Transport AC Losses in Superconducting Cylinder with Critical Current Density Distribution Along Radius

The AC loss per cycle per unit length of a hard superconducting cylinder has been analytically calculated from the critical state model assuming several distributions of a radius dependent critical-current density. It is shown that the critical-current density dependence significantly influences the AC loss at high currents. With the increase of the non-uniformity, the distribution of a quadratic decrease of the critical-current density from the surface inwards is the most favourable to lower the loss at any value of ac currents compared to other distributions.