Single pulsed field magnetization for a Gd–Ba–Cu–O high-temperature superconductor large bulk with a diameter of 140 mm

For practical machine application of high-temperature superconductor (HTS) bulk magnet, a pulsed field magnetization (PFM) using small-sized magnetization coils is quite essential. HTS bulk with a diameter of 60 mm has been magnetized successfully and has made the tested axial-type motor to be stable operation by using a couple of vortex-type armature coils. In the present study we report the pulsed magnetization of HTS bulk with a diameter of 140 mm. The crystallization of such large bulk tends to be inhomogeneous around the periphery. For the sample of GdBa2Cu3Oy−δ with 140 mm in diameter and 20 mm thickness, new split-type magnetizing coils of 100 and 140 mm in diameter were employed. When the PFM was performed with the coils of 100 mm in diameter, magnetic fluxes penetrate near the center rather than periphery. On the other hand, when we used the coils of 140 mm in diameter, magnetic flux penetrates the whole body, and magnetic flux tends to be immobile in the area. Thus, the PFM with the coils of 100 mm in diameter is effective to magnetization for near the center of HTS bulk. They are also effective to obtain a conical shape trapped flux density distribution. The PFM with the coils of 140 mm in diameter is effective to enhance the total magnetic flux.