Electric Field Flux Research Articles

Regulation of Zinc Deposition by In Situ Formed Liquid Metal Interface for Dendrite‐Free Zinc Metal Anodes

AbstractUncontrolled dendrite growth, hydrogen evolution and corrosion challenges associated with zinc (Zn) anodes significantly restrict the practical application of zinc batteries. Herein, a liquid metal gallium (Ga) interface is in situ formed on carbon paper (CP) by electrochemical co‐deposition to construct a dendrite‐free Zn‐Ga@CP composite electrode which can regulate the transport and chemistry of Zn deposition at the electrode/electrolyte interface. Notably, the concurrent reduction of Zn2+ and Ga3+ on carbon paper results in the formation of a self‐supporting Zn electrode with 3D interpenetrating structure of Zn and Ga. Compared to zinc foil electrodes, the highly conductive liquid Ga layer lowers the nucleation energy barrier of Zn promotes the homogeneity of the electric field and ion flux, and induces uniform deposition of Zn. In addition, the low chemical activity of liquid Ga prevents a high rate of hydrogen evolution reaction and associated parasitic reactions. As a result, the Zn‐Ga@CP symmetric cell delivers stable cycling of >350 h at a discharge depth of 23.3% and ultra‐low voltage hysteresis. Moreover, the coin‐type and pouch‐type full cells exhibit excellent durability and good mechanical stability. This work provides a novel interface regulation strategy for achieving high‐performance dendrite‐free anode in Zn metal batteries.

Enhancing Reversibility and Stability of Mg Metal Anodes: High-Exposure (002) Facets and Nanosheet Arrays for Superior Mg Plating/Stripping.

Magnesium metal batteries (MMBs), recognized as promising contenders for post-lithium battery technologies, face challenges such as uneven magnesium (Mg) plating and stripping behaviors, leading to uncontrollable dendrite growth and irreversible structural damage. Herein, we have developed a Mg foil featuring prominently exposed (002) facets and an architecture of nanosheet arrays (termed (002)-Mg), created through a one-step acid etching method. Specifically, the prominent exposure of Mg (002) facets, known for their inherently low surface and adsorption energies with Mg atoms, not only facilitates smooth nucleation and dense deposition but also significantly mitigates side reactions on the Mg anode. Moreover, the nanosheet arrays on the surface evenly distribute the electric field and Mg ion flux, enhancing Mg ion transfer kinetics. As a result, the fabricated (002)-Mg electrodes exhibit unprecedented long-cycle performance, lasting over 6000 h (>8 months) at a current density of 3 mA cm-2 for a capacity of 3 mAh cm-2. Furthermore, the corresponding pouch cells equipped with various electrolytes and cathodes demonstrate remarkable capacity and cycling stability, highlighting the superior electrochemical compatibility of the (002)-Mg electrode. This study provides new insights into the advancement of durable MMBs by modifying the crystal structure and morphology of Mg.

Enhancing Reversibility and Stability of Mg Metal Anodes: High‐Exposure (002) Facets and Nanosheet Arrays for Superior Mg Plating/Stripping

AbstractMagnesium metal batteries (MMBs), recognized as promising contenders for post‐lithium battery technologies, face challenges such as uneven magnesium (Mg) plating and stripping behaviors, leading to uncontrollable dendrite growth and irreversible structural damage. Herein, we have developed a Mg foil featuring prominently exposed (002) facets and an architecture of nanosheet arrays (termed (002)‐Mg), created through a one‐step acid etching method. Specifically, the prominent exposure of Mg (002) facets, known for their inherently low surface and adsorption energies with Mg atoms, not only facilitates smooth nucleation and dense deposition but also significantly mitigates side reactions on the Mg anode. Moreover, the nanosheet arrays on the surface evenly distribute the electric field and Mg ion flux, enhancing Mg ion transfer kinetics. As a result, the fabricated (002)‐Mg electrodes exhibit unprecedented long‐cycle performance, lasting over 6000 h (>8 months) at a current density of 3 mA cm−2 for a capacity of 3 mAh cm−2. Furthermore, the corresponding pouch cells equipped with various electrolytes and cathodes demonstrate remarkable capacity and cycling stability, highlighting the superior electrochemical compatibility of the (002)‐Mg electrode. This study provides new insights into the advancement of durable MMBs by modifying the crystal structure and morphology of Mg.

Computational analysis of electromagnetic field exposure in passengers near high- current contact wire environments.

The electromagnetic environment of a railway station is composed of electrical, magnetic, and electromagnetic fields, which are generated by various sources such as traction current, voltage, pantograph-catenary arc, locomotive braking, wheel-rail rolling arc, and communication systems. However, there is public growing concern among the public about the potential negative human health effects of this electromagnetic environment. To analyze the distribution of electromagnetic fields in human tissues, electromagnetic simulation software is used to create a model that includes six track contact wires and four waiting passengers on three platforms. This model is used to analyze the magnetic field environment created by high currents in the contact wires of a multi-track high-speed railway station. By varying the loads on different contact wires, the distribution of electric field and magnetic flux density within human tissues of waiting passengers on different platforms is studied using this model. When the track is unoccupied, the calculation results show that the maximum values of the electric field and magnetic flux density of the passenger's human body tissue at the blind way on the platform and 1m of the blind way are 17.6mVm-1 and 52.7 μT, respectively. These values increase by 9.28mVm-1 and 16.4 μT compared to when the track is occupied. When more contact wires are loaded with currents, the electric field mode and magnetic flux density mode of human tissues increase at the same position on the platform. Specifically, when the contact wires of six tracks are loaded with current at the same time, the maximum values of the electric field mode and magnetic flux density mode of the waiting passengers' human tissues at the blind way on different platforms are 29.6mVm-1 and 88.1 μT, respectively. These maximum values are lower than the public electromagnetic exposure limits that are designated by the International Commission on Non-Ionizing Radiation Protection guidelines. The research results demonstrate that the magnetic field environment generated by the current in the contact wires of a railway station with six tracks does not pose a health risk to human tissues of passengers waiting at the blind way and 1m of the blind way on the platform. These findings can provide valuable data reference for the formulation of relevant standards for the design of electrified rail transit, as well as the suppression of electromagnetic interference and protection of human bioelectromagnetism.

Ionic memristive effects on the nanometre scale in metal oxides: Understanding the process of valence change

Relevance. The relevance of the study is due to the great potential of memristive effects, which are manifested in the change of material resistance under the influence of an external electric field and ionic fluxes. Aim. The aim is to analyse and study the mechanisms of ionic memristive effects, with a detailed consideration of the process of changing the valence of metal cations. Methodology. The work was based on the study of nanometre-sized metal oxides TiO2 and ZrO2. The materials were obtained by synthesis by chemical deposition using high-purity precursors. Results. The obtained results open up wide opportunities for the practical use of ionic membrane effects. The study of ionic memristive effects in TiO2 and ZrO2-based films has shown that the change in resistance occurs due to various mechanisms, including ionic migration, electrochemical reactions, and defect reorganization. Under the influence of an external electric field, a change in the resistance of both materials is observed. In TiO2, the resistance decreases with increasing voltage, while in ZrO2, an increase in resistance is observed. During additional experiments in the temperature range of 25-200 ℃, it was found that temperature significantly affects the ionic membrane effects. With its increase, a noticeable increase in the intensity of these effects in both materials is observed. Conclusions. The use of X-ray diffractometry and infrared spectroscopy revealed that changes in the valence of metal cations in both films occur under the influence of an electric field. The analysis of changes in the X-ray and infrared spectra showed the presence of modifications in the crystal and molecular structure in response to the electric field. In particular, the change in the positions and intensity of the peaks indicates a restructuring of the bonds in the crystal lattice. The paper proposes new studies to expand the understanding of these effects and to consider possible ways to improve membrane devices. The study of ionic memristive effects in TiO2 and ZrO2 is of great practical importance for the development of electronics and the creation of new generations of memristors and neuromorphic systems.

Reversible Zn electrodeposition enabled by interfacial chemistry manipulation for high-energy anode-free Zn batteries

Aqueous Zn batteries have attracted intensive interest in terms of the high safety and sustainable raw materials with low cost. However, the excess use of Zn anode greatly limits the practical energy density of batteries and arouses a threat to their real-life application. Here, a robust heterointerface composed of 0D metal nanodots and 2D metal carbide nanosheets with triple synergistic effects is designed to manipulate interfacial chemistry for anode-free Zn batteries. An interface of in situ anchoring ultrafine Sn nanodots on Na+ decorated MXene nanosheets is used as a model. The 2D Na-MXene promotes the Zn plating/stripping kinetics and homogenizes the distributions of electric field and ion flux. The high-affinity Zn binding sites of 0D Sn nanodots reduce the plating energy barrier and consequently manipulate the uniform Zn nucleation/growth. The in situ formed ZnF2 layer during Zn plating allows Zn ions to diffuse and shields side reactions. Consequently, the stable Zn plating/stripping with a high accumulated areal capacity of 5,000 mAh cm−2 is realized at high current density and plating capacity (10 mA cm−2∼20 mAh cm−2). Benefitting from triply synergistic effects derived from built cooperative interfaces, an anode-free Zn cell is constructed, proving ameliorative cyclic stability.

Extended Theory and Analysis of Potential Applications of Gauss's Law

This article analyzes and discusses the extended theory of Gauss's law and its potential applications in different fields. In the theoretical foundation section, the article elaborates on the definition, theory, and formulas of the traditional Gauss's law, providing mathematical derivations. Additionally, it reviews the applications of Gauss's law in electrostatics and gravitational fields, including aspects such as electric field flux, electric potential displacement, gravitational field, and mass distribution. In the potential application analysis section, the article explores the potential applications of Gauss's law in fields such as communications, acoustics, and medicine The expanded theories and potential applications of Gauss's theorem provide us with a unified mathematical framework at the macroscopic level for describing and explaining physical phenomena in different fields. By applying Gauss's theorem and its extended forms, we can better understand and explore various phenomena in the natural world, applying them to acoustics, medicine, and scientific research, thus advancing technological development and addressing practical problems.

New mixed finite element methods for the coupled Stokes and Poisson–Nernst–Planck equations in Banach spaces

In this paper we employ a Banach spaces-based framework to introduce and analyze new mixed finite element methods for the numerical solution of the coupled Stokes and Poisson–Nernst–Planck equations, which is a nonlinear model describing the dynamics of electrically charged incompressible fluids. The pressure of the fluid is eliminated from the system (though computed afterwardsviaa postprocessing formula) thanks to the incompressibility condition and the incorporation of the fluid pseudostress as an auxiliary unknown. In turn, besides the electrostatic potential and the concentration of ionized particles, we use the electric field (rescaled gradient of the potential) and total ionic fluxes as new unknowns. The resulting fully mixed variational formulation in Banach spaces can be written as a coupled system consisting of two saddle-point problems, each one with nonlinear source terms depending on the remaining unknowns, and a perturbed saddle-point problem with linear source terms, which is in turn additionally perturbed by a bilinear form. The well-posedness of the continuous formulation is a consequence of a fixed-point strategy in combination with the Banach theorem, the Babuška–Brezzi theory, the solvability of abstract perturbed saddle-point problems, and the Banach–Nečas–Babuška theorem. For this we also employ smallness assumptions on the data. An analogous approach, but using now both the Brouwer and Banach theorems, and invoking suitable stability conditions on arbitrary finite element subspaces, is employed to conclude the existence and uniqueness of solution for the associated Galerkin scheme.A priorierror estimates are derived, and examples of discrete spaces that fit the theory, include,e.g., Raviart–Thomas elements of orderkalong with piecewise polynomials of degree ≤k. In addition, the latter yield approximate local conservation of momentum for all three equations involved. Finally, rates of convergence are specified and several numerical experiments confirm the theoretical error bounds. These tests also illustrate the aforementioned balance-preserving properties and the applicability of the proposed family of methods.

Electromagnetic Frequency Pollution in Malawi: A Case of Electric Field and Magnetic Flux Density Pollution in Southern Africa

In this study, electric field and magnetic flux density pollution levels were measured in southern Africa, a case of Blantyre City in Malawi, between 2020 and 2021. Sixty short-term measurements were performed using Trifield Electro Magnetic Frequency meter model TF2 in 30 different locations. Five high-population-dense sampling points were selected from school campuses, hospitals, industrial areas, markets, residential areas, and within the commercial and business center (CBC) of Blantyre. Electric field and magnetic flux density pollution monitoring was conducted between 10:00-12:00 h and 17:00-19:00 h for short-range analysis. Short-range results show that the maximum measured electric field pollution were 249.24 mV/m and 207.85 mV/m between 10:00-12:00 and 17:00-19:00 respectively, which are below the public limits of 4200.00 mV/m for public exposure. Similarly, maximum short-range results for magnetic flux density were 0.073 G and 0.057 G between 10:00-12:00 and 17:00-19:00 respectively which are below the public limits of 2 G for public exposure. Both measured electric and magnetic flux density were compared with the International Commission on Non-Ionizing Radiation Protection (ICNIRP), World health organization (WHO), and Institute of electrical and electronics engineers (IEEE). It was determined that all measured values for both electric and magnetic flux density were smaller than set limits for non-ionizing radiation for both public and occupation health. More importantly, these background measurements establish a baseline for future changes to be compared against public safety.

Determination of Electric and Magnetic Field Calculation Uncertainty in the Vicinity of Overhead Transmission Lines

This paper presents a new approach for uncertainty determination of the electric field intensity and magnetic flux density calculation in the vicinity of overhead transmission lines. The proposed method is based on the law of propagation of uncertainty as defined in the Guide to the expression of Uncertainty in Measurement. A mathematical model is developed for determining the electric field intensity and magnetic flux density calculation uncertainty based on the Charge simulation method and method based on Biot – Savart law, respectively. The verification of the proposed method was performed by estimating the uncertainty of the electric field and magnetic flux density calculations for four single circuit and two double circuit high-voltage overhead transmission lines. The analysis of the obtained results demonstrates that the proposed method can be successfully used to determine the uncertainty of electric field intensity and magnetic flux density calculations in the vicinity of overhead transmission lines.

Radar Diagnosis of the Thundercloud Electron Accelerator

AbstractThunderstorm Ground Enhancements (TGEs) refer to correlated enhancements in surface electric field and gamma ray flux that are manifestations of electron runaway in the storm overhead. The electric field enhancements can be of positive or negative polarity. In this study, altitude‐resolved S‐band radar observations of graupel are used to demonstrate distinct differences in storm structure linked with these “positive” and “negative” TGEs. The physical interpretation rests on the well‐established temperature‐dependent tripole structure of thunderstorms, with the main negative charge of the tripole acting as an electron repeller. This interpretation is supported by case studies showing altitude‐stable convection, with shallow (deep) development linked with “positive” (“negative”) TGEs, and by case studies of collapsing storms that show upper dipole dominance early and lower inverted dipole dominance later when graupel particles descend from a colder to warmer temperature domain. In the case of many TGEs on Mt Aragats (3.2 km MSL), the temperature‐dependent altitude of downward electron acceleration and avalanching may be sufficiently distant (>500 m) from surface detectors that the energetic electrons (1–10 MeV) are not likely avalanche/runaway electrons. Instead, they are Compton‐scattered and pair‐produced electrons from bremsstrahlung gamma radiation emanating from the high‐field avalanche region aloft. These inferences are consistent with GEANT4 calculations that identify the physical origins of energetic electrons at the surface.

Development of two dimensional full wave spectral code for the ICRF heating and current drive research including scrape-off layer in tokamaks

It is important for an ICRF full wave code to simulate the SOL (Scrape Off Layer) plasma as well as the core inside of the LCFS (Last Closed Flux Surface) for the precise prediction of the coupling between the antenna and the core plasma in tokamaks. To this end, a two dimensional full wave code based on a Fourier spectral algorithm has been developed. The spectral algorithm and procedures are described and the simulation results for the minority heating in KSTAR are reported including electric field, power absorption and power flux.

Role of the edge stochastic layer in density pump-out by resonant magnetic perturbations

The role of the edge stochastic layer on particle transport is addressed in DIII-D plasmas with applied resonant magnetic perturbations (RMPs) causing density pump-out (a term used to denote the density reduction at the top of the pedestal due to the applied RMPs). Using an analytical model that adds the stochastic parallel transport of electrons (Harvey et al 1981 Phys. Rev. Lett. 47 102) to the fluid equations, the ambipolar radial electric field and particle flux are calculated simultaneously. In this model the nonambipolar electron particle flux, driven by the stochastic magnetic field, is predominantly balanced by the nonambipolar perpendicular ion flux, driven by toroidal viscosity, across a narrow stochastic layer of order two percent of the plasma radius (0.98 < ψ n < 1). The model reproduces the level of density pump-out and its dependence on RMP amplitude near the separatrix for three plasma discharges for which the pedestal foot is at medium to high collisionality . The experimentally observed and numerically tested inverse density dependence of density pump-out (Hu et al 2020 Nucl. Fusion 60 076001) is accurately captured by the model: an increase in collisionality with density in the pedestal foot results in a decrease in stochastic diffusivity, and hence a decrease in the level of pump-out.

Charge‐Enriched Strategy Based on MXene‐Based Polypyrrole Layers Toward Dendrite‐Free Zinc Metal Anodes

AbstractAlthough zinc metal anodes have some intrinsic advantages for aqueous zinc ion batteries, the notorious dendrites hamper its practical applications. Herein, a charge‐enriched strategy through MXene‐based polypyrrole (MXene‐mPPy) layers is explored toward dendrite‐free Zn metal anode. The MXene‐mPPy layers composed of mesoporous PPy on both sides of Ti3C2Tx‐MXene exhibit an exceptional charge enrichment ability (149 F g−1, 5 mV s−1), which is beneficial not onlying terms of accumulating the charge levels, but also to homogenize the dispersions of electric field and ion flux as used as an artificial interface on a Zn anode. Thus, a dendrite‐free Zn anode with an ultralong cycling lifespan up to 2500 h and superior rate capability is achieved, which is further applied as an anode for aqueous zinc ion batteries with a long‐term span over 3000 cycles at 10 A g−1.

Proca balls with angular momentum or flux of electric field

Within SU(2) Higgs-Proca theory, we obtain a family of nontopological static solutions describing localized, finite-energy configurations (Proca balls). The gauge symmetry of the theory is explicitly broken by introducing a vector Proca field whose components have different masses. Such solutions describe particlelike systems, the crucial feature of which is that they either possess a nonzero total angular momentum or have a flux of electric field through the plane of symmetry of such objects. It is shown that the angular momentum is provided by static crossed electric and magnetic fields. The existence of the solutions is caused by the fact that we circumvent the conditions of the no-go theorem, according to which there are no stationary and axially symmetric spinning excitations for the 't Hooft-Polyakov monopoles, Julia-Zee dyons, sphalerons, and also vortices. The dependence of some integral physical quantities on the ratio of the Proca-field masses is studied. It is demonstrated that the inclusion of external sources (charges) enables one to obtain solutions with equal Proca-field masses. We also discuss the possibilities of using quarks as sources of the Proca field under investigation and for treating the Proca balls as glueballs in SU(2) Higgs-Proca theory.

Results of risk assessment for occupational electromagnetic exposures

In 2016, a Hungarian law was introduced in accordance with the valid guidelines of the European Parliament related to the occupational exposures of electromagnetic fields. By this law, it is mandatory to evaluate and assess all the risks of operating equipment with voltage levels above 100 kV or currents above 100 A in the industry. Based on this guideline, experts of Group of High Voltage Technology and Equipment of Budapest University of Technology and Economics have performed several risk assessments based on the prescribed requirements.In several cases, exposures of electric, magnetic and electromagnetics fields have exceeded their limits: not only in case of worst-case simulations, but during on-site measurements, measured range of electric field and magnetic flux density was in the range which requires additional protection. To reduce risks to acceptable levels, practically applicable ways of protection must be prescribed to guarantee the requested level of safety, like improved medical examinations, restriction of approach or additional personal protective gears. Based on the results, industrial processes were modified, best practices have been declared, and critical activities were reported for the government – as requested by the guideline. The main aim of the introduction of these results is to highlight the importance of this topic, to assess the so-called “invisible” sources of dangers which are unfortunately often neglected. It is also crucial to introduce the basics and typical ranges of electromagnetic exposures for the employees of the affected facilities. Education, as a second step, is also an important part of this job. This paper summarizes the typical scenarios and magnitudes of exposures in case of occupational applications. Key data of analysis and basis of risk assessment was the measured electric field and magnetic flux density values compared to the current limits prescribed in the territory of the EU.

Long-time behavior of a nonlinear electromagnetic wave in vacuum beyond the linear approximation

A quantum nature of vacuum is expected to affect electromagnetic fields in vacuum as a nonlinear correction, yielding nonlinear Maxwell's equations. We extend the finite-difference time-domain (FDTD) method in the case that the nonlinear electromagnetic Lagrangian is quartic with respect to the electric field and magnetic flux density. With this extension, the nonlinear Maxwell's equations can be numerically solved without making any assumptions on the electromagnetic field. We demonstrate examples of self-modulations of nonlinear electromagnetic waves in a one-dimensional cavity, in particular, in a timescale beyond an applicable range of linear approximation. A momentarily small nonlinear correction can accumulate and a comparably large self-modulation can be achieved in a long timescale even though the electromagnetic field is not extremely strong. Further, we analytically approximate the nonlinear electromagnetic waves in the cavity and clarify the characteristics, for example, how an external magnetic flux density changes the self-modulations of phase and polarization.

A New Stripline-Based Atmospheric Pressure Microwave Plasma Sheet Source Designed for Surface Modification of Materials.

A new type of microwave plasma source is presented in which plasma at atmospheric pressure is generated inside a quartz rectangular flat box placed in a stripline supplied by a 2.45 GHz coaxial line. The plasma has a sheet shape and is designed for surface modification. Electric field and power flux distributions, tuning characteristics, and power characteristics (ratios of radiated, absorbed, and entering power) are numerically studied for three configurations: open, semi-closed, and closed. The calculations show that near-zero radiation reduction is possible only for the closed configuration, while the ratio of radiated power to entering power is always greater than 30% for the other configurations. The moving plunger is not sufficient for the ratio of reflected to incident power to fall below 20% for both the closed and open configurations. This is possible for the semi-closed configuration, but then the radiated power is the highest. The experiment shows that for the same entering power, the plasma volume is largest for the closed configuration and smallest for the open configuration, which we attribute to the difference in radiated power. The plasma generated using the closed stripline configuration has a larger volume than plasma generated using the rectangular waveguide.

Linear Energy Density and the Flux of an Electric Field in Proca Tubes

In this work, we study cylindrically symmetric solutions within SU(3) non-Abelian Proca theory coupled to a Higgs scalar field. The solutions describe tubes containing either the flux of a color electric field or the energy flux and momentum. It is shown that the existence of such tubes depends crucially on the presence of the Higgs field (there are no such solutions without this field). We examine the dependence of the integral characteristics (linear energy and momentum densities) on the values of the electromagnetic potentials at the center of the tube, as well as on the values of the coupling constant of the Higgs scalar field. The solutions obtained are topologically trivial and demonstrate the dual Meissner effect: the electric field is pushed out by the Higgs scalar field.

Effect of electric current on the microstructural refinement of pure aluminum

The effect of electric current on the refinement of pure aluminum during solidification was investigated based on microstructural observations and numerical simulations. Coarse columnar grains are observed without the application of direct current (DC off), while equiaxed grains clearly exist under the application of electric current during solidification; the area fraction of the equiaxed zone increased up to 66% under electric current, whereas it is negligible in DC off condition. Also, grain size decreased drastically to 221 μm under electric current compared to that of several mm in DC off condition. The grain refinement was affected by the electrical conditions such as the intensity and duration of applied electric current. The flow in liquid aluminum was observed experimentally from the homogenization of the cooling curves measured at different heights and the oscillations in the cooling curves, when electric current was applied during solidification. Through numerical analysis, it was found that the circulating flow of liquid aluminum was developed by the Lorentz force induced by a combination of the electric current density field and magnetic flux density field under electric current. Moreover, the circulating flow could affect grain refinement by providing additional nuclei through dendrite fragmentation. However, under extreme conditions of relatively high electrical energy, the refining effect could disappear because of the retardation of solidification or remelting of nuclei, induced by the Joule heating effect. This study proves that electric current plays an important role in the control of solidification structure.