Thermal Boundary Resistance in a High Temperature Thin-Film Superconductor underVarying Heat Flux

摘要

The thermal boundary resistance between a YBa2Cu3O7 thin film and an MgOsubstrate was measured under conditions of varying heat flux. Heat flux was varied in a manner to explore any hysteresis effects present. It was concluded that hysteresis effects are present and are most likely attributed to changes in the peeling or compressive stresses in the thin-film. The changes in the peeling stresses may not be fully relieved after cycling of the heat flux or may have caused microstructural changes near the interface resulting in changes in microscale heat transfer characteristics. Additionally, finite difference method were used to model the physical situation. It was found that boundary resistance values generated by the computer program were several orders of magnitude less than experimental value. It was concluded that finer meshes must be used in order to increase the accuracy of the results. It was recommended that the modeling be redone on a main frame computer using finite element methods.