Pulsed Magnetic Field Assisted Technique for Joining $\hbox {MgB}_{2}$ Conductors for Persistent Mode MRI Magnets

The commercial availability of long lengths of MgB₂ conductor with an increasingly attractive price-to-performance ratio encourages its use in cryogen-free magnetic resonance imaging magnets. For such a magnet operating in persistent mode, connections between MgB₂ wires must be completely superconducting to ensure long-term magnetic field stability. A new electromagnetically assisted technique for joining MgB₂ conductors is proposed. An electrically conducting tube is electromagnetically formed around the wires to provide mechanical coupling. Mg + 2B powder is placed inside this tube between the wire ends with exposed MgB₂ cores. Pulsed magnetic field compression of the tube densifies the joint powder, which is also redistributed into better contact with wire cores, and forms the tube to the shape of the joined wires. Cu powder has also been added into the Mg + 2B joint powder to minimize the reactive diffusion between Mg and Cu components. Finite element modeling of the deformation process will be presented, along with critical current measurements performed on a joint and on the individual wire for comparison. The applicability of this method for joining wires in reacted and unreacted form for magnet applications will be discussed.