Electric Field Distribution Research Articles

Active control of electromagnetically induced transparency based on vanadium dioxide microstructures

Abstract Electromagnetically induced transparency (EIT) based on metasurfaces has made significant advancements in the past decade. The ability to actively tune EIT is desirable for practical applications, and this has been accomplished by integrating metallic structures with tunable materials. Here, we propose a dynamically tunable EIT using a metasurface composed of vanadium dioxide (VO2) microstructures without additional metallic structures. A single cut wire and a pair of U-Shape split ring microstructures are combined to design the unit cell of the VO2 metasurface, which functions as bright and dark modes, respectively. The destructive interference between these two modes causes an EIT-like resonance at the terahertz band for VO2 in its metallic phase. However, when VO2 transitions into its insulating phase, the EIT resonance gradually vanishes. Theoretical analyses based on the electric field distribution and coupled harmonic oscillator model indicate that the tunable EIT is due to changes in the attenuation rate of two modes. Furthermore, the phase transition of VO2 can generate tunable group delays. The active EIT utilizing VO2 microstructures could be applied in terahertz modulators and tunable slow light devices.

Synergy in Commercial Brass Reinforced Carbon Hybrids Interlayer towards Highly Reversible Zn Anodes

Aqueous Zn‐ion batteries (AZIBs) have served as a promising candidate for next‐generation energy storage applications. Nonetheless, interfacial issues concerning the metallic Zn anode including hydrogen evolution reaction (HER), chemical corrosion, and dendrite growth remain to be carefully addressed. Herein, we present a facile and cost‐effective strategy to implant carbon nanotube (CNT) framework with a commercial brass alloy as the protective interlayer. The conductive network constructed by interconnected CNTs ensures an optimal electric field distribution over the entire electrode surface. The embedded brass alloy not only inhibits the aggregation of CNTs, but also mitigates surface corrosion through its abundance of chemically inert Cu sites. Leveraging the synergy within the carbon hybrids featuring high Zn‐affinity and abundant nucleation sites for Zn2+, lowered energy barriers and promoted redox kinetics for Zn deposition enable highly stabilized and reversible Zn anodes. As a result, symmetric cells demonstrate extended cycling lifespan of 3000 h and 1200 h at 2 mA cm−2 and 5 mA cm−2 for 1 mAh cm−2, respectively. Furthermore, the optimized Zn||MnO2 full cells exhibit impressive cycling stability for 1000 cycles at 2 A g−1.

Ultra-fast terahertz optical switch based on Metal vanadium dioxide

Abstract In current research, the reflection and absorption characteristics of optical switches in optical systems are often limited by the material's response speed and tunable range. We propose a novel metal grating structure with phase-change material to overcome these limitations. This paper proposes a tunable ultrafast terahertz optical switch based on vanadium dioxide (VO₂), composed of a VO₂ layer, a dielectric layer, and metal, with the VO₂ layer located on top of the plasmonic (Au) thin film. The optical performance variations in different states are revealed by analyzing the absorption rate, electric field distribution, and light absorption time of VO₂ before and after phase transition. VO2 exhibits a promising phase transition for actively controlling terahertz waves, with the insulator-to-metal transition used to switch the coupling between surface plasmon modes and normally incident electromagnetic waves on and off. These optical switches enable ultrafast switching, as the VO2 phase transition occurs on the femtosecond timescale. Experimental results indicate that the absorber demonstrates near-perfect absorption peaks, achieving absorption rates as high as 99.99%. The absorption efficiency modulation depth before and after the phase transition can reach 99.92%, allowing the absorber to achieve tunability. The reflectivity of VO2 is about -0.38 dB before the phase transition, and it significantly increases to -23.3 dB after the transition, with a switching ratio of 22.92 dB. This significant reflectivity change is attributed to the VO₂ phase transition, leading it to reflect light signals at high temperatures, preventing their transmission. The electric field diagrams and light absorption time analysis further support this conclusion, demonstrating that VO₂ material can efficiently switch optical signals by modulating temperature. This research offers new approaches for developing high-performance, fast-response terahertz optical switches, with potential applications in future optical communication and signal processing.

Design of wide bandwidth metamaterial for biosensor and wireless application

Abstract We present a new design and study of metamaterial (MTM) structure for wide bandwidth for biosensor and wireless applications. The geometrical parameters were analyzed and optimized for a triple-band operation in the frequency range of 0.1–16 GHz. The propagation characteristics were obtained using Finite element method. The proposed MTM provides negative permittivity at 1.4 GHz and negative permeability in the 9–16 GHz region. The proposed design exhibits left-handed characteristics in L, C, and Ku microwave region’s frequency band. The electric field (E), magnetic field (H), and surface current distribution of the proposed MTM unit cell have been studied at three different resonance frequencies. The proposed MTM design has a wide bandwidth of 2.2 GHz in C-band and a high effective medium ratio (EMR) of 13.37. The performance of the sensor is evaluated for different biomedical samples in the refractive index range of 1.00 to 1.39. The results indicate that the proposed biosensor has a high sensitivity in triple band of microwave region. The present research work can be highly suitable for Wi-Fi and satellite applications due to its overall performance, including wide bandwidth in the C-band, high EMR, and triple band operation.

Design of Bilayer Crescent Chiral Metasurfaces for Enhanced Chiroptical Response

Chiral metasurfaces exploit structural asymmetry to control circular polarized light, presenting new possibilities for the design of optical devices, specifically in the dynamic control of light and enhanced optical sensing fields. This study employed theoretical and computational methods to examine the chiroptical properties of a bilayer crescent chiral metasurface, demonstrating the effect of the angle of rotation on the chiroptical response. We particularly investigated the changes in transmittance, electric field distribution, and circular dichroism (CD) across various rotation angles. The crescent chiral metasurface demonstrated the maximum CD and showed significant control over the CD and electric field distribution across different rotation angles in the near-infrared region. The highest CD value was observed at a 23° rotation angle, where the chiroptical response reached its maximum. In addition, the left circular polarized light showed a stronger intensity of the electric field along the crescent metasurface edge relative to the right circular polarized light, underscoring the significant difference in the intensity and field localization. It was also shown that the configuration with a 2 by 2-unit cell, compared with a single-unit cell, exhibited significantly enhanced CD, thus underlining the importance of the unit cell arrangement in optimizing the chiroptical properties of metasurfaces for advanced photonic applications. These results prove that the 2 by 2 bilayer crescent chiral metasurface can be tailored to a fine degree for specific applications such as improved biosensing, enhanced optical communications, and precise polarization control by optimizing the configuration. The insight presented by this theoretical and computational study will contribute to the broad understanding of chiroptical phenomena as well as pave the way for potential applications in developing advanced optical devices with tuned chiroptical interactions.

Core–Shell Structured BaTiO3@Polyethylene in Low‐Density Polyethylene: Modulation of Dispersion Structure and Improvement of Dielectric Properties

ABSTRACTOrganically modified dielectric filler nanoparticles with core–shell structures have received widespread attention when designing composites with excellent dielectric properties. Herein, the core–shell structured BaTiO3@polyethylene (BT@PE) nanoparticles were prepared and the models of BT@PE filled low‐density polyethylene (LDPE) composites were constructed. The interaction modulated nanoparticle dispersion structure and the effect of the core–shell structured BT@PE on the polarization and breakdown of the composites were studied by molecular dynamics (MD) simulations and finite element analysis (FEA). The results show that BT@PE modulated the interactions between particles, formed a well‐dispersed structure in the LDPE matrix, and optimized the electric field distribution inside the composites. Moreover, due to the existence of microscopic transition layer, the core–shell structured BT@PE increased the interfacial polarization while suppressed the electric field distortion. BT@PE nanoparticles simultaneously enhanced the dielectric constant and breakdown strength of the composites.

Influence of metal particles shape on direct current voltage electric properties of nanofluids

It is widely recognized that the application of nanoparticles has the potential to improve the dielectric properties of transformer oil. Nevertheless, there is a scarcity of studies that have utilized pure nanofluids, and in practical applications, it is inevitable for transformer oil to become contaminated. Therefore, this study conducted tests to investigate how the shape and size of metal contaminants impact the dielectric performance of Fe3O4 nanofluids. The findings from the levitation voltage test indicate that as the size and diameter of the particle increase, the levitation voltage value measured also increases, and conversely. Moreover, a higher concentration of nanoparticles leads to a higher measured levitation voltage value. On the other hand, the breakdown voltage test results demonstrate that larger and sharper particles result in lower measured breakdown voltage values, and vice versa. The simulation outcomes regarding electric field distribution reveal that larger and sharper particles correspond to higher measured electric field values, while the opposite is true for smaller and less sharp particles.

Numerical simulation of surface charge accumulation under negative discharge of different humidities and pressures

The surface discharge phenomenon of polymers severely limits their applications in electrical and electronic devices, especially in complex environments. In this study, a drift-diffusion model based on a hydrodynamic approach was developed to investigate the influence of humidity and gas pressure on the negative surface discharge. The results indicate that the discharge pattern did not change under different humidity conditions. The increased humidity accelerated the formation of discharges and increased the discharge pulse current. In particular, as the humidity increased, tiny pulses occurred at the tail of the first pulse, and the number of tiny pulses increased. The appearance of these tiny pulses changed the surface charge distribution from a “ring-like” distribution to a “spot-like” distribution. Meanwhile, the accumulation of surface charges significantly distorted the spatial electric field distribution and suppressed the electron multiplication stage of the subsequent discharges, thus reducing the current in the Trichel pulse discharge stage. It is precisely because the discharge is stronger under high humidity, resulting in more surface charges accumulating on the surface, which is in keeping with the experimental results. The measured charges at different humidities show a similar distinct spot-like distribution, illustrating a constant pattern of discharge. All these results demonstrated the correctness and applicability of the simulation. The surface discharge under different pressures exhibited some similarities with the case of different humidity levels. As the pressure increased, the number of discharge current pulses and the pulse amplitude decreased, resulting in a decrease in the surface charge density.

Characterization and Simulation of AlGaN Barrier Structure Effects in Normally-off Recessed Gate AlGaN/GaN MISHEMTs

Abstract A high performance of the normally-off recessed gate AlGaN/GaN MISHEMT was successfully demonstrated. This critical recessed gate etch was achieved by atomic layer etching (ALE), which minimizes surface damage and ensures precise control of etch depth in the gate region. Recessed gate MISHEMT with a remaining AlGaN thickness of 5 nm exhibits excellent characteristics, including a maximum drain current (ID,max) of 347 mA/mm, a competition threshold voltage (VTH) of +2.6 V, and a high on/off ratio achieving 109. Furthermore, different remaining thicknesses of AlGaN with recessed gate (2, 3, and 5 nm) MISHEMTs were also studied. The AlGaN layer with a remaining thickness of 5 nm achieved a significantly higher breakdown voltage (BV) of 830 V compared to the AlGaN barrier with remaining thicknesses of 3 nm and 2 nm, which only reached 120 V and 75 V, respectively. The different recessed gate AlGaN remaining electric field distribution results were verified according to technical computer-aided design (TCAD) simulations. This is attributed to the hot electrons effect under the action of the high electric field to promote electrons to overcome potential energy barriers that are injected into a buffer, barrier, or insulating layers and trapped there, degrading off-state breakdown voltage capability.

Dual-band polarization-independent maze-shaped absorber based on graphene for terahertz biomedical sensing

This paper introduces an adjustable metamaterial absorber in the terahertz spectrum with exclusive properties such as resistance to polarization variation. Although this absorber can operate in various applications like chemical and environmental industries, its captivating features in different refractive (RI) make it a good choice in sensing and biomedical applications such as cancer early detection, blood glucose monitoring, and detecting malaria mosquito bites. The structure originally includes four different layers from top to bottom: graphene/ SiO2/Si/Au, respectively. The finite integration technique has been used for simulation. In terms of absorbing parameters, the proposed structure reveals an outstanding absorption of 98.32% at 4.3 THz and 98.49% at 7.35 THz, with an average Q-factor of 8.92, by following simple absorption rules, simulation, and electric field distribution of the suggested structure, which is illustrated through diagrams to consider various parameters such as frequency, sensitivity, and physical mechanism.

Integration of Asymmetric Multi-Path Hollow Structure and Multiple Heterogeneous Interfaces in Fe3O4@C@NiO Nanoprisms Enabling Ultra-Low and Broadband Absorption.

A reasonable construction of hollow structures to obtain high-performance absorbers is widely studied, but it is still a challenge to select suitable materials to improve the low-frequency attenuation performance. Here, the Fe3O4@C@NiO nanoprisms with unique tip shapes, asymmetric multi-path hollow cavity, and core-shell heteroepitaxy structure are designed and synthesized based on anisotropy and intrinsic physical characteristics. Impressively, by changing the load of NiO, the composites achieve strong absorption, broadband, low-frequency absorption: the reflection loss of -55.8 dB and the absorption bandwidth of 9.9 GHz covers both low and high frequency (2.9-6.1 and 11.3-18 GHz). The constructed anisotropic hollow and heterointerface nanoprisms can optimize impedance matching for low-frequency absorption (3.8-7.9 GHz) almost completely covering the 5G band. Especially, the influence of hollow path on the interface polarization and ferromagnetic coupling behavior is revealed through the simulation of electric and magnetic field distribution using the High-Frequency Structure Simulator (HFSS). In addition, HFSS simulation shows that the Radar Cross-Sectional (RCS) value of the absorber at any angle is <-10 dB m2, which meets the complex requirements in practical application. This research paves a new way for the development of efficient low-frequency absorbers based on composition and structure design.

Five-layer gradient structures for improved energy storage performances on the basis of sandwich framework

Abstract High energy storage performances in multilayer nanocomposites are crucial for the advancement of modern electronic and power systems. However, the large dielectric contrast between adjacent layers leads to an uneven electric field distribution, which hampers the potential for further increasing their energy storage performances. Herein, five-layer gradient-structured nanocomposites were designed and fabricated based on previous sandwich framework by introducing transition layers between the outmost insulation layer and the inner polarization layer. Meanwhile, the volume fraction of the polarization layer maintains the same in the two frameworks to minimize adverse effects on polarizations. Experimental and simulation results show that the transition layer is able to effectively reduce dielectric contrast that alleviates electric field distortion and increases two extra interlayer interfaces to prolong breakdown paths, leading to an improved Eb. In addition, Ni(OH)₂ nanosheets could further hinder the breakdown path to suppress leakage current and prevent premature breakdown. As a result, the optimal nanocomposite with x=60 achieves an energy density of 25.9 J/cm³ at 663.6 MV/m, with an efficiency of 80%. This approach provides a promising design for advanced dielectric nanocomposites.&amp;#xD;

A program for modeling the RF wave propagation of ICRF antennas utilizing the finite element method

Abstract Controlled nuclear fusion represents a significant solution for future clean energy, with Ion Cyclotron Range of Frequency (ICRF) heating emerging as one of the most promising technologies for heating the fusion plasma. This study primarily presents a self-developed 2D Ion Cyclotron Resonance Antenna Electromagnetic Field Solver (ICRAEMS) code implemented on the MATLAB platform, which solves the electric field wave equation by using the finite element method, establishing Perfectly Matched Layer (PML) boundary conditions, and post-processing electromagnetic field data. This code can be utilized to facilitate the design and optimization processes of antennas for ICRF heating technology. Furthermore, this study examines the electric field distribution and power spectrum associated with various antenna phases to investigate how different antenna configurations affect electromagnetic field propagation and coupling characteristics.

Anode-Free Zinc-Bromine Batteries Enabled by a Simple Prenucleation Strategy.

The design of anode-free zinc (Zn) batteries with high reversibility at high areal capacity has received significant attention recently, which is quietly challenging yet. Here, a Zn alloyed interface through electroplating is introduced, providing homogeneous Zn prenucleation sites to stabilize subsequent Zn nucleation and plating. By employing Zn-Cu alloy as a module, the complementary simulations and characterizations confirm that the prenucleation alloyed interfaces achieve a homogeneous electric field distribution and greatly enhance the stability of the Zn anode. Accordingly, the Zn//Zn-Cu@Cu half-cells show a long cycle life of over 900h and an average Coulombic efficiency (CE) of 99.8% at an areal capacity of10 mAh cm-2. The assembled anode-free zinc-bromine (Zn-Br2) battery exhibits an attractive stable cycling of 11 000 cycles at 1 mAh cm-2, while over 1000 cycles at the higher areal capacity of 10 mAh cm-2. Excitingly, the Zn-Br2 pouch cell with a capacity of 1000 mAh operates stably over 50 cycles, and achieves successful integration with photovoltaic systems. This anode-free Zn-Br2 batteries constructed through a prenucleation strategy offer new insights into the potential for large-scale energy storage applications.

Inhomogeneous coupling induced quantized distribution of photonic states in Kagome lattices across different Landau levels

Recent progress has demonstrated that synthetic gauge fields can mimic Landau quantization in materials including graphene and lattices for sound and light. However, despite using graphene-like structures with strain-induced textures in prior photonics, it is hard to capture the experimental attainment of distinct photon bound states for various Landau levels. In this work, we introduce an experimental framework for achieving photonic Landau quantization. We present the quantized distribution of photonic states across different Landau levels in a two-dimensional Kagome metal lattice. By introducing inhomogeneous coupling, we implement two kinds of pseudomagnetic field, which quantize spectrums and quantizes distribution of photonic states, respectively. We experimentally observe that the electric field distribution is localized according to the positional attributes of different Landau levels. Our proposed system is more straightforward to implement, and it opens an avenue to explore photonic states at non-zero Landau levels, which are predicted to demonstrate some interesting physical phenomena.

Emerging evidence on the effects of electrode arrangements and other parameters on the application of transcutaneous spinal direct current stimulation.

Transcutaneous spinal direct current stimulation (TSDCS) has the potential to modulate spinal circuits and induce functional changes in humans. Nevertheless, differences across studies on basic parameters used and obtained metrics represent a confounding factor. Computer simulations are instrumental in improving the application of the TSDCS technique. Their findings allow a better interpretation of the tissue conductivities heterogeneity. Emerging findings indicate the electric field is maximal in the segments located between the electrodes and that factors such as the depth of the targeted area, and location of the electrodes on low conductive points, such as the spinous processes, may impact the electric field generated in the spinal cord, with consequences for thoracic versus lumbar or cervical applications. Recently, growing attention has been directed toward the importance of the TSDCS reference electrode's position and its influence on the current field properties at the targeted site. This review highlights the influence of dosage, polarity, and electrode position on the variety of TSDCS results in healthy and some clinical populations. Based on the available evidence, we suggest that although the current dosage appears to have a negligible effect, the variety of electrode montages and configurations of TSDCS can significantly impact the electric field distributions and potentially explain the conflicting results of experimental studies. Future human trials should systematically and thoughtfully evaluate the location of TSDCS electrodes based on the targeted neural structures.

Measurement of the electric field distribution in streamer discharges

Using electric field induced second harmonic generation (E-FISH), we performed direction-resolved absolute electric field measurements on single-channel streamer discharges in 70 mbar (7 kPa) air with 0.2 mm and 2 ns resolutions. In order to obtain the absolute (local) electric field, we developed a deconvolution method taking into account the phase variations of E-FISH. The acquired field distribution shows good agreement with the simulation results under the same conditions, in direction, magnitude, and shape. This is the first time that E-FISH is applied to streamers of this size (&gt;0.5 cm radius), crossing a large gap. Achieving these high resolution electric field measurements benefits further understanding of streamer discharges and enables future use of E-FISH on cylindrically symmetric (transient) electric field distributions. Published by the American Physical Society 2025

3D fluid simulation of the propagation of a nanosecond discharge in air above a liquid surface: investigation of the pattern formation under various conditions and comparison with experiments

Abstract Plasma-liquid interaction remains one of the fundamental processes influencing the various applications. Understanding the influence of external parameters on discharge properties, particularly the discharge dynamic at the liquid surface, is therefore essential. In previous studies, we investigated the impact of voltage polarity, gap distance, and liquid dielectric permittivity and electrical conductivity on nanosecond discharges initiated in air at atmospheric pressure in a pin-to-liquid configuration. Herein, we present a 3D fluid model, improved with stochastic photoionization, to simulate the discharge dynamics under the previously mentioned conditions. The model outputs are compared with the discharge dynamics measured experimentally. For instance, filamentation and the homogeneous emission over solution’s surface measured in positive and negative discharges, respectively, are well reproduced by the simulation. Furthermore, the simulation allowed us to report other plasma properties not accessible experimentally such as the spatio-temporal distributions of electric field (E-field) and electron density. Notably, we observe that the E-field at the front of the negative surface ionization wave (SIW) is nearly four times lower than that of the positive SIW, which may explain the absence of filaments for negative discharges. Furthermore, we find that increasing solution conductivity or gap distance reduce the radial propagation velocity of the circular SIW front and stopping its expansion before a destabilization can occur. The simulation allowed investigating the influence of photoionization strength, and we find that increasing the number of ionizing photons leads to supress the filamentation while keeping the ionization front circular and propagating at high speed.

Coupled Electric‐Thermal Damage Model for Lightning Strikes on Buried Pipeline

ABSTRACTA coupled electrothermal damage theory model for pipelines is proposed to assess the failure behavior of buried pipelines under lightning strikes. This article considers local thermal nonequilibrium (LTNE) conditions in the soil–water porous medium and the nonlinear characteristics of lightning functions. The calculation results show that the proposed theoretical model has better applicability and accuracy compared with previous models. Parametric analysis shows that under lightning conditions of Im = 20 kA and T1/T2 = 1.2/50 μs, the maximum local temperature of the soil around the pipeline can reach 2160 K, leading to pipeline breakdown. Metal pipelines are shown to be more effective in conducting charges, which alters the electric field distribution in the soil and impacts the formation of plasma channels. The half‐peak value of the lightning waveform has a significant impact on pipeline breakdown, and its increase will increase the risk of pipeline breakdown gradually. When considering LTNE conditions, the change in the pipeline surface temperature becomes more pronounced. Under 8/30 and 8/40 μs lightning waveforms, the pipeline surface temperature is approximately 150 and 550 K higher, respectively, compared with the thermal equilibrium conditions. The thermal conductivity and porosity of backfill soil can also affect the thermal damage of lightning‐struck pipelines. With clay filling, the highest pipeline surface temperature can reach 2590 K, while with fine sand and coarse sand, it is 1980 and 1510 K, respectively. The pipeline lightning disaster model proposed in this article has engineering significance for the investigation of pipeline lightning failure and disaster prevention mechanisms.

Synthesis and Characterization of PVC/(Co3O4/CNT)@Au Semiconductor Nanocomposite for Enhanced Medium-Voltage Cable Insulation

Abstract This study presents the synthesis, characterization, and application of a novel PVC/(Co3O4/CNT)@Au nanocomposite for enhanced medium-voltage cable insulation. The nanocomposite was developed by incorporating Co3O4 octahedron nanoparticles, carbon nanotubes (CNTs), and gold nanoparticles (Au) into a polyvinyl chloride matrix. Compared to standard PVC insulation, the nanocomposite exhibited a 3% improvement in relative permittivity (increased from 2.34 to 2.41) and significantly enhanced field uniformity, as evidenced by simulation studies. Fourier-transform infrared spectroscopy, X-ray diffraction, and electron microscopy confirmed the successful integration of nanofillers and highlighted their contributions to the composite’s properties. Optical characterization revealed a direct bandgap of 4.60 eV and an Urbach energy of 0.3674 eV, indicating a wide-bandgap semiconductor with moderate structural disorder. AC conductivity measurements demonstrated frequency-dependent behavior, while dielectric constant and loss analyses suggested the material’s potential for energy storage and insulation applications. The choice of Co3O4 and CNTs was guided by their synergistic impact on charge trapping, field grading, and thermal management, while Au nanoparticles enhanced charge transfer and local electric field distribution. These findings demonstrate the nanocomposite’s promise in addressing the limitations of traditional PVC insulation, offering improved dielectric performance, reliability, and durability for power transmission and distribution systems.&amp;#xD;