Author: Spradlin, J.K.
Paper Title Page
SUPTEV010 Electrical and Thermal Properties of Cold-Sprayed Bulk Copper and Copper-Tungsten Samples at Cryogenic Temperatures 142
 
  • H. Pokhrel
    ODU, Norfolk, Virginia, USA
  • G. Ciovati, P. Dhakal, J.K. Spradlin
    JLab, Newport News, Virginia, USA
  • C.-J. Jing, A. Kanareykin
    Euclid TechLabs, Solon, Ohio, USA
 
  Funding: Work supported by the U.S. Department of Energy, Office of Science, SBIR grant DE-SC00195589
The development of high thermal conductivity coatings with pure copper or copper-tungsten alloy could be beneficial to improve the heat transfer of bulk Nb cavities for conduction cooling applications and to increase the stiffness of bulk Nb cavities cooled by liquid helium. Cold-spray is an additive manufacturing technique suitable to grow thick coatings of either Cu or CuW on a Nb substrate. Bulk (~5 mm thick) coatings of Cu and CuW were deposited on standard 3 mm thick, high-purity Nb samples and smaller samples with 2 mm x 2 mm cross section were cut for measuring the thermal conductivity and the residual resistivity ratio. The samples were subjected to annealing at different temperatures and a maximum RRR of ~130 and ~40 were measured for the Cu samples and CuW samples, respectively.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPTEV010  
About • Received ※ 21 June 2021 — Revised ※ 13 August 2021 — Accepted ※ 15 November 2021 — Issue date ※ 21 March 2022
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SUPTEV016 Samples for 3rd Harmonic Magnetometry Assessment of NbTiN-Based SIS Structures 164
 
  • D.R. Beverstock, J.R. Delayen, I.H. Senevirathne, J.K. Spradlin, A-M. Valente-Feliciano
    JLab, Newport News, Virginia, USA
  • C.Z. Antoine
    CEA-IRFU, Gif-sur-Yvette, France
  • J.R. Delayen, I.H. Senevirathne
    ODU, Norfolk, Virginia, USA
  • D. Manos
    The College of William and Mary, Williamsburg, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. NSF Grants PHY-1734075 and PHY-1416051, and DOE Awards DE-SC0010081 and DE-SC0019399.
In the quest for alternative superconducting materials to bring accelerator cavity performance beyond the bulk niobium (Nb) intrinsic limits, a promising concept uses superconductor-insulator-superconductor (SIS) thin film structures that allows magnetic flux shielding in accelerator cavities to higher fields [1]. Candidate materials for such structures are NbTiN as the superconductor and AlN as the insulator. We have demonstrated high quality NbTiN and AlN deposited by reactive DC magnetron sputtering (DCMS), both for individual layers and multilayers. Interface quality has been assessed for bilayer stacks with 250 nm NbTiN layers and AlN thicknesses from 30 nm down to1 nm. These SIS structures show continued sharp interfaces with total average roughness under 2 nm. The Hfp enhancement of the films will be examined with a 3rd harmonic magnetometry. The system is being designed and built in a continuing collaboration with CEA Saclay. It can measure 25 to 50 mm samples on a temperature controlled stage. This contribution presents an overview of the design of the 3rd harmonic magnetometer and the material properties assessment of standalone films and multilayer nanostructures.
[1] A. Gurevich, Applied Physics Letters, vol. 88, p. 012511, 2006.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPTEV016  
About • Received ※ 22 June 2021 — Accepted ※ 10 November 2021 — Issue date; ※ 16 May 2022  
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