Quantitative comparison of impurity transport in turbulence reduced and enhanced scenarios at Wendelstein 7-X
Autor
Alcusón, J.A.
Wegner, Th.
Dinklage, A.
Langenberg, A.
Bähner, J.P.
Buttenschön, B.
Edlund, E.M.
Fuchert, G.
García-Regaña, J.M.
Grulke, O.
Huang, Z.
Porkolab, M.
Stechow, A.V.
Zocco, A.
Editor
IOP PublishingFecha
2023Materia
Turbulent transportImpurity transport
Stellarator
Plasma
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We assess the turbulent particle transport being responsible for the limitation of the confinement and, thus, the overall performance of the neoclassically optimized stellarator Wendelstein 7-X. The radial particle transport is experimentally inferred from the evaluation of impurity injection into turbulence reduced and enhanced plasma scenarios revealing a completely different confinement behavior. The impact of the density gradient on the turbulent ion transport is theoretically estimated using large-scale non-linear gyro-kinetic simulations enabling, for the first time in Wendelstein 7-X, a quantitative comparison to the experimentally assessed impurity transport properties. We demonstrate that impurity transport in most of the Wendelstein 7-X discharges, up to now impossible to cover only with neoclassical estimations, is dominated by turbulence and can be modelled via gyro-kinetic simulations.