Resin-impregnated bulk YBCO current leads for Maglev

Recent advancement in the fabrication techniques has allowed the production of large grain bulk RE-Ba-Cu-O (RE: rare earth elements) superconductors with large critical current density. The current leads can be machined from such large disks. However, the stress produced by refrigeration or electromagnetic induction sometimes causes cracking. It is therefore essentially important to improve mechanical properties of bulk materials to enhance their current carrying capability. In this study, we report on a novel technique to dramatically improve the mechanical properties of the current lead made of bulk superconductors, in which epoxy resin is impregnated into the bulk materials. At 77 K, a large current of 1000 A could be passed along the RE-Ba-Cu-O current lead without the transition from superconducting to normal state. The heat generation was also found to be much smaller than the current lead employed in the present Maglev model, showing that bulk RE-Ba-Cu-O is promising for current lead applications for Maglev.