Temporal evolution of linear drift waves in a collisional plasma with homogeneous shear flow

Abstract

Temporal evolution of linear drift waves in a collisional plasma with a homogeneous shear flow is treated analytically. The explicit solutions for the linearized Hasegawa–Wakatani system of equations, as well as for linearized Hasegawa–Mima equation, are obtained for this case on the basis of the nonmodal approach. In the weak-collision regime, the homogeneous shear flow is found to be a factor impeding the development of the ordinary modal resistive drift instability. This instability is excited only in the case of a weak velocity shear. For a stronger shear, the nonmodal effects, such as the blocking of drift wave packets and the linear transformation of drift waves into convective cells, determine the temporal evolution of drift-like perturbations. A nonmodal solution is found in the limit of strong collisions or sufficiently strong flow shear. The solution at the asymptotically large time possesses a convective-cell pattern.