Demonstration of reduced neoclassical energy transport in Wendelstein 7-X
<jats:title>Abstract</jats:title><jats:p>Research on magnetic confinement of high-temperature plasmas has the ultimate goal of harnessing nuclear fusion for the production of electricity. Although the tokamak<jats:sup>1</jats:sup> is the leading toroidal magnetic-confin...
| Main Authors: | , |
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| Other Authors: | |
| Format: | Article |
| Language: | English |
| Published: |
Springer Science and Business Media LLC
2023
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| Online Access: | https://hdl.handle.net/1721.1/147630 |
| _version_ | 1826190799736406016 |
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| author | White, Anne Porkolab, Miklos |
| author2 | Massachusetts Institute of Technology. Department of Nuclear Science and Engineering |
| author_facet | Massachusetts Institute of Technology. Department of Nuclear Science and Engineering White, Anne Porkolab, Miklos |
| author_sort | White, Anne |
| collection | MIT |
| description | <jats:title>Abstract</jats:title><jats:p>Research on magnetic confinement of high-temperature plasmas has the ultimate goal of harnessing nuclear fusion for the production of electricity. Although the tokamak<jats:sup>1</jats:sup> is the leading toroidal magnetic-confinement concept, it is not without shortcomings and the fusion community has therefore also pursued alternative concepts such as the stellarator. Unlike axisymmetric tokamaks, stellarators possess a three-dimensional (3D) magnetic field geometry. The availability of this additional dimension opens up an extensive configuration space for computational optimization of both the field geometry itself and the current-carrying coils that produce it. Such an optimization was undertaken in designing Wendelstein 7-X (W7-X)<jats:sup>2</jats:sup>, a large helical-axis advanced stellarator (HELIAS), which began operation in 2015 at Greifswald, Germany. A major drawback of 3D magnetic field geometry, however, is that it introduces a strong temperature dependence into the stellarator’s non-turbulent ‘neoclassical’ energy transport. Indeed, such energy losses will become prohibitive in high-temperature reactor plasmas unless a strong reduction of the geometrical factor associated with this transport can be achieved; such a reduction was therefore a principal goal of the design of W7-X. In spite of the modest heating power currently available, W7-X has already been able to achieve high-temperature plasma conditions during its 2017 and 2018 experimental campaigns, producing record values of the fusion triple product for such stellarator plasmas<jats:sup>3,4</jats:sup>. The triple product of plasma density, ion temperature and energy confinement time is used in fusion research as a figure of merit, as it must attain a certain threshold value before net-energy-producing operation of a reactor becomes possible<jats:sup>1,5</jats:sup>. Here we demonstrate that such record values provide evidence for reduced neoclassical energy transport in W7-X, as the plasma profiles that produced these results could not have been obtained in stellarators lacking a comparably high level of neoclassical optimization.</jats:p> |
| first_indexed | 2024-09-23T08:45:32Z |
| format | Article |
| id | mit-1721.1/147630 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T08:45:32Z |
| publishDate | 2023 |
| publisher | Springer Science and Business Media LLC |
| record_format | dspace |
| spelling | mit-1721.1/1476302023-01-24T03:47:14Z Demonstration of reduced neoclassical energy transport in Wendelstein 7-X White, Anne Porkolab, Miklos Massachusetts Institute of Technology. Department of Nuclear Science and Engineering Massachusetts Institute of Technology. Department of Physics <jats:title>Abstract</jats:title><jats:p>Research on magnetic confinement of high-temperature plasmas has the ultimate goal of harnessing nuclear fusion for the production of electricity. Although the tokamak<jats:sup>1</jats:sup> is the leading toroidal magnetic-confinement concept, it is not without shortcomings and the fusion community has therefore also pursued alternative concepts such as the stellarator. Unlike axisymmetric tokamaks, stellarators possess a three-dimensional (3D) magnetic field geometry. The availability of this additional dimension opens up an extensive configuration space for computational optimization of both the field geometry itself and the current-carrying coils that produce it. Such an optimization was undertaken in designing Wendelstein 7-X (W7-X)<jats:sup>2</jats:sup>, a large helical-axis advanced stellarator (HELIAS), which began operation in 2015 at Greifswald, Germany. A major drawback of 3D magnetic field geometry, however, is that it introduces a strong temperature dependence into the stellarator’s non-turbulent ‘neoclassical’ energy transport. Indeed, such energy losses will become prohibitive in high-temperature reactor plasmas unless a strong reduction of the geometrical factor associated with this transport can be achieved; such a reduction was therefore a principal goal of the design of W7-X. In spite of the modest heating power currently available, W7-X has already been able to achieve high-temperature plasma conditions during its 2017 and 2018 experimental campaigns, producing record values of the fusion triple product for such stellarator plasmas<jats:sup>3,4</jats:sup>. The triple product of plasma density, ion temperature and energy confinement time is used in fusion research as a figure of merit, as it must attain a certain threshold value before net-energy-producing operation of a reactor becomes possible<jats:sup>1,5</jats:sup>. Here we demonstrate that such record values provide evidence for reduced neoclassical energy transport in W7-X, as the plasma profiles that produced these results could not have been obtained in stellarators lacking a comparably high level of neoclassical optimization.</jats:p> 2023-01-23T14:46:51Z 2023-01-23T14:46:51Z 2021 2023-01-23T13:58:50Z Article http://purl.org/eprint/type/JournalArticle https://hdl.handle.net/1721.1/147630 White, Anne and Porkolab, Miklos. 2021. "Demonstration of reduced neoclassical energy transport in Wendelstein 7-X." Nature, 596 (7871). en 10.1038/S41586-021-03687-W Nature Creative Commons Attribution 4.0 International license https://creativecommons.org/licenses/by/4.0/ application/pdf Springer Science and Business Media LLC Nature |
| spellingShingle | White, Anne Porkolab, Miklos Demonstration of reduced neoclassical energy transport in Wendelstein 7-X |
| title | Demonstration of reduced neoclassical energy transport in Wendelstein 7-X |
| title_full | Demonstration of reduced neoclassical energy transport in Wendelstein 7-X |
| title_fullStr | Demonstration of reduced neoclassical energy transport in Wendelstein 7-X |
| title_full_unstemmed | Demonstration of reduced neoclassical energy transport in Wendelstein 7-X |
| title_short | Demonstration of reduced neoclassical energy transport in Wendelstein 7-X |
| title_sort | demonstration of reduced neoclassical energy transport in wendelstein 7 x |
| url | https://hdl.handle.net/1721.1/147630 |
| work_keys_str_mv | AT whiteanne demonstrationofreducedneoclassicalenergytransportinwendelstein7x AT porkolabmiklos demonstrationofreducedneoclassicalenergytransportinwendelstein7x |