EFFECTS OF NEUTRON-IRRADIATION ON THE CRI TICAL-TEMPERATURE AND CRITICAL-CURRENT OF NB-TUBE PROCESSED NB3AL MULTIFILAMENTARY WIRES

The superconducting critical temperature and the critical current of N b-tube processed Nb3Al multifilamentary wires irradiated at reactor am bient temperature have been measured as a function of neutron fluence up to 1.2X10(19)n/cm(2)(E>0.1 MeV). The critical temperature decreases monotonically with neutron fluence. The decreases of the critical tem perature relative to their unirradiated values are about 9% and 34% fo r fluences of 3.9X10(18)n/cm(2) and 1.2x10(19)n/cm(2), respectively. N eutron fluence dependence of the critical temperature for these Nb3Al wires is found to be almost similar to that for Nb3Al bulk samples. On the other hand, the critical current in a magnetic field of 8T remain s almost unchanged up to a fluence of 1.4x10(18)n/cm(2) and then repid ly decreases with increasing fluence. This peculiar dependence on neut ron fluence of the critical current may be attributed to extremely sma ll size of Nb3Al filaments from the viewpoint of the flux pinning. The critical currents decrease monotonically with applied tensile strain for both unirradiated and irradiated samples. The rate of decrease in the critical current with strain for irradiated samples tends to be sm aller than that for unirradiated samples.