Smooth, homogeneous, high-purity Nb3Sn superconducting RF resonant cavity by seed-free electrochemical synthesis

Abstract

Workbench-size particle accelerators, enabled by Nb3Sn-based superconducting radio-frequency (SRF) cavities, hold the potential of driving scientific discovery by offering a widely accessible and affordable source of high-energy electrons and X-rays. Thin-film Nb3Sn RF superconductors with high quality factors, high operation temperatures, and high-field potentials are critical for these devices. However, surface roughness, non-stoichiometry, and impurities in Nb3Sn deposited by conventional Sn-vapor diffusion prevent them from reaching their theoretical capabilities. Here we demonstrate a seed-free electrochemical synthesis that pushes the limit of chemical and physical properties in Nb3Sn. Utilization of electrochemical Sn pre-deposits reduces the roughness of converted Nb3Sn by five times compared to typical vapor-diffused Nb3Sn. Quantitative mappings using chemical and atomic probes confirm improved stoichiometry and minimized impurity concentrations in electrochemically synthesized Nb3Sn. We have successfully applied this Nb3Sn to the large-scale 1.3 GHz SRF cavity and demonstrated ultra-low BCS surface resistances at multiple operation temperatures, notably lower than vapor-diffused cavities. Our smooth, homogeneous, high-purity Nb3Sn provides the route toward high efficiency and high fields for SRF applications under helium-free cryogenic operations.

References in corpus (8)

• A Review of the Properties of Nb3Sn and Their Variation with A15 Composition, Morphology and Strain State
• Surface impedance and optimum surface resistance of a superconductor with imperfect surface
• Superheating field of superconductors within Ginzburg-Landau theory
• Analysis of Nb3Sn surface layers for superconducting RF cavity applications
• Microwave Superconductivity
• Surface oxides, carbides, and impurities on RF superconducting Nb and Nb3Sn: A comprehensive analysis
• Thermodynamic route of Nb3Sn nucleation: Role of oxygen
• ZrNb(CO) RF superconducting thin film with high critical temperature in the theoretical limit

Cited by in corpus (3)

• Surface oxides, carbides, and impurities on RF superconducting Nb and Nb3Sn: A comprehensive analysis
• Microscopic Investigation of rf Vortex Nucleation in Nb3Sn Films Using a Near-Field Magnetic Microwave Microscope
• ${\Delta }_T$ Noise in Mesoscopic Hybrid Junctions: Influence of Barrier Strength and Thermal Bias