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10-15 May 2021
Virtual Event
Europe/Vienna timezone
The Conference will be held virtually from 10-15 May 2021

EAST Steady-state Long Pulse H-mode with Core-edge Integration for CFETR

11 May 2021, 09:38
17m
Virtual Event

Virtual Event

Regular Oral Magnetic Fusion Experiments EX/1-TH/1 H & CD & Steady-state & Operation

Speaker

Xianzu Gong (Insititute of Plasma Physics, Chinese Academy Sciences)

Description

Recent EAST experiment has successfully demonstrated long pulse steady-state high plasma performance scenario with core-edge integration since the last IAEA in 2018 $[1]$. A discharge with a duration over 60s with $\beta_P$ ~2.0, $\beta_N$ ~1.6, $H_{98y2}$~1.3 and internal transport barrier on electron temperature channel is obtained with multi-RF power heating and current drive, i.e. ~2.5 MW LHW and 0.9 MW ECH, where the plasma configuration is the upper single null with the strike points on the tungsten divertor (shown in figure 1). Loop voltage was well controlled to be zero which indicates the fully non-inductive current drive condition. Small ELMs (frequency ~100-200Hz) were obtained in this long pulse H-mode discharge. In the operation, the optimization of X-point, the outer gap and local gas puffing near LHW antenna were investigated to maintain RF power coupling and to avoid formation of hot spot on the 4.6 GHz LHW antenna. Global parameters of toroidal field $B_T$ and line averaged electron density <$n_e$> were optimized for high current drive efficiency of LHW and for on-axis deposition of ECH. The on-axis ECH was applied not only for the core electron heating, but also for the control of high $Z_{eff}$ impurities in the core plasmas.

Time histories of several parameters for EAST 60s high $\beta_P$ long pulse discharge.

Meanwhile, a higher $\beta_N$ ~1.8 with a duration of 20s is achieved by using the modulated neutral beam. Several normalized parameters of $\beta_P$ ($\beta_P$ ~2.0), $\beta_N$ ($\beta_N$ ~1.8), $H_{98y2}$ (~1.3), $n_e/n_{GW}$ (~ 0.75) are close or even higher than the phase III 1GW scenario of CFETR steady-state $[2]$. Other features such as metal wall (tungsten divertor), low torque injection ($\Gamma_{inj}$~1.0Nm), electron dominated heating ($T_e$>$T_i$), moderate bootstrap current fraction ($f_{bs}$~50%), broaden current density profile with the central q(0)>1.0 and good energy confinement, have also been demonstrated in this scenario. Note that high-Z impurity accumulation in the plasma core was well controlled in a low level by using the on-axis ECH and reducing the fast ion losses through beam energy optimization.

EAST high $\beta_P$ discharge with core-edge integration.

More recently, EAST has demonstrated a compatible core and edge integration in high $\beta_P$ scenarios: high confinement $H_{98y2}$>1.2 with high $\beta_P$ ~2.5/$\beta_N$~2.0, $f_{bs}$~50% is sustained with reduced heat flux by active divertor heat flux at high density $n_e/n_{GW}$ ~0.7 and moderate $q_{95}$~6.7 (shown in figure 2). The energy confinement quality was almost maintained with $H_{98y2}$>1.2 during the radiation feedback control. By active impurity seeding through radiative divertor feedback control via radiated power, the peak heat flux is reduced by ~30% on the ITER-like tungsten divertor, here a mixture of 50% neon and 50% $D_2$ is applied. Note that EAST has developed a number of heat flux control techniques to reduce heat load in separate experiments.

In summary, recent EAST experiments demonstrated long pulse steady-state high plasma performance scenarios and heat flux feedback control. Detailed physics basis to investigate stability and particle transport will be presented for the understanding of fully integrated core-edge solutions on EAST. As a test bed for ITER and CFETR, the EAST upcoming experiments will further exploit additional heating power and demonstrate the core-edge integration of steady-state long pulse high performance scenarios with full metal walls.

This work was supported in part by National Natural Science Foundation of China under Grant No. 11975274,11975276, US Department of Energy under DE-SC0010685 and DE-FC02-04ER54698.

$[1]$ X. Gong et al 2019 Nucl. Fusion 59 086030
$[2]$ J. Huang et al 2020 Plasma Phys. Control. Fusion 62 014019

Country or International Organization China
Affiliation Institute of Plasma Physics, Chinese Academy of Sciences

Primary author

Xianzu Gong (Insititute of Plasma Physics, Chinese Academy Sciences)

Co-authors

A. M. Garofalo (General Atomics) Juan Huang (CnIPPCAS) Jinping Qian (Institute of plasma physics, Chinese academy of sciences) Annika Ekedahl (CEA, IRFM) Rajesh Maingi (Princeton Plasma Physics Laboratory) Fukun Liu (Institute of Plasma Physics, CAS) Yanping Zhao (Institute of Plasma Physics, CAS) Prof. Bingjia Xiao (Institute of Plasma Physics, Chinese Academy of Sciences) Jiansheng Hu (Institute of Plasma Physics, Chinese Academy of Sciences) Chundong Hu (Institute of Plasma Physics, CAS) Liqun Hu (Institute of Plasma Physcis, Chinese Academy of Sciences) Mao Wang (Institute of Plasma Physics, CAS) Handong Xu (Institute of Plasma Physics, CAS) Erzhong Li (Institute of Plasma Physics, CAS) Dr Long Zeng Dr Qing Zang (institute of plasma physics, Chinese academy of sciences) Dr Haiqing Liu (Institute of plasma physics, Chinese academy of sciences) Bo Lyu (Institute of Plasma Physics, Chinese Academy of Sciences) Ms Qiping Yuan (Institute of Plasma Physics, Chinese Academy of Sciences) Mr Kedong Li (Institute of Plasma Physics, Chinese Academy of Sciences) Dr Bin Zhang (Institute of Plasma Physics, Chinese Academy of Sciences) Xiang Gu (Institute of Plasma Physics, CAS) Jiayuan Zhang (Institute of Plasma Physics, CAS) Tianqi Jia (Institute of Plasma Physics, CAS) Mr Muquan Wu (Institute of Plasma Physics, Chinese Academy of Sciences) Jiale Chen Dr Xiang Zhu (Shenzhen University) Miaohui Li (Institute of Plasma Physics,Chinese Academy of Sciences (ASIPP)) Xinjun Zhang (Institute of Plasma Physics Chinese Academy of Sciences (ASIPP)) Ling Zhang (Institute of Plasma Physics, Chinese Academy of Sciences) Dr Yanmin Duan (Institute of Plasma Physics, Chinese Academy of Sciences) Liang Wang (Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP)) Rui Ding (Institute of Plasma Physics, Chinese Academy of Sciences) Youwen Sun (Institute of Plasma Physics, Chinese Academy of Scienses) Guosheng Xu (Institute of Plasma Physics, Chinese Academy of Sciences) Yunfeng Liang (Forschungszentrum Jülich GmbH, Germany) Nong Xiang (Institute of plasma physics, Chinese academy of science) Baonian Wan (Institute of Plasma Physics, Chinese Academy of Sciences) Jiangang Li (Institute of Plasma Physics, Chinese Academy of Sciences) the EAST Team

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