[en] The author presents a review of new results concerning the superconducting state stability under nonstationary conditions. The author considers the effect of small perturbations of the temperature δT and the electric field δE. A general approach is presented to the problem of superconducting state stability in a multifilamentary composite wire carrying a time-dependent transport current I(t). An equation is derived, determining the current-carrying capacity of this wire, i.e., the maximum superconducting current, I_m. It is shown that I_m depends on the physical properties of the multifilamentary superconducting composite, the geometry of the multifilamentary area, the cooling conditions, and the transport current ramp rate I. The author considers a quench propagation in a multifilamentary composite wire carrying a time-dependent transport current I(t). Concentration is placed on the effect of current ramp rate I and the superconducting state instability on the normal zone propagation velocity v. An equation determining v in a multifilamentary composite wire as a function of I is presented

[en] Published in summary form only

No abstract available

[en] The industrial development of multifilamentary superconducting wires has in the past been essentially concentrated on the two cubic materials (NbTi and Nb/sub 3/Sn, which can be produced with continuous filaments. Progress on Nb/sub 3/Sn wires was obtained by substituting ternary additives (B > 14 T) or by using composite cores (Β = 10 - 12 T). J/sub c/ of Nb/sub 3/Sn wires has been found to vary quite strongly when applying axial and transverse stresses. More recently, monofilamentary wires of complex, noncubic phases as PbMo/sub 6/S/sub 8/ (rhombohedral) and YBa/sub 2/Cu/sub 3/O/sub 7/ (orthorhombic) have been prepared by powdermetallurgical processes. A brief review of the state of art in producing wires of the various systems is given, with a particular emphasis on the material aspect on the current carrying capacity

[en] Ag-sheathed SmFeAsO_0.7F_0.3-δ (Sm-1111) superconducting wires were prepared by a one-step solid state reaction at temperatures as low as 850-900 ⁰C, instead of commonly used temperatures of 1150-1250 ⁰C. The x-ray diffraction pattern of the as-sintered samples is well indexed on the basis of the tetragonal ZrCuSiAs-type structure. We characterized the transport critical current density J_c of the SmFeAsO_0.7F_0.3-δ wires in increasing and subsequently decreasing fields, by a resistive four-probe method. A transport J_c as high as ∼ 1300 A cm^-2 at 4.2 K and self-field has been observed for the first time in Sm-1111 type polycrystalline superconductors. The J_c also shows a rapid depression in small applied fields as well as a magnetic-history dependence, indicating weak-linked grain boundaries. The low-temperature synthesis method can be very beneficial for fabricating the RE-1111 iron oxypnictides in a convenient and safe way.

[en] Intramagnetics General Corporation was founded in 1971 as a spin-off from the General Electric Company (GE). IGC is a world leader in superconductivity technology and applications. The US Department of Energy called IGC the United States' top commercial source of low-temperature superconducting wire, and also noted the company's superior performance in high-temperature superconducting wire. This article discusses the products of the company and its present/future plans. Organizational and commercial information is also presented

No abstract available

[en] Elementary conductors constituted of a plurality of superconducting filaments in a metallic matrix are prepared and then twisted. Elementary conductors with a diameter between 0.05 and 0.25 mm without electric insulation are twisted after heating with a pitch of four time the diameter, finally the conductor is insulated

[en] Studies of high aspect ratio structures with widths/thicknesses in the nanometer range - nanowires - have revealed extremely interesting behaviour associated with their reduced dimensionality [Fasol, 1998]. Metal nanowires in particular show interesting magnetic, superconducting and magnetotransport properties, but because it is so difficult to prepare nanowires of the same material with different crystal textures in a controlled fashion, it has been extremely hard to study how the texture affects the physical properties of such nanowires. In this study, an electrochemical system, which allows Pb nanowires to be deposited in nanoporous polycarbonate membranes was fully developed. Superconducting Pb nanowires with diameter ∼50 nm were deposited by pulse electrodeposition. It was shown that the texture of Pb nanowires may be manipulated by varying the pulse potential, either polycrystalline or single-crystal. TEM studies have confirmed that the structure control method is very reproducible and reliable

[en] Published in summary form only