Trapped field properties of a concentric-circled MgB sub(2) bulk composite magnetized by pulsed field and field cooling

We investigated the trapped field properties of the concentric-circled MgB sub(2) bulk composite disk by pulsed field magnetization (PFM), which consists of 36 MgB sub(2) thin rings for both surfaces of the disk and a small MgB sub(2) central cylinder in the stainless steel disk. MgB sub(2) parts were fabricated by a reactive Mg-liquid infiltration (Mg-RLI) method. The trapped field profile just above the composite surface was very concentric circled, which suggested that the superconducting current flows along the azimuthal direction in the MgB sub(2) rings and the cylinder independently, even though the magnetic flux dynamically moves in the composite during PFM. The trapped field properties by PFM were reproduced qualitatively by the numerical simulation using the critical current density J sub(c)(B) of the MgB sub(2) parts estimated by the trapped field B sub(z) by the field-cooled magnetization (FCM). The composite disk is a promising candidate to realize the MgB sub(2) bulk magnet with concentric-circled trapped field distribution magnetized by PFM.