Coated conductor development: an assessment

This paper summarizes the current status of basic research related to the u nderstanding and development of coated conductor tapes for use in large sca le superconducting applications. It reports highlights of a workshop and di scussion meeting which dealt with many of the central issues associated wit h both thick film deposition methods and the defects that control the criti cal current densities. Topics included texture control in the metal substra te, smoothing the substrate surface before the grain aligned buffer layers are deposited, deposition methods for the buffer layers, deposition methods for high performance in the superconducting layer. The ionized beam-assist ed deposition (IBAD) method, and the rolling-assisted biaxially textured su bstrate (RABiTS) method were the primary approaches to texture control. Emp hasis was placed on the use of microscopic probes to study defects and grai n boundaries in order to develop a science base for the factors that determ ine the superconducting critical current of practical conductors. In all of the discussion, an effort was made to identify basic research that would l ead to a fundamental understanding of the mechanisms at work so that we can improve processing methods and enhance performance of the superconducting tape. (C) 1999 Elsevier Science B.V. All rights reserved.