Evaluation of toroidal torque by non-resonant magnetic perturbations in tokamaks for resonant transport regimes using a Hamiltonian approach

摘要

Toroidal torque generated by neoclassical viscosity caused by externalnon-resonant, non-axisymmetric perturbations has a significant influence ontoroidal plasma rotation in tokamaks. In this article, a derivation for theexpressions of toroidal torque and radial transport in resonant regimes isprovided within quasilinear theory in canonical action-angle variables. Theproposed approach treats all low-collisional quasilinear resonant NTV regimesincluding superbanana plateau and drift-orbit resonances in a unified way andallows for magnetic drift in all regimes. It is valid for perturbations ontoroidally symmetric flux surfaces of the unperturbed equilibrium withoutspecific assumptions on geometry or aspect ratio. The resulting expressions areshown to match existing analytical results in the large aspect ratio limit.Numerical results from the newly developed code NEO-RT are compared tocalculations by the quasilinear version of the code NEO-2 at lowcollisionalities. The importance of the magnetic shear term in the magneticdrift frequency and a significant effect of the magnetic drift on drift-orbitresonances are demonstrated.