From Wendelstein 7-X to a Stellarator Reactor

Abstract

Wendelstein 7-X is a drift optimized stellarator with improved thermal and fast ion confinement. Additional optimization criteria are a stiff equilibrium configuration and MHD stability up to a volume averaged β of 5%. The main objectives are to demonstrate reactor relevant plasma performance under steady state conditions including power and particle exhaust with an island divertor. To that effect Wendelstein 7-X has superconducting coils with a maximum average magnetic field of 3 T and will be equipped with actively cooled plasma facing components for heat fluxes of up to 10 MW/m 2 . Besides fulfilling this research mission, the extrapolation from Wendelstein 7-X to a stellarator reactor will depend on the comparison with the results from other stellarators, the ITER results and here in particular the experience gained with α-particle heating and operating a nuclear device, and the possibility to extrapolate these results by first principle theory.