Simulations of edge and SOL turbulence in diverted negative and positive triangularity plasmas

Ulbl, Philipp; Stegmeir, A.; Told, D.; Merlo, G.; Zhang, K.; Jenko, F.

doi:10.1088/1741-4326/adfd70

Simulations of edge and SOL turbulence in diverted negative and positive triangularity plasmas

Journal Article · Mon Sep 01 00:00:00 EDT 2025 · Nuclear Fusion

DOI:https://doi.org/10.1088/1741-4326/adfd70· OSTI ID:2997896

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Max-Planck-Institute for Plasma Physics, Boltzmannstrasse, Garching (Germany)
Max-Planck-Institute for Plasma Physics, Boltzmannstrasse, Garching (Germany); University of Texas at Austin, TX (United States)

Optimizing the performance of magnetic confinement fusion devices is critical to achieving an attractive fusion reactor design. Negative triangularity (NT) scenarios have been shown to achieve excellent levels of energy confinement, while avoiding edge localized modes. Modeling turbulent transport in the edge and SOL is key in understanding the impact of NT on turbulence and extrapolating the results to future devices and regimes. Previous gyrokinetic turbulence studies have reported beneficial effects of NT across a broad range of parameters. However, most simulations have focused on the inner plasma region, neglecting the impact of NT on the outermost edge. In this work, we investigate the effect of NT in edge and scrape-off layer simulations, including the magnetic X-point and separatrix. For the first time, we employ a multi-fidelity approach, combining global, non-linear gyrokinetic simulations with drift-reduced fluid simulations, to gain a deeper understanding of the underlying physics at play. First-principles simulations using the GENE-X code demonstrate that in comparable NT and PT geometries, similar profiles are achieved, while the turbulent heat flux is reduced by more than 50% in NT. Comparisons with results from the drift-reduced fluid turbulence code GRILLIX suggest that the turbulence is driven by trapped electron modes. The parallel heat flux width on the divertor targets is reduced in NT, primarily due to a lower spreading factor S.

View Accepted Manuscript (DOE)

Research Organization:: The University of Texas at Austin, TX (United States)

Sponsoring Organization:: EUROfusion; USDOE

Grant/Contract Number:: FG02-04ER54742

OSTI ID:: 2997896

Journal Information:: Nuclear Fusion, Journal Name: Nuclear Fusion Journal Issue: 10 Vol. 65; ISSN 0029-5515; ISSN 1741-4326

Publisher:: IOP PublishingCopyright Statement

Country of Publication:: United States

Language:: English

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GENE-X
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negative triangularity
turbulence

Simulations of edge and SOL turbulence in diverted negative and positive triangularity plasmas

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