Temporal Evolution of Drift Alfv en Waves in an Inhomogeneous Plasma with Homogeneous Shear Flow

The temporal evolution of drift-Alfv en waves in a plasma ow with homogeneous shear is studied as an initial value problem without the use of spectral expansion in time. It is shown that the conventional modal structure of the drift-Alfv en instability (as well as drift and Alfv en waves) pertains only in the initial stage of its evolution. For larger times, non-modal e ects due to the velocity shear impede the development of the drift-Alfv en instability; the frequency increase caused by the shear ow brings the Alfv en wave phase speed close to the electron thermal speed where strong electron Lan-