High-current-density Rutherford MgB₂ cable sheathed by CuNi30 alloy

Abstract

The Rutherford-type MgB2 cable has been fabricated from twelve of 6-core strands prepared by internal magnesium diffusion (IMD) process with resistive CuNi30 outer sheath. The uniformity of individual strands of diameter 0.448 mm prior and after additional densification by rolling was studied by X-ray micro-tomography. Engineering current densities of cable samples were measured at 4.2 K and external fields between 4.0 T and 8.0 T and compared with available published data. Presented Rutherford cable has the highest engineering current density with Je = 104 Acm2measured at external field of 5.73 T. The bending tolerance of the cable shows the critical diameter of 60 mm and less gradual critical current degradation in comparison to similar cables fabricated of single-core strands. AC losses measurements of present cable have lower coupling losses in comparison to monolithic multicore IMD conductor. Obtained results are promising for high current density and low AC loss MgB2 superconducting cable suitable especially for motors or generators.

High temperature superconductors for commercial magnets

“…The critical magnetic field is anisotropic, and higher values, up to 40 T are reported in thin films when the magnetic field is parallel to the ab-plane, but this is not achievable in wires. MgB 2 wires [77][78][79][80][81] have a specific application range at magnetic fields below 3-4 T and temperatures up to about 30 K (figure 20) and are therefore considered for applications such as MRI, motors and generators, and transport cables.…”

High critical current properties of multi-filamentary MgB2 superconducting wires fabricated using an internal Mg diffusion method

“…Compared with PIT-MgB 2 wires, the superconducting layer of IMD-MgB 2 has a considerable denser phase and better grain connectivity, leading to a higher critical current density J c [14,15]. For example, Kovac et al prepared a Rutherford cable using 12 MgB 2 superconducting wires with a six-filament structure [16]. Although the MgB 2 filling factor was only 13.8%, its engineering critical current density J e was 3.6 times higher than that of PIT wire with 19.8% MgB 2 [16].…”

“…For example, Kovac et al prepared a Rutherford cable using 12 MgB 2 superconducting wires with a six-filament structure [16]. Although the MgB 2 filling factor was only 13.8%, its engineering critical current density J e was 3.6 times higher than that of PIT wire with 19.8% MgB 2 [16]. Moreover, the 100-meter-level IMD-MgB 2 wire also possessed a high transport J c of 1.2 × 10 5 A cm −2 at 4.2 K and 8 T [17].…”