Managing Sn-Supply to Tune Surface Characteristics of Vapor-Diffusion Coating of Nb₃Sn

Conference · Tue Feb 01 00:00:00 EST 2022

DOI:https://doi.org/10.18429/JACoW-SRF2021-TUPTEV013· OSTI ID:1905471

Pudasaini, U. ^[1]; Reece, C. E. ^[1]; Tiskumara, J. K. ^[2]

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1. Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
2. Old Dominion Univ., Norfolk, VA (United States)

Nb₃Sn promises better RF performance (Q and E_{acc}) than niobium at any given temperature because of superior superconducting properties. Nb₃Sn-coated SRF cavities are now produced routinely by growing a few microns thick Nb₃Sn films inside Nb cavities via the tin vapor diffusion technique. Sn evaporation and consumption during the growth process notably affect the quality of the coating. Aiming at favorable surface characteristics that could enhance the RF performance, many coatings were produced by varying Sn sources and temperature profiles. Coupon samples were examined using different material characterization techniques, and a selected few sets of coating parameters were used to coat 1.3 GHz single-cell cavities for RF testing. The Sn supply’s careful tuning is essential to manage the microstructure, roughness, and overall surface characteristics of the coating. We summarize the material analysis of witness samples and discuss the performance of several Nb₃Sn-coated single-cell cavities linked to Sn-source characteristics and observed Sn consumption during the film growth process.

• Research Organization: Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Nuclear Physics (NP)
• DOE Contract Number: AC05-06OR23177
• OSTI ID: 1905471
• Report Number(s): JLAB-ACC-21-3440; DOE/OR/23177-5258
• Resource Relation: Conference: International Conference on RF Superconductivity (20th), East Lansing, MI, USA, 28 June-02 July 2021
• Country of Publication: United States
• Language: English