[en] The threshold and growth rate are calculated for a parametric instability occuring when a high frequency electron plasma wave is scattered off a low frequency diffusion mode in a magnetized collisional plasma. The uncoupled diffusion mode is a non-propagating electrostatic spatially periodic disturbance. The three wave mode coupling present in the process of scattering is assumed to take place through collisional heating (rather thatn through the pondermotive force), thus giving rise to low frequency temperature fluctuations at the beat frequency of two high frequency waves. In the analysis we retain both the Stokes and anti-Stokes couplings which are equally important when the ratio of the Debye length to the wave length of the incident wave. The manner in which the instability grows is shown to be in agreement with the Manley-Rowe principle. It is found that 1) the low frequency mode acquires a real (propagating) frequency owing to the joule heating coupling, and 2) the frequency of the scattered wave is higher than the incident wave frequency, in contrast to the usual parametric instabilities where the pump of higher frequency gives up energy to the excited wave of slightly lower frequency. In an alternative analysis in which we consider explicitly the direction of power glow between two high frequency waves, the results stated above, obtained from the dispersion relation, are confirmed. (author)

[en] The dispersion equation is studied of the low-frequency flute instability driven by the high-frequency electrostatic eigenmode excited in a plasma slab. If the amplitude of h.f. mode is small the equation is solved and the explicit formula for the maximum growth rate is obtained. As an example, the problem was investigated numerically for a slab with a parabolic density profile. In the model heating could only be considered in the frequency band stretching from the lower hybrid frequency to the electron cyclotron frequency. For this case it follows from the calculation that the danger of the low-frequency disruption of a plasma in the process of heating is serious. (author)

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[en] The linear stage of the two-stream instability of interpenetrating, collisionless plasmas which do not contain a magnetic field and which are sharply bounded by a longitudinal external magnetic field is studied. Both the kinetic and the hydrodynamic models of the instability are analyzed under the assumption of cold electrons. Conditions for the onset of the instability are given. Numerical calculations of the growth rates and a picture of the modes are reported. The instability is shown to be aperiodic and to have a long-wave limit (it also has a short-wave limit in the kinetic treatment). The growth rates are typically on the order of v/sub T//a, where v/sub T/ is the ion thermal velocity, and a is the transverse dimension of the plasmas

[en] The potential of small disturbance in an inhomogeneous beam-plasma system may be represented in the form of superposition of oscillations with continuous spectra of complex frequencies. The effects considered are due to the limitation of continuous spectra of oscillations. It is necessary to take into account the boundary points of spectra while determining the asymptotics for large time intervals. The relative position of continuous spectra branches on the complex plane of frequency effects on the method of analytical prolongation of the Laplace image of the potential. A method of analytical prolongation, connected with the introduction of a small frequency of collisions, is unfit in several cases. As an example con-sidered is the instability of surface waves of negative energy

[en] The parametric decay of a finite-extent cold-electron plasma wave (slow wave) was studied experimentally. Using a frequency of ω₀ > or approx. = 10ω/sub π/, it was found that the decay wave propagated along the pump wave rather than in the E₀ x B direction. This is in agreement with the recent theoretical predictions of finite-length stabilization

[en] The theoretical prediction of the enhancement of the maximum growth rate of the electromagnetic ion cyclotron instability, occurring in thermally anisotropic plasmas, in the presence of a cold plasma component was investigated by a computer simulation experiment. The plasma parameters used are B/sub p/ equivalent8πn/sub p , w/kT/sub parallel , p//B₀²=1 and kT/sub parallel , p/=25 keV. Three relevant cases were considered: case I, pure warm (n/sub p , c/=0) isotropic (A/sub p/mdT/sub perpendicular/,/sub p p//T/sub N, p/-1=0) plasma; case II, pure warm (n/sub p , c/=0) anisotropic (A/sub p/=0.5) plasma; and case III, a mixed warm-cold (n/sub p , c//n/sub p , w/=2) anisotropic (A/sub p/=0.5) plasma system. The results of the investigation confirm the linear theory of the enhancement of the instability. Moreover, they show the evolution of the unstable plasma systems through their quasi-linear and nonlinear stages. These results are relevant for active magnetospheric experiments to be performed in the near future

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[en] This paper deals with the theoretical investigation of low-frequency drift and trapped-particle instabilities in systems with magnetic shear, by analytic and numerical procedures and by computer simulations. In particular, results are presented for calculations which demonstrate: (1) the stability of both collisionless and dissipative drift eigenmodes at long radial wavelengths (k/sub r/rho/sub i/ less than 1) in a sheared slab (one-dimensional) geometry; (2) the presence and structure of drift and trapped-electron eigenmodes in an axisymmetric toroidal (two-dimensional) geometry; and (3) the nonlinear evolution and resultant anomalous transport from trapped-electron instabilities