Optimization of Filament Structure in NbTi Superconducting Wires in WST

This study optimized the structural design of NbTi superconducting wires using the analysis method combining finite element simulation with experiments. By adjusting the matrix material of the NbTi mono-filament billet, the overall deformation uniformity of the filaments was significantly improved. Considering both the optimal structural parameters obtained from simulations and the practical requirements of assembly feasibility and processing yield, the final design has been confirmed, with the matrix material of the NbTi mono-filament billet being Cu2Mn, and the spacing-to-diameter ratio (S/D) parameter and filament spacing of the NbTi multi-filament billet being 0.50 and 5.20 mm, respectively. Based on this design, NbTi multi-filament wire with 24 filaments and a copper-to-non-copper ratio of 7 was fabricated using conventional drawing and aging heat treatment processes. The wire was finally drawn to a diameter of 1.0 mm and subjected to superconducting performance tests. The results showed that, under 4.2 K and 4 T, the optimized design achieved a critical current density (Jc) of 3804 A/mm2, representing an 11.8% improvement compared with 3400 A/mm2 for the existing structure.