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22-27 October 2018
Mahatma Mandir Conference Centre
Asia/Kolkata timezone
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Test of the ITER-like RMP configurations for ELM-crash-suppression on KSTAR

26 Oct 2018, 08:30
20m
Mahatma Mandir Conference Centre

Mahatma Mandir Conference Centre

Gandhinagar (nearest Airport: Ahmedabad), India
Oral EXS - Magnetic Confinement Experiments: Stability EX/7-TH/5 Active ELM Control

Speaker

Prof. Yongkyoon In (Ulsan National Institute of Science and Technology (UNIST))

Description

KSTAR has demonstrated a divertor heat flux broadening during edge-localized-mode (ELM)-crash-suppression using ITER-like 3-row resonant magnetic perturbation (RMP) configurations for the first time. Over the last couple of years, we have established a robust methodology to fully suppress ELM-crashes using low-n RMPs. To address the ITER relevant ELM control, a systematic exploration of various RMP configurations at lower q95 plasmas led us to accomplish RMP-driven, ELM suppression down to q95 = 3.3 [1]. As long as the mode-locking at low q95 is avoided and a quick recovery of the wall conditioning (e.g. cryo-pumping or divertor gas-puffing) is secured, the access to the targeted q95 (~ 3) for ITER is foreseen to be feasible in KSTAR. Taking full advantage of 3-row in-vessel control coils (IVCC) in KSTAR, rather than 2-rows in other devices, a series of intentionally misaligned RMP configurations have been investigated for ELM-crash-suppression. The ITER-like 3-row RMPs were found to have broadened the divertor heat flux in the vicinity of outer strike point, while the 2-row has rarely affected the near scrape-off-layer (SOL) heat flux despite a little broadened profile change in the far-SOL area [2]. Since the main focus of divertor heat flux dispersal would be the redistribution of the peaked near-SOL heat flux, such contrasting 3-D heat flux broadening must be similarly attributable to the choice of 3-rows in ITER, instead of 2-rows. Since such broadening characteristics could be completely different in partially detached plasmas in ITER [3], KSTAR has conducted an investigation of whether RMP-driven, ELM-crash-suppression would be compatible with detached plasmas. Although a fully detached plasma under RMP has not been obtained yet, we were able to greatly reduce heat flux at q95=3.8 using n=2 RMPs in high density plasmas [4]. Overall, the new lessons we have learned would be directly relevant to the successful ITER RMP research, while resolving any uncertainty associated with 3-row RMPs that could be further exploited in KSTAR. References: [1] Y. In et al, APS-DPP invited talk titled “Tamed Stability and Transport using Controlled Non-axisymmetric Fields in KSTAR” (2017) [2] A. Loarte, Y. In et al, to be published (2018) [3] R. Pitts, private communications (2018) [4] J.W. Ahn et al, APS-DPP (2017)
Paper Number EX/7-1
Country or International Organization Korea, Republic of

Primary author

Prof. Yongkyoon In (Ulsan National Institute of Science and Technology (UNIST))

Co-authors

Dr Alberto Loarte (ITER Organization) Dr Gunyoung Park (National Fusion Research Institute) Prof. Hyeon K. Park (UNIST) Dr Hyungho LEE (National Fusion Research Institute) Dr Jaehyun Lee (National Fusion Research Institute (NFRI)) Dr Jong-Kyu Park (Princeton Plasma Physics Laboratory) Dr Joon-Wook Ahn (Oak Ridge National Laboratory) Dr Kimin Kim (National Fusion Research Institute (NFRI)) Dr Minwoo Kim (UNIST) Dr YoungMu Jeon (National Fusion Research Institute)

Presentation Materials

Paper