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Title: Further Heat Treatment Optimizations for Nb3Sn Conductors: From Wires to Cables

Abstract

© 2002-2011 IEEE. Accelerator magnets made with Nb3Sn superconducting coils are currently the most viable candidate technology for increasing the luminosity and energy of particle accelerators like the LHC. Today, the most developed Nb3Sn wire technology is the restacked rod process (RRP) wire manufactured by Bruker. RRP wires normally undergo a reaction heat treatment after coil winding which consists of three stages, one at 210 °C, one at 400 °C, and one at ∼660 °C spending roughly 48 h at each stage. The last stage of this heat treatment activates the solid-state diffusion which forms the Nb3Sn, whereas the first two stages have been historically used to 'mix' the Cu and Sn in order to avoid liquefaction of the low melting temperature phases. Recently, the second stage was studied and optimized to improve critical current density in RRP wires by controlling the kinetics triggered when the Cu-Nb-Sn ternary phase ('Nausite') forms; the first stage however, has a negligible impact on the critical current density of RRP wires, and instead focuses on reducing the probability of Sn leaking from the wires. These instances of Sn leaks are often referred to as 'Sn bursts.' In this paper, we explore Sn bursting onmore » Rutherford cables made with RRP wires in an attempt to better understand the threat of Sn bursts for future accelerator magnets using modern RRP wires. It was found that the Sn burst prevention mechanism, facilitated by the 210 °C stage, can be achieved in a fraction of the time, and that the modern RRP wires are less likely to observe Sn bursting. This new knowledge has enabled us to further understand and optimize the heat treatment of RRP wires for future accelerator magnets.« less

Authors:
; ; ;
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:
1564058
DOE Contract Number:  
AC02-05CH11231
Resource Type:
Journal Article
Journal Name:
IEEE Transactions on Applied Superconductivity
Additional Journal Information:
Journal Volume: 29; Journal Issue: 5
Country of Publication:
United States
Language:
English

Citation Formats

Sanabria, Charlie, Pong, Ian, LaLonde, Luc Paul, and Prestemon, Soren. Further Heat Treatment Optimizations for Nb3Sn Conductors: From Wires to Cables. United States: N. p., 2019. Web. doi:10.1109/tasc.2019.2899498.
Sanabria, Charlie, Pong, Ian, LaLonde, Luc Paul, & Prestemon, Soren. Further Heat Treatment Optimizations for Nb3Sn Conductors: From Wires to Cables. United States. doi:10.1109/tasc.2019.2899498.
Sanabria, Charlie, Pong, Ian, LaLonde, Luc Paul, and Prestemon, Soren. Thu . "Further Heat Treatment Optimizations for Nb3Sn Conductors: From Wires to Cables". United States. doi:10.1109/tasc.2019.2899498.
@article{osti_1564058,
title = {Further Heat Treatment Optimizations for Nb3Sn Conductors: From Wires to Cables},
author = {Sanabria, Charlie and Pong, Ian and LaLonde, Luc Paul and Prestemon, Soren},
abstractNote = {© 2002-2011 IEEE. Accelerator magnets made with Nb3Sn superconducting coils are currently the most viable candidate technology for increasing the luminosity and energy of particle accelerators like the LHC. Today, the most developed Nb3Sn wire technology is the restacked rod process (RRP) wire manufactured by Bruker. RRP wires normally undergo a reaction heat treatment after coil winding which consists of three stages, one at 210 °C, one at 400 °C, and one at ∼660 °C spending roughly 48 h at each stage. The last stage of this heat treatment activates the solid-state diffusion which forms the Nb3Sn, whereas the first two stages have been historically used to 'mix' the Cu and Sn in order to avoid liquefaction of the low melting temperature phases. Recently, the second stage was studied and optimized to improve critical current density in RRP wires by controlling the kinetics triggered when the Cu-Nb-Sn ternary phase ('Nausite') forms; the first stage however, has a negligible impact on the critical current density of RRP wires, and instead focuses on reducing the probability of Sn leaking from the wires. These instances of Sn leaks are often referred to as 'Sn bursts.' In this paper, we explore Sn bursting on Rutherford cables made with RRP wires in an attempt to better understand the threat of Sn bursts for future accelerator magnets using modern RRP wires. It was found that the Sn burst prevention mechanism, facilitated by the 210 °C stage, can be achieved in a fraction of the time, and that the modern RRP wires are less likely to observe Sn bursting. This new knowledge has enabled us to further understand and optimize the heat treatment of RRP wires for future accelerator magnets.},
doi = {10.1109/tasc.2019.2899498},
journal = {IEEE Transactions on Applied Superconductivity},
number = 5,
volume = 29,
place = {United States},
year = {2019},
month = {8}
}