Assessment of the W7-X high heat flux divertor with thermo-mechanical analysis

Abstract

The Wendelstein 7-X is an experimental device designed with a stellarator magnetic confinement for stationary plasma operation (up to 30min). At the first stage, it is scheduled to start with an inertially cooled test divertor unit and a shorter plasma pulse operation up to 10s. After the completion of this stage, a water-cooled high heat flux (HHF) divertor will be installed for the steady-state operation phase. The divertor consists of individual target modules, which are sets of target elements armored with CFC tiles supported by a stainless steel structure and fed in parallel with manifolds. Detailed thermo-mechanical analysis of the target modules using the finite element method has been performed to validate and/or improve the elected design of the HHF divertor under operation. Different operating conditions have been studied and the effect of the variation of the convective heat flux pattern with localized heating loads as high as 10 MW/m2 onto the target elements has been computed. The analysis of the thermal response, stress distribution and deformation allowed a better understanding of the behavior of the divertor modules under operation and confirmed the suitability of the design.