Modeling current percolation in granular superconductors

A grain growth model has been used to simulate the structure of a RABiTS coated conductor. By using this along with existing percolation modeling techniques, we describe the current carrying behavior of coated conductors considering both the grain boundaries and the grains. The effect of tape parameters such as length, width and grain size are studied, and the relative importance of crystallographic texture and granular pinning are discussed. We conclude that whilst grain boundaries still limit the performance of present RABiTS conductors measured at 77 K in self field, granular dissipation does have a role, and that this will become more significant in a large magnetic field.