Development of a superconducting bulk magnet for NMR and MRI

[Display omitted] •A 4.74T superconducting bulk magnet for NMR and MRI was developed.•It has sufficient homogeneity for high-resolution NMR and MRI.•This magnet is promising for a compact MRI and NMR spectrometer. A superconducting bulk magnet composed of six vertically stacked annular single-domain c-axis-oriented Eu–Ba–Cu–O crystals was energized to 4.74T using a conventional superconducting magnet for high-resolution NMR spectroscopy. Shim coils, gradient coils, and radio frequency coils for high resolution NMR and MRI were installed in the 23mm-diameter room-temperature bore of the bulk magnet. A 6.9ppm peak-to-peak homogeneous region suitable for MRI was achieved in the central cylindrical region (6.2mm diameter, 9.1mm length) of the bulk magnet by using a single layer shim coil. A 21Hz spectral resolution that can be used for high resolution NMR spectroscopy was obtained in the central cylindrical region (1.3mm diameter, 4mm length) of the bulk magnet by using a multichannel shim coil. A clear 3D MR image dataset of a chemically fixed mouse fetus with (50μm)3 voxel resolution was obtained in 5.5h. We therefore concluded that the cryogen-free superconducting bulk magnet developed in this study is useful for high-resolution desktop NMR, MRI and mobile NMR device.