The interaction of rotating magnetic fields (RMFs) with a plasma is modelled in the linear approximation. A kinetic Hamiltonian model for the rf plasma conductivity is used. A radially inhomogeneous periodic cylindrical plasma with a rotational transform of the magnetic field is studied with parameters relevant to the dynamic ergodic divertor (DED) of TEXTOR. For the case of a finite electron diamagnetic velocity it is shown that the torque resulting from the RMF tends to bring the electron fluid approximately to the rest frame of this field. This result is in qualitative agreement with long mean-free path drift MHD theory. In contrast to that theory where a resonant behaviour is found at electron and ion diamagnetic frequencies, in the present kinetic analysis, the RMF frequency where the torque passes through zero is smaller than the electron diamagnetic frequency if there is an electron temperature gradient present. The relation of these results with recent experimental measurements of the DED-induced plasma rotation in TEXTOR is discussed.
Plasma stabilization by a high-frequency rotational field