[en] The current-carrying capability of superconducting wires is degraded by stress. Therefore electromechanical properties are one of the key feedback parameters needed for progress in conductor applications. In this work, uniaxial tensile stresses and bending stresses were applied to Fe /MgB₂ wires at room temperature, followed by measurement of critical current using a transport method at 4.2 K. Basic mechanical properties were calculated from the measured stress-strain characteristics. The irreversible tensile strain at which the critical current density of MgB₂ wire starts to degrade was found to be 0.5%. In addition, the degradation of I_c with decreasing bending diameters was found to be very rapid for wires that were deformed after the heat treatment that forms the MgB₂ compound, while not much degradation of I_c was found for wires that were bent before being annealed. SEM observations confirmed that cracks could be healed by post-annealing

[en] Melt-textured YBCO superconductors are capable of carrying higher current densities than comparable copper conductors, and can therefore be used in electromechanical devices requiring high power densities. The advantage of textured YBCO superconductors is most pronounced in large systems such as electromagnetic launchers for aircraft carriers. In general, an electromagnetic launcher consists of a series of stationary pulsed electromagnets (the primary), which attract and/or repel a carriage carrying one or more magnets (the secondary). Several possibilities exist for the incorporation of HTSs into EM launchers, with the most direct being upgrading the magnets in the secondary to melt-textured YBCO. A system was developed to study propulsive force in a coaxial-type launcher. Results from this study are presented and their implications for launcher development discussed. A second type of launcher was also studied, with a power supply integrated into the launcher primary, so that the primary serves as a superconducting magnetic energy storage system. A method of optimizing energy conversion in a system of this type has been found. The time dependence of the magnetic field in this type of launcher is presented

[en] There are several motivations for increasing the diameter of melt textured single domain discs. The maximum magnetic field produced by a trapped field magnet is proportional to the radius of the sample. Furthermore, the availability of trapped field magnets with large diameter could enable their use in applications that have traditionally been considered to require wound electromagnets, such as beam bending magnets for particle accelerators and electric propulsion. We have investigated the possibility of using large area epitaxial growth instead of the conventional point nucleation growth mechanism. This process involves the use of large Y123 seeds for the purpose of increasing the maximum achievable Y123 single domain size. The hot seeding technique using large Y-123 seeds was employed to seed Y-123 samples. Trapped field measurements indicate that single domain samples were indeed grown by this technique. Microstructural evaluation indicates that growth can be characterized by a rapid nucleation followed by the usual peritectic grain growth which occurs when large seeds are used. Critical temperature measurements show that no local T_c suppression occurs in the vicinity of the seed. This work supports the suggestion of using an iterative method for increasing the size of Y-123 single domains that can be grown

[en] Helical windings of Fe-sheathed MgB₂ wires with different dimensions were fabricated by a wind-and-react process. Wires with a cross-sectional area of 1 mm² and 20% superconductor core were made using the powder-in-tube (PIT) method and ultra-fine starting precursors. Very good grain connectivity as well as high core density was obtained by using this method. At 20 K and self-field, the critical current of a coil with an ID of 12 mm and 12 turns was 360 A, which is equivalent to a J_c of 1.8 x 10⁵ A cm^-2. At a 6 T external magnetic field and 4.2 K, a coil with an ID of 140 mm and 10 turns possessed a J_c of 1 x 10⁴ A cm^-2. These results are a step towards the application of MgB₂ wires in the temperature range of 20-30 K and high magnetic fields

[en] A sharp cube textured Ni overlayer on Cu substrates has been developed for the manufacturing of long-length RABiTS-based coated conductor tapes. Using a low-cost, non-vacuum and easily scalable technique of electroplating, smooth, crack-free and continuous Ni overlayers were deposited on cube textured Cu substrates without any intermediate layers. In addition, sharp cube textured Sm-doped CeO₂ buffer layers have been grown on the Ni-plated Cu substrates using pulsed laser deposition and found to exhibit in-plane and out-of-plane FWHM values of 6.50 deg. and 5.25 deg., respectively. This electroplating process promises an efficient route for manufacturing Cu-based HTS coated conductors