Simulation Results Of Electric Field Research Articles

Three-Dimensional Transient Electric Field Characteristics of High Pressure Electrode Boilers

An uneven electric field during the operation of an electrode boiler will lead to the emergence of a high field strength area and low field strength area in the furnace, which will endanger the safe and reliable operation and heating efficiency of the electrode boiler. A numerical study of three-dimensional transient electric field distribution characteristics in a 10 kV high-voltage electrode boiler was carried out. The distribution characteristics of the global electric field of the electrode boiler under the nominal voltage of 10 kV were studied, and the distribution law of the electric field of the electrode boiler under poor power quality, such as different bus voltage and three-phase voltage imbalance, was explored. The results show that the electric field distribution characteristics of the three-phase transient are more obvious in the section closer to the electrode disc, and the electric field distribution is the most uniform in the section that is 1.4 m away from the furnace water. In the case of poor power quality, such as different bus voltage and three-phase voltage imbalance, the points of the maximum electric field intensity of the four surfaces change periodically with time, and the greater the bus voltage fluctuation, the more severe the impact on the transient electric field. The three-phase voltage imbalance will shift the peak value of the electric field intensity. The decrease or offset of electric field intensity in the electrode boiler caused by poor power quality will directly affect its heating efficiency. The electric field simulation results have a specific reference value for improving the internal electric field distribution and on-site operation and maintenance of the electrode boiler.

Quaternary nanoparticle array antenna for graphene/silicon near-infrared detector

Infrared imaging chips are crucial for a broad range of military, medicine and biology applications. Although silicon detectors’ on-chip integration technology is matured, their low absorption in near-infrared light results in poor infrared photocurrent response. To increase the photodetector absorption efficiency, antenna-like metal nanoparticles have been widely adopted due to their plasmon resonance effects. Oligomer nanoparticles, including quaternary nanoparticles, exhibit plasmon resonance effects that localize and enhance the light field in a sub-wavelength range. Furthermore, they can interfere with each other to achieve Fano resonance and bound state in continuity, resulting in a stronger localization and enhancement of the electromagnetic field. In this study an array of gold quaternary nanoparticle oligomers is used as the antenna for a graphene/SOI (with 1 μm silicon) heterojunction near-infrared detector. Each oligomer consists of four gold squares, each with a size of 250 nm, forming two pairs of dipoles similar to the orbital hybridization of hydrogen atoms. This thus results in a multi-body coupling structure with bonding state and anti-bonding state. The antenna array parameters, such as the periodic constant, gap between nanoparticles, and angle (<i>θ</i>) between the oligomers, are meticulously adjusted. The optimized device is characterized by using photocurrent and photocurrent mapping, achieving a 2-fold enhancement in photoresponsivity with the maximum value at <i>θ</i> ~ 40°. Notably, a consistent dip in photocurrents is observed for different periods or gap arrays when the angle theta is 20°. The simulation is conducted by using finite-difference time-domain (FDTD), revealing the emergence of Fano-like resonance in the transmittance spectra of the array at approximately 850 nm. The interference caused by the strongly coupling system to the plane coupled leakage field and the nanoparticle plasmon mode results in the formation of a new discrete leakage mode, i.e. the Fano-like resonance. The antenna helps to concentrate and emit the light field energy directionally to the detector, while there is a trade-off between the loss caused by nanoparticles absorption and the leakage energy. The photocurrent reaches a minimal point at a theta angle of 20° angle. At this point, the energy is localized in the oligomers, and the metal absorption loss weakens the plasmon enhancement effect. These findings are further supported by the simulation results of electric field and Poynting vector distribution. These findings indicate an important and promising way to enhance the photo detection efficiency via nanostructured plasmonic antenna.

High-throughput Fabrication of Chitosan/Poly(ethylene oxide) Nanofibers by Modified Free Surface Electrospinning

It is very difficult to electrospin pure chitosan (CS) due to the repulsive forces between its ionic groups produced in the electrospinning process, resulting in the formation of nanofibers by blending CS with other natural or synthetic polymers for electrospinning. In this research work, a high-throughput fabrication of CS/poly(ethylene oxide) (PEO) nanofibers were obtained using a modified free surface electrospinning (MFSE), which contained a titanium solution reservoir with thick smooth edges. Effects of the concentrations of acetic acid (AA), CS and PEO on the conductivity and viscosity of spinning solutions as well as the morphology, crystallinity and yield of CS/PEO nanofibers were investigated. And the fabrication mechanism of MFSE was studied by simulating the electric field distribution using Maxwell 3D due to the importance of electric field distribution in the spinning process. The simulation results of electric field were in keeping with the experimental data and indicated the MFSE could produce a lot of high-quality CS/PEO nanofibers.

Research on fuze microswitch based on corona discharge effect

Abnormal voltages such as electrostatic, constant current, and strong electromagnetic signals can erroneously trigger operation of MEMS pyrotechnics and control systems in a fuze, which may result in casualties. This study designs a solid-state micro-scale switch by combining the corona gas discharge theory of asymmetric electric fields and Peek’s Law. The MEMS switch can be transferred from “off” to “on” through the gas breakdown between the corona electrodes. In the model, one of the two electrodes is spherical and the other flat, so a non-uniform electric field is formed around the electrodes. The theoretical work is as follows. First, the relation among the radius of curvature of the spherical electrode, the discharge gap, and the air breakdown voltage is obtained; to meet the low voltage (30–60 V) required to drive the MEMS switch, the radius of curvature of the spherical electrode needs to be 10–50 μm and the discharge gap between the two electrodes needs to be 9–11 μm. Second, the optimal ratio ε is introduced to parameterize the model. Finally, the corona discharge structural parameters are determined by comparing the theoretical and electric field simulation results. The switch is then fabricated via MEMS processing. A hardware test platform is built and the performing chip tested. It is found that when the electrode gap is 9 μm, the electrostatic voltage is at least 37.3 V, with an error of 2.6% between the actual and theoretical air breakdown voltages. When the electrode gap is 11 μm, the electrostatic voltage is at least 42.3 V, with an error of 10.5% between the actual and theoretical air breakdown voltages. Both cases meet the design requirements.

High-throughput free surface electrospinning using solution reservoirs with different radii and its preparation mechanism study

To solve the problems of low production, needle blockage, and Taylor cone stability, a self-made free surface electrospinning (FSE), namely spherical section FSE (SSFSE), is developed to obtain high-throughput production of nanofibers, which can use solution reservoirs with different radii. The surface morphology of polyacrylonitrile (PAN) nanofibers fabricated using SSFSE is investigated by scanning electron microscopy (SEM). According to the SEM data, response surface methodology (RSM) is used to model and optimize the SSFSE process for evaluating the effect of spinning parameters on the nanofiber diameter, and the established RSM model is applied to determine the optimal spinning parameters. The results reveal that the solution reservoir radius and the applied voltage both have great effects on nanofiber diameter, and nanofibers with the highest quality and yield are achieved using a solution reservoir with a radius of 25mm at 40kV. In addition, the electric field distributions produce in the SSFSE processes with solution reservoirs of different radii are simulated by Maxwell 3D to study the preparation mechanism of the SSFSE device. The electric field simulation results are in keeping with the experimental data and indicate that these five SSFSE devices have the potential to increase the yield, and the device using a solution reservoir with a radius of 25mm provides the highest quality and yield of nanofibers.

Multilayers oil and oil-impregnated pressboard electric field simulation based on space charge

Space charge build-up has been considered as the major issue in the development of HVDC apparatus such as the converter transformer. The existence of space charge can distort the local electric field, which could lead to the degradation and even breakdown of insulation materials. Therefore, it is vital to investigate factors that can affect space charge formation and dissipation characteristics such as the temperature, moisture, ageing, thickness, multi-layered structure and electric fields. This paper mainly focuses on the effect of multilayers and thickness on space charge behaviour of oil and pressboard insulation system. Space charge was measured using the pulsed electroacoustic technique (PEA) method. The space charge results are quantitatively analysed to establish the relationship between interfacial charge density and different pressboard and oil thickness ratios. A new space charge interpolation methodology is utilized to input space charge into the multilayers oil and pressboard model using COMSOL software. The local electric field of multilayers oil-impregnated pressboard and oil could be simulated, with the emphasis on the electric field after the polarity reversal operation. From space charge results, they indicate that the increased thickness of pressboard could prohibit the interfacial charge increase while the increased oil thickness could facilitate interfacial charge increase. Moreover, from the electric field simulation results, they indicate that there is the electric field gradient caused by the space charge for multilayers oil and oil-impregnated pressboard structure. After the polarity reversal, the maximum electric field of the oil caused by the space charge is higher than electric field calculated based on the Maxwell-Wagner theory.

Electric field modeling and analysis of EHV power line using improved calculation method

This paper aims is devoted to modeling and simulation of electric field created by EHV power transmission line of 275 kV using an efficient hybrid methodology, the charge simulation method (CSM) with the Simplex Simulated Annealing (SIMPSA) algorithm in order to find the optimal position and number of fictitious charges used in CSM for an accurate calculation. Various factors that affect the electric field intensity were analyzed; it is found that the influence of the conductor sagging is clearly remarked, the maximum electric field strength at 1 m above the ground level recorded at mid-span point of the power line is 3.09 kV/m, in the proximity of the pylon, the maximum value is significantly reduced to 1.28 kV/m. The configuration type of the transmission line (single or double circuit) and the arrangements of phase conductors on double circuit pylons have a significant effect on the levels of electric field around the transmission line. For a single circuit, the triangular configuration provides the lowest maximum value of electric field. For a double circuit, the inverse phase arrangement (abc-cba) or low-reactance phasing produces the lowest maximum value of electric field. The resulting maximum electric field levels were found below the exposure values set by the ICNIRP and IRPA standards for both occupational and general public. The simulation results of electric field are compared with those obtained from the COMSOL 4.3b Multiphysics software, a fairly good agreement is found.

Electro-optic probe measurements of electric fields in plasmas.

The direct measurements of high-frequency electric fields in a plasma bring about significant advances in the physics and engineering of various waves. We have developed an electro-optic sensor system based on the Pockels effect. Since the signal is transmitted through an optical fiber, the system has high tolerance for electromagnetic noises. To demonstrate its applicability to plasma experiments, we report the first result of measurement of the ion-cyclotron wave excited in the RT-1 magnetosphere device. This study compares the results of experimental field measurements with simulation results of electric fields in plasmas.

Electrical insulation design and evaluation of 60 kV prototype condenser cone bushing for the superconducting equipment

A cryogenic bushing is an essential component to be developed for commercial applications of high voltage (HV) superconducting devices. Due to the steep temperature gradient of the ambient of cryogenic bushing, general gas bushing adopting SF6 gas as an insulating media could not be directly used due to the freezing of SF6 gas. Therefore, condenser type bushing with special material considering cryogenic environment would be better choice for superconducting equipment. Considering these circumstance, we focused on the design of condenser bushing made of fiber reinforced plastic (FRP). In case of the design of the condenser bushing, it is very important to reduce the electric field intensification on the mounted flange part of the cryostat, which is the most vulnerable part of bushings. In this paper, design factors of cryogenic bushing were analyzed, and finally 60kV condenser bushing was fabricated and tested. In order to achieve optimal electric field configuration, the configuration of condenser cone was determined using 2D electric field simulation results. Based on the experimental and the analytical works, 60kV FRP condenser bushing was fabricated. Finally, the fabricated condenser bushing has been tested by applying lightning impulse and AC overvoltage test. From the test results, it was possible to get satisfactory results which confirm the design of cryogenic bushing in cryogenic environment.

Mode analysis of 0.14 THz overmoded surface wave oscillator

Mode analysis of the terahertz wave generated by 0.14 THz overmoded surface wave oscillator (SWO) (overmoded ratio D/ 3) is theoretically accomplished and experimentally validated. At first, longitudinal field-expansion method for mode analysis is established aiming at overmoded Cherenkov devices. Then this method is used to analyze the theoretical mode content of 0.14 THz SWO in detail based on the simulation results of electric field extracted from a 2.5-dimensional PIC (particle-in-cell) code. Results show that the mode content of terahertz wave in different characteristic regions of the oscillator is varied due to the mode conversion, and it is dominated by TM02 and TM03 modes accompanied by a small quantity of TM04 mode at the output. Finally, the energy distribution in the near-field radiation of 0.14 THz SWO is obtained by image-displaying method. The experimental result is reasonably in accord with the theoretical distribution calculated from the mode analysis results under experimental conditions, testifying the feasibility of longitudinal field-expansion method for the mode analysis and the correctness of its results.

Electric Fields Radiated from a Cellular Phone Base Station Antenna Constructed on a Roof-Top

In this article, electric fields radiated from a cellular phone base station antenna constructed on a reinforced concrete roof-top will be investigated by the finite-difference time-domain method, by the near-zone to far-zone transformation technique, and by experimental measurements. From obtained radiation patterns, it is found that the theory of the finite-difference time-domain method implemented with the near-zone to far-zone transformation technique makes a good agreement with the experiment. Simulation results of electric fields radiated from the cellular phone base station antenna are presented and compared, with experimental data measured by a Narda broadband field meter. From electric field distributions on a plane with a height of 1 meter above the roof-top, it is again shown that simulation results calculated by the finite-difference time-domain method make a good agreement with those obtained by measurements. Within 50 meters of the cellular phone base station, the electric fields obtained by measurements and calculations are in the ranges of 0.15–42.47 and 0.24–39.57 V/m, respectively. The maximum electric field strength of 42.47 V/m is less than 45% of the ANSI/IEEE standard for public exposure at 1,795 MHz.

Comparison of experimental measurements and electrostatic simulations of keystone geometry microstrip gas chambers

The developments of MicroStrip Gas Chambers (MSGCs) with non-parallel anodes is a requirement for several proposed pp collider experiments. We have designed and constructed an MSGC with four possible electrode patterns. We report on the measurements of relative gas gain as a function of position along the anodes for each structure and present a comparison of these data with the results of electric field simulations.