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P: Fachverband Plasmaphysik
P 7: Magnetic Confinment Fusion/HEPP IV
P 7.1: Hauptvortrag
Dienstag, 1. April 2025, 13:45–14:15, ZHG102
Impurity Transport in Wendelstein 7-X: Basics and Experimental Observations — •Birger Buttenschön1, Thomas Wegner1, Thilo Romba1, Daihong Zhang1, Felix Reimold1, Alice Bonciarelli1,2, and the W7-X Team1 — 1Max Planck Institute for Plasma Physics, Greifswald, Germany — 2Politecnico di Milano, Italy
The presence of impurities in a fusion plasma can have significant influence on the plasma performance. While impurities generally dilute the fuel and thus reduce fusion efficiency, their line radiation is often used in the boundary plasma to reduce power fluxes to plasma-facing components. A high concentration of impurities in the confined plasma and the resulting radiation, however, is a critical loss channel for plasma energy and can lead to a radiative collapse of the plasma.
In the optimized stellarator Wendelstein 7-X, plasma scenarios featuring high energy and particle confinement inherently tend to accumulate impurities in the plasma center due to inwards directed neoclassical convective transport in the turbulence reduced ion-root regime. Understanding the (impurity) transport mechanisms is therefore a crucial step on the path to maintaining plasma performance by adjusting the impurity content and radiation within tolerable ranges.
This talk will give an overview on impurity transport in stellarators, introducing both theoretically expected transport mechanisms and suitable impurity transport diagnostics. Recent findings on the impurity transport in W7-X will be presented.
Keywords: Fusion; Impurities; Transport; Stellarator