Izvorni znanstveni članak
Critical currents and vortex pinning in 235U doped Ag/Bi2223 tapes
Emil Babić
; Department of Physics, Faculty of Science, University of Zagreb, 10000 Zagreb, Croatia
Ivica Kušević
; Department of Physics, Faculty of Science, University of Zagreb, 10000 Zagreb, Croatia
Damien Marinaro
; Centre for Superconducting and Electronic Materials, University of Wollongong, Wollongong, NSW 2522, Australia
Shi Xue Dou
; Centre for Superconducting and Electronic Materials, University of Wollongong, Wollongong, NSW 2522, Australia
Sažetak
Systematic analysis of the transport critical current densities Jc at 77 K for 235Uoxide (UO2 · 2H2O) doped Ag-sheathed (Bi,Pb)2Sr2Ca2Cu3Ox tapes (Bi2223) irradiated with thermal neutrons is presented. Within the explored range of U-oxide concentrations (c ≤ 2 wt%) and neutron fluences (φ ≤ 6 · 1019 n/m2), the pinning of vortices in irradiated tapes increases approximately linearly with fission track density (proportional to cφ), as evidenced by progressively weaker magnetic field dependence of Jc on increasing cφ. Accordingly, the crossover field B∗ at which the pinning force density Fp reaches its maximum value Fp max = JcB∗ and the irreversibility field Birr(Fp → 0) increase approximately linearly with cφ. Therefore, Jc − B and Fp − B variations for all tapes with vortex pinning dominated by fission tracks show universal scaling behaviour with the scaling parameter B∗ (proportional to cφ). Taking into account the adverse effects of c and φ on Jc of our tapes, we estimate a maximum B∗ and Birr that can be reached in 235U-oxide doped Bi2223 tapes at 77 K.
Ključne riječi
Ag-sheathed Bi2223; 235U-oxide doping; U-oxide concentrations ≤ 2 wt%; thermal neutron irradiation; fluences (φ ≤ 6 · 1019 n/m2); critical current densities at 77 K; pinning of vortices; crossover field; irreversibility field; universal scaling behaviour
Hrčak ID:
301561
URI
Datum izdavanja:
1.10.2001.
Posjeta: 554 *