Transverse Electromagnetic Waves Research Articles

Statistical evaluation of electric field distributions in 3D composites with a random spatial distribution of dielectric inclusions

Electromagnetic applications of composites often impose constraints on the internal electric fields, such as an upper limit on the field strength to prevent local heating or dielectric breakthrough. However, owing to heterogeneity, the local fields in a composite differ from those in a homogeneous material. Moreover, they are accessible neither by experiment nor by effective medium theories, at least for arbitrary microstructures. In this work, we use numerical simulations to evaluate the electric field distribution and the effective permittivity for 3D systems of monodisperse impenetrable spheres dispersed in a continuous matrix phase. We restrict ourselves to loss-free dielectric materials and to a random spatial distribution of particles. Samples are placed in a parallel plate waveguide and exposed to a transverse electromagnetic wave. The local field amplitudes are calculated via the finite element method and are normalized to those of a homogeneous sample exhibiting the same effective permittivity and geometry. We analyze the distribution of the local electric field strength in both constituents, namely, particles and matrix. Thus, we evaluate mean values and standard deviations as well as the field strengths characterizing the highest and lowest percentiles. Increasing particle concentration or permittivity enhances heterogeneity, and so the local electric field strength in some domains can become much higher than its average value. The methods we apply here can also be used in further investigations of more complex systems, including lossy materials and agglomerating particles.

To a dispersion law of an electromagnetic wave in a medium having a double anisotropy

Dispersion relations for a transverse electromagnetic wave in a hypothetical medium having a low crystalline symmetry and double anisotropy are formulated phenomenological based on the general concepts of Maxwell's equations. Formalism for electrical and magnetic ordering of a medium is represented by tensor coefficients of the second rank in a general coordinate system corresponding to an external problem of incidence, reflection and refraction of a transverse wave at the interface. Based on the obtained dispersion law, the Snell law of refraction for the wave vector is displayed, as well as, some special cases for a section of a wave surface and a ray surface in the plane of incidence. Following Fresnel approach as usual, two characteristic types of linear polarization of an electric induction vector of a propagating wave are considered for a wave entering a double anisotropic medium at an arbitrary angle to the interface. Based on a character of a cross-section of a wave surface and of a ray surface for the plane of incidence, the degree of influence of anisotropy on a propagating field is discussed in terms of external/internal conic refraction of ordinary/extraordinary waves in a transparent medium. Following to initially general form of the permittivity ε^ and the magnetic permeability μ^ tensors some particular cases of a more favorable choice of coordinate system are analyzed to decrease a number of non-zero components in mentioned tensors, as well as to decrease in the number of elements in vector relations.

Polarization rotation and exact transverse electromagnetic wave solutions in topological insulators

Polarization rotation and exact transverse electromagnetic wave solutions in topological insulators

A New Approach to Nuclear Fusion Based on Muon Catalysis by Means of High-Energy Ball Lightning and an Accelerative Mechanism

A new method of realizing nuclear fusion reactions based on muon catalysis and the accelerative mechanism is proposed. High-energy ball lightning is periodically generated in a reactor chamber filled with deuterium gas and directed into a container containing liquid tritium. The entry of ball lightning into the tritium is accompanied by the generation of muons and mesomolecules due to a cascade process. Following the ball lightning, a high-energy plasma jet moves under the influence of traveling transverse electromagnetic waves. Deuterium ions and electrons of the jet, accelerated by intense transverse electromagnetic waves, interact with the tritium. Nuclear fusion reactions occur with the participation of muonic molecules at very low temperature. The developed method resolves all physical and technical problems that are inherent in existing traditional methods.

Dispersion Equations of Transverse Electromagnetic Waves Narrowly Localized Near the Interface between the Media with Different Graded-Index Profiles

"Combinations of three pairs of contacting media with linear, exponential, and parabolic profiles of dielectric permittivity are described theoretically. Three new types of narrowly localized transverse electric waves propagating along the interfaces between the considered graded-index media are found. The exact dispersion equations for each type of the waves determining the effective refractive index in dependence on optical and geometric characteristics are obtained. The influence of the thicknesses of the graded-index layers on dispersion equation solutions is analyzed. It is found that the effective refractive index increases with an increase in the thickness of the gradedindex layers in all considered combinations of the contacting media. The thickness of the parabolic graded-index profile has the least significant effect on the effective refractive index, compared to the linear and exponential ones. "

FEATURES OF NEW CYCLOTRON RESONANCES, AS WELL AS CONDITIONS FOR RESONANT ACCELERATION OF CHARGED PARTICLES IN A VACUUM WITHOUT A MAGNETIC FIELD

It is shown that the known conditions for cyclotron resonances are strictly valid only under autoresonance conditions or in the nonrelativistic case. In other cases, it is necessary to use the conditions established in the present work. The main features of charged particle dynamics under new resonant conditions are presented. Conditions are found for infinite acceleration of electrons by a transverse electromagnetic wave in a vacuum without a magnetic field.

Signatures of quantized magnetic field on the nonlinear Landau damping of transverse electromagnetic waves

A quantum kinetic approach alongwith the Landau theory of quantization (LQ) is utilized to study the impact of the magnetic field on the nonlinear Landau damping (NLD) of transverse electromagnetic (EM) waves in a degenerate electron-ion plasma. The gyratory motion of fermions around the magnetic field (H) lines gets quantized into the Landau levels and consequently the associated Fermi–Dirac distribution function becomes modified with the fermion cyclotron frequency under the limit l ℏ ω ce − ε Fe ≫ k B T e , where l is the orbital quantum number with all other standard notations. In this context, the density oscillations due to electrons are calculated in the presence of the LQ parameter η( = ℏ ω ce /ε Fe < 1) and ion density perturbations are computed using the framework of Maxwell distribution. A new type of kinetic nonlinear Shrödinger equation is derived in the presence of η, which involves nonlocal nonlinear term responsible for the NLD of EM waves. Furthermore, longitudinal wave modes are investigated to account for quantization parameter η. The LQ is also shown to absorb oscillation spectra of the linear ion-acoustic mode. The present findings might be helpful to understand the impact of the H field on the nonlinear interaction of EM waves with astrophysical plasmas, e.g., in the atmosphere of neutron star the presence of quantized magnetic field is more common.

New resonances in wave–particle interactions

One of the most characteristic features of relativistic particle dynamics at cyclotron resonances is the stepwise dependence of energy and momentum on time [V. A. Buts and A. G. Zagorodny, Phys. Plasmas 28(2), 022311 (2021)]. The reason for these steps is the phase synchronization of charged particles and waves. To describe other features, we introduce new dependent variables in this paper. These variables allow us to find a convenient representation of the relativistic resonance that fits the numerical results and thus establish new expressions for the stationary phase, as well as analytically describe effects that were previously visible only in numerical experiment. In particular, the temporal width of the steps, the dynamics of particles on the steps, and, most importantly, the moments of random jumps of particles from one step to another are determined. Analysis of the obtained results opens the possibility to find the conditions for the unlimited acceleration of electrons by transverse electromagnetic waves in a vacuum without an external magnetic field.

A novel method to measure small antennas using a wideband coaxial cone TEM cell

AbstractThis paper presents a novel method to measure physically small antennas using a coaxial cone transverse electromagnetic wave (TEM) cell. Due to the ultra‐wideband, large electric field strength, and high dynamic range characteristics, coaxial cone provides a reliable environment to measure parameters such as gain and antenna factor of small antennas. The frequency could cover 200 MHz–40 GHz. To investigate the suitability of the coaxial cone TEM cell to measure antenna, measurements for a wideband small antenna and a horn antenna are carried out. And the validity of this method is verified through comparison of the obtained results, the measurement uncertainty is evaluated. Compared to an anechoic chamber, the space, cost, and time requirements are reduced drastically. Accordingly, this method could be a more effective alternative way to conventional methods such as the three antennas method and the two antennas method using anechoic chambers.

Surface magnon-polaritons at a dielectric/graphene/gyromagnetic interface in a perpendicular applied magnetic field

We present a theoretical study of the surface magnon-polaritons at an interface formed by vacuum and a gyromagnetic medium (that can be either ferromagnetic or antiferromagnetic), when there is a graphene layer deposited between the media at the interface and a magnetic field is applied perpendicular to the interface. The retarded-mode dispersion relations are calculated by considering a superposition of transverse magnetic and transversal electric electromagnetic waves in both media. Our results reveal the appearance of the surface magnon-polariton modes (with frequencies typically of a few GHz) that do not exist in the absence of graphene at the interface. Also, a typical magnon-polariton dispersion relation with damping is revealed, including a resonant frequency that depends on the applied magnetic field. The effects of varying the doping levels, which modify the Fermi energies in the graphene, and varying the perpendicular applied magnetic field are presented, revealing a strong influence exerted by the presence of graphene on the surface magnon-polariton modes. Other effects include the control of the slope of the dispersion curves (with respect to the in-plane wave vector) for the modes as the Fermi energies of the graphene sheet are changed and the distinctive localization properties for the emerging surface modes.

Rod Insertion TDR for Detecting Corrosion Damage in Vertical Grounding Electrodes

Faults in a grounding network pose a serious threat to power system equipment protection and worker safety. A large number of vertical electrodes are used in a grounding network and break-points in these due to soil induced corrosion is one of the prime reasons for faults. We present a rod insertion time domain reflectometry (TDR) technique for vertical grounding electrode break-point detection. A secondary bare rod is inserted adjacent to the grounding electrode while a fast risetime pulse is continuously applied to excite a transverse electromagnetic (TEM) wave that propagates along the rods and reflects back from the break-point. The reflected signals for different depths of the secondary rod are analyzed to identify the location and severity of the break-point. We show that fault detection is possible without prior knowledge of soil electrical parameters. To show the feasibility of the proposed technique, a full wave simulation approach is used to evaluate the wideband input impedance of the grounding and inserted rod system and then FFT is applied to obtain TDR responses. The results show the method is capable of detecting faults for a wide range of soil conductivity for a system bandwidth of 300MHz.

On the mechanism of anomalous phenomena in current-carrying magnetized plasma

The explanation of the mechanisms of anomalous resistance and diffusion of plasma, as well as the generation of fast particles, is given from a unified position on the basis of experimental results obtained in plasma in a magnetically isolated diode of an electron accelerator with a microsecond pulse duration. It is shown that oscillations of the potential and current in plasma with current occur by charge separation and the formation of electric domains with a strong field. Electric domains are generated by means of runaway electrons resulting from the redistribution of the current density and its channelling in the current-carrying plasma. An increase in plasma resistance occurs due to a decrease in the number of electrons in the current-conducting state, since some of the plasma electrons pass into layers of excess negative charge of electric domains. The speed of movement of electrons in the composition of the electric domain is much lower than the velocity of electrons in the conducting state. The nucleation of domains is accompanied by microwave emission. Quasi-neutrals in whole electrical domains are injected into the region of the anode wall. The destruction of domains leads to the appearance of plasma channels between the anode and cathode plasma. The transverse electromagnetic waves generated during the nucleation of domains capture charged particles and inject them in a direction that is perpendicular to the insulating longitudinal magnetic field. Plasma turbulence occurs due to charge separation and the generation of electrical domains that create channels between the plasma and the chamber wall, as well as generating fluxes of fast particles.

Electromagnetoelastic transport through a piezoelectric slab: Selective parity interplay of electromagnetic and acoustic resonances

We present the complete solution concerning to transport properties of coupled transverse electromagnetic and shear acoustic waves propagating via a piezoelectric slab embedded into a homogeneous dielectric medium. Since the electroacoustics of our setup is governed by four electromagnetoelastic eigenmodes, we had to succeed in developing a 4 × 4 transfer matrix method to analytically resolve the problem. As a result, the exact frequency spectra of the transmission, reflection, and transformation transport coefficients were obtained and analyzed in detail for two basic cases where the piezoelectric slab subjected by electromagnetic/acoustic perturbation generates acoustic/electromagnetic response. We establish that wave transformation is effectively realized in vicinities of electromagnetic and acoustic Fabry–Pérot resonances. Surprisingly, as a consequence of the problem geometry and accepted 4 mm symmetry of the piezoelectric medium, the phenomenon of the resonant parity selection arises: in the vicinity of an electromagnetic Fabry–Pérot resonance of the given (odd/even) parity, only acoustic Fabry–Pérot resonances with opposite (even/odd) parity are excited in the coefficient of generation. The piezoelectric coupling vanishes when the parities of both resonances coincide. The changes in transmission and reflection spectra turn out to be more sophisticated. The phenomenon is observed due to quite great distinction between electromagnetic and acoustic wave numbers provided by the fundamental difference between light and sound velocities. In our analysis, particular attention is also paid to the ability of increasing the mutual transformation of electromagnetic and acoustic fluxes.

Electromagnetic-Wave Mechanism of Formation and Propagation of Astrophysical Vortex Jets Generated in the Jumper of a Spiral Galaxy

An explanation of the mechanism of generation and acceleration of jets in outer space is given on the basis of experiments in the physics of electrical discharge. The presence of two arms in the spiral Galaxy gives grounds to assume that they have excess charges of the opposite sign. At the moment when the electric field strength between the tips of the arms becomes sufficient, an electrical breakdown occurs, which is accompanied by the movement of the current-plasma leader in the jumper between the tips of the arms. In the head part of the leader there is a flat electric domain of a strong field, which, during its inception, emits intense transverse electromagnetic waves in a direction perpendicular to the direction of the leader’s motion and to the plane of the accretion disk. The electric domain periodically appears and collapses due to the entry of neutral particles. Transverse electromagnetic waves capture charged particles from the discharge region and accelerate them in the direction of wave propagation. The crossed fields of an electromagnetic wave perform the functions of a multistage accelerator. The acceleration of the particles of the plasma produced in the discharge to relativistic energy values in the region of narrow vortex jets occurs under the action of forces caused by the components of the electromagnetic wave fields and the pressure gradient. The charged particles of a vortex jet acquire a significant rotational moment under the action of the Lorentz force. Explanations of the generation of microwave, bremsstrahlung and optical radiation from the region of the jumper between the arms of the Galaxy in the absence of electrical breakdown are also given.

Asymmetric electric field distribution enhanced hierarchical metamaterials for radar-infrared compatible camouflage

Metamaterials are widely used in electromagnetic radiation and camouflage for their flexible wavefront manipulation and polarization over a broad spectrum ranging from microwaves to optics. However, multispectral compatible camouflage faces significant challenges due to tremendous scale differences of unit cells and desired radiative properties in various spectral regimes. This study assembles a micron-scale infrared emitter, a millimeter-scale microwave absorber, and a metal reflector to propose a hierarchical metamaterial that reduces microwave scattering and reflects low-infrared waves. As a proof of concept, laser etching micro-manufactures an upper infrared shielding layer with a periodic metal pattern. At the same time, bottom square frustum metastructure composites are fabricated and optimized based on genetic algorithms. Under the normal incidence transverse electromagnetic wave with a 90° azimuth angle, the hierarchical strategy and infrared unit create an asymmetric electric field distribution of local near-field coupling, which is conducive to generating additional resonance for broadening the absorption bandwidth. Experiments verify the multispectral camouflage, which shows a high absorption efficiency of more than 90%, ranging from 3.6 to 6.2 and from 8.4 to 18 GHz with a total thickness of 4.05 mm (0.049λmax). Due to the non-reflection of surrounding thermal signals in the infrared 2-22 μm region, low-infrared emissivity (0.29) metamaterials can adapt to various thermal backgrounds. This methodology can provide a novel route for fabricating multispectral camouflage devices.

Two-Material Ridged Substrate Integrated Coaxial Line for Monomode Bandwidth Improvement

The ridged substrate integrated coaxial line (RSICL) supports transverse electromagnetic (TEM) wave with small size, broadband, and good shielding performance. This article presents a two-material RSICL, which has two different dielectric materials filled in its substrate layers. Compared with the conventional RSICL with only one dielectric material, the two-material RSICL shows a higher cutoff frequency of the first higher order mode. Hence, the monomode bandwidth of the two-material RSICL can be improved accordingly. Based on the printed circuit board (PCB) process, the two-material RSICL with feeding structures is designed and fabricated. In the experiment, the first two-order modes of the two-material RSICL are excited with two types of transitions. The measured monomode bandwidth of the two-material RSICL is from dc to 44 GHz, which is 14.9% wider than that of the one-material RSICL.

Features of Transmission and Thermal Losses of Electromagnetic Energy in a Two-Wire Overhead Power Line with the Alternating Electric Current of Conductivity

The results of the research related to the establishment of basic features of transmission and thermal (joule) losses of electromagnetic energy in a homogeneous two-wire overhead power line with the metallic wires of eventual sizes (by the radius of r0 and length l0 &gt;&gt;r0) and alternating (impulsive) electric current of conductivity of i0(t) of different peak-temporal parameters are presented. With the view of the quantum-wave nature of electric current of conductivity of i0(t), it was found that in the metallic wires of probed overhead lines there appear the standing transversal electromagnetic waves (EMWs) that cannot be transmitted at the distance of electromagnetic energy. It is demonstrated that from a weak dispersion of the quantized longitudinal electronic de Broglie semi-waves on the crystal-line lattice sites of a metal (alloy) of wires of the investigated line, the thermal losses of energy are spotted on those lattice sites. The features of the influence of the transversal EMWs in the air envi-ronment of the studied lines on the process of transmission in the overhead power lines at a distance of electro-magnetic energy are established.

Boundary Evaluation of the Maximum Coupling Obtained in EM Illumination Test with Different Polarization Direction

In system-level high-altitude electromagnetic pulse (HEMP) illumination tests, it is common to perform the test in two orthogonal polarizations of the incident electric field. With the judgment standard of the electromagnetic norm, this paper evaluated, improved, generalized, and verified this method. The evaluated result shows that the maximum error of the maximum coupling in this method is less than 3 dB. Meanwhile, this method is improved by serving the 1.2 period of the larger coupling of the 2 illuminations as the maximum coupling. The maximum error can be controlled within 1.5 dB. Moreover, this method is generalized to non-orthogonal conditions. Expressions of the deviations of this method are strictly derived. Based on this method, the application and some extended thinking are discussed. At last, a current coupling test is designed and carried out to verify the methods and conclusions. The methods introduced in this paper can be applied to any linear system in the illumination test under approximate transverse electromagnetic (TEM) waves.

Femtosecond laser-induced sub-wavelength plasma inside dielectrics. II. Second-harmonic generation

Second-harmonic emission at a frequency that is twice the laser frequency is an important diagnostic for nonlinear laser–plasma interaction. It is forbidden for centrosymmetric materials such as the bulk of sapphire. The symmetry, however, can be broken by dielectric discontinuities as a result of plasma generation inside a solid dielectric. In the present work, we explore the basic characteristics of experimentally observed second-harmonic emission during focusing a femtosecond Bessel beam inside sapphire. We employ three-dimensional particle-in-cell simulations and the Helmholtz wave equation for theoretical investigations. We analyze how the efficiency of second-harmonic generation and its polarization depend on the plasma parameters. We find that the second-harmonic is generated either due to the coalescence of two-surface electromagnetic waves or nonlinear interaction between the transverse electromagnetic wave and the longitudinal electron plasma wave driven by linear mode conversion. Experimental results agree with the theoretical predictions and confirm the existence of over-critical plasma inside the sapphire that is essential for the resonance of plasma waves or excitation of surface plasmons.

The circularly bent split ring resonator with a high effective medium ratio for multi frequency satellite band applications

The scattering parameter for the interaction with the electromagnetic wave is introduced the interesting properties of the effective parameter. The compactness of the subwavelength based metal-dielectric based resonator is related to the tailored metallic design. In this research work, two circular bent split ring resonator is represented with four resonant frequencies for S, C band applications. This subwavelength based metamaterial resonator exhibit the bandwidth from 1.97 to 2.11, 3.43–3.63, 5.31–5.46, 8.3–8.6 GHz at 2.03, 3.57, 5.37, 8.47 GHz, respectively. The geometric specification, equivalent circuit model, design selection process are included to observe the electromagnetic characteristics, and the electric field, magnetic field and surface current distribution are used to analyse the state of polarisation at different resonant frequencies for the applied transverse electromagnetic wave. In parametric analysis, the relative angular rotation of two bent circular split resonators expresses the effect of the metallic layer with the rearrangement of the gap between the conducting layers. Moreover, different substrate materials with a change in thickness are analysed to characterize the scattering properties for different dielectric constants.