Investigation of Splice Resistances of High-Current MgB2 Cables Operated in Liquid and Helium Gas

High-current MgB2 cables are being developed for the superconducting Link project at CERN in the context of the high-luminosity upgrade of the Large Hadron Collider. These cables will be connected to the superconducting magnets by means of splices with the Nb-Ti Rutherford cables. Electrical splices are one of the challenges of the new powering system, due to the relatively high-resistance matrix of the MgB2 wires. In addition, operation in gaseous helium requires specific optimization. In this study, we report on measurements of electrical splices between MgB2 cables in helium gas, and between MgB2 and Nb-Ti cables in liquid helium. We also report on the reproducibility of the joints, in order to obtain statistically relevant information. Measurements of multiple splices of different lengths and configurations are performed and compared to results from numerical calculations validated against measurements of soldered joints between single MgB2 wires.