Low resistance cabled conductors comprising superconducting ceramics

摘要

A cabled conductor is provided for use in a cryogenically cooled circuit including refrigeration having a predetermined operating temperature and efficiency. The conductor includes multiple conductor strands cabled about the longitudinal axis of the conductor at a preselected cabling period, each strand including a composite of superconducting ceramic in intimate contact with conductive matrix material. Each filament has high performance regions in which the filament material is well-textured with its preferred direction aligned perpendicular to the widest longitudinal cross-section of the conductor alternating with poorly superconducting regions which are at least about half the diameter of a filament in length and in which the superconducting ceramic filament is strained by transposition in excess of its critical strain limit. In the poorly superconducting regions, the conductive matrix material provides an alternate current path. The ratio of the average length of the poorly superconducting regions to the preselected cabling period is less than about (rho300e/rhooe)epsiE, where rhooe is the resistivity of the composite at the operating temperature; rho300e is the resistivity of the composite at 300 Kelvins; and epsi is the predetermined efficiency of the refrigeration means at its operating temperature. In the preferred embodiment, this ratio is less than 1:4, and preferably less than 1:20.