Göttingen 2025 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P 20: Magnetic Confinment Fusion/HEPP V

P 20.4: Vortrag

Donnerstag, 3. April 2025, 15:10–15:35, ZHG102

Plasma turbulence modeling in detached regimes — •Konrad Eder, Wladimir Zholobenko, Andreas Stegmeir, Matthias Bernert, David Coster, and Frank Jenko — MPG-IPP, Garching, Germany

Predictive studies of the plasma edge in fusion reactors -- particularly towards detachment -- require self-consistent modeling of turbulent transport involving an interplay of plasma, neutral gas, and impurities.

We present extensions to the edge turbulence code GRILLIX, which applies a drift-fluid plasma model and a diffusive neutral gas model. The latter has been upgraded to a 3-moment fluid, i.e. neutral gas density, momentum, and pressure. Particle recycling is modeled by introducing novel boundary conditions compatible with the Flux-Coordinate-Independent (FCI) approach, on which GRILLIX is based and which enables it to handle complex diverted geometries.

In simulations of an attached ASDEX-Upgrade (AUG) L-mode discharge we first investigate how the model extensions affect neutrals and plasma near the divertor. Next, the updated model is validated against a fully detached AUG discharge featuring an L-mode X-point radiator (XPR) as part of an L-H transition. We are able to reproduce the XPR structure (radiating >80% of input power), a first-of-its-kind for turbulence simulations, and find the simulations to be in good agreement with experimental measurements at the Outboard-midplane and the divertor. Finally, we analyze distinct interchange-type turbulence found near the XPR structure, which helps elucidate our understanding of the XPR regime.

Keywords: Tokamak physics; Plasma edge; Plasma-neutrals fluid turbulence; Divertor detachment; X-point radiator