Corona Discharge Research Articles

Simulation study of the effect of electrode polarity on microscale corona discharge characteristics

Abstract The occurrence and application scenarios of micro-scale corona discharge are diverse, and the effect of micro-scale corona discharge mechanism and needle electrode polarity on corona discharge characteristics is still unclear. This paper establishes a microscale simulation model of pin-plate DC positive and negative corona fluid chemical reactions. The phenomenon of positive and negative corona discharge is being investigated. The internal discharge mechanism is analyzed from the microscopic point of view. Results demonstrate that positive corona discharge generates space charges that reduce the electric field strength between the needle electrode and amplify it between the plate electrodes. In contrast, negative corona discharge exhibits the opposite effect. The number of charged particles produced by microscale negative corona discharge is larger than that produced by positive corona, and the discharge phenomenon is more intense than that of positive corona. Under the simulation conditions in this paper, the ionization reaction rate of micro-scale positive and negative corona rises rapidly at the initial discharge. It will gradually remain stable after experiencing an upward pulse. The pulse peak value generated by micro-scale negative corona discharge is much higher than that of positive corona, and the pulse width of negative corona discharge is about half smaller than that of positive corona, which can reach a stable corona discharge state faster.

Research on characteristics of radio interference of MMC-HVDC lines

Abstract Previous research on radio interference in DC lines has focused on radio interference caused by corona discharge. But with the development of Modular Multilevel Converter Based High Voltage Direct Current (MMC-HVDC) systems, high frequency signals generated by fast switching of Insulate-Gate Bipolar Transistor (IGBT) are transmitted to Direct Current (DC) lines and radiate radio interference outward. On the one hand, the radio interference formula recommended by the dual-level DC transmission line recommended by International Special Committee on Radio Interference (CISPR) is calculated by the radio interference generated by the line corona discharge; On the other hand, by establishing a MMC-HVDC line model, analyse the high frequency signal transmission generated by the fast switching of IGBT in the Modular Multilevel Converter (MMC) to the radio interference generated by radiating outside the DC line. The results of the study show that the radio interference generated by high -frequency signals of IGBT fast switching will decrease with the length of the line. The radio interference value generated by corona discharge is 47.43 dB(μV/m), the radio interference generated by the high-frequency signal of IGBT fast switching is 40.83 dB(μV/m), which is too small than the radio interference of corona discharge.

Design and research of high-frequency electromagnetic wave detection antenna for discharge of transmission lines

Abstract Overhead lines have a wide range of applications in power systems. When early insulation faults occur in the long-term operation of overhead lines, corona discharge may occur. Timely detection of corona discharge can guide maintenance personnel to discover and eliminate faults in a timely manner. The height and distribution of overhead lines are relatively high, and close-range detection cannot quickly locate the discharge area. Using radio frequency antennas to measure the electromagnetic wave signals generated by corona discharge can achieve long-distance positioning detection of corona discharge. This article uses a log-periodic antenna as the detection antenna and simulates the antenna structure to prove that its directionality, gain, and measurement frequency band meet the design requirements. Finally, the discharge detection performance of the antenna is verified through experiments.

Conic Cross-Sectional Electrodes and Their Influence on Negative Corona Discharge and Trichel Pulse Characteristics

Conic Cross-Sectional Electrodes and Their Influence on Negative Corona Discharge and Trichel Pulse Characteristics

Three-terminal high-output triboelectric nanogenerator to achieve alternating current/direct current collaborative output by coupling three-dimensional porous structure, triboelectrification and corona discharge

Nowadays, the comprehensive consideration of output performance, durability, and industrial environmental recycling has been the focus of triboelectric nanogenerator (TENG) research in recent years. Herein, the melamine formaldehyde (MF) foam with the feature of three-dimensional porous structure, soft contact and eco-friendly is used to design a novel three-terminal high-output TENG (TH-TENG) to efficiently harvest rotating mechanical energy based on the coupling of electrostatic induction, triboelectrification and corona discharge. The simplified sliding TENG model has been demonstrated to have excellent electrical output of 532.81 μA m−2, with the outstanding resistance to heat and humidity of the output for maintaining 95.1 % and 82.1 % under the condition of 40 ℃ and 60 % RH, 20 ℃ and 80 % RH after 100 k cycles, respectively. Furthermore, the TH-TENG achieves efficient collaborative output of DC and AC through persistent directional movement and reciprocating movement with alternant connection of electrodes, where the upper-sided and lower-sided TENGs achieve DC with power density of 3.54 and 4.97 W m−3 Hz−1, and middle-sided TENG achieves AC with power density of 0.66 W m−3 Hz−1, respectively. The TH-TENG can drive 2540 LEDs and 8 incandescent lamps, and continuously power 36 hygrothermographs in parallel for smart farm. This work has enriched charge density enhancement strategy through the industrial recyclable MF foam.

Ranking factors affecting the decontamination efficacy of non-thermal plasma: The approach of dissipated power per plasma volume through machine learning modeling

Non-thermal plasma treatment can preserve food, but a meta-analysis assessing its efficacy has not been performed. This study retrieved the inactivation kinetics parameter log10D (n = 519), which varied largely among different plasma setups. Atmospheric pressure plasma jet, corona discharge, surface barrier discharge, dielectric barrier discharge, and inductively-coupled plasma had the highest efficacy with median D-values under 2 min. Dielectric barrier discharge, the most frequent setup (n = 160), was analyzed using dissipated power per plasma volume (W/cm3) as an integrated predictor of decontamination efficacy. Using conventional and machine learning approaches the most correlated parameters to the log10D were: dissipated power per plasma volume and matrix category, followed by microbial genus and pH. This study uses active learning to improve literature screening for data collection and various data analysis techniques for data treatment and ranking of the factors affecting non-thermal plasma decontamination. Industrial relevanceNon-thermal plasma decontamination shows potential but is also highly affected by the setup, and technical, biological, and food parameters. This study gives an overview of the decontamination performance that is to be expected for different matrix categories and setups, which could guide possible industrial applications. The ranking of the most important parameters to affect decontamination efficacy could be used for the optimization of these applications.

Hybrid dual-mode high-output triboelectric nanogenerator for achieving alternating current/direct current collaborative output

The large-scale practical application of triboelectric nanogenerators (TENGs) mainly depends on the limitations of output performance. On the basis of previous theory, this paper proposes a comprehensive strategy on the coupling of triboelectrification, corona discharge, volume effect, and space volume utilization of charge capture to enhance TENGs’ output. Thereby, a hybrid dual-mode high-output TENG (HDH-TENG) is proposed to efficiently harvest natural mechanical energy through a rotation-driven sliding-TENG (RS-TENG) and a magnetic-driven contact-separation TENG (MC-TENG). The simplified sliding-TENG with the combination of PU foam and vertical-radial electrodes achieves AC/DC collaborative output with charge density of 173.3 and 175.2 µC m−2, respectively. The simplified contact-separation TENG with the PU foam achieves AC output with charge density of 108.8 µC m−2. Furthermore, the integrated RS-TENG and MC-TENG achieve efficient collaborative output of DC with power density of 6.4 W m−2 Hz−1 and AC with power density of 128.6 mW m−2 Hz−1 through persistent directional sliding and contact separation, respectively, where a record-high constant current density output reached 1.9 mA m−2 Hz−1. The HDH-TENG can drive 6575 LEDs and 12 incandescent lamps, and continuously and stably power 52 hygrothermographs. This work further provides a new strategy for charge density enhancement of TENGs.

Innovative plasma treatment of orange juice to improve bioactive concentration: The effects of various parameters using response surface analysis.

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 (40kV) and longer sterilization time (25min) 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 44.75kV, a frequency of 9.46kHz, and a sterilization time of 25min. 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 0.669mg/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.

A novel application of artificial intelligence technology for outdoor high-voltage composite insulator

The distribution of the electric field plays a crucial role in evaluating the effectiveness of composite insulators. This research presents an innovative approach for optimizing the design of corona rings, aiming to decrease the electric field intensity in critical areas to satisfactory levels. The investigation examined the correlation among corona ring design variables and the intensity of the electric field close to the energized-end fitting in a 220 kV composite insulator equipped with a corona ring. Using design of experiment methods, the impact of three corona ring design parameters – corona ring diameter (R), ring tube diameter (Dr), and corona ring height (H) – was assessed. A novel nonlinear mathematical objective function was formulated, connecting the electric field magnitude to the structural parameters of the corona ring. Subsequently, the Bat algorithm, a bio-inspired optimization technique, was employed to enhance the initial corona ring design and mitigate the electric field intensity. Finally, the Finite Element Method (FEM) was utilized to simulate and evaluate the voltage distribution and electric field stress. The optimization process resulted in a substantial decrease in the highest electric field magnitude, by 58.6 % compared to the insulator with the threshold value, and 75 % when devoid of a corona ring. Additionally, the research highlighted the significant influence of ring tube thickness on the distribution of the electric field. The combination of experimental design and the Bat algorithm proved to be a powerful tool for optimizing the design of corona rings on transmission line composite insulators, providing precise solutions for optimizing corona discharge problems and enhancing the reliability of power transmission systems.

Study on the treatment of oil production wastewater by corona discharge coupling Fenton reagent

As the main by-product of oil production, oil production wastewater has the characteristics of high organic content and poor biodegradability, which makes the low temperature plasma wastewater treatment technology get new development. The Ground electrode atomization negative corona discharge（GEANCD） technology increases the discharge current on the basis of traditional corona discharge, but the uneven atomization of liquid is a key challenge at present, which will have a great impact on the degradation of wastewater pollutants. In this study, the GEANCD reactor was redesigned and a self-developed spiral wire hole electrode (SWHE) was used to replace the conventional wire electrode (WE). The discharge characteristics of the reactor under the two electrode structures were investigated and the optimal discharge parameters were determined. Under the optimum discharge parameters, the treatment effect of the two electrode structures with or without coupling Fenton reagent on oil production wastewater was also compared. The experimental results show that under the optimal discharge parameters of flow rate of 25 mL/min, plate electrode distance of 50 mm and discharge voltage of 14 kV, the reactor equipped with SWHE has higher discharge current, and the treatment effect of oil production wastewater is better when coupled with Fenton reagent.

Pilot Study on the Production of Negative Oxygen Ions Based on Lower Voltage Ionization Method and Application in Air Purification

In the current highly industrialized living environment, air quality has become an increasing public health concern. Natural environments like forests have excellent air quality due to high concentrations of negative oxygen ions originating from low-voltage ionization, without harmful ozone. Traditional negative oxygen ion generators require high voltage for corona discharge to produce ions. However, high voltage can increase electron collisions and excitations, leading to more dissociation and recombination of oxygen molecules and consequently higher ozone production. To address the challenge of generating negative oxygen ions without accompanying ozone production, this study designed and constructed a low-voltage negative oxygen ion generator based on nanometer-tip carbon fiber electrodes. The advantage of this device lies in the high curvature radius of carbon fibers, which provides high local electric field strength. This allows for efficient production of negative oxygen ions at low operating voltages without generating ozone. Experiments demonstrated that the device can efficiently generate negative oxygen ions at a working voltage as low as 2.16 kV, 28% lower than the lowest voltage reported in similar studies. The purification device manufactured in this study had a total decay constant for PM2.5 purification of 0.8967 min−1 within five minutes, compared to a natural decay constant of only 0.0438 min−1, resulting in a calculated Clean Air Delivery Rate (CADR) of 0.1535 m3/min. Within half an hour, concentrations of PM2.5, PM1, PM10, formaldehyde, and TVOC were reduced by 99.09%, 99.40%, 99.37%, 94.39%, and 99.35%, respectively, demonstrating good decay constants and CADR. These findings confirm its effectiveness in improving indoor air quality, highlighting its significant application value in air purification.

Numerical investigation of the sensible heat storage in novel electrostatic precipitators with liquid-filled collection electrodes

Heat recovery from flue gas holds significant potential for energy conservation. A strategy is proposed for recovering and storing heat in electrostatic precipitators by utilizing liquid-filled collection electrodes. In the prototype, the hollow collection electrode is connected to the heat storage tank. Convective heat transfer occurs between the gas stream and the liquid contained in the collection electrode. The heat storage mechanism is revealed by numerical simulation of corona discharge, flow and heat transfer processes in a simplified electrostatic precipitator. The results indicate that both the gas-side and liquid-side heat transfer coefficients reach steady values within approximately 100 s. The buoyancy-driven liquid flow results in a heat transfer coefficient that is 28 times higher than that for gas-side forced convection. Increasing the gas inlet temperature leads to a greater buoyancy force and, consequently, a higher heat transfer coefficient on the liquid side. Both ionic wind and inlet velocity affect the gas-side heat transfer. The ionic wind disturbs the thermal boundary layer, leading to a 27.9 % increase in the gas-side heat transfer coefficient at an inlet velocity of 0.5 m/s. Furthermore, this enhancement becomes more pronounced as the inlet velocity decreases. The flow pattern of liquid in the collection electrode and heat storage tank is crucial to the heat storage process. Additionally, installing the heat storage tank above the electrostatic precipitator provides added benefits. During the process of heat storage, the largest heat resistance is found on the gas side.

Surface degradation of epoxy resin exposed to corona discharge under bipolar square wave field: From phenomenon to the insights

The unavoidable corona discharge induced by distorted field is detrimental to the safety of power equipment, especially the equipment with high voltage magnitude and high frequency. In this paper, the degradation morphology, residual components, lifetime of endurance, partial discharge characteristics, and evolution of surface traps of epoxy insulation under bipolar square wave field is investigated. The results show that degraded zone exhibits as three layers with round pits and channel-like ravines on the surface of epoxy resin exposed to corona discharge. It is demonstrated that more oxygen element during corona discharge while more carbon element during breakdown appeared, and nano-Al2O3 fillers migrates to the discharged zone. The maximum temperature and number of emitted phonons increase with voltage amplitude and frequency in power law and exponential form, respectively, corresponding to the fitting function of endurance lifetime. The emitted light is concentrated on the near ultraviolet (UV) and infrared ray (IR) band, indicating the energy pooling and thermal effect of corona discharge, which interprets the distinct degradation behavior of samples under sinusoidal and bipolar square wave voltage. The effect of space charge and thermal conductivity should be considered simultaneously in the degradation of epoxy insulation under bipolar square wave field due to polarity reversal and high frequency, which is proved by the disparate behavior of EP/nano-Al2O3 composites resistance to corona discharge and the breakdown moment at falling edge of bipolar square wave voltage. This work may contribute to the advancement of resistance to corona discharge degradation in equipment with high power density, high voltage amplitude and high frequency.

Visualization and standardized quantification of surface charge density for triboelectric materials

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.

Probing the effect of protein corona on SERS signals: insights from melamine detection in milk matrix

Matrix effects limit the application of surface-enhanced Raman scattering (SERS) technology in the field of food safety. This study elucidated it from the perspective of protein corona by employing a model system for melamine SERS detection in milk. Compared with the melamine standard solution, higher detection limits (1 mg/L and 10 mg/L) are observed in milk matrix. The melamine signal exhibits an 80% reduction in whey protein solution, suggesting that protein has a significant impact on SERS signals. The changes in particle size, zeta potential and UV–vis spectra indicate the AuNPs interact with whey protein. Forming protein corona inhibits the melamine-induced AuNPs aggregation, reducing the number of ‘hot spot’ and the adsorption of melamine on AuNPs (from 0.28 mg/L to 0.07 mg/L), which may be responsible for signal loss. The found matrix effect from protein corona provides new insights for developing strategies about reducing matrix effect in SERS application.

Optical signals measurement of discharge plasma in air switch cabinet using a fluorescent optical fiber as the sensor

Air switch cabinets are widely employed in the power industry, there is, however, no reliable methods for detecting partial discharges (PDs). Because fiber optic-based sensors are easy to install and have anti-electromagnetic interference capabilities, they are well suited for PDs detection in switch cabinets with their many components and metal shell structure. In this work, corona discharge in an air switch cabinet was detected using fluorescent fiber, and the characteristics of PDs were analyzed. Furthermore, experimental investigations were conducted to explore the impact of gas pressure and fiber length on the PDs detection. The results exhibit a correlation between the aforementioned factors and the PDs’ total amplitude, maximum amplitude, number of pulses and detection limit of PD quantity. The results can provide references for the application of fluorescent optical fiber on the PD detection in air switch cabinet.

Portable and affordable cold air plasma source with optimized bactericidal effect

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.

What is the advantage of alternative current (AC) corona discharge for APCI mass spectrometry?

A comparative study on direct current (DC) and alternating current (AC) corona discharge ionization for positive and negative mode of operation was performed by mass spectrometry. The needle, positioned 3 mm in front of the inlet of a mass spectrometer, was moved upward and intensities of ions were measured as a function of vertical distance d. For DC corona discharge, the unipolar plasma sizes for positive and negative ions were found to be nearly the same with d ≈ ∼5 mm. In contrast, for AC corona with 15 kHz, while positive ions were found to be much more confined in a narrow region with d ≈ ∼2 mm, negative ions were detected with much larger d ≈ ∼10 mm. This marked difference of unipolar plasma sizes of positive and negative ions for AC corona was ascribed to the much larger diffusion lengths of electrons than those of positive ions. In the negative mode of DC and AC corona discharge ionization, the intensity of CH3COO− (m/z 59) originating from an acetic acid impurity was found to increase with d. This peculiar behavior was attributed to the proton transfer reaction of O2− with acetic acid vapor taking place distant from the tip of the electrode needle. The ionization efficiency of AC corona is higher than that of DC corona for both positive and negative modes of operation. The higher ionization efficiencies for AC corona are attributed to the generation of remnant electrons and positive ions for positive and negative phase AC corona, respectively. These remnant charges play crucial roles as the triggers for plasma breakdown in every cycle of RF frequency. The ion intensities measured by proximity corona discharge ionization are almost proportional to the analyte concentrations when they are less than 1 ppm.

Study on the application of atomized corona discharge combined with screen electrode in dust collection

This paper presents the design of a novel atomized corona discharge coupled screen electrode dust collector, which integrates electrostatic capture and wet electrostatic dust removal technologies. The upper part of the dust collector features an atomized corona discharge electrode utilizing a threaded-wire hole design with uniform water distribution. This design effectively addresses the issue of electrode fatness that may arise from uneven distribution of the discharge electrode. In contrast, the lower part of the collector is equipped with four side-by-side silk screen electrodes, which serve to expand the dust collection area, facilitate secondary particle capture, and consequently enhance dust removal efficiency. The study delves into a detailed analysis of the impact of various parameters on discharge characteristics and dust removal efficiency, culminating in the identification of optimal parameters.

Разработка СВЧ-установки для термообработки отходов убоя животных

Every day, the Russian Federation processes 126.3 tons of animal slaughter waste into animal feed. With an installation capacity of 35 kg/h, the required quantity is 7000 units. As a rule, the devices are energy-intensive. The problem is to reduce the operating costs of heat treatment of raw materials while maintaining the feed quality. The article introduces a new installation powered by an electrically driven resonator with rationalized operating modes. The research featured mucous by-products that require thermal treatment to neutralize the smell and disinfect the raw material. The authors investigated the dynamics of heating and used the data obtained to develop a digital installation model and test the electrodynamics in the resonator. After that, they rationalized the operating modes, i.e., corona discharge, electric field, screen efficiency, generator power, installation performance, and energy costs. The complex action of electromagnetic radiation provided a continuous combined heat treatment, disinfection, and odor neutralization with reduced operating costs. The electrical resonator was coaxially located in the shielding and contained a coronating electrode, electric bactericidal UV gas discharge lamps, knives, screws, and emitters from air-cooled magnetrons. The annular volume between the resonator and the coat excited the traveling wave by electromagnetic radiation through the perforation. Its average perimeter was a multiple of half the wavelength. The heat treatment with disinfection and fat rendering required an intrinsic quality factor of 8000, a generator power of 4.4 kW, a productivity of 35–40 kg/h, and energy costs of 0.25–0.28 kWh/kg. When the electric field was 5 kV/cm and the corona discharge was 9.79 kV/cm, the corona of bactericidal lamps provided the required ozone concentration and the bacterial contamination fell down to an acceptable level. The new installation with an electrical resonator reduced operating costs for heat treatment of animal slaughter waste and maintained the high-quality of the resulting feed products.