Toroidal rotation in resonant regimes of tokamak plasmas due to non-axisymmetric perturbations in the action-angle formalism

摘要

Introduction Toroidal torque generated via neoclassical toroidal viscosity (NTV) [1, 2, 3, 4] caused by external non-resonant, non-axisymmetric magnetic perturbations (TF-ripples, error fields, perturbations caused by ELM mitigation coils away from resonant surfaces) has a significant effect on toroidal plasma rotation in tokamaks. Besides collisional transport regimes, an important role (in particular, in ASDEX-Upgrade [4]) is played by resonant transport regimes such as superbanana-plateau [1] or bounce and bounce-transit resonance [2] regimes where transport coefficients are independent of the (small) collision frequency. Here, a universal approach by the canonical Hamiltonian quasilinear formalism in action-angle variables [5] is presented. This approach is well developed for the general case of small electromagnetic perturbations in tokamaks (see e.g. [6]). The described treatment covers both trapped and passing orbits in a unified way and does not require any simplifications of device geometry. Numerical results of NTV evaluation in resonant transport regimes are presented and compared to references [1,3].