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 ° apart and input and output leads are extracted 180 ° 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 .