Researchers from the RIKEN Center for Life Science Technologies and Chiba Univ. have developed a high-temperature superconducting wire with an ultrathin polyimide coating only 4 μm thick, more than 10 times thinner than the conventional insulation used for high-temperature superconducting wires. By drastically reducing the ratio of insulation to conductor in the wire, the research overcomes one of the key obstacles to the development of more compact superconducting coils for use in a new generation of medical and scientific devices.
Superconductivity is a phenomenon whereby at ultralow temperatures an electric current can travel through material with zero resistance. Coils made of superconducting wires are used as magnets in a variety of devices including MRI machines, NMR spectrometers and superconducting linear motor trains.
Conventional high-temperature superconducting wires used in such superconducting coils are roughly 100 to 150 μm thick, or roughly one tenth of a millimeter, of which half or more is taken up by insulating material. While needed in superconducting magnets to prevent short circuits, this insulating material impedes current density, requiring the coils to be very large.
Using the new technique, the researchers were able to create superconducting wires whose cross-sections contain only 10% insulation coating, a fivefold drop compared to conventional wires. This technique can be easily applicable to wires as long as several kilometers which are required for full scale superconducting devices. Magnetic coils created from the wires also achieve significant performance gains, including a doubling of magnetic strength and volume reduction of more than 80%.
The research was published in Physica C.