Calculation Of Electrostatic Field Research Articles

Dicing Process for 4H-SiC Wafers by Plasma Etching Using High-Pressure SF<sub>6</sub> Plasma with Metal Masks

Since SiC is hard and brittle, dicing by normal grinding process not only requires a long time for processing, but also reduces chip strength due to microcracks. The use of highly efficient and damage-free etching with high-pressure plasma as a chemical processing method for dicing rather than mechanical processing was investigated. The results of groove processing using a combination of a metal mask with slit-like apertures and plasma etching with high-pressure SF6 plasma showed that the processing speed decreased with decreasing slit width and increasing groove depth. The results of electrostatic field calculations suggest that this is due to a decrease in plasma intensity caused by electric field decreasing.

Integral Equations of the First Kind for Calculating Electro- and Magnetostatic Fields Perturbed by Conductors and Ferro-Magnets

The aim of the study was to develop a methodology for calculating and optimizing devices for the magnetic exploration of fossils containing materials with a high magnetic permeability. The proposed technique is based on the calculation of electrostatic fields perturbed by conducting bodies and of magnetic fields perturbed by ferromagnets with a high magnetic permeability. It uses an integral equation of the first kind. This technique is preferable to the technique consisting in the use of an integral equation of the second kind, since in the situation under consideration, the latter does not have a unique solution and requires transformation. Prospects for the development of this area allow one to bring geophysical services to the service market on a new scientific and technical production level; reduce the environmental burden on nature by replacing magnetometric measurements with energy-saving, environmentally safe technology; and ensure the export potential of magnetometric equipment.

Calculation of Electrostatic Potential Field of Coronavirus S Proteins for Brownian Dynamics Simulations

Calculation of Electrostatic Potential Field of Coronavirus S Proteins for Brownian Dynamics Simulations

Analysis of the Influence of Electrostatic Probe on Surface Charge Measurements

The electrostatic probe is among the most popular methods to measure the surface charge. However, the probe influences the surface charge distribution on the sample, which increases measurement error. In this paper, the electrostatic probe system is modeled to study its effect on surface charges on a circular conductor plate using electrostatic field calculation. The influence of the probe on the sample surface charges is found to increase with a decrease in the measurement distance, whereas it has a similar effect on surface charge density at different radial positions. A calibration process is proposed to measure the potential from the induced potential of the probe head. Using the measured potential, we calculate the surface charge density via the method of moments. The measurement error is analyzed when the measurement distance and number of rings are changed. The authors find that the number of rings should be appropriately reduced when the measurement distance increases to ensure the accuracy of the calculations. This research provides theoretical guidance for using the electrostatic probe and establishing a surface charge measurements system. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Pre-Existing Oxidative Stress Creates a Docking-Ready Conformation of the SARS-CoV-2 Receptor-Binding Domain.

The redox-dependent changes on the binding between the receptor-binding domain of the severe acute respiratory syndrome-coronavirus-2 spike protein and the peptidase domain of the human cell surface receptor angiotensin-converting enzyme II were investigated by performing molecular dynamics simulations. The reduced states of the protein partners were generated in silico by converting the disulfides to thiols. The role of redox transformation on the protein–protein binding affinity was assessed from the time-evolved structures after 200 ns simulations using electrostatic field calculations and implicit solvation. The present simulations revealed that the bending motion at the protein–protein interface is significantly altered when the disulfides are reduced to thiols. In the native complex, the presence of disulfide bonds preserves the structural complementarity of the protein partners and maintains the intrinsic conformational dynamics. Also, the study demonstrates that when already bound, the disulfide-to-thiol conversion of the receptor-binding domain has a limited impact on the binding of the spike protein to the receptor. However, if the reduction occurs before binding to the receptor, a spectacular conformational change of the receptor-binding domain occurs that fully impairs the binding. In other words, the formation of disulfide bonds, prevalent during oxidative stress, creates a conformation ready to bind to the receptor. Taken together, the present study demonstrates the role of pre-existing oxidative stress in elevating the binding affinity of the spike protein for the human receptor, offering future clues for alternate therapeutic possibilities.

Electrostatic potential and electric field in the z axis of a non centered circular charged ring

In introductory level electromagnetism courses the calculation of electrostatic potential and electric field in an arbitrary point is a very common exercise. One of the most viewed cases is the calculation of electrostatic potential and electric field in the symmetry axis of a centered ring and it has been widely studied the potential off the axis of a charged ring centered in the origin coordinate. In this work, we calculated the electrostatic potential and electric field in the z axis of a non centered charged ring using elliptic integrals as an pedagogical example of the application of special functions in electromagnetism.

The Hybrid FEM-DBCI for the Solution of Open-Boundary Low-Frequency Problems

This paper describes a particular use of the hybrid FEM-DBCI, for the computation of low-frequency electromagnetic fields in open-boundary domains. Once the unbounded free space enclosing the system has been truncated, the FEM is applied to the bounded domain thus obtained, assuming an unknown Dirichlet condition on the truncation boundary. An integral equation is used to express this boundary condition in which the integration surface is selected in the middle of the most external layer of finite elements, very close to the truncation boundary, so that the integral equation becomes quasi-singular. The method is described for the computation of electrostatic fields in 3D and of eddy currents in 2D, but it is also applicable to the solution of other kinds of electromagnetic problems. Comparisons are made with other methods, concluding that FEM-DBCI is competitive with the well-known FEM-BEM and coordinate transformations for what concerns accuracy and computing time.

Electrostatic Field Feature Selection Technique for Breakdown Voltage Prediction of Sphere Gaps Using Support Vector Regression

This article proposes a methodology for air gap breakdown voltage (BV) prediction based on support vector regression (SVR), taking various features extracted from the electrostatic field calculation results as input variables. The genetic algorithm (GA) is applied for feature selection to improve the performance of the SVR model. A case study on sphere gap BV prediction is reported to demonstrate the validity of the proposed technique. This study provides a reference for dielectric strength prediction by artificial intelligence algorithms, thus to guide the optimal design of air insulation structures.

A simple dipole approach for the calculation of electrostatic field and onset corona voltage in wires-to-cylinders electrode configurations

This paper presents a semi-analytical approach for calculating the potential and electric field in a system of several equipotential groups of infinitely long parallel cylindrical conductors. The proposed method is a simplification of the successive dipole simulation method, presented earlier, taking into account the equality of potentials in each group of conductors with given potentials. This method was applied to calculate the electric field in the gap between W wires and W + 1 cylinders of a bipolar conductor system and used only W (W + 1) unknown dipole charges instead of W (2W + 1) in the original version of the successive dipole simulation method. The corona onset voltages were estimated in the conductor systems with W = 1 ÷ 33. The values of the electric field around the thin wires were accurate already in the first stage of the method. The estimations of the corona onset voltages for various discharge gaps were compared with the experimental values. The advantages of this formulation of the successive dipole simulation method are a simpler, clearer, and faster algorithm.

Electrostatic Field Calculation and Structure Optimization of New Shield Ring of 1000 kV Nan-Jing Loop Transmission Line

Considering the frequent breakage of the hard jumper shield ring in the strain tower of ultra-high voltage alternating current 1000 kV Nan-Jing Transmission Line, the theoretical and experimental studies on new shield ring were carried out in terms of mechanical properties; however, due to the structural changes of shield ring, the field characteristics should be calculated and analyzed. In accordance with the theory that there is no electric field in a metal conductor under electrostatic equilibrium, if there is any metal conductor in the 3D model of the computational domain, there will be no need to subdivide the metal conductor. In this paper, a 3D model load applying method with metal conductors was proposed to calculate the field intensity of Tuned mass damper (TMD) shield ring after improving the mechanical properties of the strain tower, which saved the total number of mesh subdivisions by 48.02%, reduced the computational time by 76.47%, and increased the computational efficiency of 3D numerical electric field. The calculation results validated the correctness and effectiveness of this method. The new TMD shield ring with the field intensity meeting the relevant requirements was adopted in 1000 kV Nan-Jing Loop Transmission Line in December 2016, which has been operating in good condition so far.

Simulation of voltage/current waveforms and contact area of pulsed surface discharge on water

Propagation of a surface discharge on water is evaluated using simulation results of the voltage/current waveforms and discharge contact area. Voltage/current waveforms are calculated using an exponential function which assumes the resistance of water decreases with increasing discharge contact area. A conductive disk having a given potential is used to model the discharge contact area and the temporal variation of the radius of the disk is discussed as the discharge propagation. The calculation in the current field is replaced by a calculation of the electrostatic field using the similarity between current and electrostatic fields. The calculation of the electrostatic field is conducted by a charge simulation method. The discharge phenomena are classified into two stages which are the breakdown of needle-to-water gap and the surface discharge propagation on water. The electrostatic field calculation at needle-to-water gap is performed to determine the initial discharge contact area. Expansion of the contact area in the creepage direction, is evaluated by the electric field calculation at the edge of the conductive disk. The expansion terminates when the field becomes lower than 26 kV/cm. The velocity of the expansion increases with the applied voltage. The maximum contact radius increases with decreasing conductivity of water under the same applied voltage. The tendency of simulation results of the expansion of the contact area are consistent with the previous observation results of the discharge propagation.

Electrostatic Field Calculations for Liquid Nitrogen Gaps Assuming a Decisive Field Factor

Volume effect on breakdown voltage is well known in high voltage engineering. The breakdown voltage behavior of liquid nitrogen depending on a high field volume had been quantitatively described for gap lengths up to 20 mm. Breakdown curves for longer gap lengths up to 96 mm derived from measurements with a facility “Fatelini 2” show oscillations and partly low withstand voltages. Electrostatic field calculation for such long gaps shows remarkable high field volume differences between a model for ideal sphere and models including fixation rods. Calculation for the used setup does not show monotonically increasing high field volume depending on gap length but a maximum around 60 mm which can explain the special breakdown behavior in a “mid range” gap length. Further high field calculations were done for not yet used setups in order to make considerations, e.g. for the influence of cryostat material or diameter.

A Cartesian Grid Method for Modeling Charge Distribution on Interfaces via Augmented Technique

In the electrostatic field computations, second-order elliptic interface problems with nonhomogeneous interface jump conditions need to be solved. In realistic applications, often the total electric quantity on the interface is given. However, the charge distribution on the interface corresponding to the nonhomogeneous interface jump condition is unknown. This paper proposes a Cartesian grid method for solving the interface problem with the given total electric quantity on the interface. The proposed method employs both the immersed finite element with the nonhomogeneous interface jump condition and the augmented technique. Numerical experiments are presented to show the accuracy and efficiency of the proposed method.

Electroinduction disk sensor of electric field strength

Measurement of the level of electric fields exposure to the technical and biological objects for a long time is an urgent task. To solve this problem, the required electric field sensors with specified metrological characteristics. The aim of the study is the establishment of theoretical assumptions for the calculation of the flat electric field sensors. It is proved that the accuracy of the sensor does not exceed 3% in the spatial range 0<a <0.2 and in the entire spatial range of measurement is negative. Using the methods of calculation of electrostatic fields, this article examines single-axis electromotive disk sensor radius R, and the estimation errors caused by the inhomogeneity of the field. The maximum of this error is 3% in the spatial range from 0 to 5R to the source field that allows you to design better quality sensors used in different measuring systems of wide application.

A Parallel Implementation of the Correction Function Method for Poisson’s Equation With Immersed Surface Charges

In this paper, a novel graphics-processing unit (GPU) implementation of the recently proposed correction function method (CFM) is presented, for the finite-difference solution of Poisson problems with surface-charge distributions. The CFM is a robust and versatile method most notable for its immersed treatment of interface problems of any geometry, to an arbitrary order of accuracy. Given the well-known interface jump conditions associated with the electric scalar potential, the CFM is here shown to be immediately applicable to the computation of electrostatic fields, in the presence of curved surface-charge distributions. Moreover, an in-depth analysis of the CFM algorithm is presented, in which performance bottlenecks are investigated and significant potential for parallelizability is identified. The resulting parallel CFM algorithm is then implemented using NVIDIA's compute unified device architecture GPU language, yielding a significant increase in performance.

A compact finite scheme for derivatives calculation of electrostatic field in image tube

In this paper, an eighth order combined compact finite difference scheme was presented. Through Fourier analysis and numerical tests, one can find that the scheme has spectral-like resolution, and proved to be an ideal class of schemes for the calculation of high order derivatives calculation of electrostatic field in image tube.

Detailed 3D Simulation of the GEM-based detector

The operation of Micro Pattern Gaseous Detectors (MPGDs) has often suffered from effects such as distortion of the electric field due to space charge, despite their widespread use in particle-physics and nuclear-physics experiments, astro-particle research, medical imaging, material science etc. To keep distortions due to space-charge at a manageable level, a lower ion feedback is required while maintaining substantial detector gain and good resolution. Thus, a proper optimization of the detector geometry, field configuration and gas mixtures are required to have a higher electron transparency and lower ion backflow. In our work, Garfield simulation framework has been adopted as a tool to evaluate the fundamental features of Gas Electron Multiplier (GEM). Our study begins with the computation of electrostatic field and its variation with different geometrical and electrical parameters using the neBEM toolkit. Different efficient algorithms have been implemented to increase the computational efficiency of the field solver. Finally, ion backflow and electron transparency of single and quadruple GEMs with different geometry and field configurations suitable for the ALICE-TPC, have been studied.

Euler-Lagrangian Model of Particle Motion and Deposition Effects in Electro-Static Fields based on OpenFoam

In order to study the powder coating process of metal substrates, a comprehensive, numerical 3D Eulerian-LaGrangian model, featuring two particle sub-models, has been developed. The model considers the effects of electro-static, fluid-dynamic and gravity forces. The code has been implemented in C++ within the open source CFD platform OpenFoam®, is transient in nature with respect to the applied LaGrangian particle implementation and the electro-static field calculation and is stationary regarding fluid-dynamic phenomena. Qualitative validation of the developed solver has already been achieved by comparison to simple coating experiments and will hereby be presented alongside a thorough description of the model itself. Upon combining knowledge of the relevant dimensionless groups and the numerical model, a dimensionless chart, representing all possible states of coating, was populated with comprehensive, exemplary cases, which are shown here as well.

Investigation on emission characteristics of metal-ceramic cathode applied to industrial X-ray diode.

The industrial x-ray diode with high impedance configuration is usually adopted to generate repetitive x-ray, but its performance would be worsened due to lower electric field on the cathode of diode when a voltage of several hundreds of kV is applied. To improve its performance, a novel metal-ceramic cathode is proposed in this paper. Key factors (width, relative permittivity of ceramic, and so on) affecting electric field distribution on triple points are analyzed by electrostatic field calculation program, so as to optimize the design of this novel cathode. Experiments are done to study the characteristics including emission current of cathode, diode voltage duration, diode mean dynamic impedance, and diode impedance drop velocity within diode power duration. The results show that metal-ceramic cathode could improve diode performance by enhancing emission current and stabling impedance; the impedance drop velocity of diode with spoke-shaped metal-ceramic cathode was reduced to -5 Ω ns(-1) within diode power duration, comparing to -15 Ω ns(-1) with metal foil cathode.

An increase in the order of spatiotemporal focusing in the time-of-flight mass spectrometer with nonuniform field in the ion-acceleration regions

An algorithm for the calculation of electrostatic field in an arbitrary region of acceleration in the mass reflector using the criterion of an increase in the spatiotemporal focusing is presented. Nonuniform accelerating field providing spatiotemporal focusing of the third and fourth orders in the presence of uniform field in the reflector is calculated for a mass reflector with ionization on the surface of target. The effect of the size of input window of detector on the resolution in the presence of nonuniform field in (i) ion source and (ii) ion source and reflector is considered.