Séminaire de Etienne Rochepault

One of the primary applications of superconductors is the fabrication of electromagnets for large-scale scientific facilities, such as particle accelerators, fusion reactors, and magnetic resonance imaging (MRI) systems. While the NbTi alloy remains the most widely used superconducting material—particularly in the Large Hadron Collider (LHC)—alternative materials are actively being investigated. Among them, the Nb₃Sn intermetallic compound currently represents the most mature candidate for the upgrade of existing infrastructures and the development of future projects, such as the Future Circular Collider (FCC).

Although high-field magnets based on Nb₃Sn have been successfully demonstrated, their robustness and reproducibility under operational conditions still require further validation. The formation of the Nb₃Sn phase involves a specific heat treatment at approximately 650 °C, during which significant stresses and strains are generated. This is particularly critical as Nb₃Sn is intrinsically brittle, and its superconducting properties are strongly dependent on the mechanical state.

The processes involved in the fabrication of Nb₃Sn conductors and magnets will first be described, emphasizing the multi-scale, composite, and multi-physical nature of the material. The seminar will then focus on experimental and modeling approaches used to characterize the composite behavior of Nb₃Sn. In particular, homogenization methods developed to address its multi-scale features will be presented. Finally, perspectives will be discussed regarding the integration of stress and strain effects into the prediction of the overall multi-physical performance of superconducting magnets