n-Value Analysis of Position-Dependent Property Variability in Long-Length Coated Conductors

• Published in: IEEE transactions on applied superconductivity Vol. 21; no. 3; pp. 2988 - 2991
• Main Authors: Willis, J O, Coulter, J Y, Rupich, M W
• Format: Journal Article Conference Proceeding
• Language: English
• Published: New York, NY IEEE 01.06.2011; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Anisotropy; Applied sciences; Conductors; Correlation; Critical current; critical currents; current-voltage characteristic; Electric connection. Cables. Wiring; Electric potential; Electrical engineering. Electrical power engineering; Electromagnets; Exact sciences and technology; Feedback; High temperature superconductors; Length measurement; Magnetic fields; Quality assurance; Superconducting magnets; Superconductors; Temperature measurement; Various equipment and components; Wire; Wires; Performance evaluation; high temperature superconductors; Voltage current curve; Feedback regulation; critical currents; Coated material; Quality assurance; current-voltage characteristic; Critical current; Anisotropy; Feedback; Manufacturing process; Electrical conductor; Microstructure; Value analysis; Magnetic field; Power law; High temperature superconductor
• ISSN: 1051-8223; 1558-2515
• DOI: 10.1109/TASC.2010.2087372

We measure the current voltage ( I - V ) characteristics of high temperature superconductor coated conductors (HTS CCs) as a function of magnetic field, magnetic field angle, temperature, and position along multi-meter length practical wires. The critical current ( I c ) data are analyzed to determine conductor uniformity, for quality assurance, and for feedback to the manufacturing process when an off-normal process event has occurred. We report on an expansion of this analysis to include the behavior of the power law exponent ( n ) of the voltage-current relationship, V ~ In , as a function of magnetic field amplitude and angle, temperature, and position for long CCs. American Superconductor recently identified as of interest H ||ab plane I c variations observed in wires fabricated by the MOD/RABiTS process. These variations were confirmed by LANL to exist in a 13 m length of wire. We also found correlations between I c and n that are indicative of these position-dependent microstructural/pinning property variations. We describe the applicability of this new n -value analysis to improved understanding of practical conductor performance and performance variability.