Split pulsed magnet combining high peak central magnetic field and long rise time for pulsed field magnetization of high temperature superconductors

Abstract

Split pulsed magnets are widely employed in high temperature superconducting (HTS) motor armature winding as magnetizing coils to implement in-situ pulsed field magnetization (PFM) for HTS field pole magnets. We have designed and developed a compact and portable split pulsed magnet, that balances a peak central magnetic field of nearly 7 T and a rise time of 24 ms, making it particularly suitable for PFM of HTS materials at lower temperatures. Single and two-step PFM experiments of HTS GdBa ₂Cu₃O${}_{7-\delta }$ (GdBCO) bulk in different temperature ranges are conducted and the maximum trapped fields $B_t$ are observed to be $>3$ T in the 40–50 K temperature range and nearly 4 T at 30 K in a 30 mm diameter GdBCO bulk. The trapped field results validate the excellent PFM ability of this designed split pulsed magnet and indicate a high trapped field (close to 4 T) can also be obtained in a coreless double armature. Moreover, multi-physical field responses of the split pulsed magnet during discharge are analyzed by a 3D field-circuit coupling model, which manifests that the split pulsed magnet is in a stable and safe operating state even under the highest charge voltage. Finally, this study may provide a novel clue for the development of coreless HTS bulk motors and suggest that HTS coreless motors can maintain a high air gap magnetic field while avoiding losses and thrust or torque fluctuations caused by iron core saturation under high magnetic fields.