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P: Fachverband Plasmaphysik
P 25: Poster III
P 25.18: Poster
Donnerstag, 29. Februar 2024, 16:30–18:30, ELP 6: Foyer
Tungsten Observation at Wendelstein 7-X — •Birger Buttenschön1, Daihong Zhang1, Thomas Pütterich2, and W7-X Team1 — 1Max-Planck-Institut für Plasmaphysik, Greifswald, Germany — 2Max-Planck-Institut für Plasmaphysik, Garching, Germany
In the first part of the second operation phase of the Wendelstein 7-X (W7-X) stellarator, some 280 wall and divertor tiles were made from tungsten or a tungsten-coated material. Those tiles were located in differently loaded regions of the wall. The purpose was to investigate how plasma-wall interaction might lead to contamination of the plasma with tungsten. As a tool to assess the tungsten concentration in the plasma, vacuum-ultraviolet (VUV) spectroscopy is used in combination with 2D bolometry.
While a detailed analysis requires somewhat advanced fitting methods (e.g. for the 5nm quasi-continuum), first - mostly qualitative - results can be readily obtained from the measured VUV spectra. For example, the acquired data allows to roughly determine the tungsten concentrations in specific plasma discharges, and it is used to define a minimum tungsten concentration at which the VUV spectrometer registers a signal above noise.
This contribution shows a number of different tungsten experiments performed in W7-X, the corresponding VUV spectra and what can be learned from the existing data set.
Keywords: Fusion; Impurities; Spectroscopy; Stellarator