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Recent advances in plasma control and physics research in the Large Helical Device

Tanaka, K. [National Institutes of Natural Sciences, Toki (Japan); Kyushu Univ., Fukuoka (Japan)] (ORCID:0000000216063204)·Ida, K. [National Institutes of Natural Sciences, Toki (Japan)] (ORCID:0000000205854561)·Morishita, Y. [Kyoto Univ. (Japan)]·Ohtani, H. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)] (ORCID:0000000263836425)·Medina Roque, D. [Research Centre for Energy, Environment and Technology (CIEMAT), Madrid (Spain). Laboratorio Nacional de Fusion]·Tokuzawa, T. [National Institutes of Natural Sciences, Toki (Japan); Kyushu Univ., Fukuoka (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)]·Kenmochi, N. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)] (ORCID:0000000310888237)·Kinoshita, T. [Kyushu Univ., Fukuoka (Japan)] (ORCID:0000000339304434)·Toi, K. [National Institutes of Natural Sciences, Toki (Japan)] (ORCID:0000000282448305)·Murakami, S. [Kyoto Univ. (Japan)] (ORCID:0000000225267137)·Funaba, H. [National Institutes of Natural Sciences, Toki (Japan)]·Ichikawa, R. [Kyoto Univ. (Japan)]·Yokoyama, M. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)]·Ueno, G. [The Institute of Statistical Mathematics, Tokyo (Japan)]·Ogawa, K. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)] (ORCID:0000000345551837)·Ohno, N. [University of Hyogo (Japan)]·Kageyama, A. [Kobe Univ. (Japan)]·McCarthy, K.J. [Research Centre for Energy, Environment and Technology (CIEMAT), Madrid (Spain). Laboratorio Nacional de Fusion] (ORCID:0000000258811442)·García-Cortés, I. [Research Centre for Energy, Environment and Technology (CIEMAT), Madrid (Spain). Laboratorio Nacional de Fusion] (ORCID:000000025223391X)·Tamura, N. [Max Planck Institute for Plasma Physics, Greifswald (Germany)] (ORCID:0000000316821519)·Nespoli, F. [Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)] (ORCID:000000017644751X)·Lunsford, R. [Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)] (ORCID:0000000335886801)·Shohji, M. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)] (ORCID:0000000306557347)·Masuzaki, S. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)] (ORCID:0000000301610938)·Suzuki, C. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)] (ORCID:0000000165369034)·Mollen, A. [KTH Royal Inst. of Technology, Stockholm (Sweden)] (ORCID:0000000292577864)·Yoshinuma, M. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)]·Goto, M. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)] (ORCID:000000029160682X)·Kawamoto, Y. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)]·Kawate, T. [Naka Fusion Institute, Ibaraki (Japan)] (ORCID:0000000210210322)·Yamada, I. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)]·Nasu, T. [The Graduate University for Advanced Studies (SOKENDAI)] (ORCID:0000000291727381)·Kobayashi, T. [National Institutes of Natural Sciences, Toki (Japan); Kyushu Univ., Fukuoka (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)] (ORCID:0000000156691937)·Itoh, K. [Chubu University, Aichi (Japan)] (ORCID:0000000338734766)·Mizuno, Y. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)]·Yasuhara, R. [National Institutes of Natural Sciences, Toki (Japan)]·Uehara, H. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)]·DenHartog, D.J. [Univ. of Wisconsin, Madison, WI (United States)]·Takemura, Y. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)] (ORCID:000000033754897X)·Igami, H. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)] (ORCID:0000000245411757)·Yanai, R. [National Institutes of Natural Sciences, Toki (Japan)]·Takeuchi, T. [National Institutes of Natural Sciences, Toki (Japan)] (ORCID:0000000223782610)·Yokoyama, T. [Naka Fusion Institute, Ibaraki (Japan)] (ORCID:0000000227109749)·Osakabe, O. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)] (ORCID:000000015220947X)·Morita, S. [National Institutes of Natural Sciences, Toki (Japan)] (ORCID:0000000341397721)·Shimizu, A. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)] (ORCID:0000000337643184)·Nishiura, M. [National Institutes of Natural Sciences, Toki (Japan); Univ. of Tokyo (Japan)] (ORCID:0000000227523333)·Pablant, N. [Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)] (ORCID:0000000166178459)·Spong, D. A. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000323701873)·Nuga, H. [National Institutes of Natural Sciences, Toki (Japan)] (ORCID:000000033293488X)·Nagaoka, K. [National Institutes of Natural Sciences, Toki (Japan); Nagoya Univ. (Japan)]·Katoh, Y. [Tohoku Univ., Sendai (Japan)] (ORCID:0000000243180633)·Sakamoto, R. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)] (ORCID:000000024453953X)·Yamada, H. [National Institutes of Natural Sciences, Toki (Japan)]
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Abstract

The Large Helical Device (LHD), the largest superconducting helical system in the world, is equipped with advanced heating and diagnostic tools, facilitating plasma control and physics research. Data assimilation was employed for electron temperature control using a real-time Thomson scattering system and real time prediction code. A virtual LHD environment enabled visualization of escaping high-energy tritium ions and demonstrated that these ions impact the rear side of the divertor plate. Pioneering results crucial to plasma control have also been achieved. Real-time wall conditioning using Lithium granule dropping improved bulk ion energy and particle transport while simultaneously enhancing the heavy impurity transport. Progress has also been made in the investigation of turbulence-driven transport. At the confinement bifurcation, ion-scale turbulence decreased, while electron-scale turbulence increased. A change in the anisotropy of turbulent eddies was also observed at the confinement bifurcation. Coexistence of local and non-local turbulence was identified in electron-scale turbulence. Non-local turbulence exhibited the rapid spatial propagation of perturbations throughout the plasma, while local turbulence followed the temperature gradient. A transition between drift-wave turbulence and magnetohydrodynamics (MHD) turbulence was observed with the turbulence minimized at the transition condition. Machine learning analysis was employed to evaluate the temperate and density conditions of this turbulence transition. Then, real-time control of fueling and heating was applied to maintain the turbulence transition condition, improving the energy confinement enhancement factor by 20%. In addition, evidence was obtained for collisionless ion heating by energetic-ion-driven geodesic acoustic modes and MHD bursts. These achievements represent unique contributions to the development of fusion reactors.

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Tanaka, K. [National Institutes of Natural Sciences, Toki (Japan); Kyushu Univ., Fukuoka (Japan)] (ORCID:0000000216063204), Ida, K. [National Institutes of Natural Sciences, Toki (Japan)] (ORCID:0000000205854561), Morishita, Y. [Kyoto Univ. (Japan)], Ohtani, H. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)] (ORCID:0000000263836425), Medina Roque, D. [Research Centre for Energy, Environment and Technology (CIEMAT), Madrid (Spain). Laboratorio Nacional de Fusion], Tokuzawa, T. [National Institutes of Natural Sciences, Toki (Japan); Kyushu Univ., Fukuoka (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)], Kenmochi, N. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)] (ORCID:0000000310888237), Kinoshita, T. [Kyushu Univ., Fukuoka (Japan)] (ORCID:0000000339304434), Toi, K. [National Institutes of Natural Sciences, Toki (Japan)] (ORCID:0000000282448305), Murakami, S. [Kyoto Univ. (Japan)] (ORCID:0000000225267137), Funaba, H. [National Institutes of Natural Sciences, Toki (Japan)], Ichikawa, R. [Kyoto Univ. (Japan)], Yokoyama, M. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)], Ueno, G. [The Institute of Statistical Mathematics, Tokyo (Japan)], Ogawa, K. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)] (ORCID:0000000345551837), Ohno, N. [University of Hyogo (Japan)], Kageyama, A. [Kobe Univ. (Japan)], McCarthy, K.J. [Research Centre for Energy, Environment and Technology (CIEMAT), Madrid (Spain). Laboratorio Nacional de Fusion] (ORCID:0000000258811442), García-Cortés, I. [Research Centre for Energy, Environment and Technology (CIEMAT), Madrid (Spain). Laboratorio Nacional de Fusion] (ORCID:000000025223391X), Tamura, N. [Max Planck Institute for Plasma Physics, Greifswald (Germany)] (ORCID:0000000316821519), Nespoli, F. [Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)] (ORCID:000000017644751X), Lunsford, R. [Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)] (ORCID:0000000335886801), Shohji, M. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)] (ORCID:0000000306557347), Masuzaki, S. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)] (ORCID:0000000301610938), Suzuki, C. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)] (ORCID:0000000165369034), Mollen, A. [KTH Royal Inst. of Technology, Stockholm (Sweden)] (ORCID:0000000292577864), Yoshinuma, M. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)], Goto, M. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)] (ORCID:000000029160682X), Kawamoto, Y. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)], Kawate, T. [Naka Fusion Institute, Ibaraki (Japan)] (ORCID:0000000210210322), Yamada, I. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)], Nasu, T. [The Graduate University for Advanced Studies (SOKENDAI)] (ORCID:0000000291727381), Kobayashi, T. [National Institutes of Natural Sciences, Toki (Japan); Kyushu Univ., Fukuoka (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)] (ORCID:0000000156691937), Itoh, K. [Chubu University, Aichi (Japan)] (ORCID:0000000338734766), Mizuno, Y. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)], Yasuhara, R. [National Institutes of Natural Sciences, Toki (Japan)], Uehara, H. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)], DenHartog, D.J. [Univ. of Wisconsin, Madison, WI (United States)], Takemura, Y. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)] (ORCID:000000033754897X), Igami, H. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)] (ORCID:0000000245411757), Yanai, R. [National Institutes of Natural Sciences, Toki (Japan)], Takeuchi, T. [National Institutes of Natural Sciences, Toki (Japan)] (ORCID:0000000223782610), Yokoyama, T. [Naka Fusion Institute, Ibaraki (Japan)] (ORCID:0000000227109749), Osakabe, O. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)] (ORCID:000000015220947X), Morita, S. [National Institutes of Natural Sciences, Toki (Japan)] (ORCID:0000000341397721), Shimizu, A. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)] (ORCID:0000000337643184), Nishiura, M. [National Institutes of Natural Sciences, Toki (Japan); Univ. of Tokyo (Japan)] (ORCID:0000000227523333), Pablant, N. [Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)] (ORCID:0000000166178459), Spong, D. A. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000323701873), Nuga, H. [National Institutes of Natural Sciences, Toki (Japan)] (ORCID:000000033293488X), Nagaoka, K. [National Institutes of Natural Sciences, Toki (Japan); Nagoya Univ. (Japan)], Katoh, Y. [Tohoku Univ., Sendai (Japan)] (ORCID:0000000243180633), Sakamoto, R. [National Institutes of Natural Sciences, Toki (Japan); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)] (ORCID:000000024453953X), Yamada, H. [National Institutes of Natural Sciences, Toki (Japan)]. 2026-06-29. Recent advances in plasma control and physics research in the Large Helical Device. https://doi.org/10.1088/1741-4326%2Fae71eb

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