Trapping a magnetic field of 17.89 T in stacked coated conductors by suppression of flux jumps

We have successfully trapped a field of 17.89 T at 6.5 K at the center of a compact coated-conductor (CC) stacks (13×12×11.7 mm3) within 75 min by suppressing flux jumps. The CC stack consists of 200 sheets of EuBa2Cu3O7 CCs with BaHfO3 nanorods to increase the critical current density at high fields and low temperatures. To enhance thermomagnetic stability, the central 50 CCs are coated with 1 µm thick Pb with large specific heat at low temperatures. Numerical calculations based on the actual J c-H characteristics reproduces the trapped field quantitatively. New directions for achieving even higher trapped field at higher temperatures and making use of the trapped field are discussed.

A novel preform compaction method for fabricating high-performance Y–Ba–Cu–O single-grain bulk superconductor

A novel preform compaction method based on one new type of divisible mould was employed for fabricating single-grain YBCO bulk superconductor, which can complete the preform demoulding process through opening of the mould, rather than pushing the preform out in the regular mould. Thus it has natural superiority on eliminating macro-cracks, which has been proved by the sample surface morphology and the trapped field characterization. In addition, the divisible mould pressed sample exhibits higher levitation force and trapped field properties than the regular mould pressed samples, verifying the potentials of the divisible mould on improving the bulk performance. The optical micrograph results prove the superiority of the divisible mould on eliminating tiny cracks on sample surface. The processing facility and sample reliability brought by the divisible mould should also be emphasized, because the crushing and re-pressing of preform when it presents visible cracks can be omitted and the failed samples with surface cracks will no longer appear. Consequently, the experimental efficiency and stability are both enhanced.