Data di Pubblicazione:
2008
Citazione:
Self-field effects in magneto-thermal instabilities for Nb-Sn strands / B. Bordini, E. Barzi, S. Feher, L. Rossi, A.V. Zlobin. - In: IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY. - ISSN 1051-8223. - 18:2(2008), pp. 4493365.1309-4493365.1312. ((Intervento presentato al 20. convegno International Conference on Magnet Technology tenutosi a Philadelphia nel 2007.
Abstract:
Recent advancements in the critical current density (Jc) of Nb3Sn conductors, coupled with a large effective filament size, have drawn attention to the problem of magneto-thermal instabilities. At low magnetic fields, the quench current of such high Jc Nb3Sn 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 Nb3 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.
Tipologia IRIS:
01 - Articolo su periodico
Keywords:
instability; magnet; Nb3Sn; superconductor
Elenco autori:
B. Bordini, E. Barzi, S. Feher, L. Rossi, A.V. Zlobin
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