Flexural properties of a MgB2 thin-film wire

Abstract Aiming to understand the bending characteristics of a MgB 2 thin-film wire and utilize the wire in the design of superconducting magnets, we examined the degradation of critical current density J c due to bending. Six short MgB 2 thin-film wires with a thickness of 1 μ m were prepared under the same deposition conditions. They were bent in different radii, and their J c were compared. The allowable bending radius at which J c does not degrade was 25.0 mm. As for MgB 2 thin-film wires, thickening the film effectively increases the engineering critical current density J e . On the basis of material mechanics, the allowable bending radius was estimated to be 25.5 mm when the film thickness increased to 10 μ m. The allowable bending radius of the MgB 2 thin-film wire is sufficiently smaller than the radius of a typical superconducting coil, so it is not considered to be a barrier to fabricating a coil with the wire.