The properties of Alfvén solitons are examined (solitons propagating parallel to the magnetic field in a magnetized plasma) in the case when the plasma possesses a finite pressure. Starting from a two-fluid system of equations, the reductive perturbation method is used to derive a derivative nonlinear Schr ödinger equation, which is solved by a pseudo-potential method. An envelope soliton is found which possesses a width –amplitude relationship. The same functional form for the envelope of the magnetic energy density is obtained regardless of the value of the plasma &bgr;.

An approximate dispersion relation is obtained for quasi-longitudinal whistler mode propagation in the hot anisotropic plasma. The influence of plasma temperature and anisotropy on whistler energy focusing along the magnetic field and whistler trapping in the magnetospheric ducts are considered for the case when the whistler wave normal angle is not equal to zero.

We derive the dispersion formulae for electromagnetic waves including relativistic kinematics and a corresponding Maxwellian equilibrium distribution function without any approximations and having anisotropy in the streaming velocity. For non-relativistic temperatures, waves propagate when the streaming velocity is much smaller than the thermal velocity of the species, with varying thermal modes.

An expression is derived for the ponderomotive force acting in a cold collisionless magnetized plasma in a high-frequency electromagnetic field. Some related topics, such as the magnetic moment and solenoidal currents induced by the HF field are considered. A microscopic approach is used. The results are in complete agreement with the general expression for the ponderomotive force in a liquid medium with frequency dispersion obtained earlier by Washimi & Karpman by means of phenomenological considerations.

A theory of whistler wave propagation in axially symmetric density ducts is developed. Both density crests and troughs are considered. The duct width is assumed to be large compared with the parallel wave length. All considerations are based on the Maxwell equations. A number of effects that are not included in the ray theory and (or) the Schrödinger-type equations are elucidated. Among them is whistler detrapping from a density crest at ω < ½ωH. An analytical theory of the detrapping is developed and the corresponding wave attenuation rate in the duct is calculated.

We consider the stability against small perturbations of a class of exact wave solutions of the equations that describe an unmagnetized relativistic cold electron plasma. The main feature of these nonlinear waves is a transverse circularly polarized electric field with periodic amplitude modulation in the longitudinal direction. Floquet's theory of linear differential equations with periodic coefficients is used to solve the perturbation equations and obtain the instability growth rates.

We investigate nonlinear resonances and the averaged potential in a bounded non-isothermal plasma, placed in a constant magnetic field and a parallel external a.c. electric field. The treatment assumes one component MHD. It is assumed that a standing Alfvén wave exists before the electric field is switched on.

With respect to the propagation through a cold, unmagnetized, electron plasma of nonlinear, highly superluminous, plane waves of fixed profile, with electric vector in a fixed plane parallel to the direction of propagation, it is known that, in addition to the familiar longitudinal and quasi-transverse waves, there can also be a third periodic wave. The perturbation method by which this third wave has previously been analysed is of restricted validity, and fails to describe how the wave disappears in the approach to the small-amplitude limit, where the longitudinal and transverse waves alone survive.

The influence of a metallic wall on the velocity distribution of the neutral particles in a plasma has been experimentally determined by spectroscopic measurements of a Doppler broadened line. Typical characteristic facts of the plasma –wall interaction can be explained quantitatively by means of a one-dimensional kinetic equation, which is solved in the plasma –wall interaction region, assuming reasonable boundary conditions on the wall surface.

In this paper, we have discussed the possibility of excitation of zero-frequency modes by a finite-amplitude electron-sound wave in a highly non-isothermal (Ti ≫ Te) magnetoplasma. According to our investigation, the modulational instabilities of the electron-acoustic waves may produce enhanced twodimensional vortices (convection cells) and magnetic field fluctuation. Both of them can, in turn, modify transport properties of a hot magnetoplasma.

Our results could be applicable to plasmas in the earth's magnetotail (Frank, Ackerson & Lepping 1976) or thetapinches, both of which have Ti≫Te. However, for thetapinch application, one should actually modify our results to include plasma non-uniformities. In such a situation, instead of electron-acoustic waves, one encounters ion drift waves (e.g. Shukla, Yu & Varma 1981) whose modulational instabilities can readily be studied following the procedure discussed here.

Owing to the lack of experimental data, we cannot at present verify predictions of our theory for plasmas either in space or in a laboratory. However, a typical example shows that the growth rates of both the convection cells and the magnetostatic modes are quite substantial. Hence, the phenomena discussed here may indeed appear in nature.

We are grateful to Ming Yu for many useful discussions. The work of one of us(P. K. S.) was performed under the auspices of the Sonderforschungsbereich Plasmaphysik Bochum/J ülich. One of us (H.U.R.) thanks the Deutsche Akademische Austauschdienst for the award of a fellowship.

The scattering of an ordinary electromagnetic wave into a circularly polarized wave by electron-acoustic oscillations is considered.

In this paper, we consider a parametric instability involving electron-acoustic waves which does not have a counterpart in a hot electron plasma, namely the scattering of an ordinary electromagnetic wave into a circularly polarized wave by electron-acoustic waves.

The stability of steady flow of an N-component, warm or cold, cylindrical electrostatic plasma is considered. The plasma is immersed in a magnetic field B0(r), where r is the radial co-ordinate, which is allowed to have both axial and azimuthal components. The unperturbed quantities are allowed to be arbitrary functions of r consistent with the zero-order equations. A sufficient condition for the stability of a rotating flow to axisymmetric perturbations is obtained.

A uniformly-streaming, semi-infinite, incompressible, infinitely-conducting plasma subjected to a gravitational field is confined by a vacuum magnetic field aligned with the stream. The system is disturbed by introducing a source of external steady pressure acting on the interface between the plasma and the magnetic field. The resulting wave motion at the interface is studied by using the Fourier-transform method to determine the solution for the displacement of the interface.

The dispersion relation of a deuterium –hydrogen plasma is investigated near the ion cyclotron frequency of hydrogen at varying hydrogen temperatures. It is found that at low hydrogen-to-deuterium temperature ratios, only the fast mode and the ion Bernstein mode are coupled around the hybrid layer. Above a certain critical temperature ratio Th< Thc, these two modes become coupled also to a third mode. Around and above Thc, the wave equation is of sixth order rather than of the fourth order previously discussed.

The propagation of intermediate waves in a turbulent relativistic plasma, characterized by an effective electrical conductivity σeff due to microinstabilities, is studied. The process is governed by a set of diffusion-type equations. An initial magnetic perturbation of a Gaussian wave form subsequently decays owing to dissipation. For the almost-Newtonian gas and the ultra-relativistic gas, relativistic effects tend to change the polarization of the initial magnetic impulse from a linearly polarized wave to a circularly polarized wave.

Numerical evaluations of the dielectric response functions were performed and plasma dispersion relations computed for the full function where coupling due to finite β and k∥ are maintained. The basic plasma parameters were chosen to represent 2XIIB with variations in temperature. It is found that various branches exchange polarization and differ somewhat from the more ideal dispersion relation such as the shear Alfvén wave.

The electrostatic instability of bounded beam –plasma systems as well as its consequences on the ignition of the beam –plasma discharge (BPD) at low pressures and magnetic field strengths are investigated. For this purpose, configurations consisting of a finite radius electron-beam –plasma system whose edge is far away from a confining coaxial metallic container are considered; an ambient, partially ionized gas filling the container is also present.