Göttingen 2025 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P 7: Magnetic Confinment Fusion/HEPP IV

P 7.5: Vortrag

Dienstag, 1. April 2025, 15:30–15:55, ZHG102

Dependence of turbulent transport on the divertor flux expansion in ASDEX Upgrade — •Jan Pfennig, Wladimir Zholobenko, Andreas Stegmeir, Konrad Eder, Kaiyu Zhang, and Frank Jenko — Max Planck Institute for Plasma Physics, 85748 Garching b. Muenchen, Germany

Predictive turbulence simulations represent a key tool to describing and understanding the anomalous transport of particles and energy across magnetic flux surfaces of tokamak fusion devices, which is commonly believed to be the main factor determining their confinement properties, and thus economic viability. Previously, extensive validation efforts for the locally field-aligned fluid turbulence code GRILLIX against ASDEX Upgrade attached L-Mode have been performed and resulted in good agreement with both mean-field and turbulence diagnostics. As a successive step, simulations with similar physical parameters but in the geometry of the new AUG upper divertor are performed for different levels of low-field side divertor flux expansion. Due to the global, full-f capabilities of GRILLIX it is possible to connect the effect of local changes in magnetic geometry to both local and global changes in the turbulent transport. By these means it is possible to disentangle the purely geometrical gain in exhaust performance by poloidal flux expansion from that of turbulent cross-field transport. The simulation results show a strong influence of the flux expansion on divertor heat flux peaking while global properties such as input power, edge confinement time, outboard mid-plane profiles and in fact the turbulence in the complete plasma edge remain nearly unchanged.

Keywords: tokamak; turbulence; scrape off layer; advanced divertor configuration; plasma edge