Experimental realization of a hybrid trapped field magnet lens using a GdBaCuO magnetic lens and MgB2 bulk cylinder

A hybrid trapped field magnet lens (HTFML) is a promising device that is able to concentrate a magnetic field higher than the applied field continuously, even after removing an external field, which was conceptually proposed by the authors in 2018. This paper presents, for the first time, the experimental realization of the HTFML using a GdBaCuO magnetic lens and MgB2 trapped field magnet cylinder. A maximum concentrated magnetic field of B-c=3.55 T was achieved at the central bore of the HTFML after removing an applied field of B-app=2.0 T at T=20 K. For higher B-app, the B-c value was not enhanced because of a weakened lens effect due to magnetic flux penetration into the bulk GdBaCuO material comprising the lens. The enhancement of the trapped field using such an HTFML for the present experimental setup is discussed in detail.