Dispersion relations of plasma waves in a beam–plasma System are computed in the general case where the plasma and beam temperatures, and the; velocity of the beam, may be relativistic. The two asymptotic temperature cases, and different contributions of plasma or beam particles to wave dispersion are considered.

Temporal and spatial hydrodynamical instabilities and kinetic instabilities of plasma waves are considered for a relativistic beam–plasma System. The beam and plasma temperatures, and the beam velocity, may be relativistic. Instability conditions and growth rates are evaluated. An unusual case of kinetic stability inversion, for relativistic or dense beams, is discussed.

A relativistic study of the beat wave of two laser beams in a hot plasma is presented in the case where the modifications of the distribution function due to this beat wave are much smaller than the equilibrium distribution function. This situation corresponds to small laser energies or high plasma temperatures. The power-conversion efficiency of the laser beams is evaluated for different values of temperatures, laser energies and frequencies.

The magnetohydrodynamic stability of a streaming annular jet containing a very dense fluid cylinder and acted upon by inertial and electromagnetic forces, in the presence of a varying transverse magnetic field pervading a tenuous surrounding medium, is considered. A general dispersion relation is established and studied analytically, and the results are confirmed numerically. The magnetic fields are stabilizing or destabilizing for each of the symmetric (m = 0) and non-axisymmetric (m ≠ 0) modes under some restrictions. The streaming has a strong destabilizing character, and its influence is to enlarge the magnetohydrodynamic instability domains and shrink the stability domains. The thicker the dense fluid core, the greater the number of magneto-hydrodynamically stable states. Increasing the magnetic field intensity shrinks the unstable domains. The (in)stability situation is much worse for m ≠ 0. However, if the axial field intensity is sufficiently high and greater than the transverse field intensity, the destabilizing character of the model, in a few cases, may be suppressed. This occurs if the Alfvén-wave velocities interior and exterior to the annular jet are greater than the unperturbed fluid velocity.

A critical analysis of nonlinear waves in a non-isothermal relativistic plasma is performed using reductive perturbation theory. The plasma is assumed to contain two-temperature electrons. Higher-order corrections to the solitary wave are also computed, and the variations of the profile with respect to v/c, the two temperatures of the electrons, and the parameters bl, and bn characterising the non-isothermal nature are depicted graphically and com-pared with previous results.

The nonlinear evolution of lower-hybrid-drift waves in an inhomogeneous magnetized plasma with warm electrons and cold ions is considered. The effect of finite electron temperature on a soliton solution of the set of nonlinear equations is examined.

The solution of the linearized Vlasov–Poisson equations describing a projectile ion moving through a classical isotropic electron plasma is investigated analytically and numerically for a wide range of projectile velocities vp Extending the range of earlier computations considerably, our calculations were performed for velocities up to vp = 15vth, showing the wake field behind the ion for distances 0 ≤ d ≤ 200λD, where vth is the thermal electron velocity and λD the Debye length of the plasma. As a new feature, we demonstrate that the amplitude of the wake field in the region vp/vth ≤ d/λD ≤/23(vp/vth)3 is almost undamped, and only for larger distances from the ion does it take the 1/d behaviour shown in other work. Thus the wake field of a single ion persists for much longer than previously thought. The question of whether this effect could have practical consequences, for example, for ion-beam cooling, is briefly addressed.

A symmetric factorization of the velocity-dependent charge-exchange kernel (the so-called separable-kernel model) is used in the Boltzmann equation for neutral atoms to obtain an exact solution for a half-space plasma by the Wiener-Hopf method. This work generalizes earlier work employing constant, velocity-independent charge-exchange interactions to the case of an arbitrary velocity dependence of the Maxwellian averaged charge-exchange reaction rate. The effects of velocity dependence on the speed-angle distribution of escaping neutrals and the total charge-exchange rate in the half-space are shown to be significant. It is also shown how the Wiener-Hopf method can be applied to such problems with a realistic Maxwellian plasma background, without first approximating the ion distribution.

A new System of co-ordinates is found and a method developed to determine the toroidal equilibrium of plasmas with arbitrary current distribution and plasma cross-section. The method depends on knowledge of the equilibrium of a straight plasma column of similar cross-section and similar current distribution. A large aspect ratio is assumed. By successive approximations, better solutions can be obtained. An explicit formula is presented for the poloidal flux of a nearly circular plasma. This can be written in terms of a function related to the asymmetry of the poloidal field due to toroidality. The method works provided that there is only one magnetic axis.

A new analytical method is introduced to consider electrostatic surface waves propagating on a cold plasma. A very simple dispersion relation is derived for a plasma bounded by two dielectrics. Previous theory for solitary surface waves is also generalized.

Analytical expressions for the weakly relativistic dielectric tensor near the electron-cyclotron frequency and harmonies are obtained to any order in finite-Larmor-radius effects for a bi-Maxwellian distribution function. The dielectric tensor is written in ternis of generalized Shkarofsky dispersion functions, whose properties are well known. Relevant limiting cases are considered and, in particular, the anti-Hermitian part of the (fully relativistic) dielectric tensor is evaluated for two cases of strong temperature anisotropy.

A new theory for fast steady-state magnetic reconnection is proposed that includes many features of recent numerical experiments. The inflow region differs from that in the classical model of Petschek (1964) and the unified linear solutions of Priest & Forbes (1986) in possessing highly curved magnetic field lines rather than ones that are almost straight. A separatrix jet of plasma is ejected from the central diffusion region along the magnetic separatrix. Two types of outflow are studied, the simplest possessing an outflow magnetic field that is potential. The other contains weak standing shock waves attached to the ends of the diffusion region and either slowing down the flow (fast-mode shock) after it crosses the separatrix jet or speeding it up (slow-mode), depending on the downstream boundary conditions. A spike of reversed current slows down the plasma that emerges rapidly from the diffusion region into the more slowly moving downstream region, and diverts most of it along the separatrix jets. In the simplest case the outflow possesses no vorticity over most of the downstream region. The models demonstrate that both upstream and downstream boundary conditions are important in determining which regime of reconnection is produced from a wide variety of possibilities.

In a cold plasma the wave equation for solely compressional magnetic field perturbations appears to decouple in any surface orthogonal to the background magnetic field. However, the compressional fields in any two of these surfaces are related to each other by the condition that the perturbation field b be divergence-free. Hence the wave equations in these surfaces are not truly decoupled from one another. If the two solutions happen to be ‘matched’ (i.e. V.b = 0) then the medium may execute a solely compressional oscillation. If the two solutions are unmatched then transverse fields must evolve. We consider two classes of compressional solutions and derive a set of criteria for when the medium will be able to support pure compressional field oscillations. These criteria relate to the geometry of the magnetic field and the plasma density distribution. We present the conditions in such a manner that it is easy to see if a given magnetoplasma is able to executive either of the compressional solutions we investigate.