STABILITY OF SMALL-SCALE PERTURBATIONS IN DIFFERENTIALLY ROTATING PLASMAS
The initial-value problem for linearized equation describing small-scale flute modes in plasmas with nonuniform rotation is solved. It is shown that the differential rotation modifies qualitative characteristics of interchange bubbles such as their shape and the temporal dependence of amplitude. The radial wavelength of perturbations decreases with time, while their amplitude evolves according to a power law, instead of the usual exponential behavior. The radial contraction of the wavelength leads, on the one hand, to the decrease of the plasma displacement, but, on the other hand, to the increase of the perturbed electric field. As a result, the energy of perturbations increases even in the case when the amplitude of perturbed potential stays constant. Small-scale perturbations become stable if the ion gyroviscosity is taken into account.