First results from divertor operation in Wendelstein 7-X
Thomas Sunn Pedersen, for the W7-X Team
W7-X Team
Mardi 27/11/2018, 11h00-12h15
Salle René GRAVIER 506 rdc, CEA Cadarache

Stellarators provide a potentially attractive concept for fusion power production, owing to their intrinsic steady-state capabilities, and their lack of runaway electron issues. However, high confinement at high ion temperatures has in the past been an elusive goal, primarily owing to prompt orbit losses. This issue is addressed in the new generation of optimized stellarators. Wendelstein 7-X (W7-X) is a highly optimized stellarator experiment that went into operation in 2015. With a 30 cubic meter volume, a superconducting coil system operating at 2.5 T, and steady-state heating capability of eventually up to 10 MW, it was built to demonstrate the benefits of optimized stellarators at parameters approaching those of a fusion power plant. Operation phase 1.2 featured the full complement of 10 divertor units, ECRH heating with up to 10 gyrotrons, more than 30 diagnostic systems, and a pellet fueling system. This talk will give a general overview of the W7-X goals and capabilities, and describe results from divertor operation, including measurements and corrections of error fields, characterization of divertor heat loads, evidence of detachment, and operation at significantly higher densities (ne >1020 m-3), ion temperatures (Ti>3.5 keV), pulse lengths (>50 seconds), and stored energies (E>1 MJ) than in operation phase 1.1. Tests of the W7-X optimization will also be reported.



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