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A long-pulse high-confinement plasma regime in the Experimental Advanced Superconducting Tokamak

Nature Physics volume 9, pages 817–821 (2013)Cite this article

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Abstract

High-performance and long-pulse operation is a crucial goal of current magnetic fusion research. Here, we demonstrate a high-confinement plasma regime known as an H-mode with a record pulse length of over 30 s in the Experimental Advanced Superconducting Tokamak sustained by lower hybrid wave current drive (LHCD) with advanced lithium wall conditioning. We find that LHCD provides a flexible boundary control for a ubiquitous edge instability in H-mode plasmas known as an edge-localized mode, which leads to a marked reduction in the heat load on the vessel wall compared with standard edge-localized modes. LHCD also induces edge plasma ergodization that broadens the heat deposition footprint. The heat transport caused by this ergodization can be actively controlled by regulating the edge plasma conditions. This potentially offers a new means for heat-flux control, which is a key issue for next-step fusion development.

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Figure 1: Internal view of EAST.
Figure 2: Demonstration of a high-confinement H-mode discharge over 30 s driven by LHCD with ICRH.
Figure 3: Demonstration of the effect of LHCD on ELM behaviour by modulating LCHD power in a series of target H-mode plasmas produced by ICRH with different edge safety factor, q95.
Figure 4: Contour plot of the magnetic perturbation spectrum with different q95.
Figure 5: Edge plasma conditions significantly influence the degree of the SHF induced by LHCD.

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Acknowledgements

We would like to acknowledge the support and contributions from the rest of the EAST team and collaborators. This work was supported in part by the National Nature Science Foundation of China under Contract No. 11021565 and the National Magnetic Confinement Fusion Science Program of China under Contract Nos. 2010GB104001, 2010GB104002, 2011GB101000, 2011GB107001, 2012GB101001, 2013GB107003 and 2013GB106003, as well as the Thousand Talent Plan of China and Helmholtz Association in the frame of the Helmholtz-University Young Investigators Group VH-NG-410. The views and opinions expressed herein do not necessarily reflect those of the ITER Organization.

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Authors and Affiliations

  1. Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China

    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

  2. Tri Alpha Energy, Inc., PO Box 7010, Rancho Santa Margarita, California 92688, USA

    H. Y. Guo

  3. Forschungszentrum Jülich GmbH, Association EURATOM-FZ Jülich, Institut für Energie- und Klimaforschung-Plasmaphysik, Trilateral Euregio Cluster D-52425 Jülich, Germany

    Y. F. Liang, P. Denner & M. Rack

  4. General Atomics, PO Box 85608, San Diego, California 92186, USA

    G. L. Jackson

  5. ITER Organization, Route de Vinon sur Verdon, 13115 St Paul Lez Durance, France

    A. Loarte

  6. Princeton Plasma Physics Laboratory, PO Box 451, Princeton, New Jersey 08543, USA

    R. Maingi & J. E. Menard

  7. Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA

    R. Maingi

  8. CEA, IRFM, F-13108 Saint-Paul-lez-Durance, France

    X. L. Zou

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  1. J. Li
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Correspondence to H. Y. Guo.

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Li, J., Guo, H., Wan, B. et al. A long-pulse high-confinement plasma regime in the Experimental Advanced Superconducting Tokamak. Nature Phys 9, 817–821 (2013). https://doi.org/10.1038/nphys2795

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