Analysis of the magnet support structure for the plasma fusion experiment Wendelstein 7-X

Abstract

a b s t r a c tThe world's largest plasma fusion experimental device of the stellarator family named Wendelstein 7-X (W7-X) [http://www.ipp.mpg.de/ippcms/eng/for/projekte/w7x/index.html] is being built at the MaxPlanck-Institute for Plasma Physics (IPP) in Greifswald, Germany. The mission of the experiment is to prove the fusion reactor relevance of the stellarator principle [1,2].Main subject of this paper is the description of the numerical simulation of the highly complex and multiple nonlinear W7-X magnet system structure with the code ADINA. This code was chosen right from the start of the project and has later been used in parallel with the subsequently installed ANSYS and ABAQUS codes until now.The ADINA W7-X global structure model is the result of a long term R&D work on the superconducting coils and related support structure optimization. Despite the fact that W7-X is already in the assembly phase, there are still large structural analysis efforts going on. Their aim is to accompany the machine construction by evaluating specific assembly issues, non-conformities and design changes, but also to evaluate the operational limits of the experimental device which in many respects is an absolute prototype worldwide.

First measurements of error fields on W7-X using flux surface mappinga

“…In particular, it has been shown that error fields with toroidal mode number n = 1 can overload divertor targets at relatively modest levels of (relative) error field amplitude. Such fields can arise from a variety of sources including coil assembly [3], ferritic materials, and superconducting coil motion [4]. To compensate such fields, five water cooled copper trim coils have been installed outside the cryostat of the device [5,6].…”

The subspace iteration method – Revisited

“…This model was presented and studied in Ref. [21] and is a valuable model to identify the performance of the subspace iteration method.…”

Technical challenges in the construction of the steady-state stellarator Wendelstein 7-X

“…The approach includes intensive numerical studies with multiple parametric runs, taking into account the assembly tolerances achieved. Benchmarking between several independent FE global models was the key factor to eliminate all possible inaccuracies [31] and to define design values for each magnet system element. As a result, a tree of parametric FE models has been created and reused to support the assembly process of the machine and to assess proposed minor changes in the design and all reported non-conformities.…”