[Formula Omitted] Hollow Wires and Cables Embedded in a Mg Alloy Matrix

• Published in: IEEE transactions on applied superconductivity 2013-06, Vol.23 (3), p.6200605
• Main Authors: Giunchi, G, Saglietti, L, Albisetti, A. Figini, Perini, E, Schiavone, C, Ripamonti, G, Uglietti, D, Bruzzone, P. L
• Format: Article
• Language: English
• Subjects: Superconductivity
• ISSN: 1051-8223; 1558-2515
• DOI: 10.1109/TASC.2012.2230671

The brittleness of the [Formula Omitted] wires prevents performing a cable architecture with very small bending radius, similar to NbTi Rutherford cables. Consequently, it is important to reduce the thickness of the superconducting materials in order to increase its bending strain limit. In this context, thin Ni sheathed [Formula Omitted] hollow wires, having wall thickness of the order of 20 [Formula Omitted] and length of the order of 100 m, have been produced by the Reactive Mg-Liquid Infiltration process (Mg-RLI). The latest hollow monofilament made by Mg-RLI shows very high transport properties, having an engineering critical current density at 4.2 K, 3 T of 730 [Formula Omitted]. In this wire the small thickness of the [Formula Omitted] corona allows a twisting with pass of the order of a few cm and fulfils the thermal stability criterion for [Formula Omitted]. We have demonstrated that cables made by such braided or twisted wires may be conveniently reinforced, by embedding the wires in a molten Mg bath, so that the Ni sheath is almost completely dissolved and the wires are clad by an eutectic Mg10%at Ni alloy. This alloyed matrix is structurally well connected to the [Formula Omitted] material, with minimal thermal and electrical resistance at the interface. A cable prototype based on this metallic composite has been prepared with 21 mono-core [Formula Omitted] wires, twisted around a central hole, which may be useful for cooling purposes. This cable design may be applied as current leads or in short bus-bars, for high current supply.