Evaluation of a 5T 2nd Generation High Temperature Superconducting Magnet with a 200-mm-diameter Room Temperature Bore

REBCO coated conductors are expected to show high performance in superconducting applications, because of their high mechanical strength and high current density in the magnetic field. However, more characteristics data of REBCO magnet with larger diameter are required in order to apply these conductors in practical superconducting applications.In this work, we have succeeded in developing a 5 T cryo-cooled high-temperature superconducting (HTS) magnet, which was composed of 24 pancake coils with an inner diameter of 260 mm, using REBCO coated conductors. The stored energy of the magnet was 426 kJ. The total length of the REBCO coated conductors was approximately 7.2 km. These conductors were fabricated by Fujikura Ltd. using ion-beam-assisted deposition (IBAD) and pulsed laser deposition (PLD) methods. All pancake coils were confirmed the V-I characteristics without degradation in liquid nitrogen before fabricating the magnet. The magnet was cooled down to 24 K by a GM (Gifford-McMahon) cryocooler after the fabrication. The magnet could excite up to 5.0 T in 60 minutes, successfully. Furthermore, we confirmed that 1% current reversal of the coil current could stabilize the axial central magnetic field drift of this magnet.