Dynamics of sheared flow driven drift-Alfven waves in nonuniform plasmas

A two-fluid model is used to derive a set of nonlinear equations governing the dynamics of low-frequency drift-dispersive Alfven waves in a nonuniform plasma containing equilibrium density gradients and sheared equilibrium plasma flows. In the linear limit, we present a local dispersion relation, which is analyzed in some interesting limiting cases. It is found that sheared equilibrium flows can cause instability of the Alfven waves even in the absence of a density inhomogeneity. Furthermore, it is demonstrated that possible stationary solutions of the nonlinear equations governing the dynamics of dispersive Alfven waves with sheared equilibrium flows in cold plasmas can be represented in the form of coherent vortical structures. The results of these investigations should improve the understanding of current filamentation and vortex motions in space and laboratory plasmas.