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Development of Single-Strand Excitation Rig for Probing Current Sharing in Nb3Sn Rutherford Cable at 4.2K up to 15 Tesla

This work focuses on the development of a rig for measuring current sharing in Nb3Sn Rutherford cables at high magnetic fields. The goal is to improve the understanding of interstrand-contact resistance and current redistribution in these cables for large-scale high-field applications.

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Development of Single-Strand Excitation Rig for Probing Current Sharing in Nb3Sn Rutherford Cable at 4.2K up to 15 Tesla

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  1. Development of single-strand excitation rig for probing current sharing in Nb3Sn Rutherford Cable at 4.2K up to 15 Tesla The Ohio State University C.J. Kovacs M.D. Sumption E.W. Collings Special Thanks B&G Tool

  2. Acknowledgements This work was supported by the U.S. Department of Energy, High Energy Physics university grant DE-FG02-95ER4090

  3. Background • Nb3Sn superconducting strands are the likely candidate for next generation: [1] • large-scale high-field applications • LHC luminosity upgrade • Interstrand-contact resistance (ICR) and current sharing in Rutherford Cables • Small: AC-loss, Magnetization • Large: low current sharing • current redistribution • Strands and Cable Architectures • Versus applied field • Small scale tests  newer technologies A. Zlobin, APT Seminar 2008 : Nb3Sn Accelerator Magnet R&D and LHC Luminosity Upgrades • M.D. Sumption et al. Cryogenics 52 91-99 2012

  4. OSU cable-loss measurements E. W. Collings et al.Adv. Cryo. Eng. ICMC Vol. 52 (2006) E. W. Collings et al. IEEE trans. App. Supercon. Vol. 17, No. 2 (2007) • Nb3Sn Un-cored/Cored Rutherford Cables • Cable Prep. (Pressures, Pre-treat, HT) • Core materials (MgO, S-glass, S.S.) • Cross-over/Adjacent ICR • AC-loss • ICR He-loss calormetry

  5. FRESCA • Nb3Sn Rutherford cable testing • MQE • Jc • ICR • Quench Propagation • ~1 meter long Dipole • M.D. Sumption et al. Cryogenics 52 91-99 2012 G. Ambrosio “Design of a sample holder for Nb3Sn Cable test at Fresca” TD-04-022

  6. Desired Characteristics of a small-scale system • What we need • Low operational cost • Helium usage • Low cable consumption • Low turn-around time • Examine cable preparation procedures • Pressure (HT and epoxy) • HT environment • Epoxy-insulation schemes • Small size (60mm bore) • Non-magnetic

  7. Background • Single cable preparation  magnet preparation • Insulation • HT w/ pressure • Epoxy impreg • Single-strand current injection • Quench excitation of strand • Current redistribution to neighboring strands • Quick screening of various cable constructions/prep • Small scale (60 mm bore magnet)

  8. Design CAD Bending Radius ≈ 8mm • 316L S.S. • Ti-6Al-4V Screws • Impreg ports • Sample port

  9. Design CAD • 316L S.S. • Ti-6Al-4V Screws • Sample port

  10. Design CAD • Ti-6Al-4V • High-Temp Lubricant

  11. Design CAD • Cu 10100 • Ti Screws • Alumina Insulator

  12. Design CAD • Cu 10100 • Transfer Region • Short length (Tube Furnace)

  13. Sample Preperation: Preforming

  14. Sample Preperation: Mounting Transverse pressures 0-15 MPa

  15. Sample Preperation: Mounting • Keeping Ti-6Al-4V fasteners under ~250 MPa M. Vanderhasten et al. Metalurgija. 2005; 11:195-200

  16. Sample Preperation: Mounting

  17. Sample Preperation: Mounting • 1200A w/ helium-cooled leads • Trans Pressure 0-15MPa • Epoxy Impregnation capability* • Instumentation ports • Versatile • Rutherford Cable w/ S-glass sheath

  18. Conclusions/Future Work • Designed a fixture to perform single-strand excitation measurements on Nb3Sn Rutherford Cable. • Make initial measurements of single-strand excitation and ICR & current redistribution. • Graphite Paste Heaters • 16-bit DAQ acquisition Labview • Hall-Probe Array

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