Results of the Cold Powering Tests of the Demonstrators of HL-LHC SC-Links

High current MgB
₂
based transmission lines (called Superconducting Links) have been developed at CERN in the framework of the High-Luminosity upgrade of the Large Hadron Collider (HL-LHC). A Superconducting Link is composed of 80–140 m long MgB
₂
superconducting cables incorporated in a flexible cryostat. The cables, which are actively cooled by forced flow of 5 K to 17 K gaseous helium, will be used for the cold powering of the superconducting magnets of HL-LHC. Three demonstrators were built and tested at CERN, over the past two years, to assess the performance of SC Links operated in conditions similar to those in the HL-LHC machine. Investigations included cryogenic and electrical tests in nominal, transient and accidental conditions. The electro-magnetic cross talk among cables was measured with nominal ramp rates in the circuits as well as with provoked fast current discharges. In this paper the tests performed on the demonstrators are reported and discussed.