Magnitude Of Electric Field Research Articles

Toward the Electrostatic Catalysis of Nucleophilic Substitutions: A Surface Chemistry Study of the Menshutkin Reaction.

The catalysis of nonredox reactions by external electric fields is one of the most rapidly expanding areas of chemistry. The Menshutkin reaction, a classic example of bimolecular nucleophilic substitution (SN2), involves the conversion of a tertiary amine to a quaternary ammonium salt by coupling it with an alkyl halide. The reaction barrier of the Menshutkin reaction is theoretically predicted to be highly sensitive to the magnitude and direction of an external electric field experienced by the transition state. In this study, we investigate how near-surface electric fields can drive this prototypical nucleophilic substitution by examining the coupling of a diffusive redox-tagged tertiary amine with an electrode-tethered alkyl bromide under a variable external bias. Our findings reveal a competition between electrostatically assisted reactions, solvent effects, and electrochemically triggered side reactions involving radical intermediates. We estimate that only about 5% of the coupling events are attributable to the external field, while the majority of the reaction products originate from electrochemically generated radical intermediates.

Combination of Boundary Elements and the Ellipsoid Method for Optimizing the Electromagnetic Fields of Overhead Power Lines

ABSTRACTThis study proposes a numerical approach aimed at mitigating electromagnetic field intensities at ground level generated by overhead power lines. The methodology integrates the boundary element method for field evaluation with the ellipsoid method for field optimization, while adhering to critical design and safety constraints. The optimized power line configurations, derived from this integrated approach, achieved significant reductions in both electric and magnetic field magnitudes at ground level without compromising any specified constraints. Moreover, the research findings demonstrate the robustness, efficiency, and practical applicability of the proposed methodology in the design of optimized power lines, offering potential for increased power transfer capability, and decreased environmental and health impacts.

Comprehensive device modeling for AlGaN/GaN based Schottky barrier diodes with beveled p-GaN termination to control electric field

In this article, we have systematically investigated the impact of different structural parameters on the electrical characteristics for AlGaN/GaN based Schottky barrier diodes (SBDs) with beveled p-GaN termination by using TCAD simulation tools. The p-GaN termination can decrease the electric field at the Schottky contact region, thereby suppressing the electrical field magnitude in the Schottky contact region. Then, the breakdown voltage can be enhanced without remarkably sacrificing the forward conduction characteristics. However, in spite of the reduced electric field magnitude in the Schottky contact region, the electric field will possess the peak value at the edge of p-GaN termination. Therefore, the premature breakdown can occur when the electric field therein reaches critical value. Hence, we have comprehensively manipulated the electric field distributions by designing different p-GaN terminations and detailed optimization strategy for the AlGaN/GaN based Schottky barrier diodes has been conducted. Moreover, we find that the strong electric field at the p-GaN termination edge can be reduced by using beveled p-GaN termination, which can extend the electric potential into the bulk GaN region. With the developed defected-related physical models, we also find that the p-GaN termination suppress the capture and release process for the carriers by defects, which improves the dynamic characteristics for the proposed devices.

Vectorial spatial differentiation of optical beams with metal–dielectric multilayers enabled by spin Hall effect of light and resonant reflection zero

We theoretically describe and numerically investigate the operation of “vectorial” optical differentiation of a three-dimensional light beam, which consists in simultaneous computation of two partial derivatives of the incident beam profile with respect to two spatial coordinates in different transverse electric field components. It is implemented upon reflection of the beam from a layered structure by simultaneously utilizing the effect of optical resonance and the spin Hall effect of light. As an example of a layered structure performing this operation, we propose a three-layer metal–dielectric–metal (MDM) structure. We show that by choosing the parameters of the MDM structure, it is possible to achieve the so-called isotropic vectorial differentiation, for which the intensity of the reflected optical beam (squared electric field magnitude) is proportional to the squared absolute value of the gradient of the incident linearly polarized beam. The presented numerical simulation results demonstrate high-quality vectorial differentiation and confirm the developed theoretical description.

Origin of the type III radiation observed near the Sun

Aims. We investigate processes associated with the generation of type III radiation using Parker Solar Probe measurements. Methods. We measured the amplitudes and phase velocities of electric and magnetic fields and their associated plasma density fluctuations. Results. 1. There are slow electrostatic waves near the Langmuir frequency and at as many as six harmonics, the number of which increases with the amplitude of the Langmuir wave. Their electrostatic nature is shown by measurements of the plasma density fluctuations. From these density fluctuations and the electric field magnitude, the k-value of the Langmuir wave is estimated to be 0.14 and kλd = 0.4. Even with the large uncertainty in this quantity (more than a factor of two), the phase velocity of the Langmuir wave was < 10 000 km/s. 2. The electromagnetic wave near the Langmuir frequency has a phase velocity lower than 50 000 km/s. 3. We cannot determine whether there are electromagnetic waves at the harmonics of the Langmuir frequency. If they existed, their magnetic field components would be below the noise level of the measurement. 4. The rapid (less than one millisecond) amplitude variations typical of the Langmuir wave and its harmonics are artifacts resulting from the addition of two waves, one of which has small frequency variations that arise because the wave travels through density irregularities. None of these results are expected in or consistent with the conventional model of the three-wave interaction of two counter-streaming Langmuir waves that coalesce to produce the type III wave. They are consistent with a new model in which electrostatic antenna waves are produced at the harmonics by radiation of the Langmuir wave, after which at least the first harmonic wave evolved through density irregularities such that its wave number decreased and it became the type III radiation.

On the coupled effect of a MIS-based anode and AlGaN-polarized super-junction to reduce the local electric field for AlGaN/GaN Schottky barrier diodes

This work employs advanced physical models with the help of technology computer-aided design tools to systematically design and investigate AlGaN/GaN Schottky barrier diodes (SBDs), focusing on enhancing forward conduction and reverse blocking characteristics. A recessed metal/insulator/III-nitride (MIS) anode is demonstrated to manage electric field distribution. The incorporation of a 1 nm thick Al2O3 layer enables a reduced leakage current and a significant increase in breakdown voltage (BV). Subsequently, tailored field plates (FPs) further improve the BV of the MIS SBD to ∼1650 V but strong electric field magnitude will be found at the edge of the FP. Hence, a MIS SBD with a graded AlGaN barrier layer (MIS-GA SBD) is designed, featuring a gradient decrease in Al content along the [0001] direction. The generation of negative polarization charges within the barrier functions as a super-junction, significantly homogenizing the electric field. As a result, the MIS-GA SBD achieves a remarkable BV exceeding 3500 V, highlighting its strong potential for high-voltage power electronic applications.

Phase-space representation of coherent states generated through SUSY QM for tilted anisotropic Dirac materials

In this paper, we examine the electron interaction within tilted anisotropic Dirac materials when subjected to external electric and magnetic fields possessing translational symmetry. Specifically, we focus on a distinct non-zero electric field magnitude, enabling the decoupling of the differential equation system inherent in the eigenvalue problem. Subsequently, employing supersymmetric quantum mechanics facilitates the determination of eigenstates and eigenvalues corresponding to the Hamiltonian operator. To delve into a semi-classical analysis of the system, we identify a set of coherent states. Finally, we assess the characteristics of these states using fidelity and the phase-space representation through the Wigner function.

Insights on the pulsed-DC powder-pack boriding process: Kinetic, statistic, and electric field dynamics in low and medium temperatures

This study presents novel insights into the Pulsed-DC Powder-pack Boriding (PDCPB) process applied to AISI 1018 steel at low (700 °C) and medium (750–850 °C) temperatures for 1, 2, and 3 h of exposure. The electric field, induced with periodic polarity inversion half-cycles of 10 s under 5–10 A, promoted a constant B+ flux, ensuring a uniform boride layer thickness. The growth of the boride layers was estimated using Dybkov's Chemical Interaction Model (DCIM) and analysis of variance (ANOVA). DCIM established the B activation energies in FeB and Fe2B phases, while ANOVA determined the influence of treatment parameters on the total layer thickness.The results demonstrated a reduction of B activation energies in FeB and Fe2B by up to ∼ 23 % and ∼ 15 %, respectively, compared to conventional powder-pack boriding. These reductions were attributed to electromigration and Joule heating phenomena. ANOVA results indicated that temperature was the most significant parameter (77 %) for total (FeB + Fe2B) layer thickness. At the lowest treatment temperature (700 °C), the highest average boriding media resistance (∼ 3.06 Ω) was measured, and the maximal electric field magnitude (3098 V m−1) was determined through computational analysis.

On EMEC Instability in Bi‐Kappa Distributed Space Plasmas Under the Influence of Parallel DC Electric Field

ABSTRACTEMEC waves driven by kinetic anisotropies and suprathermal particles are expected to play an important role at dissipative scales in the solar wind and planetary magnetospheres. Moreover, the correlation of EMEC waves with electric field magnitude and direction can be a tool to probe the inner magnetosphere. Thus, in this manuscript, we present the study of EMEC waves driven by temperature anisotropy in bi‐Kappa distributed space plasmas in the presence of a parallel DC electric field. The dispersion equation bearing the influence of electric field and suprathermal particles followed by the analytical expressions for wave frequency and wave growth rate is derived. The general dispersion equation is solved numerically to unveil the effect of suprathermal particles, temperature anisotropy, and the magnitude of the electric field on growth rate as well as the domain of unstable wave numbers, and the obtained numerical outcomes are compared with those of the bi‐Maxwellian model. Moreover, the maximum growth rates for EMEC waves have also been obtained.

Impact of Electric Field Magnitude in the Left Dorsolateral Prefrontal Cortex on Changes in Intrinsic Functional Connectivity Using Transcranial Direct Current Stimulation: A Randomized Crossover Study.

This study investigated whether the electric field magnitude (E-field) delivered to the left dorsolateral prefrontal cortex (L-DLPFC) changes resting-state brain activity and the L-DLPFC resting-state functional connectivity (rsFC), given the variability in tDCS response and lack of understanding of how rsFC changes. Twenty-one healthy participants received either 2 mA anodal or sham tDCS targeting the L-DLPFC for 10 min. Brain imaging was conducted before and after stimulation. The fractional amplitude of low-frequency fluctuation (fALFF), reflecting resting brain activity, and the L-DLPFC rsFC were analyzed to investigate the main effect of tDCS, main effect of time, and interaction effects. The E-field was estimated by modeling tDCS-induced individual electric fields and correlated with fALFF and L-DLPFC rsFC. Anodal tDCS increased fALFF in the left rostral middle frontal area and decreased fALFF in the midline frontal area (FWE p < 0.050), whereas sham induced no changes. Overall rsFC decreased after sham (positive and negative connectivity, p = 0.001 and 0.020, respectively), with modest and nonsignificant changes after anodal tDCS (p = 0.063 and 0.069, respectively). No significant differences in local rsFC were observed among the conditions. Correlations were observed between the E-field and rsFC changes in the L-DLPFC (r = 0.385, p = 0.115), left inferior parietal area (r = 0.495, p = 0.037), and right lateral visual area (r = 0.683, p = 0.002). Single-session tDCS induced resting brain activity changes and may help maintain overall rsFC. The E-field in the L-DLPFC is associated with rsFC changes in both proximal and distally connected brain regions to the L-DLPFC.

Electromagnetic wave scattering simulation from precision grinding SiC surface under the influence of suspended micro-particles

ABSTRACT In a precision machining environment, suspended particles in the air have a non-negligible effect on visual roughness measurement results. To address this issue, this paper analyzes the influence of particles on the visual roughness measurement from theoretical derivation and numerical simulation, respectively. Firstly, based on the Lambert-Beer and the light scattering principles, the propagation equation of incident light under the joint action of suspended particles and rough surfaces is derived. Then, a numerical simulation model is designed, and the theoretical equations are verified by simulation experiments. The influence of particle material, particle size (D), particle concentration (N), light wavelength (λ), and SiC surface roughness (R a ) on the average electric field magnitude of the energy-acquisition boundary are analysed based on the simulation experiments. The theoretical derivation shows that the average electric field magnitude of the energy-acquisition boundary is mainly influenced by particle state and rough surface state. The simulation experiment results show that both the particle parameters and the rough surface parameters are consistent with the theoretical derivation. As R a increases, the effect of N on the measurement results decreases. The results reveal the influence mechanism of suspended particles on the visual roughness measurement results and provide a basis for improving visual roughness measurement accuracy.

First-principles study on the microstructure, band structure, mechanical and optical properties of AB-stacked bilayer graphene under constant neutron irradiation with different electric field magnitudes and directions

Carbon-based devices have superior performance and lower power consumption compared to silicon-based devices. However, graphene and related two-dimensional materials are easily influenced by radiation due to their extremely high surface-to-volume ratio. Under constant neutron irradiation conditions, there have been no studies on the effects of the magnitude and direction of an external electric field on various properties of the AB system. This study systematically investigated the neutron irradiation effects on the AB system and the influence of the different electric fields on the properties of the AB system under constant irradiation conditions using the density functional theory and ab initio molecular dynamics method that assigns energy to the primary knock-on atom. The results indicate that under constant neutron irradiation with different electric fields, the changes in system configuration dominate the influence on band structure, while the impact of surface ripples is relatively limited. Reducing the interlayer spacing of the system can make the configuration more stable, which makes the band structure under the electric field more stable. The primary factors influencing the Young's modulus (Y) of the system are changes in the microstructure and the appearance of surface ripples, while the influence of system configuration is relatively limited. Under the irradiation conditions, the electric field can to some extent accurately modulate the band gap of the system. However, it will also correspondingly reduce the system's Y to a certain extent, causing negative impacts on the electrical and thermal conductivity.

A simplified time domain approach to calculate lightning electric fields considering the grounded tower-line-tower (TLT) structure

This study describes a method for calculating electric fields radiated by lightning in the presence of a tower-line-tower (TLT) structure, extending a previous method developed by Rachidi et al. (2002). The method involves using a lattice diagram to analyze current distribution and deriving expressions related to the current distribution along the lightning channel and the TLT structure. Expressions associated with the current distribution along the lightning channel and the TLT structure are derived. The impedances of the towers, the connected overhead grounded wire, and lightning channel were treated as constant values. The subsequent return stroke was analyzed in the paper. The lightning radiated electric fields at an intermediate distance of 15 km considering lightning striking to ground, one single object, and the TLT structure were presented and compared. The directly strike of lightning on a tower plays an important role in the increase of the electric field magnitude, while the neighbored tower and the associated grounded wire contributes to periodical superimpositions on the middle-and-late response of the electric fields. Detail discussion on the influences of the different parameters of the proposed method on the electric fields at 15 km and comparison to the measured data were also presented.

A full-head model to investigate intra and extracochlear electric fields in cochlear implant stimulation

Objective. Despite the widespread use and technical improvement of cochlear implant (CI) devices over past decades, further research into the bioelectric bases of CI stimulation is still needed. Various stimulation modes implemented by different CI manufacturers coexist, but their true clinical benefit remains unclear, probably due to the high inter-subject variability reported, which makes the prediction of CI outcomes and the optimal fitting of stimulation parameters challenging. A highly detailed full-head model that includes a cochlea and an electrode array is developed in this study to emulate intracochlear voltages and extracochlear current pathways through the head in CI stimulation. Approach. Simulations based on the finite element method were conducted under monopolar, bipolar, tripolar (TP), and partial TP modes, as well as for apical, medial, and basal electrodes. Variables simulated included: intracochlear voltages, electric field (EF) decay, electric potentials at the scalp and extracochlear currents through the head. To better understand CI side effects such as facial nerve stimulation, caused by spurious current leakage out from the cochlea, special emphasis is given to the analysis of the EF over the facial nerve. Main results. The model reasonably predicts EF magnitudes and trends previously reported in CI users. New relevant extracochlear current pathways through the head and brain tissues have been identified. Simulated results also show differences in the magnitude and distribution of the EF through different segments of the facial nerve upon different stimulation modes and electrodes, dependent on nerve and bone tissue conductivities. Significance. Full-head models prove useful tools to model intra and extracochlear EFs in CI stimulation. Our findings could prove useful in the design of future experimental studies to contrast FNS mechanisms upon stimulation of different electrodes and CI modes. The full-head model developed is freely available for the CI community for further research and use.

A novel application of artificial intelligence technology for outdoor high-voltage composite insulator

The distribution of the electric field plays a crucial role in evaluating the effectiveness of composite insulators. This research presents an innovative approach for optimizing the design of corona rings, aiming to decrease the electric field intensity in critical areas to satisfactory levels. The investigation examined the correlation among corona ring design variables and the intensity of the electric field close to the energized-end fitting in a 220 kV composite insulator equipped with a corona ring. Using design of experiment methods, the impact of three corona ring design parameters – corona ring diameter (R), ring tube diameter (Dr), and corona ring height (H) – was assessed. A novel nonlinear mathematical objective function was formulated, connecting the electric field magnitude to the structural parameters of the corona ring. Subsequently, the Bat algorithm, a bio-inspired optimization technique, was employed to enhance the initial corona ring design and mitigate the electric field intensity. Finally, the Finite Element Method (FEM) was utilized to simulate and evaluate the voltage distribution and electric field stress. The optimization process resulted in a substantial decrease in the highest electric field magnitude, by 58.6 % compared to the insulator with the threshold value, and 75 % when devoid of a corona ring. Additionally, the research highlighted the significant influence of ring tube thickness on the distribution of the electric field. The combination of experimental design and the Bat algorithm proved to be a powerful tool for optimizing the design of corona rings on transmission line composite insulators, providing precise solutions for optimizing corona discharge problems and enhancing the reliability of power transmission systems.

Designing ITER motional Stark effect line shift (MSE-LS) spectrometers.

As a part of ITER beam aided diagnostics, the design of Motional Stark Effect (MSE) diagnostic observing the emission from the Balmer-α line is underway. The physics of Stark splitting shows that the Stark manifold is polarization dependent, and the energy splitting results in a line shift proportional to the electric field. Due to the challenges of maintaining the calibration of the plasma facing mirrors in ITER, the conventional MSE polarimetry measurement technique is replaced with a spectral approach that is deemed more favorable in the ITER environment. The MSE line shift (LS) diagnostic is designed to quantify the Lorentz electric field magnitude by measuring the Stark manifold using visible spectroscopy. In the presence of large magnetic fields and high energy heating beams of 1MeV, the expected Stark splitting is much larger than in typical devices. The MSE-LS design has unique challenges requiring careful consideration and modeling of its viewing geometry and photon budget. The MSE-LS approach on ITER is promising but has stringent demands on the allowable errors for the statistical and systematic fitting uncertainties. In this study, a full system model and numerical simulations of data for each sightline are completed. For a range of optical transmission fractions, photon noise analysis is conducted to determine the statistical uncertainties. This provides guidance on the spectrometer throughput, dispersion at the detector, optics, and other design choices. A conceptual design of a high throughput spectrometer with a volume phase transmission grating is presented.

Study of MoS2 as an Electric Field Sensor and the Role of Layer Thickness on the Sensitivity.

In this study, we investigate the scope of molybdenum disulfide (MoS2) as an electric field sensor. We show that MoS2 sensors can be used to identify the polarity as well as to detect the magnitude of the electric field. The response of the sensor is recorded as the change in the drain current when the electric field is applied. The sensitivity, defined as the percentage change in the drain current, reveals that it has a linear relation with the magnitude of the electric field. Furthermore, the sensitivity is highly dependent on the layer thickness, with the single-layer device being highly sensitive and the sensitivity decreasing with the thickness. We have also compared the electric field sensitivity of MoS2 devices to that of previously studied graphene devices and found the former to be exceptionally sensitive than the latter for a given electric field magnitude.

Topology optimization of the electrodes in dielectrophoresis-based devices

This paper aims for developing topology optimization methodology to design the shape of electrodes in Dielectrophoresis (DEP)-based devices. The DEP force is due to a non-uniform electric field induced by applied voltages to the electrodes. Shape of the electrodes has the principal effect on the direction and magnitude of the DEP force. In medical therapy microfluidic devices, DEP force is used for cell sorting and cell separation. While the direction and magnitude of the DEP force are desired to be determined and maximized respectively, the magnitude of the electric field should be minimized to avoid damaging cells. Approaching these goals is counter intuitive where the existing electrode designs are basic. Therefore, a detailed finite element model (FEM) is developed for DEP force and electric field to formulate an optimization problem to maximize the DEP force in a particular direction while there is a constraint on electric field's magnitude. Using the developed FEM, explicit formulations for sensitivity analysis are derived to implement a gradient-based topology optimization. The performance of developed methodology is assessed numerically to determine the direction of the DEP force and constraining the electric field and experimentally in a practical case study of particle trapping in a microfluidic channel.

Numerical study of droplet impact on a superheated surface under an electric field based on perfect and leaky dielectric theories

AbstractThis paper investigates the hydrothermal behavior of leaky dielectric and perfect dielectric droplets impacting a superheated wall within a specific range of Weber numbers under an electric field. Through this investigation, we aim to provide a more comprehensive understanding of the dynamics involved in droplet‐superheated surface interactions under electric fields, which can be useful in various applications, such as the design of cooling systems and combustion chambers. The study utilizes the level‐set and ghost fluid techniques to capture the interface accurately. Under an electric field, different behaviors are observed during the impact process, depending on the electrical properties of the droplet. A perfect dielectric droplet experiences a reduction in spreading extent and an increase in contact time. However, no remarkable enhancement in total heat removal occurs in this case. For the leaky dielectric droplet exhibiting prolate deformation at the stationary state, increasing the electric field magnitude results in a slight decrease in the droplet spreading extent, while the droplet contact time and total heat removal from the surface increase. At an electric capillary number of 1.55E − 2 and a Weber number of 25, the enhancement in the contact time and total heat removal is about 43% and 15%, respectively. For the leaky dielectric droplet with oblate deformation at the stationary state, the spreading extent and total heat removal increase, with negligible changes in contact time. At the above‐mentioned electric capillary and Weber numbers, the enhancement in the spreading extent and total heat removal is about 7.5% and 15%, respectively.

Influence of external electric field on molecular microscopic descriptors of non-polar insulating gases

Molecular microscopic descriptors without external electric field are commonly used for the prediction of insulating strength in gaseous medium. However, insulating gases are subjected to external electric field in electrical equipment, and the molecular microscopic descriptors are affected. Therefore, it is necessary to investigate the influence of external electric field on molecular microscopic descriptors. The Gaussian 16 software is employed to calculate the global parameter with the M06-2X functional and the 6–311++G (d, p) basis set. The wavefunction analysis software Multiwfn is used to obtain electrostatic potential parameter. In this paper, three directions of external electric field with magnitude ranging from 0 to 0.03 a.u. have been set to 10 non-polar insulating gas molecules. According to the type of molecular point group, the effect of direction and magnitude of external electric field on the molecular microscopic descriptors has been analyzed. The results indicate that the molecular microscopic descriptors are affected by the direction and magnitude of external electric field. The change rate of microscopic descriptors increases with the increase of external electric field magnitude. And the influence of the direction of external electric field is associated with the molecular symmetry. In conclusion, the effect of direction and magnitude of external electric field is needed to be considered when analyzing the effect of external electric field on molecular microscopic descriptors.