Dense Magnetoplasma Research Articles

Tripolar vortex formation in dense quantum plasma with ion-temperature-gradients

We have derived system of nonlinear equations governing the dynamics of low-frequency electrostatic toroidal ion-temperature-gradient mode for dense quantum magnetoplasma. For some specific profiles of the equilibrium density, temperature, and ion velocity gradients, the nonlinear equations admit a stationary solution in the form of a tripolar vortex. These results are relevant to understand nonlinear structure formation in dense quantum plasmas in the presence of equilibrium ion-temperature and density gradients.

Shear driven electromagnetic drift-waves in a nonuniform dense magnetoplasma

Linear characteristic properties of high- and low-frequency (in comparison with the cyclotron frequency) electromagnetic drift-waves are studied in a nonuniform, dense magnetoplasma (composed of electrons and ions), in the presence of parallel (magnetic field-aligned) velocity shear, by using quantum magnetohydrodynamic model. By applying the drift-approximation (viz., |∂ t|≪ωci≪ωce) to the quantum momentum equations, together with the continuity equations and the Poisson equation, we derive the governing equations for electromagnetic drift-waves with the shear flow. These linear equations are then Fourier transformed to obtain the dispersion relation in both high-frequency and low-frequency regimes. The dispersion relations are then discussed under various limiting cases.

Drift wave turbulence in a dense semi-classical magnetoplasma

A semi-classical nonlinear collisional drift wave model for dense magnetized plasmas is developed and solved numerically. The effects of fluid electron density fluctuations associated with quantum statistical pressure and quantum Bohm force are included, and their influences on the collisional drift wave instability and the resulting fully developed nanoscale drift wave turbulence are discussed. It is found that the quantum effects increase the growth rate of the collisional drift wave instability, and introduce a finite de Broglie length screening on the drift wave turbulent density perturbations. The relevance to nanoscale turbulence in nonuniform dense magnetoplasmas is discussed.

Electrostatic drift-wave instability in a nonuniform quantum magnetoplasma with parallel velocity shear flows

The propagation of high and low frequency (in comparison with the cyclotron frequency) electrostatic drift-waves is investigated in a nonuniform, dense magnetoplasma (composed of electrons and ions), in the presence of parallel shear flow, by employing the quantum magnetohydrodynamic (QMHD) model. Using QMHD model, a new set of equations is presented in order to investigate linear properties of electrostatic drift-waves with sheared plasma flows for dense plasmas. In this regard, dispersion relations for coupled electron-thermal and drift-ion acoustic modes are derived and several interesting limiting cases are discussed. For instance, it is found that sheared ion flow parallel to the external magnetic field can drive the quantum drift-ion acoustic wave unstable, etc. The present investigation may have relevance in dense astrophysical environments where quantum effects are significant.

New exact solitary wave and multiple soliton solutions of quantum Zakharov–Kuznetsov equation

By employing auxiliary equation method and Hirota bilinear method, the quantum Zakharov–Kuznetsov equation which arises in quantum magnetoplasma is investigated. With the aid of symbolic computation, both solitary wave solutions and multiple-soliton solutions are obtained. These new exact solutions will extend previous results and help us explain the properties of multidimensional nonlinear ion-acoustic waves in dense magnetoplasma.

Formation of dipolar vortices and vortex streets due to nonlinearly interacting ion-temperature-gradient-driven modes in dense magnetoplasmas

AbstractNonlinear equations which govern the dynamics of low-frequency (ω ⪡ ωci, where ω is the perturbation frequency of the wave and ωci is the ion gyro-frequency), ion-temperature-gradient-driven modes in the presence of equilibrium density, temperature and magnetic field gradients are derived. New set of nonlinear equations are derived. In the nonlinear case, new types of solutions in the form of dipolar vortices and vortex streets are found to exist in dense quantum plasma. These structures are found to be formed on very short spatial scales.

Erratum: “Nonlinear electromagnetic wave equations for superdense magnetized plasmas” [Phys. Plasmas 16, 072114 (2009)

By using the quantum hydrodynamic and Maxwell equations, we derive nonlinear electron-magnetohydrodynamic (MHD), Hall-MHD, and dust Hall-MHD equations for dense quantum magnetoplasmas. The nonlinear equations include the electromagnetic, the electron pressure gradient, as well as the quantum electron tunneling and electron spin forces. They are useful for investigating a number of wave phenomena including linear and nonlinear electromagnetic waves, as well as three-dimensional electromagnetic wave turbulence spectra arising from the mode coupling processes in dense magnetoplasmas.

Solitary waves and double layers in dense magnetoplasma

Using Sagdeev’s pseudopotential technique, ion acoustic solitary waves and double layers are studied subject to an external magnetic field in a two-component dense magnetoplasma consisting of ions and degenerate electrons. The ions are described by the hydrodynamic equations, and the electrons are assumed to follow the Thomas–Fermi density distribution. The pseudopotential is derived directly from Poisson’s equation without assuming the quasineutrality condition. The ranges of parameters for which solitary waves and double layers exist are studied in detail using Sagdeev’s technique.

Nonlinear electromagnetic wave equations for superdense magnetized plasmas

By using the quantum hydrodynamic and Maxwell equations, we derive the generalized nonlinear electron magnetohydrodynamic, the generalized nonlinear Hall-MHD (HMHD), and the generalized nonlinear dust HMHD equations in a self-gravitating dense magnetoplasma. Our nonlinear equations include the self-gravitating, the electromagnetic, the quantum statistical electron pressure, as well as the quantum electron tunneling and electron spin forces. They are useful for investigating a number of wave phenomena including linear and nonlinear electromagnetic waves, as well as three-dimensional electromagnetic wave turbulence spectra and structures arising from mode coupling processes at nanoscales in dense quantum magnetoplasmas.

Rayleigh–Taylor/gravitational instability in dense magnetoplasmas

The Rayleigh–Taylor instability is investigated in a nonuniform dense quantum magnetoplasma. For this purpose, a quantum hydrodynamical model is used for the electrons whereas the ions are assumed to be cold and classical. The dispersion relation for the Rayleigh–Taylor instability becomes modified with the quantum corrections associated with the Fermi pressure law and the quantum Bohm potential force. Numerically, it is found that the quantum speed and density gradient significantly modify the growth rate of RT instability. In a dense quantum magnetoplasma case, the linear growth rate of RT instability becomes significantly higher than its classical value and the modes are found to be highly localized. The present investigation should be useful in the studies of dense astrophysical magnetoplasmas as well as in laser-produced plasmas.

Surface waves in magnetized quantum electron-positron plasmas

AbstractThe dispersion properties of electrostatic surface waves propagating along the interface between a quantum magnetoplasma composed of electrons and positrons, and vacuum are studied by using a quantum magnetohydrodynamic plasma model. The general dispersion relation for arbitrary orientation of the magnetic field and the propagation vector is derived and analyzed in some special cases of interest (viz. when the magnetic field is directed parallel and perpendicular to the boundary surface). It is found that the quantum effects facilitate the propagation of electrostatic surface modes in a dense magnetoplasma. The effect of the external magnetic field is found to increase the frequency of the quantum surface wave. The existence of a singular wave on the boundary surface is also proved, and its properties are analyzed numerically. It is shown that the new wave characteristics appear due to the Rayleigh type of the wave.

Linear coupling of Alfven waves and acoustic-type modes in dense quantum magnetoplasmas

A coupled dispersion relation of low frequency shear Alfven waves and electrostatic waves in a dense quantum magnetoplasma is derived by using hydrodynamic model. The dispersive contribution of electron quantum effects is discussed for dynamic as well as static ions. The dominant role of electron Fermi pressure is highlighted and its comparison with the quantum pressure arising due to quantum Bohm potential is presented. For illustrative purpose, the results are analyzed numerically. The relevance of present work with the dense astrophysical and laboratory plasmas is pointed out with possible consequences.

Dispersion relations for electromagnetic waves in a dense magnetized plasma

AbstractDispersion relations for elliptically polarized extraordinary as well as linearly polarized ordinary electromagnetic waves propagating across an external magnetic field in a dense magnetoplasma are derived, taking into account the combined effects of the quantum electrodynamical (QED) field, as well as the quantum forces associated with the Bohm potential and the magnetization energy of the electrons due to the electron-1/2 spin effect. The QED (vacuum polarization) effects, which contribute to the nonlinear electron current density, modify the refractive index. Our results concern the propagation characteristics of perpendicularly propagating high-frequency electromagnetic waves in dense astrophysical objects (e.g. neutron stars and magnetars), as well as the next-generation intense laser–solid density plasma interaction experiments and quantum free-electron laser schemes.

Quantum Hall-MHD equations for a non-uniform dense magnetoplasma with electron temperature anisotropy

AbstractNonlinear quantum Hall-MHD equations for a warm dense magnetoplasma with an anisotropic electron pressure are derived. The nonlinear equations include the quantum force associated with electron tunneling effects. The newly found equations can be used to investigate the dense plasma stability, as well as different types of waves, instabilities, and nonlinear structures in a warm dense magnetoplasma.

Electrostatic drift vortices in quantum magnetoplasmas

A nonlinear equation similar to the Hasegawa–Mima equation for drift waves in dense quantum plasmas has been obtained. Therefore, electrostatic drift vortices can appear in nonuniform dense magnetoplasmas. These nonlinear structures can be of dipolar form as well as street-type vortices. It is noticed that these structures are formed on very short spatial scales. Further, it is discussed that quantum drift waves can couple with quantum ion acoustic waves, like classical plasmas, if the ion parallel dynamics is also considered.

Explosive and solitary excitations in a very dense magnetoplasma

A two-component dense magnetoplasma consisting of ions and degenerate electrons is considered. The basic set of hydrodynamic and Poisson equations are reduced to the Zakharov–Kuznetsov (ZK) equation by using the reductive perturbation technique. The basic features of the electrostatic excitations are investigated by applying a new direct method to the ZK equation. It is found that the latter has new solutions, which admit the propagation of either solitary or explosive pulses. The relevance of the new direct method to other nonlinear partial differential equations is also discussed.

Parallel velocity shear driven electrostatic waves in a very dense nonuniform magnetoplasma

It is shown that the parallel (magnetic field-aligned) velocity shear can drive the low-frequency (in comparison with the ion gyrofrequency) electrostatic (LF-ES) waves in an ultracold super-dense nonuniform magnetoplasma. By using an electron density response arising from the balance between the electrostatic and quantum Bohm forces, as well as the ion density response deduced from the continuity and momentum equations, a wave equation for the LF-ES waves is derived. In the local approximation, a new dispersion relation is obtained by Fourier transforming the wave equation. The dispersion relation reveals an oscillatory instability of dispersive drift-like modes in super-dense quantum magnetoplasmas.

Fully nonlinear ion-sound waves in a dense Fermi magnetoplasma

The nonlinear propagation of ion-sound waves in a collisionless dense electron-ion magnetoplasma is investigated. The inertialess electrons are assumed to follow a non-Boltzmann distribution due to the pressure for the Fermi plasma and the ions are described by the hydrodynamic (HD) equations. An energy balance-like equation involving a new Sagdeev-type pseudo-potential is derived in the presence of the quantum statistical effects. Numerical calculations reveal that the profiles of the Sagdeev-like potential and the ion-sound density excitations are significantly affected by the wave direction cosine and the Mach number. The present studies might be helpful to understand the excitation of nonlinear ion-sound waves in dense plasmas such as those in superdense white dwarfs and neutron stars as well as in intense laser-solid density plasma experiments.

Electroweak interactions between intense neutrino beams and dense electron-positron magnetoplasmas

The electroweak coupling between intense neutrino beams and strongly degenerate relativistic dense electron-positron magnetoplasmas is considered. The intense neutrino bursts interact with the plasma due to the weak Fermi interaction force, and their dynamics is governed by a kinetic equation. Our objective here is to develop a kinetic equation for a degenerate neutrino gas and to use that equation to derive relativistic magnetohydrodynamic equations. The latter are useful for studying numerous collective processes when intense neutrino beams nonlinearly interact with degenerate, relativistic, dense electron-positron plasmas in strong magnetic fields. If the number densities of the plasma particles are of the order of 1033 cm-3, the pair plasma becomes ultra-relativistic, which strongly affects the potential energy of the weak Fermi interaction. The new system of equations allows several neutrino-driven streaming instabilities involving new types of relativistic Alfven-like waves. The relevance of our investigation to the early universe and supernova explosions is discussed.

Nonlinear coupling between intense neutrino fluxes and dense magnetoplasmas

The nonlinear coupling between intense neutrino fluxes and a dense magnetized plasma is considered. It is shown that the coupling is governed by a pair of equations consisting of a nonlinear Klein-Gordon equation for the neutrinos and an equation governing a variety of magnetized plasma waves that are driven by the neutrino energy density. The system of equations is then used to investigate parametric instabilities, envelope solitons, as well as wake field generation. The relevance of our investigation to supernova explosions in pointed out.