Microstructure origin of hot spots in textured laser zone melting Bi-2212 monoliths
Abstract:Hot spots are one of the main limitations in the development of large-scale high-power applications with superconducting materials. The application of digital speckle interferometry to detect inhomogeneous heating on ceramic superconductors allows the determining of a hot spot location in these materials before any damage is caused to the material. The technique detects deformations that are induced in the material due to dilatation, attaining a resolution of 0.45 µm /fringe. In this paper this technique has been applied to analyse the heating generation in Bi-2212 superconducting monoliths at room temperature and in operation conditions. In the first case a homogeneous heating is obtained, leading to a parallel fringe pattern. In the second case, a situation with an inhomogeneous heating origin has been detected. Once the position of this hot spot is determined, microstructure studies have been performed to determine which defects are responsible for hot spot generation.
Document Type: Research Article
Publication date: November 1, 2005