Electric Field Distribution Research Articles

Thin film resonant metasurface absorbers using patch-based arrays on liquid crystal polymer substrates for centimeter-wave applications

This paper reports the design and development of thin-film resonant absorbers for narrowband and multiband operation in the frequency regions centered at 10 GHz. The structure of the resonant metasurface absorber (RMA) is based on a liquid crystal polymer (LCP) thin-film spacer with a copper patch array on the front surface and un-patterned copper film on the back surface of the LCP film. The design and simulation works were carried out using full-wave analysis of the RMA characteristics. The copper-based periodic patch array acts as a metasurface. The perfect RMA for a given LCP film thickness can be obtained through impedance optimization by adjustment of the dimensions of the lattice periods. The electric and magnetic field distributions were studied. The resonant film absorber based on a 100 μm thick LCP film has an electrical thickness of λ/300 at 10 GHz. The experimental work was conducted using a narrowband RMA prototype consisting of 11×11 cells. The measured result of the resonant absorption is at 10.1 GHz, which is in close agreement with the design frequency of 10 GHz. For multiband functionality, double- and quad-band film resonant absorbers have been designed based on a coplanar supercell utilizing the superposition of the resonance effect. The LCP film-based absorbers have the potential to be used in EM shielding and sensing applications in centimeter-wave applications.

N-Doped Ti3C2Tx Interfacial Layer Enabling Uniform Zn Deposition along (002) Plane for Stable Aqueous Zinc-Ion Battery.

Aqueous zinc-ion batteries hold great potentials for large-scale grid energy storage. However, the electrode corrosion, hydrogen evolution, and dendrite growth of Zn anode often lead to cell failure. Herein, N groups in Ti3C2Tx (NMXH) are introduced as interfacial layer through hydrothermal treatment of Ti3C2Tx with urea. The experimental analysis and density functional theory calculation indicate that N groups in Ti3C2Tx can homogenize electric field distribution, promote adsorption of Zn2+ on N groups, and strength interactions between N groups and Zn atoms on (002) plane. Thereby, the use of NMXH interfacial layer can effectively suppress the side reactions and realize uniform Zn deposition along the (002) plane. As a consequence, the NMXH─Zn//Zn cell exhibits an ultralow nucleation overpotential (1mA cm-2, 18.9mV) and can stably operate for 1400h at 1mA cm-2 (1 mAh cm-2) and 110h at 40mA cm-2 (1 mAh cm-2). A full battery with V2O5 nanowires as cathode displays a discharge capacity of 219 mAh g-1 (1.0 A g-1), along with a decent rate capability and cyclability. The significant role of N groups reported in this work offers a promising avenue to improve the cycling stability of Zn anodes of aqueous zinc batteries.

High-temperature relaxation and microwave dielectric response of (1-x)BaNd1.76Bi0.24Ti5O14-xBa0.6Sr0.4La4Ti4O15 compounds with adjustable medium-high dielectric constant

Dielectric ceramics in the microwave band are one of the crucial materials for mobile communication technology, and the studying of their phase evolution and defect behavior can help to understand and reduce dielectric loss. In this work, (1-x)BaNd1.76Bi0.24Ti5O14-xBa0.6Sr0.4La4Ti4O15 (x = 0.2, 0.4, 0.6 and 0.8, (1-x)BNT-xBSLT) ceramics were synthesized by solid-state reaction method. X-ray diffraction (XRD) and Raman spectra analysis reveal that tungsten bronze and hexagonal perovskite phases coexist in the ceramics, and BaNd2Ti3O10 is indexed as the main crystalline phase at x = 0.4, 0.6, leading to a deterioration of the microwave dielectric properties. The defect-related relaxation behavior and its effect on microwave dielectric properties were analyzed by dielectric temperature spectrum and thermally stimulated depolarization current (TSDC). The relationship between the dielectric constant and the electric field distribution was solved using the eigenmode of the high frequency structure simulator. In short, the (1-x)BNT-xBSLT ceramics at x = 0.8 exhibit excellent microwave dielectric properties: εr = 47.2, Q×f = 16,800 GHz, and τf = −4.6 ppm/°C. The microwave dielectric response of BNT-BSLT composite ceramics is closely related to the phase composition and defects, which is informative for the development of low dielectric loss ceramics.

The Influence of Relative Position on Ground Potential and Electric Field Based on Interfacial Charge Accumulation in HVDC

AbstractWith the development of high‐voltage direct current (HVDC) engineering around the world, there has been increasing attention to the issue of selecting site for direct current (DC) grounding electrodes since the pollution coming from ground potential and electric field. As previous study result, the distance is closer to the grounding electrode, the influence is greater for ground potential and electric field, as well as vice versa. Through proposing the analysis approach of equivalent interfacial charge accumulating, the article goes beyond this previous general‐conclusion and extracts the relative position conception from the mono‐distance for further studying on weakening their impacts on the environment. In comparison with the previous results, the research finding shows that the movement of relative position is able to achieve the best distribution of ground potential or electric field corresponding to different soil‐layered structure, furthermore, the specific mathematic formula about the best relative position has been derived by the accumulated charge model proposed. Finally, the results have been demonstrated by simulation calculation of the CDEGS software for a practical HVDC project in China, moreover, regarding soil resistivity variation related to the different seasons, the optimized relative position about 13 ~ 24 km has been adopted in the real HVDC grounding project as a suggested site. It reveals that the underlying relative position behind the mono‐distance could be applied to selecting the site of grounding electrode as reference in the future. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Controllable Construction of Aptamer-Modified Fe3O4@SiO2-Au Core-Shell-Satellite Nanocomposites with Surface-Enhanced Raman Scattering and Photothermal Properties and Their Effective Capture, Detection, and Elimination of Staphylococcus aureus.

The early monitoring and inactivation of bacteria are of crucial importance in preventing the further spread of foodborne pathogens. Staphylococcus aureus (S. aureus), a prototypical foodborne pathogen, is widely present in the natural environment and has the capability to trigger a range of diseases at low concentrations. In this work, we designed Fe3O4@SiO2-Au core-shell-satellite nanocomposites (NCs) modified with aptamer for efficient capture, high-sensitivity surface-enhanced Raman scattering (SERS) detection, and photothermal therapy (PTT) against S. aureus. Fe3O4@SiO2-Au NCs with tunable Au nanocrystal nanogaps were prepared. By combining the finite-difference time-domain (FDTD) method and experimental results, we studied the electric field distribution of Fe3O4@SiO2-Au under different Au nanogaps and ultimately obtained the optimal SERS substrate FSA-60. The modification of aptamer on the surfaces of FSA-60 could be used for the specific capture and selective detection of S. aureus, achieving a detection limit of as low as 50 cfu/mL. Furthermore, Apt-FSA-60 possessed excellent photothermal properties, demonstrating the strong photothermal killing ability against S. aureus. Therefore, Apt-FSA-60 is a promising high-sensitivity SERS substrate and efficient photothermal agent and is expected to be widely applied and promoted in future disease prevention and treatment.

Composite electrolyte with self‐inserted structure and all‐trans F conformation provides fast Li+ transport for solid‐state Li metal batteries

AbstractSolid‐state Li metal battery has attracted increasing interests for its potentially high energy density and excellent safety assurance, which is a promising candidate for next generation battery system. However, the low ionic conductivity and Li+ transport number of solid‐state polymer electrolytes limit their practical application. Herein, a composite polymer electrolyte with self‐inserted structure is proposed using the layered double hydroxides (LDHs) as dopant to achieve a fast Li+ transport channel in poly(vinylidene‐co‐trifluoroethylene) [P(VDF‐TrFE)] based polymer electrolyte. In such a composite electrolyte, P(VDF‐TrFE) polymer has an all‐trans conformation, in which all fluorine atoms locate on one side of the polymer chain, providing fast Li+ transport highways. Meanwhile, the LDH can immobilize the anions of Li salts based on the electrostatic interactions, promoting the dissociation of Li salts, thereby enhancing the ionic conductivity (6.4 × 10−4 S cm−1) and Li+ transference number (0.76). The anion immobilization effect can realize uniform electric field distribution at the anode surface and suppress the dendritic Li growth. Moreover, the hydrogen bonding interaction between LDH and polymer chains also endows the composite electrolyte with strong mechanical properties. Thus, at room temperature, the Li || Li symmetric cells can be stably cycled over 1000 h at a current density of 0.2 mA cm−2, and the full cells with LiFePO4 cathode deliver a high capacity retention (>95%) after 200 cycles. This work offers a promising route to construct solid‐state polymer electrolytes with fast Li+ transport.image

Knowledge-assisted differential evolution based non-contact voltage measurement for multiconductor systems in smart grid

Multiconductor systems, such as overhead lines and multicore cables, are widely used in smart grids for their reliable power transmission capabilities. However, measuring the voltage of individual conductors in these systems has been challenging despite their promising applications. This paper proposes a novel framework to address this issue by utilizing a low-cost electric field (EF) sensor array and a knowledge-assisted differential evolution algorithm. The framework involves designing an annular EF sensor array to capture EF information around the multiconductor systems while ensuring its anti-interference capabilities through grounding and balanced electrodes. Furthermore, an optimization problem is formulated to reflect the model accuracy, and a knowledge-assisted differential evolution algorithm is proposed to optimize the voltage values and conductor positions by leveraging knowledge about the conductor positions and EF distribution. The use of this knowledge is expected to generate promising initial solutions for accelerating the optimization process. The proposed framework is experimentally validated, and the results demonstrate the robustness and accuracy of the EF sensor array and algorithm in obtaining the voltage of individual conductors in multiconductor systems.

Effect of liquid surface depression size on discharge characteristics and chemical distribution in the plasma-liquid anode system

Atmospheric pressure plasma-liquid interactions exist in a variety of applications, including wastewater treatment, wound sterilization, and disinfection. In practice, the phenomenon of liquid surface depression will inevitably appear. The applied gas will cause a depression on the liquid surface, which will undoubtedly affect the plasma generation and further affect the application performance. However, the effect of liquid surface deformation on the plasma is still unclear. In this work, numerical models are developed to reveal the mechanism of liquid surface depressions affecting plasma discharge characteristics and the consequential distribution of plasma species, and further study the influence of liquid surface depressions of different sizes generated by different helium flow rates on the plasma. Results show that the liquid surface deformation changes the initial spatial electric field, resulting in the rearrangement of electrons on the liquid surface. The charges deposited on the liquid surface further increase the degree of distortion of the electric field. Moreover, the electric field and electron distribution affected by the liquid surface depression significantly influence the generation and distribution of active species, which determines the practical effectiveness of the relevant applications. This work explores the phenomenon of liquid surface depression, which has been neglected in previous related work, and contributes to further understanding of plasma-liquid interactions, providing better theoretical guidance for related applications and technologies.

Highly sensitive near-field leakage-enhanced optical fiber SPR sensor based on gold nanoarrays modulation

A novel near-field leakage-enhanced optical fiber surface plasmon resonance (NLF-SPR) sensor based on the synergistic sensitization of cuboid gold nanoarrays and WSe2 film is proposed for the first time to our knowledge. The sensor is composed of a side-polished multimode fiber, a continuous gold film, a continuous tungsten selenide (WSe2) film, and well-arranged cuboid gold nanoarrays. The sensor leverages the high carrier mobility characteristic of the WSe2 film, the near-field leakage enhancement arising from the nanoarrays structure, and the localized electric field enhancement property introduced by nanotips to enhance the refractive index sensitivity. In order to optimize the spectral characteristic, the modulation of electric field distribution and spectral characteristic by the structural parameters of gold nanoarrays is investigated through three-dimensional (3D) finite element simulation. Results show that in the refractive index range of 1.3332–1.3432 refractive index unit (RIU), the average sensitivity of the NLF-SPR sensor can reach up to 10108 nm/RIU, and the highest sensitivity can reach up to 14692.46 nm/RIU. The average sensitivity and the highest sensitivity are 1.87 times and 2.56 times higher, respectively, than those of the side-polished fiber SPR sensor with a monolayer gold film. Furthermore, the experimental results demonstrate that the near-field leakage enhancement introduced by gold nanoarrays improves the performance of the fiber SPR sensor, resulting in a 49.3 % increment in sensitivity. The experimental results are in agreement with the trend of the simulation results. Even better performance improvements have been achieved compared to existing methods and a more flexible approach to performance tuning is provided. With the maturity and development of various nanoarray processing techniques such as focused ion beam, electron beam lithography, and nanoimprint lithography, the proposed NLF-SPR sensor has the potential to be fabricated on a large scale and is expected to be widely employed in biomedical, clinical applications, and other fields.

Multi-Physics Simulation and Optimization of Jet Electrodeposition for Ni–Diamond Composite Coatings

This work investigated the influence of current density, plating solution flow rate, and nozzle outlet-to-cathode distance on the properties of Ni–diamond composite coatings. A multi-physics field simulation was employed to analyze the interplay between current density, plating solution flow rate, and nozzle outlet-to-cathode distance on the flow field and electric field distribution. Additionally, particle tracing simulations were incorporated into the model to evaluate the incorporation efficiency of diamond particles during composite electrodeposition. It was found that when the inlet flow rate of the electrolyte was 5 L/min, the distance between the nozzle outlet and the cathode was 3 mm, and the current density was 60 A/dm2, the composite electrodeposited coating had a higher particle content and better uniformity. The simulation results were validated through experimental preparation and performance testing. This combined approach provides valuable insights for optimizing the jet electrodeposition process for Ni–diamond composite coatings with superior properties.

Five narrow bands terahertz metamaterial absorber based on metal and Dirac semi-metal for high sensitivity refractive index sensing

A five narrow bands terahertz metamaterial absorber based on metal and Dirac semi-metal for high sensitivity refractive index sensing is designed in this paper. The absorber is a traditional sandwich structure. And the most remarkable difference is that two hybrid materials (metal and Dirac semi-metal) are used in the top layer. The numerical results show five absorption peaks can be achieved at 5.527, 5.759, 7.247, 9.257 and 10.186 THz, among which the perfect absorption achieve at 5.759, 7.247 and 10.186 THz, respectively. The physical mechanism of the proposed absorber is analyzed qualitatively and quantitatively by electric field distributions and couple-mode theory. In addition, the sensing application of the proposed absorber is also studied. The sensitivity of the sensing band can reach up to 3.89 THz/RIU by computation. Finally, we design a specific application scenario to ensure the accuracy of the absorber in application through calculation. We believe that the absorber we designed will shine brilliantly in the fields of thermal imaging, thermal radiation and photothermal detection.

Multi-factor coupling analysis of electric field distribution in electrochemical machining with electrolyte suction tool

Electrochemical machining (ECM) technology holds significant potential for applications in high accuracy engineering and manufacturing. To confine the electrolyte region during ECM and mitigate the effects of reaction products and heat generation, an electrolyte suction tool has been proposed. However, the complex electric field distribution on the anode surface during the application of pulse voltage, limits the further utilization of ECM with suction tool. A multi-physics simulation model is established to calculate the region of electrolyte confinement by the suction tool, current density distribution within the electrolyte region, and material removal. The model considers the combined effects of polarization and double layer, and all key parameters are calibrated through classical electrochemical testing experiments rather than fitted based on the predicted results. This study elucidates the transient response of current density on the anode surface during the application of pulse voltage. The simulation accuracy is validated by comparing experimental and simulated current waveforms, as well as material removal profiles under different pulse parameters and electrode shapes. This research is of great significance for improving surface precision and controllability of complex structures in ECM with suction tool, promoting its further application in the field of precision machining.

Experimental and model analysis of the thermoelectric characteristics of serial arc in prismatic lithium‐ion batteries

AbstractAiming at the electrical safety problems of lithium‐ion battery system due to series arc fault, a finite element simulation model of square battery under series arc fault is established based on the magnetohydro‐dynamic equations. The arc voltages at different electrode spacings are analysed, and the electric field distribution, magnetic field distribution, arc temperature and flow velocity around the arc are investigated to determine the maximum values and locations of the electric field strength, magnetic density, arc temperature and flow velocity at the time of the arc fault. Then, on the basis of the series arc experimental platform, determine the value of the arc starting voltage and the critical power supply voltage that produces a stable arc, analyse the evolution of the arc burning time with different loop currents, the evolution of the arc of the separation gap, and then summarise the effect of the disaster on the battery. Finally, the errors of simulation and experimental arc voltage and battery surface temperature are analysed to verify the accuracy of the model.

A fast numerical method for calculating SPND space charge effect at steady state

To address the issue of low efficiency and long computation times in calculating the space charge effect in Self-Powered Neutron Detectors (SPNDs), we developed a fast and efficient numerical method to calculate the steady-state electric fields in SPND insulators. Previous calculations have shown that even when the electric field in the SPND insulator reaches 1 GV/m, its effect on electron transport is negligible. Therefore, we assume that the electric field has a negligible effect on electron transport. Based on this assumption, we developed a one-step numerical method for calculating the steady-state electric field in the insulator. This fast method is based on the charge conservation equation in equilibrium, thus requiring only a single charge deposition result without an electric field to obtain the distribution of the electric field under steady-state conditions. We validated our method by comparing it with precise iterative calculation results and experiments. The computational results indicate that, for three typical experimental scenarios, the fast method only takes up to one percent, or even less, of the time required by the iterative method. At the same time, the Mean Relative Error (MRE) in the electric field distribution between the fast method and iterative calculations are 1.48%, 0.31%, and 5.12%, respectively; whereas the relative errors in sensitivity calculations based on the electric field compared to iterative calculations are all less than 2%. Therefore, the fast method can significantly reduce computation time and ensure sufficient accuracy of steady state electric field distribution when the electric field is less than 1 GV/m. The introduction of this method has made it possible to conduct space charge effect assessments and precise sensitivity calculations for the placement of detectors throughout the entire reactor core.

Photoluminescence Spectroscopy Sheds New Light on Silicon Microchip Functional Properties.

In this study, we demonstrate that photoluminescence spectroscopy probing local interaction and dynamics at the fundamental level is a versatile tool for testing and evaluation of semiconducting materials as well as microscale chips based on them. Monocrystalline silicon, which is still an undisputed leader among semiconductors in microelectronics, exhibits very low photoluminescence emission additionally shielded by the metallization and passivating layers at the integrated circuit level. To unleash the full potential of photoluminescence spectroscopy for advanced testing and evaluation of the functional properties of the silicon microchips, new essential conceptually built approaches are required that overcome this problem. Here, we report on the first fundamental research-based application of a potentiometric dye to sense the electric field of operational silicon chips. Furthermore, we demonstrate high sensitivity of crystalline silicon phonon-assisted photoluminescence to local temperature in the 27-64 °C range. Our results show that sensing and mapping of thermal and electric field distributions using photoluminescence can enable precision testing of the structure, function, operation, and security, not only at the component level but also at the level of the entire integrated circuit.

Understanding the Reversible Transition of Unipolar and Bipolar Resistive Switching Characteristics in Solution-Derived Nanocrystalline Au-Co3O4 Thin-Film Memristors.

Nanocrystalline Au-Co3O4 thin films were fabricated through a facile solution-processing method, and voltage-polarity-dependent resistive switching (RS) characteristics including variability of Set/Reset voltages, stability of cycling endurance, and carriers transport mechanism were studied in the Pt/Au-Co3O4/Pt memory devices. The switching voltages of the Set and Reset processes in the bipolar RS memristors exhibited lower variability as compared to the unipolar resistance switching devices. Moreover, the switching performance of cycle-to-cycle endurance in bipolar mode had a smaller fluctuation than those of unipolar switching behavior. Based on the current-voltage curve fitting analysis, it was found that Ohmic-conduction behaviors dominated the carriers transport of low-resistance state regardless of unipolar or bipolar switching behaviors. The carrier transport of high resistance state was governed following Poole-Frenkel emission and Schottky emission mechanisms in the unipolar and bipolar switching modes, respectively. The physical switching mechanism of Pt/Au-Co3O4/Pt memory devices was proposed using the model by means of growth and disruption of conducting filaments, involved in memory effects of thermochemical mechanism and valence change mechanism in the unipolar and bipolar RS, respectively. The proposed model following the finite element method revealed the roles of electrical field distribution and temperature gradient to further clarify the RS mechanism. Our results open a door for understanding and optimizing oxide-based thin-film resistance switching memory devices.

High-performance terahertz microfluidic sensors based on Fabry–Perot resonance

The Fabry–Perot resonance within a microfluidic channel plays a crucial role in enhancing electromagnetic field strength, facilitating intensified interactions between terahertz waves and samples. In this paper, we introduce 2 THz microfluidic sensors based on Fabry–Perot resonance, each exhibiting dual resonant peaks for non-destructive detection. The first sensor features a periodic arrangement of three “I-type” structures, generating resonant peaks within the frequency range of 0.2–1.2 THz. These peaks correspond to absorption rates of 99.17 % and 99.51 %, with sensitivities of 100 GHz/RIU and 193 GHz/RIU, respectively. The second sensor also produces resonant peaks in the terahertz range, with absorption rates of 99.88 % and 99.94 % and sensitivities of 159 GHz/RIU and 226 GHz/RIU. After elucidating the physical mechanisms of both absorbers by analyzing the electric field and surface current distributions, we tested the dielectric constants of edible oils using the first sensor and evaluated the polarization insensitivity of the second sensor. These findings position the proposed sensors as versatile tools for biological detection and label-free detection even in trace amounts.

A Novel 4H-SiC SGT MOSFET with Improved P+ Shielding Region and Integrated Schottky Barrier Diode.

A silicon carbide (SiC) SGT MOSFET featuring a ""-shaped P+ shielding region (PSR), named SPDT-MOS, is proposed in this article. The improved PSR is introduced as a replacement for the source trench to enhance the forward performance of the device. Its improvement consists of two parts. One is to optimize the electric field distribution of the device, and the other is to expand the current conduction path. Based on the improved PSR and grounded split gate (SG), the device remarkably improves the conduction characteristics, gate oxide reliability, and frequency response. Moreover, the integrated sidewall Schottky barrier diode (SBD) prevents the inherent body diode from being activated and improves the reverse recovery characteristics. As a result, the gate-drain capacitance, gate charge, and reverse recovery charge (Qrr) of the SPDT-MOS are 81.2%, 41.2%, and 90.71% lower than those of the DTMOS, respectively. Compared to the double shielding (DS-MOS), the SPDT-MOS exhibits a 20% reduction in on-resistance and an 8.1% increase in breakdown voltage.

Breakdown voltage enhancement and specific on-resistance reduction in depletion-mode GaN HEMTs by co-modulating electric field

In this letter, a depletion-mode GaN high electron mobility transistors (GaN HEMTs) with high breakdown voltage and low on-resistance are designed and experimentally demonstrated. It combines the gate field plate and partial unintentionally doped GaN (u-GaN) cap layer (gate field plate and partial u-GaN cap HEMTs: GPU-HEMTs) to co-modulate the surface electric field distribution, which results in the electric field peak being far away from the gate edge, thus improving the breakdown voltage and decreasing the on-resistance. The optimized GPU-HEMTs exhibit a larger output current (I DS) of 495 mA mm−1 and a correspondingly smaller specific on-resistance of 4.26 mΩ·cm2. Meanwhile, a high breakdown voltage of 1044 V at I DS = 1 mA mm−1 compared to the conventional GaN HEMTs of 633 V was obtained. This approach is highly effective in simultaneously optimizing the breakdown voltage and the specific on-resistance of GaN HEMTs, while maintaining a large output current.

Extended legality of curved boundary integral method

The angular spectrum method is an efficient approach for synthesizing electromagnetic beams from planar electric field distributions. The electric field definition is restricted to a plane, which can introduce inaccuracy when applying the synthesized beam to curved surface features. The angular spectrum method can also be interpreted as a pure source method defining the field symmetrically with respect to the creation plane. Recently, we generalized that symmetric field method to arbitrary source distributions, which are valid at any point on compact, regular surface Ω in R3. We call this approach the Curved Boundary Integral method. The electromagnetic fields synthesized with this method satisfy the Helmholtz equation and are adjusted via amplitude and phase at the desired surface. The fields are obtained as a relatively simple integral. However, restrictions on where in space the synthesized field is valid were included in the mathematical proof length to avoid obscuring the main points. These restrictions can be significant depending on the shape and degree of curvature of surface Ω. In this article, we remove these restrictions so that the integral representation of the electromagnetic beam becomes valid at all points r∈R3∖Ω, with a minor restriction. Its modification can work even on Ω. We demonstrate the importance of this extended legality with a source field parametrized into the torus surface. The electromagnetic radiation of this structure would not be valid at any point in space without this extension. Finally, we show that by changing the order of integration, the field singularity at each source point is eliminated.