Impact of spatially varying transport coefficients in EMC3-Eirene simulations of W7-X and assessment of drifts

Autor: David Bold, Felix Reimold, Holger Niemann, Yu Gao, Marcin Jakubowski, Carsten Killer, Victoria R. Winters, Nassim Maaziz, the W7-X Team
Jazyk: angličtina
Rok vydání: 2024
Předmět:
Zdroj: Nuclear Fusion, Vol 64, Iss 12, p 126055 (2024)
Druh dokumentu: article
ISSN: 1741-4326
0029-5515
DOI: 10.1088/1741-4326/ad845c
Popis: Modelling the scrape-off layer of a stellarator is challenging due to the complex magnetic 3D geometry. The here presented study analyses simulations of the scrape-off layer (SOL) of the stellarator Wendelstein 7-X (W7-X) using spatially varying diffusion coefficients for the magnetic standard configuration, extending our previous study (Bold et al 2022 Nucl. Fusion 62 106011). Comparing the EMC3-Eirene simulations with experimental observations, an inconsistency between the strike-line width (SLW) and the upstream parameters was observed. While to match the experimental SLW a particle diffusion coefficient D ≈ 0.2 m ^2 s ^−1 is needed, D ≈ 1 m ^2 s ^−1 is needed to get experimental separatrix temperatures of 50 eV at the given experimental heating power. We asses the impact of physically motivated spatially varying transport coeffients. Agreement with experimental data can be improved, but various differences remain. We show that drifts are expected to help overcome the discrepancies and, thus, the development of SOL transport models including drifts is a necessary next step to study the SOL transport of the W7-X stellarator.
Databáze: Directory of Open Access Journals