Greifswald 2024 – scientific programme

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P: Fachverband Plasmaphysik

P 12: Poster II

P 12.5: Poster

Tuesday, February 27, 2024, 16:30–18:30, ELP 6: Foyer

Investigating density build-up in the W7-X island divertor — •Nassim Maaziz, Felix Reimold, Victoria Winters, David Bold, Frederik Henke, and Yuhe Feng — Max-Planck-Institute for Plasma Physics, Greifswald 17491, Germany

The island divertor has been proposed for power and particle exhaust in stellarators and is investigated as a viable solution for a reactor in the Wendelstein 7-X (W7-X) experiment. The divertor capabilities increase with higher divertor densities. However, significantly lower densities have been measured in the W7-X divertor in comparison to tokamaks. We assess the impact of the island field line pitch on the density build-up with EMC3-EIRENE modeling and comparing to experimental measurements. The modeling shows an increase of field line pitch leads to higher achievable divertor densities. A more fundamental understanding of the density build-up motivated the development of a simplified geometry model for the island divertor, which we study with EMC3-EIRENE. We look at both, the impact of the field line pitch as well as the effect of the divertor geometry. The beneficial effect on the density build-up of increasing the field line pitch has been observed in this simplified case. A close divertor geometry appears to provide significantly higher achievable densities.

Keywords: Wendelstein 7-X; Island Divertor; Scrape-off Layer; Modelling; EMC3-EIRENE