Stability of kinetic ballooning and drift type modes in tokamaks with negative shear

Stability analysis carried out for a tokamak discharge with negative shear indicates that a kinetic ballooning mode driven by ion magnetic drift resonance persists in a shear window, -0.4 less than or similar to s less than or similar to -0.1, provided alpha (ballooning parameter) greater than or similar to 0.1. In negative shear, the toroidal ion temperature gradient mode is stabilized by finite beta and nonequilibrium ion temperature, T-i greater than or similar to 2.5 T-e. The trapped electron drift mode appears to be most persistent, particularly in the long wavelength regime where coupling to the ion acoustic transit mode is predominant without suffering ion Landau damping. Stabilization of the mode requires a strong negative shear, s < -0.6.