Electro-Magnetic Performance of MgB2 Cables for the High Current Transmission Lines at CERN

Abstract

Intense R&D work is ongoing at CERN in the framework of the High Luminosity LHC (HL-LHC) upgrade for the development of high current transmission lines, known as Superconducting Links (SC Links). The SC Link is an assembly of cables made from reacted MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> round wire. There are three different cable configurations, each formed from MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> cables rated at different currents of up to 7 kA. Considering the different layouts, a compromise between the cabling parameters and the properties of the reacted MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> wires is essential to ensure the operational and functional requirements of the cables after the cabling process. In the present paper we report on the electromagnetic characterization of the three MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> cables: 2 × 3 kA, 3 kA, and 7 kA. The cabling parameters were defined to fulfil the electromechanical characteristics of the reacted wires. The cabling process was experimentally assessed and its effect on the electrical performance of the cables was evaluated at 4.3 K. The validation of the electrical performance was performed by means of critical current measurements of short cables (2 m) in the FRESCA test facility at CERN. Finally, good agreement was found between the measured and the expected electrical performance of the MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> cables.