The detailed behaviour of a beam of light propagating through a fully ionized plasma is studied near the critical density. Transient effects in the laser beam and plasma are included by taking into account, in a self-consistent manner, the proper motion of the plasma in an intense electromagnetic field. Parameters of the laser beam and plasma conditions are studied that prove most beneficial in providing a uniform deposition of energy. The behaviour of the light beams near the critical density at the three wavelengths 1054 nm, 527 nm and 351 nm are compared.

A theoretical analysis of acoustic-like modes in a plasma consisting of two kinds of ions with different temperatures has been performed using fluid equations. The electrons are assumed to form a dynamic neutralizing background, and their perturbation has been neglected – which is permissible for k2λ2De ≫ 1. The analysis shows that an acoustic-like mode appears to propagate as a normal mode when the hotter ion concentration is very large compared with that of the colder ions.

A whistler wave propagating through a preformed magnetospheric duct is susceptible to growth/amplification by an electron beam. The interaction is non-local and could be of Čerenkov or slow-cyclotron type. First-order perturbation theory is employed to obtain the growth rate for flat and Gaussian beam densities.

The problem concerning the appropriate form for the nonlinear frequency shift arising from slow density modulations of electrostatic surface waves in a semi-infinite unmagnetized plasma is reconsidered. The spatial dependence of the wave amplitude normal to the surface is kept general in order to allow for possible nonlinear attenuation behaviour of the surface waves. It is found that if the frequency shift is expressed as a function of the density and its gradient then the result is identical with that of Zhelyazkov (1987b), who assumed a linear exponential attenuation behaviour.

Reflection of ion-acoustic waves from the ion sheath in front of the separation grid in a double-plasma device has been investigated experimentally. The plasma potential φ of the source plasma was controlled relative to that of the target plasma. When eφ < κΤe, where Τe is the electron temperature, no reflection was observed. The reason for this is that ions are drifting towards the grid with the Bohm velocity, i.e. the ion-acoustic velocity. When eφ > κΤe the reflected wave consists of the ion-acoustic wave and the ion beam mode. The reflection coefficient for the ion-acoustic wave is about unity. This high efficiency is due to reflection of the ions themselves.

This paper presents a derivation of the nonlinear equations governing the space–time evolution of magnetic electron drift waves in an inhomogeneous magnetoplasma. The equilibrium electron pressure gradient is maintained by the gradient of an external magnetic field. An oscillatory instability is shown to arise. The existence of magnetic electron drift vortices is discussed and the limitation on the vortex speed due to the external magnetic field is pointed out.

Analytic modelling of laser-produced plasmas has generally been restricted to one-dimensional flow. Multi-dimensional hydrodynamic approximations are available, and are explored in this paper. Two configurations are examined. The explosive mode in which the entire body of material is uniformly heated is treated by the self-similar form, and the aspect ratio of the resulting expansion is determined. Ablative flows can be approximated by the hybrid model, and the self-regulating flow from a solid target can be calculated in this way.

Ion-acoustic waves in sheet plasmas, which are of thickness of order of the ion Larmor radius ρi, have been investigated numerically. The frequency range considered is less than the ion cyclotron frequency ωci. An integral equation in wavenumber space is derived from the linearized Vlasov-Poisson equations and analysed numerically. Eigenfrequencies and eigenfunctions of the wave have been studied systematically by varying the plasma thickness, plasma density, electron-to-ion temperature ratio and parallel wavenumber. Electron-acoustic waves are found when the parallel wavenumber is very small (e.g. k∥ρi = 0·005) and the electron and ion temperatures are comparable.

The modulational instability of a whistler wave propagating along an external magnetic field is investigated, taking into account the dispersion of the low-frequency modulations. The dispersive effects are significant if the modulation frequencies Ω are comparable to or greater than the ion cyclotron frequency ωci. It is shown that in this case there are four unstable branches: the long-wave modulational instability and three others with much larger growth rates. At Ω≪ωci the latter correspond to fast magnetic sound, Alfvén and slow magnetic sound branches.

The mode conversion of an electrostatic whistler wave into a Bohm–Gross mode at plasma resonance is analysed for a magnetized plasma with a longitudinal density gradient (i.e. ∇n0 X B = 0). It is found that a whistler incident upon plasma resonance from inside the plasma converts, without producing a reflected wave, into a short-wavelength Bohm-Gross mode that carries energy down the density gradient away from resonance. The detailed structure of the electric field near the resonance is found analytically. It is shown that the production of the Bohm-Gross wave by mode conversion can be described by a model of plasma resonance driven by a k = 0 electric field (i.e. the capacitor plate model). The relation between the driver amplitude and the amplitude of the incident whistler is derived.

The transport of plasma under the influence of a significant flow velocity in a toroidal stellarator has been modelled using an efficient numerical scheme based on ‘propagators’. The particle density has been calculated in a poloidal cross-section from the fluid particle conservation equation, using a flow velocity and a diffusion coefficient derived from experimentally obtained values. The formation of hollow density profiles during ECH has been examined, by varying the flow velocity v(r,θ) of the bulk of the plasma while ensuring that (its component in the minor-radial direction, averaged over poloidal angle θ) is consistent with experiment. A radial flow does not seem to account for the very hollow profiles observed in experiment. Hollownesses of between 1·5 and 5 were obtained for other plausible forms of v(r, θ).

In this paper we determine the asymptotic behaviour of the spectral function for two types of waves generated in a turbulent plasma: plasma waves generated by a kinetic electron beam instability, and lower-hybrid waves. It is shown that the wave spectrum behaves in the lowest-order approximation as K–6 and K║–3 in the respective cases (where k and k║ are the wavenumber and the wavenumber parallel to the magnetic field) and is bounded below by an appropriate value. The distribution function is evaluated self-consistently in each case.

A recently described numerical theory for obtaining the Sagdeev and real potential profiles of stationary wave forms in a plasma consisting of double-Maxwellian electrons and two or more species of warm ions is used for the study of solitons in such a plasma. The effects of ion temperature and light-ion concentration on rarefactive ion-acoustic soliton profiles in a double-ion plasma obtained with this large-amplitude theory are compared with those predicted from a Korteweg–de Vries equation. Application of the theory to the work of Nakamura and co-workers is discussed, and we draw attention to ion thermal effects.

The flow fields induced by spherical blast waves propagating into dusty gases are investigated numerically. In the case of a moderate blast wave the gaseous phase is assumed to be perfect, while for strong blast waves real-gas effects are accounted for. The effects of the dust loading ratio and the initial energy used to generate the blast on the suspension properties are investigated and discussed in detail. Owing to the fact that the physics involved inside the exploding charge is very complicated, the present solution is appropriate for simulating the flow induced by the blast wave outside the exploding sphere only.

The stochastic non-resonant energization of ions in non-sinusoidal coherent plane-polarized magnetosonic waves is investigated. It is found that, as in the case of sinusoidal magnetosonic waves, the process does not follow quasi-linear theory, i.e. it is a diffusion in velocity space, but with a diffusion coefficient D ∝ ν–α, α ≈ 1, instead of D ∝ ν–3. Moreover, it is found that the presence of strong harmonics lowers the stochasticity threshold of the wave amplitude by as much as one order of magnitude (depending on the form of the power spectrum), but at the same time it suppresses the diffusion rate of the ions in velocity space. Our results indicate that waves with a saw-tooth wave form are the most efficient for ion energization.

This paper explores the properties of Rossby-type electrostatic electron plasma waves at frequencies very much less than the electron gyrofrequency but very much greater than the ion gyrofrequency. Such waves represent the electron counterpart of ion Rossby waves, which propagate at frequencies very much less than the ion gyrofrequency in a plasma in which the ambient magnetic field possesses a spatial gradient perpendicular to its line of action. This feature simulates the ‘β-effect’ that operates in the classical atmospheric Rossby wave: the wave dynamics associated with both ion and electron Rossby waves are structurally similar to those associated with wave perturbations in a rotating fluid, where the β-effect arises from a spatial gradient in the Coriolis acceleration. It is shown that this plasma β-effect gives rise to a ‘new’ mode of the Rossby type, and in addition considerably modifies the conical wave propagation properties characteristic of the electron cyclotron mode. The highly dispersive and anisotropic nature of these waves is described in terms of the topology of the wavenumber surfaces concomitant with plane-wave solutions of the wave equation for the system as a whole.