Numerical evaluation of anisotropy of magnetization losses in superconducting wires with elliptic cross section

摘要

AC losses are numerically estimated in straight superconductors with an elliptic cross section exposed to a transverse magnetic field. It is assumed that the distribution of magnetic field in the superconductors is determined by Bean's critical state model, in which the critical current density is independent of the magnitude of local magnetic field. The penetration process of magnetic flux into the superconductors approximated as a group of fine rectangular bars is evaluated by means of the minimization of magnetic energy for the application of the external magnetic fields with arbitrary angles to their broadest face. By using the obtained penetration process, the AC losses are also calculated from the distribution of magnetic vector potential inside the superconductors. Furthermore, the compensation for the numerical results of AC losses enables us to obtain a universal loss property that is scarcely affected by the aspect ratio of cross section and the angle of external field.