First integrated test of the superconducting magnet systems for the Levitated Dipole Experiment (LDX)

The Levitated Dipole Experiment (LDX) is an innovative approach to explore the magnetic confinement of a fusion plasma offering the possibility of an improved fusion power source. In this concept, a magnetic dipole (a superconducting solenoid) is magnetically levitated for several hours at the center of a 5 m diameter, 3 m tall vacuum chamber. The Floating coil (F-coil) is designed for a maximum field of 5.3 T. A Nb3Sn conductor was selected to operate the coil when it warms from an initial temperature of below 5 K up to about 10 K at the end of the experimental run. The Levitation coil (L-coil) made from high temperature superconductor electromagnetically supports the F-coil in the center of the plasma volume. There are no electric or cryogenic feeders serving the coil through the plasma because the F-coil must operate in a levitated position. The coil is cooled by retractable feeds and inductively charged/discharged in a lower charging station (CS). The NbTi charging coil (C-coil) surrounds the CS and induces the current in the F-coil. The L-coil and C-coil have each been independently tested. This paper describes the first integrated test of the F-coil and C-coil.