Numerical Analysis of Dynamic Resistance and Total Loss in REBCO-coated Conductors at Low Temperature under High Perpendicular AC Magnetic Fields

In several applications of high-temperature superconductors (HTS), a REBCO-coated conductor (CC) carries a DC current under varying magnetic fields. This generates AC loss which can be an important factor to consider in the thermal design of the application. In this work, the dynamic resistance (Rdyn), and total loss in a 4 mm wide Superpower REBCO CC are numerically investigated for AC perpendicular magnetic fields ( B m) up to 1 T and temperatures ranging from 30 K to 50 K. For I dc / I c0 > 0.1 (where Idc is the DC current level and I c0 is the self-field critical current of the conductor), either of the previously developed equations, the non-linear or the simple linear expression for determining B th (threshold magnetic field), can be used to predict R dyn . Finite dynamic loss is observed even below the B th points due to the emergence of resistance. The resistance arises from the superposition of subcritical shielding and transport currents which introduces a finite electric field in the CC. The total loss at higher fields decreases as the temperature increases from 30 K to 50 K for all current values, except for I dc / I c0 = 0.9. A lift-off in the total loss is evident for fields around 1 T for all temperatures investigated.