Metal-as-Insulation HTS Insert for Very-High-Field Magnet: A Test Report After Repair

This study is a sequel to our previous study on a 38 mm diameter cold bore metal-as-insulation (MI) HTS insert that reached 32.5 T in a 18 T background magnetic field. For refurbishing, 7 MI double-pancake (DP) coils were re-wound with used REBCO tapes to just replace the damaged HTS pieces by new ones at inner junctions. 2 DP coils were fully fabricated using new REBCO tapes. The new assembled insert was then tested under various background magnetic fields at 4.2 K. The key focuses of this paper are: 1) the damages in the DP coils; 2) their repair; 3) the characteristics resistance change of the insert; 4) the resistance value of each DP coil; 5) the maximum field of the HTS-resistive hybrid magnet; and 6) the field stability estimation of the hybrid by NMR characterization.