Absorption by trapped particles is supposed to seriously hinder current drive by Alfvén waves. However, it is shown in this paper that the same effect is rather beneficial for the emergence of the radial electric field induced by these waves, which is important for creating and maintaining transport barriers in tokamaks.

The scattering of transverse electromagnetic waves by turbulent density fluctuations in a magnetized plasma in the presence of external pump fields is investigated. The case where a lower-hybrid pump wave decays into daughter and ion-cyclotron waves in a plasma with ion-temperature anisotropy is considered. The situation where an upper-hybrid pump wave parametrically excites modified convective cells and electron drift waves is also analyzed. The differential scattering cross-sections in the region above the parametric instability thresholds for these three cases are calculated.

The results of a previous work, which describes in the magnetohydrodynamic approximation Alfvén wings in nonuniform plasmas, are extended in order to consider more general variations of the background fields. As mathematical tools we use general curvilinear coordinates and stream functions. We prove the possibility of existence of Alfvén wings when the background fields have cylindrical or helical symmetry. For the former, the wings are cylinders, and for the latter, they have helicoidal form; this last includes the case of uniform background fields. We also obtain the relations among the different physical magnitudes in the wing.

Making use of the dielectric permitivitty of a solid state plasma obtained from linearizing a quantum hydrodynamic equation, volume and surface waves in cold semibounded plasma-like media and thin layers of solid state plasmas are investigated in the presence and absence of an external magnetic field. It is shown that quantum oscillation of free charged particles and its spatial dispersion even in cold plasmas lead to new spectra of collective oscillations. Furthermore, a new volume ion-acoustic-type wave is obtained with a quadratic dependence on the wavenumber in the long-wavelength limit. Moreover, it is shown that quantum oscillation affects the surface wave spectrum and extends it to a wider frequency region.

Generation of wake fields by a short electromagnetic pulse in a plasma with an inhomogeneous background magnetic field and density profile is considered, and a wave equation is derived. Transmission and reflection coefficients are calculated in a medium with sharp discontinuities. Particular attention is focused on examples where the longitudinal part of the electromagnetic field is amplified for the transmitted wave. Furthermore, it is noted that the wake field can propagate out of the plasma and thereby provide information about the electron density profile. A method for reconstructing the background density profile from a measured wake field spectrum is proposed and a numerical example is given.

In most studies, the properties of dust-acoustic solitons are derived from the first integral of the Poisson equation, in which the shape of the pseudopotential determines both the conditions in which a soliton may exist and its amplitude. Here this first integral is interpreted as conservation of total momentum, which, along with the Bernoulli-like energy equations for each species, may be cast as the structure equation for the dust (or heavy-ion) speed in the wave. In this fluid-dynamic picture, the significance of the sonic points of each species becomes apparent. In the wave, the heavy-ion (or dust) flow speed is supersonic (relative to its sound speed), whereas the protons and electrons are subsonic (relative to their sound speeds), and the dust flow is driven towards its sonic point. It is this last feature that limits the strength (amplitude) of the wave, since the equilibrium point (the centre of the wave) must be reached before the dust speed becomes sonic. The wave is characterized by a compression in the heavies and a compression (rarefaction) in the electrons and a rarefaction (compression) in the protons if the heavies have positive (negative) charge, and the corresponding potential is a hump (dip). These features are elucidated by an exact analytical soliton, in a special case, which provides the fully nonlinear counterpoint to the weakly nonlinear sech2-type solitons associated with the Korteweg–de Vries equation, and indicates the parameter regimes in which solitons may exist.

The nonlinear interaction between large-amplitude electromagnetic waves and electron-acoustic (EA) waves in a two-electron-temperature plasma is considered, taking into account the combined effects of the radiation pressure and the thermal force involving the differential Joule heating of the electrons caused by the electromagnetic waves. By employing a fluid approach, we derive a system of coupled equations for the electromagnetic waves and the EA waves; the latter are nonlinearly driven by the radiation and thermal forces. We have carried out a normal mode analysis of our nonlinearly coupled equations, and have derived a general dispersion relation that is useful for studying different types of parametric instabilities. A new class of modulational instability in the collision-dominated regime is identified. The implications for space and laboratory plasmas are pointed out.