Robust avoidance of edge-localized modes alongside gradient formation in the negative triangularity tokamak edge
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arXiv
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| Main Authors: | , , , , , , , , , |
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| Format: | Preprint |
| Published: |
2023
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| _version_ | 1866909070539096064 |
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| author | Nelson, A. O. Schmitz, L. Paz-Soldan, C. Thome, K. E. Cote, T. B. Leuthold, N. Scotti, F. Austin, M. E. Hyatt, A. Osborne, T. |
| author_facet | Nelson, A. O. Schmitz, L. Paz-Soldan, C. Thome, K. E. Cote, T. B. Leuthold, N. Scotti, F. Austin, M. E. Hyatt, A. Osborne, T. |
| contents | In a series of high performance diverted discharges on DIII-D, we demonstrate that strong negative triangularity (NT) shaping robustly suppresses all edge-localized mode (ELM) activity over a wide range of plasma conditions: $\langle n\rangle=0.1-1.5\times10^{20}$m$^{-3}$, $P_\mathrm{aux}=0-15$MW and $|B_\mathrm{t}|=1-2.2$T, corresponding to $P_\mathrm{loss}/P_\mathrm{LH08}\sim8$. The full dataset is consistent with the theoretical prediction that magnetic shear in the NT edge inhibits access to ELMing H-mode regimes; all experimental pressure profiles are found to be at or below the infinite-$n$ ballooning stability limit. Importantly, we also report enhanced edge pressure gradients at strong NT that are significantly steeper than in traditional ELM-free L-mode plasmas and provide significant promise for NT reactor integration. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2305_13458 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Robust avoidance of edge-localized modes alongside gradient formation in the negative triangularity tokamak edge Nelson, A. O. Schmitz, L. Paz-Soldan, C. Thome, K. E. Cote, T. B. Leuthold, N. Scotti, F. Austin, M. E. Hyatt, A. Osborne, T. Plasma Physics In a series of high performance diverted discharges on DIII-D, we demonstrate that strong negative triangularity (NT) shaping robustly suppresses all edge-localized mode (ELM) activity over a wide range of plasma conditions: $\langle n\rangle=0.1-1.5\times10^{20}$m$^{-3}$, $P_\mathrm{aux}=0-15$MW and $|B_\mathrm{t}|=1-2.2$T, corresponding to $P_\mathrm{loss}/P_\mathrm{LH08}\sim8$. The full dataset is consistent with the theoretical prediction that magnetic shear in the NT edge inhibits access to ELMing H-mode regimes; all experimental pressure profiles are found to be at or below the infinite-$n$ ballooning stability limit. Importantly, we also report enhanced edge pressure gradients at strong NT that are significantly steeper than in traditional ELM-free L-mode plasmas and provide significant promise for NT reactor integration. |
| title | Robust avoidance of edge-localized modes alongside gradient formation in the negative triangularity tokamak edge |
| topic | Plasma Physics |
| url | https://arxiv.org/abs/2305.13458 |