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.

In a recent paper, Balescu (1980) criticizes the self-similar solution in the problem of anomalous plasma resistivity (Vekstein, Ryutov & Sagdeev 1970) and comes to the conclusion that this solution is not correct. The aim of this comment is to show why Balescu's arguments are erroneous.

We consider here the simplest case of the one-dimensional collisionless plasma in the presence of an external electric field.

I cannot agree with the reasoning of Vekstein, Ryutov & Sagdeev (1982) (VRS), the more so as I see no basic contradiction between their results and mine.

The basic equations of the quasi-linear theory are the kinetic equations determining the time evolution of the distribution functions of the electrons and ions, ∂tfe,i and of the spectral densities ∂tψσ(κ) (plus the definition of the diffusion coefficient and the dispersion relations). It is agreed that these equations must be satisfied in any event. The marginal stability is an added approximation (as VRS, of course, admit), and can only be accepted if it is compatible with the basic equations.

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.