Non-Destructive Testing of Each Layer in GdBCO IBAD-PLD Coated Conductor by Using a High-Speed Scanning Laser Observation System

Abstract

With the aim of clarifying the origin of local defects in coated conductors (CCs) and feeding back to the fabrication process, we have examined the distribution of defects in each layer of a CC which has Ag/GdBCO/CeO2/LaMnO3(LMO)/IBAD -MgO/Gd2Zr2O7(GZO)/Hastelloy structure by means of a high-speed scanning laser observation system. The system detects anomalies in height of the surface and reflectivity due to existence of local defects such as depressions, precipitates, scratches, dust, and inhomogeneous physical properties at the maximum speed of 100 m/h. Distribution of local defects in superconducting layer has been examined by means of various evaluation systems with a Hall sensor array, a SQUID gradiometer array, and magneto-optical imaging. By comparing the data of defects evaluated by these testing systems, we found one of the main origins of the delamination defects was the anomaly at the surface of the Hastelloy substrate. It is possible to decrease the number of times and kinds of evaluation processes for low cost CCs with a higher yield by finding the key point of evaluation in the process of CCs with the laser observation system.