Design Of N-2 Cooled Bi-2223 Hts Current Leads For Use In 0.4t Field For The Nhmfl Series-Connected Hybrid Magnet

The design of a pair of 20 kA nitrogen vapor cooled current leads for service in a 0.4 T background field for the NHMFL Series-Connected Hybrid Magnet has been completed. The leads are comprised of a nitrogen vapor cooled resistive section made from pierced copper sheet and a high-temperature superconducting section made with stacked and soldered Sumitomo Type G Bi-2223 tape. A detailed discussion of the HTS section design, including findings from an in-house critical current characterization effort, magnetic field on the tapes, current and temperature margins and protection considerations is presented.