Dynamics Of Electromagnetic Field Research Articles

Electrically charged black holes in [formula omitted]-Euler–Heisenberg theory

Drawing on the concept of the non-linear dynamics of electromagnetic fields in vacuum in terms of the Euler–Heisenberg system, a static and spherically symmetric black hole solution is derived by coupling the Euler–Heisenberg term and F(R) gravity. In applying the curvature singularity tools, the black hole solution induces a singular behaviour at the centre r=0 while exhibiting a regular shape at high distances. Using the heat capacity (CQ) and the Helmholtz free energy (F), we analyse the thermodynamic stability locally and globally. Furthermore, an investigation is conducted using class tools of Geometrothermodynamics (GTs) features such as Weinhold, Ruppeiner, Hendi–Panahiyan–Eslam–Momennia (HPEM), and Quevedo to identify phase transition points associated with heat capacity, including both physical boundary points (root of the heat capacity) and second critical phase transition points (divergent points of the heat capacity). We have even examined the relevant sparsity of Hawking radiation, showing how the black hole solution behaves as a black body at specific limits. Overall, this study enhances our knowledge of the mergers of a class of non-linear dynamics of electromagnetic fields in a vacuum within F(R) gravity by modelling black hole solutions.

Chiral symmetry restoration and the ultraquantum limit of axionic Charge Density Waves in Weyl Semimetals

A new mechanism for chiral symmetry restoration at extreme high magnetic fields is proposed in the context of the Magnetic Catalysis scenario in Weyl Semimetals. Contrary to previous proposals, here we show that, at very large magnetic fields, the transverse velocity of the axion field, the phase mode of the chiral condensate \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\langle \\overline{\\Psi }\\Psi \\rangle $$\\end{document}, becomes effectively one-dimensional and its fluctuations destroy a possible nonzero value of this fermionic condensate. We also show that, despite of the U(1) chiral symmetry not being broken at extremely large magnetic fields, the spectrum of the system is comprised by a well defined gapless bosonic excitation, connected to the axion mode, and a correlated insulating fermionic liquid that is neutral to U(1) chiral transformations. When the theory is supplemented with the inclusion of dynamical electromagnetic fields, the chiral symmetry is broken again, and the conventional scenario of magnetic catalysis can be recovered.

Charged participants and their electromagnetic fields in an expanding fluid

We investigate the space-time dependence of electromagnetic fields produced by charged participants in an expanding fluid. To address this problem, we need to solve the Maxwell's equations coupled to the hydrodynamics conservation equation, specifically the relativistic magnetohydrodynamics (RMHD) equations, since the charged participants move with the flow. To gain analytical insight, we approximate the problem by solving the equations in a fixed background Bjorken flow, onto which we solve Maxwell's equations. The dynamical electromagnetic fields interact with the fluid's kinematic quantities such as the shear tensor and the expansion scalar, leading to additional non-trivial coupling. We use mode decomposition of Green's function to solve the resulting non-linear coupled wave equations. We then use this function to calculate the electromagnetic field for two test cases: a point source and a transverse charge distribution. The results show that the resulting magnetic field vanishes at very early times, grows, and eventually falls at later times.

Third-harmonic scattering optical activity: QED theory, symmetry considerations, and quantum chemistry applications in the framework of response theory.

In this work, expressions for the third-harmonic scattering optical activity (THS-OA) spectroscopic responses are derived by combining molecular quantum electrodynamics (QED) and response theory, allowing their computational implementation. The QED theory of THS-OA presented here is meant to be an extension of a previous study by Andrews [Symmetry 12, 1466 (2020)]. In particular, the THS-OA phenomena are described within the Power-Zienau-Woolley multipolar Hamiltonian by including the electric-dipole, magnetic-dipole, and electric-quadrupole interactions for the absorption as well as the emission processes between the dynamic electromagnetic field (the photons) and matter. Moreover, we derive the expressions for the differential scattering ratios as a function of the scattering angle defined by the wavevectors of the incident and scattered photons. We show how the pure and mixed second hyperpolarizabilities can be obtained in the framework of response theory as specific cases of a generic cubic response function, thus enabling the computational implementation of THS-OA spectroscopy. We prove the origin-independence of the theory for exact wavefunctions. Preliminary computations on a prototype chiral molecule (methyloxirane) are considered together with an analysis of the basis set convergence and of the origin-dependence.

Jupiter's Coordinate System Transformations: A Guide for Future Studies of the Jovian System

AbstractThe Juno mission, launched in 2011, has significantly advanced our understanding of Jupiter's gravitational field, the solar wind and interplanetary conditions along its orbit, the evolution of Jupiter's high‐latitude magnetosphere and aurorae, the dynamics of plasma and electromagnetic fields in its magnetosphere, etc. As a result, new requirements for the definition and improvement of existing coordinate systems have arisen due to engineering implementation and the understanding of various scientific questions that rely on different preferred coordinate systems. In this paper, we first review the primary Jupiter's coordinate systems, including newly defined systems, such as the Jupiter Solar MAGnetosphere (JSMAG) and Jupiter Equatorial Inertial (JEIJ2000) coordinate systems, as well as a precisely defined orthogonal Jupiter Heliospheric (JH) coordinate system. We have also improved several magnetic field‐related coordinate systems and these systems support different Jupiter magnetic field models. The angular deviation of solar position‐related coordinate systems oriented by the semi‐analytical ephemerides TOP2013 is less than 70 milliarcseconds during the time span from 1800 to 2200 year. In addition, we propose a relatively simple, fast, and accurate transformation method, addressing the complexity of traditional coordinate system transformations entirely based on rotation axes and angles. This method introduces a basic coordinate system in which the unit vectors of all coordinate axes are represented. Finally, the comparison of our calculation with the published data indicates the high efficiency and accuracy of this work, which can be used as a basic tool for future Jovian system explorations from 1800 to 2200 year.

A dynamic electromagnetic field assisted boronic acid-modified magnetic adsorbent on-line extraction of cis-diol-containing flavonoids from onion sample

A dynamic electromagnetic field assisted boronic acid-modified magnetic adsorbent on-line extraction of cis-diol-containing flavonoids from onion sample

Numerical study for development of subsurface crack detection using pulsed eddy current and swept frequency eddy current

Root-deck crack, a type of subsurface damage, is one of the most concerning fracture issues on orthotropic steel decks. Therefore, the development of novel and easy-to-use subsurface damage detection technique is crucial to detect damage at an early stage to prevent the occurrence of major damage. In this paper, new methods to process the response signal of the eddy current technique (ECT) using the normalised peak and time to zero crossing of the change in induced voltage, and the peak and frequency at the peak of the normalised change in phase angle, are proposed. Based on these newly proposed methods, a probe configuration optimisation study was carried out using dynamic electromagnetic field analysis. From numerical studies, the cup-core probe promises high capability to detect damage located 10 mm below the surface of a 12 mm steel plate and maintain the sensitivity at an eccentric position. Furthermore, the newly proposed signal processing methods enable users to interpret response signals for subsurface damage detection in a more comprehensive way than conventional methods.

Inversion of one‐dimensional parameters of horizontal multi‐layer soil model based on dynamic state electromagnetic field theory and ant colony optimization algorithm

AbstractBuilding a reliable soil model is a prerequisite for accurately calculating the ground potential distribution of the grounding grid. Research shows that the soil electrical parameters are frequency‐dependent, so frequency domain inversion of soil parameters should consider the soil inhomogeneity and the frequency characteristic of parameters. A method for retrieving parameters of horizontal multilayer soil model is proposed. The theoretical formula of apparent complex resistivity with considering dynamic state electromagnetic field theory is derived from Green's function. Discrete dynamic state complex image method is introduced to solve the infinite integral in Green's function. Ant colony optimization algorithm is applied to optimize the inversion process of soil parameters. In the first stage, applicability of this method is confirmed by interpreting field data under DC field. DC parameters including DC resistivity, thickness and number of layer are determined. The performance of different optimization algorithms in terms of computational efficiency is compared at this stage. In the second stage, soil resistivity and relative dielectric constant are retrieved by inverting frequency domain experimental data. Different representations based on quasi‐static electromagnetic field and dynamic state electromagnetic field theories are taken into account. The frequency characteristic of soil parameters is concluded by discussing the inversion results. In the study of parameter inversion of horizontal multi‐layer soil model, our method has shown strong performance in computational efficiency and accuracy of inversion results.

Charge diffusion in relativistic resistive second-order dissipative magnetohydrodynamics

We study charge diffusion in relativistic resistive second-order dissipative magnetohydrodynamics. In this theory, charge diffusion is not simply given by the standard Navier-Stokes form of Ohm's law, but by an evolution equation which ensures causality and stability. This, in turn, leads to transient effects in the charge diffusion current, the nature of which depends on the particular values of the electrical conductivity and the charge-diffusion relaxation time. The ensuing equations of motion are of so-called stiff character, which requires special care when solving them numerically. To this end, we specifically develop an implicit-explicit Runge-Kutta method for solving relativistic resistive second-order dissipative magnetohydrodynamics and subject it to various tests. We then study the system's evolution in a simplified 1+1-dimensional scenario for a heavy-ion collision, where matter and electromagnetic fields are assumed to be transversely homogeneous, and investigate the cases of an initially non-expanding fluid and a fluid initially expanding according to a Bjorken scaling flow. In the latter case, the scale invariance is broken by the ensuing self-consistent dynamics of matter and electromagnetic fields. However, the breaking becomes quantitatively important only if the electromagnetic fields are sufficiently strong. The breaking of scale invariance is larger for smaller values of the conductivity. Aspects of entropy production from charge diffusion currents and stability are also discussed.

Spin dynamics in nonuniform electromagnetic wave fields

Based on solution of Dirac equation, the dynamics of a quantum particle with a half-integer spin (fermion) in the field of an arbitrary inhomogeneous electromagnetic wave has been analysed revealing some features of bound motion defined by so-called optical lattice (channeling). It is shown that, in the first order of expansion in longitudinal energy, the effective interaction potential of a fermion coincides with that of a scalar particle, while the spin features of interaction in this field appear only in the next expansion term. Semiclassical approximation in a spin dynamics for an arbitrary particle in an inhomogeneous optical lattice field indicates that at channeling conditions the polarisation vector affirms a smooth precession, the rate of which is defined by the difference between the magnetic moment of the particle and its anomalous part.

Dimensional reduction of the Dirac theory

We perform a reduction from three to two spatial dimensions of the physics of a spin- fermion coupled to the electromagnetic (EM) field, by applying Hadamard’s method of descent. We consider first the free case, in which motion is determined by the Dirac equation, and then the coupling with a dynamical EM field, governed by the Dirac–Maxwell equations. We find that invariance along one spatial direction splits the free Dirac equation in two decoupled theories. On the other hand, a dimensional reduction in the presence of an EM field provides a more complicated theory in dimensions, in which the method of decent is extended by using the covariant derivative. Equations simplify, but decoupling between different physical sectors occurs only if specific classes of solutions are considered.

Determining the dynamics of electromagnetic fields, air ionization, low-frequency sound and their normalization in premises for computer equipment

This paper reports a study into the quantitative values and dynamics of physical factors in premises and workplaces of stationary and portable computers. The factors that are practically not perceived by the senses of operators were investigated. It is established that modern monitors do not generate electromagnetic fields of hygienically significant levels. System units generate electric fields (18‒22 V/m) and magnetic fields (220‒245 nT) that are approaching the maximum permissible. Sources of uninterruptible power supply and fluorescent lighting systems generate excess magnetic fields (up to 2250 nT and 2300 nT), respectively. The main excessive factor for portable computers is electric fields (up to 9 kV/m), which is the cause of air deionization in the user's zone of stay. It is shown that one system unit in the normative volume of the room (20 m3) deionizes air (into 100 cm-3 positive and 200 cm-3 negative). The generation of ions by modernized laser printers and photocopiers of various models (up to 1500 cm-3 and 2800 cm-3, respectively) was investigated. The distances at which the ionic composition of the air corresponds to the background values (1.0‒1.5 m) were determined. That requires the introduction of artificial air ionization in workplaces of users and a decrease in the levels of electrostatic fields. The spectral composition and amplitudes of magnetic fields of external power supplies of laptop computers were determined. It is shown that the difference in sound levels measured on the scales "Lin" and "A" reaches 24 dB, which indicates a significant impact of infrasound on users. Membrane-type protective panels configured for maximum resonant frequencies of low-frequency sound and infrasound have been proposed

Ultra-fast polarization of a thin electron layer in the rotational standing-wave field driven by double ultra-intense laser pulses

We explore radiative polarization of electrons in a standing-wave formed by two circularly-polarized laser pulses irradiating a thin layer. Here the electron radiative spin dynamics in external electromagnetic fields is described by the generalized Sokolov–Ternov model implemented in the particle-in-cell simulations. We find that significant polarization is established in roughly one laser period from the circular motion in the standing wave. However, such motion is unstable at the magnetic nodes such that electrons migrate to different phases. The beam polarization is then transferred to transverse directions following the T-BMT precession and splits into two groups with opposite signs. The induced polarization distribution allows for filtering out electron population of high polarization purity via certain emitting angles and energies, approaching maximum of 78% polarization at light intensities of the order ∼1023 W cm−2.

Thermodynamic equilibrium condition and the first law of thermodynamics for charged perfect fluids in electromagnetic and gravitational fields

We provide a proof of the necessary and sufficient condition on the profile of the temperature, chemical potential, and angular velocity for a charged perfect fluid in dynamic equilibrium to be in thermodynamic equilibrium not only in fixed but also in dynamical electromagnetic and gravitational fields. In passing, we also present the corresponding expression for the first law of thermodynamics for such a charged star.

Novel Method of Electromagnetic Field Measurements of the Human Brain.

IntroductionAdvancements in neuroimaging have changed the field of medicine. Computed tomography (CT) and magnetic resonance imaging (MRI) typically produce a static image of the brain, while continuous electroencephalogram (EEG) data is limited to the cortical surface. The brain’s chemical reactions produce an electric circuit that generates a magnetic field. We seek to test the ability of a non-contact sensor to measure the human brain’s electromagnetic field (EMF).MethodsA lightweight, inexpensive construct was designed to hold EMF sensors to non-invasively measure the human brain’s dynamic EMF. Measurements were conducted on non-clinical human volunteers. Background data without the human subjects was obtained, followed by introducing human subjects. Motionless human subject data was obtained, followed by a subject performing a task. Finally, a subject received auditory stimulation, and data was obtained.ResultsOur non-contact sensor was able to detect a difference between background activity without a human subject and the electromagnetic field of a human brain within the scalp and skull. Detectable differences in magnetic field potential were also obtained when the subject performed a task and received auditory stimulation.ConclusionIt is possible to continuously measure living human brain dynamic electromagnetic fields throughout the entire brain in a non-contact, non-invasive, continuous manner through the human scalp and skull in the standard environment. The signals are unique to the individual human and can be differentiated from background activity.

Nonlinear dynamics of electromagnetic field and valley polarization in WSe2 monolayer

The linear and nonlinear optical response of a WSe2 monolayer is investigated by a two-dimensional Maxwell plus time-dependent density functional theory with spin–orbit interactions. By applying chiral resonant pulses, the electron dynamics along with high harmonic generation are examined at weak and strong laser fields. The WSe2 monolayer shows linear optical response at the intensity I = 1010 W/cm2, while a complex nonlinear behavior is observed at I = 1012 W/cm2. The nonlinear response of the WSe2 monolayer in terms of saturable absorption is observed at a strong laser field. By changing the chirality of the resonant light, a strong circular dichroic effect is observed in the excited state population. A relatively weak laser field shows effective valley polarization while a strong field induces a spin-polarized carrier peak between K(K′) and Γ-point via a nonlinear process. On the other hand, the strong laser field shows high harmonics up to the 11th order. Our results demonstrate that a circularly polarized resonant pulse generates high harmonics in the WSe2 monolayer of order 3n ± 1.

Lorentz Violation by the Preferred Frame Effects and Cosmic and Gamma Ray Propagation

The ‘relativity with a preferred frame’, designed to reconcile the relativity principle with the existence of the cosmological preferred frame, incorporates the preferred frame at the level of special relativity (SR) while retaining the fundamental spacetime symmetry, which, in the standard SR, manifests itself as Lorentz invariance. In this paper, the processes, accompanying the propagation of cosmic rays and gamma rays through the background radiation from distant sources to Earth, are considered on the basis of particle dynamics and electromagnetic field dynamics developed within the framework of the ‘relativity with a preferred frame’. Applying the theory to the photopion-production and pair-production processes shows that the modified particle dynamics and electrodynamics lead to measurable signatures in the observed cosmic and gamma-ray spectra which can provide an interpretation of some puzzling features found in the observational data. Other processes responsible for gamma-ray attenuation are considered. It is found, in particular, that electromagnetic cascades, developing on cosmic microwave background and extragalactic background light, may be reduced or suppressed due to the preferred frame effects which should influence the shape of the very high-energy gamma-ray spectra. Other possible observational consequences of the theory, such as the birefringence of light propagating in vacuo and dispersion, are discussed.

Trapping PM2.5 particles from electrostatic precipitator equipped with magnetic field under different gas velocities

The aim of this work is to investigate the effects of magnetic field and ionic wind on the ability of a wire-plate electrostatic precipitator (ESP) to trap fine particles. A theoretical model of multi-field coupling between gas flow field, particle dynamic field and electromagnetic field was established, and a grid model was built by GAMBIT software. The collection efficiency under different gas velocities was calculated in FLUENT software where the electric field force and the magnetic field force were introduced by User Defined Function (UDF). The numerical results indicate that both ionic wind and applied magnetic field can effectively improve the PM2.5 collection efficiency in a wire-plate ESP, and the smaller the particle size, the more obvious the improving effects are. With the increase of gas velocity, PM2.5 collection efficiency has a nonlinear declining trend, but the contribution of ionic wind or magnetic field to the collection efficiency increases. The trapping performance of the wire-plate ESP under the combined action of the two factors is better than that of considering one of them separately. The research results can open up a new design idea and direction for the performance upgrading of the wire-plate ESP.

Electric-field-promoted photo-electrochemical production of hydrogen from water splitting

Given that conversion efficiencies of incident solar radiation to liquid fuels, e.g., H2, are of the order of a few percent or less, as quantified by ‘solar to hydrogen’ (STH), economically inexpensive and operationally straightforward ways to boost photo-electrochemcial (PEC) H2 production from solar-driven water splitting are important. In this work, externally-applied static electric fields have led to enhanced H2 production in an energy-efficient manner, with up to ~30–40% increase in H2 (bearing in mind field-input energy) in a prototype, open-type solar cell featuring rutile/titania and hematite/iron-oxide (Fe2O3), respectively, in contact with an alkaline aqueous medium (corresponding to respective relative increases of STH by ~12 and 16%). We have also performed non-equilibrium ab-initio molecular dynamics in both static electric and electromagnetic (e/m) fields, for water in contact with a hematite/iron-oxide (001) surface, observing enhanced break-up of water molecules, by up to ~70% in the linear-response régime. We discuss the microscopic origin of such enhanced water-splitting, based on experimental and simulation-based insights. In particular, we external-field direction at the hematite surfaces, and scrutinise properties of the adsorbed water molecules and OH– and H3O+ species, e.g., hydrogen bonds between water-protons and the hematite surfaces’ bridging oxygen atoms, as well as interactions between oxygen atoms in adsorbed water molecules and underlying iron atoms.

Microwave heating in heterogeneous catalysis: Modelling and design of rectangular traveling-wave microwave reactor

Microwave irradiation can intensify catalytic chemistry by selective and controlled microwave-catalytic packed-bed interaction. However, turning it to reality from laboratory to practical applications is hindered by challenges in the reactor design and scale-up. Here, we present a novel, rectangular traveling-wave microwave reactor (RTMR) and provide an easy-to-handle, 3-step design procedure of such reactor. The multiphysics model couples the electromagnetic field, heat transfer, and fluid dynamics in order to optimize the geometrical parameters and operational conditions for the microwave-assisted heterogeneous catalysis. The results show that the microwave energy input/output ports should be well-positioned and matched; otherwise, it would significantly decrease energy efficiency. In terms of microwave transmission, the RTMR presents a mix between the standing wave and the traveling-wave systems. Gas space velocity and input temperature significantly affect the temperature profile, and gas–solid temperature can present no significant difference under certain gas–solid contact.