Real-time stress evolution in a high temperature superconducting thin film caused by a pulse magnetic field

The high temperature superconducting YBa2Cu3O7 − x films are widely used in various classes of microwave devices and these structures often undergo pulse magnetic field in applications. The stress behavior is of relevance to understand the mechanical response and important for assessing the safety of these superconducting structures. In this paper, we construct a theoretic model to analyze the stress behavior of a superconducting thin film-substrate system under a pulse loading (magnetic field), which is different with the well-known theoretic framework based on the Stoney formula. In the case of radial symmetry, the relationship between the stress of thin film and the electromagnetic body force is derived analytically. When a pulse loading is exerted on this film-substrate system, an analytical expression of stress dependent on the film curvature is presented, which can be considered as the foundation for the further experimental measurement. Moreover, we extend the coherent gradient sensor to kinetic measurement of the full field curvature. Using the presented model and the experimental technique, the full field stress and its evolution with time of a superconducting thin film-substrate system under a pulse magnetic field are obtained.