Coated conductor development: an assessment

This paper summarizes the current status of basic research related to the understanding and development of coated conductor tapes for use in large scale superconducting applications. It reports highlights of a workshop and discussion meeting which dealt with many of the central issues associated with both thick film deposition methods and the defects that control the critical current densities. Topics included texture control in the metal substrate, 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-assisted deposition (IBAD) method, and the rolling-assisted biaxially textured substrate (RABiTS) method were the primary approaches to texture control. Emphasis was placed on the use of microscopic probes to study defects and grain boundaries in order to develop a science base for the factors that determine the superconducting critical current of practical conductors. In all of the discussion, an effort was made to identify basic research that would lead 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.