Observation of Marfes in the Wendelstein 7-X stellarator with inboard limiters

Date

2018

Authors

Wenzel, Uwe
Biedermann, Christoph
Kocsis, Gábor
Szepesi, Tamás
Blackwell, Boyd
Klose, Sören
Knauer, Jens P
Krychowiak, M
Stephey, Laurie A
Schmitz, O.

Journal Title

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Volume Title

Publisher

IOP Publishing

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.

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Citation

Source

Nuclear Fusion

Type

Journal article

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Restricted until

2037-12-31