9501272 Garland This project is a three-year program of experimental research directed at understanding the properties of weak coupling effects in superconductors, with an emphasis on dimensionality effects, vortex dynamics, and non-linear transport. Two categories of experiments are planned. The first involves measurements of interlayer coupling and dynamics of vortex lines and Jospphson vortices in layered high temperature superconductors. The second category involves transport and radio frequency spectral response measurements of inhomogeneous non-linear superconducting media, including measurements of two- dimensional granular composite films and of phase correlations and fluctuations in Josephson junction arrays. %%% This project is a two-part program of experimental basic research on the electronic properties of high temperature superconductors, and also on the properties of microcircuit arrays of superconducting tunnel junctions. In the first project, the research will explore the response of high temperature superconductors to magnetic fields, with the ultimate foal of explaining the underlying physical principles that determine their technical and scientific applicability. The second project will investigate microcircuits of superconducting tunnel junctions, in part to elucidate fundamental physical principles and in part to determine the potential usefulness in electronics applications that require extreme sensitivity. ***