Plasmon Mechanism of Overdense Plasma Heating

This paper attempts to introduce an effective mechanism of plasma heating of an overdense plasma layer. This mechanism is directly related to the phenomena of anomalous transparency of an overdense plasma layer. High temperature is achieved due to the resonant excitation of the coupled surface waves on both sides of the plasma layer. The dissipative energy of the collisional effects appears as an effective heating source in this mechanism. The solutions of the heat equation under the resonant situations are obtained in the steady and unsteady states conditions. The main factors, affecting the considered plasma heating mechanism, are also discussed. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Dust-Lower-Hybrid Surface Waves in Classical and Degenerate Plasmas

The dispersion relation for general dust low frequency electrostatic surface waves propagating on an interface between a magnetized dusty plasma region and a vacuum is derived by using specular reflection boundary conditions both in classical and quantum regimes. The frequency limit ω«ω_ci«ω_ce is considered and the dispersion relation for the Dust-Lower-Hybrid Surface Waves (DLHSW's) is derived for both classical and quantum plasma half-space and analyzed numerically. It is shown that the wave behavior changes as the quantum nature of the problem is considered.     

Surface waves on the relativistic quantum plasma half-space

We present a theoretical investigation on the propagation of surface waves on the relativistic quantum plasma half-space. The dispersion relations of surface plasmon polaritons (SPPs) and electrostatic surface waves containing relativistic quantum corrected terms are derived. Results show that the frequency of SPPs has a blue-shift, and surface Langmuir oscillations can propagate on the cold plasma half-space due to quantum effects. Numerical evaluation indicates that quantum effects to SPPs and electrostatic surface waves are significant and observable.     

Excitation of surface plasmons at the boundary of overdense plasma

The excitation of surface plasmons （SPs） with a strip grating at the boundary of an unmagnetized overdense plasma has been investigated theoretically and experimentally. An incident electromagnetic radiation was p-polarized at the frequency of 5 GHz. Experiments showed that when the plasma density was four times higher than the critical density with the grating present, and the SPs could be excited at the boundary of the overdense plasma. Contribution of the glass layer in the formation of the SP dispersion relation was examined. When the incident electromagnetic radiation was coupled into SPs the coupling order with the effective permittivity was simulated qualitatively. We find that the existence of SPs at the boundary of overdense plasma indicates that the reflection coefficient of the incident electromagnetic radiation reaches its minimum and even becomes total absorption. In this work the plasma density was diagnosed by a Langmuir double probe.     

Propagation of a TE surface mode in a relativistic electron beam-quantum plasma system

The dispersion properties of a transverse electric (TE) surface waves propagating along the interface between a magneto-quantum plasma-relativistic beam system and vacuum are studied by using the quantum hydrodynamic model. The general dispersion relations are derived and analyzed in some special cases of interest. Moreover, the effects of density gradients for the beam and plasma on the dispersion properties of surface waves are investigated. The kind of dispersion relations depends strongly on the ambient magnetic field Bo via the gyro-frequency ωc, the quantum parameters, and the width of the plasma layer as well as the relativistic factor for the electron beam. It is found that the quantum effects play a crucial role to facilitate the propagation of TE surface waves.     

Quantum and geometric effects on the symmetric and anti-symmetric modes of the surface plasma wave

The propagation of the surface quantum plasma waves is investigated in a thin quantum plasma slab. The symmetric and anti-symmetric dispersion modes of the quantum surface wave are obtained by the plasma dielectric function with the kinetic dispersion model for the slab geometry. The quantum mechanical and slab geometric effects on the symmetric and anti-symmetric modes are also discussed.     

Quantum photonic crystals—Quantytes

Optical properties and structural characteristics of quantum photonic crystals??quantytes??are investigated. Quantytes are crystalline structures with periodically arranged quantum dots of dielectrics, ferroelectrics, magnets, or metals. They feature so-called stop bands in which anomalous reflection of electromagnetic radiation from the photonic crystal surface is observed. It is found that quantytes are characterized by a negative refractive index and anomalous deceleration of electromagnetic waves in some spectral ranges. Possible uses of quantytes as devices for recording and reading of optical information, optical elements with negative refraction, selective mirrors, and narrow-band light filters are discussed.     

Streuung elektromagnetischer Oberflächen- und Volumenwellen an rauhen Oberflächen. Teil I. Allgemeine Grundlagen

Scattering of Electromagnetic Surface and Bulk Waves from Rough Surfaces. Part I. General Theory A classical theory of scattering of electromagnetic surface and bulk waves on rough surfaces (dielectrics or conductors) is given. The primary wave creates a surface polarization on the rough boundary presenting the source for the radiation of scattering. These roughness-caused polarization must be considered in the wave equations and in the boundary conditions of the fields, too. General expressions for the spectral power density of surface and bulk scattering waves will be given. The excitation of surface polarization can result from primary waves homogenously or inhomogenously.     

Electromagnetically induced transparency in high-temperature magnetoactive plasma

We investigate a classical analog of electromagnetically induced transparency (EIT) currently popular in quantum electronics. We consider EIT for electron cyclotron waves in finite-temperature plasma. We derive an expression for the effective refractive index of an electromagnetic wave and study the dispersion and absorption of this wave under EIT conditions. Allowance for thermal motion is shown to radically change the behavior of the dispersion curves for the signal wave in the EIT region compared to the case of cold plasma.     

Novel dispersion properties of one-dimensional photonic crystals containing a defect made of twin prisms

We design a one-dimensional photonic crystal containing a defect made of twin prisms and study its transmission properties using the transfer matrix method. The incident waves with different wavelengths can be transmitted out at different positions of the last interface of the structure, i.e., one wavelength corresponds to a single export point. Such a structure can be used as a novel dispersion separator. The resolution of this dispersion separator depends on the structure and indices of the twin prisms.     

Total absorption of an electromagnetic wave by an overdense plasma

We show both theoretically and experimentally that an electromagnetic wave can be totally absorbed by an overdense plasma when a subwavelength diffraction grating is placed in front of the plasma surface. The absorption is due to dissipation of surface plasma waves (plasmons polaritons) that have been resonantly excited by the evanescent component of the diffracted electromagnetic wave. The developed theoretical model allows one to determine the conditions for the total absorption.     

Extraordinary Electromagnetic Waves in Weakly Relativistic Degenerate Spin-1/2 Magnetized Quantum Plasmas

By using the relativistic quantum magnetohydrodynamic model, the extraordinary electromagnetic waves in magnetized quantum plasmas are investigated with the effects of particle dispersion associated with the quantum Bohm potential effects, the electron spin-1/2 effects, and the relativistic degenerate pressure effects. The electrons are treated as a quantum and magnetized species, while the ions are classical ones. The new general dispersion relations are derived and analyzed in some interesting special cases. Quantum effects are shown to affect the dispersion relations of the extraordinary electromagnetic waves. It is also shown that the relativistic degenerate pressure effects significantly modify the dispersive properties of the extraordinary electromagnetic waves. The present investigation should be useful for understanding the collective interactions in dense astrophysical bodies,such as the atmosphere of neutron stars and the interior of massive white dwarfs.     

Electrostatic Surface Waves on Semi-Bounded Quantum Electron-Hole Semiconductor Plasmas

The electrostatic surface waves on semi-bounded quantum electron-hole semiconductor plasmas are studied within the framework of the quantum hydrodynamic model, including the electrons and holes quantum recoil effects,quantum statistical pressures of the plasma species, as well as exchange and correlation effects. The dispersion characteristics of surface electrostatic oscillations are investigated by using the typical values of Ga As, Ga Sb and Ga N semiconductors. Numerical results show the existence of one low-frequency branch due to the mass difference between the electrons and holes in addition to one high-frequency branch due to charge-separation effects.     

量子等离子体中波的色散关系以及朗道阻尼

利用动理学理论研究量子等离子体中波的色散关系和电子朗道阻尼.从电子的量子流体动力学方程和动理学描述下的光子运动方程出发,研究量子效应对光子朗道阻尼的修正.研究发现量子效应只对纵波模式,即电子等离子体波的色散关系有修正,对横向电磁波的色散关系没有影响.量子效应减小了朗道阻尼,起着朗道增长的作用. 关键词： 量子等离子体 朗道阻尼 电子等离子体波 色散关系     

The Rayleigh-Taylor instability and internal waves in quantum plasmas

Influence of quantum effects on the internal waves and the Rayleigh-Taylor instability in plasma is investigated. It is shown that quantum pressure always stabilizes the RT instability. The problem is solved both in the limit of short-wavelength perturbations and exactly for density profiles with layers of exponential stratification. In the case of stable stratification, quantum pressure modifies the dispersion relation of the inertial waves. Because of the quantum effects, the internal waves may propagate in the transverse direction, which was impossible in the classical case. A specific form of pure quantum internal waves is obtained, which do not require any external gravitational field.     

The anomalous penetration of intense circularly polarized electromagnetic beam through overdense magnetized plasma

The steady state nonlinear propagation of an intense, circularly polarized electromagnetic beam in an inhomogeneous magnetized plasma has been investigated in paraxial approximation. The laser induces a large oscillatory velocity on electrons, raising their mass and lowering the plasma frequency. Further, rising due to cyclotron resonance effect. The propagation of the electromagnetic waves in magnetized plasma in both the extraordinary and ordinary mode is analyzed. The nonlinearity in dielectric function is considered in presence of external magnetic field due to saturation effects for arbitrary large intensity, which leads to focusing/defocusing of the beam. The focusing effect along with magnetic field helps in the process of anomalous penetration of the beam by enhancing the depletion of the plasma from the axial region. The penetration increases with the incident beam power up to some critical value beyond which it rises abruptly when all electrons have been driven out of the axis. The cyclotron resonance effect awfully supports the laser beam to propagate inside the overdense plasma region. Numerical computations are performed for typical parameters of relativistic laser–plasma interaction applicable for underdense and overdense plasma.     

Ultra-short pulse laser interaction with transparent dielectrics

The interaction of intense, ultra-short laser pulses (USLP) with a surface of transparent dielectrics is considered. The combination of multi-photon absorption and impact ionization generates a plasma layer at the dielectric boundary. Interaction with the plasma self-consistently determines the amount of reflected, transmitted and absorbed light, and the spatial distribution of electron density. In the present paper, we model the interaction of USLP with transparent dielectrics. We calculate the evolution of electron density profiles and the variation of reflection, transmission and absorption of laser radiation during the pulse. We show that the laser-created surface plasma acts as a filter transmitting only the leading edge of the laser pulse. The transmitted energy is approximately fixed, nearly independent of input pulse energy. The transmitted energy increases with pulse duration. This increased energy is manifested in the formation of cylindrical shock waves directly applicable to recent experiments investigating absorption and shock generation in water. PACS 79.20.Ds; 81.15.Fg; 05.45.Pg     

On the low-threshold parametric mechanism of the anomalous power absorption in electron cyclotron resonance heating experiments in toroidal devices

The experimental conditions that facilitate the excitation of parametric decay instabilities upon the electron cyclotron resonance heating of a plasma at the second harmonic extraordinary wave in tokamaks and stellarators and, as a result, make anomalous absorption of microwave power possible have been analyzed. It has been shown that, in the case of a nonmonotonic radial profile of the plasma density, when the beam of electron cyclotron waves passes near the equatorial plane of a toroidal device, the parametric excitation of electron Bernstein waves, as well as the generation of ion Bernstein waves propagating from the parametric decay region to the nearest ion cyclotron harmonic, where they efficiently interact with ions, is possible. The proposed theoretical model can explain the anomalous generation of accelerated ions observed upon electron cyclotron heating in small and moderate toroidal facilities.     

Corrections to the classical continuity boundary conditions at the interface of a composite medium

Using the multiple-scales homogenization method, we derive generalized sheet transition conditions (GSTCs) for electromagnetic fields at the interface between two media, one of which is free-space and the other a certain type of composite material. The parameters in these new boundary conditions are interpreted as effective electric and magnetic surface susceptibilities, which themselves are related to the geometry of the scatterers that constitute the composite. We show that the effective tangential E and H fields are not continuous across the interface except in the limit when the lattice constant (the spacing between the scatterers—atoms, molecules or inclusions in the case of a composite material) of the composite medium is very small compared to a wavelength. We derive first-order corrections to the classical continuity conditions. For naturally occurring materials whose lattice constants are on an atomic scale, these effects are shown to be negligible for waves at optical frequencies or lower. However, once the lattice constant becomes a significant fraction of a wavelength (which is the case for many artificial dielectrics and metamaterials), the corrections can be important. In previous work we have alluded to the fact that such a GSTC is needed to correctly account for the surface effects when extracting the effective material properties of a metamaterial. The results of this current paper justify the assumptions made in that previous work. In general, these GSTCs will result in corrections to the classical Fresnel reflection and transmission coefficients (which are themselves merely zeroth-order approximations to the actual reflection and transmission coefficients), and in a separate publication we will use these GSTCs to address this issue.