Two-dimensional nonlinear self-modulations of a high-frequency whistler wave propagating along an applied magnetic field in a plasma are investigated. We derive new, fairly broad, regions of modulational instabilities in directions oblique to the initial wave propagation with growth rates much greater than in the case of ‘parallel’ self-modulation. The largest growth rate appears to be for the angles corresponding to the parametric instabilities. Nonlinear solutions describing the envelope solitons propagating obliquely to the initial wave are also discussed. Our results are in qualitative agreement with recent experiments.

An investigation is made of the effect of an external growth-rate modulation on the saturation of a linearly unstable plasma wave by means of nonlinear Landau damping. Different ways of exciting the saturated system by suitable choices of modulation frequency are discussed and the characteristics of the resulting instabilities, like thresholds, growth-rates, maximum amplitudes and final saturation levels are determined.

We study the dispersion equation of drift waves in the presence of electron- plasma turbulence in a plasma with magnetic shear. We show that the shear stabilization can be cancelled out by a hot turbulent spectrum, even for a low level of turbulence, W/n0Te≪ 1.