Fiber-reinforced-superconductors with high-elastic modulus and low thermal prestrain on Nb3Sn layers for high-field pulsed magnet

We have been developing a new type of Nb₃Sn superconductor, a fiber-reinforced-superconductor (FRS), to make an attempt at the application of high-field pulsed superconducting magnets. FRSs have high elastic modulus fibers such as tungsten so that the strain on superconducting layer caused by hoop stress can be reduced. Such high elastic modulus materials however, tend to have lower thermal expansion coefficient compared with Nb₃Sn. The resultant tensile prestrain on Nb₃Sn at liquid helium temperature brings about the degradation of superconducting characteristics. In this paper, it is shown that the strain characteristics of FRS can be largely improved by adopting a tungsten alloy, keeping high elastic modulus of pure tungsten