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Stability measurements in Nb 3 Sn strands with various wire and sub-element diameters

Stability measurements in Nb 3 Sn strands with various wire and sub-element diameters. The Ohio State University C.J. Kovacs M.D. Sumption E.W. Collings M. Majoros X. Xu. Hyper Tech Research, Inc. X. Peng. Acknowledgements.

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Stability measurements in Nb 3 Sn strands with various wire and sub-element diameters

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  1. Stability measurements in Nb3Sn strands with various wire and sub-element diameters The Ohio State University C.J. Kovacs M.D. Sumption E.W. Collings M. Majoros X. Xu Hyper Tech Research, Inc. X. Peng

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

  3. Background • Nb3Sn superconducting strands are the likely canditate for next generation: [1] • large-scale high-field applications • LHC luminosity upgrade • some undulator and wiggler magnets. • Low-fields magneto-thermal instabilities limiting application performance. • Two types of co-existing characters: • self-field • magnetization-type. • RRR, Deff, strand diameter, and Jc. [2, 3] A. Zlobin, APT Seminar 2008 : Nb3Sn Accelerator Magnet R&D and LHC Luminosity Upgrades • M.D. Sumption et al. Cryogenics 52 91-99 2012 • M.D. Sumption Adv. Cryo. Eng. ICMC Vol. 56 CP1219 2010 • B. Bordini, L. Rossi IEEE Trans. App. Supercond. Vol. 19 No. 3 June 2009

  4. Motivation/Procedure • Instabilities measured on single-strands mounted using ITER barrels  lead to difficulties in magnets. [2] • V-I and V-H and Stability current measured for samples with varying RRR, Deff, strand diameter, and Jc (varying reaction) • V-I 0.2 A/s near transition • 0-2 Tesla V-B* • I-ramp 1 A/s • B-ramp 1 T/min • *One sample 0-3T

  5. Strand Parameters

  6. Sample Parameters Range Deff: 20-87µm RRR: 8-91 Strand Dia: 0.5-0.84mm 12 Jc: 743-2908 A/mm2 Twist Pitch: 15mm

  7. Stability Data 12T Jc= 2908 A/mm2 12T Jc= 743 A/mm2

  8. Stability Data 12T Jc= 1178 A/mm2 12T Jc= 1547 A/mm2

  9. Stability Data 12T Jc= 1840 A/mm2 12T Jc= 1267 A/mm2

  10. Stability Data 12T Jc= 1544 A/mm2 12T Jc= 1727 A/mm2

  11. Stability Data 12T Jc= 2067 A/mm2 12T Jc= 1494 A/mm2

  12. Stability Data 12T Jc= 1379 A/mm2 12T Jc= 1317A/mm2

  13. Stability Data 12T Jc= 1271 A/mm2 0-3T 12T Jc= 1614 A/mm2

  14. Stability Data Correlations

  15. Stability Data Correlations

  16. Stability Data Correlations

  17. Stability Data Correlations Deff React Deff-react/Deff ≈ 1 Deff-react/Deff < 1

  18. Stability Data Correlations

  19. Conclusions/Future Work • Clear inverse relationship between Deff and Js • Better fit with Deff-react • Of course RRR, Strand Diameter also important – dependence less pronounced for this data set • Measure additional Tube and RIT-type strands • Compare to stability models proposed by Sumption and Bordini-Rossi.

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