München 2019 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P 17: Helmholtz Graduate School VI

P 17.3: Vortrag

Donnerstag, 21. März 2019, 15:00–15:25, HS 17

2D impurity ion flow characteristics in different Wendelstein 7-X island divertor configurations — •Valeria Perseo¹, Ralf König¹, Dorothea Gradic¹, Oliver Patrick Ford¹, Florian Effenberg², David Ennis³, and Thomas Sunn Pedersen¹ for the The Wendelstein 7-X Team collaboration — ¹Max Planck Insitut für Plasmaphysik, Greifswald, Germany — ²University of Wisonsin, Madison, USA — ³Auburn University, Auburn, USA

The last campaign of Wendelstein 7-X (W7-X) was characterized by the island divertor. This concept exploits the stellarator intrinsic magnetic island topology, that is inherently 3D. In this context, a system able to measure 2D Doppler velocity patterns, such as Coherence Imaging Spectroscopy (CIS), is helpful to understand and confirm the basics of the impurity flow physics. The CIS diagnostic is a camera-based interferometer able to detect wavelength variation of the order of tens of pm (∼tens km/s) of an impurity selected by a narrow bandpass filter. A modulation pattern encoding the spectral line properties is generated by the usage of birefringent crystals. Two systems, set up in order to monitor the conditions of the same divertor module from nearly perpendicular lines of sight, have been designed for W7-X. Flows and line emissions have been recorded under different magnetic and plasma configurations, characterizing the behavior of the intrinsic carbon impurities. The measurements are compared with EMC3-EIRENE simulations, highlighting the presence of counter-streaming flows around the magnetic islands.