The effect of fast-ion losses due to the toroidal field ripple on the toroidal rotation is studied through numerical simulations. The simulations are carried out by utilizing a multi-fluid one-dimensional transport code, TASK/TX, with a ripple transport model suitable for implementing one-dimensional transport codes. Simulation results are qualitatively consistent with the experiments in JT-60U. It is shown that the return current associated with the outward radial fast-ion current due to the ripple loss flows inwards in the bulk plasma and the resultant torque drives the plasma toroidally in the counter direction of the plasma current. The equilibrium value of the toroidal rotation velocity is determined by the balance between the perpendicular viscosity and the total torque.
Fast-ion transport and toroidal rotation response to externally applied magnetic perturbations at the ASDEX Upgrade tokamak