Investigations On Magnetostriction Of Inhomogeneous High-Temperature Superconducting Materials And Structures

There are many defects in the structure of the non-ideal type II superconductor, such as micro cracks, impurities, etc., and these defects often make the high temperature superconductors(HTSs) showing the material aspects of the inhomogeneity and anisotropy. At the same time, in order to satisfy the demand of superconducting microwave devices, people often make HTSs as thin film. Based on the finite element method, the thesis focused on the magnetostriction of the inhomogeneous HTSs and the superconductor-substrate system. The applied magnetic field is parallel to the direction of elastic modulus. The main contents are as follows:Firstly, using the Kim critical state model, we introduce inhomogeneous coefficient of elastic modulus to study the magnetostriction of inhomogeneous HTSs. The influence of inhomogeneity of the elastic modulus, the critical current density, the amplitude and frequency of the applied magnetic field on the magnetostriction were studied. The numerical results show that the magnetostriction increases as inhomogeneous coefficient of elastic modulus increases. Similarly, when the critical current density, the amplitude and frequency of applied magnetic field increase, the magnetostriction increases.Secondly, the effects of interfacial continuities of superconductor-substrate system on the magnetostriction are studied. The continuities of the interface, the critical current density and the amplitude of the applied magnetic field have an obvious influence on the magnetostriction of the HTS. The effect of frequency of the applied magnetic field is not obvious on the magnetostriction.The thesis studied the magnetostriction of the inhomogeneity HTSs and the superconductor-substrate system. We established a magnetic-mechanical coupled model for the continuous transition of interface of the inhomogeneity HTSs. This model will provide a research approach to the interface problem of inhomogeneity HTSs.