Critical currents in neutron-irradiated high temperature superconductors

摘要

Due to their extremely large penetration range in solids, neutrons are well suited for the production of randomly distributed defects in high temperature superconductors (HTS). Fast neutrons produce roughly spherical "collision cascades", which in most cases consist of amorphous material with a diameter of approximately 5-6 nm. Alternatively, thermal neutrons can be used to create fission tracks, if the HTS is doped with uranium prior to processing. In this case, the fission products create randomly oriented extended columnar defects with a diameter of about 10 nm and lengths of up to 15 #mu#m. The flux pinning capability of these neutron-induced defects is remarkable and strongly depends on the "dimensionality" of the HTS.