Pulse field magnetization of a ring-shaped bulk superconductor

We have studied the pulse field magnetization of a YBCO bulk superconducting ring. In the experiments a 6 ms pulse magnetic field was applied to a ring-shaped YBCO superconductor with a 46 mm outer diameter, 16 mm inner diameter and 15 mm height, which was cooled by liquid nitrogen (77 K). Then, trapped magnetic field profiles were measured with a Hall sensor. For example, a single 1.2 T pulse field generated a hollow profile of the trapped magnetic field. In addition, the finite element method was used to solve the coupled problem of thermal and electromagnetic fields, where the power-n model was adopted for the E-J (E is the electric field and J is the current density) relation in the superconductor. A comparison between the results of experiment and analysis has shown that n = 6 gave good agreement between them. We have also discussed the current density distribution, temperature distribution, etc.