Approaches for quantitative study of divertor heat loads on W7-X

Aimed to show the fusion-reactor relevance of optimized stellarators, Wendelstein 7-X (W7-X) [1], as the world's largest stellarator (plasma volume 30 m(3), major radius 5.5 m, minor radius 0.5 m), completed successfully its first experimental campaign with island divertor in December 2017. To demonstrate the capabilities of steady-state operation with reactor-relevant plasma parameters, island divertor concept is commissioned for a tolerable plasma power and particle exhaust. Pre-defined magnetic islands at the plasma boundary are cut open by the divertor plates, so that these open field lines will lead the unconfined plasmas to the graphite tiles, which are designed to allow a high power load of up to 10 MW/m(2).