Measurement system for strain effect on Ic in coated conductor tapes at 77 K under magnetic field using a pair of permanent magnets

Abstract

In this study, in order to investigate the strain effect in the critical current, Ic of coated conductor (CC) tapes under magnetic field a newly devised measurement system using a pair of permanent magnets was constructed. The level of magnetic field applied could be controlled by the distance between magnets located in parallel. The distribution of magnetic field between the permanent magnets was checked using a hall probe sensor. External magnetic field was applied perpendicular to the CC tapes surface. Uniaxial tensile strain was applied to the tape by using devised loading frame mounted on a universal testing machine and the strain induced was measured by using a Nyilas type extensometer. Ic/Ic0–εt relation of the CC tape was first measured at self field. External magnetic field was then varied to investigate the dependency of critical current, Ic, and its effect on the reversible strain limit under uniaxial tension. Finally, the transport property characteristic of SmBCO CC tapes under magnetic field with uniaxial tension using permanent magnet is compared to the case using superconducting magnet.