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.

doi:10.1103/physrevlett.131.195101

Title: Robust Avoidance of Edge-Localized Modes alongside Gradient Formation in the Negative Triangularity Tokamak Edge

Journal Article · 07 November 2023 · Physical Review Letters

DOI: https://doi.org/10.1103/physrevlett.131.195101 · OSTI ID:2008488

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;

; Cote, T. B.; Leuthold, N.; Scotti, F.;

;

General Atomics

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: ⟨n⟩ = 0.1 − 1.5 × 1020 m−3, Paux = 0 − 15 MW and |Bt| = 1 − 2.2 T, corresponding to Ploss/PLH08 ∼ 8. 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. Our present dataset also features edge pressure gradients in strong NT that are closer to an H–mode than a typical L-mode plasma, supporting the consideration of NT for reactor design.

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Research Organization:: General Atomics, San Diego, CA (United States)

Sponsoring Organization:: USDOE Office of Science (SC), Fusion Energy Sciences (FES)

Grant/Contract Number:: FC02-04ER54698; SC0022270; SC0022272; SC0020287; SC0016154; FG02-97ER54415; FG02-08ER54999; AC02-09CH11466; FG02-99ER54531

OSTI ID:: 2008488

Alternate ID(s):: OSTI ID: 2337930

Journal Information:: Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 19 Vol. 131; ISSN 0031-9007

Publisher:: American Physical Society (APS)Copyright Statement

Country of Publication:: United States

Language:: English

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