The dispersion relation of linear waves in a non-relativistic, collisionless and homogeneous magnetized plasma is solved by numerical methods. Both electrostatic and electromagnetic waves with frequencies from below the ion gyrofrequency to above the electron gyrofrequency are studied for all angles of propagation. Modes occurring in a cold plasma as well as waves dependent on thermal effects are included. Dispersion surfaces, that is plots of frequency versus wave vector components, are presented for some plasma models. This presentation shows all interesting waves clearly and reveals how different modes are related. The dispersion surfaces can be used as an aid, for example, when comparing wave observations and theory, and they may also help to avoid confusing nomenclature.

This paper deals with the evolution of a small initial perturbation superimposed on a plane whistler wave due to self-modulation in the case of propagation along the external magnetic field.

Nonlinear evolution of a large-amplitude relaxation oscillation in an unstable plasma diode is investigated by a computer simulation using a particle model. The oscillation is closely related to double-layer dynamics accompanied by a negative potential dip on the low-potential tail. A vortex is formed in the electron velocity phase space during the potential evolution, which causes a topological rearrangement of the phase space in the high-potential plasma.

A new fluid-theory derivation of the time-dependent ponderomotive force is presented in the oscillation-centre representation. We show that the velocity renormalization adopted in this paper is equivalent to the oscillation-centre representation and is the velocity required so that the mean density obeys the continuity equation exactly. We also show that previous fluid theory results may be recovered by adopting a different velocity renormalization and by redefining the ponderomotive force.

We analyse high-frequency electrostatic solitary surface waves that propagate along a plasma cylinder in the presence of a constant axial magnetic field. The width of such a solitary wave, which is found to be inversely proportional to its amplitude, is expressed as a function of the magnitude of the external magnetic field.

We investigate the low-frequency azimuthal oscillations on a non-neutral magnetized electron column of very low density. A perturbation analysis of the slow mode of the rigid rotator equilibrium is developed to illustrate the nature of large-amplitude fundamental-mode oscillations. The results of this theoretical analysis show two important characteristics: firstly, as the perturbation amplitude is increased the wave form ceases to be purely sinusoidal and shows period doubling. Secondly, above a certain threshold, all harmonics of the wave grow and the wave breaks. The results of the former are compared with a simple electron beam experiment and are found to be in good qualitative agreement.

The plasma expansion into the wake of a large rectangular plate immersed in a single-ion, collisionless, streaming plasma has been investigated in the laboratory. Several characteristics of the process involved in ‘plasma expansion into vacuum’ that have been predicted theoretically were observed, including the creation and motion of a rarefaction wave disturbance; the creation and motion of an expansion front; and the acceleration of ions into the wake at speeds above the ion-acoustic speed. The expansion was limited to early times; i.e. a few ion plasma periods, by the combination of plasma drift speed and vacuum chamber size. This prevented detailed comparison with self-similar theory, but results are in good agreement with numerical simulations and other laboratory experiments for the early time expansion. The conclusion is that the plasma expansion process is the dominant wake filling mechanism in the near wake of a body, whose potential is approximately the plasma space potential.

An electron charge is suddenly switched on while drifting through a warm collisional plasma. It acts thereafter with an arbitrary time-dependence. The evolution of the plasma, initially at rest, is considered in two and three dimensions. A general solution is first established for drift-modified slow plasma modes and then employed in subthermal drift analysis. Its abrupt switch-on causes the electron charge to release, during subthermal drift, a fully symmetric thermal front Г which subsequently expands ahead of it into an undisturbed receding expanse. A transversely symmetric response develops inside Г. On switch-off, the drifting charge releases another thermal front Г0 which also precedes it but trails non-concentrically behind Г. Plasma response continues after switch-off. Response properties between Г and Г0 differ strikingly from those inside Г0. Applications are next considered, first in three dimensions, for a subthermal pulsating electron with a generally complex frequency ω. The prepermanent state response inside Г comprises an axisymmetric dominant component ø∞ plus a spherically symmetric transient component øtr. ø∞ acquires the frequency ω. øtr has amplitudes dependent on and wave crests independent of both frequency ω and drift; it suffers a fast (slow) ω–independent temporal attenuation in a collisional (collisionless) plasma. The geometrical drift wave structure of ø∞ is closely examined for real ω and a collisionless plasma. Every energy surface associated with ø∞ nucleates at the electron; from there, it evolves slower than a phase surface, which eventually ‘disappears’ past Г. The leading energy surface, which nucleated at switch-on, develops permanently inside Г; it serves as an energy front that seals off the energy sustaining ø∞ since switch-on. Finally, the two-dimensional evolving drift field of an activated antenna line is computed.

An analytical formulation is presented for envelope-type solutions of intense polarized electromagnetic waves propagating in cold unmagnetized plasmas. Induced charge separation is fully taken into account and nonlinearities due to mass variation of both electrons and ions are included. Localized solutions are found for the case of subluminous wave phase velocity. The spectrum of solutions (dependence of wave amplitude on the free parameters in the theory, phase velocity and frequency) is discussed and compared with previous analytical and numerical results.

With positive ambipolar potential, ion non-resonant neoclassical transport leads to increased particle confinement times. In certain regimes of filling pressure, microwave powers (ECRH and ICRH) and positive potential, new folds can now emerge from previously degenerate equilibrium surfaces allowing for distinct C, T, and M modes of operation. A comparison in the equilibrium fold structure is also made between (i) equal particle and energy confinement times, and (ii) particle confinement times enhanced over the energy confinement time. The nonlinear time evolution of these point model equations is considered and confirms the delay convention occurrences at the fold edges. It is clearly seen that the time-asymptotic equilibrium state is very sensitive, not only to the values of the control parameters (neutral density, ambipolar electrostatic potential, electron and ion cyclotron power densities) but also to the initial conditions on the plasma density, and electron and ion temperatures.

Amplitudes of electromagnetic waves with combination frequencies, radiating from a narrow inhomogeneous layer of the magnetoactive plasma due to interaction of the surface waves, are determined. The method used allows for discontinuity of the tangential components of the wave electric field at the combination frequencies at the plasma boundary.