Enhanced critical currents in Bi-2223/Ag sheathed tapes by high energy proton irradiation

J. O. Willis
2002 AIP Conference Proceedings  
We irradiated Bi-2223/Ag sheathed tapes with high-energy protons, causing fission reactions with Bi and Pb nuclei and generating in situ splayed columnar defects in the superconductor core of the tapes. We find that the best 75 K critical-current density J c performance in an applied magnetic field B perpendicular to the tape plane is achieved at a matching field, for which the flux-quantum density equals the columnar-defect density, of about 1 T. At this defect density, the J c at 75 K and 1 T
more » ... J c at 75 K and 1 T perpendicular to the tape plane is almost 100 times larger than that for an unirradiated tape. For higher proton doses, there is increasingly greater grain-boundary damage, lowering the self-field J c and ultimately degrading the in-field performance. However, much of this damage can be repaired with a short anneal at 400°C. Decreasing the incident proton energy from 800 to 500 MeV has little effect on the enhanced J c performance and has beneficial side effects. Irradiation of a stack of tapes demonstrates the high penetration power and uniform generation of columnar defects throughout a substantial volume of material. The application of this technique to improved device performance will be discussed.
doi:10.1063/1.1472666 fatcat:6govpptqwvbwlo7k53tejxrb7y