A sustained high-temperature fusion plasma regime facilitated by fast ions

• Published in: Nature (London) Vol. 609; no. 7926; pp. 269 - 275
• Main Authors: Han, H., Park, S. J., Sung, C., Kang, J., Lee, Y. H., Chung, J., Hahm, T. S., Kim, B., Park, J.-K., Bak, J. G., Cha, M. S., Choi, G. J., Choi, M. J., Gwak, J., Hahn, S. H., Jang, J., Lee, K. C., Kim, J. H., Kim, S. K., Kim, W. C., Ko, J., Ko, W. H., Lee, C. Y., Lee, J. H., Lee, J. K., Lee, J. P., Lee, K. D., Park, Y. S., Seo, J., Yang, S. M., Yoon, S. W., Na, Y.-S.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 08.09.2022; Nature Publishing Group
• Subjects: 639/4077/4091/4093; 639/766/1960/1136; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Alternative energy sources; Carbon; Carbon sources; Energy; Fusion reactors; High temperature; Humanities and Social Sciences; Ions; magnetically confined plasmas; multidisciplinary; Nuclear fusion; nuclear fusion and fission; Nuclear reactors; Plasma; Plasma density; Plasma turbulence; Reactors; Science; Science (multidisciplinary); Temperature requirements
• ISSN: 0028-0836; 1476-4687; 1476-4687
• DOI: 10.1038/s41586-022-05008-1

Nuclear fusion is one of the most attractive alternatives to carbon-dependent energy sources 1 . Harnessing energy from nuclear fusion in a large reactor scale, however, still presents many scientific challenges despite the many years of research and steady advances in magnetic confinement approaches. State-of-the-art magnetic fusion devices cannot yet achieve a sustainable fusion performance, which requires a high temperature above 100 million kelvin and sufficient control of instabilities to ensure steady-state operation on the order of tens of seconds 2 , 3 . Here we report experiments at the Korea Superconducting Tokamak Advanced Research 4 device producing a plasma fusion regime that satisfies most of the above requirements: thanks to abundant fast ions stabilizing the core plasma turbulence, we generate plasmas at a temperature of 100 million kelvin lasting up to 20 seconds without plasma edge instabilities or impurity accumulation. A low plasma density combined with a moderate input power for operation is key to establishing this regime by preserving a high fraction of fast ions. This regime is rarely subject to disruption and can be sustained reliably even without a sophisticated control, and thus represents a promising path towards commercial fusion reactors. A magnetic confinement regime established at the Korea Superconducting Tokamak Advanced Research device enables the generation of plasmas over 10 8  kelvin for 20 seconds with the aid of fast ions without plasma edge instabilities or impurity accumulation.