Beam emission spectroscopy (BES) measurements of ion-scale density fluctuations in the MAST tokamak are used to show that the turbulence correlation time, the drift time associated with iontemperature or density gradients, the particle (ion) streaming time along the magnetic field, and the magnetic drift time are consistently comparable, suggesting a ‘‘critically balanced’’ turbulence determined by the local equilibrium. The resulting scalings of the poloidal and radial correlation lengths are derived and tested.
