EFFECT OF A POLOIDAL SHEAR-FLOW ON THE PROBABILITY OF ACCESSING THE MULTIPLE SATURATED STATES IN THE RESISTIVE INTERCHANGE INSTABILITY

A systematic study based on 400 nonlinear single-helicity calculations with random initial perturbations shows that multiple nonlinear state s exist at saturation. They are characterized by different values of t he poloidal wave number ot the dominant mode in the spectrum. As a con sequence, the saturated states have different levels of fluctuations a nd different self-consistent poloidal flow profiles. The presence of a n external shear poloidal flow does not always directly change the sat uration level of the fluctuations. For low shear flows, it can increas e the probability of accessing the high saturated levels. For very hig h values of the flow shear, however, there is suppression of the fluct uations. A curvature poloidal flow reduces the saturation level of eac h state and increases the probability of accessing the low fluctuation levels. Transitions between saturated states accompanied by sudden ch anges in flow profile have been observed. Most of the observed transit ions are from a low to a high level of fluctuations.