AC Loss Measurement of MgB2 Superconducting Coils Under Rotating Magnetic Field

In this paper, we propose a new AC loss measurement system for MgB
₂
superconducting (SC) coils under rotating magnetic field. An AC loss measurement system using a Halbach array permanent magnet rotor and a torque meter is developed. A rotating magnetic field of 0.15 T peak at a maximum of 100 Hz is applied to the MgB
₂
SC coils in the cryostat, and the AC loss is measured as the difference in mechanical input with and without the MgB
₂
SC coils in the cryostat. The measurement results with cooling at 20 K and 25 K show that the AC loss at 60 Hz reached almost 7 W/cm
³
. And the fact that the order of magnitude of the measured values is almost the same as that of the other groups shows that the proposed method can be used to measure AC loss of SC coils.