Enhanced critical currents in bi-2223/ag sheathed tapes by high energy proton irradiation.

Willis, J. O. ; Coulter, J. Y.

Technical Information Center Oak Ridge Tennessee

关键词: Irradiation;    Protons;    Critical current;    High temperature superconductors;    Defects;   

RP-ID  :  DE2001784311

学科分类：工程和技术（综合）

美国|英语

来源: National Technical Reports Library

【 摘 要 】

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 Jc 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 q T. At this defect density, the Jc at 75 K and 1 T perpendicular to the tape plane is almost 100 times larger than that an unirradiated tape. For higher proton doses, there is increasingly greater grain-boundary damage, lowering the self-field Jc 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 Jc 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.