The (RE)BCO (where RE = rare earth element such as Y, Nd, Sm, Gd, etc.) family of bulk, melt processed high temperature superconductors (HTS) is the subject of extensive world-wide developmental research. Remarkably, a trapped field of 17 T has been achieved at 29 K (Tomita and Murakami, Nature 421, 517, 2003) in an arrangement of research samples of YBCO, which is more than an order of magnitude greater than that available from permanent magnets (and, significantly, over 100 times the energy density). It is clear, therefore, that bulk HTS materials offer considerable potential for both improving the performance of existing devices that incorporate permanent magnets and for developing new, high field applications.
Research in the Bulk Superconductivity group aims both to enhance the fundamental performance of superconducting bulks and to tailor them for specific applications. The group has a strong history of attracting funding from a variety of sources and is currently supported by the Engineering and Physical Sciences Research Council and by the Boeing Corporation.
The group has developed a new practical growth route using a "generic seed". This has allowed us to produce Gd based (RE)BCO bulk material in larger diameters (see right) which can trap fields of up to 1 T. The quality of the sample shown is indicated by the smooth profile evident in the trapped field measurement.
The group has developed a number of innovative methods to enhance flux pinning in single grain bulk superconductors. This allows the bulk samples to support larger critical current densities and thus, ultimately, to trap higher magnetic fields. Superconducting bulk samples have potential for replacing conventional permanent magnets in existing devices, such as motors and generators, with considerably superior performance.