Breaking up-down symmetry with magnetic perturbations in tokamak plasmas: Increase of axisymmetric steady-state velocities

Plasma rotation plays a crucial role on heat and particle confinement in tokamaks. To consider this issue, we numerically compute the axisymmetric steady states of the visco-resistive magnetohydrodynamic equations, including the non-linear (v · λ) v term using the finite element method. Imposing external n = 0 magnetic perturbations offers a way to break the natural up-down symmetry of the system and produce a net toroidal flow. Using realistic parameters, some numerical results indicate that n = 0 perturbations of the magnetic configuration may be used to increase n = 0 steady-state speeds and promote tokamak plasma confinement while preserving axisymmetry.