Modeling of Small-sized ELMs in Detached Divertor Plasmas

Self-consistent modeling of edge plasma transport and deuterium wall inventory including multiple transient events was performed with the multi-physics 2-D transport code UEDGE-MB-W. In agreement with experimental data trends on DIII-D, the modeling results show that relatively small-sized and frequent type-I Edge Localized Mode (ELM) events, which are typical for high-power H-mode discharges with strong deuterium gas-puff fueling on this tokamak, are not burning through the formed detached plasma in the inner and, with further increase in fueling, in the outer divertor. In the latter case, the divertors are filled by sub-eV, high-density, strongly-recombining and highly impurity contaminated plasma. Time-dependent experimental data supporting the view that volumetric plasma recombination is enhanced during small-sized ELMs penetrating into the detached plasma are discussed and the confirmatory results from UEDGE-MB-W modeling are presented. ((c) 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)