Evaluation of a 5 T REBCO Pancake Coil Magnet with IBAD/PLD Coated Conductors

REBa2Cu3Ox (REBCO, RE = rare earth) coated conductors are expected to show high performance for superconducting applications because of their high current density and high mechanical strength. Fujikura has developed REBCO coated conductor over 570 A/cm width at 77 K, self field with over 800 m length. In addition, we have succeeded in developing a 5 T cryocooled REBCO magnet with a stored energy of 426 kJ. The magnet is composed of 24 pancake coils and the total length of the REBCO coated conductors is approximately 7.2 km. It is important to validate the long-term operation test results of the REBCO magnets with larger diameters in order to use these conductors in practical superconducting applications. We confirmed that the REBCO magnet could be excited up to 5 T 16 months after the fabrication of the magnet. On the other hand, we have evaluated the 24-stacked pancake coil in liquid nitrogen before fabrication the 426 kJ magnet. The difference of the calculated critical current (Ic) and measured Ic of the stacked coil was 2%. We have confirmed that the calculated coil Ic was in good agreement with the measured coil Ic in liquid nitrogen.