Stress dependence of the critical currents in neutron irradiated (RE)BCO coated conductors

TL;DR

This study investigates how neutron irradiation affects the critical current and stress sensitivity of different high-temperature superconductor coated conductors, revealing material-dependent changes relevant for fusion magnet applications.

Contribution

It provides new insights into the stress dependence of critical currents in irradiated (RE)BCO coated conductors, highlighting differences between GdBCO and YBCO materials.

Findings

GdBCO/IBAD conductors show significant change in Ic sensitivity after irradiation.

YBCO/RABiTS conductors exhibit nearly no change in Ic sensitivity post-irradiation.

Irradiation reduces Ic and Tc notably in GdBCO/IBAD conductors.

Abstract

The application of HTS coated conductors in future fusion or accelerator magnets is currently of increasing interest. High Lorentz forces and therefore high hoop stresses act on the conductors in large coils. The conductor is furthermore exposed to neutron radiation in fusion or accelerator magnets. The expected neutron fluence over the desired lifetime of such magnets can be simulated by irradiation experiments in a fission reactor. The coated conductors were characterized in the pristine state and after irradiation to the ITER design fluence. The sensitivity of the critical currents to applied stress was measured in liquid nitrogen. The cold part of the set-up was positioned between a rotatable split coil electro-magnet for assessing the Ic-anisotropy up to 1.4T under maximum Lorentz force configuration. The Ic-sensitivity to applied stress changed significantly in the GdBCO/IBADconductors after irradiation, whereas nearly no change was observed in the YBCO/RABiTS-conductor. Furthermore, Ic and Tc were strongly reduced in the GdBCO/IBAD-sample after irradiation. The angular dependence of Ic changed for both samples in different ways after the irradiation, but no change in the angular dependence was observed upon applying stress. The high neutron capture cross-section of Gd and the resulting strong reduction of Tc seem to be responsible for the different stress dependence of Ic in irradiated Gd-123 coated conductors.