Rutherford cable made of internal magnesium diffusion MgB₂ wires sheathed with Al-Al₂O₃ particulate metal matrix composite

Rutherford MgB₂ cable has been made from 12 single-core wires prepared via the internal magnesium diffusion process with a light outer sheath of Al-Al₂O₃ particulate metal matrix composite. Initially, critical currents of single-core wires with different diameters (between 1 mm and 0.465 mm) were measured. X-ray tomography was applied for the analysis of the uniformity of a Rutherford cable assembled of 0.465 mm strands. The obtained engineering current density at 4.2 K and 6. 5 T for the present cable (with only 9.6% of MgB₂) is ∼3.6 times higher in comparison with a similar cable fabricated via the powder-in-tube in situ process with 19.8% of MgB₂ phase. The strain tolerance of the cable by bending has shown a critical diameter of 70 mm. AC losses measured via the calibration-free method have shown apparently lower coupling losses for the cabled conductor. The obtained results are promising for future lightweight, mechanically flexible and low AC loss MgB₂ superconductors suitable especially for motors or generators. (paper)