Thermal optimum analyses and mechanical design of 10-kA, vapor-cooled power leads for SSC superconducting magnet tests at MTL

Spiral-fan, 10-kA, helium vapor-cooled power leads have been designed for Superconducting Super Collider superconducting magnet tests at the Magnet Test Laboratory. To thermally optimize the parameters of the power leads, the lead diameters, which minimize the Carnot work for several different lengths, two different fin geometries, and two RRR values of the lead materials were determined. The cryogenic refrigeration and liquefaction loads for supporting the leads have also been calculated. The optimum operational condition with different currents is discussed. An improved mechanical design of the 10-kA power leads was undertaken, with careful consideration of the cryogenic and mechanical performance. In the design, a new thermal barrier device to reduce heat conduction from the vacuum and gas seal area was used. Therefore, the electric insulation assembly, which isolates the ground potential parts of the lead from the high-power parts, was moved into a warm region to prevent vacuum and helium leakage in the O-ring seals due to transient cold temperature. The instrumentation for testing the power leads is also discussed.<>