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P: Fachverband Plasmaphysik

P 11: Poster I

P 11.34: Poster

Mittwoch, 22. März 2023, 14:00–15:30, HSZ EG

Helium exhaust and impurity transport in W7-X — •Thilo Romba, Felix Reimold, Thomas Klinger, and W7-X team — Max-Planck-Institut for Plasmaphysik, 17491 Greifswald, Deutschland

The precise monitoring of the impurity content and the understanding of the transport mechanisms is crucial for future fusion reactor operation due to the associated restrictions to the operational parameter space via dilution and increased radiative losses.

This work aims to analyze the transport of impurities in the confined region of the optimized stellarator Wendelstein 7-X (W7-X) [1] with focus on the fusion ash helium. Local impurity densities are measured using charge exchange recombination spectroscopy (CXRS) [2]. While CXRS allows to measure profiles of densities of individual impurity charge states, it has a low sensitivity to the transport coefficients in steady state scenarios [3]. To increase the sensitivity to the transport coefficients in those scenarios, modulated impurity sources outside the confined region are used.

The impurity transport will also be assessed in transient phases of neutral beam heated plasmas. In these scenarios it was found that impurity transport is dominated by inwards directed neoclassical convection and impurity density peaking is observed [4]. This work aims to extend this analysis to different magnetic configurations and impurity species.

[1] Erckmann 1997, [2] Fonck 1985, [3] Romba, in preparation [4] Romba, in preparation