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P: Fachverband Plasmaphysik

P 5: Poster I

P 5.18: Poster

Dienstag, 31. August 2021, 14:00–16:00, P

Characterization and driving mechanisms of dominant Alfvén eigenmodes at the W7-X Stellarator — •Sara Vaz Mendes, Kian Rahbarnia, Christoph Slaby, Thomsen Henning, Jonathan Schilling, Christian Brandt, Matthias Borchardt, Ralf Kleiber, and Axel Könies — Max Planck Institute for Plasma Physics, Wendelsteinstr. 1, 17491 Greifswald, Germany

Electromagnetic Alfvén waves are often present in different scenarios of the W7-X stellarator plasmas. Induced magnetic fluctuations (between 100-450 kHz) were observed for 727 discharges during different magnetic configurations, heating scenarios and general plasma parameters. The measurements were performed using a system of 125 Mirnov coils, located in four out of five modules of W7-X.
The Alfvénic nature is proven through the scaling of dominant magnetic fluctuation frequencies with the plasma density. In addition, the correlation of the observed Alfvénic activity with different plasma parameters is being analyzed.
In the future operation of W7-X a bigger population of energetic particles (EPs) is expected and the possible resonant wave-particle transport of EPs must be avoided since it can result in degradation of plasma confinement or even damaging of plasma facing components. To better understand these risks the conditions for enhanced Alfvénic activity at W7-X are studied and possible driving mechanisms are discussed.