Nitronic 50 Steel as a Structural Material for EU-DEMO's Toroidal Field Coils

We report the results of an exploratory design study for Nitronic 50 (N50) Toroidal Field (TF) coils for the EU-DEMO fusion power plant. N50 is a super-austenitic steel that has a yield stress (𝝈 𝒚) of up to 1500 MPa at 4 K, 50% higher than the conventional structural steels (e.g., 316LN) that have been considered for EU-DEMO so far. 2D mechanical analyses have been performed on the inner legs of 30 different layer-wound and graded TF coil designs from the Swiss Plasma Center (SPC), with different current per turn's (𝑰 𝒕 's) and discharge time constants (𝝉 𝒅 's) while maintaining the same ampere-turns in the Winding Pack (WP). We show that there is a wide range of 𝑰 𝒕 and 𝝉 𝒅 parameter space that allows N50 coils with radial thicknesses of