Development of superconducting networks for a large scale magnetic shield

The shielding capabilities of a multiringed disk were analyzed to design the shielding networks. The applicability to a large-scale shield was examined experimentally and four conclusions are drawn: (1) the multiringed shields show the highest performance when the diameter of the rings is half of that of the disks; (2) if the diameters of the rings are adequate, a multiringed shield can control the field distribution; (3) the shielding efficiency is almost independent of the external field and the field sweep rate when the shielding currents in the rings does not exceed the effective critical current; when the shielding current reaches the effective critical current, the efficiency decreases with increasing external field, and in this case, flux jumps are apt to occur; and (4) for a large-scale shielding network, the effective critical current of rings must be enlarged