Design, fabrication and test of the react and wind, Nb3Sn, LDX floating coil conductor

The Levitated Dipole Experiment (LDX) is a novel approach for studying magnetic confinement of a fusion plasma. In this approach, a superconducting ring coil is magnetically levitated for up to 8 hours a day in the center of a 5 meter diameter vacuum vessel. The levitated coil, with on-board helium supply, is called the floating coil (F-Coil). Although the maximum field at the coil is only 5.3 tesla, a react-and-wind Nb₃Sn conductor was selected because the relatively high critical temperature will enable the coil to remain levitated while it warms from 5 K to 10 K. Since prereacted Nb₃ Sn tape is no longer commercially available, a composite conductor was designed that contains an 18 strand Nb₃Sn Rutherford cable. The cable was reacted and then soldered into a structural copper channel that completes the conductor and also provides quench protection. The strain fabrication steps such as: soldering into the copper channel, spooling, and coil winding, to prevent degradation of the critical current. Measurements of strand and cable critical during state of the cable was continuously controlled currents are reported, as well as estimates fabrication, winding and operating strains on critical current