Author: Reece, C.E.
Paper Title Page
TUPO042 RF Results of Nb Coated SRF Accelerator Cavities via HiPIMS 427
 
  • M.C. Burton, A.D. Palczewski, H.L. Phillips, C.E. Reece, A-M. Valente-Feliciano
    JLab, Newport News, Virginia, USA
  • R.A. Lukaszew
    The College of William and Mary, Williamsburg, Virginia, USA
  
  Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
Bulk Nio­bium (Nb) SRF (su­per­con­duct­ing radio fre­quency) cav­i­ties are cur­rently the pre­ferred method for ac­cel­er­a­tion of charged par­ti­cles at ac­cel­er­a­tor fa­cil­i­ties around the world. Since the SRF phe­nom­ena oc­curs within a shal­low depth of 40 nm (for Nb), a pro­posed op­tion has been to de­posit a su­per­con­duct­ing Nb thin film on the in­te­rior of a cav­ity made of a suit­able al­ter­na­tive ma­te­r­ial such as cop­per or alu­minum. While this ap­proach has been at­tempted in the past using DC mag­netron sput­ter­ing (DCMS), such cav­i­ties have never per­formed at the bulk Nb level. How­ever, new en­er­getic con­den­sa­tion tech­niques for film de­po­si­tion offer the op­por­tu­nity to cre­ate suit­ably thick Nb films with im­proved den­sity, mi­crostruc­ture and ad­he­sion com­pared to tra­di­tional DCMS. One such tech­nique that has been de­vel­oped some­what re­cently is ’High Power Im­pulse Mag­netron Sput­ter­ing’ (HiP­IMS). Here we re­port early re­sults from var­i­ous thin film coat­ings car­ried out on 1.3 GHz Cu Cav­i­ties, a 1.5 GHz Nb cav­ity and small Cu coupon sam­ples coated at Jef­fer­son Lab using HiP­IMS. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO042  
About • paper received ※ 12 September 2018       paper accepted ※ 21 September 2018       issue date ※ 18 January 2019  
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TUPO043 New Progress with HF-free Chemical Finishing for Nb SRF Cavities 431
 
  • H. Tian, J. Carroll, C.E. Reece, B. Straka
    JLab, Newport News, Virginia, USA
  • T.D. Hall, M.E. Inman, R. Radhakrishnan, E.J. Taylor
    Faraday Technology, Inc., Clayton, Ohio, USA
  
  Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
Jef­fer­son Lab has im­ple­mented a bipo­lar pulsed elec­trop­o­l­ish­ing sys­tem for final chem­i­cal pro­cess­ing of nio­bium SRF cav­i­ties. This FARA­DAYIC bi-po­lar elec­trop­o­l­ish­ing (BPEP) has been ap­plied to sin­gle cells, a 7-cell CEBAF C100 cav­ity, and to 9-cell TESLA-style cav­i­ties.* As a mech­a­nis­tic char­ac­ter­i­za­tion of the process emerges, the crit­i­cal role played by the local cur­rent den­sity dur­ing each ca­thodic pulse is be­com­ing clear. This in­flu­ences sys­tem and op­er­a­tional pa­ra­me­ter re­fine­ment. We pre­sent cur­rent process pa­ra­me­ters, re­moval char­ac­ter­i­za­tion, and rf per­for­mance of the processed cav­i­ties. This is the fruit of col­lab­o­ra­tive work be­tween Jef­fer­son Lab and Fara­day Tech­nol­ogy, Inc. di­rected to­ward the rou­tine com­mer­cial­iza­tion and in­dus­tri­al­iza­tion of nio­bium cav­ity pro­cess­ing. We also pre­sent sup­port­ing data from con­trolled-pa­ra­me­ter coupon stud­ies
* E.J. Taylor, et al. "Electrochemical system and method for electropolishing superconductive radio frequency cavities" U.S. Pat. No. 9,006, 147 (& international counterparts) issued April 14, 2015. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO043  
About • paper received ※ 12 September 2018       paper accepted ※ 19 September 2018       issue date ※ 18 January 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)