Highlights 2015

Research news from the division Plasma Edge and Wall

GLADIS: Quality assessment of the W7-X divertor successfully completed

The image shows a W7-X target during high heat flux loading with 10 MW/m² in GLADIS. The spotted glow of the surface at about 1000 °C is caused by the fibre structure of the CFC material.

From 2005 to 2010 a total of 60 prototypes for the actively cooled divertor targets of Wendelstein 7-X were tested. In this period of time a production technology fulfilling the requirements of long pulse operation was developed in cooperation with Plansee SE. The prototypes of the pre-series have confirmed the robustness of the finally selected design and technology. Prototypes specified for long pulse operation at 10 MW/m² were successfully loaded at 30 MW/m² in the high heat flux test facility GLADIS.

Owing to its two ion sources of 1 MW power each, its 8 m³ vacuum chamber and powerful water cooling, GLADIS offers the possibility to investigate small scale as well as full scale objects loaded with extremely high heat fluxes.

From 2011 to early 2015, 86 of the 970 delivered components were evaluated. For this purpose all CFC (carbon fibre composite) tiles were loaded with 100 cycles of 10 seconds duration at 10 MW/m². The temperature increase of the CFC tiles caused by the thermo-mechanical load was evaluated statistically. It was possible to show that in spite of the seemingly small tested fraction the probability of an undetected defective CFC tiles is negligibly low (<1×10-10)

Future investigations for the divertor of Wendelstein 7-X will focus on diagnostics for the infrared thermography as well as on tests of full divertor modules.

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