Suitability of coated conductors for fusion magnets in view of their radiation response

HTS coated conductors could replace Nb₃Sn wires in future fusion power plants, where the superconductors are exposed to neutron radiation. The maximum neutron fluence a superconductor can sustain is an important criterion for its suitability for fusion magnets. We report on the change of the superconducting properties in HTS RABiTS based coated conductors following high fluence irradiation (up to 3.3 · 10²² m⁻²) in a research reactor, which is significantly higher than previously reported. The transition temperature decreases as a function of fluence by up to 8 K and the critical current, I_c, heavily degrades when the magnetic field is applied parallel to the tape surface. The critical currents exhibit a maximum in their fluence dependence for the perpendicular field orientation, which shifts to lower fluences at higher temperatures. The same behavior is found for the fluence where I_c falls below that of the pristine tape. This limits the operation conditions to low temperatures under the expected lifetime fluences in future fusion magnets. (paper)