Effects of finite gradient B drift on collisional boundary layer analysis for neoclassical toroidal plasma viscosity in tokamaks

Abstract

The effects of finite gradient B drift are included in the collisional boundary layer analysis to improve the accuracy of the neoclassical toroidal plasma viscosity in tokamaks that have error fields or magnetohydrodynamic activities present. Depending on the sign of the electric charge of the species and that of the radial electric field, the effects of finite gradient B drift can either reduce, if the E × B drift is in the same direction of the gradient B drift, or enhance, if these two drifts are in the opposite direction, the magnitude of the neoclassical toroidal plasma viscosity. Here, E is the electric field and B is the magnetic field. However, because the gradient B drift depends on the effective pitch angle, the net effects have to be properly weighted by integrating over the particle energy.