Influence of high heat capacity substances doping on quench currents of fast ramped superconducting oval windings

The effect of high heat capacity substances doping on superconducting magnets ramp rate induced quench currents has been investigated for three oval windings. The windings were wound from Rutherford type cable (1.44 × 4.64 mm 2), made of 10 multifilamentary NbTi strands 0.85 mm dia. Before applicati...

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Bibliographic Details
Published in:Cryogenics (Guildford) 2006-04, Vol.46 (4), p.252-255
Main Authors: Alekseev, P.A., Boev, A.I., Keilin, V.E., Kovalev, I.A., Kozub, S.S., Kostrov, E.A., Kruglov, S.L., Lazukov, V.N., Sadikov, I.P., Shutova, D.I.
Format: Article
Language:eng ; rus
Subjects:
Rare-earth intermetallic compounds
Specific heat
Stability
Superconducting windings
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Summary:The effect of high heat capacity substances doping on superconducting magnets ramp rate induced quench currents has been investigated for three oval windings. The windings were wound from Rutherford type cable (1.44 × 4.64 mm 2), made of 10 multifilamentary NbTi strands 0.85 mm dia. Before application of electrical insulation and winding the cable was covered with epoxy resin with three different fillers: BN (boron nitride—a standard filler for preventing of epoxy cracking at low temperatures), and two rare-earth intermetallic compounds (HoCu 2 and CeCu 6). The specific heat of these compounds at liquid helium temperatures is extremely high. The volumetric fraction of these compounds was 2.9% of the total winding volume, corresponding to 4.5 times increase of averaged winding heat capacity for HoCu 2 and to 1.5 times increase for CeCu 6. At high ramp rates (∼4 kA/s, or ∼6.5 T/s) quench current of HoCu 2 doped winding was 35% higher than that for the BN doped one, while for CeCu 6 doped winding the quench current increase was 12%. Measured quench currents match values calculated with our theoretical model, in which whole doping substances enthalphy was taking into account. It indicates that the enhanced enthalphy is fully utilized in the used range of d B/d t.
ISSN:0011-2275
1879-2235
DOI:10.1016/j.cryogenics.2005.07.005