Preliminary Study of the Magnetic Perturbation Effects on the Edge Density Profiles and Fluctuations Using Reflectometers on EAST

The resonant magnetic perturbation (RMP) coils have been successfully designed and installed on the Experimental Advanced Superconducting Tokamak (EAST). Using the reflectometer systems, the density profile and the density fluctuations during magnetic perturbations (MPs) phase have been investigated. During the experiments, two different cases are studied separately: steady MPs and rotating MPs. In both cases, a strongly density pump-out has been observed. In the steady MPs cases, an enhancement of the low frequency (<60 kHz) density fluctuations in H-mode phase has been observed. The plasma density boundary out-shifts ∼5% caused by the MPs. The pedestal density gradient is reduced by 50%, while the radial location nearly stays unchanged. In the rotating MPs, the line-averaged density, the D α emission at the divertor region and the spectrum of the density fluctuations are modulated. The results suggest that the low frequency (<60 kHz) density fluctuations may contribute to the strong density pump-out.