Transverse Electromagnetic Waves Research Articles

Eigenwaves in a two-component system of particles with nonzero magnetic moments

Two-component systems of particles with nonzero intrinsic magnetic moments are shown to support not only the transverse electromagnetic and longitudinal waves, but also self-consistent spin waves and waves that propagate independently in each component and degenerate into oscillations for spin-zero systems. For all types of waves, the dispersion relations are obtained by solving the quantum hydrodynamics equations and field equations in linear approximation.

Nonlinear generation mechanism for the vortical electric field in magnetized plasma media

A physical mechanism and nonlinear mathematical formalism for study of generation and further amplification of the vortical electric field in the magnetized plasma are proposed. A modulation instability process in a plasma medium is considered in a strong constant magnetic field. The plasmon condensate is modulated not by a low-frequency ionic sound as is usually done, but by the beating of two high-frequency transverse electromagnetic waves propagating along the external magnetic field. Conditions in which aperiodic instability occurs are found and its increment is defined. This instability leads to a decrease in the scale of Langmuir turbulence along the external magnetic field and to the generation of electromagnetic fields. Dissipative property of the medium increases an amplitude threshold of the pumping waves. It is shown that for sufficiently large amplitudes of pumping waves the effect described in the paper is the defining nonlinear process.

Interaction of transverse electromagnetic waves with counterpropagating surface waves at a plasma-dielectric interface

The nonlinear interaction of high-frequency transverse electromagnetic waves normally incident from a plasma region on to a dielectric with two surface waves (SWs) propagating in the opposite directions along the interface is studied. This interaction is found to be stable causing a slight modulation to the SWs in contrast to the decay instability for longitudinal plasma waves. The corresponding nonlinear frequency shift of the SWs is obtained and analyzed.

Transverse Wave Propagation in Relativistic Two-Fluid Plasmas around Reissner–Nordström Black Hole

We investigate transverse electromagnetic waves propagating in a plasma influenced by the gravitational field of the Reissner–Nordstrom black hole. Applying 3+1 spacetime split we reformulate the relativistic two-fluid equations to take account of gravitational effects due to the event horizon and describe the set of simultaneous linear equations for the perturbations. Using a local approximation we investigate the one-dimensional radial propagation of Alfven and high frequency electromagnetic waves. We derive the dispersion relation for these waves and solve it for the wave number k numerically.

Guiding, Focusing, and Sensing on the Subwavelength Scale Using Metallic Wire Arrays

We show that tapered arrays of thin metallic wires can manipulate electromagnetic fields on the subwavelength spatial scale. Two types of nanoscale imaging applications using terahertz and midinfrared waves are enabled: image magnification and radiation focusing. First, the tapered wire array acts as a multipixel TEM endoscope by capturing an electromagnetic field profile created by deeply subwavelength objects at the endoscope's tip and magnifying it for observation. Second, the image of a large mask at the endoscope's base is projected onto a much smaller image at the tip.

Numerical investigation of the surface impedance of ferromagnetic manganite thin films

The surface impedance and the microwave characteristics of conductive ferromagnetic (FM) films with the parameters similar to those of La 0.7Sr 0.3MnO 3 (LSMO) films deposited on a dielectric substrate were modeled with respect to linearly polarized planar transverse electromagnetic waves, incident normally to the structure. It was shown that the microwave losses caused by the film conductivity dominate the losses due to the ferromagnetic resonance (FMR) if the film is thin enough. The FMR is more clearly observed in FM films deposited on substrates of higher permittivity due to smaller microwave losses, caused by the film conductivity in this case. The peculiarities of the surface impedance and the absorption, reflection and transmission coefficients caused by the film conductivity and FMR are simultaneously observed in thicker films.

On the theory of self-modulation instability in an FEL amplifier due to stimulated scattering of counterpropagating waves

We present the results of numerical simulation of the self-modulation processes in an amplifier based on the effect of stimulated scattering of two counterpropagating transverse electromagnetic waves by a relativistic electron beam (FEL amplifier). Two models of the studied system are considered. One model allows for the effects of overbunching of electrons and is based on the modified method of macroparticles. The other is a simplified wave model obtained in the approximation that the amplitude of a combination wave is small if the nonlinearity of the electron-beam processes is negligibly small. The mechanisms of self-modulation are studied. The scenarios of transition to chaos, observed with increase in the input-signal intensity and system length, are examined.

Resonant transition radiation of solar radio bursts

We calculate the resonant transition radiation (RTR) using the most general formulas and obtain approximate analytical expressions describing the RTR dependence on the fast-particle velocity and magnetic-field intensity. Dependence of the RTR on the angle between the wave vector and the magnetic-field direction and also on the thermal velocity of background-plasma electrons is considered on the basis of approximate expressions for RTR, in which the longitudinal dielectric permittivity of the plasma is written neglecting the wave vector of transverse electromagnetic waves. The obtained dependences are combined into unified expressions for RTR coefficients. Comparison with the earlier found RTR coefficients is performed. It is shown that the obtained coefficients correspond better to the nature of the resonant transition radiation. Finally, the obtained RTR coefficients are used for interpretation of the radio emission of the solar burst of December 24, 1991.

Application of the averaging method to calculation of propagation of electromagnetic radiation through thin films with different conductivities

The averaging method is used for calculation of the reflection and transmission coefficients of a 1D longitudinal electromagnetic wave and a 1D transverse electromagnetic wave that are incident along the normal onto a plane-parallel plate. The averaged electrodynamic boundary conditions are derived for an arbitrary conductivity of the plate. It is demonstrated that the averaging method enables one to simplify the calculations and resulting expressions owing to a decrease in the order of the system of equations and elimination of trigonometric functions. The error of this method is several percent for planes with thicknesses up to 0.35 of the wavelength in the medium.

Superluminal electromagnetic waves in pulsar winds

Using a combination of analytical methods and Particle-In-Cell (PIC) simulations, we discuss the properties of a coherent, nonlinear, electromagnetic wave propagating in a neutron star wind. For the specific case of the Crab, the canonical flow parameters are such that a circularly polarised, transverse electromagnetic (TEM) wave will undergo a transition from subluminal to superluminal propagation between the inner and outer wind regions, which might involve radiative dissipation. As the superluminal wave encounters the wind’s termination shock, it locally affects the state of the hot, radiative plasma in the shock interior and the downstream medium, possibly with an observable signature. PIC simulations indicate that the wave ultimately decays after some 10 2−10 3 plasma skin depths; i.e., over an angular scale of up to 0.05″ for the Crab. To complement our simulations, we solve generalised Rankine–Hugoniot shock jump conditions for a plasma carrying a coherent TEM wave, for a broad range of plasma and wave parameters.

Multiple harmonic plasma emission

A generalized weak turbulence theory for electromagnetic emission at multiple harmonics of the plasma frequency is developed. In the literature, the electromagnetic emission at the plasma frequency and/or its second harmonic has been intensively studied. However, the emission at harmonics higher than the second harmonic is scarcely discussed. In the present paper, the higher harmonic plasma emission is explained by taking the interactions between the transverse mode and electrostatic nonlinear eigenmodes into consideration. The present analysis incorporates electrostatic nonlinear harmonic Langmuir waves into the fully electromagnetic weak turbulence formalism recently reformulated on the basis of the statistical mechanical Klimontovich approach. The wave kinetic equations for the transverse electromagnetic and Langmuir waves interacting with the harmonic Langmuir waves are derived, on the basis of which the emission of electromagnetic waves near multiple harmonics of the plasma frequency is qualitatively discussed.

The effects of thermal velocities on frequency spectra of an unbounded collisionless degenerate plasma with two different types of equilibrium distribution functions

The thermal effects on the frequency spectra and damping decrements of the waves propagating in a plasma of two nonisothermal different types of degenerate and nondegenerate charge carriers are investigated. This is done by obtaining the Fourier transform of the transverse dielectric tensor elements of an unbounded collisionless warm degenerate plasma. It is shown that in a warm degenerate plasma, static Debye screening of the very slow low-frequency longitudinal waves is changed. Furthermore, it is shown that the skin effect of the transverse electromagnetic waves is related to the Landau damping.

Molecular dynamics study of the greenhouse gases clusterization

Absorption of CO2, CH4 and N2O molecules by water clusters has been investigated by the molecular dynamics method. The frequency spectra of dielectric permittivity for systems consisting of (H2O) n , (CO2) i (H2O)10, (CH4) i (H2O)10 and the (N2O) i (H2O)10 clusters have been defined. The calculation and analysis of IR radiation absorption spectra for these systems have been carried out. The analysis of inharmoniousness of phonon oscillations allows an explanation of the origin of characteristic frequencies appearing in the IR spectra. The influence of cluster compositions on the reflection coefficient of transverse electromagnetic wave from the cluster surface was considered. The capture of greenhouse gas molecules by an ultra disperse aqueous medium reduces the ability of the medium to absorb the Earth's radiation and thus reduces the greenhouse effect.

Application of finite-difference time domain to dye-sensitized solar cells: The effect of nanotube-array negative electrode dimensions on light absorption

We examine the light absorbing behavior of dye-sensitized solar cells (DSCs) having cathodes (negative electrodes) comprised of highly ordered TiO 2 nanotube arrays using the electromagnetic computational technique, finite-difference time domain (FDTD). The highly ordered nanotube arrays, grown using anodic oxidation of titanium foils or thin films, feature an open end with the other end fixed on a dense oxide layer (barrier layer). The numerical simulation model is comprised of nanotube arrays on a transparent conducting glass substrate under front-side illumination. In the FDTD analysis, a transverse electromagnetic (TEM) wave is incident onto a N719 dye-coated nanotube array initially passing through the barrier layer; light that emerges from the nanotubes is reflected by a perfectly conducting layer (perfect electric conductor—PEC) boundary that simulates the effect of the DSC platinum counter electrode. An observation plane placed between the electromagnetic source and DSC detects the intensity of both the incident wave and the wave returning back from the DSC structure. The absorbance and transmittance spectra are determined in the wavelength range 300–700 nm as a function of nanotube-array dimensions including length, pore size, barrier layer thickness, and surface roughness while keeping the wall thickness constant at 12 nm. The validity of the computational simulations is experimentally verified. A significant increase in the light absorption by the dye-coated nanotubes was observed for increasing nanotube length; smaller pore sizes, and increased surface roughness. Changes in the barrier layer thickness had a negligible effect on the absorbance spectrum. Our efforts demonstrate FDTD to be a broadly applicable technique capable of guiding design of an optimal DSC architecture.

Nonlinear mechanism for the generation of electromagnetic fields in a magnetized plasma by the beatings of waves

The modulational instability in a plasma in a strong constant external magnetic field is considered. The plasmon condensate is modulated not by conventional low-frequency ion sound but by the beatings of two high-frequency transverse electromagnetic waves propagating along the magnetic field. The instability reduces the spatial scales of Langmuir turbulence along the external magnetic field and generates electromagnetic fields. It is shown that, for a pump wave with a sufficiently large amplitude, the effect described in the present paper can be a dominant nonlinear process.

Calculation of transverse waves in a shielded transmission line containing circular cylindrical conductors

A method is proposed for calculating a shielded homogeneous multiconductor transmission line containing conductors of circular cross section. Formulas are obtained for the matrix of the conductor capacitance per unit length and the electric parameters of transverse electromagnetic waves.

Simultaneous localization of photons and phonons in two-dimensional periodic structures

We demonstrate theoretically the simultaneous localization of photons and phonons in the same spatial region by introducing lattice defects in a periodic array of dielectric/elastic material that exhibits gaps for both electromagnetic and elastic waves. Transverse electromagnetic waves, pure shear elastic waves, and mixed shear and dilatation elastic waves were simultaneously localized. The coexistent localization of light and sound can have a strong influence on photon-phonon interactions (i.e., optical cooling) and the possibility of dual acoustic-optical devices that can integrate the management of sound, heat, and light.

Theory of transverse surface electromagnetic waves propagating along a plasma-metal boundary with a finite radius of curvature in a magnetic field

The spectra of electromagnetic waves propagating perpendicular to the axis of a plasma-filled metal waveguide in a magnetic field are studied with allowance for the effects exerted upon the wave frequency by the radial plasma density variation and by the emission of waves through a narrow axial slit in a waveguide wall. The case of wave propagation along the boundary between a plasma and a cylindrical metal waveguide wall with a periodically varying radius of curvature is also considered. The electromagnetic properties of the plasma are described by a dielectric tensor in the hydrodynamic approximation. The spatial distribution of the wave field is determined by the method of successive approximations. Results are presented from both analytical and numerical investigations. Analytical expressions for the corrections to the wave frequency due to the emission of the wave energy from the waveguide and due to the slight corrugation of the waveguide wall are obtained. The rates of wave damping due to the emission of the wave energy through a narrow axial slit and due to collisions between the plasma particles are found. The correction to the frequency that comes from the periodic variation of the radius of curvature of the plasma surface is calculated to within terms proportional to the square of the small parameter describing the azimuthal corrugation of the waveguide wall. The effect of the radial plasma density variation on the dispersion of the surface modes is examined both analytically and numerically.

General dynamic equations of electromagnetomechanics for dielectrics and piezoelectrics

A new principle is proposed for constructing a theory of dynamic coupled electromagnetomechanical processes in dielectrics and piezoelectrics. It is based on the purely mechanical two-continuum description of the deformation of dielectrics as a mixture of neutral molecules each formed of bound positive and negative charges. Based on the definition of a polarization vector and associated electric field, the mechanics equations are transformed into coupled equations for the displacements of neutral molecules and electric-field strength. These equations, invariant under the Galilean transformation, describe longitudinal electric and transverse electromagnetic dispersed waves in moving dielectrics as well as coupled acoustic and electromagnetic waves in dielectrics and piezoelectrics. From these equations Maxwell’s equations and the acoustic approximation in electroelasticity for piezoelectrics follow as particular cases. Under this theory, the ether is modeled as a dielectric that is a nearly perfect fluid in which heavenly bodies freely move and transverse electromagnetic waves propagate as mutual displacements of the positive and negative charges of neutral particles that form the ether. Such a model makes it possible to uniquely explain, within the framework of classical physics, the fundamental experiments due to Fizeau, Michelson, Miller, and Galaev, stellar aberration, and the rotational experiments, which point to the fact that the ether exists

A survey of mode-conversion transparency windows between external electromagnetic waves and electron Bernstein waves for various plasma slab boundaries

For the plasma slab boundary with monotonically increasing density profile along the x axis and the magnetic field along the z axis, both Nz and Ny components of the refractive index are parallel to the plasma slab and are conserved in the mode-conversion process between the vacuum transverse electromagnetic (TEM) waves and the electron Bernstein (B) waves. Information of Nz and Ny is sufficient to identify the waves uniquely both for TEM waves and B waves coupled by mode conversion. Furthermore, the wave differential equation which governs the mode-conversion process can be written in the normalized form with a few numbers of the normalized parameters and variables for the linear density profile. Thus, the mode-conversion transparency window, which is presented as a contour plot of the mode-conversion rate versus the Nz–Ny plane, can be categorized for the pair of parameters of the density scale length normalized to the wavelength in vacuum Ln/λ0 and the frequency to the cyclotron frequency ω/Ω.A survey of the transparency windows for various parameter ranges of Ln/λ0 and ω/Ω is presented. The windows are categorized into four types. The frosted type at the steepest density gradient region has a broad transparency profile but even the peak is not completely transparent. The perpendicular-X type at the next steep density gradient region also has a broad transparency profile with a completely transparent peak by the perpendicularly propagating extraordinary waves. The OXB type at the gentle density gradient region has a pair of completely transparent sharp peaks by the obliquely propagating ordinary waves at the optimal propagation angles with Nz = ±N∥opt and Ny = 0. The fourth is the g1 type in the intermediate density gradient region between the above two cases, which has two completely transparent peaks in the window. Finally, a simulation to examine the applicability of the survey to experiments is made using a test density profile, which elucidates key points for the application of the survey.