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22-27 October 2018
Mahatma Mandir Conference Centre
Asia/Kolkata timezone
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Comparative simulations of the plasma response to RMPs during ELM-crash mitigated and suppressed phases in KSTAR

25 Oct 2018, 08:30
4h
Mahatma Mandir Conference Centre

Mahatma Mandir Conference Centre

Gandhinagar (nearest Airport: Ahmedabad), India
Poster P5 Posters

Speaker

Dr Gunyoung Park (National Fusion Research Institute)

Description

Control of the edge localized modes (ELMs) is one of the most critical issues for a ITER and the future tokamak fusion reactors. In order to develop a *predictive* model of the access to ELM-crash suppressed states, it is essential to understand first the underlying physics mechanism of ELM-crash-suppression. This paper reports comparative simulation results for particular KSTAR experimental shot, where both of the ELM mitigated and suppressed phases were observed sequentially and separated distinctly in time with low-n resonant magnetic perturbations (RMPs) in KSTAR. We have observed that toroidal ($\omega_t$) and ExB ($\omega_{ExB}$) rotation frequencies are increased, while electron pressure gradient and the associated electron diamagnetic rotation frequency ($\omega_{*e}$) reduced near the pedestal top through the transition from mitigation to suppression of ELMs. This results in a small outward shift in the zero-crossing of the electron perpendicular rotation ($\omega_{\perp e} \sim 0$) and $\omega_{\perp e}$ becomes even smaller inside the pedestal. Correspondingly, two-fluid linear plasma response modeling with the resistive MHD code M3D-C1 [1] indicates that resonant tearing response is increased significantly near the pedestal top, which is well correlated to the observed onset of ELM-crash suppression. This result is similar to the recent ECEI observation of perpendicular flow changes at the onset of ELM-crash suppression in KSTAR [2]. It remains unclear how the RMP-driven transport (with associated kinetic effects) bring out such changes to the rotation profiles and we plan to study that with XGC0 [3] and XGC1 [4] codes. Detailed results will be presented. References: [1] N. M. Ferraro, Phys. Plasmas **19**, 056105 (2012); [2] J. H. Lee *et al*., APS-DPP (2017); [3] G. Y. Park *et al*., Phys. Plasmas **17**, 102503 (2010); [4] C. S. Chang *et al*., Phys. Plasmas **16**, 056108 (2009)
Country or International Organization Korea, Republic of
Paper Number TH/P5-26

Primary author

Dr Gunyoung Park (National Fusion Research Institute)

Co-authors

Dr Brendan Lyons (General Atomics) Dr Choong-Seock Chang (Princeton Plasma Physics Laboratory and KAIST) Dr Jaehyun Lee (National Fusion Research Institute (NFRI)) Dr Won Ha Ko (National Fusion Research Institute) Dr Yongkyoon In (Ulsan National Institute of Science and Technology (UNIST)) Dr YoungMu Jeon (National Fusion Research Institute)

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Paper