High temperature superconducting current leads for the Large Hadron Collider

The large hadron collider (LHC) will be equipped with about 8000 superconducting magnets. Some 3380 leads will feed the currents ranging from 60 to 13000 A. To reduce the heat inleak into the liquid helium, CERN aims to use high temperature superconducting material for leads having current ratings between 600 and 13000 A. Specifications have been written for 13000 A current leads, incorporating a high temperature superconducting section, for the main of the LHC, and contracts have been placed with several firms for the supply of prototypes for comparative testing. The leads used for feeding locally the 60 and 120 A dipole orbit correctors will be conventional conduction cooledmagnets resistive leads. An optimized lead of variable cross section has been tested, and an integral design has been initiated. This report describes the design status of the current leads for the LHC, emphasizing, for the different solutions, the principle of optimization and the choice of cooling methods. (8 refs).