Indications of turbulence-optimized operation scenarios for Wendelstein 7-X

Adrian von Stechow

Max Planck Institute for Plasma Physics

Wednesday, October 28, 2020



PSFC Seminars

Abstract: The Wendelstein 7-X  stellarator at IPP Greifswald, Germany is optimized to have strongly reduced neoclassical transport compared to a classical stellarator, such that turbulent transport can in principle be a major loss channel. A diverse set of diagnostics as well as fueling and heating options, in part supported by MIT collaborations, give early but comprehensive indications that transport is indeed predominantly anomalous. Neoclassical transport calculations based on kinetic profiles, as well as direct measurements of turbulent fluctuations and anomalous impurity particle transport support the notion that W7-X is a turbulence-dominated experiment, and that performance improvements need to incorporate turbulence-optimized operation scenarios. This talk focuses on results from various turbulence diagnostics from the plasma core to the scrape-off layer, and showcases high-performance scenarios which imply that a certain degree of turbulence control is possible by tailoring the driving kinetic profile gradients. These findings are supported by gyrokinetic simulations which show that W7-X benefits from improved resilience against trapped electron modes through its quasi-isodynamic symmetry property.


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