Pulsed field magnetization of multiple bulks used as field pole of a high-temperature superconducting rotating machine

An array of three GdBa2Cu3O7-delta bulk high-temperature superconductors (HTS) that mimic the field pole of a high-power superconducting motor had been magnetized by pulsed field magnetization (PFM) while cooled by liquid nitrogen. The bulk array was magnetized by a passive PFM technique using three vortex-type coils placed over each individual bulk and connected in series. The trapped magnetic flux density distribution was comparable to the distribution obtained with more traditional quasi-static magnetization such as fieldcooling. This suggests that the use of PFM technique on arrays of HTS bulks is possible. PFM has also been performed using each coil individually, to magnetize each bulk sequentially. The magnetization sequences showed a maximum reduction of the peak trapped magnetic flux density of 12% due to the demagnetization effect of the magnetization sequence, while the trapped magnetization distribution was improved.