Quasipermanent magnets of high temperature superconductor: Temperature dependence

Abstract

We report on persistent field in quasipermanent magnets of high temperature superconductors. Magnets composed of irradiated Y1+Ba2Cu3O7 trapped field Bt=1.52 T at 77 K and 1.9 T at lower temperature. However, the activation magnet limited Bt at lower temperature. We present data on Jc(H,T) for unirradiated materials, and calculate Bt at various T. Based upon data at 65 K we calculate Bt in unirradiated single grains at 20 K, and find that 5.2 T will be trapped for grain diameter d∼1.2 cm, and 7.9 T for d=2.3 cm. Irradiated grains will trap four times these values.