Stability and transport of parallel velocity shear driven mode with negative magnetic shear

The linear and quasilinear behavior of the drift-like perturbation with a p arallel velocity shear is studied in a sheared slab geometry. Full analytic studies show that when the magnetic shear has the same sign as the second derivative of the parallel velocity with respect to the radial coordinate, the linear mode may become unstable and turbulent momentum transport increa ses. On the other hand, when the magnetic shear has opposite sign to the se cond derivative of the parallel velocity, the linear mode is completely sta bilized and turbulent momentum transport reduces. (C) 2000 American Institu te of Physics. [S1070-664X(00)01203-9].