Proposed Method for the Verification of the LHC Bus Bar Splices during Commissioning at Cryogenic Conditions

The commissioning of the Large Hadron Collider at CERN includes the powering of about 1600 superconducting electrical circuits to currents ranging from 55Â A to 11.8 kA. A large number of splices (over 70'000) are present at the magnet interconnects, which can only be validated with current at cryogenic conditions. This paper discusses the thermal effects related to possible faulty splices during the powering of the circuits. The calculations of the quench and detection currents, as well as the hot spot temperatures, are described. The heat transfer model with the surrounding coolant and the current profiles inside the splices are presented. This study is completed with a sensitivity analysis on the hot spot temperature with respect to the model parameters. Finally, the implications with respect to the powering ramps and parameters to be applied during the first powering are discussed.