Diagnostic setup for investigation of plasma wall interactions at Wendelstein 7-X

• Published in: Fusion engineering and design Vol. 96-97; pp. 891 - 894
• Main Authors: Neubauer, Olaf, Biel, Wolfgang, Czymek, Guntram, Denner, Peter, Effenberg, Florian, Krämer-Flecken, Andreas, Liang, Yunfeng, Marchuk, Oleksandr, Offermanns, Guido, Rack, Michael, Samm, Ulrich, Schmitz, Oliver, Schweer, Bernd, Terra, Alexis
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.10.2015
• Subjects: Boundaries; Diagnostic; Diagnostic systems; Dispersions; High density; Interferometers; Island divertor; Plasma wall interactions; Reflectometers; Stellarator; Three dimensional; Walls; Diagnostic; Plasma wall interactions; Island divertor; Stellarator
• ISSN: 0920-3796; 1873-7196
• DOI: 10.1016/j.fusengdes.2015.06.102

•We are investigating plasma wall interactions at Wendelstein 7-X stellarator.•Steady state operation and island divertor are unique.•We are developing diagnostics for divertor plasma and plasma facing surfaces.•A multi-purpose fast manipulator allows for exposure of probes and samples.•Versatile endoscopes allow for local divertor spectroscopy from IR to UV. Wendelstein 7-X being the most advanced stellarator is currently prepared for commissioning at Greifswald. Forschungszentrum Jülich is preparing a research programme in the field of plasma wall interactions (PWI) by developing a dedicated set of diagnostic systems. The specific interest at Wendelstein 7-X is to understand PWI processes in presence of a 3D plasma boundary of an island divertor. Furthermore, for the first time steady state plasma at high density and low temperature in the divertor region will be available. Since PWI only could be understood in conjunction with the edge plasma properties the aim of the setup is to observe both the edge plasma as well as surface processes. For optimum combination of different diagnostic methods the edge diagnostic systems are aligned toroidally along one out of five magnetic islands. Main systems are a multipurpose fast probe manipulator, two gas boxes in opposite divertor modules together with two endoscopes each observing the divertor regions, a poloidal correlation reflectometer, a dispersion interferometer in the divertor, and VUV and X-ray spectroscopy in the plasma core. The concept of the diagnostic setup is presented in this paper.