Test Results and Analysis of a 2.9 T No-Insulation REBCO Dipole Magnet at 4.2 K

Dipole magnets with higher magnetic fields can contribute to further improving the performance of future accelerators. Using high-temperature superconducting (HTS) materials and no-insulation (NI) winding techniques is a potential approach for increasing the magnetic field of dipole magnets. The screening current effect in REBCO coated conductors and the characteristics of NI coils may influence the field magnitude and field quality of dipole magnets. To address these challenges, we developed a block-type REBCO dipole magnet consisting of six NI coils. The magnet was tested at 4.2 K in liquid helium, with multipole components measured using rotating Printed Circuit Board (PCB) coils. During the test, the maximum magnetic field was 2.90 T. The measured central magnetic field showed good agreement with calculations considering the screening current effect. The measured multipole components at 140 A, 210 A, and 250 A indicate that the asymmetry of the magnet increased during the test. The current source was turned off automatically at 251.1 A, resulting in the sudden discharge of the magnet. The measured voltages and magnetic fields after the sudden discharge are discussed.