Characteristics Of 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.

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

Calculation of the (I-V) Characteristics of Corona Discharge in an Asymmetrical Model from Active Electrodes to Passive Electrodes

This research discusses the comparison of the formulation of the current-voltage (I-V) characteristics of symmetric and asymmetric direct current CCP equipment in the case of corona discharges in the air. The electrode configuration model taken for the symmetric CCP case is the coaxial cylinder and for the asymmetric CCP case is the plane-serrated knife. Both types of electrodes use a modified capacitance concept in the (I-V) characteristic calculations. This concept originates from a geometric approach solution (electrode sizes), where there is a corona electric current multiplier factor (corona current multiplication factor compared to conventional electric current) as well as the nature of the corona discharge which will collect at the sharp tip of the active electrode.

Impact of Cathode Geometry on Negative Corona Discharge and Trichel Pulse Characteristics: A Comparative Analysis of Hyperbolic, Elliptic, and Tangent-Circular Needle Shapes

Impact of Cathode Geometry on Negative Corona Discharge and Trichel Pulse Characteristics: A Comparative Analysis of Hyperbolic, Elliptic, and Tangent-Circular Needle Shapes

The characteristics of negative corona discharge and radio interference at different altitudes based on coaxial wire–cylinder gap

The corona discharge from transmission lines in high-altitude areas is more severe than at lower altitudes. The radio interference caused thereby is a key factor to be considered when designing transmission lines. To study the influence of altitude on negative corona characteristics, an experimental platform comprising a movable small corona cage was established: experiments were conducted at four altitudes in the range of 1120‒4320 m, and data on the corona current pulse and radio interference level of 0.8-mm diameter fine copper wire under different negative voltages were collected. The experimental results show that the average amplitude, repetition frequency and average current of the corona current pulse increase with increasing altitude. The dispersion of pulse amplitude increases with increase in altitude, while the randomness of the pulse interval decreases continuously. Taking the average current as an intermediate variable, the relationship between radio interference level and altitude is obtained. The result of this research has some significance for understanding the corona discharge characteristics of ultra-high-voltage lines.

Positive corona discharge and acoustic characteristics of stranded conductor under low air pressure and different humidities

Positive corona discharge and acoustic characteristics of stranded conductor under low air pressure and different humidities

Nonlinear evolution of space synthetic electric field in positive DC corona mode transition

Positive corona discharge in the air exists under several distinctive forms depending on DC voltage amplitude, including pulses or pulseless glow. Previous studies obtained the current and optical image characteristics of corona discharge through experiments. However, the synthesized electric field characteristics of the different corona modes have not been deeply studied by experiments, and lack of sufficient understanding of the effect of space charges. In this paper, electro-optical modulation technology is used to investigate the characteristics of the space synthetic electric field (SSE) for positive DC corona modes transition. The experimental results show the significant nonlinear evolution characteristics of the SSE and discharge modes transition with the increase of applied voltage. In the pulsed mode, the SSE first changes slowly and then increases sharply. As the applied voltage increases, the discharge mode transition from pulse mode to pulseless glow mode, while the SSE changes slowly. The electric field change rate in the sharp increase is 2–3 times that in the slow change. Dynamic accumulation behavior of space charges is the main reason for the nonlinear evolution of the SSE. When the pulse current starts, the discharge amplitude and frequency are low, and the ions are far away from the ionization region, which has little effect on the migration process of the high field strength region and subsequent ions. With the increase of the applied voltage, the continuous accumulation of positive ions enhances the migration of subsequent positive ions, thereby rapidly increasing the SSE. During the glow discharge mode, the generation and dissipation of space charges are close to dynamic equilibrium, and the fusion of multiple positive ion clouds will increase the SSE.

Effects of electron migration and adsorption on the suppression of negative corona discharge in nanoparticle transformer oil: experiments and simulations

SiO2 and TiO2 nanofluids (NFs for short) were prepared, and a series of DC corona discharge tests were carried out under needle-plate electrode on both NFs and base oil, using the luminous area and pulse current to characterize the negative corona discharge characteristics. The trap distribution characteristic as well as the mobilities of positive and negative ions of the two types of NFs and base oil were measured. A kind of new corona discharge simulation model was established, and the effects of shallow traps and electrons adsorbed by nanoparticles were considered in the simulation model. The corona discharge was simulated under the needle-plate electrode and the simulation results were compared with the corona discharge characteristics obtained from the tests. Furthermore, the effects of shallow trap and electron adsorbed by nanoparticles on space charge and electric field distribution as well as field ionization in transformer oil were analyzed respectively, revealing the mechanism that nanoparticles regulate the carrier migration process to suppress the negative corona discharge of transformer oil.

Study on filtration enhancement of a dual-layer granular bed filter for bipolar-charged dust

To improve the filtration efficiency of the dual-layer granular bed filter, a new method to enhance filtration with dust bipolar-charging was proposed. The characteristics of positive and negative corona discharge and dust charging at different temperatures were measured and analyzed. The filtration experiments of non-charged dust, positive charged dust, negative charged dust, and bipolar charged dust in a dual-layer granular bed filter were carried out. The results confirmed that the best filtration effect was achieved when the dust was bipolar-charged. Furthermore, because of the loose structure of dust cake formed by the charged dust, the filter regeneration cycles were prolonged. At 450 ℃, when the inlet dust concentration was 10 g/m3, and the bi-charging voltages were + 20 kV and - 14 kV, the mean outlet dust concentration in a filtering cycle was 38.1%, 46.6% and 68.2% lower than that of negative-charged, positive charged, and non-charged dust, respectively.

DC negative corona discharge characteristics of the needle-plate electrode under different air pressures

Because of the low normal atmospheric pressure and frequent, more severe corona discharges in high-altitude regions. The electromagnetic environment problems caused by the corona discharge restrict the line design in high-altitude areas. The variance in the law of negative DC corona characteristics under different air pressure conditions is derived using an artificial climate tank with adjustable air pressure. The characteristics of the negative DC needle-plate corona discharge were measured experimentally. The negative DC corona discharge pulses at 89.4 kPa–56.04 kPa were obtained, and the characteristics of the current pulses were statistically examined. The study of the mechanism of the DC corona discharge can benefit from the research findings as essential reference data.

The characteristics of positive corona discharge at different altitudes

With the vigorous growth of UHV transmission projects, transmission lines crossing high-altitude areas are inevitable, and the degree of corona discharge in high-altitude areas is more intense. The electromagnetic environmental problems caused by corona discharge have gradually become one of the key technical problems restricting UHV transmission in high-altitude areas. To investigate how height affects the positive polarity corona’s corona characteristics, using the movable small corona cage to carry out experiments at four altitude points in the range of 1120 m–4320 m, and measures the corona current pulse and radio interference level of 0.8 mm diameter fine copper wire under different positive voltages. Several conclusions can be drawn from the data analysis, including the following: The average current pulse amplitude grows with altitude, first before decreasing, and the current pulse repetition frequency rises along with altitude. The major conclusions of this essay can serve as a starting point for the study of the corona effect.

Spatiotemporal corona discharge characteristics of nanoelectrode: array carbon nanotubes

Corona discharge is a widely-used phenomenon that requires a sharp electrode to generate a strong electric field (106 V m−1) at high voltages (typically in the tens of kV). The advent of nanoelectrodes has overcome the technical limitations of traditional electrodes, dramatically improving the density of discharge points and enabling low voltage (several kV) corona discharges with nanometer-sized tips. Consequently, nanoelectrode discharge technology has the potential to revolutionize the miniaturization of plasma equipment in the future. However, research on the discharge characteristics of nanoelectrodes is still relatively sparse. This paper focuses on an array of carbon nanotubes (ACNTs) and proposes a numerical simulation model based on the hybrid hydrodynamics model and ion migration model. The accuracy and efficiency of this model are demonstrated by a high degree of agreement between the results from numerical simulations and experiments. In addition, the corona discharge characteristics of ACNTs are studied and discussed, particularly the spatiotemporal evolution of charged particles near the tip. This paper may provide a method of analysis for optimizing and broadly applying nanoelectrodes.

Trichel pulse characteristics and mechanism of negative corona discharge in sub-millimeter gaps

A negative corona discharge system of a needle-plate electrode suitable for sub-millimeter gaps is established to investigate Trichel pulse characteristics of negative corona discharge, in which an optical acquisition system is especially applied to timely observe a discharging corona. Electrostatics–hydrodynamics coupling simulations of air discharging in 100 μm-gaped needle-plate electrodes are performed to elucidate the micro-physical process of negative corona discharge. The impact ionization coefficient used for simulations and the experimentally recorded images of discharge corona are combined to characterize the active region of secondary electron emission. Dynamical distribution and transport of the charged particles are analyzed from multiphysics simulations to explain the microscopic mechanism for various stages of Trichel pulses. Even though the corona front near the plate electrode maintains a high rate of collision ionization and secondary electron excitation, the needle tip corona has not reached the threshold electric field of electron avalanche required for glow discharge, as manifested by discharge sawtooth waves comprised of corona and glow components. The amplitude and frequency of Trichel pulses increase, respectively, with impact ionization and secondary electron emission, which is evidently dependent on attachment coefficient and anion mobility. A higher attachment coefficient will lead to a significant reduction in amplitude of Trichel pulses. The present study provides a theoretical basis and experimental verification for micrometer discharges, which is the key point of insulation protections in microelectromechanical systems.

Experimental and numerical modeling of DC corona discharge in Wire-Cylinder-Plane configuration

The aim of this paper is to present a numerical and experimental study of the positive corona discharge in the Wire-Cylinder-Plane geometry intended for electrostatic charging of insulating materials. A detailed experimental procedure is described to determine the corona discharge characteristics where different electrode layouts have been tested to improve the performance of the charge process. In addition, the corona governing equations are successfully implemented and solved in the studied geometry using Comsol Multiphysics Software. The study focused on the effect of the presence of the non-ionizing cylinder on the coronating wire. It has been found that increasing the diameter of the cylinder or bringing it closer to the wire reinforces the shielding effect between the two electrodes, which results in the reduction of the corona current and current density at the level of the measurement plane. The measured I–V characteristics and current density distributions were found to be in good agreement with the corresponding numerical predictions.

Research on the shielding effect of the electrode frames in the electrostatic precipitator

ABSTRACT The electrostatic precipitator (ESP) plays an important role in the dust removal from the flue gas. Currently, the shielding effect of electrode frames seriously affects the electric field distribution and dust removal efficiency of ESPs. In order to explore the shielding effect and propose an improved measurement, an experimental setup with RS barbed electrodes and a 480 C type dust collector electrode plate was built to evaluate the corona discharge characteristics. The current density distribution on the surface of the collecting plate was tested on an ESP experimental setup. The effect of electrode frames on the current density distribution was also systematically investigated. The test results show that the current density distribution on the position that directly opposites the needle of RS corona discharge is much higher, on the contrary, the current density on the position that directly opposites the frames is almost zero. It indicates that the frames have a shielding effect on the corona discharge. Therefore, the dust collection efficiency is low in actual ESPs due to the dust escape route caused by the shielding effect. To solve the problem, a new ESP with a split-level frame arrangement was proposed. Implications: The conventional electrostatic precipitators are often affected by the electrostatic shielding effect, which leads to uneven charging. The particulate removal efficiency decreases and escape channels are very easy to form. In this study, effective measures were proposed to solve the electrostatic shielding of dust collector frames by studying their electrostatic shielding mechanism. The study provides theoretical support for the improvement of electrostatic precipitators, while improving the dust removal efficiency.

Three-Dimensional Simulation of Corona Discharge in a Double-Needle System during a Thunderstorm

The effect of corona discharge from buildings or structures on the surrounding atmospheric electric field is very important in the measurement of urban atmospheric electric fields and the early warning of lightning. However, most previous studies were focused on independent buildings, with little research on three-dimensional building groups. Therefore, based on three-dimensional numerical simulation technology, this paper uses a double-needle system to simulate the characteristics of thunderstorm corona discharge from two equal-height buildings separated by a variable distance. The shielding effect of the double-needle system on the ground electric field is evaluated both with and without corona discharge, and the main conclusions are as follows: (1) The larger the distance between the two needles, the closer the peak corona current from each tip of the double-needle system is to that from an independent lightning rod at the same height. When the peak corona current from each tip of the double-needle system equals the peak corona current from an independent lightning rod at the same height to some level of approximation, the distance between the two needle systems is determined by the needle height at this time. (2) If the distance between the two needles is 0.1 m, the corona charge released by the double-needle system is almost equal to that released by an independent lightning rod. The corona charge released by the double-needle system is approximately twice as much as that released by an independent lightning rod when the distance between the two needles is increased to a certain value that increases with the needle height and the time of corona discharge. (3) The greater the value of the time of corona discharge, the stronger the shielding effect of the corona discharge on the ground electric field and the larger the shielding range, but the greater the value of the needle height, the smaller the shielding range. (4) Compared with the shielding effect with no corona discharge, that with corona discharge is greater, but the greater the value of the needle height, the less the enhancement. For example, for corona discharge with a time of 10 s, the needle height is 20 m, and the shielding range is ca. 70 m, which is 8.8 times that without corona discharge; however, for the needle height of 100 m, the shielding range is ca. 150 m, which is only 1.5 times that without corona discharge.

Particle-Triggered Corona Discharge Characteristics in Air Insulation Under DC Voltage

Under a dc stress, a wire particle within gas insulation will exhibit complex motion behavior, leading to more challenges to detect its existence. Therefore, this work deals with an investigation of corona discharge characteristics generated from a wire particle with different particle positions in an air gap. Three different wire particles are prepared in this investigation. The particle is placed between parallel-plane electrodes with a fixed gap of 20 mm. Five different positions are evaluated to study the partial discharge (PD) behavior generated from the wire particle. The exponential probability distribution is used to evaluate the pulse occurrences from different positions. Pulse sequence analysis (PSA) technique is employed, and an interpretation algorithm is introduced to understand the discharge pattern. The results show that each of the particle positions creates a unique pattern, which discharge mechanism behind the pattern is explained. From the pattern observation, a wire particle has single cluster of corona type as attached to the electrode while multiclusters are found when it is floating in the gap. Moreover, it is also found that different particle lengths are also affecting the discharge pattern characteristic.

Experimental study on positive corona discharge characteristics in plane-single/double earthed rods air gaps under negative DC voltage

In order to analyze the corona discharge characteristics at the grounding object tip under the thundercloud electric field environment, scaled simulation test has been conducted on corona discharge in the plane-single/double earthed rods air gap. Five gap configurations with three different grounding rods were built during experiments. Factors as rod tip curvature, voltage and gap configuration have been considered in detail. Corona voltage, corona current and the number of ultraviolet photons were all recorded. The grounding rod tip curvature radius can affect corona discharge processes at grounding rod tip. With increasing applied negative DC voltage, five typical corona processes of dark discharge, burst streamer corona, periodic streamer corona, glow corona and brush discharge occurred at conical and spherical grounding rod tip (r=0.75cm), but under d=5cm and d=10cm no glow corona and brush corona appeared at spherical grounding rod tip (r=1.25cm). It is much easier for grounding rod tip with smaller curvature to form glow corona phenomenon. The mean value Iav of periodic streamer corona current pulse amplitude decreases with grounding rod tip curvature radius, while the mean corona current pulse width and pulse interval increases. For grounding rod with conical tip, there is little difference of average current pulse amplitude between periodic streamer corona and brush corona; for grounding rod with spherical tip (r=0.75cm), the mean value Iav of brush corona pulse amplitude increases to 3595.8 μA which has increased by a factor of about 36. The photon number at conical grounding rod tip is larger than that at spherical grounding rod tip at low voltage but the relation reverses as the applied voltage exceeds a critical value. The shielding effect of two grounding rods in plane-double rods air gaps increased with spherical grounding rod curvature radius and decreases with the lateral gap distance between two grounding rods.

Effect of Magnetic Field on Corona Discharge Under Airflow

Corona discharge under airflow is extensively researched due to its wide applications in the fields of electrostatic precipitator, flow control, thermal management, and so on. The adjustment of discharge characteristics has been an important research topic in recent years. In this article, a magnetic field is applied as a method to adjust the characteristics of corona discharge under airflow. The experimental result illustrates that the intensity and direction of the magnetic field would influence the turning point of the discharge state under airflow, and the corresponding discharge image and Trichel pulse characteristics, such as amplitude and frequency, would also be changed. The physical mechanism for this phenomenon is analyzed by considering the magnetic force of the corona discharge. With increasing magnetic field intensity, the pressure in the discharge space would change and the airflow state and the discharge process, as the ionization process and the attachment process, would be influenced. The overall characteristics of discharge under airflow would be adjusted by the magnetic field. The results illustrated that the magnetic field is possibly utilized to improve the application of corona discharge under airflow.

EFFECT OF THE EXCITED VOLTAGE RISE TIME ON THE CORONA DISCHARGE CHARACTERISTICS

In this paper, the rise time of the exciting voltage on the DC corona discharge characteristics in a coaxial electrode system is presented. The current one-dimensional simulation study focused on the distribution of the plasma species (ions and electrons as well as the excited atoms) during two different times of the applied voltage climb was classified as a fast rise time (615 ns) and a slow rise time (2710 ns). The growth time of the corona excited voltage was controlled by the external feed RC circuit that connected with the central electrode. The simulation results reveal that the corona inception which occurs at a fast rise time produces more dense plasma charged species, while the density of the excited atoms is not much affected by the applied voltage climb time. The density of excited atoms tends to depend on the rise time of the exciting voltage at the steady state.