Irradiation effects for in situ Nb3Sn-Cu composite conductors

A series of high performance in situ Nb3Sn-Cu conductors have been studied to determine the detrimental effects of neutron irradiation on the upper critical field, the transition temperature and the critical current. For fluences up to 1 × 10¹⁸n/cm², there is essentially no degradation of any of the superconducting properties. At 7 × 10¹⁸n/cm², however, Tchas dropped to 13 K and at 10¹⁹neutrons n/cm²Tchas dropped to 9 K. The ratio of Hc2/Tcis essentially constant at 1.0 T/K for fluences out to 1.3 × 10¹⁹n/cm². The volume pinning force goes as (1-b)²for all samples indicating that shear in the flux line lattice controls Jceven for samples with Tcas low as 6 K.