Field Dependence of the Critical Current and Its Relation to the Anisotropy of BSCCO Conductors and Coils

Abstract

The design of HTS magnets is often based on the properties of a number of short samples that are presumed to be representative of the conductor to be used. Variability in conductor properties and inhomogeneity in the magnetic field distribution within the magnets, coupled with conductor anisotropy, provide a significant challenge to accurately predict the field dependence of the magnet critical current. This work is based on measured superconducting properties of Bi-2212 and Bi-2223 conductors at 4.2 K in parallel and perpendicular magnetic fields up to 33 T. Properties of double pancake units and stacks, from the same or similar conductor batches, are presented, based on measurements at self-field and in applied co-axial background magnetic fields up to 19 T. Modeling of this data is based on short sample properties in perpendicular field; the average grain misalignment is used as the parameter to quantify the anisotropy. Correlations and discrepancies between the measured data and models based on short sample data are discussed for Bi-2212 and Bi-2223 conductors.

The Characteristics of Bi-2223/Ag Conductor for High Field Application

“…All data were obtained in increasing magnetic field up to 30 T at 4.2 K. The round symbols are the critical current in parallel magnetic field and rectangles are for perpendicular magnetic field. It is well known that the critical current highly depends on the external magnetic field as shown in figure. The deterioration of critical current was much larger in perpendicular magnetic field than parallel ones [2]- [5]. In each measurement, good consistency was shown in the results at wide range of magnetic field.…”

“…In HTS insert using Bi-2223/Ag conductor, the tapes in coil are usually exposed to strong magnetic field. The critical current of conductor was significantly affected by the external field [3]- [5]. Therefore, the anisotropy and deterioration of critical current should be investigated for designing magnet in advance.…”

Statistical analysis of the relationship between electrical transport and filament microstructure in multifilamentary Bi2Sr2CaCu2Ox/Ag/Ag–Mg round wires

“…practical limits of commercial NbTi and Nb 3 Sn wires. It is well established that two high-temperature superconductor (HTS) technologies, (RE)Ba 2 Cu 3 O 7−d (REBCO) coated conductors and Bi 2 Sr 2 CaCu 2 O x (Bi2212) round wires, have the potential to meet this demand, as they have demonstrated very high critical current densities (J c ) at very high magnetic field [1][2][3][4][5][6][7][8]. At present, REBCO conductor development has progressed such that the superconducting REBCO layer itself is well understood and highly engineered; the challenges for REBCO high-field magnets are elsewhere [9].…”

High strength oxide dispersion strengthened silver aluminum alloys optimized for Bi2Sr2CaCu2O8+xround wire

“…If the conductor is not adequately supported, the induced strain degrades the conductor critical current (I c ). Thus, a Bi2212 RW with improved strain sensitivity and increased elastic modulus and yield strength is needed for high magnetic field applications [6][7][8][9][10].…”