[en] An exact solution for the oscillating two-stream instability is presented for the case where the initial pump profile has a constant phase. The main features exhibited by the solution are (i) a very rapid partial pump depletion when the scaled pump energy is approximately π/2, 3π/2, 5π/2, etc., (ii) filamentation of a square pump profile undergoing any such partial depletion, and (iii) stability when the scaled pump energy is just above nπ, and instability when it is just below nπ

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[en] The results of simulations of the lower-hybrid drift instability in a neutral sheet configuration are described. The simulations use an implicit formulation to relax the usual time step limitations and thus extend previous explicit calculations to weaker gradients, larger mass ratios, and long times compared with the linear growth time. The numerical results give the scaling of the saturation level, heating rates, resistivity, and cross-field diffusion and a demonstration by comparison with a fluid electron model that dissipation in the lower-hybrid drift instability is caused by electron kinetic effects

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[en] Presented numerically is an apparently paradoxical nonlinear process that a two-stream instability is stabilized by inhomogenizing or ''grooving'' an initially homogeneous plasma, not by limiting the stream which is the direct cause of the instability. For a relatively wide and slow electron stream, the instability is shut off by reducing the speed to the threshold value (ion sound speed), as is naturally expected. For a narrow and fast stream, however, the instability is shown to be stabilized by the grooving effect

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[en] Understanding the static balance of forces in a hypothetical stationary, steady-state magnetotail configuration is central to our understanding of planetary magnetotail dynamics, even though the actual planetary magnetotails may rarely if ever attain such a steady state. We are not likely to achieve an understanding of the observed departures from equilibrium if we do not first understand the nature of the equilibrium itself, albeit hypothetical. The condition of magnetohydrostatic equilibrium implies tight constraints on the degree of anisotropy that is supportable in a magnetotail field geometry. If the plasma pressure tensor is assumed to be gyrotropic at the tail midplane (z = 0), then equilibrium requires that it also be nearly isotropic there, with P_{perpendicular0}/P_parallel0 in the range 1 ± δ², where δ ∼ 0.1 is the ratio of the normal field component at the symmetry plane to the field strength in the tail lobe. The upper and lower limits are essentially equivalent, respectively, to the marginal mirror and firehose stability conditions evaluated at z = 0, which have been invoked previously to limit the degree of anisotropy in the plasma sheet. 21 refs., 1 fig