Superconductive switch

Abstract

A superconducting switch is bifilarly wound with two cupro-nickel matrix superconductors. Three layers of the wire is wound, with each layer of windings wrapped with four wires in hand and input and output portions of the wires adjacent to one another. This configuration and relationship between adjacent wires is maintained throughout all the layers of the entire winding. The windings are started 180.degree. apart and input and output leads are extracted 180.degree. degrees apart. The switch also includes a core around which the wires and a heater are wound, a casing to enclose the core, heater and wire windings, and a solid epoxy body which fills substantially all of the voids in the switch. Switch leads are stabilized using a copper channel in which they are soldered to avoid quenching when they are subjected to a high current in a magnetic field, and the copper channel is surrounded and soldered to a copper braid. This construction results in a stable superconductive switch which is noninductive, has a high current carrying capacity and off resistance, and which reduces cryogen boil-off during charging and discharging of a high energy magnet circuit. The switch can also keep the magnetic field drifts of a magnet to less than 0.1 ppm/hour.