Observation of Marfes in the Wendelstein 7-X stellarator with inboard limiters. (11th July 2018)

• Record Type: Journal Article
• Authors: Wenzel, U.; Biedermann, C.; Kocsis, G.; Szepesi, T.; Blackwell, B.D.; Klose, S.; Knauer, J.; Krychowiak, M.; Stephey, L.; Schmitz, O.; Harris, J.; König, R.; Pedersen, T.S.
• Other Names: collab.
• Is Part Of: Nuclear fusion. Volume 58:Number 9(2018:Sep.)
• Publication Date: 2018-07-11
• Subjects: radiative condensation -- Marfe -- stellarator; Nuclear fusion -- Periodicals; 621.48405
• DOI: 10.1088/1741-4326/aacb86
• Languages: English
• ISSNs: 0029-5515

Abstract

Abstract: In the first operational campaign of the Wendelstein 7-X (W7-X) stellarator we observed Marfe-like radiation belts at the plasma edge. We describe and analyze the behaviour of these radiation belts, especially with respect to the high density inside the belt, with a set of suitable diagnostics. We present evidence suggesting that these Marfe-like radiation belts are triggered by a drop of the edge temperature below 30 eV. From this observation we draw the conclusion that the physical cause of Marfes in tokamaks and Marfe-like radiation belts in W7-X is the same, namely radiative condensation. Furthermore, both exhibit the device symmetry, i.e. axisymmetry in a tokamak and the fivefold stellarator symmetry in W7-X.