A theoretical model for the generation of co-current rotation by radio frequency heating observed on Alcator C-Mod

A theoretical model is presented which shows generation of a co-current directional central toroidal rotation by a nondirectional on-axis ion cyclotron heating in the Low-mode plasmas of Alcator C-Mod tokamak [I. H. Hutchinson et al., Phys. Plasmas 1, 1511 (1994)]. It is shown that a net-inward nonambipolar transport of resonant ions can induce such a rotation. The net-inward transport is a result of the passing ion dominant transport process in Alcator C-Mod. The opposite horizontal orbit shift between co- and counter-passing ions makes the wave absorption asymmetric in k∥.