Magnetic field trapping in a tubular stack of coated conductors

Together with superconducting solenoids and bulk magnets, stacked coated conductors (CCs) represent a third type of magnet capable of generating a high magnetic field. For some practical applications, however, sample space is needed for the latter two types of magnets. In addition, not only the value of the trapped field but also the temporal stability and spatial distribution of the field are important in the hollow space at the center of such magnets. In the present study, 8.99 T is successfully trapped at the center of tubular stacked CCs by applying 9 T as an initial field in the field-cooling process at 6 K. Very weak relaxation of the trapped field is also realized 1 h after the field-trapping process by quickly decreasing the temperature right after the completion of field trapping. Excellent spatial homogeneity of the trapped field along the z-axis as good as 300 ppm has been achieved over 1 mm diameter of spherical volume around the center of the tubular CCs.