Flux migration across a closed HTS ring caused by the interaction of the current in the ring and a permanent magnet

Abstract

By combining the Law of mass action, Arrhenius equation and the magnetic flux creep theory of Kim-Anderson, we proposed a model to depict the flux motion across a current-carrying high temperature superconductor (HTS) ring under an external magnetic field. In this model, the rate of flux motion is exponentially related to the thermal activation energy of trapped fluxes and the level of potential barriers in HTS material. The rate is also proportional to the number density of the flux lines enclosed by HTS ring. To qualitatively validate the rightness of the model, a test was carried out with a “double eye” shaped YBaCuO tape circuit and a permanent magnet at 77 K. The experimental results proved the validity of the model. This model may be helpful for understanding the flux relaxation in HTS loops under an external magnetic field and may account for the flux dynamics of HTS as well.