Safety margins of the W7-X plasma vessel for the static case

The magnet of the WENDELSTEIN 7-X stellarator is based on five modules with 10 non-planar and four planar superconducting coils. Basic points of interest are the actual electromagnetic forces acting at the coils with the resultant stresses within the structural support and the question of safety of the plasma vessel. A FE-model has been created for the vessel with its ports which are attached to the outer vacuum vessel. Different calculations have been performed to get the displacements and stresses due to the main load cases. With respect to the yield limit, the contributions of the normal, shear and the equilibrium (v. Mises) stress have to be seen separately. The evaluation to get an overview of the safety margins can be very time consuming, since the model of the presented plasma vessel with all the ports within a module consists of ∼21 700 shell elements. To reduce the time needed, development of special codes [1] was necessary to do the postprocessing. The report contains results of the FE-calculations together with the indication of actual safety margins which are summarised with illustrations of high stressed regions.