The problem of bifurcation of a free boundary equilibrium is reconsidered in a simple model. We find which combinations of specified parameters result in a non-unique solution and find the resulting bifurcation point. By including reversed current solutions, the model sheds some light on the equilibrium βp limit obtained in previous analytic and numerical models.

The transmission and reflexion coefficients are calculated for the coupling of an ordinary polarized wave to the Z mode when the angle of incidence is near the critical angle.

It is shown that the combined effect of resistivity and thermal conductivity is responsible for the existence of marginal stationary modes in a cylindrical current-carrying plasma, under the influence of a shearless magnetic field. These modes occur in the tokamak approximation and for low wavenumbers. In the nonlinear theory they give rise to large-scale stationary convection.

The ion temperature history of the plasma fireball in TRISOPS IIX has been measured by comparing the time-resolved neutron yield from a D–D reaction and a D–T reaction. This measurement results in a reading of ion temperature that is independent of any assumptions of plasma density or fireball volume. The results verify and clarify previously reported TRISOPS parameters. In a separate set of measurements using a D–D reaction, the ion temperature was determined by comparisons of Doppler broadening and neutron yield. It was found that the ion temperature rises in 5 μs to 6 keV with a corresponding density of 1015 ions cm3. After 8 μs it falls rapidly to 1 keV as the density rises to 1017 ions cm–3. The 1 keV temperature is held for about 20 μs. These temperatures and densities yield an equilibration time for ions and electrons that is long compared with the duration of the experiment.

This paper deals with non-isothermal plasmas in which each species is described by Grad's thirteen-moment approximation. A theoretical framework, which includes a generalized Ohm's law and an ambipolar diffusion law, is used to treat energy dissipation resulting from ‘Motional’ interactions between the species. The frictional forces consist of a momentum relaxation force together with a ‘thermal force’ that occurs, in the presence of heat flow, partly because of the dependence of the collision frequencies on temperature. Detailed results are obtained for binary plasmas and for partially and fully ionized ternary plasmas. Our formalism is then compared with the technique used by Demetriades & Argyropoulos to study dissipation in thirteen-moment plasmas. The effects of thermal forces are illustrated by considering situations in which the drift contribution to the electronic relative thermal flux vector predominates over the thermal flux vector itself. Then, for binary plasmas and for ternary plasmas that are not too lightly ionized, the thermal forces increase the resistivity by a factor of about 5/2.

Using the Zakharov equations in their Fourier-transformed form, we consider the development of the modulational instability (MI) both for the monochromatic and the finite-width cases. In the static approximation and considering a monochromatic Langmuir wave which is coupled only to a single pair of Stokes and anti-Stokes Langmuir perturbations, we show that the resultant set of equations is integrable and we discuss the analytical solution of these equations. We show how a finite-width driver will lead to a threshold for the MI. We compare our results with those obtained by other authors.

We show what corrections have to be made to the equations of ideal magneto-hydrodynamics when there is fast-time-scale turbulence present in a magnetized plasma. We show how the dispersion relations for the ideal Alfvén and magnetoacoustic MHD normal modes are modified when such turbulence is present. Finally, we discuss the relation of our work to that of other authors.

The theory for potential surface wave fluctuation spectra in cold, inhomogeneous, magnetized plasmas is reconsidered, adopting a transition probability approach. A fluctuation dissipation relation is derived, which is valid for general density profiles and which reduces to the familiar fluctuation dissipation theorem for homogeneous plasmas. Significant corrections to previous work are found. Particular spectra are calculated for the special case of a magnetized plasma with a one-dimensional inhomogeneity.

The transport of neutrals in the outermost region of a tokamak plasma has been studied using kinetic theory. Analytical expressions for the density profiles of hydrogen and impurity neutrals are obtained. It is shown that the inclusion of recombination increases the density of hydrogen neutrals in the blanket region by orders of magnitude. It is also found that the major contribution to the impurity neutral density, for impurities which have a resonant mutual charge exchange with hydrogen, comes from mutual charge exchange for moderately dense plasmas whereas for dense plasmas this comes from recombination.

The propagation of a strong normal shock wave into a quiescent mixture of nitrogen gas seeded with small, spherical inert dust particles is studied. While crossing the shock front, the gaseous phase of the suspension experiences a sudden change in temperature, pressure, density and velocity. (These changes can easily be evaluated using the Rankine-Hugoniot relations.) The solid phase of the suspension (dust) is initially unaffected by the shock wave. As a result, immediately behind the shock front, one phase of the suspension (the nitrogen gas) is in a state of relatively high temperature and low velocity while the other (the dust) is in a state of relatively low temperature and high velocity. Owing to these differences in temperature and velocity, intense heat transfer and viscous interactions between the two phases take place leading eventually to a new state of equilibrium that is reached farther downstream of the shock front. The flow field where these interactions take place, the relaxation zone, is solved numerically. It is shown that the spatial extent of this zone is strongly affected by the mass concentration of the dust in the suspenson and its physical properties (size, density and specific-heat capacity). These parameters also affect the post-shock equilibrium suspension properties. It was found that increasing the dust concentration results in a shorter kinematic relaxation zone, higher post-shock suspension pressure, density and temperature, and lower velocity, as compared to a similar pure-gas case. Increasing the dust particle density or its diameter results in a longer relaxation zone and a higher post-shock equilibrium suspension pressure, density and temperature. Changes in the dust specific-heat capacity affect the extent at the thermal relaxation length and the suspension temperature and density; they do not affect the extent of the kinematic relaxation length or the post-shock suspension pressure and velocity. For the range of dust concentration, size, density, specific-heat capacity and shock-wave Mach number investigated, the kinematic relaxation zone is always longer than the thermal relaxation zone.

The plasma models used in analytical or numerical studies exhibit, mainly for practical reasons, symmetry reducing the dimensions of the space. It is not obligatory that the restrictions on the dynamics and the chosen form of the electrostatic interactions should correspond to the same symmetry and this introduces the concept of a d (dynamic), d' (electrostatic) model with d' ≥ d. We show that the crucial parameter is d' – d. For d' – d = 0, the model exhibits both at low and at high temperature the same characteristic plasma frequency. At high temperature we recover the Vlasov limit and the plasma acts as a high-pass filter. For d' – d = 1, the two frequencies (purely collective at high temperature and ‘crystal’ frequency at very low temperature) are different, while in its high temperature (Vlasov) limit the plasma acts as a low-pass filter. Finally if d' – d ≥ 2 there is no longer a Vlasov limit for all values of temperature and density. These properties are obtained through a systematic use of the homothety transformations and a search for the corresponding invariants.

The propagation of small-amplitude hydromagnetic waves in a cold plasma mixed with hot electrons is investigated using the first order CGL equations for electrons. It is assumed that in an equilibrium state the electrons consist of two components, cold electrons and hot electrons with bi-Maxwellians. Propagation properties of hydromagnetic waves are analysed by use of phase speed and refractive index surfaces, polarization, and the amplitude ratio between perturbed density and magnetic field. It is shown that the existence of cold electrons affects the properties of hydromagnetic waves through finite frequency corrections only when the temperature anisotropy exists; and that the existence of cold electrons diminishes the resonance angle and the critical angle at which the polarization sense changes from left-handed to right-handed, and also weakens the tendency of intermediate waves to follow the lines of force of the static magnetic field.

General properties of the eigenvalues of Schaper (1983), concerning the continuum of eigenvalues on p. 7, needs correction. The solutions in the distributional sense of the eigenvalue problem (5.3), will be given for two cases. The first case has been solved by A. Lifshitz and E. Fedorov and concerns continuous eigenvalues. In the second case, the solution for the points of accumulation of discrete eigenvalues is discussed.