Benign saturation of ideal ballooning instability in a high-performance stellarator
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arXiv
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| Hauptverfasser: | , , , |
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| Format: | Preprint |
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2024
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| _version_ | 1866914959415312384 |
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| author | Zhou, Yao Aleynikova, K. Liu, Chang Ferraro, N. M. |
| author_facet | Zhou, Yao Aleynikova, K. Liu, Chang Ferraro, N. M. |
| contents | To examine the robustness of the designed 5% $β$-limit for high-performance operation in the W7-X stellarator, we undertake nonlinear magnetohydrodynamic (MHD) simulations of pressure-driven instabilities using the M3D-$C^1$ code. Consistent with linear analyses, ideal ballooning instabilities occur as $β$ exceeds 5% in the standard configuration. Nonetheless, the modes saturate nonlinearly at relatively low levels without triggering large-scale crashes, even though confinement degradation worsens as $β$ increases. In contrast, in an alternative configuration with nearly zero magnetic shear, ideal interchange modes induce a pressure crash at $β= 1\%$. These results suggest that the standard W7-X configuration might have a soft $β$-limit that is fairly immune to major MHD events, which enhances the appeal of the stellarator approach to steady-state fusion reactors. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2404_01966 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Benign saturation of ideal ballooning instability in a high-performance stellarator Zhou, Yao Aleynikova, K. Liu, Chang Ferraro, N. M. Plasma Physics To examine the robustness of the designed 5% $β$-limit for high-performance operation in the W7-X stellarator, we undertake nonlinear magnetohydrodynamic (MHD) simulations of pressure-driven instabilities using the M3D-$C^1$ code. Consistent with linear analyses, ideal ballooning instabilities occur as $β$ exceeds 5% in the standard configuration. Nonetheless, the modes saturate nonlinearly at relatively low levels without triggering large-scale crashes, even though confinement degradation worsens as $β$ increases. In contrast, in an alternative configuration with nearly zero magnetic shear, ideal interchange modes induce a pressure crash at $β= 1\%$. These results suggest that the standard W7-X configuration might have a soft $β$-limit that is fairly immune to major MHD events, which enhances the appeal of the stellarator approach to steady-state fusion reactors. |
| title | Benign saturation of ideal ballooning instability in a high-performance stellarator |
| topic | Plasma Physics |
| url | https://arxiv.org/abs/2404.01966 |