A study of impurity rotation behaviour in the TJ-I tokamak

Poloidal and toroidal rotation velocities of impurity ions have been measured with spatial resolution in the TJ-I tokamak from the shift of impurity lines. The behaviour of poloidal rotation with regard to plasma-density, plasma current and safety factor has been studied. Plasma core impurities rotate poloidally in the electron diamagnetic drift direction, with a few exceptions, and with a different velocity for each species. In contrast intrinsic edge impurities may rotate in the opposite direction for averaged densities below 1.5*1013cm-3. Whereas a central peaking impurity rotates poloidally like a rigid body, other species peaking at mid-radii exhibit sheared poloidal rotation. These results have been related to changes in the plasma potential. The behaviour of impurity rotation in the TJ-I tokamak is discussed in the context of the standard neoclassical theory.