Effects of flow shear on the ion temperature gradient modes in a high β plasma slab

Abstract

The integral eigenmode equations derived previously for the study of drift instabilities in a sheared slab plasma with arbitrary β (plasma pressure/magnetic pressure) are extended. These equations are used to investigate the effects of flow shear on the ion temperature gradient driven (ITG) modes. It is found that the destabilizing effect of a parallel velocity shear, V0′, is weakened by the finite β effect, especially in case of weak magnetic shear. However, the perpendicular velocity shear, VE′, still effectively stabilizes these modes even in high β regions. A large enough VE′ can completely stabilize the ITG mode at arbitrary β. In addition, the effect of VE′ is highly enhanced in weak magnetic shear regions. When the parallel flow coexists with the perpendicular flow, the comprehensive flow effect depends on the relative sign of these velocity shears. The modes with higher growth rates may be stabilized by a smaller VE′ for V0′VE′>0.