Speaker
Description
Physical Vapor Deposition (PVD) of A15 Nb3Sn thin films on copper (Cu) substrates offers a high-performance pathway for 4.2 K SRF cavity operation, combining higher critical temperatures with the superior thermal stability of Cu. Overcoming challenges related to Cu-Sn interdiffusion, Sn volatility, and low substrate thermal budgets requires tailored deposition dynamics and interface engineering.
Recent progress utilizes energetic PVD techniques such as DC sputtering and HiPIMS integrated with thin diffusion barriers (e.g., Nb or Ta) and SIS multilayer architectures. These nanometer-scale dielectric and superconducting interlayers prevent Cu contamination while providing magnetic screening to delay flux penetration beyond Hc1. Precise stoichiometry control (25at. % Sn) and interface optimization yield dense, uniform A15 phase formation with reduced residual resistance, advancing scalable Nb3Sn on Cu technology for next-generation particle accelerators.