In-situ determination of the transformer core's magnetization characteristics on HT-7 superconducting Tokamak

As a complex physics system, the tokamak plasma is strongly coupled with external poloidal fields, which are defined by electromagnetic circuits. For the HT-7 device with an iron core, the transformer magnetization plays the most important role. With a reasonable two-dimensional magnetizing current filament model, the magnetization curve was numerically derived from in-situ external magnetic experimental data detected by flux loops and small pick-up coils. To solve the ill-posed inverse problem, singular value decomposition scheme and iterative procedures were used and proved to be effective. This provides a practical solution for in-situ determination of the transformer's magnetization characteristics. It paves the way for tokamak experiment prediction and plasma current profile reconstruction.