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[en] Study of flux motion and resistance in the new superconductors is of interest both for achievement of usefully low resistance at usefully large current densities, and for conceptual understanding of the idealized resistive behavior in the zero current limit. Some analyses emphasize the collective aspects of the interacting flux lines, whether liquid, solid, crystalline, or glassy; others emphasize the pinning of individual flux lines to material inhomogeneities; still others emphasize percolative Josephson coupling between grains. An overview is given of these approaches, their interrelation, and the experimental evidence, plus some new results on flux motion in large SNS arrays, treated as a model system. (orig.)

[en] After a brief historical perspective on the motivation for study of inhomogeneous superconductors, the formulation of Ginzburg-Landau equations suitable for such systems is reviewed. Attention is given to the important role of boundary conditions on psi and hpsi at interfaces and to the connection with Josephson effect coupling between discrete elements, as in layered compounds and granular superconductors. Finally, the resistive properties of composite wire containing finite length superconducting filaments in a normal metal matrix are discussed in more detail, with emphasis on proximity effect coupling and on the critical behavior of resistance and maximum supercurrent near the percolation threshold

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[en] As the diameter of a superconducting wire is decreased to the order of the coherence length or less, the wire is no longer able to sustain the long range phase coherence and a non-zero resistance is measured. Based on the theory for quantum phase slips, we estimate that if the normal resistance of the wire is larger than 450 Ω per coherence length, the wire will stay resistive even at T<< T_c. On the other hand, the localization effects may be weakening the superconductivity in the smallest wires due to enhanced Coulomb repulsion as the one-dimensional limit is approached

[en] The initial results are reported of SQUID voltmeter measurements on Cu-alloy wires which contain elongated μm-scale inclusions of superconducting Nb. Below the transition temperature Tsub(c) of the Nb inclusions the wires have a temperature-dependent resistance. A simple model is developed employing percolation theory to explain this behavior. (author)

[en] This summary will begin with short remarks, trying to recall some of the spirit of the presentations of each of the speakers during the first day, with no attempt at detail or completeness, given the need for a 20:1 compression relative to the original talk. The author hopes these idiosyncratic recollections do not infuriate the speakers too much. Since the speakers on the second day presented such interlocking topics, he simply tries to present some sort of consensus report, to which he adds some comments of his own. The two talks preceding this Summary on the final day dealt with the prospects for applications; since he had no chance to attempt to prepare a proper report on these, he says only a few words about those presentations