Average Electric Field Strength Research Articles

Numerical simulation of flow field coupling with electric field for leakage current particulate matter sensor

With the diesel particulate filter more and more widely applied on engine, the particulate matter (PM) sensor is used to detect malfunctions of diesel particulate filter (DPF) in on board diagnostics (OBD). This paper focused on the new leakage current particulate matter sensor, which has more practical significance. The electric field and flow field were simulated by the COMSOL Multihysics, and the influence rules of sensor electrode parameters on the electric field and flow field were analyzed. The dynamic characteristics of particulate matters with different charges was studied. The simulation results showed that the average electric field strength was higher with higher electrode voltage and larger electrode spacing, which made the motion trend of charged particulate matter to electrodes more obvious. The decrease of electrode spacing or the increase of electrode length made the exhaust flow more stable, and the motion trend of charged particulate matters to electrodes is more obvious with the increase of electrode length. It was concluded that the flow of the exhaust and particulate matter was in good condition when the electrode spacing was 12.5mm, the electrode length is 12.5mm and the electrode voltage ranged between 1000V and 1500V.

7.5 kV, 6.2 GW cm−2 NiO/β-Ga2O3 vertical rectifiers with on–off ratio greater than 1013

Vertical geometry NiO/β n-Ga2O/n+ Ga2O3 heterojunction rectifiers with contact sizes from 50 to 200 μm diameter showed breakdown voltages (VB) up to 7.5 kV for drift region carrier concentration of 8 × 1015 cm−3. This exceeds the unipolar 1D limit for SiC and was achieved without substrate thinning or annealing of the epi layer structure. The power figure-of-merit, VB2/RON, was 6.2 GW cm−2, where RON is the on-state resistance (9.3–14.7 mΩ cm2). The average electric field strength was 7.56 MV/cm, approaching the maximum for β-Ga2O3. The on–off ratio switching from 5 to 0 V was 2 × 1013, while it was 3 × 1010–2 × 1011 switching to 100 V. The turn-on voltage was in the range 1.9–2.1 V for the different contact diameters, while the reverse current density was in the range 2 × 10−8–2 × 10−9 A cm−2 at −100 V. The reverse recovery time was 21 ns, while the forward current density was >100 A/cm2 at 5 V.

Simulation calculation of 3D electric field and natural flashover analysis of ice‐covered silicone rubber insulator

AbstractThe effects of uneven icing, number of icicles, inclination angle of icicle, ice pallets and arc ignition on the electric field are ignored for the two‐dimensional axisymmetric model of ice‐covered insulator. Therefore, a 3D simulation model was developed in this paper. The average electric field strength of air gap (Eav) and maximum field strength of icicle tip (Emax) were determined to characterize the influence of various factors on the electric field distortion degree. The results show that compared with the insulator without ice and with a dry ice, the supply voltage is almost entirely applied to all icicle air gaps for a wet ice‐covered insulator. Eav is independent of icicle diameter and icicle number but increases with the increment of icicle length and icicle inclination angle. Emax raises with the increase of icicle length, icicle number, icicle inclination angle and icicle diameter. As the source of electric field distortion, the ice pallets on the surface of the sheds rise the field strength of air gap. Based on the simulation analysis and natural icing test, the applied voltage is redistributed in the remaining air gaps when an arc occurs in the gap near the high‐voltage terminal, thereby causing the subsequent flashover.

Simple Estimate of the Potential Drop across an Amphiprotic Liquid-Liquid Interface.

Two immiscible liquids in contact with each other can have different internal electrostatic potentials. An associated electric double layer (EDL) therefore exists within each liquid. For amphiprotic liquids, the exchange of protons between the two liquids gives rise to two EDLs, a positively charged EDL in one of the liquids and negatively charged EDL in the other. Using the pKa and pKb of one liquid dissolved in the other and the pH equivalent within each amphiprotic liquid, we can estimate the potential drop, Δφ, between the interior of the two liquids, also known as the Galvani potential or liquid-liquid junction potential. This estimation is independent of surface charge and ionic strength. By using the ionic strength to find the thickness of the EDL, we also estimate the average electric field strength across the interface. For the special case of water (H2O) in contact with an immiscible alcohol (ROH), the potential drop across the interface from the water to the alcohol is Δφ = 2.303VT (pKb + pH - pKw - pH2OR), where VT is the thermal voltage at a given temperature T.

Reduction of Deep Dielectric Charging of Polyimide by Incorporation of Glass Microsphere or Glass Fiber Reinforcement

In outer space’s extreme electron radiation environment, the insulating medium will experience a deep dielectric charging effect. As an excellent insulating medium, polyimide is widely used in spacecraft. In practical use, glass microspheres and glass fibers are often added to increase its mechanical strength. However, the influence of glass microspheres and glass fibers on deep dielectric charging effects has often been ignored in previous studies. Therefore, the work in this article established a 3-D deep dielectric charging model of glass microsphere and glass fiber reinforced polyimide. Using the model, the effects of glass microsphere and glass fiber volume fraction, glass microsphere spacing, glass fiber orientation, and 3-D glass fiber structure were investigated. The results show that the larger the volume fraction of glass fiber or glass microsphere, the more obvious the decrease of polyimide composite media’s average electric field strength. Under the same volume fraction, glass fibers are more favorable to reduce the average electric field strength than glass microspheres. The surface of glass microspheres will form charge accumulation, increasing local maximum electric field intensity, which is greater than the maximum electric field value of pure polyimide under electron radiation. When the spacing of glass microspheres decreases, the degree of electric field distortion increases, but the electric field value decreases when the microspheres contact each other. When the glass fiber orientation is perpendicular to the ground plane, it can better provide the electronic release channel, thereby reducing the deep dielectric charging effect. Using 3-D glass fiber structures can reduce the polyimide’s average electric field value and reduce the maximum local electric field distortion.

Periodical discharge regime transitions under long-term repetitive nanosecond pulses

Intuitively, the nanosecond repetitively pulsed (NRP) corona and spark regimes are sustained successively after onsets due to the high background electron density and/or the surplus heat. In this paper, the NRP discharge unexpectedly swings among different regimes (corona → glow → spark → corona → …) in one pulse train, which is characterized by the periodical spark quench and reestablishment. We have investigated discharge regime instabilities by applying long-term repetitive high-voltage nanosecond pulses of ∼15 ns duration to needle–needle and needle–plane gaps in atmospheric-pressure N2 and N2–O2 mixtures. Pulse-sequence resolved electrical and optical diagnostics have been implemented to capture transition processes. The initial corona gradually grows into glow and then spark ‘pulse-by-pulse’, however, the spark regime was interrupted after a certain number of voltage pulses until the next reestablishment. Narrow pulse width impedes the discharge instability growth within one pulse, and a certain number of voltage pulses are required for the discharge regime transition. The addition of O2 dramatically boosts the duration length of spark regime. A lower output impedance of the power supply induces a higher deposited energy into a spark, however, not necessarily leads to a longer spark regime duration, although both the energy storage and the average electric field strength are approximate. Polarity effects, conventionally diminished in pulse-periodic discharges, are still evident during the discharge regime transition. The periodical discharge regime transition is qualitatively explained based on the plasma–source coupling and the evolution trajectory along the power transfer curve. Feedback mechanisms and residual-conductivity related screening effect in NRP spark discharges are analyzed based on a simplified 0D simulation. The periodical feature is probably caused by the insufficient average deposited energy per unit distance per one pulse cycle. In-depth understandings of ‘non-binary’ regimes (neither corona nor spark) and memory effect mechanisms of NRP discharges could be reached.

A 4 × 4 array multichannel magnetic stimulation system using submillimeter sized planar square spiral coils: The spatial distribution of electromagnetic field

Multi-coil magnetic stimulation has advantages over single-coil magnetic stimulation, such as more accurate targeting and larger stimulation range. In this paper, a 4 × 4 array multichannel magnetic stimulation system based on a submillimeter planar square spiral coil is proposed. The effects of multiple currents with different directions on the electromagnetic field strength and the focusing zone of the array-structured magnetic stimulation system are studied. The spatial distribution characteristics of the electromagnetic field are discussed. In addition, a method is proposed that can predict the spatial distributions of the electric and magnetic fields when currents in different directions are applied to the array-structured magnetic stimulation system. The study results show that in the section of z = 2 μm, the maximum and average magnetic field strengths of the array-structured magnetic stimulation system are 6.39 mT and 2.68 mT, respectively. The maximum and average electric field strengths are 614.7 mV/m and 122.82 mV/m, respectively, where 84.39% of the measured electric field values are greater than 73 mV/m. The average magnetic field strength of the focusing zone, i.e., the zone in between the two coils, is 3.38 mT with a mean square deviation of 0.18. Therefore, the array-structured multi-channel magnetic stimulation system based on a planar square spiral coil can have a small size of 412 μm × 412 μm × 1.7 μm, which helps improving the spatial distribution of electromagnetic field and increase the effectiveness of magnetic stimulation. The main contribution of this paper is a method for designing multichannel micro-magnetic stimulation devices.

Indoor Electromagnetic Radiation Intensity Relationship to Total Energy of Household Appliances

The rapid technological developments in the modern era have led to increased electrical equipment in our daily lives, work, and homes. From this standpoint, the main objective of this study is to evaluate the potential relationship between the intensity of electromagnetic radiation and the total energy of household appliances in the living environment within the building by measuring and analyzing the strength of the electric field and the entire electromagnetic radiation flux density of electrical devices operating at frequencies (5 Hz to 1 kHz). The living room was chosen as a center for measurement at 15 homes in three different environmental regions (urban, suburbs, and open areas). The three measurement methods are (Mode 1: people in a sitting position with electrical appliances on. Mode 2: People in a standing position with electrical appliances on. Mode 3: People are in the upright position while turning off the electrical devices) in the living room. These measurement methods and their results reinforce the importance of this research. The results showed that the average electric field strength measured in Mode 2 is much greater than the two methods, and we also found less electromagnetic radiation in Mode 3 than in the two modes. All results remain within the recommended overall exposure developed by the International Committee for the Prevention of Non-Ionizing Radiation and the International Electrotechnical Commission.

Active heat transfer enhancement by interface-localized liquid dielectrophoresis using interdigitated electrodes

We introduced an active heat transfer control between graphene and water using interdigitated electrodes (IDEs). Oppositely charged co-planer electrodes embedded on a graphene surface created a non-uniform electric field. Resulted interface localized liquid dielectrophoresis (LDEP) perpendicular to surface enhanced the water/graphene coupling and decreased interfacial thermal resistance (ITR) substantially. We correlated the theoretical calculations of average electric field strength near surface with Kapitza values measured at corresponding electrode configurations. We obtained a unified linear variation of Kapitza as a function of average electric strength independent of electrode size and charge. By increasing the electric field strength, we measured up to 96% decrease of Kapitza near electrodes. Since the IDEs generated electric field was only interface localized, it required lower electrode charges than any parallel-plate capacitor systems. We showed that ITR remains effective in heat transfer behavior for systems as big as 100nm such that interface localized electric field can at least increase the heat removal 50% by eliminating the ITR from both graphene/water interfaces of a channel system. By converting hydrophobic few-layer graphene to super-hydrophilic condition with ultra-low Kapitza, current results are important for graphene-based materials considered for the solution of the thermal management problem of current and next generation micro/nano-electronics.

Features of the electron avalanche formation process in a strongly inhomogeneous electric field under high overvoltages

The simulation of the electron avalanche formation process in subnanosecond discharges of high pressure was carried out by means of the Monte-Carlo approach. The discharge gap under consideration was of the configuration “the finger-shaped cathode – the hemispherical anode”. The presence of a conic-shaped microprotrusion on a cathode surface was assumed. Such the electrode configuration provided the strongly inhomogeneous distribution of an electric field. A gas simulated was nitrogen at a pressure of 6 atm. An average electric field strength across the discharge gap was varied from 200 kV/cm up to 400 kV/cm. Microprotrusion height was varied from 0 um up to 30 um. The critical size and formation time of an electron avalanche were determined under various conditions simulated. The threshold electric field strength for electrons to transit into the continuous accelerating regime was calculated for various heights of the microprotrusion. The applicability of the non-self-consistent Monte-Carlo technique for the investigation of the runaway electron kinetics and the correct simulation of the runaway electron beam transport across the discharge gap was shown.

Power Density Measurement within Kaduna North Area of Kaduna State, Nigeria

The measurement of possible presence of radiofrequency (RF) radiations from telecommunication base stations was carried out within Kaduna North Area of Kaduna State, to estimate the maximum level of power density from RF radiations to which the member of the populace within specific radius from the base transceiver station (BTS) are exposed to in relation to the existing guidelines to human exposure. Power density S (µWm-2) measurements were made at interval of 20 m to check the exposure level at public locations from 10 RF antenna sites starting from the foot of each BS to distance (radius) of 100 m using Aaronia Spectran HF-4060 Analyser and the electric field strength E (Vm-1) were calculated. The highest and lowest value obtained from measured mean power densities were 108.27 µWm-2 and 94.74 µWm-2 from a distance of 100 m and 40 m respectively. Also, the highest and lowest average electric field strength were 202.03 (Vm-1) and 188.99 (Vm-1) at 100 m and 40 m respectively. The result obtained, indicates that the measured values were far less than the permissible exposure limits for both workers and the general public as set by the International Commission on Non-ionizing Radiation Protection (ICNIRP). These results shows that the exposure levels in these areas are low and as such will not pose significant health risks to the people living in the study area.

High-voltage pulse bushing with induced voltage distribution between sections

The article presents test results of a sectioned vacuum bushing with induced voltage distribution. The bushing was tested with voltage pulses with amplitudes of 24 and 90 kV. The setting of the voltage along the gradient rings was carried out using a galvanic coupling with the turns of a high-voltage pulse transformer. The presented method has allowed distributing the applied voltage between the sections with a deviation of less than 3.5% from the uniform distribution throughout the entire pulse duration (0.25 μs FWHM). The tests with 90 kV pulses were carried out at a pressure of 10−4 Тоrr. The conical design of the bushing provided a decrease in the average electric field strength in vacuum insulating gaps and a higher rate of the residual atmosphere pumping out, as compared to the traditional cylindrical design of pulse vacuum bushings. The investigated bushing can be used in designs of vacuum electron diodes of pulsed accelerating systems.

Electrospray ionization stability and concentration sensitivity in capillary electrophoresis‐mass spectrometry using a flow‐through microvial interface

Concentration sensitivity is a key performance indicator for analytical techniques including for capillary electrophoresis-mass spectrometry (CE-MS) with electrospray ionization (ESI). In this study, a flow-through microvial interface was used to couple CE with MS and improve the ESI stability and detection sensitivity. By infusing a peptide mixture through the interface into an MS detector at a typical flow rate for CE-MS analysis, the spatial region near the interface was mapped for MS signal intensity. When the sprayer tip was within a 6 × 6.5 × 5mm region in front of the MS inlet, the ESI was stable with no significant loss of signal intensity for ions with m/z 239. Finite element simulations showed that the average electric field strength at the emitter tip did not change significantly with minor changes in emitter tip location. Experiments were conducted with four different mass spectrometer platforms coupled to CE via the flow-through microvial interface. Key performance indicators, that is, limit of detection (LOD) and linearity of calibration curves were measured for nine amino acids and five peptides. Inter- and intraday reproducibility were also tested. The results were shown to be suitable for quantification when internal standards were used.

Экспериментальные исследования таунсендовского разряда с многоострийным катодом на динамической платформе из магнитоуправляемых частиц Fe и Fe-Al

Experimental results of the Townsend discharge in the air gap and atmospheric pressure from a multi-pin cathode based on a dynamic platform of magnetically controlled Fe and Fe-Al particles presented. Dynamic platform method formation from magnetically controlled particles for cathode surface presented. The current-voltage characteristics are obtained for various configurations of the cathode design (with a flat electrode without magnetically controlled particles, with a multi-pin cathode with magnetically controlled Fe or Fe-Al particles), as well as with the presence of a heated spiral in the electrode gap. The use of a multi-pin cathode based on the dynamic platform of magnetically controlled Fe and Fe-Al particles allows to maintain the average electric field strength in the discharge gap and to increase the spark discharge current.

Megacity Aerosol Pollution and Atmospheric Electric Field Disturbances

The relationship between electric field variations and microparticle concentrations in the atmospheric surface layer has been studied using the example of the Moscow region. Synchronous field observations of the electric field strength obtained at two stations (the Moscow Center of Geophysical Monitoring and the Mikhnevo Geophysical Observatory of the Institute of Geosphere Dynamics, Russian Academy of Sciences) have been used. Under megacity conditions, the amplitudes of electric field signals have been found to increase relative to their values outside the region. The ratios of average electric field strengths at the observation stations to the values obtained outside the region have been estimated using the model that is developed. Variations in the electric field have been compared with changes in the concentrations of CO, NOx, SO2, and fine particulate matter (PM2.5 and PM10); the electric field strength and the concentration of microparticles under megacity conditions have been found to be correlated.

Effects of Filler Wire Intervention on Gas Tungsten Arc: Part I - Mechanism

For gas tungsten arc welding (GTAW), the effects of filler wire on the GTA are worth being clarified, which will help deepen the understanding of arc characteristics and in-spire new ideas for the real-time monitoring of weld quality. To this end, this work proposed a novel sensing method of detecting probe voltages (i.e., the voltage signals between a filler wire and tungsten electrode/workpiece). Based on this method, in this first part of the work, a tungsten probe was used to replace the filler wire and to interact with the arc in the specific experiments to elucidate the static and dynamic interaction mechanisms between the GTA and filler wire. The results showed that the filler wire intervention deflects the arc to various degrees and will change the volt-age signals. As a metal conductor, the filler wire will in-crease the arc voltage by increasing the average electric field strength. However, its effects on the different areas of the arc are not always consistent, which makes the change trend of the probe voltages not always the same. Moreover, due to thermal inertia, the probe voltage does not strictly change synchronously with the arc voltage under the dynamic disturbance. This work lays a theoretical foundation for monitoring the stability of the GTAW process.

Comprehensive radiofrequency electromagnetic field measurements and assessments: a city center example.

In this study, radiofrequency electromagnetic field (RF-EMF) measurements were carried out between 2016 and 2018 in one the largest provinces of Turkey; measurement results are compared with the limit values determined by International Commission on Non-Ionizing Radiation Protection (ICNIRP) and Turkey's Information and Communication Technologies Authority (ICTA). In the first stage of a three-phase evaluation, short-term RF-EMF measurements were conducted in 500 locations over a 2-year period. In the second stage, short-term RF-EMF measurement results were analyzed to determine selected locations for long-term RF-EMF measurements to be carried out, including variation of RF-EMF during the day. In the last stage, band selective measurements were taken and the main sources of RF-EMF in the environment were determined. Overall, RF-EMF values do not exceed the limits determined by ICNIRP and ICTA, and they are below levels that threaten public health. In the short-term RF-EMF measurements, RF-EMF levels doubled after fourth generation (4G) systems were introduced. In the long-term RF-EMF measurements, RF-EMF values in the day are 35.4% more than at night. The total measured RF-EMF within the city center is 99.3% base station sourced. Among the six main RF-EMF sources, the devices operating in UMTS2100 band have the most contribution to total RF-EMF of medium with 31.2%. Additionally, we found short-term average electric field strength data are best described by the "exponential distribution," while long-term RF-EMF measurement data is best described by the "Burr distribution."

Uniform shallow trenches termination design for high‐voltage VDMOS transistor

A new uniform shallow trenches termination (ST 2 ) with field plate for high-voltage VDMOS transistor is proposed in this Letter. In ST 2 structure, the electric field near the source is decreased and the depletion region is extended by the field plate, besides, many electric field peaks are introduced in shallow trenches under the field plate and the average electric field strength is increased, both improve the characteristic of the breakdown voltage (BV). Simulation results show the BV of ST 2 VDMOS is 706 V with a termination length L d = 132 μm, which reaches 97% of that of the parallel-plane junction, and the influence of the edge curvature effect is almost entirely eliminated. The ST 2 structure is compatible with conventional CMOS process with only one additional mask and its fabrication is low-cost.

Investigation of tail pipe breakdown incident for 110 kV cable termination and proposal of fault prevention

For cable termination, which is regarded as a key segment of power grid connecting cable lines with other electrical equipments, its insulation parts withstand much higher electric field strength than the average electric field strength of overall cable line. The excessive local electric field strength may result in the appearance of cable termination breakdown fault which can cause serious harm to the power supply reliability of whole transmission line. Historical statistics show that the breakdown location of cable termination is not confined to the vicinity of stress cone. However, the existing researches have not attached enough importance to the breakdown faults at the tail pipe of cable termination. Thus, it is of considerable significance to study the mechanism of breakdown fault at the tail pipe of cable termination. In this paper, a breakdown fault case of cable termination tail pipe on a 110 kV transmission line is investigated. Firstly, the disassembly inspection is applied to cable terminations of this fault line, and the possible breakdown reasons are preliminarily inferred. Then, a three-dimensional electric field simulation model of intact cable termination is established, and the mechanism of creeping discharge and air discharge inside the tail pipe occurred at the initial stage of breakdown fault is explained by this model. Subsequently, by setting defects on cable insulation surface in the simulation model of intact cable termination and varying the size of defects, the process of cable insulation damage inside the tail pipe formed in the initial stage developing into a penetrating cable insulation damage is simulated. Finally, the mechanism of breakdown fault case of cable termination tail pipe is concluded, and some improvement measures for the installation of cable terminations are proposed to reduce the incidence probability of such breakdown fault at the tail pipe of cable termination. The method for analyzing the breakdown fault case of cable termination tail pipe presented in this paper, which combines the disassembly inspection and simulation analysis, can provide reference and suggestions for the investigation and solution in similar cases.

Simulation of high-pressure gas breakdown under conditions of spatially non-uniform initial ionization and temperature

The paper presents the results of numerical simulation of the extended atmospheric pressure discharge in configuration of the tip-to-plane diode. The simulation is based on a hydrodynamic model of a discharge plasma in a pure O2 medium at low average electric field strengths ~ 10 kV·cm−1. It was investigated how initial conditions, such as the presence of a weakly ionized plasma channel or a given temperature profile on the discharge axis, influence on the formation of a discharge structure at the initiation stage.