained. The simulation results indicate the possibility of initiating a corona discharge in a thundercloud from the top of a hydrometeor less than a centimeter long at a subthreshold reduced field strength of 10−15 kV∕(cm atm). [ABSTRACT FROM AUTHOR]

A low‐cost, high‐efficiency corona discharge detection method is important in ensuring the safety of high‐voltage transmission systems. High‐sensitivity solar‐blind deep‐ultraviolet (SBDU) photodetectors (PD) have obvious advantages in corona discharge detection. Herein, a fully transparent SBDU photoconductive detector with indium tin oxide (ITO) transparent electrodes is successfully constructed based on amorphous Ga2O3 (a‐Ga2O3) thin films. The device demonstrates an ultra‐high responsivity of 1.3 × 104 A W−1, a detectivity of 3.2 × 1014 Jones, and an external quantum efficiency of 6.7 × 106%. In addition, the capability of the ultra‐sensitive fully transparent photoconductive detector is investigated in terms of corona discharge detection. It is established that the device detection distance limit for simulated corona discharge detection is up to 70 cm, that is, the device can effectively detect extremely weak solar‐blind deep‐ultraviolet signals below 204 pW cm−2. A proof‐of‐concept for the future application of easily‐integrated fully transparent amorphous Ga2O3 photoconductive detectors with low manufacturing costs in high‐voltage corona discharge detection is provided. [ABSTRACT FROM AUTHOR]

In the present paper the polyelectrolyte multilayers (PEMs) deposited on lyophilized composite polylactic acid / poly(e-caprolactone) substrates were investigated. The substrates were charged under positive corona discharge for 1 min with 5 kV voltage applied to the corona electrode and 1 kV voltage of the same polarity applied to the grid. The dependences on the time of storage of the normalized surface potential of the charged substrates (positive) were investigated. Solutions of 1 % casein in phosphate buffer (pH 8) and 0.1 % chitosan in acetate buffer (pH 5) with added benzydamine hydrochloride were prepared. The creation of the multilayers was carried out by utilizing the technique Layer-by-Layer (LbL). The first built-up layer always possesses an electric charge opposite to that of the substrate. The loading efficiency and drug release kinetics of the chosen model drug were carried out spectrophotometrically. [ABSTRACT FROM AUTHOR]

Coal mine acid drainage is a type of industrial wastewater generated in the process of coal production and utilization that has a low pH and contains a small amount of organic matter and SO42−, which is harmful to the environment. The ·OH scavenger was used to optimize the grounded electrode atomized corona discharge (GEACD) technology for the treatment of coal mine acidic wastewater. The effects of various factors on the discharge effect were investigated, and the optimal operating scheme for the subsequent test was determined as 35 mm distance between barrel electrodes, 0.6 mm diameter of wire electrodes, and a flow rate of 45 mL/min. The effects of discharge voltage, discharge time, and ·OH scavenger on COD removal rate and pH in coal mine acid drainage were also investigated. The results showed that at the optimum discharge voltage of 12 kV, discharge time of 66 min, and SO42− to ethanol concentration ratio of 1, the COD value decreased from 152.84 mg/L to 43.27 mg/L, and the pH value increased from 5.6 to 6.1. [ABSTRACT FROM AUTHOR]

The reliability of GIS (gas-insulated switchgear) circuit breakers significantly depends on the condition of the insulated pull rods, with micro-defects on their surface posing a potential risk for micro-discharges and breakdown incidents. Experimentally investigating these micro-discharges is challenging due to their minute nature. This study introduces a framework to examine the linkage between micro-defects and micro-discharges, coupled with numerical simulations of the micro-discharge process in insulated pull rods afflicted by surface infiltration flaws under operational conditions. Initially, samples containing micro-defects were sectioned via water jet cutting for microstructural analysis through white light interferometry. Subsequently, a two-dimensional axisymmetric model simulating positive corona discharge from a needle to a plate electrode was employed to derive the relationship between charged particle density and the electric field in SF6 and air. Building on these observations, a micro-discharge model specific to micro-defects was developed. Comparative analysis of micro-discharge behaviors in SF6 and air for identical defect types was conducted. This research framework elucidates the discharge dynamics of charged particles in SF6 and air during micro-discharge events, shedding light on the mechanisms underpinning micro-discharges triggered by insulation rod defects. [ABSTRACT FROM AUTHOR]

One of the key challenges in Multi-Spectral Automatic Diagnostic (MAD) robot design is the precise targeting of narrow-angle cameras on a specific part of the equipment. The paper shows that a low-cost MAD robot, whose navigation system is based on open-source ArduRover firmware and a pair of low-cost Ublox F9P GNSS receivers, can inspect the 8 × 4 degree ultraviolet camera bounding the targeting error within 0.5 degrees. To achieve this result, we propose a new targeting procedure that can be implemented without any modifications in ArduRover firmware and outperforms more expensive solutions based on LiDAR SLAM and UWB. This paper will be interesting to the developers of robotic systems for power equipment inspection because it proposes a simple and effective solution for MAD robots' camera targeting and provides the first quantitative analysis of the GNSS reception conditions during power equipment inspection. This analysis is based on the experimental results collected during the inspection of the overhead power transmission lines and equipment inspections on the open switchgear of different power plants. Moreover, it includes not only satellite, dilution of precision, and positioning/heading estimation accuracy but also the direct measurements of angular errors that could be achieved on operating power plants using GNSS-only camera targeting. [ABSTRACT FROM AUTHOR]