In some Tokamak experiment [1], it is observed that the application of ECRH could affect the local plasma rotation. What may be the possible mechanism to this effect? In their paper this question seems not well explained and remains unclear. In pure ohmic discharge, could ECRH alone change the local plasma rotation where its power deposits?

[1] R M McDermott et al 2011 Plasma Phys. Control. Fusion 53 035007, Effect of electron cyclotron resonance heating (ECRH) on toroidal rotation in ASDEX Upgrade H- mode discharges.