Effect of the periodic ripple in an axial confining magnetic field on the Alfvén heating of a cylindrical plasma

In a uniform axial magnetic field, the structure of local Alfven resonance and the resonant absorption of RF power are governed by collisions, finite ion Larmor radius effects, and electron inertia. It is shown that, in a cylindrical plasma in a constant, periodically rippled, axial magnetic field, the structure of Alfven resonance and the absorption of RF power can strongly depend on the ripple amplitude. The conditions under which the effect in question is dominant are intrinsic, e.g., to the modular Wendelstein stellarators.