The effect of the radial electric field on neoclassical flows in a tokamak pedestal

Abstract

Conventional formulae for neoclassical flows become inapplicable in subsonic tokamak pedestals with poloidal ion gyroradius scales since the associated strong radial electric field modifies the background ion orbits. The discrepancy has been measured to be substantial in the banana regime on Alcator C-Mod. We demonstrate that new expressions for the poloidal ion flow in the pedestal, that include the effect of the background electric field, are consistent with the boron impurity flow measurements in Alcator C-Mod.