Preliminary design of the cold mass supports for the EU DEMO feeders

The Cold Mass Support (CMS) is a basic structural component of the feeder system of the EU DEMO tokamak. The function of this structural element is not only to provide support to the containment duct - wiring the cryogenic lines, electrical bus bars and instrumentation to the magnets - in terms of both gravity loads and Lorentz forces, but also to isolate the low-temperature elements from the ambient, minimising the (conductive and radiative) heat loads. In this work, we describe a simulation and optimisation procedure adopted for the preliminary design of the EU DEMO CMS, which makes use of finite-element analyses and a shape parameterisation based on Radial Basis Functions (RBF). Structural and thermal numerical grids are morphed from a baseline configuration, and complex shape variations are achieved by means of an advanced meshless procedure based on CAD parametric surfaces, respecting the given geometrical constraints. A response surface-based optimisation is finally performed, in order to obtain a preliminary CMS candidate able to fulfil both structural and thermal targets.