Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2023 Jan 6;9(1):eabq5273.
doi: 10.1126/sciadv.abq5273. Epub 2023 Jan 6.

Realization of thousand-second improved confinement plasma with Super I-mode in Tokamak EAST

Yuntao Song  1 , Xiaolan Zou  2 , Xianzu Gong  1 , Alain Becoulet  2 , Richard Buttery  3 , Paul Bonoli  4 , Tuong Hoang  1 , Rajesh Maingi  5 , Jinping Qian  1 , Xiaoming Zhong  6 , Adi Liu  6 , Erzhong Li  1 , Rui Ding  1 , Juan Huang  1 , Qing Zang  1 , Haiqing Liu  1 , Liang Wang  1 , Ling Zhang  1 , Guoqiang Li  1 , Youwen Sun  1 , Andrea Garofalo  3 , Tom Osborne  3 , Tony Leonard  3 , Seung Gyou Baek  4 , Greg Wallace  4 , Liqing Xu  1 , Bin Zhang  1 , Shouxin Wang  1 , Yuqi Chu  1 , Tao Zhang  1 , Yanmin Duan  1 , Hui Lian  1 , Xuexi Zhang  1 , Yifei Jin  1 , Long Zeng  1 , Bo Lyu  1 , Binjia Xiao  1 , Yao Huang  1 , Yong Wang  1 , Biao Shen  1 , Nong Xiang  1 , Yu Wu  1 , Jiefeng Wu  1 , Xiaojie Wang  1 , Bojiang Ding  1 , Miaohui Li  1 , Xinjun Zhang  1 , Chengming Qin  1 , Weibin Xi  1 , Jian Zhang  1 , Liansheng Huang  1 , Damao Yao  1 , Yanlan Hu  1 , Guizhong Zuo  1 , Qiping Yuan  1 , Zhiwei Zhou  1 , Mao Wang  1 , Handong Xu  1 , Yahong Xie  1 , Zhengchu Wang  1 , Junling Chen  1 , Guosheng Xu  1 , Jiansheng Hu  1 , Kun Lu  1 , Fukun Liu  1 , Xinchao Wu  1 , Baonian Wan  1 , Jiangang Li  1 ; EAST Team
Affiliations

Realization of thousand-second improved confinement plasma with Super I-mode in Tokamak EAST

Yuntao Song et al. Sci Adv. .

Abstract

Mastering nuclear fusion, which is an abundant, safe, and environmentally competitive energy, is a great challenge for humanity. Tokamak represents one of the most promising paths toward controlled fusion. Obtaining a high-performance, steady-state, and long-pulse plasma regime remains a critical issue. Recently, a big breakthrough in steady-state operation was made on the Experimental Advanced Superconducting Tokamak (EAST). A steady-state plasma with a world-record pulse length of 1056 s was obtained, where the density and the divertor peak heat flux were well controlled, with no core impurity accumulation, and a new high-confinement and self-organizing regime (Super I-mode = I-mode + e-ITB) was discovered and demonstrated. These achievements contribute to the integration of fusion plasma technology and physics, which is essential to operate next-step devices.

PubMed Disclaimer

Figures

Fig. 1.
Fig. 1.. Waveform of the thousand-second discharge #106915.
(A) Plasma current Ip and line-averaged electron density n¯e. (B) LHCD, ECRH, and radiated powers. (C) Contour of particle flux given by the ion saturation current js on the divertor target, with the strike points calculated from EFIT equilibrium shown in open circles (SP1 and SP2 are outer strike points for two X-points in double-null configuration, respectively). (D) Peak heat flux on the divertor target.
Fig. 2.
Fig. 2.. LHCD efficiency.
Experimental comparison of LHCD efficiency in the L-mode, H-mode, and Super I-mode.
Fig. 3.
Fig. 3.. Pumping rate and global recycling.
(A) Gas injection rate of supersonic molecular beam injection (SMBI) and gas puffing. (B) Pumping rate of divertor cryopumps and the first wall. (C) Global recycling coefficient.
Fig. 4.
Fig. 4.. Tungsten (W) impurity radiation.
Line intensity profiles of W ions in discharge #106915, compared with discharge operated in H-mode (#106928: Ip = 400 kA, 2 MW of LHCD, 1 MW of ECRH). (A) W29+, (B) W32+, (C) W43+, and (D) W45+ ions observed by space-resolved EUV spectrometers (vertical dashed lines indicate peak position of line intensities in H-mode).
Fig. 5.
Fig. 5.. I-mode identification.
(A) Energy confinement enhancement factor H98 and the normalized plasma pressure βp. (B) Electron temperature Te measured at ρ = 0.03 by electron cyclotron emission (ECE) diagnostic. Note that the central ECE measurement is less affected by the suprathermal electrons generated by LHCD and is also calibrated with Thomson scattering. (C) Frequency spectrogram of the time derivative of the density fluctuation phase dϕ/dt measured using a Doppler reflectometer at ρ = 0.91, showing WCM (30 to 100 kHz) and ETRO (14 kHz). (D) Amplitude of WCM. a.u., arbitrary units.
Fig. 6.
Fig. 6.. Electron temperature and density profiles for transport analysis.
The temperature and density radial profiles of Super I-mode (discharge #106915, in red) are compared to those of the H-mode (discharge #107832, in green) and L-mode (discharge #106870, in blue). (A) Electron temperature profiles from the Thomson scattering diagnostic, showing evident ITB for Super I-mode and H-mode. (B) Electron density profile from the reflectometer. (C) Zoomed view of the electron temperature profile at the edge for better differentiating the pedestal of Super I-mode from L-mode. (D) Zoomed view of the electron density profile at the edge, showing similar edge density profile for Super I-mode and L-mode. (E) Electron thermal conductivity in discharge #106915, deduced from the power balance analysis.
Fig. 7.
Fig. 7.. Interaction between MHD, turbulence, and electron heat transport for sustaining stationary ITB.
(A) Safety factor q reconstructed using a polarimeter-interferometer (POINT) system; q95 is 9.3. (B) MHD frequency spectrum measured in the plasma core using SXR diagnostic; the MHD frequency is in the range of 4 to 8 kHz. (C) Magnified view of MHD intensity at t = 17.8 to 19 s. (D) Normalized electron temperature gradient R/LTe at t = 17.8 to 19 s. (E) Turbulence frequency spectrogram and intensity at t = 17.8 to 19 s.
Fig. 8.
Fig. 8.. Comparison of the energy confinement enhancement factor H98 and the plasma duration.
Various plasma regimes obtained in EAST are compared: Super I-mode (solid red square), standard I-mode (red square), H-mode (blue triangle), L-mode with ITB (violet circle), and L-mode without ITB (black diamond).
Fig. 9.
Fig. 9.. Diagram of fusion triple-product [ni(0)Ti(0)τE] versus plasma duration t(s) for mega-ampere and megawatt class tokamaks.
Data of JT-60, JET, and Tore Supra are taken from table 3.1 in (37).
See this image and copyright information in PMC

References

    1. M. G. Bell, K. M. McGuire, V. Arunasalam, C. W. Barnes, S. H. Batha, G. Bateman, M. A. Beer, R. E. Bell, M. Bitter, N. L. Bretz, R. V. Budny, C. E. Bush, S. R. Cauffman, Z. Chang, C.-S. Chang, C. Z. Cheng, D. S. Darrow, R. O. Dendy, W. Dorland, H. H. Duong, R. D. Durst, P. C. Efthimion, D. Ernst, H. Evenson, N. J. Fisch, R. K. Fisher, R. J. Fonck, E. D. Fredrickson, G. Y. Fu, H. P. Furth, N. N. Gorelenkov, B. Grek, L. R. Grisham, G. W. Hammett, G. R. Hanson, R. J. Hawryluk, W. W. Heidbrink, H. W. Herrmann, K. W. Hill, J. C. Hosea, H. Hsuan, M. H. Hughes, R. A. Hulse, A. C. Janos, D. L. Jassby, F. C. Jobes, D. W. Johnson, L. C. Johnson, J. Kesner, H. W. Kugel, N. T. Lam, B. Leblanc, F. M. Levinton, J. Machuzak, R. Majeski, D. K. Mansfield, E. Mazzucato, M. E. Mauel, J. M. McChesney, D. C. McCune, G. McKee, D. M. Meade, S. S. Medley, D. R. Mikkelsen, S. V. Mirnov, D. Mueller, G. A. Navratil, R. Nazikian, D. K. Owens, H. K. Park, W. Park, P. B. Parks, S. F. Paul, M. P. Petrov, C. K. Phillips, M. W. Phillips, C. S. Pitcher, A. T. Ramsey, M. H. Redi, G. Rewoldt, D. R. Roberts, J. H. Rogers, E. Ruskov, S. A. Sabbagh, M. Sasao, G. Schilling, J. F. Schivell, G. L. Schmidt, S. D. Scott, I. Semenov, S. Sesnic, C. H. Skinner, B. C. Stratton, J. D. Strachan, W. Stodiek, E. J. Synakowski, H. Takahashi, W. M. Tang, G. Taylor, J. L. Terry, M. E. Thompson, W. Tighe, S. V. Goeler, R. B. White, R. M. Wieland, J. R. Wilson, K.-L. Wong, P. Woskov, G. A. Wurden, M. Yamada, K. M. Young, M. C. Zarnstorff, S. J. Zweben, Overview of DT results from TFTR. Nucl. Fusion 35, 1429–1436 (1995).
    1. J. Jacquinot, V. P. Bhatnagar, J. G. Cordey, L. D. Horton, D. F. H. Start, R. Barnsley, P. Breger, J. P. Christiansen, S. Clement, S. J. Davies, J. K. Ehrenberg, L.-G. Eriksson, G. M. Fishpool, M. Gadeberg, P. J. Harbour, H. J. Jäckel, K. Lawson, J. Lingertat, C. G. Lowry, C. F. Maggi, G. F. Matthews, R. D. Monk, D. P. O’Brien, E. Righi, G. Saibene, R. Sartori, B. Schunke, A. C. C. Sips, M. F. Stamp, D. Stork, J. D. Strachan, A. Tanga, K. Thomsen; JET Team , Overview of ITER physics deuterium-tritium experiments in JET. Nucl. Fusion 39, 235–253 (1999).
    1. J. Li, H. Y. Guo, B. N. Wan, X. Z. Gong, Y. F. Liang, G. S. Xu, K. F. Gan, J. S. Hu, H. Q. Wang, L. Wang, L. Zeng, Y. P. Zhao, P. Denner, G. L. Jackson, A. Loarte, R. Maingi, J. E. Menard, M. Rack, X. L. Zou, A long-pulse high-confinement plasma regime in the Experimental Advanced Superconducting Tokamak. Nat. Phys. 9, 817–821 (2013).
    1. ITER, http://www.iter.org/.
    1. Y. Wan, J. Li, Y. Liu, X. Wang, V. Chan, C. Chen, X. Duan, P. Fu, X. Gao, K. Feng, S. Liu, Y. Song, P. Weng, B. Wan, F. Wan, H. Wang, S. Wu, M. Ye, Q. Yang, G. Zheng, G. Zhuang, Q. Li, Overview of the present progress and activities on the CFETR. Nucl. Fusion 57, 102009 (2017).