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Self-Field Effects in Magneto-Thermal Instabilities for Nb-Sn Strands

Recent advancements in the critical current density (Jc) of Nb$_{3}$Sn conductors, coupled with a large effective filament size, have drawn attention to the problem of magnetothermal instabilities. At low magnetic fields, the quench current of such high Jc Nb$_{3}$Sn strands is significantly lower t...

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Autores principales: Bordini, B, Barzi, E, Fehér, S, Rossi, L, Zlobin, A V
Lenguaje:eng
Publicado: 2008
Materias:
Acceso en línea:https://dx.doi.org/10.1109/TASC.2008.921899
http://cds.cern.ch/record/1116072
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author Bordini, B
Barzi, E
Fehér, S
Rossi, L
Zlobin, A V
author_facet Bordini, B
Barzi, E
Fehér, S
Rossi, L
Zlobin, A V
author_sort Bordini, B
collection CERN
description Recent advancements in the critical current density (Jc) of Nb$_{3}$Sn conductors, coupled with a large effective filament size, have drawn attention to the problem of magnetothermal instabilities. At low magnetic fields, the quench current of such high Jc Nb$_{3}$Sn strands is significantly lower than their critical current because of the above-mentioned instabilities. An adiabatic model to calculate the minimum current at which a strand can quench due to magneto-thermal instabilities is developed. The model is based on an 'integral' approach already used elsewhere [1]. The main difference with respect to the previous model is the addition of the self-field effect that allows to describe premature quenches of non-magnetized Nb$_{3}$Sn strands and to better calculate the quench current of strongly magnetized strands. The model is in good agreement with experimental results at 4.2 K obtained at Fermilab using virgin Modified Jelly Roll (MJR) strands with a low Residual Resistivity Ratio (RRR) of the stabilizing copper. The prediction of the model at 1.9 K and the results of the tests carried out at CERN, at 4.2 K and 1.9 K, on a 0.8 mm Rod Re-Stack Process (RRP) strand with a low RRR value are discussed. At 1.9 K the test revealed an unexpected strand performance at low fields that might be a sign of a new stability regime.
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institution Organización Europea para la Investigación Nuclear
language eng
publishDate 2008
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spelling cern-11160722019-09-30T06:29:59Zdoi:10.1109/TASC.2008.921899http://cds.cern.ch/record/1116072engBordini, BBarzi, EFehér, SRossi, LZlobin, A VSelf-Field Effects in Magneto-Thermal Instabilities for Nb-Sn StrandsAccelerators and Storage RingsRecent advancements in the critical current density (Jc) of Nb$_{3}$Sn conductors, coupled with a large effective filament size, have drawn attention to the problem of magnetothermal instabilities. At low magnetic fields, the quench current of such high Jc Nb$_{3}$Sn strands is significantly lower than their critical current because of the above-mentioned instabilities. An adiabatic model to calculate the minimum current at which a strand can quench due to magneto-thermal instabilities is developed. The model is based on an 'integral' approach already used elsewhere [1]. The main difference with respect to the previous model is the addition of the self-field effect that allows to describe premature quenches of non-magnetized Nb$_{3}$Sn strands and to better calculate the quench current of strongly magnetized strands. The model is in good agreement with experimental results at 4.2 K obtained at Fermilab using virgin Modified Jelly Roll (MJR) strands with a low Residual Resistivity Ratio (RRR) of the stabilizing copper. The prediction of the model at 1.9 K and the results of the tests carried out at CERN, at 4.2 K and 1.9 K, on a 0.8 mm Rod Re-Stack Process (RRP) strand with a low RRR value are discussed. At 1.9 K the test revealed an unexpected strand performance at low fields that might be a sign of a new stability regime.CERN-AT-2008-003oai:cds.cern.ch:11160722008-07-11
spellingShingle Accelerators and Storage Rings
Bordini, B
Barzi, E
Fehér, S
Rossi, L
Zlobin, A V
Self-Field Effects in Magneto-Thermal Instabilities for Nb-Sn Strands
title Self-Field Effects in Magneto-Thermal Instabilities for Nb-Sn Strands
title_full Self-Field Effects in Magneto-Thermal Instabilities for Nb-Sn Strands
title_fullStr Self-Field Effects in Magneto-Thermal Instabilities for Nb-Sn Strands
title_full_unstemmed Self-Field Effects in Magneto-Thermal Instabilities for Nb-Sn Strands
title_short Self-Field Effects in Magneto-Thermal Instabilities for Nb-Sn Strands
title_sort self-field effects in magneto-thermal instabilities for nb-sn strands
topic Accelerators and Storage Rings
url https://dx.doi.org/10.1109/TASC.2008.921899
http://cds.cern.ch/record/1116072
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