Development of a multiple HTS current lead assembly for corrector magnets application

Vapor-cooled current leads used for transmitting power to superconducting power equipment such as the corrector magnets in the SSC spools can introduce a significant heat leak into the cryostat which results in cryogen boil-off. Replenishing the boil-off or refrigerating and liquefying the vapors associated with the cooling of these leads may constitute a significant portion of the operating cost and/or the capital investment of the power equipment. Theoretical studies and experiments have demonstrated that the heat leak introduced by a current lead can be significantly reduced by using ceramic high temperature superconductor (HTSC) as part of the conductor in the current leads. A HTSC reduces heat leak in a current lead by being superconducting in the temperature range below its critical temperature and by having a low temperature thermal conductivity which is generally orders of magnitude lower than the copper alloys commonly used as the current lead conductors. This combination reduces Joule heating and heat conduction, resulting in lower heat leak to the cryostat. To demonstrate the advantages and large scale application of this technology, Westinghouse Science ampersand Technology Center has continued its efforts in High Temperature Superconducting (HTS) current lead development. The efforts include qualification testing and selection of commercial sources of HTSC for current leads and the successful development of a 12 x 100 A multiple HTS current lead assembly prototype for SSC Corrector Element Power Lead application. The efforts on the design, fabrication and testing of the multiple HTS lead assembly is reported below