Dispersion Relation Of Surface Waves Research Articles

Rosensweig instability of ferrogel thin films or membranes

We derive the dispersion relation of surface waves for magnetic gel membranes or thin films at the interface between two fluids in the presence of an external magnetic field normal to the free surface. Above a critical field strength surface waves become linearly unstable with respect to a stationary pattern of surface protuberances. This linear stability criterion generalizes that of the Rosensweig instability for ferrofluid and ferrogel free surfaces to take into account bending elasticity and intrinsic elastic and magnetic surface properties of the film or membrane, additionally. The latter is of interest for uniaxial ferrogel film or membranes, which show a locked-in permanent magnetization.

Response of a ferrofluid to traveling-stripe forcing

We observe the dynamics of waves propagating on the surface of a ferrofluid under theinfluence of a spatially and temporally modulated field. In particular, we exciteplane waves by applying a traveling lamellar modulation of the magnetization. Bymeans of this external driving, both the wavelength and the propagation velocityof the waves can be controlled. The amplitude of the excited waves exhibits aresonance phenomenon similar to that of a forced harmonic oscillator. Its analysisreveals the dispersion relation of the free surface waves, from which the criticalmagnetic field for the onset of the Rosensweig instability can be extrapolated.

Surface waves between metallic films and truncated photonic crystals observed with reflectance spectroscopy

We have analyzed and demonstrated surface-wave excitations, by propagating waves in air, at the interface between a truncated photonic crystal (PC) and a silver film in the near-infrared. The truncated PC was fabricated with several unit cells of alternating SiO(2) and Si(3)N(4) layers. The dispersion relation of surface waves was calculated using the supercell method. A Fourier-transform infrared spectrometer measured the spectral reflectance of the fabricated sample at different incidence angles. An angle-resolved laser scatterometer measured the reflectance as a function of the incidence angle at the wavelength of 891 nm. The agreement between the resonance conditions obtained from experiments and the calculated dispersion relation manifests that surface waves at the PC-Ag interface may be utilized to build coherent thermal-emission sources.

Excitation of surface Josephson plasma waves in layered superconductors

This is a theoretical study of the resonant suppression of the specular reflection of terahertz waves in layered superconductors due to the excitation of surface Josephson plasma waves (SJPWs). Here, we consider in detail the specific case of SJPW excitations by evanescent electromagnetic waves via the attenuated total reflection of incident waves in a dielectric prism. We also derive the dispersion relation for surface waves propagating along the vacuum-superconductor interface parallel to the $\mathbf{a}\mathbf{b}$ plane. We show that, due to the SJPW excitation, the reflectivity of the incident wave depends resonantly on both its frequency and incident angle. We find the optimal conditions for the best matching of the incident wave and SJPWs, as well as for the total suppression of the specular reflection.

Dispersion relation for azimuthal electromagnetic surface waves on a magnetized annular plasma in a metal waveguide with coaxial anisotropic dielectric inner coating

AbstractThe dispersion relation of azimuthal electromagnetic surface waves on a magnetized annular plasma surrounded by a metallic cylindrical coaxial anisotropic dielectric lined waveguide is obtained. The thickness of the dielectric and its location in the waveguide are studied with respect to their effects on the number of spectra observed. The graphs of frequency spectra against the ratio of radii of the annular plasma and η = ωpe/Ωe are plotted. Finally, surface E-modes for coaxial anisotropic and isotropic dielectrics have been investigated.

Magnetohydrodynamic properties of incompressible Meissner fluids

We consider a superconducting material that exists in the liquid state, more precisely, in which the Meissner-Ochsenfeld effect persists in the liquid state. First, we investigate how the shape of such a hypothetical Meissner liquid will adapt to accomodate for an applied external field. In particular, we analyse the case of a droplet of Meissner fluid, and compute the elongation of the droplet and its quadrupole frequency as a function of the applied field. Next, the influence of an applied field on the flow of the liquid is studied for the case of a surface wave. We derive the dispersion relation for surface waves on an incompressible Meissner fluid. We discuss some candidate realizations of the Meissner fluids and for the case of a superconducting colloid discuss which regime of wave lengths would be most affected by the Meissner effect.

MAGNETOSTATIC SURFACE WAVES IN FERRITE-NONLINEAR NONMAGNETIC NEGATIVE PERMITTIVITY MATERIAL STRUCTURE

Magnetostatic surface waves have been investigated in a layered system of a nonlinear nonmagnetic negative permittivity material (NPM) and Ferrite (YIG). We derived the dispersion relation before numerically solving the dispersion relation of the TE nonlinear magnetostatic surface waves (NMSSW) in the proposed structure and the power flow. We found out that the wave effective nonlinear refractive index is much smaller in the forward direction than in the backward direction and consequently, the power flow is lower for the forward direction than the backward direction.

Modeling and simulation of the plasma absorption probe

The plasma absorption probe (PAP) was invented as an economical and robust diagnostic device to determine the electron density distribution in technical plasmas. It consists of a small antenna enclosed by a dielectric tube which is immersed in the plasma. A network analyzer feeds a rf signal to the antenna and displays the frequency dependence of the power absorption. From the absorption spectrum the value of the electron density is calculated. The original evaluation formula was based on the dispersion relation of plasma surface waves propagating along an infinite dielectric cylinder. In this letter the authors present the analysis of a less idealized configuration. The calculated spectra are in good qualitative agreement with their experimental counterparts, but differ considerably from those predicted by the surface wave ansatz. An evaluation scheme which takes our findings into account will improve the performance of the PAP technique further.

Numerical Simulation of Surface and Internal Waves using a Set of Nonlinear Equations with Vorticity

A functional for variational problems of multilayer-fluid systems with vorticity was presented, after which a set of nonlinear equations were derived to simulate surface and internal waves considering both strong nonlinearity and strong dispersivity of waves. The linear dispersion relations for surface and internal waves were shown also for deep-wave conditions. Stable results of surface waves propagating over a submerged breakwater, as well as internal waves reciprocating inside a closed tank, were obtained using the numerical model, where two-layer stratification was treated below a fixed horizontal plate. The internal waves resulted by the present model had a different period from that through a Boussinesq-type model. The surface waves over a slope steepened further due to the assumed vorticity effect.

Pair Annihilation Effects on Lower Hybrid Oscillation in Semi-Bounded Magnetized Dusty Pair Plasmas

The electron-positron pair annihilation effects on the electrostatic hybrid resonance oscillation are investigated in semi-bounded magnetized dusty pair plasmas. The surface wave dispersion relation is obtained by the plasma dielectric function with the specular reflection condition. The result shows the existence lower hybrid resonance oscillation modes in semi-bounded dusty pair plasmas. It is found that the electron-positron annihilation events enhance the lower hybrid resonance oscillation frequency. It is also found that the lower hybrid resonance frequency decreases with increasing the ratio of the positron density to the electron density. In addition, the lower hybrid resonance frequency decreases with increasing the strength of the magnetic field

Azimuthal electromagnetic surface waves in a rod dielectric magnetized plasma waveguide and their excitation by an annular relativistic rotating electron beam

The dispersion relation of azimuthal electromagnetic surface waves in a rod dielectric magnetized plasma waveguide is obtained. It is investigated that these waves in E-type can be excited by a thin annular relativistic rotating electron beam (TARREB). The effects of the rotating velocity of beam, radius TARREB, on the frequency spectra and growth-rate coefficient are presented.

Magnetostatic surface waves in a ferrite/dielectric/metal-strip-grating structure

The dispersion relation for magnetostatic surface waves in a ferrite/dielectric/metal-strip-grating structure is obtained. It is shown that dispersion of magnetostatic surface waves must be qualitatively the same as in a ferrite/dielectric/metal structure, while the slope of the dispersion curve in the region of backward magnetostatic waves existing in a ferrite/dielectric/grating structure (and in a ferrite/grating structure in particular) is considerably higher than the slope of this curve corresponding to a ferrite/dielectric/metal structure. It is found that this phenomenon can be explained by the dependence of the grating’s shielding capability on the wave number of magnetostatic surface waves. A grating shielding parameter is introduced and dependences of this parameter on the wave number that can be used to explain the phenomena observed in the experiment are determined.

Surface Waves and Rosensweig Instability in Isotropic Ferrogels

Summary We derive the dispersion relation of surface waves for isotropic magnetic gels in the presence of an external magnetic field normal to the free surface. Above a critical field strength surface waves become linearly unstable with respect to a stationary pattern of surface protuberances. This linear stability criterion generalizes that of the Rosensweig instability for ferrofluids by taking into account elasticity, additionally.

Electrostatic hybrid resonance modes in semi-bounded magnetized dusty plasmas

Electrostatic hybrid resonance oscillation modes are investigated in semi-bounded magnetized dusty plasmas. The surface wave dispersion relations are obtained for the orientation of the magnetic field using the specular reflection boundary condition with the plasma dielectric function. The result shows the existence of upper- and lower-hybrid resonance oscillation modes in semi-bounded magnetized dusty plasmas. It is found that the frequencies for the electrostatic upper- and lower-hybrid resonance oscillations are independent of the orientation of the applied magnetic field. In addition, the hybrid resonance frequencies are found to decrease as we increase the ratio of the electron plasma frequency to the electron cyclotron frequency.

Pair annihilation effects on dust ion acoustic surface wave in semi-bounded magnetized pair–ion–dust plasmas

The electron–positron pair annihilation effects on the dust ion acoustic surface wave are investigated in semi-bounded magnetized electron–positron–ion–dust plasmas. The dispersion relation of the low frequency dust ion acoustic surface wave is obtained by the plasma dielectric function with the specular reflection boundary condition. The results show that the frequency of the dust ion acoustic surface wave is found to be increased with increasing the annihilation of the electron–positron pair. In addition, the group velocity of the dust ion acoustic surface wave is also found to be increased with the annihilation of the electron–positron pair.

Comment on “Kinetic theory of surface waves in plasma jets” [Phys. Plasmas 9, 701 (2002)

It is shown that the dispersion relation of electromagnetic surface waves propagating on the interface between a vacuum and drifting Maxwellian plasmas derived in recent work [Phys. Plasmas 9, 701 (2002)] is incorrect. Correct electromagnetic and electrostatic dispersion relations are obtained.

Monochromatic surface waves on impermeable boundaries in two-component poroelastic media

The dispersion relation for surface waves on an impermeable boundary of a fully saturated poroelastic medium is investigated numerically over the whole range of applicable frequencies. To this aim a linear simplified model of a two-component poroelastic medium is used. Similarly to the classical Biot’s model, it is a continuum mechanical model but it is much simpler due to the lack of coupling of stresses. However, results for bulk waves following for these two models agree very well indeed which motivates the application of the simplified model in the analysis of surface waves. In the whole range of frequencies there exist two modes of surface waves corresponding to the classical Rayleigh and Stoneley waves. The numerical results for velocities and attenuations of these waves are shown for different values of the bulk permeability coefficient in different ranges of frequencies. In particular, we expose the low and high frequency limits, and demonstrate the existence of the Stoneley wave in the whole range of frequencies as well as the leaky character of the Rayleigh wave.

Surface waves in anisotropic Maxwellian plasmas

Dispersion relation of electromagnetic surface waves propagating on the interface between a vacuum and anisotropic Maxwellian plasmas is derived from Vlasov–Maxwell equations. By taking the limit of infinite speed of light in the electromagnetic dispersion relation, we derived dispersion relation of electrostatic surface waves, and we find that plasmas with equilibrium distribution f0α=(mα∕2πTα)exp{−[mα(vx2+vy2)]∕2Tα}δ(vz) (α=e,i; electrons and ions), where the z direction is normal to the interface, can be unstable to perturbations of ion-acoustic surface wave type.

Band gaps and the electromechanical coupling coefficient of a surface acoustic wave in a two-dimensional piezoelectric phononic crystal

In this paper we analyze the phononic band structure of bulk and surface waves in a two-dimensional periodic structure consisting of an array of piezoelectric cylinders in an isotropic background material. The explicit formulations of the bulk wave and the surface wave dispersion relations in such a structure are derived based on the plane wave expansion method. The band gaps and the electromechanical coupling coefficients for surface acoustic waves propagating in such a structure are calculated. The influences of material and geometrical anisotropy as well as the filling fraction on the electromechanical coupling coefficients are discussed, and some silent features are drawn. The results of this research may serve as an important reference for studying surface acoustic wave devices consisting of phononic structures.

Numerical Computation and Analysis on Radiation Field of the Plasma Column

There are many ways to excite the plasma, surface waves can be used to excite the plasma from a single end. One of them is by means of capacitively coupled low-pressure Radio-frequency (RF) discharge, plasma surfaces can be suspended in free space to serve as antenna elements. The surface wave driven plasma antenna produces sufficiently low noise so as to be useful for broadcast communications. When frequencies well below the plasma frequency, the plasma surface wave also propagates near the speed of Light just as on a metal-dielectric interface. According to opproach of radiation pattern of metal, the radiation patterns of travelling wave and standing wave transmitting in a column plasma in simple conditions are calculated. When relevant parameters like plasma density are changed, radiation pattern also changes correspondingly. Compared with metal, there are similar results. Using wave vector from dispersion relation of the plasma surface wave for an ideal column plasma, radiation pattern will change greaterly compared with radiation pattern in metal. Radiation pattern of plasma column can be controlled by changing plasma parameters, so utilizing plasma to transmitting the signal, there are certain reference meanings.