RECENT RESULTS FROM Nb3Sn SINGLE CELL CAVITIES COATED AT JLAB

Conference · Thu Aug 01 00:00:00 EDT 2019

DOI:https://doi.org/10.18429/JACoW-SRF2019-MOP018· OSTI ID:1975499

Pudasaini, U. ^[1]; Eremeev, G. ^[2]; Reece, C. E. ^[2]; Ciovati, G. ^[2]; Parajuli, I. ^[3]; Sayeed, N. ^[3]; Kelley, M. J. ^[4]

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1. College of William and Mary, Williamsburg, VA (United States)
2. Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
3. Old Dominion Univ., Norfolk, VA (United States)
4. College of William and Mary, Williamsburg, VA (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

Because of superior superconducting properties (Tc ~ 18.3K, Hs h ~ 425 mT and ? ~ 3.1 meV) compared to niobium, Nb3Sn promise better RF performance (Q0 and Eacc) and/or higher operating temperature (2 K Vs 4.2 K) for SRF cavities. Nb3Sn-coated SRF cavities are produced routinely by depositing a few micron-thick Nb3Sn films inside of Nb cavities via tin vapor diffu-sion technique. Early results from Nb3Sn cavities coat-ed with this technique exhibited precipitous low field Q-slope, also known as Wuppertal slope. Several Nb3Sn single cell cavities coated at JLab appeared to exhibit similar Q-slope. RF testing of cavities and ma-terials study of witness samples were continuously used to modify the coating protocol. At best condition, we were able to produce Nb3Sn cavity with Q0 in ex-cess of ? 5×1010 at 2 K and ? 2×1010 at 4 K up the ac-celerating gradient of ~15 MV/m, without any signifi-cant Q-slope. In this presentation, we will discuss re-cent results from several Nb3Sn coated single-cell cavities linked with material studies of witness sam-ples, coating process modifications and the possible causative factors to Wuppertal slope.

• Research Organization: Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Nuclear Physics (NP)
• DOE Contract Number: AC05-06OR23177
• OSTI ID: 1975499
• Report Number(s): JLAB-ACC-19-2982; DOE/OR/23177-6247
• Country of Publication: United States
• Language: English