Trapped field properties of a concentric-circled MgB2 bulk composite magnetized by pulsed field and field cooling

Abstract

We investigated the trapped field properties of the concentric-circled MgB2 bulk composite disk by pulsed field magnetization (PFM), which consists of 36 MgB2 thin rings for both surfaces of the disk and a small MgB2 central cylinder in the stainless steel disk. MgB2 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 MgB2 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 Jc(B) of the MgB2 parts estimated by the trapped field Bz by the field-cooled magnetization (FCM). The composite disk is a promising candidate to realize the MgB2 bulk magnet with concentric-circled trapped field distribution magnetized by PFM.