Robust avoidance of edge-localized modes alongside gradient formation in the negative triangularity tokamak edge

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\...

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Bibliographic Details
Published in:arXiv.org 2023-05
Main Authors: 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
Format: Article
Language:English
Subjects:
Pressure gradients
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Summary: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.
ISSN:2331-8422
DOI:10.48550/arxiv.2305.13458