Poloidal spin-up of tokamak plasmas from poloidal asymmetry of particle and momentum sources

Abstract

Transport equations for particle density, toroidal angular momentum, and poloidal rotation are derived in the presence of strong particle and momentum sources in general axisymmetric toroidal geometry. It is shown that the state with no poloidal rotation is unstable on flux surfaces where the local particle source rate is sufficiently poloidally asymmetric and, roughly, more rapid than the damping rate of poloidal rotation from magnetic pumping. In agreement with earlier results, it is also shown that a toroidally injected momentum source can drive poloidal rotation if the momentum deposition is poloidally asymmetric. Thus poloidal rotation could be induced in tokamaks by asymmetric particle fueling.