Speaker
Description
A Bi2212-based, high temperature superconductor has been developed in reinforced, rectangular wire forms, with up to 400 MPa stress tolerances and high current densities, making them suitable for use in transposed cables, coils and magnets that are problematic with wide HTS tapes, and that need to operate beyond the field and temperature limits of low temperature superconductors. Our program has recently established long length production capability for a rectangular form of this wire, that we are now applying to develop robust, transposed, HTS-wire based cables and compact, high-field coils employing a wind-and-react approach that is similar to what is used with Nb3Sn. We have designed, produced and tested wires with varied reinforcement levels in straight and coiled forms, with the results validating that usefully high critical current densities (Je’s) and strengthening are achieved with low cost materials, scalable processes, and a simple final reaction step. Based on these data, we have now designed a strong, Bi2212-based wire for boosting field from ~ 22T to ~ 30T as required in, for example, a 1.2 GHz NMR system, while enabling the coil to fit into the available volume, and providing it with the required stress tolerance, insulation, operating current and current density at 4K. We have produced test lengths of this wire into a variety of small-scale solenoidal coils with the objective of establishing the wire-related techniques required to build an NMR insert type of coil, including insulation, strengthening with non-magnetic reinforcement, layer winding with smooth layer transitions, as well as connection of current leads.
