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Title: Influence of Compaction During Reaction Heat Treatment on the Interstrand Contact Resistances of Nb 3Sn Rutherford Cables for Accelerator Magnets

Abstract

The high field superconducting magnets required for ongoing and planned upgrades to the Large Hadron Collider (LHC) will be wound with Nb 3Sn Rutherford cables for which reason studies of Nb 3Sn strand, cable, and magnet properties will continue to be needed. Of particular importance is field quality. Here, the amplitudes of multipoles in the bore fields of dipole and quadrupole magnets, induced by ramp-rate-dependent coupling currents, are under the control of the interstrand contact resistances-crossing strand, R c , adjacent strand, R a , or a combination of them, R eff. Although two decades ago it was agreed that for the LHC R c should be in the range 10-30 μΩ, more recent measurements of LHC quadrupoles have revealed R c values ranging from 95 to 230 μΩ. This paper discusses ways in which these values can be achieved. In a heavily compacted cable R eff can be tuned to some predictable value by varying the width of an included stainless steel (effectively “insulating”) core. But cables are no longer heavily compacted with the result that the crossing strands of the impregnated cable are separated by a thick epoxy layer that behaves like an insulating core. If a stainlessmore » steel core is actually present, Reff must be independent of core width. Since there is no guarantee that a fixed predetermined amount of interlayer separation could be reproduced from winding to winding it would be advisable to include a full width core.« less

Authors:
 [1]; ORCiD logo [1];  [1]; ORCiD logo [2];  [2];  [3]; ORCiD logo [3]
  1. The Ohio State Univ., Columbus, OH (United States)
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  3. The Univ. of Twente, Enschede (The Netherlands)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
OSTI Identifier:
1510751
Grant/Contract Number:  
AC02-05CH11231
Resource Type:
Accepted Manuscript
Journal Name:
IEEE Transactions on Applied Superconductivity
Additional Journal Information:
Journal Volume: 28; Journal Issue: 3; Journal ID: ISSN 1051-8223
Publisher:
Institute of Electrical and Electronics Engineers (IEEE)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Nb$_{3}$Sn accelerator magnets; Nb$_{3}$Sn Rutherford cables; Nb$_{3}$Sn strands; interstrand contact resistance

Citation Formats

Collings, Edward Collings, Sumption, Mike D., Majoros, Milan, Wang, Xiaorong, Dietderich, Daniel R., Yagotyntsev, Konstantin, and Nijhuis, Arend. Influence of Compaction During Reaction Heat Treatment on the Interstrand Contact Resistances of Nb3Sn Rutherford Cables for Accelerator Magnets. United States: N. p., 2018. Web. doi:10.1109/tasc.2018.2796595.
Collings, Edward Collings, Sumption, Mike D., Majoros, Milan, Wang, Xiaorong, Dietderich, Daniel R., Yagotyntsev, Konstantin, & Nijhuis, Arend. Influence of Compaction During Reaction Heat Treatment on the Interstrand Contact Resistances of Nb3Sn Rutherford Cables for Accelerator Magnets. United States. doi:10.1109/tasc.2018.2796595.
Collings, Edward Collings, Sumption, Mike D., Majoros, Milan, Wang, Xiaorong, Dietderich, Daniel R., Yagotyntsev, Konstantin, and Nijhuis, Arend. Tue . "Influence of Compaction During Reaction Heat Treatment on the Interstrand Contact Resistances of Nb3Sn Rutherford Cables for Accelerator Magnets". United States. doi:10.1109/tasc.2018.2796595. https://www.osti.gov/servlets/purl/1510751.
@article{osti_1510751,
title = {Influence of Compaction During Reaction Heat Treatment on the Interstrand Contact Resistances of Nb3Sn Rutherford Cables for Accelerator Magnets},
author = {Collings, Edward Collings and Sumption, Mike D. and Majoros, Milan and Wang, Xiaorong and Dietderich, Daniel R. and Yagotyntsev, Konstantin and Nijhuis, Arend},
abstractNote = {The high field superconducting magnets required for ongoing and planned upgrades to the Large Hadron Collider (LHC) will be wound with Nb3Sn Rutherford cables for which reason studies of Nb3Sn strand, cable, and magnet properties will continue to be needed. Of particular importance is field quality. Here, the amplitudes of multipoles in the bore fields of dipole and quadrupole magnets, induced by ramp-rate-dependent coupling currents, are under the control of the interstrand contact resistances-crossing strand, R c , adjacent strand, R a , or a combination of them, R eff. Although two decades ago it was agreed that for the LHC R c should be in the range 10-30 μΩ, more recent measurements of LHC quadrupoles have revealed Rc values ranging from 95 to 230 μΩ. This paper discusses ways in which these values can be achieved. In a heavily compacted cable R eff can be tuned to some predictable value by varying the width of an included stainless steel (effectively “insulating”) core. But cables are no longer heavily compacted with the result that the crossing strands of the impregnated cable are separated by a thick epoxy layer that behaves like an insulating core. If a stainless steel core is actually present, Reff must be independent of core width. Since there is no guarantee that a fixed predetermined amount of interlayer separation could be reproduced from winding to winding it would be advisable to include a full width core.},
doi = {10.1109/tasc.2018.2796595},
journal = {IEEE Transactions on Applied Superconductivity},
number = 3,
volume = 28,
place = {United States},
year = {2018},
month = {1}
}

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