Scaling of the sawtooth repetition time from simulations with reduced MHD equations, and comparison with experiments in the Frascati Tokamak

The authors propose a scaling of the sawtooth repetition time for Ohmic discharges. This scaling has been obtained from simulations with reduced magnetohydrodynamic equations together with a simple profile consistent transport model. The choice of a profile consistent perpendicular thermal diffusion coefficient allows the scaling of the sawtooth repetition time to be obtained in terms of the diffusion coefficients and the safety factor at the edge, thus generalizing the scaling given by Vlad and Bondeson (Nucl. Fusion 29 (1989) 1139). The scaling is in good agreement with the experimental results for Ohmic discharges in the Frascati Tokamak.