Anomalous transport in the second stability regime

Operation in the second stability regime can manifest itself as an improvement of confinement with β. This will be the case if the main cause of confinement deterioration with increasing β is pressure-driven instabilities. Stellarators are well suited to the experimental study of these effects because of their ability to operate with zero toroidal current, eliminating one source of free energy. On the basis of resistive pressure-gradient-driven turbulence theory, an improved confinement regime that is accessible at relatively low values of β is predicted for the Advanced Toroidal Facility (ATF). (author)