First results examining the compatibility of RMP ELM suppression with the radiating divertor in DIII-D

Abstract

We report on recent DIII-D experiments that integrate edge localized mode (ELM) suppression using resonant magnetic perturbations (RMPs) with divertor heat flux reduction under radiating divertor conditions. Our results illustrate the limitations in maintaining ELM suppression at gas puffing levels that were representative of good puff and pump operation in previous experiments without RMP. The electron pressure gradient in the pedestal (∇Pe) increased steadily during gas puffing and ELMs returned once ∇Pe reached values consistent with the peeling–ballooning stability limit, as determined by edge stability analysis. Even with this return of ELMs, a radiating divertor with RMP generated higher levels of total radiated power (∼40%) than comparable standard ELMing discharges without RMP at the same density. Differences in the accumulation of the seed argon in the core plasma between RMP and non-RMP during puff and pump were less than 20%.