Mitigation of divertor heat flux by high-frequency ELM pacing with non-fuel pellet injection in DIII-D

the DIII-D team

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18 Scopus citations

Abstract

Experiments have been conducted on DIII-D investigating high repetition rate injection of non-fuel pellets as a tool for pacing Edge Localized Modes (ELMs) and mitigating their transient divertor heat loads. Effective ELM pacing was obtained with injection of Li granules in different H-mode scenarios, at frequencies 3–5 times larger than the natural ELM frequency, with subsequent reduction of strike-point heat flux (Bortolon et al., Nucl. Fus., 56, 056008, 2016). However, in scenarios with high pedestal density (∼6 × 1019 m−3), the magnitude of granule triggered ELMs shows a broad distribution, in terms of stored energy loss and peak heat flux, challenging the effectiveness of ELM mitigation. Furthermore, transient heat-flux deposition correlated with granule injections was observed far from the strike-points. Field line tracing suggest this phenomenon to be consistent with particle loss into the mid-plane far scrape-off layer, at toroidal location of the granule injection.

Original languageEnglish
Pages (from-to)1030-1036
Number of pages7
JournalNuclear Materials and Energy
Volume12
DOIs
StatePublished - Aug 2017

Funding

Supported in part by U.S. Dept. of Energy under contracts DE-AC02-09CH114661 , DE-AC05-00OR227252 , DE-FC02-04ER546983 , DE-FG02-06ER54867 and DE-AC52-07NA273444 . DIII-D data shown in this paper can be obtained in digital format by following the links at https://fusion.gat.com/global/D3D_DMP .

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