Radiatively tamed divertor thermal loading in resonant magnetic perturbation (RMP)-driven, ELM-crash-suppressed plasmas

Abstract

Edge-localized-modes (ELMs) suppression by non-axisymmetric resonant-magnetic-perturbation (RMP) provides the way to
reach high performance fusion plasmas without a threatening level of transient heat fluxes to the walls of fusion devices. The
application of RMP, however, strongly modifies the heat flux pattern onto in-vessel components in contact with the plasma
(especially the divertor) leading to local “hot spots”. Radiative dissipation by partially ionized species (impurities and
deuterium) lowers the heat flux peaks on the walls but has been poorly compatible with such RMP-driven, ELM-crash-suppression.
Here, we show how KSTAR has radiatively tamed divertor thermal loading down to more than a factor of 7 in the off-separatrix region without losing ELM-crash-suppression using ITER-like, three-row, RMP configurations, demonstrating its sustainment even in a partially detached
plasma in the outer strike point, as desired for ITER.

Dynamic control of divertor heat flux during n = 4 resonant magnetic perturbation edge localized mode suppression by small variation of q 95 in EAST

“…On the other hand, the application of RMPs for ELM suppression leads to the creation of non-toroidally symmetric divertor power fluxes. In toroidally asymmetric conditions, the power loads to the divertor are still limited to 10-20 MW m −2 [3], and their reduction by divertor radiation, such as gas puffing or impurity seeding, remains unresolved [12]. These fluxes will challenge the divertor material if the pattern of the heat fluxes remains stationary [13].…”