7th Asia-Pacific Conference on Plasma Physics, 12-17 Nov, 2023 at Port Messe Nagoya

Nonlinear transition of divertor heat fluxes distribution during n=4 RMP
suppressed ELM in EAST

Hua Yang1,2, Youwen Sun1,*, Manni Jia1,*, Alberto Loarte3, Cheng Ye1,2, Qun Ma1,2, PengchengXie1,2, Xuemin Wu1,2, Ruirong Liang1,2, Bin Zhang1, Qing Zang1, Tao Zhang1 and EAST
Contributors
1
Institute of Plasma Physics, Hefei Institutues of Physical Science, Chinese Academy of Sciences,Hefei 230031, China,
2
University of Science and Technology of China, Hefei 230026, China3ITER Organization, Route de Vinon sur Verdon, 13115 St Paul Lez Durance, Francee-mail (speaker): hua.yang1@ipp.ac.cn
Nonlinear transition of stationary heat fluxes deposition
on original and splitting strike lines on the divertor target
during transition of type-I edge localized mode (ELM)
mitigation to suppression using n=4 RMP has been
observed, as shown in figure1. The peak temperature
value on the divertor heat flux profile is changed fromthe original strike line to the splitting strike line during
this process. The nonlinear transition of ELM mitigation
to suppression with n=1 RMP has been proved withmagnetic diagnose plasma response [1]. The observation
provides a new perspective to understand the key physics
in achieving ELM suppression.
Simulation of divertor magnetic footprints using
magnetic field lines tracing code TOP2D has shown
similar patterns with plasma response calculated bylinear fluid code MARS-F [2]. However, to gain a further
understanding, EMC3-EIRENE combined with aquasi-linear code MARS-Q are used to study theinfluence of nonlinear plasma response effects on theedge plasma transport in the EAST standard
configuration. The modeling results show a similar
time-dependent evolution as the divertor temperatureobserved by the infra-red camera system. These results
indicate that RMP penetration into deeper plasma region
may play an important role in achieving ELM
suppression, with the edge magnetic topology playing akey role in reforming the edge plasma profiles andresulting in the non-linear transition of divertor heat
fluxes deposition between original and splitting strikelines. Previous modeling with EMC3-Eirene for ITER
shows that the heat load onto the splitting strike lines
could be still significant although detachment has beenachieved on the original strike lines with gas puffing
during RMP application [3]. Thus, understanding thenon-linear transition of divertor heat flux splitting andthe physical mechanism of this process is important for
the further exploration of optimizing the divertor power
exhaust scheme, such as the integration of RMP ELM

suppression and gas puffing or impurity seeding for
future ITER application.
This work is supported by the National Key R&D
Program of China under Grant No. 2017YFE0301100,
the National Natural Science Foundation of China underGrant Nos. 12005261 and 11875292 and the Science
Foundation of Institute of Plasma Physics, Chinese
Academy of Sciences No. DSJJ-2020-05.

References[1] Y. Sun, et al PRL 117, 115001 (2016)[2] Manni Jia, et al Nucl. Fusion 61 106023 (2021)[3] H. Frerichs, et al PRL 125, 155001 (2020)
Figure 1 The time evolution of plasma parameters anddivertor surface temperature

Figure 1. Time trace of EAST #93527