Non-uniformity of coated conductor tapes

• Published in: Superconductor science & technology Vol. 26; no. 11; pp. 115013 - 9
• Main Authors: Solovyov, Mykola, Pardo, Enric, Šouc, Ján, Gömöry, Fedor, Skarba, Michal, Konopka, Pavol, Pekar íková, Marcela, Janovec, Jozef
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.11.2013; Institute of Physics
• Subjects: Coating; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Conductors (devices); Critical current density; Critical currents; Cross-disciplinary physics: materials science; rheology; Degradation; Density; Domain effects, magnetization curves, and hysteresis; Exact sciences and technology; Magnetic properties and materials; Magnetization; Magnetization curves, magnetization reversal, hysteresis, barkhausen and related effects; Materials science; Physics; Properties of type I and type II superconductors; Reduction; Superconducting materials (excluding high-tc compounds); Superconducting tapes; Superconductivity; Superconductors; Surface treatments; Critical current density; Scanning electron microscopy; Patterning; Magnetization; Magnetic field effects; Non uniform distribution; Superconductors; Critical current; Spatial distribution; Coated conductor; Strip material; Microstructure; AC losses
• ISSN: 0953-2048; 1361-6668
• DOI: 10.1088/0953-2048/26/11/115013

Non-uniformity of superconductor properties, e.g. a critical current reduction close to the edge of a coated conductor (CC) tape could degrade its performance in some power applications. Reliable characterization of such non-uniformity and understanding of its mechanism requires investigation of the character and causes of degradation. In this paper spatial distribution of critical current density across the width of a CC tape is studied. Three different experimental methods allowing estimation of the local current density were utilized for this purpose: (i) magnetic field mapping above the tape through which a DC current is flowing, (ii) measurement of the critical current of separate strips prepared by patterning of the CC tape, and (iii) magnetization measurements of the pieces cut from various positions within the tape width. Very good agreement between the results obtained by these methods was found, showing a reduction of the critical current density at the tape edges with respect to its centre. Moreover, structural investigation by scanning electron microscopy revealed a correlation between the morphology and the critical current density across the tape width. Insertion of such real non-uniform distribution of critical current density into AC loss calculation resulted in a dramatic improvement in the agreement with experimental results.