Waves In Magnetoactive Plasma Research Articles

Dispersion Characteristics of Low-Frequency Electron Waves in a Magnetoactive Plasma of Arbitrary Density

The article studies waves in a collisionless magnetoactive plasma with frequencies much lower than the electron cyclotron frequency at an arbitrary ratio between the electron plasma and cyclotron frequencies. A general dispersion relation is obtained for the wave frequency as a function of the wave vector and the ratio of the plasma frequency to the cyclotron frequency. This relation is a bicubic equation with respect to frequency. Based on this equation, the existence domains of various wave modes depending on the specified parameter, their group velocity, polarization, and energy density are studied. Special attention is paid to low-frequency whistler waves in a low-density plasma, since, among the propagating wave modes existing in the specified range of parameters, whistler waves have the highest refractive index and play an important role in theresonant interaction of waves and particles.

One type of three-wave interaction of low-frequency waves in magnetoactive plasma of the solar atmosphere

We study the process of occurrence of “quasi-mode” decay instability of kinetic Alfven waves (KAW) in the chromosphere of a solar active region before a flare, namely, in plasma of magnetic loops near their footpoints. The decay of a primary KAW into a kinetic ion-acoustic wave and a secondary KAW was considered as a specific type of three-wave interaction. Necessary conditions for the KAW decay instability occurrence were found for two semiempirical models of the solar atmosphere with the use of a modified expression for the growth rate of instability in the case of nonlinear interaction of low-frequency waves with an abnormally low excitation threshold. It was shown that the main criteria for the development of this instability significantly depend on the amplitude of external magnetic field in the region under study as well as on a model of the solar atmosphere.

Radiation of whistler waves in magnetoactive plasma

In this paper the radiation of ring electric and magnetic currents in magnetoactive plasma in whistler frequency range is investigated. Particular attention is concentrated on the problem of variation of the radiated power distribution over the spectrum of excited waves with variation of the radiator parameters. Attention is also given to the radiation pattern structure near the resonance cone and peculiar caustic directions corresponding to the conic refraction and the Storey angle. It is shown that for ring electric current the consideration of the inhomogeneity in its distribution along the ring can be of importance and can lead, in particular, to a large increase of the relative contribution of the quasi‐electrostatic whistler mode waves to the total radiation power. Detailed numerical calculations have been carried out for the conditions close to ionospheric ones.

Damping of gravitational waves in a medium

An expression is obtained for the generalized susceptibility, relating the mean value of the energy-momentum operator tensor with perturbation metrics. In the special case of a gravitational plane wave it is shown that the wave damping decrement is determined by the anti-Hermitian part of the generalized susceptibility. The result obtained is used to investigate damping of gravitational waves in magnetoactive plasma.

Nonlinear Interaction of S‐Polarized Incident Radiation and Surface Waves in Magnetoactive Plasma

AbstractThe effect of an external magnetic field on the nonlinear interaction of S‐polarized electromagnetic radiation incident on a S‐polarized surface wave in a plasma layer was studied analytically. We have calculated the amplitudes of generated waves at combination frequencies. The generated waves are of P‐polarization and can be either electromagnetic or surface waves, depending on the signal of the value=\documentclass{article}\pagestyle{empty}\begin{document}$ ^{\chi '^2 = \frac{{k'^2 }}{{\varepsilon '}} - \frac{{\omega '^2 }}{{c^2 }} + k'\frac{\partial }{{\partial x}}\frac{{\varepsilon '_2 }}{{\varepsilon '\varepsilon '_1 }}} $\end{document}.

Excitation of waves in magnetoactive plasma by a strongly “spread” inhomogeneous electron beam

The stability of beam-plasma systems is studied assuming that the distribution of beam-electrons in the velocity space corresponds to the first period of the quasilinear relaxation. The necessary condition is derived for the usual quasilinear equations to be applicable within the whole period of quasilinear relaxation.

Interaction of inhomogeneous beam with surface waves in magnetoactive plasma

The present work investigates the excitation of potential surface oscillations on the plane boundary of the magnetoactive plasma by an inhomogeneous hot beam of charged particles. Expressions for the growth rates have been obtained.

On the Propagation Modes of Electromagnetic Waves in Magnetoactive Plasma

Magnetoactive Plasma内を伝播する電磁波のモードについて広い周波数帯に亘って考察する。電磁場のモードは, Ordinary Mode (正常波), Extraordinary Mode (異常波) の二種からなるが電子ガスの場合, X=1 (ω=ωp) において偏波面の磁気ベクトル回転方向は逆転し, これはそのまゝ電子・イオンブラズマに適用される。この偏波の模様と電磁波伝播の周波数特性とから電磁波伝播モードについて一つの解釈を示す。