Mechanical and electrical characterization of composite conductors based on High-Temperature Superconducting tapes for fusion applications

This report presents the work carried out during an internship at CEA, within the framework of the PEPR Suprafusion project, which aims to develop technologies for nuclear fusion applications. The study focuses on the mechanical and electrical characterization of composite conductors based on High-Temperature Superconducting (HTS) tapes developed at CEA. The first part of the work involved analyzing the parameters and methodologies of the assembly process. Critical aspects were identified and addressed to improve both efficiency and reproducibility. In addition, metallographic analyses were performed on conductor cross-sections to better evaluate the geometry of the HTS tape and the quality of the brazing process. The second part of the work focused on the electrical characterization of the conductor through liquid nitrogen testing, with the objective of determining its critical current. A dedicated procedure was developed for data acquisition and analysis. Subsequently, mechanical characterization was carried out through tensile, com pression, bending, and torsion tests to evaluate the conductor’s behavior under applied stress and to determine its mechanical properties. After each mechanical test, new electrical measurements were performed to assess any degradation in the critical current. This approach allowed the identification of stress and strain thresholds beyond which the superconductor’s performance is compromised. Finally, a dedicated section investigates the stresses experienced by the HTS tape within the conductor during the heat treatment of the assembly process and the thermal contraction occurring under cryogenic conditions in liquid nitrogen.