Magnet Design Activities at CEA for EU-DEMO LAR Baseline 2024

In 2024, a new EU-DEMO baseline (called LAR for Low Aspect Ratio) was released which substantially changed the constraints on the magnets systems, with a key driver for changes the magnet systems being mechanical considerations. This paper will briefly list changes in the new baseline, and give an overview of updates to the CEA design toolbox MADMACS, particularly the implementation of fatigue analysis for the pulsed central solenoid (CS), and consideration of hybrid low/high-temperature superconducting CS coils. The new fatigue tool is later used to perform sensitivity analysis on the assumed parameters for Walker exponent and residual stress, with results showing that further study of these parameters should be of high priority. Summaries of new preliminary toroidal field (TF) coil and CS designs, based on ITER-like approaches, are also given. The final TF design required modifications to the winding pack dimensions, and the CS could only meet all the requirements using HTS inner turns, new jacket materials, and relaxations in fatigue assumptions. Therefore, it is clear that the LAR baseline has not yet resolved the static and fatigue concerns for the magnet systems, when considering ITER-like TF and CS solutions, but that this may be possible with further development.