Abstract
The coupling of the internal kink to an external m/=1/1 pertubation if studied for profiles that are known to result in a saturated internal kink in the limit of a cylindrical tokamak. It is found from 3D equilibrium calculations that, for A≈30 circular plasmas and A=3 elliptical shapes, this coupling of the boundary perturbation to the internal kink is strong; the amplitude of the m/n=1/1 structure at q=1 is large compared to the amplitude applied at the plasma boundary. It is proposed that this excitation, which could readily be applied with error field correction coils, be explored as a mechanism for controlling sawtooth amplitudes in high performance tokamak discharges. This saturated internal kink, resulting from small field errors in proposed as an explanation for the TEXTOR measurements of q0 and the distinction between sawtooth effects on the q-profile observed in TEXTOR and DIII-D.