The geodesic transfer effect on zonal flows in tokamak edge turbulence

Detailed computations of tokamak edge turbulence in three-dimensional, globally consistent flux tube geometry show an inhibition of the standard scenario in which zonal E×B flows generated by the turbulence should lead to transport barrier formation. It is found by comparison to slab geometry and by analysis of the energetics that the zonal flow energy is depleted by toroidal coupling to the pressure through the geodesic curvature. Edge transport barriers would then depend on the physics of a self-consistent equilibrium including neoclassical forcing effects as well as the turbulence