Author: Pudasaini, U.
Paper Title Page
WEPA30 Nb3Sn Coating of a 2.6 GHz SRF Cavity by Sputter Deposition Technique 691
 
  • M.S. Shakel, W. Cao, H. Elsayed-Ali, Md.N. Sayeed
    ODU, Norfolk, Virginia, USA
  • G.V. Eremeev
    Fermilab, Batavia, Illinois, USA
  • U. Pudasaini, A-M. Valente-Feliciano
    JLab, Newport News, Virginia, USA
  
  Funding: Supported by DOE, Office of Accelerator R&D and Production, Contact No. DE-SC0022284, with partial support by DOE, Office of Nuclear Physics DE-AC05-06OR23177, Early Career Award to G. Eremeev.
Nb3Sn is of in­ter­est as a coat­ing for SRF cav­i­ties due to its higher tran­si­tion tem­per­a­ture Tc ~18.3 K and su­per­heat­ing field Hsh ~400 mT, both are twice that of Nb. Nb3Sn coated cav­i­ties can achieve high-qual­ity fac­tors at 4 K and can re­place the bulk Nb cav­i­ties op­er­ated at 2 K. A cylin­dri­cal mag­netron sput­ter­ing sys­tem was built, com­mis­sioned, and used to de­posit Nb3Sn on the inner sur­face of a 2.6 GHz sin­gle-cell Nb cav­ity. With two iden­ti­cal cylin­dri­cal mag­netrons, this sys­tem can coat a cav­ity with high sym­me­try and uni­form thick­ness. Using Nb-Sn mul­ti­layer se­quen­tial sput­ter­ing fol­lowed by an­neal­ing at 950°C for 3 hours, poly­crys­talline Nb3Sn films were first de­posited at the equiv­a­lent po­si­tions of the cav­ity’s beam tubes and equa­tor. The film’s com­po­si­tion, crys­tal struc­ture, and mor­phol­ogy were char­ac­ter­ized by en­ergy dis­per­sive spec­troscopy, X-ray dif­frac­tion, and atomic force mi­croscopy. The Tc of the films was mea­sured by the four-point probe method and was 17.61 to 17.76 K. Based on these stud­ies, ~1.2 mi­cron thick Nb3Sn was de­posited in­side a 2.6 GHz Nb cav­ity. We will dis­cuss first re­sults from sam­ples and cav­ity coat­ings, and the sta­tus of the coat­ing sys­tem. 		 
poster icon Poster WEPA30 [1.769 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA30  
About • Received ※ 03 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 22 August 2022
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPA31 Lower Temperature Annealing of Vapor Diffused Nb3Sn for Accelerator Cavities 695
 
  • J.K. Tiskumara, J.R. Delayen
    ODU, Norfolk, Virginia, USA
  • G.V. Eremeev
    Fermilab, Batavia, Illinois, USA
  • U. Pudasaini
    JLab, Newport News, Virginia, USA
  
  Nb3Sn is a next-gen­er­a­tion su­per­con­duct­ing ma­te­r­ial for the ac­cel­er­a­tor cav­i­ties with higher crit­i­cal tem­per­a­ture and su­per­heat­ing field, both twice com­pared to Nb. It promises su­pe­rior per­for­mance and higher op­er­at­ing tem­per­a­ture than Nb, re­sult­ing in sig­nif­i­cant cost re­duc­tion. So far, the Sn vapor dif­fu­sion method is the most pre­ferred and suc­cess­ful tech­nique to coat nio­bium cav­i­ties with Nb3Sn. Al­though sev­eral post-coat­ing tech­niques (chem­i­cal, elec­tro­chem­i­cal, me­chan­i­cal) have been ex­plored to im­prove the sur­face qual­ity of the coated sur­face, an ef­fec­tive process has yet to be found. Since there are only a few stud­ies on the post-coat­ing heat treat­ment at lower tem­per­a­tures, we an­nealed Nb3Sn-coated sam­ples at 800 C - 1000 C to study the ef­fect of heat treat­ments on sur­face prop­er­ties, pri­mar­ily aimed at re­mov­ing sur­face Sn residues. This paper dis­cusses the sys­tem­atic sur­face analy­sis of coated sam­ples after an­neal­ing at tem­per­a­tures be­tween 850 C and 950 C.  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA31  
About • Received ※ 02 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 07 August 2022 — Issue date ※ 02 September 2022
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)