Electric Field Strength Distribution Research Articles

Temperature and electric field distribution of tri‐post insulator in DC‐GIL based on numerical multiphysics modelling

AbstractThe temperature distribution of the tri‐post insulator in a ±500 kV direct current gas‐insulated transmission lines (DC‐GIL) is investigated. The influence of thermal gradient on the electric field characteristics is investigated as well. A horizontally installed GIL model is applied in the simulation. The thermal and electric parameters of the insulator are measured and employed. The temperature results indicate that the gas shows a layered distribution pattern while the insulator shows a radial distribution pattern. The temperature of the upper post is higher. With increasing ambient temperature, the surface temperature increases linearly following the variation of ambient temperature. With increasing load current, the temperature near the conductor shows an obvious increase. With increasing gas pressure, the temperature decreases due to the promotion of convection. Besides, the electric field strength of the insulator surface increases if the surface temperature increases during the variation of operating conditions. And the peak of field strength moves towards the enclosure. After 10 h, the temperature reaches a quasi‐stationary state. Since the thermal gradient affects the distribution of gas density and electric field strength of the insulator, the investigation of temperature characteristics is necessary when evaluating the insulating performance of DC‐GIL with insulators.

ЗМЕНШЕННЯ ВТРАТ НА КОРОНУ НА ПОВІТРЯНИХ ЛІНІЯХ ЕЛЕКТРОПЕРЕДАВАННЯ ЗА РАХУНОК ВИКОРИСТАННЯ СУЧАСНИХ КОНСТРУКЦІЙ ПРОВОДІВ

The analysis of the conducted studies of the operation of high-voltage power lines (LEP) showed that the maximum power losses per corona are characteristic of increased voltages on high-voltage power lines with their low load, as well as in bad weather. Thus, a 5% increase in voltage at low line load leads to an increase in power losses per corona up to 30%. When it rains, power losses per corona for a 330 kV transmission line increase by 10 times compared to losses in good weather, for a 500 kV transmission line, the increase in losses is 12 times, and for a 750 kV transmission line - 13 times. During frost, the maximum power losses per crown are observed, which for a 330 kV transmission line increase by 23 times compared to losses in good weather, for a 500 kV transmission line, the increase in losses is 25 times, and for a 750 kV transmission line - 21 times. It should be noted that deterioration of weather conditions, in which there is an increase in corona power losses, is observed for more than 20% of the entire period of operation of the transmission lines during the year. Under such conditions, more than 80% of the total power losses per corona in the transmission line occur. The development and implementation of organizational and technical measures aimed at reducing power losses at the crown of power lines is an important practical task, the solution of which will contribute to increasing the efficiency of the electrical networks of Ukraine. Studying the possibility of influencing the amount of power losses due to the use of modern wire designs is an urgent task at the stage of designing power lines. The use of innovative brands of wires can lead to an increase in power losses per corona, due to their design features. Heat-shrinking films can be used to apply an insulating layer to sections of power lines, which will prevent corona and reduce losses associated with it. It is necessary to study the distribution of electric field strength along the span of the transmission line to determine the quantitative indicators of power losses per corona

Numerical Simulation and Calculation of Resistance of Laminated Paper-Impregnated Insulation of Power Cables

Numerical simulation of polypropylene laminated paper insulation is a serious challenge, as it must take into account the layered structure and presence of longitudinal and radial gaps in the coils of the winded tape for cables with sector-shape conductive cores. Thus far, it has been performed only with serious simplifications. We propose a technique for numerical modeling of electric parameters in this type of insulation by reducing a complex 3D problem to a simplified 2D model that takes into account the main influencing factors. The results of modeling the distribution of electric field strength and current density in insulation are presented, and the influence of the location of gaps between the edges of winded tape on the conductivity of cable insulation is estimated. Analytical expressions are obtained for estimating the electrical resistance of insulation while taking into account the parameters of the butt gap between the insulating tapes. The results of calculations, numerical modeling, and experimentally measured values of electrical resistance are compared, showing that there is a good match. The main effects affecting the properties of polypropylene laminated paper insulation are described.

The features of surface charging on rectangle mask holes in plasma etching

In the plasma etching technique, acquiring a high-quality transfer from the mask pattern onto the substrate under the suppression of the charging effects is of great significance. Most previous publications only focus on studying the charging phenomena on round mask holes. This work shifted the target to an isolated rectangle mask hole and two types of mask arrays (quadrangle and hexagonal arrays). A classical particle simulation program was used. This study first shows that rectangle holes with various ratios of length and width present different electric field (E-field) strength distribution around the long and short sides. The larger the ratio, the stronger the E-field in the long side is than that in the short one. In addition, the E-field shows a quite weak distribution at the vertexes, which is due to the low curvature of the vertexes. Based on the evolutions of E-field and the simulated profile with time, it is indicated that ions would give priority to bombard the long side rather than the short side and vertexes, forcing the sides to deform outward as arcs. Unlike an isolated mask hole, the mask array has a remarkable influence on the charging effects in case of the close distance between holes. Simply put, the quadrangle and hexagonal arrays relieve and worsen the non-uniformity of the distribution of the E-field at the edge of a rectangle mask hole, respectively. The simulated profile evolution further proves those speculations based on the E-field distribution. Possible mechanisms behind this have been discussed in detail. The findings of this work help arrange an appropriate mask pattern according to the specific mask shape, which would shed light on a way of maintaining the pattern integrity.

Coverage and Performance Evaluation of VHF and UHF Electric Field Strength Distribution in Urban Area of Ilorin, Nigeria

This paper evaluated the coverage and performance of VHF and UHF signal level from two different transmission stations in the urban area of Ilorin, Kwara State, Nigeria. The performance characteristics of the two bands are of special importance regarding coverage and quality requirements. Effective communication links require direct line of sight; however, this cannot be achieved in a build-up areas where obstacles are present along the communication paths, which in turns result in signal strength degradation. In this work, the signal strength and performance of Nigeria Television Authority (NTA), Ilorin, and Kwara State Television (KWTV) were investigated along some six selected routes. The measurement was taken with a spectrum analyzer. Global positioning system (GPS) device was used to measure the coordinates between the transmitter and receiver during measurement. Microsoft Excel software was used to show the graphical variation of the field strength. Furthermore, the result obtained reveal the performance of the two transmitting stations under National Broadcasting Commission (NBC) and Federal Communication Commission (FCC) thresholds, the highest percentage coverage recorded from the two stations along route 3 are 66.48% for VHF and 6.92% for UHF. The need for repeater stations was suggested to routes with poor coverage so as to improve the signal quality based on NBC standard.

Simulation of the electric field of a polymer bushing in the Ansys Maxwell software environment

The article analyses the software tools for modelling the maps of the electric field strength of insulators. The need to address this issue is dictated by the fact that the uneven electric field on the insulators increases the probability of partial discharges that destroy the insulating layer, so it is very important to optimize the electric field strength on the insulator. The design features of bushings and features of partial discharges in them are considered. The distribution of electric field strength in a polymer pass-through operating in an AC network without contaminants is considered. The results of modelling the electric field of insulators in the software environment Ansys Maxwell, which is based on the simulation of the finite element method, are presented. Points in the construction of a 35 kV bushing polymer insulator have been identified, where the highest level of electric field strength is concentrated. A method of influencing the area under study in the area of the flange connection to the ground plate is proposed. This defines the use of a conductive cover placed between the flange and the place of connection to the polymeric insulating layer, which significantly improves the overall electric field strength distribution on the surface of the bushing polymer insulator and makes it competitive compared to the most commonly used porcelain bushings, by increasing the electrical strength of the structure. According to the results of research, a means of optimizing the electric field of the pass-through polymer insulator is proposed, which allows to increase its electric resistance and reduce the electric field strength in the area of flange contact with the mounting surface, which in turn prevents premature partial discharges in the insulating bodies.

Relationship between Electric Field Strength Distribution and Dielectric Breakdown Points in Insulating Substrates of Power Modules

Relationship between Electric Field Strength Distribution and Dielectric Breakdown Points in Insulating Substrates of Power Modules

Design and Characterization of Wideband Terahertz Metamaterial Stop-Band Filter.

We propose and design a metamaterial broadband stop-band filter with a steep cut-off in the terahertz region. The filter is based on the flexible structure of metal-dielectric-metal-dielectric-metal (MDMDM). Simulation results show that the filter has a center frequency of 1.08 THz, the square ratio reaches 0.95, and the −20 dB bandwidth reaches 1.07 THz. In addition, it has excellent flat-top characteristics with an average transmission rate in the resistive band of no more than 5%. The relative bandwidth has been up to 99%, and stopband absorption rate has reached more than 98%. The effects of the main structural parameters on the transmission characteristics are discussed. The role of each layer of metal in the filter is explored by studying the effect of the variation of the number of metal layers on the filter. The symmetry of the structure ensures the polarization insensitivity of the filter at normal incidence. The correctness of the simulation results was verified by analyzing the effective permittivity and magnetic permeability. To investigate the transmission characteristics of the metamaterial filter in-depth, we analyzed the electric field strength and surface current distribution at the center frequency of the filter. The designed terahertz filter may have potential applications in terahertz communications, sensors, and emerging terahertz technologies.

Control of The Distribution of The Internal Characteristics of The Discharge Using Supersonic Gas Pumping

Theoretical studies of the distribution of glow discharge parameters in a supersonic nitrogen gas flow between the central body of the nozzle and an annular electrode around the central body are carried out. Distributions of charged particle concentrations, potential, and electric field strength are obtained. The possibility of compaction or stretching of the cathode zones has been demonstrated. In the case of the organization of a supersonic gas flow near the central body-the anode, all the near-electrode zones are pressed against the anode. In this case, the cathode is located in the area of reduced pressures. Such a way of organizing the discharge can find application in the processes of applying functional coatings.

Simulation of Electrooptical Measurements of Prebreakdown Electric Fields in Water—Part I: Electric Field Near Anode Streamer

The analysis of the results of electrooptical measurements using the Kerr effect at the prebreakdown stage of an electric discharge in water made it possible to estimate the intensity of the inception field of the anode streamer. The electric field strength and phase difference distribution were constructed using computer simulation in the point-to-plane system near the anode tip. The conditions of an actual experiment are simulated. It turned out that taking into account the nonlinearity of the relative permittivity and saturation of polarization leads to a sharp increase in the field strength in a narrow region near the needle tip and compression of both the strong field region and compression of Kerr fringes. Taking these factors into account made it possible to explain the unusual shape of the chronogram and to estimate the field strength of the appearance of the anode streamer as <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$E$ </tex-math></inline-formula> ~ 40–50 MV/cm.

High harmonics generation in gases near the gratings: towards the spectrum enhancement and enrichment

The problem of harmonic generation efficiency (as an example of non-linear optical phenomena) increasing by atomic media near the surface of a one-dimensional metal diffraction grating under conditions of plasmon resonance excitation is considered. The local field enhancement factor dependences on diffraction grating profile are studied. Spatial distribution of the femtosecond pulse electric field strength over the grating surface under conditions of plasmon resonance excitation is simulated. Generated harmonic efficiency enhancement and photoemission spectra enrichment (due to laser field strength amplification near the grating) are discussed.

The Effect of Corona Wire Position and Radius in a Duct-Type ESP with Wavy Collecting Plates

Electrostatic precipitators (ESPs) have become one of the most effective methods for removing harmful particles from various industries. Many investigations in this subject are constantly developing due to the inherent benefits of using an ESP, and there are many robust initiatives taking place today all over the world. Different configurations of collection and discharging electrodes must be investigated to improve the ESP performance of ESPs. Many studies are working to enhance existing models in different ways. The geometry of the electrodes and the collecting plates is one area that could be improved. This paper investigates the wavy designs of collecting electrodes with varied corona electrode radius (range of variable corona radius (0.07-0.6 mm)) and position in a single-stage ESP. Wavy plates (WPs) and Inverted wavy plates (InvWPs) are compared to flat plates (FPs) using a numerical simulation tool. The results of this work show the impact of changing the corona radius when wavy and inverted wavy collecting electrodes are used on the electric potential, electric field strength, current density, and space charge density distribution, and particle collection efficiency. When compared to InvWPs and FPs, WPs show the highest performance in this range of particles. Although InvWPs can be utilized to reduce current density or space charge density, they do not increase particle collection efficiency.

Characteristics of HEMP Radiation Field on Typical Transport Aircraft with Frequency Sweep Method

This paper presents characteristics of the HEMP radiation field on a typical transport aircraft using the frequency sweep method. Firstly, the characteristics of the HEMP field are analyzed. Then, various parameters including the electric field strength and magnetic field strength distribution are calculated using Altair FEKO software. Afterwards, the electric field strength distributions of three layers (top layer, inner layer and bottom layer) are calculated and analyzed. The results indicate that the HEMP induced field is affected by the aircraft body. The induced electric field strength E(t) varies greatly at different positions. Nevertheless, the peak value of E(t) is usually greater than the initial peak value of electric field strength E0. Such a study can provide guidance and insight into the protection design of the HEMP of the aircraft.

Effects of ultrahigh permittivity ceramic on water freezing by high voltage electric field-assisted freezing system

• High voltage electric field-assisted freezing (HVEFF) on water sample was studied. • Ultra-high permittivity ceramic (UHPC) was used for the 1 st time in the freezing. • Decreasing percentage of supercooling degree was 90.3% under UHPC-HVEFF at 9 kV. • UHPC greatly improved water freezing performance when integrated to HVEFF. • UHPC possessed potentials for enlarging the sample-treating capacity of HVEFF. To investigate the effect of ultra-high permittivity ceramic (UHPC) on water freezing, a UHPC-based high voltage electric field-assisted freezing system (UHPC-HVEFF) and a low permittivity acrylic-based high voltage electric field-assisted freezing system (LPA-HVEFF) were developed. The freezing behaviours of water under UHPC-HVEFF and LPA-HVEFF at 0, 3, 6, 9 kV were comparatively studied. Hierarchical cluster analysis (HCA) was used to visualize the difference between UHPC-HVEFF and LPA-HVEFF. COMSOL was used to simulate the distribution of electric field strength in the water sample under HVEF. It was found that the decreasing percentage of the supercooling degree of the water reached 34.9%, 89.2% and 90.3% under UHPC-HVEFF at 3, 6 and 9 kV, respectively, whereas those were only 2.40%, 10.4% and 24.6% under LPA-HVEFF at 3, 6 and 9 kV, respectively. Results from the simulation indicated that the electric field strength in the water under UHPC-HVEFF was on average 11.7-7.5 times that of LPA-HVEFF, thus contributing to the high freezing efficiency of UHPC-HVEFF. This study indicated that UHPC possessed great potential to increase the sample-treating capacity of HVEF-assisted freezing system.

A novel anode structure for diffuse arc anode attachment

A novel method for adjusting the direct current arc anode attachment mode by changing the anode surface structure is proposed. A transferred arc device is used to investigate the effect on the arc anode attachment state of the electrode separation and the presence and dimensions of an annular boss, or embossing, on the anode. The experimental results show the diffuse arc anode attachment mode is more likely to be formed in the presence of an annular boss structure on the anode, compared to the standard planar structure. In the case of argon working gas, as the distance between the cathode and the anode increases from 15 mm to 30 mm, the arc maintains the diffuse arc attachment on the anode with the annular boss, while for a planar anode, the arc anode attachment mode changes from diffuse to constricted. Comparison of the measured temperature distribution by the relative intensity method and the emission intensity of the arc attachment region verifies that the annular boss anode can indeed promote diffuse attachment. Analysis of the electric field strength distribution between the electrodes shows that the introduction of the annular boss doubles the electric field strength near the anode surface due to the boss edge effect, which drives the arc to be evenly dispersed on the boss, resulting in the formation of diffuse arc attachment. The enlarged attachment area reduces the current density and heat flux on the anode surface, which is important for the stabilization of diffuse arc attachment. No obvious ablation is found on the surface of the annular boss anode after 1 h operation, while there significant ablation is evident on the surface of the planar anode.

Generation of runaway electrons in plasma after a breakdown of a gap with a sharply non-uniform electric field strength distribution

The paper is devoted to the study of the initiation and formation of a negative streamer in a sharply inhomogeneous electric field and the generation of runaway electrons (REs) in air and helium at atmospheric pressure and below, as well as in sulfur hexafluoride at low pressure. Nanosecond voltage pulses of negative polarity with an amplitude of 18 kV were applied across a point-to-plane gap 8.5 mm long. The studies were carried out using broadband measuring sensors and equipment with picosecond time resolution, as well as using a four-channel ICCD camera. Using a special method for measuring the dynamic displacement current caused by the redistribution of the electric field during streamer formation, the waveforms of voltage, discharge current, RE current, and dynamic displacement current were synchronized to each other, as well as to ICCD images. Data on the generation of REs with respect to the dynamics of streamer formation were obtained. It was found that REs are generated not only during the breakdown of the gap, but also after that. It has been found that the formation time of explosive emission centers affects the generation of REs after breakdown. Based on the measurement data of the voltage, discharge current, and dynamic displacement current, the electron concentration in the plasma channel after breakdown and the electric field strength near the surface of the grounded electrode were calculated.

Application of $$\hbox {GK}^{{\mathbf {1}}} \Sigma ^{+}_{\mathbf {g}}$$, $$\nu ' = 0 \rightarrow \hbox {B}^{1} \Sigma ^{+}_{\mathbf {u}}$$, $$\nu '' = 0$$ hydrogen band for the axial temperature measurement in the cathode sheath region of an abnormal glow discharge

In this paper, optical emission spectroscopy technique was used to measure rotational and gas temperature distribution in the cathode-sheath region of an abnormal glow discharge operated in hydrogen and hydrogen–argon mixtures. The rotational temperature of excited electronic states of H $$_{\mathrm {2}}$$ was determined from the R-branch of the $$\hbox {GK}^{\mathrm {1}}\Sigma ^{\mathrm {+}}_{g}$$ , $$\nu '= 0 \rightarrow \hbox {B}^{\mathrm {1}}\Sigma ^{\mathrm {+}}_{u}$$ , $$\nu ''=0$$ band and compared with published results for the Q-branch of the Fulcher- $$\alpha $$ diagonal band $$\hbox {d}^{\mathrm {3}}\Pi ^{\mathrm {-}}_{\mathrm {u}}$$ , $$\nu ' \rightarrow $$ $$\hbox {a}^{\mathrm {3}}\Sigma ^{\mathrm {+}}_{\mathrm {g}}$$ , $$\nu '' (\nu '=\nu ''=0$$ ). The population of excited energy levels, determined from the relative line intensities, was used to derive the rotational temperature of the ground state of hydrogen molecule. The boundary between the cathode sheath and negative glow region is determined using Stark polarization spectroscopy of the hydrogen Balmer alpha line. The thickness of the cathode sheath is estimated by fitting the experimentally determined distribution of electric field strength to a suitable model function. Temperature distributions along the axis of the cathode sheath are also reported and discussed. The distributions of temperature show that both bands give consistent and reasonable values for the rotational temperature and they both mutually agree within the estimated experimental uncertainties of 15%. The reported results contribute to the development of the spectroscopic method for gas temperature measurement in pure molecular hydrogen and in the gas mixture with argon.

Study of the Ar II spectral line shape in the cathode sheath region of glow discharge

We present the results of an experimental study of Ar II line shapes emitted side-on from the cathode sheath (CS) region of an abnormal glow discharge operating in pure argon with different cathode materials. The shape of Ar II lines is recorded side-on to the discharge axis and parallel to the plane cathode surface by using the optical emission spectroscopy technique. Our experimental line shape analysis shows that the atomic line shapes can be used for determination of the electric field strength distribution and the thickness of the CS region, whereas the broadened wings of the Ar II lines provide an insight into line shape formation as a result of electric field strength distribution, which is essential for discharge particle dynamics, and interaction with the discharge gas and sputtered cathode material. The results are summarized in two analytic formulas: one for the half width of wings as a function of the cathode distance from the recording position and the other for correlation between Ar II line width and electric field strength.

Numerical FDTD-based simulations and Raman experiments of femtosecond LIPSS.

The article describes the results of finite-difference time-domain (FDTD) mathematical modeling of electric field strength distribution near the gold laser-induced periodic surface structures (LIPSS). Both theoretical and experimental results have been described for two fabricated morphologies: round «hill-like» and grating structures. The structures were fabricated by using a femtosecond Yb-fiber laser with a wavelength of λ=1032 nm, pulse duration τ=280 fs, and repetition rate υ=25 kHz. Morphological properties of the surfaces have been investigated by means of scanning electron microscopy (SEM). The plasmonic activity was analyzed by means of the surface-enhanced Raman spectroscopy (SERS) technique. FDTD-calculated electric field values were converted into the electromagnetic field enhancement coefficient and the theoretical SERS intensity. The prospects of the theoretical approach for LIPSS to evaluate optimal field amplification and light scattering parameters has been shown. The presented approach could be applied as a basis for performing the methods of controlled synthesis for LIPPS.

Ne II spectral lines in the cathode sheath of an abnormal glow discharge

We report the results of an experimental study of Ne II 369.421 nm, 371.308 nm, and 372.711 nm spectral line shapes by means of the optical emission spectroscopy The spectral lines are recorded in the cathode sheath region of an abnormal glow discharge operated in pure neon and by using different cathode materials: copper (Cu), iron (Fe), and titanium (Ti). The studied lines have complex spectral profiles which enabled us to determine important discharge parameters. In this work we present the correlation between the width of pedestals of the side-on recorded Ne II spectral lines and the electric field strength distribution as well as the correlation between line pedestal width and the distance of the recording position from the cathode.