Magnetic lens effect using Gd-Ba-Cu-O bulk superconductor in very high magnetic field

Abstract

We investigate the performance of a magnetic lens in very high magnetic fields exceeding 24 T. The magnetic lens is composed of Gd-Ba-Cu-O superconducting bulk materials. The unique configuration of the magnetic field amplifier, which consists of slits and electrical insulation in the bulk, allows the magnetic flux density to be further enhanced by a background magnet. In field cooling operation, the external magnetic field was varied ∼4 T from 24.2 to 28.3 T and a total magnetic flux density of 30.35 T was found at the center of the device with a background magnet. The magnetic lens additionally increased the magnetic flux density by 2.05 T due to the lens effect. However, it was also observed that the bulk was partially quenched when the external field was varied. This partial quench and recovery of the bulk magnet is considered to be one factor that limits the performance of the lens effect. Finally, we are able to generate a substantial magnetic flux density of 2 T under very high magnetic field because we can obtain such high-field without further electrical power.

Magnetic Energy Harvesting and Concentration at a Distance by Transformation Optics

“…For small applied field values as required for sensitive magnetic sensors, the behaviour of the real materials will be very close to the ideal case. For large applied fields, superconductors have been used to concentrate magnetic energy with standard procedures for applied fields up to several teslas in magnetic lenses [13], so the applicability of our device for large fields will be mainly determined by the saturation field of the ferromagnets, at which its permeability may decrease towards smaller values than needed.…”

Create a Uniform Static Magnetic Field Over 50 T in a Large Free Space Region

“…As shown in Fig. 2(c) and (d), if we apply a uniform background static magnetic field whose magnetic flux density is 1T (as a numerical example), the static magnetic field inside our device (free space) can be larger than 50T, which cannot be achieved by any traditional method [29,30]. The material parameters of our device are shown in Fig.…”

Optimized performance of an all-REBaCuO hybrid trapped field magnet lens (HTFML) with liquid nitrogen cooling

“…Ring-shaped bulk superconductors, that can produce uniform and high magnetic fields in their central bore, are a powerful candidate for compact cryogen-free nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) systems [5][6][7]. In addition, as a magnetic field concentrator, a magnetic lens made of bulk REBaCuO has been also developed [8][9][10][11][12][13][14]. When an external magnetic field is applied to the bulk magnetic lens in the superconducting state during the zero-field cooled magnetization (ZFCM) process, a shielding current is induced so as to prevent magnetic flux penetration into the bulk due to the so-called 'diamagnetic shielding effect'.…”