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Previous studies suggest that there is a significant variation in both shape and physical properties from filament to filament in a multifilament superconducting Bi-2223/Ag tape. We are investigating this variation for a tape with a high critical current density (J/sub c/). For this study, we extracted all the filaments from a specially prepared high-quality tape having J/sub c/ (0 T, 77 K) = 45 kA/cm/sup 2/ with 19 disconnected filaments. By attaching current leads and voltage taps to the filaments, we are able to measure electrical properties on a scale of 200-300 /spl mu/m. The experiments show a large variation in filament properties. The conductivity of a filament at room temperature is proportional to its critical current density J/sub c/ at 77 K (self-field) and filaments with a higher transition temperature T/sub c/ do also show a higher J/sub c/. There is also a variation in the magnetic field behavior of the filaments. SEM pictures of the filaments also show large variations. The filaments from the center of the tape, which are thinner and have a larger aspect ratio (and thus a larger silver-filament interface), show better grain alignment and fewer impurities than filaments from the edges.

Bi2Sr2Ca2Cu3Ox/Ag tape superconductors are used in applications like power cables and transformers. In these applications the superconductor is exposed to an alternating magnetic field that has different orientations with respect to the tape surface. In this paper the angle dependency of the magnetisation loss is considered from two points of view. First the measurement technique with pickup coils is analysed theoretically. Measured magnetisation loss in uni-directional magnetic field with various orientations and rotating magnetic field are compared. When the orientation is changed from perpendicular (0°) to parallel (90°) applied magnetic fields, the contribution of the perpendicular field component to the magnetisation loss is dominant up to 60°. A new model to describe the angle dependency of the magnetisation loss, based on the measured loss in perpendicular and parallel magnetic field is developed. Deviations between models and the measured loss are explained with the help of the theoretical analysis of the measurement technique. The new model is not only applicable for the magnetisation loss but also for other AC loss components.

A model to describe the angular dependence of the critical current of a superconducting Bi-2223/Ag tape is developed. The model is based on a Gaussian distribution of the misalignment angles of the grains. With this model it is possible to calculate the standard deviation of the misalignment angle of the grains from critical current measurements in a magnetic field oriented perpendicular and parallel to the tape plane. This enables us to determine the critical current behaviour for all orientations of the magnetic field. The theory is confirmed in an experimental way. The angular dependence of the critical current of the measured tape can be described at 77 K in the region between 0 and 200 mT within 3% by using a standard deviation of 7.8° in the misalignment angle.