Nonlinear saturation effects associated with the generation of electron plasma waves by two high-frequency electromagnetic waves, beating at a frequency nearly equal to the electron plasma frequency, are studied. A fluid model including collisions, frequency mismatch and relativistic mass variation is used. It is shown that for large-amplitude driving waves a transition to chaos can occur, leading to plasma wave breakdown. The results may be relevant to the beat-wave current drive in tokamak devices and to beat-wave particle accelerators.

Through rescaling and obtaining invariant equations, we study the expansion of charged particles immersed in a time-varying magnetic field B(t) = B0(1+Ωt)–β. We develop the theory for a configuration of point particles confined in a plane with an initial cylindrical symmetric configuration. It is found that the system expands according to (1+Ωt)2β/3 for β ≤ 1 and it is conjectured that in a properly rescaled space and time, it reaches asymptotically an inhomogeneous (in space) Brillouin flow with rigid rotation at half the cyclotron frequency (ω = ½ωc). Particular attention is given to the ‘pivot’ case β = 1. It is shown then that the radius of the rescaled configuration is now dependent on the ratio Ω/ωc, and grows indefinitely with time for Ω/> 3.2–3/2;. Numerical experiments are presented which confirm these theoretical predictions and conjectures. Finally, the properties of this system are compared with those of single-particle and ‘rod’ electrostatic models.

Whitham's averaged Lagrangian principle, and the Low Lagrangian are used to derive the averaged Lagrangian for slowly varying electrostatic and electromagnetic wave packets in dispersive Vlasov plasmas. From the averaged Lagrangian, the stress tensor and wave-momentum densities are derived for the total wave-particle system. For a specific division of these total quantities into wave and background parts, time-dependent ponderomotive forces in Vlasov plasmas are derived from a momentum conservation theorem. We also show that the wave-induced magnetization current can be derived by the averaged Lagrangian method.

The lower-hybrid instabilities in high-beta (ratio of plasma to magnetic pressure) plasmas driven by ring-ion distributions in velocity space are investigated. A dispersion equation including electromagnetic effects is derived. In the low-beta limit, analytic expressions are obtained which illuminate the physical nature of the instabilities. The complete dispersion equation is solved numerically as a function of ring speed and plasma beta for several types of ring distribution. Electromagnetic effects are important for relatively energetic rings even in the low-beta regime, suppressing growth rates and shifting the angle of propagation to more oblique angles. Stabilization by thermal effects is also discussed. Application of these results to the Earth's bow shock, AMPTE, comets and solar flares is suggested.

A ring distribution of ions in velocity space can generate electrostatic waves which propagate predominantly along an ambient magnetic field at frequencies comparable with the ion plasma frequency. A dispersion equation which accounts for these waves is presented, and solved analytically and numerically. It was found that ion-acoustic-like waves are excited in a plasma even if the electron temperature is comparable with the ion temperature under the assumption of an anisotropic ion distribution.

A nonlinear model equation describing ballooning modes for β of the order of the inverse aspect ratio and including magnetic shear is derived. For the special case of circular concentric flux surfaces, we obtain an approximate dispersion relation, including finite Larmor radius effects, and show the possibility of explosive instability in the nonlinear regime. The results are shown to remain valid in the presence of a low-density hot-ion constituent.

It is shown that the combined effect of resistivity and thermal conductivity leads to convection in a cylindrical current-carrying plasma, under the action of a shearless magnetic field. In contrast to the case of part 1, these modes occur for large wavenumbers and Bθ≫ Bz The conditions, however, are the same as before. From this fact it is then conjectured that convection takes place for any wavenumber, determined only by the actual value of B0/Bz.

Numerical solutions were obtained by Forbes, Priest & Hood (1982) for the resistive decay of a current sheet in an MHD fluid. To check the accuracy of the numerical solutions, a linear, analytical solution was also deived for the regime where diffusion is dominant. In a subsequent reinvestigation of this problem an error in the linear, analytical solution has been discovered. For the parameter values used in the numerical solution this error is too small (≲ 2%) to produce any significant change in the previous test comparison between the numerical and analytical solutions. However, for parameter values much different from those used in the numerical solution, the error in the linear solution can be significant.

A new kind of surface oscillation, which can exist when the usual surface waves are absent because of resonant absorption, has been studied for a non-uniform plasma slab. Special attention is paid to the influence of the boundaries on the eigenfrequency spectrum.

The theory of particle aspect analysis is extended to the drift wave in the presence of an inhomogeneous magnetic field. The dispersion relation and growth rate of the wave are evaluated and discussed when the magnetic field gradient is directed opposite to the density gradient. The plasma under consideration is assumed to be anisotropic and the effects of temperature anisotropy on the dispersion characteristics and growth rate of the wave are also studied. The dispersion relation and the growth rate are evaluated for the space plasma parameters.

A closed set of CGL equations, modified to include heat flux correction, is used to study the firehose and mirror instabilities in a rarefied plasma. A significant feature which has been noticed is that some of the terms contributed by the higher-order moments are of the same order as the terms in the unmodified CGL equations. We study the effect on the firehose and mirror instabilities of those terms which persist in the limit of vanishing heat flux vector. It is found that these terms lead to a new criterion for mirror instability. The criterion for hose instability, however, remains unaffected.

A relativistic treatment of the plasma dispersion functions and of the dielectric tensor for electron cyclotron electromagnetic waves is given for non-thermal plasmas where the electron distribution function can be represented as a combination of Maxwellians with arbitrary drifts along the magnetic field.

A new stellarator ripple-transport mechanism is predicted at the low collision frequencies characteristic of ions in a reactor plasma. A heuristic argument is used to derive an approximate diffusion coefficient whose magnitude, scaling and range of applicability agree well with the results of Monte Carlo calculations. The proposed diffusion coefficient is independent of collision frequency within its range of validity, which encompasses the parameters of most ions in a reactor. Its magnitude is smaller than previous estimates for the diffusion coefficient in this range, but larger than the diffusion coefficients in all other low-collision-frequency regimes. An explanation of the form of the diffusion coefficient is given in terms of analytic theory of ripple transport.