Numerical modelling of HTS response to magnetic field in perpendicular geometry

Understanding the static and dynamic magnetic behaviour of High Temperature Superconductors (HTS) has significantly progressed thanks to the development of space- and time-resolved experimental techniques. Among them, Magneto-Optical Imaging (MOI) stands out as a non-destructive method capable of providing quantitative information on local magnetic flux distributions with micrometer-scale resolution. In this work, we investigate the magnetic response of high-quality 𝑌 𝐵𝑎2𝐶𝑢3𝑂7−𝑥 thin films deposited on single crystal substrates (YSZ). MOI measurements were performed at different temperatures, in perpendicular geometry, i.e., with the applied field directed perpendicular to the HTS film. The MOI technique enables the direct reconstruction of the spatial distribution of supercurrent density and its dependence on the local magnetic flux density and temperature. To complement and interpret experimental observations, we developed numerical simulations based on an H-𝜙 formulation in the FEM software COMSOL Multiphysics. This approach qualitatively captures the electrodynamic behaviour of the HTS film, including field penetration and current redistribution during applied field ramps. The agreement between simulated and measured magnetic field profiles is promising for the predictive capabilities of the numerical framework. The combined experimental and numerical analysis demonstrates that the model provides a reliable tool for investigating current limiting mechanisms, assessing sample inhomogeneities, and understanding the influence of microscopic defects, on the electromagnetic performance of HTS films. This achievement is also instrumental for predicting the behaviour of HTS tapes in high-field magnet designs