RESISTIVE INTERCHANGE MODES IN NEGATIVE CENTRAL SHEAR TOKAMAKS WITH PEAKED PRESSURE PROFILES

Resistive interchange modes can be driven unstable by large pressure g radients in the negative central magnetic shear (NCS) region of advanc ed tokamaks. Localized stability analysis reveals that the resistive i nterchange stability criterion (D-R less than or equal to 0) is violat ed in this region, and unstable n = 1 localized resistive magnetohydro dynamic (MHD) modes are computed using the resistive MHD code MARS. In DIII-D NCS plasmas, these instabilities appear as bursting MHD activi ties, constituting the first identification of resistive interchange i n a high temperature tokamak experiment. These bursts also appear to p lay a role in triggering disruptions.