Trapped field magnets of high-T-c superconductors

To develop trapped field magnets with YBCO bulks at and below 77 K, a serie s of trapped field magnets have been developed and tested. With two Phi 26 mm x 10 mm YBCO bulks, a trapped field magnet of 7.09 T at 29.8 K with low creep has been achieved. Cracks occurr when 10 T magnetic field is applied to charge this magnet. With two Phi 16 mm x 10 mm YBCO bulks, a trapped fie ld magnet of 7.02 T at 12.8 K has been achieved. Creep behavior of trapped field magnets at low temperatures are also investigated. When the trapped f ield is much lower than critical field, almost no creep was observed in our experiments.