Neoclassical Transport and Poloidal Rotation at the L-H Transition

We address the question of establishing if, and under what physical and boundary conditions, the neoclassical transport is quantitatively capable of establishing high gradients in a narrow layer at the edge of an auxiliary heated tokamak plasma, and of driving poloidal rotation in the absence of external momentum input and vanishing parallel viscous stress, in a time scale of a few milliseconds. We observe that a torque for poloidal and toroidal acceleration with constant parallel flow is provided by the displacement current at third order of the adiabatic expansion. Combining neoclassical transport with a model of anomalous transport suppression we show the development, during a few milliseconds, of strong gradients in temperature, radial electric field and poloidal rotation at the edge, that are consistent in magnitude nd sign with observations.