Studies of flux pinning by proton-induced fission tracks in multifilamentary tapes of (Bi,Pb)2Sr2Ca2Cu3O10/Ag superconductors

The effects of proton-induced linear defects on the dissipationless flow of current in multifilamentary Ag-sheathed tapes of (Bi,Pb)2Sr2Ca2Cu3O10 superconductors in the temperature range of 55–77 K are reported. Randomly oriented columnar defects of estimated areal density 5×1010/cm2 produced by 800 MeV proton-induced fission fragments provide substantial enhancement of critical currents of these tapes. Furthermore, these defects are more isotropic flux pinning centers than high-energy heavy ion irradiation-induced columnar defects. However, there is a tradeoff between enhanced pinning and the deleterious effects of radiation damage at higher proton fluences. It is shown that some of the global damage caused by the products of fission can be repaired by a suitable heat treatment of the samples.