Miniature permanent magnet for table‐top NMR

The multi‐infinity dipole magnet is a new design capable of generating a relatively high and homogeneous permanent magnetic field (0.1–3 Tesla and homogeneity 20 ppm for 3 mm) that is suitable for nuclear magnetic resonance (NMR) or electron spin resonance (ESR) studies of small volume chemical or biological samples. The theoretical design and practical aspects involved in the construction of a prototype tabletop NMR system (0.6 T and homogeneity of 10 ppm in a ellipsoidal region of 3 × 3 × 5 mm 3 ) are described. A simple NMR relaxation time experiment was performed on a water sample doped with 40 mM of CuSO 4 . This system in its current configuration is suitable for relaxation time studies of materials or for educational use. The introduction of shim coils would increase the homogeneity of the magnet by a factor of 100, allowing the system to be used as a portable NMR spectrometer. In addition the introduction of gradient coils between the poles would transform the spectrometer to a MRI portable system for tissue analysis or simple MR microimaging at fields up to 3 T.