Effect of Sheared Magnetic Field on E × B Drift Instability in Plasma

Abstract

The influence of the magnetic shear on ion drift waves has been investigated for plasmas in the plane slab geometry with a density gradient. A differential equation is derived to describe the mode structure along the density gradient. The magnetic shear localizes the mode around a mode-rational surface, which is perpendicular to the magnetic field. The non-local growth rate turned out to be smaller as compared to the shearless one. The magnetic shear stabilizes long wavelength modes (kρi < 1 ), whereas it destabilizes, as the mode tends toward the short wavelength region, where the density gradient provides a destabilizing effect for the magnetic shear-driven resistive drift mode. However, the effect due to the collision frequency is significantly low in our analysis. The combined effects of E×B flows and the magnetic shear enhance the confinement over a narrow radial region with an internal transport barrier, where stability is attained.