Electromagnetic Field Components Research Articles

A Time-Domain Propagator Numerical Method for Computational Electromagnetics

A new time-domain numerical method for full-wave electromagnetic scattering and propagation is presented. The propagator method can be described as a numerical integral operator technique for moving the electromagnetic field through numerical space at successive increments in time. The numerical equations are obtained by discretizing electric and magnetic field propagator integrals. A primary feature of the propagator method is that all six electromagnetic-field components are calculated at each numerical grid point and all components are in time synchronization. Constant spatial and time increments are maintained throughout an inhomogeneous numerical space by employing an extrapolation procedure that ensures causality. A simple and effective first-order absorbing boundary condition, described as the null boundary condition, is introduced. Examples, provided in one-, two-, and three-dimensions, include plane wave reflection from and transmission through a planar boundary, and scattering and radar cross sections for canonical dielectric objects.

Near-field open coaxial sensor. Measurement aperture spatial resolution ability evaluation

Microwave sensors find wider and wider application in the different domain. The sensors design became more complicated, the methods of their description became more exact.The paper presents a simplified model for describing the near field of a coaxial sensor. There was given grounding of analytical solution simplification, considered fields components in the working area and analyzed field in the working area distribution. The results of a comparison of the distributions of the electromagnetic field components near the aperture are shown, obtained on the basis of a rigorous and simplified model. The field intrusion into the sample at first approximation corresponds to radial distribution. The spatial resolving ability of the sensor, both along the radius and the depth of the sample, is determined by the diameter of the central conductor or by the size of the slit. By varying the shape of the aperture, it is possible to change the characteristics of the sensor, optimally selecting them for a priori known properties of the sample.

Nonstationary processes of acousto-electromagnetic emission of the lithosphere in a seismic active region resulted from surface and borehole measurements

The results of synchronous detection of the emission of various components of the electromagnetic and acoustic fields obtained under conditions of low industrial interference and a high level of microseismicity are investigated. To compensate electromagnetic radiation of lithospheric origin, a compensation method was used. The signal loop antenna, recording a mixture of signals of lithospheric and atmospheric-thunderstorm origins, was used as a magnetic core of a steel casing of the borehole. The compensating signal was recorded using an antenna, the receiving coil of which was identical to the coil of the signal antenna. The measurements were carried out in the seismically active region of Russia (the Kamchatka peninsula, the Paratun hydrothermal deposit) at the intersection of the sublatitudinal and submeridional fault zones. Methods for analyzing registration data of non-stationary processes are considered using the example of acoustic-electromagnetic emission of the lithosphere, the electromagnetic component of which is a component of the natural electromagnetic field of the Earth. Their characteristics are estimated and a statistical model is proposed that uses nested semi-Markov processes and finite atomic functions. Observations of geophysical electromagnetic fields, in addition to useful information about the emission processes, contain interference, mainly of technogenic origin. They are especially strong in downhole measurements when a well casing is used as the receiving antenna. These interferences significantly impede the allocation of useful information. The possibility of using bleaching filters to increase the contrast of observation of useful signals of lithospheric origin against their background is considered.

COMPARISON AND ANALYSIS OF THE EFFECTIVE OBSERVATION AREA OF THE TENSOR CSAMT BY NUMERICAL MODELING

AbstractAccording to the response formulas of the scalar CSAMT (controlled source audio‐frequency magnetotelluric) method, its programs can be designed in several manners with different sources such as a vertical double dipole source and a three‐dipole source of varied geometries. Through numerical simulation, this study obtains the value distributions of X‐ and Y‐direction components of the resultant electromagnetic (EM) field, which permit to further analyze the effective observational area. The results show that the distribution of crosslike source exhibits scattered weak responses, representing a smaller effective observational zone. Meanwhile, its requirement to the terrain condition of the working site is very harsh, thus cannot work well in mountainous areas with high topographic relief. Based on the principle of the rotating three‐dipole device, we propose a new device composed of multiple dipole sources for the CSAMT which can facilitate integrated measurement of tensors of the EM field. Compared with the cross‐like source, this approach can realize measurement throughout the whole area without weak‐value zones. Moreover, this new device is easy to deploy in various terrains. The results of this study provide a technical basis for further engineering production of tensor measurement.

Mathematical modelling of RF plasma flow at low pressure with electrodynamics

The mathematical model of the RF plasma at low pressure in both free-molecule and transition flow at Knudsen 0.03 ≤ Kn ≤ 3 is described. The model is based on the statistical approach for the neutral component of the plasma together with the continuum model for electron, electromagnetic field and metastable components. Results of plasma flow parameters calculations and testing results of electric field calculations are presented.

Electro-magnetic interpretation of four-element torus

The concept of the memristor was proposed by Leon Chua in 1971, along with some electro-magnetic interpretations according to quasi-static expansion of Maxwell’s equations. In 2003, Chua included the memristor into a four-element torus that has infinite circuit elements. This paper uses the quasi-static method to interpret every circuit element in the torus. Two examples are also provided to show how topologic structure of an element affects its electrical properties by affecting the dominant electro-magnetic field components. Additionally, it is proved that the circuit elements in the torus, except the resistive, capacitive and inductive elements, cannot exist independently. Moreover, the incorrectness in Chua’s interpretation of the memristor, that the memristor cannot be interpreted with the transient quasi-static method due to its memory property, is pointed out. Finally, the limitations of the electro-magnetic interpretation method are discussed.

Analytic model for electromagnetic fields in the bubble regime of plasma wakefield in non-uniform plasmas

Based on a model of plasma wakefield in the strongly nonlinear (bubble) regime, we develop a lowest-order perturbation theory for the components of electromagnetic fields inside and outside the bubble using the assumption of small thickness of the electron sheath on the boundary of the bubble. Unlike previous models, we derive simple explicit expressions for the components of electromagnetic fields not only in the vicinity of the center of the bubble, but in the whole volume of the bubble (including the areas of driving or accelerated bunches) as well as outside it. Moreover, we apply the results to the case of radially non-uniform plasma and, in particular, to plasma with a hollow channel. The obtained results are verified with 3D particle-in-cell simulations which show a good correspondence to our model.

A novel perturbation theory describes electromagnetic field components in a bubble regime of plasma wakefield

Theoretical physicists present their novel perturbation theory that focuses on electromagnetic fields in the bubble regime of wakefield.

Old cities environment transformation in the conditions of modern technogenic influence (ecological analysis of Kimry, Tver Region)

The following paper deals with the problem of historic cultural centers environment transformation on the example of Kimry, the Tver Region. The relevance of the research is defined by the fact that technogenic influence of all environment components on urban areas is actually big. The dense population, abundance of multi-storey residential buildings and social objects are combined with intensive traffic flows, existence of the household and industrial enterprises emanated considerable technogenic flows of toxic substances. The paper contains results of a complex analysis of Kimry ecological state, including assessment of soil cover and atmospheric air pollution, magnetic component of technogenic electromagnetic fields of industrial frequency, air aero ionic composition and acoustic influences. The authors show that the maximum technogenic transformation of environmental material and geophysical components is characteristic for the Kimry central part where difficult infrastructure of the modern city is inscribed in tight space of the historic center. Pollution of soil cover and atmospheric air are due to high concentration of transport and imperfection of highways network. Universal existence of electromagnetic smog and change of air aero ionic composition are caused by low layout of city lighting and electrical power supply networks wiring. As a result the authors offer a number of ways how to improve the ecological situation. Division of business parts and cultural parts of old cities and creation of recreational and tourist clusters in the cultural part could be a cardinal solution of the historic centers problem.

Photoinactivation related dynamics of ctenophore photoproteins: Insights from molecular dynamics simulation under electric-field

Photoinactivation is a common phenomenon in bioluminescence ctenophore photoproteins (e.g mnemiopsin, berovin and BfosPP) with still unknown mechanism. The activity of coelenterate photoproteins (e.g aequorin), which has high structural similarity with ctenophore photoproteins, is not affected by light. Recently, we have characterized the effects of light on ctenophore photoprotein mnemiopsin, in different conformations, which has demonstrated light induced structural changes, uniquely secondary structures, of both apo and holo mnemiopsin. This paper is further expansion of our previous work, by applying molecular dynamics simulations to investigate photoinactivation related dynamics of berovin at atomistic level, in comparison with aequorin, under the influence of electric component of electromagnetic field. The results have indicated that the intense electric filed could influence structure of both berovin and aequorin but in different manner, whereas moderate electric field only effects on berovin's structure remarkably. In this case, increased helicity of residues E180-M193 and decreased helical contents of L38-D46 and L125-D138 segments are considerable in berovin as well as flexibility elevation of calcium binding loops. These changes cause structural expansion of berovin, especially at N-terminal domain, in direction of electric field. In conclusion, the induced structural changes of mentioned helical parts together with elevated fluctuation of their adjacent segments, N26-D46 and M193-Y206, indicate the influence of light on substrate stabilizing residues, Arg41 and Y204. This condition could presumably leads to inactivation of bioluminescence reaction due to separation of substrate from the cavity of the protein.

Effects of ferrite coating layer on PEMC sphere radar cross section

Characteristics of Radar Cross Sections (RCS) in the presence of ferrite coating layer on perfect electromagnetic conductor sphere have been studied theoretically and analytically. Spherical wave vector functions were used to expand the incident, scattered and transmitted electromagnetic field components. Co and Cross polarized scattered field components have been evaluated by applying PEMC boundary conditions at both interfaces, i.e., free space- ferrite layer and at ferrite layer-PEMC sphere core. By using obtained values of the Co and Cross polarized scattering coefficients, the forward and backscattered Radar Cross Section were calculated and compared with already published literature. The effects of applied dc bias magnetic field, saturation magnetization, incident frequency, sphere radius and relative permittivity on forward and backscattered radar cross section were analyzed in graphical form.

Response of complementary split ring resonators in composite stratified substrate integrated waveguide

In this work, the behavior of a Complementary Split Ring Resonator (CSRR) operating within the quasi-static resonance regime and embedded in a composite stratified Substrate Integrated Waveguide (SIW) with two different dielectric layers is analyzed. In these conditions, the propagating modes within the SIW combined with the imposed non-symmetrical structure lead to the excitation of the CSRR elements inside the SIW at difference with conventional excitation. Several cases of CSRR loaded SIW are proposed, and their electromagnetic field components as well as their frequency response are analyzed, providing insight into the CSRR resonance excitation. A test prototype has been designed, fabricated, and measured, showing a good agreement with simulation results and providing a new alternative for the implementation of compact frequency selective devices compatible with planar technology and without undesired radiation loss.

Discontinuities in the electromagnetic fields of vortex beams in the complex source-sink model

An analytical discontinuity is reported in what was thought to be the discontinuity-free exact nonparaxial vortex beam phasor obtained within the complex source/sink model. This discontinuity appears for all odd values of the orbital angular momentum mode. Such discontinuities in the phasor lead to nonphysical discontinuities in the real electromagnetic field components. We identify the source of the discontinuities, and provide graphical evidence of the discontinuous real electric fields for the first and third orbital angular momentum modes. A simple means of avoiding these discontinuities is presented.

On Unified Numerical Algorithm for 3-D Scattering From Dielectric and PEC Random Rough Surfaces

We present a unified fast scattering algorithm for dielectric random rough surfaces that asymptotically reduces to the perfect electric conductor (PEC) case when the loss tangent grows extremely large. The Coifman wavelets are employed to implement Galerkin’s procedure in the method of moments (MoM). The Coiflets-based surface integral equations (IEs) consist of both the tangential and normal components of electromagnetic fields as unknowns. The inherited mathematical superiority, e.g., local multiresolution analysis and high regularity with Holder index 1.449 in smoothness, allows efficiently implementing both electric field IE and magnetic field IE. Due to the high-precision one-point quadrature, the Coiflets yield fast evaluations of the most off-diagonal entries, reducing the matrix fill effort from O(N2) to O(N). The orthogonality and Riesz basis of the Coiflets generate well-conditioned impedance matrix, with rapid convergence for the conjugate gradient solver. In addition, a semianalytical expression of the tapered-wave carried power is derived, which speeds up computations of the normalization factor of scattering coefficients. Numerical results demonstrate that the reduced PEC model does not suffer from ill-posed problems, namely, matrix condition numbers are kept small and solutions are stable under extremely large loss tangent, where normal components of $H$ -field and tangential $E$ -field have vanished. Compared with the previous publications and laboratory measurements, good agreement is observed.

Modeling of Antenna for Deep Target Hydrocarbon Exploration

Nowadays control source electromagnetic method is used for offshore hydrocarbon exploration. Hydrocarbon detection in sea bed logging (SBL) is a very challenging task for deep target hydrocarbon reservoir. Response of electromagnetic (EM) field from marine environment is very low and it is very difficult to predict deep target reservoir below 2km from the sea floor. This work premise deals with modeling of new antenna for deep water deep target hydrocarbon exploration. Conventional and new EM antennas at 0.125Hz frequency are used in modeling for the detection of deep target hydrocarbon reservoir. The proposed area of the seabed model (40km ´ 40km) was simulated by using CST (computer simulation technology) EM studio based on Finite Integration Method (FIM). Electromagnetic field components were compared at 500m target depth and it was concluded that Ex and Hz components shows better resistivity contrast. Comparison of conventional and new antenna for different target depths was done in our proposed model. From the results, it was observed that conventional antenna at 0.125Hz shows 70% ,86% resistivity contrast at target depth of 1000m where as new antenna showed 329%, 355% resistivity contrast at the same target depth for Ex and Hz field respectively. It was also investigated that at frequency of0.125Hz, new antenna gave 46% better delineation of hydrocarbon at 4000m target depth. This is due to focusing of electromagnetic waves by using new antenna. New antenna design gave 125% more extra depth than straight antenna for deep target hydrocarbon detection. Numerical modeling for straight and new antenna was also done to know general equation for electromagnetic field behavior with target depth. From this numerical model it was speculated that this new antenna can detect up to 4.5 km target depth. This new EM antenna may open new frontiers for oil and gas industry for the detection of deep target hydrocarbon reservoir (HC)

Near-field spectroscopic properties of complementary gold nanostructures: applicability of Babinet's principle in the optical region.

We examine the far-field and near-field properties of complementary screens made of nanostructured gold thin films, a rectangular nanowire and a nanovoid, using an aperture-type scanning near-field optical microscope and electromagnetic field calculations, and discuss the applicability of Babinet's principle in the optical region. The far-field transmission spectra of the complementary screens are considerably different from each other. On the other hand, genuine near-field extinction spectra exhibit nearly complementary characteristics. The spatial features of the observed near-field images for the complementary screens show little correlation. We have found from the Fourier analysis of the simulated images that high spatial-frequency components of the electromagnetic fields show mutual spatial correlation. These results suggest that Babinet's principle is applicable to the high spatial-frequency components of electromagnetic fields for the complementary screens.

Effects of phase conjugation on electromagnetic optical fields propagating in free space

By using the property of phase conjugation, we demonstrate that the inverse of van Cittert–Zernike theorem holds for electromagnetic (EM) fields propagating in free space. This essentially implies that spatially incoherent partially polarized field distributions can be generated from spatially coherent partially polarized optical fields. We further utilize phase conjugation with a polarization rotator to swap the spatial coherence properties of orthogonal polarization components of EM fields on propagation, at least in free space. This study suggests that the method of phase conjugation could be potentially useful in arbitrarily manipulating spatial coherence properties of vector optical fields in the field plane.

The substantial model of the photon

It is shown that the angular frequency of the photon is nothing else than the averaged angular frequency of revolution of the electron cloud’s center during emission and quantum transition between two energy levels in an atom. On assumption that the photon consists of charged particles of the vacuum field (of praons), the substantial model of a photon is constructed. Praons move inside the photon in the same way as they must move in the electromagnetic field of the emitting electron, while internal periodic wave structure is formed inside the photon. The properties of praons, including their mass, charge and speed, are derived in the framework of the theory of infinite nesting of matter. At the same time, praons are part of nucleons and leptons just as nucleons are the basis of neutron stars and the matter of ordinary stars and planets. With the help of the Lorentz transformations, which correlate the laboratory reference frame and the reference frame, co-moving with the praons inside the photon, transformation of the electromagnetic field components is performed. This allows us to calculate the longitudinal magnetic field and magnetic dipole moment of the photon, and to understand the relation between the transverse components of the electric and magnetic fields, connected by a coefficient in the form of the speed of light. The total rest mass of the particles making up the photon is found, it turns out to be inversely proportional to the nuclear charge number of the hydrogen-like atom, which emits the photon.

Electromagnetic scattering by multiple dielectric particles under the illumination of unpolarized high-order Bessel vortex beam

This study investigates the electromagnetic scattering of a high-order Bessel vortex beam by multiple dielectric particles of arbitrary shape based on the surface integral equation (SIE) method. In Cartesian coordinates, the mathematical formulas are given for characterizing the electromagnetic field components of an arbitrarily incident high-order Bessel vortex beam. By using the SIE, a numerical scheme is formulated to find solutions for characterizing the electromagnetic scattering by multiple homogeneous particles of arbitrary shape and a home-made FORTRAN program is written. The presented theoretical derivations as well as the home-made program are validated by comparing to the scattering results of a Zero-Order Bessel Beam by the Generalized Lorenz-Mie theory. From our simulations, the beam’s order, half-cone angles, and the ways of particles’ arrangement have a great influence upon the differential scattering cross section (DSCS) for multiple particles. Furthermore, for a better understanding of the scattering characteristic in three dimension (3-D) space, the 3-D distribution of the DSCS for different cases is presented. It is anticipated that these results can be helpful to understand the scattering mechanisms of a high-order Bessel vortex beam on multiple dielectric particles of arbitrary shape.

IShTAR ICRF antenna field characterization in vacuum and plasma by using probe diagnostic

RF sheath physics is one of the key topics relevant for improvements of ICRF heating systems, which are present on nearly all modern magnetic fusion machines. This paper introduces developement and validation of a new approach to understanding general RF sheath physics. The presumed reason of enhanced plasma-antenna interactions, parallel electric field, is not measured directly, but proposed to be obtained from simulations in COMSOL Multiphysics® Modeling Software. Measurements of RF magnetic field components with B-dot probes are done on a linear device IShTAR (Ion cyclotron Sheath Test ARrangement) and then compared to simulations. Good resulting accordance is suggested to be the criterion for trustworthiness of parallel electric field estimation as a component of electromagnetic field in modeling. A comparison between simulation and experiment for one magnetic field component in vacuum has demonstrated a close match. An additional complication to this ICRF antenna field characterization study is imposed by the helicon antenna which is used as a plasma ignition tool in the test arrangement. The plasma case, in contrast to the vacuum case, must be approached carefully, since the overlapping of ICRF antenna and helicon antenna fields occurs. Distinguishing of the two fields is done by an analysis of correlation between measurements with both antennas together and with each one separately.