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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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.
The authors declare no competing financial interests.
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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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