Abstract: The Helical-Axis Advanced Stellarator (HELIAS) is the leading stellarator concept in Europe and developed at the Max-Planck-Institute for Plasma Physics (IPP), Greifswald, Germany. Based on the 5-field-period symmetry, the HELIAS-5B engineering design study emerged which aims at a stellarator power reactor designed for 3000 MW fusion power.
The stellarator confines hot plasma only by external superconducting field coils, which are very sensitive for the neutron flux, leading to a complex 3D topology of the magnetic configuration. These coils define the shape of the device and limit the space available outside the plasma chamber for the vacuum vessel and the in-vessel components required for breeding, shielding and heat removal.
The neutronic performance of the HELIAS fusion reactor needs to be assessed. This requires a suitable computational approach to simulate the generation of source neutrons in the plasma chamber and the neutron transport through the complex HELIAS geometry. The approach is based on the Monte Carlo (MC) particle transport technique applied with the Direct Accelerated Geometry Monte Carlo (DAGMC) method. Beside the neutron source is a suitable geometry description important to represent a simplified HELIAS geometry as good as possible in the simulation. For the first neutronic design analyses, like neutron wall loading, tritium breeding ratio, neutron flux distribution and shielding performance, a simplified HELIAS model with homogenized material for each functional layer is used.
The talk will present the development of the stellarator neutron source based on plasma physics simulation, challenges in CAD to MC geometry translation including different translation approaches, first neutronic design analyses and the shielding performance in comparison to the design values specified as limits for the radiation loads to the superconducting toroidal field coils of the DEMO tokamak.