Neoclassical toroidal plasma viscosity in the superbanana plateau regime for tokamaks

Abstract

Neoclassical toroidal plasma viscosity in the superbanana plateau regime induced by the broken toroidal symmetry in |B| resulting from the error fields or magnetohydrodynamic activities in tokamaks is calculated. The transport processes in this regime are dominated by particles that have vanishing bounce averaged precession frequency, i.e. by the resonant particles. The superbanana plateau regime becomes important when the E × B drift speed is comparable to or smaller than the ∇B drift speed. Here, E is the radial electric field, B is the magnetic field and B = |B|. The resonance occurs regardless of the sign of the radial electric field or the electric charge a species carries. The plasma viscosity and the transport fluxes in this regime are found to be independent of the collision frequency.