Hysteresis losses in hollow superconductors

Flux penetration into a hollow superconducting filament in a time-varying transverse magnetic field is determined numerically. The magnetization of the filaments is calculated for field variations below and above the penetration field of the filament. The influence of the inner radius of the superconducting filament on the magnetization and the hysteresis losses in the filament is shown. The critical current density is taken to be constant during the external field cycle and depends within the superconducting filament on the local magnetic field, which is the sum of the externally applied field and the field induced by the local screening currents. Calculations based on the theory presented here show good agreement with experimental results