Greifswald 2024 – wissenschaftliches Programm
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P: Fachverband Plasmaphysik
P 25: Poster III
P 25.15: Poster
Donnerstag, 29. Februar 2024, 16:30–18:30, ELP 6: Foyer
Onto Island Localized Modes in the Wendelstein 7-X scrape off layer — •Dario Cipciar1, Carsten Killer1, Jiri Adamek2, Olaf Grulke3, Kian Rahbarnia1, Christian Brandt1, and W7-X Team1 — 1Max- Planck-Institut für Plasmaphysik Greifswald, Germany — 2IPP of the CAS Prague, Czech republic — 3Technical University of Denmark, Lyngby, Denmark
In the Wendelstein 7-X stellarator scrape off layer, magnetic islands are present and partly intersected by divertor targets. Around the "O-point" of the islands, a region of uninterrupted, closed field lines can remain. Measurements with electric probes indicate that low frequency mode activity, which is also seen by other plasma diagnostics such as magnetics and X-ray tomography, is associated to this particular region. These modes challenge the current picture of the magnetic islands as stationary resonances of the external magnetic field. We investigate the possibility of local currents existing in the islands, which periodically modify the magnetic structure of the islands (compress and expand). These changes in the shape of the islands can lead to self-regulation of island transport channels might and provide an explanation to the observed low-frequency modulation of island density electron and ion temperature, and plasma potential.
Keywords: W7X; SOL; ILMs; Ion temperature; magnetic islands