In this paper we generalize the formalism developed by Balescu and Paiva-Veretennicoff, valid for any kind of weak turbulence, for the determination of all the transport coefficients of an unmagnetized turbulent plasma, to the case of a magnetized one, and suggest a technique to avoid finding the inverse of the turbulent collision operator. The implicit plasmadynamical equations of a two-fluid plasma are presented by means of plasmadynamical variables. The anomalous transport coefficients appear in their natural places in these equations. It is shown that the necessary number of transport coefficients for describing macroscopically the magnetized turbulent plasma does not exceed the number for the unmagnetized one. The typical turbulent and gyromotion terms, representing dissipative effects peculiar to the magnetized system, which contribute to the frequency-dependent transport coefficients are clearly exhibited.

Expressions for the current response operators of first and second order are calculated for a fluid plasma with isotropic pressure terms. The unperturbed state is an arbitrary space and time dependent solution of the basic equations. The response operators are given in a form which shows explicitly the mathematical structure behind the approximate conservation of wave energy in resonant wave interactions. The coefficients in the coupled mode equations are expressed in terms of these response operators.

This paper is concerned with the Boltzmann collision integral for the one-particle distribution function of a test species of particle undergoing elastic collisions with particles of a second species which is in thermal equilibrium. A previous paper studied this expression as a function of the mass ratio for the two species of particle when the test particle distribution function was isotropic in velocity space; this work generalizes that analysis to anisotropic distribution functions by expanding the distribution function in tensorial spherical harmonics. First the limit of zero mass ratio is considered: this simplifies the calculation dramatically. There is no contribution to the collision integral from the zeroth-order spherical harmonic in this limit. Then the main calculation shows how to find the terms arising from the existence of a finite mass ratio as an ascending power series in this quantity, and evaluates for each spherical harmonic the next term, linear in mass ratio. This is checked for two special cases: that of an isotropic distribution function, when the expression reduces to Davydov's form, and that arising from a cross-section inversely proportional to the collision velocity, when a comparison with the exact solution of the associated eigen problem can be made. As in the isotropic case, an exact representation of the collision integral as an expansion in mass ratio must include some terms non-analytic in this quantity and vanishing more quickly than any positive power: it is shown how these arise in the present formalism. The formulae derived here have applications to the transport theory of electrons and light ions in a predominantly neutral gas as governed by the Boltzmann equation.

The behaviour of the crossfield current-driven ion-acoustic instability in the presence of a sheared magnetic field and a density gradient is investigated theoretically in the limit in which growth due to inverse Landau damping is small. The shear damping rate is found and the critical shear length shown to vary as (mi/me)⅓ and as ((VD–CS)/CS)–⅔.

The linear growth rate of the crossfield current-driven ion-acoustic instability is obtained for any equilibrium particle velocity distribution function of the type . Quasi-linear theory is then used to investigate the saturation of the instability. Several associated features, namely, particle diffusion in velocity space, anomalous resistivity, energy distribution and electron and ion heating rates are evaluated for a Maxwellian distribution. Finally, a brief comparison is made with the heating rates associated with the electron cyclotron drift instability.

The Hα resonant scattering diagnostics applied to the tokamak UNITOR is described. The measurements yield the density distribution of excited hydrogen atoms as a result of plasma-wall interaction processes and background plasma parameters. Special regard has been given to the influence of recycling processes.

The mean electromotive force generated by random Alfvén waves in a collision-less plasma is evaluated taking into account mean magnetic field gradients. It is shown that the mean electromotive force associated with a magnetic shear of the mean field and the helicity spectrum function of the random velocity field exists and has a component parallel to the mean magnetic field when it is generated by random waves propagating along the mean magnetic field and by statistically anisotropic random waves propagating in arbitrary directions. The results are applied to the magnetospheric substorms.

The mean electromotive force generated by random hydromagnetic waves is calculated by using Fourier analysis methods for the cases of an incompressible Hall plasma and a compressible plasma with finite β. It is shown that in the case of a Hall plasma the α effect can exist in the interaction between two waves which propagate in opposite directions and have different phase velocities and several new β–terms are produced by the Hall effect, while in the case of a compressible plasma the α–effect can exist only in the interaction between the Alfvén mode and the fast or slow magneto-acoustic mode, and not between the fast and slow magneto-acoustic modes. The results are discussed in the context of the substorms in the earth's magnetosphere.

The mean electromotive force produced by random hydromagnetic waves in a collisionless plasma is investigated taking into account non-uniformities in the mean magnetic field, fluid velocity and plasma density. It is shown that the mean electromotive force associated with gradients in mean quantities and the helicity spectrum function of the random velocity field exists and has a component parallel to the mean magnetic field which is associated with field-aligned gradients in mean quantities and density gradients parallel to the mean flow. The results are discussed in the context of the field-aligned currents in the earth's magnetosphere.

In this paper we develop similarity solutions for the problem of nonlinear Landau damping of Alfvén waves. These solutions which are applicable to power-law wave spectra illustrate not only the basic feature of the damping process, namely that short-wavelength waves decay more rapidly than long-wavelength waves, but also how the damping depends on the initial strength of the power spectrum and its distribution in wavenumber.

Magneto-acoustic oscillations were excited in a non-uniform, current-carrying plasma column. Measurements of the oscillating axial magnetic flux at a number of excitation frequencies were used to determine the equilibrium plasma properties. In agreement with previous theoretical studies, the radial profile of the plasma density is shown to be accurately determined, while it is not possible to obtain detailed information on the radial profile of the equilibrium magnetic field.

The Petschek model for incompressible reconnexion has been put on a firm mathematical foundation in an earlier paper by Soward & Priest, who discovered a ‘local’ similarity solution for the process. The present paper extends that analysis to compressible reconnexion, in which the previous Alfvén waves are replaced by slow magneto-acoustic shocks of switch-off type. By contrast with a previous suggestion, it is found unnecessary to include intermediate waves standing ahead of the slow shocks. The maximum reconnexion rate is typically half of Petschek's stated value, though faster rates are achieved when the external gas pressure is sufficiently low.

The equilibrium of a plasma cylinder confined by means of a steady axial magnetic field, Bα, and a transverse magnetic field, Bω, which rotates about the axis of the cylinder is analysed using a two-fluid model. It is shown that the electron fluid is tied to the rotating field provided that

The rotating field does not impart a steady azimuthal motion to the ions provided that However, the ion fluid acquires a steady azimuthal velocity due to electron-ion collisions. A self-consistent radial electric field is produced; this field plays an important role in establishing the steady ion flow.