High-frequency surface waves in quantum plasmas with electrons relativistic degenerate and exchange-correlation effects

The propagation characteristics of high-frequency surface waves are studied in spin-1/2 quantum plasmas by considering the electron relativistic degenerate and exchange-correlation effects. Using the quantum fluid equations of magnetoplasmas in the presence of the quantum Bohm potential, spin magnetization energy, relativistic degenerate pressure, and exchange-correlation effects, a generalized dispersion relation is derived. The analytical and numerical results show that the relativistic degenerate and exchange-correlation effects significantly modify the propagation properties of high-frequency surface waves. It is found that under the influence of exchange-correlation effects, the frequency spectrum of high-frequency surface waves will be down-shifted. It is also indicated that the dispersion curve shifts up with the increase of relativistic gamma factor. Furthermore, the phase speed of the high-frequency surface waves increases with increasing electron number density. The current research is helpful to understand the propagation of the high-frequency surface waves in quantum plasmas, such as those in dense astrophysical environment.     

Electron exchange-correlation effects on dispersion properties of electrostatic waves in degenerate quantum plasmas

Based on the quantum Magnetohydrodynamic (QMHD) model, the obliquely propagation of electrostatic waves in degenerate magnetized quantum plasmas with electron exchange-correlation effects are theoretically investigated. The modified linear dispersion relations of electrostatic waves are obtained and discussed in some specific cases. The analytical results clearly show that the dispersion properties of the high frequency electron waves (including the Langmuir wave and upper-hybrid wave) and the low frequency ion acoustic wave are modified by the quantum effects together with the electron exchange-correlation effects. The numerical results depict that the Langmuir wave and upper-hybrid wave can be unstable in the presence of the electron exchange-correlation effects, and it is also evidently indicated that the electron exchange-correlation effects can reduce the phase velocity of the waves, especially in the high wave number region. The corresponding results should be of relevance for identifying electrostatic fluctuations which transport in an inhomogeneous and magnetized quantum plasmas.     

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.     

Two‐dimensional magnetosonic shock wave propagation in dense electron–positron–ion plasmas

Two‐dimensional (2D) magnetosonic wave propagation in magnetized quantum dissipative plasmas is studied. The plasma system is comprised of inertial ions, inertia‐less electrons, and positrons. The multi‐fluid quantum hydrodynamic model is used, in which quantum statistical and quantum tunnelling effects of electrons and positrons are included. Reductive perturbation analysis is performed to derive the Zabolotskaya–Khokhlov equation for the 2D propagation of a magnetosonic shock wave in a magnetized qauntum plasma. The effects of varying the different plasma parameters such as positron density and magnetic field intensity on the propagation characteristics of magnetosonic shock waves are discussed with non‐relativistic degenerate plasma parameters in astrophysical plasma situations.     

Obliquely propagating quantum solitary waves in quantum‐magnetized plasma with ultra‐relativistic degenerate electrons and positrons

The oblique propagation of the quantum electrostatic solitary waves in magnetized relativistic quantum plasma is investigated using the quantum hydrodynamic equations. The plasma consists of dynamic relativistic degenerate electrons and positrons and a weakly relativistic ion beam. The Zakharov‐Kuznetsov equation is derived using the standard reductive perturbation technique that admits an obliquely propagating soliton solution. It is found that two types of quantum acoustic modes, that is, a slow acoustic mode and fast acoustic mode, could be propagated in our plasma model. The parameter that determines the nature of soliton, that is, compressive or rarefactive soliton, for slow mode is investigated. Our numerical results show that for the slow mode, the determining parameter is ion beam velocity in the case of relativistic degenerate electrons. We also have examined the effects of plasma parameters (like the beam velocity, the density ratio of positron to electron, the relativistic factor, and the propagation angle) on the characteristics of solitary waves.     

Electrostatic Waves in Weakly Magnetized Quantum Plasmas

By using the quantum magnetohydrodynamic model, the electrostatic waves in weakly magnetized quantum plasmas are investigated. The electrons are treated as a quantum and magnetized species, while the ions are classical unmagnetized ones. The general dispersion relations are derived. It is shown that, both the high frequency electron waves （Langmuire wave and upper-hybrid wave） and the low frequency ion acoustic wave can propagate when the plasmas are cold.     

Electromagnetic properties of a chiral-plasma medium

The theoretical properties of a composite chiral-plasma medium are developed. By using the reaction theorem for a magnetized chiroplasma, we obtain the proof of nonreciprocity based upon the constitutive relationships between electromagnetic vectorsE, B, H, D. Using the Maxwell’s equations and the proposed constitutive relations for a chiral-plasma medium, we derive the vectorsE andH and from these equations, dispersion relations andE-field polarizations are based. The obtained results for waves propagating parallel to the external magnetic field in a cold magnetized chiro-plasma are compared with typical results obtained for a cold plasma. For circulary polarized waves, a new mode conversion is founded with the chiral effect. The chiral rotation is obtained and compared with the Faraday rotation. For waves propagating across the magnetic field, we found a shift of the cut-offs of ordinary and extraordinary waves. On the lower branch of the extraordinary wave mode there is no bands of forbidden frequencies and the reflection point vanishes when the chiral parameter increases.     

On the theory of Langmuir waves in a quantum plasma

Nonlinear quantum-mechanical equations are derived for Langmuir waves in an isotropic electron collisionless plasma. A general analysis of dispersion relations is carried out for complex spectra of Langmuir waves and van Kampen waves in a quantum plasma with an arbitrary electron momentum distribution. Quantum nonlinear collisionless Landau damping in Maxwellian and degenerate plasmas is studied. It is shown that collisionless damping of Langmuir waves (including zero sound) occurs in collisionless plasmas due to quantum correction in the Cherenkov absorption condition, which is a purely quantum effect. Solutions to the quantum dispersion equation are obtained for a degenerate plasma.     

Dielectric properties of a magnetized electron gas in a nanotube

A quantum expression is derived for the longitudinal permittivity of a magnetized electron gas in a quantum cylinder. The asymptotics of the dispersion law are calculated for longitudinal plasma waves in a degenerate electron gas. The approximations of the weak and strong spatial dispersions are considered. It is shown that the longitudinal permittivity is an oscillating function of the magnetic flux through the cross section of the nanotube.     

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.     

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.     

Spinor-electron wave guided modes in coupled quantum wells structures by solving the Dirac equation

A quantum analysis based on the Dirac equation of the propagation of spinor-electron waves in coupled quantum wells, or equivalently coupled electron waveguides, is presented. The complete optical wave equations for Spin-Up (SU) and Spin-Down (SD) spinor-electron waves in these electron guides couplers are derived from the Dirac equation. The relativistic amplitudes and dispersion equations of the spinor-electron wave-guided modes in a planar quantum coupler formed by two coupled quantum wells, or equivalently by two coupled slab electron waveguides, are exactly derived. The main outcomes related to the spinor modal structure, such as the breaking of the non-relativistic degenerate spin states, the appearance of phase shifts associated with the spin polarization and so on, are shown.     

Relativistic effects on the modulational instability of electron plasma waves in quantum plasma

Relativistic effects on the linear and nonlinear properties of electron plasma waves are investigated using the one-dimensional quantum hydrodynamic (QHD) model for a two-component electron?Cion dense quantum plasma. Using standard perturbation technique, a nonlinear Schr?dinger equation (NLSE) containing both relativistic and quantum effects has been derived. This equation has been used to discuss the modulational instability of the wave. Through numerical calculations it is shown that relativistic effects significantly change the linear dispersion character of the wave. Unlike quantum effects, relativistic effects are shown to reduce the instability growth rate of electron plasma waves.     

Neutrino-driven streaming instability of spin waves in dense magnetized plasma

The spin effects on electromagnetic waves in a strongly magnetized plasma with rare collisions are considered with the help of relativistic kinetic equations, which take into account the electron spin dynamics in self-consistent electric and magnetic fields. The growth rate of the electromagnetic spin waves in the presence of intense quasi-monoenergetic fluxes of neutrinos is determined.     

Planar and Nonplanar Shock Waves in a Degenerate Quantum Plasma

The nonlinear propagation of modified electron‐acoustic (mEA) shock waves in an unmagnetized, collisionless, relativistic, degenerate quantum plasma (containing non‐relativistic degenerate inertial cold electrons, both nonrelativistic and ultra‐relativistic degenerate hot electron and inertial positron fluids, and positively charged static ions) has been investigated theoretically. The well‐known Burgers type equation has been derived for both planar and nonplanar geometry by employing the reductive perturbation method. The shock wave solution has also been obtained and numerically analyzed. It has been observed that the mEA shock waves are significantly modified due to the effects of degenerate pressure and other plasma parameters arised in this investigation. The properties of planar Burgers shocks are quite different from those of nonplanar Burgers shocks. The basic features and the underlying physics of shock waves, which are relevant to some astrophysical compact objects (viz. non‐rotating white dwarfs, neutron stars, etc.), are briefly discussed. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The dispersive properties of a dielectric-rod loaded waveguide immersed in a magnetized annular plasma

Propagation properties of electromagnetic waves in a dielectric-rod waveguide immersed in a magnetized annular plasma are presented in this paper. The dispersion relations are derived and calculated. The results show that the dielectric-rod loading can make the structure less dispersive and the transmission frequency-band broadened.     

Electrodynamics and dispersion properties of a magnetoplasma containing elongated and rotating dust grains

The electrodynamics and dispersion properties of a magnetized dusty plasma containing elongated and rotating charged dust grains are examined. Starting from an appropriate Lagrangian for dust grains, a kinetic equation for the dust grain and the corresponding equations of motion are derived. Expressions for the dust charge and dust current densities are obtained with the finite size (the dipole moment) of elongated and rotating dust grains taken into account. These charge and current densities are combined with the Maxwell-Vlasov system of equations to derive dispersion relations for the electromagnetic and electrostatic waves in a dusty magnetoplasma. The dispersion relations are analyzed to demonstrate that the dust grain rotation introduces new classes of instabilities involving various low-frequency waves in a dusty magnetoplasma. Examples of various unstable low-frequency waves include the electron whistler, the dust whistler, dust cyclotron waves, AlfvÉn waves, electromagnetic ion-cyclotron waves, as well as lower-hybrid, electrostatic ion cyclotron, modified dust ion-acoustic waves, etc. Also found is a new type of unstable waves whose frequency is close to the dust grain rotation frequency. The present results should be useful in understanding the properties of low-frequency waves in cosmic and laboratory plasmas that are embedded in an external magnetic field and contain elongated and rotating charged dust grains.     

Dispersion Relations for Cold Plasmas Around Reissner-Nordström Black Holes

We investigate the general relativistic magnetohydrodynamic (GRMHD) equations for cold plasma around the Reissner-Nordström black hole. Applying 3+1 spacetime split we linearize the perturbed equations for non-magnetized/magnetized plasma in both rotating and non-rotating background. By Fourier analyze we then derive dispersion relations and investigate the existence of waves with positive angular frequency in the vicinity of the black hole horizon. The analysis finds propagation of negative phase and group velocities for rotating magnetized surroundings.     

Field theory of a traveling wave tube amplifier with a tape helix

A self-consistent relativistic field theory for a helix traveling wave tube (TWT) is presented for a configuration in which a magnetized pencil beam propagates through a tape helix enclosed with a loss-free well. A linear analysis of the interaction is solved subject to the boundary conditions imposed by the beam, helix, and wall. The wave equation for the fields within the electron beam corresponds to the Appleton-Hartree magnetoionic wave modes that are of mixed electrostatic/electromagnetic polarization. Hence, the determinantal dispersion equation that is obtained implicitly includes beam space-charge effects without recourse to a heuristic model of the space-charge field. This dispersion equation includes azimuthal variations and all spatial harmonics of the tape helix. Solutions that correspond to both the extraordinary (X) and ordinary (O ) solutions for the Appleton-Hartree modes are found numerically     

Electromagnetic Waves in Waveguide Partially Filled with Semiconductor Plasma

The dispersion of electromagnetic waves in waveguides partially filled with semiconductor plasma is investigated for unmagnetized and for strongly magnetized plasma. The effects which may be useful for the plasma electronics are found: In such waveguides there exist a large number of slow waves with typical frequencies ω ≈ ωP/√?_L. The filling at which the different modes at fixed phase velocity are maximum separated in wavelength is found. The thickness of the semiconductor layer at which this effect arises is about hundred micrometers and depends on the crystals' type. In addition to this, in strongly magnetized semiconductor plasma the maximum frequency separation of the typical plasma waves is found at fixed filling. Is it shown that in such systems there exist many surface waves which are of the slow wave type. In the case of strongly magnetized plasma coupling between nonsymmetrical EH- and HE- modes is shown to exist.