Sputter coating of Nb₃Sn into SRF cavity using stoichiometric target

Conference · Wed Jan 28 00:00:00 EST 2026 · JACoW

DOI:https://doi.org/10.18429/JACoW-NAPAC2025-WEP082· OSTI ID:3029827

Shakel, Md Sharifuzzaman ^[1]; Pudasaini, Uttar ^[2]; Eremeev, Grigory ^[3]; Valente-Feliciano, Anne-Marie ^[2]; Hani E. Elsayed-Ali, Hani Elsayed-Ali ^[1]

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1. Old Dominion U.
2. Jefferson Lab
3. Fermilab

Nb₃Sn has emerged as a leading alternative material due to its higher superconducting critical temperature (Tc) and superheating field (Hsh), promising a viable solution to the intrinsic performance limit currently faced by Nb superconducting radiofrequency (SRF) cavities. We sputter-coated Nb₃Sn inside Nb SRF cavity using a stoichiometric Nb₃Sn tube target in a DC cylindrical magnetron sputter coater. The target was fabricated by growing an estimated >20 μm thick Nb₃Sn layer on a Nb tube via Sn vapor diffusion using Jefferson Lab’s coating system. Approximately 150 nm thick Nb-Sn films were sputter-deposited onto flat Nb samples at positions representing the beam tubes and equator of a 2.6 GHz Nb cavity. Post-deposition annealing at 950 °C for 3 h resulted in the formation of Nb₃Sn. Microstructural analysis of the annealed films was carried out to investigate the morphology and structure of the Nb₃Sn films. Later, a 2.6  GHz Nb SRF cavity was coated with a ~1.2 μm thick sputtered Nb-Sn film using a stoichiometric Nb₃Sn target, followed by annealing. Cryogenic RF testing of the annealed cavity demonstrated a Tc of 17.8 K, indicating the formation of Nb₃Sn. After a light Sn recoating treatment, the cavity achieved a quality factor (Q0) of 6.7E+08 at lower field at 2.0 K.

• Research Organization: Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Old Dominion U.; Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
• Sponsoring Organization: US Department of Energy
• DOE Contract Number: 89243024CSC000002
• OSTI ID: 3029827
• Report Number(s): FERMILAB-CONF-25-0322-TD; oai:inspirehep.net:3119672
• Resource Type: Conference paper
• Conference Information: Journal Name: JACoW
• Country of Publication: United States
• Language: English