Development of a RE-Ba-Cu-O superconducting strong magnet [News from Japan]

Today, superconductivity technology that can realize zero electrical resistance and very strong magnetic field is attracting much attention. Many kinds of electric apparatus such as rotating machines and transformers are using a field magnet consisting of an iron core with a copper coil wound around the core, or a permanent rare earth magnet. However, the highest magnetic fields obtainable with these kinds of magnets are around 1 Tesla, which limits the performance, energy efficiency, and space utility of the electric machines. On the other hand, magnets using superconducting wires that are able to carry very high current densities easily generate magnetic fields over several Tesla. However, metal-based superconducting wires can exhibit superconducting behavior only at very low temperatures around 10 K, which requires complicated cooling apparatus and expensive operating costs. This in turn limits applications of superconducting wires and magnets to specific areas such as pure scientific research or medical diagnosis in the form of nuclear magnetic resonance or magnetic resonance imaging.