On offset toroidal rotation in NTV

Tokamak has toroidal symmetry and symmetry breaking via application of non-axisymmetric field produces disccipation of toroidal momentum by NTV [1] and produces offset toroidal rotation [2]. Callen explained NTV physics and origin of offset toroidal rotation plainly without impurity [3] and with impurity [4]. For impurity, same toroidal rotation for ion and impurity is assumed in [4], which is not always correct as shown by Kim [5]. I have revisited this subject and found revised formula for offset toroidal rotation [6]. It is shown that offset toroidal rotation of bulk ion originates from poloidal thermal heat flow qi is different from simple Callen’s formula. It is also found that similar magnitude of rotation speed difference between ion and impurity is expected especially in high poloidal beta regime, where plasma current is carried largely by the bootstrap current and is relevant for steady state operation of tokamak.