Vortices in strongly magnetized nonuniform electron-positron-ion plasmas

The nonlinear mode coupling equations for electrostatic and electromagnetic waves in strongly magnetized nonuniform electron-positron-ion plasmas are derived. It is found that a small fraction of stationary ions (or high-Z charged impurities) can be responsible for the formation of coherent vortices which are forbidden when the ions are absent. Such vortices might significantly affect the transport properties of electron-positron plasmas in external magnetic fields.     

Enhanced diffusion in strongly magnetized astrophysical plasmas

We demonstrate that the diffusion coefficient for low energy particles, tied to a magnetic field which random walks, may be considerably larger than previously estimated in a strongly magnetized system — like the solar wind or the Galaxy. This is of interest with respect to propagation and lifetime considerations of low energy cosmic rays in the solar wind and the Galaxy.     

Nonlinear propagation of electromagnetic waves in magnetized electron-positron plasmas

The nonlinear interaction of the external magnetic field-aligned circularly polarized electro-magnetic radiation with a cold electron-positron plasma is considered. A set of nonlinear equations is derived describing the coupling of the radiation with cold electrostatic oscillations. Modulational instabilities and wave localization are discussed.     

Self-modulation of pulsar radiation in strongly magnetized electron-positron plasmas

A nonlinear Schrödinger equation is obtained for linearly polarized electromagnetic waves propagating across the ambient magnetic field in an electron-positron plasma. The nonlinearities arising from wave intensity induced particle mass modulation, as well as harmonic generation are incorporated. Modulational instability and localization of pulsar radiation are investigated.     

Ion-acoustic double layers in magnetized positive-negative ion plasmas with nonthermal electrons

The nonlinear ion-acoustic double layers (IADLs) in a warm magnetoplasma with positive-negative ions and nonthermal electrons are investigated. For this purpose, the hydrodynamic equations for the positive-negative ions, nonthermal electron density distribution, and the Poisson equation are used to derive a modified Zakharov–Kuznetsov (MZK) equation, in the small amplitude regime. It is found that compressive and rarefactive IADLs strongly depend on the mass and density ratios of the negative-to-positive ions as well as the nonthermal electron parameter. Also, it is shown that there are one critical value for the density ratio of the negative-to-positive ions (ν), the ratio between unperturbed electron-to-positive ion density (μ), and the nonthermal electron parameter (β), which decide the existence of positive and negative IADLs. The present study is applied to examine the small amplitude nonlinear IADL excitations for the (H⁺, O₂^-)(\mathrm{H}^{+}, \mathrm{O}_{2}^{-}) and (H⁺,H⁻) plasmas, where they are found in the D- and F-regions of the Earth’s ionosphere. This investigation should be helpful in understanding the salient features of the nonlinear IADLs in either space or laboratory plasmas where two distinct groups of ions and non-Boltzmann distributed electrons are present.     

Electromagnetic ion waves in cold relativistic plasmas

The high-energy processes which occur in many astrophysical objects have motivated recent studies (e.g., Tsintsadze and Tsikarishvili, 1976; Ferrariet al., 1978; Sweeney and Stewart, 1978) of large amplitude wave propagation in plasmas. Such investigations are also of interest for laboratory experiments where strong laser radiation interacts with a high-density target. In the present paper we shall show that even rather small amplitude waves in the presence of an external magnetic field can induce particle velocities which are comparable to the velocity of light. In this ultrarelativistic limit we shall demonstrate that two completely new types of circularly polarized waves appear and that under certain conditions, modulational instabilities occur. Finally we look at the possibility to relate the amplitudes and wavelengths of such waves to pulsar data.     

On the evolution of interacting,magnetized, galactic plasmas

The advent of three-dimensional, electromagnetic, and fully relativistic particle simulations allows a detailed study of a magnetized, rotating plasma, galaxy model. When two such models are simulated, an interaction yielding results resembling observational data from double radio sources, including the emission of synchrotron radiation, are obtained. Simulation derived morphologies, radiation intensities, frequency spectra, and isophote patterns are directly compared to observations. The constituent plasma parameters associated with the source Cygnus A are found to ben _e =1.8×10^?3 cm^?3,T=2.8 keV,B=20–30 gamma, with a small population of electrons accelerated to GeV energies by a rotation induced electric field. The results of these simulations, involving a computational resource of five CDC 7600 and five Cray-1 computers, strongly supports an inhomogeneous version of the Klein world model.     

The emission and absorption of waves by charged particles in magnetized plasmas

A semiclassical theory describing the emission and absorption of waves is applied to the interaction of charged particles with waves in magnetized plasmas. Spontaneous emission of all cold plasma wave modes is calculated in detail. The method gives the absorption coefficient for the waves and a diffusion equation in momentum space for the particles describing the effects of the induced processes.Coefficients describing the systematic change of particle parameters follow from the diffusion equation. Applications of astrophysical interest are outlined.     

Stokes parameters for thomson scattering in a cold magnetized plasma

The effect of a strong magnetic field on neutron stars or white dwarfs is calculated for Thomson scattering in a fully ionized collisionless plasma. The Stokes parameters for the scattered radiation are computed explicitly in terms of the state of polarization of the incident wave, the electron-cyclotron frequency, the plasma frequency, the angle of incidence, and the angle of scattering. The effects of the plasma are very insensitive to specific values of ( = ₂ ^p /²,_p denotes the electron plasma frequency) so long as 1, whereas the criterion for the magnetic field to substantially affect the Stokes parameters is that the photon frequency be less than the electron-cyclotron frequency. The effects of classical radiation damping and natural line broadening are briefly mentioned.     

Head on collision of dust ion acoustic solitary waves in magnetized quantum dusty plasmas

The Head on collision of dust ion acoustic solitary waves (DIASWs) in a magnetized quantum dusty plasma is investigated. Two sides Korteweg-de Vries (KdV) equations are obtained, the analytical phase shifts and the trajectories after the head-on collision of two DIASWs in a three species quantum dusty plasma are derive by using the extended version of Poincaré-Lighthill-Kuo (PLK) method. It is observed that the phase shifts are significantly affected by the quantum parameters like quantum diffraction, the ion cyclotron frequency and the ratio of the densities of electrons to ions.     

Head-on collision of ion-acoustic solitary waves in magnetized plasmas with nonextensive electrons and positrons

This article presents the first study of the head-on collision of two ion-acoustic solitary waves (IASWs) in magnetized plasmas with nonextensive electrons and positrons using the extended Poincaré-Lighthill-Kuo (PLK) method. The effects of the ion gyro-frequency to ion plasma frequency ratio, the positron to ion number density ratio, the electrons temperature to positrons temperature ratio, and the nonextensive parameter q on the phase shifts are investigated. It is shown that these factors significantly modify the phase shifts.     

Oblique collision effects on nonlinear quantum dust-acoustic solitary waves in magnetized dense dusty plasmas

The oblique collision of nonlinear quantum dust-acoustic (NQDA) solitary waves in a three-dimensional (3D) magnetized dense dusty plasma is investigated. Furthermore, two coupled Kortwege–de Vries equations for describing our model and the analytical phase shifts after the oblique collision of two NQDA solitary waves are derived using the extended Poincaré–Lighthill–Kuo (PLK) method. The modification in the phase shift and the trajectory of the NQDA solitary waves structures due to the inclusion of oblique collision and external magnetic field are discussed numerically. The numerical results are applied to high density astrophysical situations such as in superdense white dwarfs.     

Universal characteristics of ion-acoustic wave dynamics in magnetized plasmas with emphasis on Tsallis distribution

Using the extended Poincaré-Lighthill-Kuo (PLK) reductive perturbation method, which incorporates the phase-shift variations, it is shown that common features on propagation and head-on collisions of ion-acoustic waves exist for a magnetized plasmas of different inertial-less particle distributions. For instance it is remarked that, the soliton amplitude is always independent of magnetic field strength while strictly depends on its angle regarding the propagation direction. Both types of solitons (compressive or rarefactive) are shown to exist which are defined through the critical angle γ=π/2 or other critical values depending on plasma fractional parameters. These critical plasma parameter values also define the sign of head-on collision phase shift. Furthermore, it is proved that for a given set of plasma parameters there is always a relative angle of propagation regarding to that of the magnetic-field for which the soliton width is maximum. Current findings apply to a wide range of magnetized plasmas including those containing background dust ingredients or two-temperature inertial-less particles and may be used to study laboratory or astrophysical magnetoplasmas.     

Counterstreaming magnetized plasmas with kappa distributions – II. Perpendicular wave propagation

The analysis of the stability and the dispersion properties of a counterstreaming plasma system with kappa distributions are extended here with the investigation of perpendicular instabilities. Purely growing filamentation (Weibel-like) modes propagating perpendicular to the background magnetic field can be excited in streaming plasmas with or without an excess of parallel temperature. In this case, however, the effect of suprathermal tails of kappa populations is opposite to that obtained for parallel waves: the growth rates can be higher and the instability faster than for Maxwellian plasmas. The unstable wavenumbers also extend to a markedly larger broadband making this instability more likely to occur in space plasmas with anisotropic distributions of kappa-type. The filamentation instability of counterstreaming magnetized plasmas could provide a plausible mechanism for the origin of two-dimensional transverse magnetic fluctuations detected at different altitudes in the solar wind.     

The interaction of cosmic rays and magnetized plasma

A large flux of cosmic rays streaming through a magnetized plasma creates cavities of low plasma density and low magnetic field. The magnetic field focuses the cosmic ray trajectories into the cavities with the possible formation of filaments or beams of high-energy cosmic rays.     

Dust-acoustic solitary waves in a magnetized dusty plasmas with nonthermal ions and two-temperature nonextensive electrons

A rigorous theoretical investigation has been made on the obliquely propagating dust-acoustic (DA) waves in a magnetized dusty plasmas consisting of distinct temperature q-distributed electrons with distinct strength of nonextensivities, nonthermal ions and negatively charged mobile dust grains, and analyzed by deriving the Zakharov-Kuznetsov equation. It is found that the characteristics and the properties of the DA solitary waves (DASWs) are significantly modified by the external magnetic field, relative temperature ratio of ions, relative number densities of electrons as well as ions, the nonextensivity of electrons, nonthermality of ions and the obliqueness of the system. The possible implications of the results obtained from this analysis in space and laboratory dusty plasmas are briefly addressed.     

Quantum electron-acoustic solitary waves interaction in dense electron-ion plasmas

The effects of Bohm potential on the head-on collision between two quantum electron-acoustic solitary waves (QEASWs) in two electron species quantum plasma have been investigated using the extended Poincaré–Lighthill–Kuo (PLK) method. The analytical phase shifts after the head-on collision of the two QEASWs are derived. Numerically, in two cases (i.e., the dense solid state plasma and the dense astrophysical environments), the results show that the cold electron-to-hot electron number density ratio, the quantum corrections of diffraction and Fermi temperature of hot electrons have strong effects on the nature of the phase shifts and the trajectories of two QEASWs after collision.