The Influence of J_c(B) and n-Value on Magnetization Loss and Dynamic Loss in REBCO Coated Conductors

REBCO coated conductors (CCs) carry dc currents under ac magnetic fields in many high temperature superconducting (HTS) applications, such as field windings of rotating machines, flux pumps and persistent current switches. In such operating conditions, magnetization loss due to the shielding currents, and dynamic loss arising from the dynamic resistance in CCs, are critical issues which need to be taken into considerations for the machine design. In this work, magnetization loss and dynamic resistance/loss in a 4-mm-wide REBCO CC were calculated using the 2D H-formulation finite element method (FEM) based on the E-J power law of the CC. Constant J(c), and field-dependent J(c)(B) are used in the E-J power law. The influence of n-values on both loss behaviors is also studied when n-values vary from 10 to 100. Our results show that magnetization loss increases with increasing n-value at low magnetic fields while decreases at high magnetic fields. Such opposite n-dependence is attributed to the changing saturation region of the shielding currents when the current-reversal region shrinks. On the contrary, dynamic loss increases with increasing n-value due to the extended dc current flowing region. Furthermore, the high dc current level has a strong influence on the n-dependence of magnetization loss.