Realization of compact hybrid trapped field magnet above 10 T with 7 T applied field

In this paper, Takahashi et al reported a successful case to reach this goal with a hybrid trapped field magnet (i.e. inner lens and outer cylinder trapped field magnet). The inner lens were cooled from room temperature to about 20 K in zero field cooling followed by applied field (e.g. 7 T) that the flux density will be concentrated to above 10 T. And in the same time the outer trapped field magnet will be field cooled from room temperature to about 20 K in this above 10 T field.