Bus design, development and test for the superconducting super collider

This paper reports that the power bus to be used in the super collider magnets must operate in supercritical helium at 4.35 K and about 4 atm. The bus is nominally 17 m in length, must accommodate large differential thermal contractions, and must be amenable to large quantity, cost effective production, installation and joining to adjacent magnets. It must be stable with respect to the largest credible disturbance and be protected in the event of a propagating normal region. The stability requirement can be satisfied effectively in supercritical helium by providing for transient heat transfer to helium locally as in an Internally Cooled Cabled Superconductor. Protection requires a sufficiently large cross-section of copper in parallel with the superconductor to carry the current while the magnet string is discharged. These requirements are satisfied in this design with super collider cable for the conductor located between, and soldered to, two copper braids. Variations in the energy margin and in the protection characteristics of the bus as a function of the braid dimensions and channel cooling characteristics are discussed