Argon–seeded detachment during ELM control by RMPs in KSTAR
Ho‐Chul Shin, Junga Hwang, Youngnam Han, Giwook Shin, H. Lee, Kil‐Byoung Chai, Wonho Choe
Abstract
Abstract In this study, we demonstrate argon-seeded discharges that exhibited a detached divertor during the full suppression and mitigation of edge-localized modes (ELMs) by an International Thermonuclear Experimental Reactor-like, three-row resonant magnetic perturbation (RMP) configuration in KSTAR. During the ELM suppression phase, the peak heat flux on the divertor target was successfully reduced from 1.6 MW m −2 –0.5 MW m −2 via argon seeding. Further, the ion saturation current densities corresponding to the particle fluxes on both targets were reduced by more than 50%. During the RMP grassy-ELM regime, a further reduction to 0.1 MW m −2 in the divertor heat load was successfully achieved. A highly localized radiation zone near the X -point was also observed during divertor detachment. The calculated degree of detachment based on the two-point model increased to levels of approximately 3 and 2.3 for the outer target and inner target cases, respectively. These results provide valuable information regarding the effect of mid- Z impurities on RMP-detachment-compatible discharges.