Detection of ¹H NMR signal in a trapped magnetic field of a compact tubular MgB₂ superconductor bulk

Abstract

We measured 1H nuclear magnetic resonance (NMR) spectra from silicon rubber in a magnetic field trapped by a compact tubular MgB2 superconductor bulk magnet (60 mm outer diameter, 40 mm inner diameter, and 60 mm height) which was magnetized by field-cooled magnetization from an applied field, B a p p , of 0.4778 T at 20 K. The sharpest 1H NMR spectrum of the resonant frequency, f R , of 20.314 MHz, which corresponded to a field strength of 0.4771 T, was observed at 1 mm below the center of the bore of the MgB2 tube. The homogeneity of the trapped field was within 100 ppm between z = −2 and +2 mm along the central z-axis, which was evaluated by the position-dependent f R . No change in the trapped field was observed for about 25 d, which corresponded to a decay rate of less than 0.1 ppb h−1. The obtained results suggest that the MgB2 bulk magnet is a promising candidate for a magnetic pole in an NMR apparatus.

A new MgB2 bulk ring fabrication technique for use in magnetic shielding or bench-top NMR systems

“…For NMR applications, it is vital that the B FC temporal stability is maximised to enable long term use without continual remagnetisation. Recent work by Takahashi et al [1] illustrated that cooling after the magnetisation significantly improves the magnetic field persistence. However, the B FC value explored in that work was substantially smaller than the absolute performance of their sample, potentially leading to an overestimation of the true persistence.…”

“…It is well established that HTS joints are a significant issue [3] which are particularly pertinent for NMR systems. In NMR, the magnetic field decay must in the range of parts per billion for real-world systems [4] which should be readily achievable with bulk superconductors [1,5].…”

“…MgB 2 is considered a promising alternative for specific applications due to its range of physical properties. Not only is MgB 2 light (2.4 g cm −3 ) and mechanically robust [1], but the base materials are cheap. While the critical superconducting temperature (∼39 K) is lower than (RE)BCO it still lies within the capability of single-stage cryocoolers making system design uncomplicated.…”

Enhancing Critical Current Density of Bulk MgB2 via Nanoscale Boron and Dy2O3 Doping

“…[ 1 ] MgB 2 can be fabricated in various forms such as bulks, tapes, wires, and films, and hence show great potential in large‐scale applications. Major applications comprise coils and magnets for magnetic resonance imaging (MRI), [ 2 ] nuclear magnetic resonance (NMR), [ 3 ] magnetic drug delivery (MDD), [ 4 ] fault current limiters (FCL's), [ 5 ] transportation (magnetic levitation train), [ 6 ] etc. The majority of the research on MgB 2 has been focused on improving the critical current density ( J c ) and upper critical field ( H c2 ).…”

Effect of boron precursor ultra-sonicated in hexane medium on the critical current density of sintered bulk MgB2

“…Irrespective of the moderate critical temperature (it can be cooled using liquid H2, Ne), the large coherence length allows grain boundaries to be effective flux pinning centers, supporting a high critical current density in polycrystalline bulks. Light weight makes the material attractive for space [2] and portable device applications [3], and the uniform/isotropic trapped field behavior [4] contributes to reliability in application in various fields. One of the issues of MgB2 is its moderate critical current density, which has been a hot research area since 2 decades.…”