Observation of ELM suppression in hybrid discharges using n = 3 magnetic perturbations on DIII-D

Abstract

Large type-I edge localized modes (ELMs) are completely suppressed in hybrid discharges for the first time by applying an edge resonant perturbation (RMP) using an internal coil set with toroidal mode number n = 3. This is an important advance in developing hybrid discharges as a baseline operating scenario for ITER. In these experiments on the DIII-D tokamak, the ELM suppression lasts for ∼1 s in plasmas with normalized beta up to βN = 2.5 (volume average beta up to β = 3.4%) and a fusion performance factor as high as , which equals the value for the Q = 10 scenario in ITER. A strong interaction between the 3/2 neoclassical tearing mode and the RMP, which slows the pedestal toroidal rotation, limits the achievable βN and the duration of ELM suppression.