Characterization of superconducting wires by cone-beam micro-tomography

Commercial wires of Nb3Sn and MgB2 were inspected through X-ray cone-beam micro-tomography (μCT). Details of the architecture of the wires of different topologies were visualized. In the case of MgB2 wires this allowed to compare the geometrical perfection of the component elements between the wires with 18 and 7 superconducting sub-elements heat treated for different conditions. Defects such as 3D voids and interruption of the diffusion barriers were also visualized. High resolution 3D-μCT observations of the Nb3Sn wire architecture allowed also direct and non-invasive determination of the twist-pitch parameter. 3D tomography shows important advantages over 2D traditional microscopy methods.