AC losses in HTS bulk and their influence on trapped magnetic field

A trapped magnetic field in a bulk is decayed and even erased by the application of an AC external magnetic field whose amplitude is much smaller than the trapped magnetic field. In the paper an analytic model to describe behavior of the trapped magnetic field is proposed assuming that its decay is caused by thermal effect due to AC losses in the bulk. The proposed model well explains AC loss characteristics, temperature rise and the decay of the trapped magnetic field of the bulk. Based on the proposed model, methods to suppress the decay of the trapped are shown and the effectiveness of the methods is shown.