skip to main content
DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Implications of the strain irreversibility cliff on the fabrication of particle-accelerator magnets made of restacked-rod-process Nb3Sn wires

Abstract

The strain irreversibility cliff (SIC), marking the abrupt change of the intrinsic irreversible strain limit ε irr,0 as a function of heat-treatment (HT) temperature θ in Nb 3Sn superconducting wires made by the restacked-rod process (RRP ®), is confirmed in various wire designs. It adds to the complexity of reconciling conflicting requirements on conductors for fabricating magnets. Those intended for the high-luminosity upgrade of the Large Hardon Collider (LHC) at the European Organization for Nuclear Research (CERN) facility require maintaining the residual resistivity ratio RRR of conductors above 150 to ensure stability of magnets against quenching. This benchmark may compromise the conductors’ mechanical integrity if their ε irr,0 is within or at the bottom of SIC. In this coupled investigation of strain and RRR properties to fully assess the implications of SIC, we introduce an electro-mechanical stability criterion that takes into account both aspects. For standard-Sn billets, this requires a strikingly narrow HT temperature window that is impractical. On the other hand, reduced-Sn billets offer a significantly wider choice of θ, not only for ensuring that ε irr,0 is located at the SIC plateau while RRR ≥ 150, but also for containing the strain-induced irreversible degradation of the conductor’s critical-currentmore » beyond ε irr,0. This study suggests that HT of LHC magnets, made of reduced-Sn wires having a Nb/Sn ratio of 3.6 and 108/127 restacking architecture, be operated at θ in the range of 680 to 695 °C (when the dwell time is 48 hours).« less

Authors:
ORCiD logo [1];  [2];  [3];  [4];  [5]
  1. Univ. of Colorado, Boulder, CO (United States). Dept. of Physics; National Inst. of Standards and Technology (NIST), Boulder, CO (United States). Quantum Electromagnetics Division; Florida State Univ., Tallahassee, FL (United States). National High Magnetic Field Lab. (MagLab), Applied Superconductivity Center
  2. National Inst. of Standards and Technology (NIST), Boulder, CO (United States). Quantum Electromagnetics Division
  3. Florida State Univ., Tallahassee, FL (United States). National High Magnetic Field Lab. (MagLab), Applied Superconductivity Center
  4. Univ. of Colorado, Boulder, CO (United States). Dept. of Physics; National Inst. of Standards and Technology (NIST), Boulder, CO (United States). Quantum Electromagnetics Division
  5. National Inst. of Standards and Technology (NIST), Boulder, CO (United States). Statistical Engineering Division
Publication Date:
Research Org.:
Univ. of Colorado, Boulder, CO (United States); NIST, Boulder, CO (United States); Florida State Univ., Tallahassee, FL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25); National Science Foundation (NSF)
OSTI Identifier:
1505837
Report Number(s):
DOE-FSU-17657
Journal ID: ISSN 2045-2322; DMR-1157490
Grant/Contract Number:  
SC0010690; SC0017657; AC02-05CH11231
Resource Type:
Accepted Manuscript
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Volume: 9; Journal Issue: 1; Journal ID: ISSN 2045-2322
Publisher:
Nature Publishing Group
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY

Citation Formats

Cheggour, Najib, Stauffer, Theodore C., Starch, William, Goodrich, Loren F., and Splett, Jolene D.. Implications of the strain irreversibility cliff on the fabrication of particle-accelerator magnets made of restacked-rod-process Nb3Sn wires. United States: N. p., 2019. Web. doi:10.1038/s41598-019-41817-7.
Cheggour, Najib, Stauffer, Theodore C., Starch, William, Goodrich, Loren F., & Splett, Jolene D.. Implications of the strain irreversibility cliff on the fabrication of particle-accelerator magnets made of restacked-rod-process Nb3Sn wires. United States. doi:10.1038/s41598-019-41817-7.
Cheggour, Najib, Stauffer, Theodore C., Starch, William, Goodrich, Loren F., and Splett, Jolene D.. Tue . "Implications of the strain irreversibility cliff on the fabrication of particle-accelerator magnets made of restacked-rod-process Nb3Sn wires". United States. doi:10.1038/s41598-019-41817-7. https://www.osti.gov/servlets/purl/1505837.
@article{osti_1505837,
title = {Implications of the strain irreversibility cliff on the fabrication of particle-accelerator magnets made of restacked-rod-process Nb3Sn wires},
author = {Cheggour, Najib and Stauffer, Theodore C. and Starch, William and Goodrich, Loren F. and Splett, Jolene D.},
abstractNote = {The strain irreversibility cliff (SIC), marking the abrupt change of the intrinsic irreversible strain limit εirr,0 as a function of heat-treatment (HT) temperature θ in Nb3Sn superconducting wires made by the restacked-rod process (RRP®), is confirmed in various wire designs. It adds to the complexity of reconciling conflicting requirements on conductors for fabricating magnets. Those intended for the high-luminosity upgrade of the Large Hardon Collider (LHC) at the European Organization for Nuclear Research (CERN) facility require maintaining the residual resistivity ratio RRR of conductors above 150 to ensure stability of magnets against quenching. This benchmark may compromise the conductors’ mechanical integrity if their εirr,0 is within or at the bottom of SIC. In this coupled investigation of strain and RRR properties to fully assess the implications of SIC, we introduce an electro-mechanical stability criterion that takes into account both aspects. For standard-Sn billets, this requires a strikingly narrow HT temperature window that is impractical. On the other hand, reduced-Sn billets offer a significantly wider choice of θ, not only for ensuring that εirr,0 is located at the SIC plateau while RRR ≥ 150, but also for containing the strain-induced irreversible degradation of the conductor’s critical-current beyond εirr,0. This study suggests that HT of LHC magnets, made of reduced-Sn wires having a Nb/Sn ratio of 3.6 and 108/127 restacking architecture, be operated at θ in the range of 680 to 695 °C (when the dwell time is 48 hours).},
doi = {10.1038/s41598-019-41817-7},
journal = {Scientific Reports},
number = 1,
volume = 9,
place = {United States},
year = {2019},
month = {4}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Save / Share: