Greifswald 2024 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
P: Fachverband Plasmaphysik
P 20: Magnetic Confinement VI
P 20.2: Hauptvortrag
Donnerstag, 29. Februar 2024, 11:30–12:00, ELP 6: HS 3
Drift flows in the island divertor of W7-X — •Carsten Killer1, Sean Ballinger2, Seung-Gyou Baek2, Dario Cipciar1, Olaf Grulke1,3, Adrian von Stechow1, and Jim Terry2 — 1Max-Planck-Institut für Plasmaphysik, Greifswald, Germany — 2MIT Plasma Science and Fusion Center, Cambridge, MA, USA — 3Technical University of Denmark, Lyngby, Denmark
The plasma boundary in the W7-X stellarator is formed by a chain of intrinsic resonant magnetic islands that are partially intersected by the modular divertor targets. Transport of heat and particles in the island plasma is subject to the interplay of field-parallel gradients, drift flows and turbulent cross-field transport. Two new diagnostic tools, a gas-puff imaging system and a 2D array of Langmuir probes, provide insight into the role of poloidal and radial drift flows and the 3D equilibrium structure of plasma parameters. Stationary radial electric fields within the magnetic islands measured with probes are consistent with the direct imaging of poloidal drift flows with velocities of a few km/s. As parallel transport has to span several 100m of connection length to the divertor targets in W7-X, these drift flows on the island flux surfaces are a significant (and sometimes dominant) transport channel. We observe - sensitively depending on size and position of the magnetic island - multiple shear layers of opposing flows / electric fields with typical widths of just 1-2 cm. In addition, small poloidal electric fields and corresponding radial flows can be present in some scenarios. Turbulent radial transport levels are rather small, particularly when compared to the plasma edge in tokamaks.
Keywords: Stellarator; Scrape-Off Layer; plasma flows; Langmuir probes