[en] The diagram. where besides quasilinear interactions radiation-resonance interactions not considered before are taken into account, is used to explain entrainment currents in tokamak observed experimentally. It is shown that the resonance region can be widened if they are taken into account, and in this case the gap between the low phase velocity and thermal electron velocity decreases. Besides radiation resonance interactions, caused by a linear resonance, those, which are caused by a nonlinear resonance (induced scattering), are also taken into account. It is shown that contribution of induced scattering to radiation resonance interactions can provide

[en] It is shown that ion cyclotron range of frequency (ICRF) waves can induce fast convective radial transport of energetic ions in a tokamak geometry without affecting the background ion transport. Poloidally inhomogeneous ICRF waves with directional parallel wave vectors are needed; otherwise, a new parallel flow of the energetic ions has to be present

[en] The problem on dispersion of the MHD-waves on a small sphere has been considered on the basis of the integral equations of magnetic hydrodynamic with the Green time function. Both inner and outer MHD-potentials are studied and used to investigate fields of rates both out of the sphere and inside it for various cases of time-varying geometry of the sphere and small disturbance of the MHD-fields

[en] Abstract only

[en] Radial oscillations of a pinch plasma under an alternating external magnetic field are analyzed numerically. The external magnetic field consists of a constant bias field and a periodically alternating field. On the assumption that the plasma is confined in a thin cylindrical annulus and plasma conductivity is infinite, the non-linear equation of motion is solved numerically by Runge-Kutta-Gill (RKG) method. The solution of the equation is shown in phase space, including Poincare map. Poincare map is utilized to specify the oscillations. The frequency of oscillations is estimated by Fast Fourier Transform (FFT) spectral analysis. From the results of the analysis, stable radial oscillations make almost periodic oscillations and have several modes, including an eigenfrequency of radial oscillations, a frequency of the external field and their higher harmonics. The stable-unstable diagram is shown for typical parameters. It is also shown by the linear analysis using the perturbation method that unstable solutions occurred at specified parameters are caused by resonance. (author)

[en] The linear generation of electrostatic waves in a homogeneous, collisionless, unmagnetized plasma with two Maxwellian electron components, one drifting with respect to the other is investigated. The ions are assumed to be infinitely massive. It is shown that such a system may be unstable to a beam mode rather than the well-known Langmuir mode, if the drifting electron component is sufficiently dense and has a sufficiently low temperature. This 'electron-beam instability' is driven by the free energy in the particle distribution, and the associated phase velocity is greater than the electron thermal speed. The dispersion characteristics of the electron-beam instability and the Langmuir instability at the critical drift velocity for wave growth are determined for a wide range of parameters. The results of this investigation are applied to electron beams producing hard X-ray emission in solar flares, and it is argued that such beams may be unstable to the generation of electrostatic waves at frequencies below the electron plasma frequency. (author)

[en] From the analysis of the symmetries of the derivative nonlinear Schroedinger (DNLS) equation, a new constant of motion is obtained, which may be formally considered as a charge and which is related to the helicity of the physical system. From comparison of these symmetries and those of the soliton solutions, conclusions are drawn about the number of constraints that must be imposed and the way a Liapunov functional must be constructed in order to study the solitons' stability. The relationship between the stability with respect to form and the symmetries that are broken by the soliton solutions is examined. The analysis is completed with some numerical simulations: the DNLS equation is solved taking a slightly perturbed soliton as an initial condition and study its temporal evolution is studied and it is found that, as expected, they are stable with respect to form. (author)

[en] It is shown that the predictions of a numerical code (ANTENA) and the data of wave field measurements in the Phaedrus-B tandem mirror are consistent (±25%) for right-handed (B-vector_-) wave fields and less so (±40%) for left-handed (B-vector₊) wave fields in the plasma core, and that they disagree for B-vector₊ fields near the column edge. Shorting out or reduction of the wave azimuthal electric fields by limiters is the probable cause of this discrepancy. The ICRF fluctuating wave B-vector fields are shown as |B-vector| contour maps in the r-z plane, where the B-vector₊ data peak at a smaller radius than predicted. The waves are characterized by different dominant axial wave numbers for the left- and right-handed circularly polarized fields. (author). 28 refs, 20 figs, 1 tab

[en] The effects of an ambipolar field on the stability of electrostatic drift waves in sheet plasma are investigated numerically. The analysis is based on an integral equation in the wave number space derived from the profiles of Gaussian density and parabolic ambipolar potential. The ambipolar field dependence of the eigenfrequency and eigenfunction of the drift waves is obtained. It is found that the drift waves are stabilized for a storng ambipolar potential of both the hill-type and well-type. The stabilization is due to the ion Landau damping caused by the velocity shear effect of the E x B drift. Purely growing. (zero real frequency) drift modes are also found in the case of a hill-type ambipolar potential. (author)

[en] We show that acoustic waves in a weakly ionized collisional plasma in the one-dimensional case are governed by a Korteweg-de Vries equation. Solitary sound wave solutions can thus be found. (orig.)