Inhomogeneous Anisotropic Plasma Research Articles

Light propagation around a Kerr-like black hole immersed in an inhomogeneous anisotropic plasma in Rastall gravity: analytical solutions to the equations of motion

Light propagation around a Kerr-like black hole immersed in an inhomogeneous anisotropic plasma in Rastall gravity: analytical solutions to the equations of motion

Analytical study of light ray trajectories in Kerr spacetime in the presence of an inhomogeneous anisotropic plasma

We calculate the exact solutions to the equations of motion that govern the light ray trajectories as they travel in a Kerr black hole’s exterior that is considered to be filled with an inhomogeneous and anisotropic plasmic medium. This is approached by characterizing the plasma through conceiving a radial and an angular structure function, which are let to be constant. The description of the motion is carried out by using the Hamilton–Jacobi method, that allows defining two effective potentials, characterizing the evolution of the polar coordinates. The elliptic integrals of motion are then solved analytically, and the evolution of coordinates is expressed in terms of the Mino time. This way, the three-dimensional demonstrations of the light ray trajectories are given respectively.

Wave propagation in an inhomogeneous anisotropic plasma

A model is developed for small-amplitude waves propagating in a magnetically structured plasma with anisotropic pressures. Closure of the magnetohydrodynamic (MHD) equations is provided by a pair of polytropic laws, p⊥ρ−1B1−γ⊥= C⊥ and p∥ρ−γ∥Bγ∥−1 = C∥, such that for γ⊥=2, γ∥=3 the usual Chew–Goldberger–Low double-adiabatic expressions are recovered and for γ⊥=1, γ∥=1 double-isothermal conditions are obtained [L.-N. Hau and B. U. Ö. Sonnerup, Geophys. Res. Lett. 20, 1763 (1993)]. The wave equation represents the counterpart of that obtained for the isotropic plasma using the single energy equation, pρ−γ=C. Two applications are considered: the occurrence of surface waves on a magnetic interface and the field-line resonance.

Propagation of electromagnetic pulse with a Gaussian envelope through an inhomogeneous anisotropic plasma layer

Effects of an inhomogeneous anisotropic plasma layer on the propagation of a Gaussian envelope carrier pulse are studied numerically. It is found that the magnitude of the right‐handed circularly polarized component of the transmitted wave increases with increasing magnetostatic field in the direction of propagation. However, the magnitude of the left‐handed circularly polarized component of the transmitted wave first decreases with increasing magnetostatic field, up to a critical point, then increases with the increasing magnetostatic field; the critical point is dependent on the carrier frequency.

Eikonal expansion for an anisotropic plasma

The eikonal expansion developed by Weitzner and Batchelor is reformulated to study the cyclotron resonance in an inhomogeneous anisotropic plasma. It is shown that, to leading order, the functional dependences of the Poynting theorem, the cyclotron damping or growth [or the energy absorption (or emission)] rates on the unperturbed states are unaltered by anisotropy.

Parallel velocity shear instabilities in an inhomogeneous plasma

The stability of an inhomogeneous anisotropic plasma flowing along a straight magnetic field has been investigated. Both the flow velocity and the plasma density are spatially varying in a direction perpendicular to the magnetic field. The stability of an interface between an inhomogeneous anisotropic plasma flowing along the magnetic field and the non-conducting compressible gas of uniform density flowing parallel to the interface has also been discussed. The effect of gyroviscosity and inhomogeneity on the Kelvin-Helmholtz shear instability has been discussed in certain limiting situations.

Convective excitation of quasistatic waves in an inhomogeneous anisotropic plasma

Local as well as surface waves excited in a streamingless plasma are investigated. In addition to the gradient instabilities of an isothermal plasma now branches of a convective type are found in plasmas with a hot electron componentZ Te∥≫ Ti⊥. Both their frequencies and growth rates may exceed the ion cyclotron frequencyω, γ >ωBi even if the effect of the finite ion Larmor radius is negligible. Then the surface waves may become of enhanced importance. We compare, therefore, the conditions for excitation and the growth rates of the surface waves with those of the short wavelength (local) perturbations. Upper estimates of the saturated wave amplitudes are also given. For a special profile of the plasma density the problem is solved analytically also in the plasma boundary layer.

Lower hybrid heating in an inhomogeneous cylindrical plasma

The interaction of extraordinary waves with an inhomogeneous anisotropic plasma column at the lower hybrid frequency is investigated within the framework of the cold plasma theory. Numerical results for the wave absorption efficiency are presented for a wide range of plasma densities, magnetic field strengths, effective collision frequencies and column dimension values. Strong wave absorption occurs when the magnetic field strength approaches the value which corresponds to the ion cyclotron frequency. The plasma column exhibits a series of geometric resonances in the medium frequency range and a main absorption resonance in the h. f. range. The influence of temperature and nonlinear effects on the obtained absorption efficiency in the lower hybrid frequency range is discussed.

Asymptotic solution of oblique waves in inhomogeneous vertically magnetised plasma

A method for finding higher-order asymptotic solutions, as compared with the well known WKBJ approximation, is given for oblique electromagnetic waves in an inhomogeneous anisotropic plasma with a vertical magnetostatic field.