Temperature dependence of HTS magnetic shielding properties: Measurements on Pb-doped Bi-2223 hollow cylinders submitted to axial magnetic fields

Measurements of the magnetic shielding properties of Pb-doped Bi-2223 hollow cylinders submitted to an axial magnetic field have been carried out at several temperatures in the range 10 K - 95 K. The amplitude of the internal magnetic field was probed using a high sensitivity 3-axis Hall sensor. We have studied the dependence of the shielding factor (the ratio of the applied magnetic field over the internal magnetic field) with respect to the sweep rate of the applied field at several temperatures. The experimental results were compared to a 2-D modelling based on Brandt’s algorithm [1, 2] involving a non-linear E(J) relationship and a field-dependent critical current density Jc(B). We compared the penetration of the magnetic field into an open cylinders and a cylinder closed at one end. The spatial distribution of the shielding factor along the axis of both tubes has been measured. Results show that the shielding efficiency is reduced in the vicinity of the cylinder ends.

[1] Brandt, E., Phys. Rev. B, 1998, 58, 6506-6522
[2] Denis, S. et al., Supercond. Sci. Technol., 2007, 20, 418-427