Analysis of the E-J Curve of HTS Tapes Under DC and AC Magnetic Fields at 77 K

Abstract

The evaluation of the electrical characteristics of technical HTS tapes are of the key importance in determining the design and operational features of superconducting power apparatuses as well as to understand the external factors which affect the superconducting performance. In this work we report the systematic measurements of the electric field versus current density, relation of short samples for three commercial HTS tapes (BSCCO-2223 tapes, with and without steel reinforcement, and YBCO-coated conductor) at 77 K. In order to get sensitive and noiseless voltage signals the measurements were carried out with DC transport current and subjecting the broad surface tape to DC (0-300 mT) and AC (0-62 mT, 60 Hz) magnetic fields. The voltage is measured by a sensitive nanovoltmeter and the applied magnetic field is monitored by a Hall sensor placed on the tape broad surface. The comparison between the results obtained from the three tapes was done by fitting a power-law equation for currents in the vicinity of the critical current. For the current regime below the critical one a linear correlation of the electric field against the current density is observed. The BSCCO samples presented the same behavior, i.e., a decreasing of -index with the increasing DC and AC magnetic field strength. Under AC field the decreasing slope of -index is steeper as compared to DC field. The -index curve for the YBCO tape showed similar behavior for AC field, however under DC field in the 0-390 mT range exhibited a slight decreasing of the -index.

Critical current of a layered high-temperature superconductor with artificial pinning centers: the Monte Carlo simulation

“…It should be noted that radiation defects are not always nanosized but their size and shape depends on the energy of the irradiation particles [43]. The features of EJ curves similar to those obtained by us have also been reported in [44] for Bi-2223 tapes in DC magnetic field ∼100 mT. Similar features have been reported in [45] for GdBCO wires; however, the wires in [45] had a copper stabilizer layer.…”

“…Similar features have been reported in [45] for GdBCO wires; however, the wires in [45] had a copper stabilizer layer. The features observed in [44,45] can appear either due to the complex nature of pinning or due to the movement of vortex bundles and heating processes. Our results demonstrate that pinning itself can cause the features (instabilities) of the EJ curves.…”

Distribution of Current Density, Temperature, and Mechanical Deformation in YBCO Bulks Under Field-Cooling Magnetization

“…These values were chosen to reproduce the trend of the n-value as a function of magnetic flux density and temperature [16]- [18]. b) Thermal model: The thermal model which is coupled to the electromagnetic model through the dissipating term Q = σ ∂A/∂t 2 includes temperature-dependent material properties.…”

Design Aspects and Test of an Inductive Fault Current Limiter

“…On the other hand, inductive SFCLs require an iron core which make them relatively heavy but do not need current leads, require lesser amounts of superconductor and are robust against hotspot formation. A field test has carried out by ABB Company many years ago using HTS bulk cylinders [10], and only recently, due to the emergence of HTS tapes [11], [12], [13] and [14], several projects have been performed, either using first generation [15] or second generation tapes [16].…”