Development of high temperature superconductor current leads for 70 kA

The Forschungszentrum Karlsruhe (FZK) and the Centre de Recherches en Physique des Plasmas (CRPP) are working on a joint development program to construct and test a 70 kA current lead using High Temperature Superconductors (HTS) for the Toroidal Field (TF) coil system of the International Thermonuclear Experimental Reactor, ITER-FEAT. This program follows the development program of an HTS current lead in the 20 kA range which was successfully completed in 2000. The HTS part of the current lead will be manufactured in industry whereas the construction of the heat exchanger and the final assembly will be done in the laboratory. The HTS current lead will be tested in the TOSKA facility of FZK which has the boundary conditions for the cryogenic and high current equipment. In this paper, the results of comparative studies on HTS current leads fabricated and tested by different laboratories and in industry will be summarized. The extrapolation of the present designs to 70 kA will be done using Bi-2223 tape material as a favored material.