Simulation study for magnetic levitation in pure water exploiting the ultra-high magnetic field gradient product of a hybrid trapped field magnet lens (HTFML)

Abstract

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. In this study, we propose a new additional advantage of the HTFML, which could be applicable for magnetic levitation and separation. The HTFML device consisting of a GdBaCuO bulk cylinder and a GdBaCuO magnetic lens, after the magnetization process from an applied field, Bapp = 10 T, can generate a maximum trapped field, Bc = 11.4 T, as well as an ultra-high magnetic field gradient product, Bz⋅dBz/dz, over ±3000 T2/m at Ts = 20 K, which is higher than that of existing superconducting magnets and large-scale hybrid magnets. Through detailed numerical simulations, the HTFML device is considered for the magnetic separation of a mixture of precious metal particles (Pt, Au, Ag, and Cu) dispersed in pure water, by exploiting the magneto-Archimedes effect. The HTFML can be realized as a compact and mobile desktop-type superconducting bulk magnet system, and there are a wide range of potential industrial applications, such as in the food and medical industries.