Excess magnetization due to interfilamentary proximity coupling in NbTi multifilamentary wires
✍ Scribed by N. Harada; Y. Mawatari; O. Miura; Y. Tanaka; K. Yamafuji
- Publisher
- Elsevier Science
- Year
- 1991
- Tongue
- English
- Weight
- 1012 KB
- Volume
- 31
- Category
- Article
- ISSN
- 0011-2275
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✦ Synopsis
It is shown theoretically that the excess magnetization of a multifilamentary superconducting wire caused by interfilamentary proximity coupling, AMp, is proportional to the twist pitch of the wire,/. It is also shown that this theoretical prediction can be confirmed experimentally for Nb -Ti multifilamentary wires. The critical current density of the superconducting shielding current flowing through the matrix, which becomes a weak superconductor due to interfilamentary proximity coupling, is given by Jcp = Jo(B/Bc2p)-l4 × [ 1 -(B/Bc2p)] 1.4 with Jo m [cosh(dN/2~jN)] -2, where B is the magnetic flux density, and Bc2p, ~N and d N are the upper critical flux density, the effective coherence length and the width of the weakly superconducting matrix, respectively. It is concluded that AMp can be estimated quantitatively by measuring the I dependence of total magnetization, and also that the most effective method of decreasing AMp is to decrease ~N to the dirty limit.