Transverse Electromagnetic Waves Research Articles

Instabilities of a circularly polarized wave with trapped particles in an isotropic plasma

The structure and stability of a transverse electromagnetic wave propagating with a velocity lower than the speed of light in an unmagnetized plasma are considered. The stationary finite-amplitude wave is described by exact solutions to the Vlasov-Maxwell equations. However, unlike the well-known electrostatic analog, the Bernstein-Greene-Kruskal wave, the wave structure is determined to a large extent by the presence of trapped particles with a shear of transverse velocities, without which the existence of waves with a refraction index larger than unity is impossible. It is shown that the main origin of the wave instability is the longitudinal motion of trapped particles relative to the background plasma. Expressions for the growth rates in the main instability regimes are found under definite restrictions on the wave parameters.

Generating High-Power Short Terahertz Electromagnetic Pulses with a Multifoil Radiator

We describe a multifoil cone radiator capable of generating high-field short terahertz pulses using short electron bunches. Round flat conducting foil plates with successively decreasing radii are stacked, forming a truncated cone with the z axis. The gaps between the foil plates are equal and filled with some dielectric (or vacuum). A short relativistic electron bunch propagates along the z axis. At sufficiently high particle energy, the energy losses and multiple scattering do not change the bunch shape significantly. When passing by each gap between the foil plates, the electron bunch emits some energy into the gap. Then, the radiation pulses propagate radially outward. For transverse electromagnetic waves with a longitudinal (along the z axis) electric field and an azimuthal magnetic field, there is no dispersion in these radial lines; therefore, the radiation pulses conserve their shapes (time dependence). At the outer surface of the cone, we have synchronous circular radiators. Their radiation field forms a conical wave. Ultrashort terahertz pulses with gigawatt-level peak power can be generated with this device.

Atoms Absorb Low Frequency Electromagnetic Energy

This paper presents a method to measure TEM (transverse electromagnetic) waves absorbed by atoms. The results show the existence of a singularity in the universe which generates a broad spectrum of synchronized and extremely low frequency TEM waves in the period range 30 - 160 s. Atoms create resonance and absorb these TEM waves. The absorbed energy consists of a set of TEM waves where the sum generates an intrinsic static electric and magnet field. It is proposed that this static electric and magnetic field induces static forces within the atomic nucleus. The study describes a method to measure TEM waves absorbed by atoms (direction, frequency and amplitude). The study displays that chemical elements absorb TEM waves of different periods, supporting the hypothesis that TEM waves are absorbed by an atomic intrinsic resonance mechanism. The study displays a non-invasive method facilitating novel analyses of the atomic nucleus.

Gravity Caused by TEM Waves Operating on Dipoles in Atoms

The study displays the existence of a gravitational singularity in the universe generating synchronized and extremely low frequency plane TEM (transverse electromagnetic) waves. It is proposed that atomic intrinsic electromagnetic fields create resonance with these plane TEM waves, causing atoms to receive and to re-emit synchronized plane TEM waves. The energy flow of synchronized plane TEM waves, travelling in opposite directions between e.g. two atoms, creates mutual force of attraction, i.e. gravity. Consequently, gravity is not an intrinsic atomic feature; however, the result of passive atoms exposed to electromagnetic energy. The study describes how plane TEM waves emitted by the gravitational singularity were measured. The study also displays how gravity from the earth, moon, sun and the gravitational singularity was measured and how gravity was simulated using an electronic device. The present electromagnetic law of gravity is compared with Newtonian geometric law of gravity.

Simulation and experiment demonstration of an ultra-thin wide-angle planar metamaterial absorber

In this paper, we present the simulation and experimental validation of an ultra-thin planar metamaterial absorber, which is composed of Jerusalem crosses loaded by interdigital capacitors. By increasing the coupling capacitance between adjacent unit cells, we are able to significantly lower the operating frequency of the absorber. The measured results indicate that the metamaterial absorber achieves a peak absorption of 88.48% at 1.58 GHz. The total thickness and the unit cell size of the absorber are 2 mm and 11 mm, which are approximately 1/95 and 1/17 of the working wavelength, respectively. Additionally, the Jerusalem crosses and the metallic ground plane are connected by vias, this makes the metamaterial absorber achieve wide-angle absorption for both transverse electric and transverse magnetic polarizations electromagnetic wave. The absorptivity is still large even at the incident angle of 60o, and the frequency of the absorption peak almost has no deviation, this makes the absorber more practical.

Spin alignment induced by spin-orbit coupling in quantum plasmas

We develop a quantum hydrodynamic fluid model including spin-orbit coupling effects for electrons in quantum plasmas. An effective field being analogous to the magnetic field of the magnetic moment is found. In the strong-radiation case, this effective field has a more important influence on the motion of plasmas than the usual Bohm potential correction. We find a resonance-like mechanism by which the transverse electromagnetic (TEM) wave and the Langmuir wave both propagating in plasmas with the same frequency can cause a stationary alignment of spins. This alignment will become a traveling wave when the frequency increases. Then it will vanish when the reciprocal of the difference between the frequencies of TEM and Langmuir waves reaches a value shorter than the characteristic spin relaxation time.

PLASMA EFFECTS ON FAST PAIR BEAMS IN COSMIC VOIDS

The interaction of TeV gamma rays from distant blazars with the extragalactic background light produces relativistic electron-positron pair beams by the photon- photon annihilation process. The created pair beam distribution is unstable to linear two-stream instabilities of both electrostatic and electromagnetic nature in the unmagnetized intergalactic medium (IGM). The maximum electrostatic growth rate occurs at angles of 392 with respect to the pair beam direction, and is more than three orders of magnitude greater than the maximum Weibel growth rate, indicating that the linear oblique electrostatic instability operates much faster than the Weibel instability. The dissipation of the generated electrostatic turbulence is different for intense and weak gamma-ray blazars. For intense blazars, the normalized number of generated pairs n 22 = nb /[10–22 cm–3] exceeds the critical density nc (T) = 4.8 × 10–3 T 4 for given normalized IGM temperature T 4 = T/[104 K] necessary for the onset of the modulation instability, so that all free kinetic pair energy is dissipated in heating the IGM in cosmic voids. For weak blazars, half of the initial energy density of the beam particles is transferred to the electrostatic and electromagnetic fluctuations on timescales smaller than the inverse Compton energy loss timescale of the pairs. In both cases, this prevents the development of a full electromagnetic pair cascade as in vacuum. For weak blazars, the superluminal electrostatic fluctuations are dissipated by the inverse Compton scattering into transverse electromagnetic waves by the relaxed relativistic pair particles to optical frequencies, implying the occurrence of optical electrostatic bremsstrahlung pair halos from weak blazars with spectral flux densities below 50 μJy.

On the New Design of a 4-Port TEM Waveguide with a Higher Cutoff Frequency and Wider Test Volume

A new miniaturized 4-port waveguide generating a transverse electromagnetic wave is proposed. The waveguide presents enhanced performance of higher field uniformity in extended test volume up to an increased test frequency limit compared to that of the conventional 2-port waveguide. The advantageous features of the proposed waveguide have been obtained through a new design scheme based on effective miniaturization maintaining good impedance matching. Consequently, we can provide a more accurate electromagnetic compatibility test method, covering larger devices operating in higher frequencies, which is a marked improvement upon the conventional approaches.

Nonlinear quantum theory of stimulated Cherenkov radiation of transverse electromagnetic waves from a low-density relativistic electron beam in a dielectric medium

A nonlinear quantum theory of stimulated Cherenkov radiation of transverse electromagnetic waves from a low-density relativistic electron beam in an isotropic dielectric medium is presented. A quantum model based on the Klein-Gordon equation is used. The growth rates of beam instabilities caused by the effect of stimulated Cherenkov radiation have been determined in the linear approximation. Mechanisms of the nonlinear saturation of relativistic quantum Cherenkov beam instabilities have been analyzed and the corresponding analytical solutions have been obtained.

A Coaxial TEM Cell for Direct Measurement of UHF Artificial Magnetic Conductors [AMTA Corner

We have demonstrated a coaxial TEM (transverse electromagnetic wave) cell for direct measurement of artificial magnetic conductors (AMCs) in the VHF-UHF range. The advantages of the coaxial TEM cell are 1) it is a compact, bench-top device; and 2) it provides rapid, direct measurement of artificial-magnetic-conductor reflection response over a broad frequency range. We present measurements of various artificial-magnetic-conductor structures measured in the coaxial TEM cell, including 1) fixed-response, capacitor-loaded artificial magnetic conductors; 2) tunable varactor-loaded artificial magnetic conductors; and 3) wideband, tunable artificial magnetic conductors loaded with non-Foster, negative-inductance circuits. The measurements of the various artificial magnetic conductors were consistent with simulations. The coaxial TEM cell detailed here was 50 cm long with a 10.4 in diameter at the DUT, tapering to an N connector at the feed port. It was single-moded below 500 MHz. The design can be scaled to extend to other frequencies and other artificial-magnetic-conductor geometries.

A new light on the nature of light

The Quantum Theory and Special Relativity stand apart because their authors were admittedly unclear about Wave-quantum Unity of light and light propagating medium. A single experiment shows wave-quantum unity for low intensity light and moving electrons. In our Unified Theory light is propagated as a Wave-Quantum UNITY along transverse electromagnetic wave as per Poyinting vector in the physical 'sharmon medium' contiguously via 1-spin sharmons, which do not physically move. It appears as Quantum Theory's wave-or-quantum DUALITY for observing only one of the two not both characters at a time. Sharmon comprises a positive positrino and negative negatrino, the two all-composing indivisible elements of diameter 1.6x1033cm, electric charge 1.3729x10-30 esu, mass 2.596116x10-48 gm, spin = 1/2. These compose all forms of mass, energy, energy quanta like photon and particles like quarks, leptons and hadrons. Copenhagen interpretation of Quantum Theory is reviewed. Uncertainty Principle is rejected and replaced with new ‘Principle of Null Action’ based on the conservation of massenergy, momentum and action. Since spin of light-emitter does not fall and of absorber does not rise by one, NOT the 1-spin photon but 0-spin sharmon composed energy-quantum is emitted, absorbed and propagated. 'Contraction of space' and 'dilatation of time' are unrealistic. Constancy and invariance of light velocity c are explained, as also the observed variability, superluminality and subluminality which invalidate Relativity theories. Energized 1-spin sharmon replaces conventional photon and explains photoelectric effect and bending of light under gravity. Michelson-Morley got zero fringe-shift as light velocity in the sharmon medium entrained with earth is the same for the two perpendicular interfering beams. Non-Doppler cosmological redshift supports non-expanding universe.

Ultra-thin Polarization Independent Absorber Using Hexagonal Interdigital Metamaterial

An ultra-thin hexagonal microwave metamaterial absorber is described. It can absorb any polarized transverse electromagnetic wave because of its hexagonal shape. In spite of its very thin structure, almost 0.028λg, the absorber achieved 99% absorptivity at 11.35 GHz in experimental results because of the increased coupling losses, showing good agreement with simulation results. In addition, this high absorbance is unchanged for any polarized waves with the same frequency.

SUPERLUMINAL WAVES IN PULSAR WINDS

The energy lost by a rotation-powered pulsar is carried by a relativistic flow containing a mixture of electromagnetic fields and particles. In the inner regions, this is thought to be a magnetically dominated, cold, electron-positron wind that is well described by the MHD equations. However, beyond a critical radius r_{cr}, the same particle, energy and momentum fluxes can be transported by a strong, transverse electromagnetic wave with superluminal phase speed. We analyze the nonlinear dispersion relation of these waves for linear and circular polarization, and find the dependence of r_{cr} on the mass-loading, magnetization and luminosity of the flow, as well as on the net magnetic flux. We show that, for most isolated pulsars, the wind lies well outside r_{cr}, and speculate that superluminal modes play an important role in the dissipation of electromagnetic energy into nonthermal particles at the termination shock.

The dispersion relation and excitation of transverse magnetic mode electromagnetic waves in rippled-wall waveguide with a plasma rod and an annular dielectric

By using the linear field theory, the dispersion relation of electromagnetic waves in a rippled-wall waveguide with a plasma rod and an annular dielectric is obtained. In addition, by injecting a finite thick annular intense relativistic electron beam in this waveguide, the excitation of these waves is investigated. Furthermore, the effects of the radius of the plasma rod, the radius of the dielectric, the corrugation amplitude, and period on the frequency spectrum are investigated. Besides, the time growth rate of excitation of these waves by an annular relativistic electron beam is studied. Finally, to demonstrate the advantages of this rippled-wall waveguide, the dispersion relation and the growth rate of three simplified cases are investigated.

DOSIMETRY AND TEMPERATURE EVALUATIONS OF A 1800 MHz TEM CELL FOR IN VITRO EXPOSURE WITH STANDING WAVES

A 1800MHz transverse electromagnetic wave (TEM) cell is introduced for experiments investigating efiects on biological samples caused by the exposure from mobile communications. To characterize and quantify the exposure environment in the setup for standardized in vitro experiments, we evaluate the dosimetry and the exposure- induced temperature rise in cultured cells. The study is numerically based on the flnite-difierence time-domain (FDTD) formulation of the Maxwell equations and the flnite-difierence formulation of the bioheat transfer equation, with all algorithms and models strictly validated for accuracy. Two sample formations of cells are considered including the cell layer and the cell suspension cultured in the 35mm Petri dish. The TEM cell is designed to establish standing waves with the maximum E fleld and the maximum H fleld, respectively, at the position of the Petri dish. The Petri dish is oriented to E, iE, H, k, and ik directions of the incident fleld, respectively, to receive the exposure. The speciflc absorption rate (SAR) is calculated in cells for 10 exposure arrangements combined from the maximum flelds and Petri dish orientations. A comparison determines the best arrangement with the highest exposure e-ciency and the lowest exposure heterogeneity. The dosimetry and the exposure-induced temperature rise in cells are evaluated for the selected arrangement. To avoid thermal reactions caused by overheating, the maximum temperature rises in cells are recorded during the exposure. Based on the records, the temperature control is performed by setting limits to the exposure duration. We introduce a method to further reduce the exposure heterogeneity and evaluate the in∞uence of the Petri dish holder on the dosimetry and temperature rise. The study compares the TEM cell to the waveguide, as well as the standing wave exposure

Propagation properties of PD-induced electromagnetic wave in 66 kV GIS model tank with L branch structure

The authors investigated the effects of a corner that affects the transmission characteristics of a partial discharge (PD) induced electromagnetic (EM) wave, using a gas insulated switchgear (GIS) model with an L-shaped branch. The authors also experimentally investigated the change of amplitude of PD-induced EM wave around the passage of the Lshaped part using a disc-type ultra-high frequency (UHF) sensor located in a 66 kV model GIS. In addition, the effects of transverse electric (TE) mode were examined using a low pass filtering process, and a finite difference time domain (FD-TD) simulation with a simple model was performed. Subsequently, the effects of the L-shaped part that affected the EM wave transmission characteristic were discussed based on a comparison of the results with the analysis. It was found that the effects of the L-shaped part that affected the transmission characteristics of the PD-induced the EM wave did not affect the transverse electromagnetic (TEM) wave mode component, and reflection was generated with a higher frequency component above TE11 mode. It was also shown that the amplitude of the propagating EM wave changed significantly around the L-shaped part due to the superimposition of the reflected TE mode on the latter part of the incoming EM wave.

Phase evolution and electron bunching in two frequency undulator

Abstract A two frequency undulator is considered as a medium for interaction between an electron beam and two transversal electromagnetic waves. A one dimensional approach in small signal gain regime is employed and a set of linear equations governing the energy and phase evolution of the system is derived and is studied numerically. The bunching factor for two sort of bunching process, corresponding to two independent components of the undulator, is investigated.

Optical Nonlinearity of Subwavelength Metal-dielectric Gratings: Effects of Strong Anisotropy

The optical nonlinear properties of an effective anisotropic slab made of metal-dielectric lamellar gratings with a small grating-period-to-wavelength ratio Λ/λ → 0 is studied. It is shown that when a transverse magnetic electromagnetic wave obliquely illuminates such a slab, whose effective normal permittivity is much smaller than its tangential one, the normal wave vector inside the effective medium is extremely sensitive to the fluctuation of the tangential effective permittivity. Based on this characteristic, obvious nonlinear modifications of the phase delay and step-like transmission are obtained by a moderate input intensity even if the thickness of the slab structure is only less than λ/6.

Reflectionless passage of an electromagnetic wave through an inhomogeneous plasma layer

An exactly solvable model is used as a basis to study the reflectionless passage of a transverse electromagnetic wave through an inhomogeneous plasma containing large-amplitude, small-scale (subwave-length) structures (in particular, opaque regions) that cannot be correctly described by approximate methods. It is shown that, during the reflectionless passage of an electromagnetic wave, strong wave field splashes can occur in certain plasma sublayers. The nonuniform spatial plasma density profile is characterized by a number of free parameters describing the modulation depth of the dielectric function, the characteristic sizes of the structures and their number, the thickness of the inhomogeneous plasma region, and so on. Such plasma density structures are shown to be very diverse when, e.g., a wave that is incident from vacuum propagates without reflection through a plasma layer (wave barrier transillumination). With the cubic nonlinearity taken into account, a one-dimensional problem of the nonlinear transillumination of an inhomogeneous plasma can be solved exactly.

Aerial electromagnetic sounding of the lithosphere of Venus

Electromagnetic (EM) investigation depths are larger on Venus than Earth due to the dearth of water in rocks, in spite of higher temperatures. Whistlers detected by Venus Express proved that lightning is present, so the Schumann resonances ∼10–40 Hz may provide a global source of electromagnetic energy that penetrates ∼10–100 km. Electrical conductivity will be sensitive at these depths to temperature structure and hence thermal lithospheric thickness. Using 1D analytic and 2D numerical models, we demonstrate that the Schumann resonances—transverse EM waves in the ground-ionosphere waveguide—remain sensitive at all altitudes to the properties of the boundaries. This is in marked contrast to other EM methods in which sensitivity to the ground falls off sharply with altitude. We develop a 1D analytical model for aerial EM sounding that treats the electrical properties of the subsurface (thermal gradient, water content, and presence of conductive crust) and ionosphere, and the effects of both random errors and biases that can influence the measurements. We initially consider specified 1D lithospheric thicknesses 100–500 km, but we turn to 2D convection models with Newtonian temperature-dependent viscosity to provide representative vertical and lateral temperature variations. We invert for the conductivity-depth structure and then temperature gradient. For a dry Venus, we find that the error on temperature gradient obtained from any single local measurement is ∼100%—perhaps enough to distinguish “thick” vs. “thin” lithospheres. When averaging over thousands of kilometers, however, the standard deviation of the recovered thermal gradient is within the natural variability of the convection models, <25%. A “wet” interior (hundreds of ppm H 2O) limits EM sounding depths using the Schumann resonances to <20 km, and errors are too large to estimate lithospheric properties. A 30-km conductive crust has little influence on the dry-interior models because the Schumann penetration depths are significantly larger. We conclude that EM sounding of the interior of Venus is feasible from a 55-km high balloon. Lithospheric thickness can be measured if the upper-mantle water content is low. If H 2O at hundreds of ppm is present, the deeper, temperature-sensitive structure is screened, but the “wet” nature of the upper mantle, as well as structure of the upper crust, is revealed.