Test results of a 10 kA current lead using Ag/Au stabilized Bi-2223 tapes

Abstract

In the frame of the European Fusion Technology Programme, the Forschungszentrum Karlsruhe and the CRPP Villigen are developing a 60 kA current lead for the ITER Toroidal Field Coils using High Temperature Superconductors. In part 2 of the task, two 10 kA HTS modules were ordered in the industry and one is being fabricated at the Forschungszentrum Karlsruhe using different conductor designs. One 10 kA current lead using Bi-2223 stripes stabilized by Ag/Au has been tested at CRPP Villigen. The conventional heat exchanger is cooled by 60 K helium gas whereas the HTS module is conduction cooled. The test covers the electrical and thermal steady state as well as the thermal transient behaviour after switching off the helium mass flow with respect to the temperature profile, the head load at 4.5 K, the minimum mass flow rate of 60 K helium, the critical current evaluation and the quench behaviour. Special feature of the test equipment is the use of small Hall probes to measure the current distribution during both the steady state condition and the current sharing regime. The paper describes the experimental results as well as the thermal and electrical models developed to explain the data.