This paper deals with the problem of classification of the two-stream instability for hot plasmas. The method is based on the criterion of Fainberg, Kurilko & Shapiro (1961). The basis of the analysis is the ‘resonance’ distribution, but a modified resonance distribution, leading to better results, is also investigated. The stability limit, classification into absolute and convective instabilities, as well as asymptotic growth rates are given for some chosen values of stream densities and temperatures, and arbitrary stream velocities. A method for finding the maximum temporal growth rates is also outlined.

Ion-acoustic waves propagating in a collision-free, gravity-supported plasma in a static magnetic field are studied with a linearized Vlasov equation. The dispersion relation is derived in the limit of vanishing electron to ion mass ratio and wavelength much larger than the Debye length. From this dispersion relation it is shown that the well-known fluid dynamic steepening tendency of waves propagating in the direction of decreasing density is competing with the effect of Landau damping. Depending on the ratio of electron and ion temperatures, the direction of propagation and the strength of the static magnetic field, waves of wavelengths of the order of the scale height or even greater are shown to be damped. Several special cases are discussed.

The effects of dissipation due to a week firehose instability on steady planar flow of a collisionless plasma are investigated on the basis of the quasi-linear fluid equations. Dissipation terms remain non-linear even within the perturbation theory, and their effects tend to resemble relaxation effects in an ordinary reacting gas rather than ordinary viscous dissipation. As an example, a steady half-jet flow with aligned magnetic field is considered. It is found that the disturbed field decays within a finite distance for some upstream conditions, but grows without limit for others.

‘MHD Rankine-Hugoniot equations applied to earth's bow shock’

by J. D. Mihalov, C. P. Sonett and J. H. Wolfe

J. Plasma Physics (1969), vol. 3, part 3, pp. 449–463

The bottom entry of column 2, Table 2, page 455, should read ‘–20’ instead of ‘20’. Recent work suggests the possibility of a systematic error as large as ˜ –3 deg in ø(‘spacecraft’ co-ordinates) of Table 1, page 453. The calculations have been repeated with the ø values decreased by 2·8 deg, with the result that none of the conclusions of the paper are changed since the detailed numerical results are not significantly different.

On page 463, the fifteenth of the list of references should read:

Ness, N. F. & Taylor, H. E. 1969 Annals of the IQSY, 3, 366.

On the same page, the fifth to the last of the list of references should read:

Wilcox, J. M. 1969 Solar Flares and Space Research, p. 294 (edited by C. de Jager and Z. Švestka). Amsterdam: North-Holland Publishing Co.