Design and testing of a pair of current leads using bismuth compound superconductor

The thermal behavior of current leads using an oxide superconductor for the low-temperature portion has been studied. Numerical calculations predict a reduction of the necessary coolant flow rate and refrigerator input power. A pair of current leads has been manufactured where the low-temperature portion consists of six sintered Bi compound cylindrical bars and the high-temperature portion consists of a Cu wire bundle. The lead, cooled by gaseous helium along its entire length, is 0.9 m long and designed to carry 1 kA. The leads have been tested in the same arrangement as practical applications. The helium flow rate necessary to hold thermal equilibrium was about 80% of that for conventional copper leads. The calculation shows that power consumption of the refrigerator needed to cool high-temperature superconductor current leads with an optimum cooling scheme will be about one-third of that for conventional current leads.<>