Fluid-dynamic and thermo-mechanical analyses of the metallic steering mirror for the ECRH system of DTT

The steerable launcher mirrors accurately guide microwave beams into the plasma, which is a fundamental function within the Electron Cyclotron Resonance Heating (ECRH) system of the Divertor Tokamak Test (DTT) facility, currently being built in Frascati, Italy. Since the mirror is subjected to intense electromagnetic field variations, which could induce high loads leading to structural failure, it is essential to identify a trade-off between thermomechanical performance and an adequate material selection with lower electrical conductivity which limits the electromagnetic induced loads. This paper investigates the two main configurations of metallic mirrors: monolithic Inconel 718 and a bimetallic design combining Stainless Steel 316 L and CuCrZr. The study covers thermo-fluid dynamic and thermomechanical analyses to assess the mirror's resistance under the imposed heat flux conditions. Furthermore, a fatigue analysis is conducted to evaluate the component's life cycle. Finally, different configurations are compared, highlighting how the two main proposed solutions offer the best compromise between electromagnetic forces and thermomechanical stresses.