Staebler et al. THE ROLE OF ROTATION IN TOKAMAK INTERNAL TRANSPORT BARRIERS The Role of Rotation in Tokamak Internal Transport Barriers*

Internal transport barriers have been observed in several tokamak operating regimes. A model of the energy, particle, and toroidal momentum transport due to drift wave turbulence is shown to form internal transport barriers due to E £B rotational shear. The power threshold for the transport barrier to form is found to be lowered by peaking of the power deposition or density proflle near the magnetic axis in agreement with experimental trends. Toroidal momentum injection counter to the current is predicted to lower the power threshold if the thermal ion density is peaked on axis, but an internal transport barrier can form even without toroidal rotation in either direction due to the density and temperature gradient contributions to the E £B rotational shear