Göttingen 2025 – scientific programme
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P: Fachverband Plasmaphysik
P 7: Magnetic Confinment Fusion/HEPP IV
P 7.2: Talk
Tuesday, April 1, 2025, 14:15–14:40, ZHG102
Characterizing scenarios of suppressed anomalous impurity transport in W7-X — •Thilo Romba1, Felix Reimold1, Sebastian Bannmann1, Alejandro Banon Navarro2, Hugo Cu Castillo2, Oliver Ford1, Peter Zsolt Poloskei1, Markus Wappl1, Thomas Klinger1, and the W7-X team3 — 1Max Planck Institute for Plasma Physics, Greifswald, Germany — 2Max Planck Institute for Plasma Physics, Garching, Germany — 3O. Grulke et al 2024 Nucl. Fusion 64 112002
In view of dilution and radiative losses, the understanding and subsequent tailoring of impurity transport in fusion plasmas depicts a crucial step towards self-sustained burn. While the impurity transport in the Wendelstein 7-X stellarator is typically benign [Geiger19], certain experimental scenarios exhibit a central accumulation of impurities with transport of impurities reducing to neoclassical level [Romba23].
This work aims to characterize such scenarios. While a high density is identified as a necessary condition for impurity peaking to occur, no fundamental dependence on magnetic field configuration is identified. In addition to high density, a local normalized density gradient a/Lne above unity is identified as a necessary, yet not sufficient, condition for impurity accumulation to occur. Transport simulations across impurity species with different charges Z are found to match with neoclassical transport predictions, indicating a suppression of anomalous transport across impurities.
Keywords: Impurity transport; Wendelstein 7-X; Stellarator