Magnets for Small‐Scale and Portable NMR

Introducing a new shimming method based on combination of axial and radial Halbach arrays to have a uniform flux density for a low-field portable MRI system

“…B /S and third: F ω = ω 7/4 /(S) where, Larmor frequency is ω and area of PM magnet is S (cm 2 ) [26]. Next, for magnet suitability and compactness of MRI, a figure of merit  (T/kg) has been defined ( = F B  (V S /V 2 )) [14]. The mass density of magnet is ρ and the volume of sample and magnet are V S and V, respectively.…”

“…(Please insert Figure 7 here) (Please insert Figure 8 here) (Please insert Figure 9 here) (Please insert Table 1 here) C. Regular polyhedron cross-section and radial shimming In [14], regular polyhedron PM was used and acceptable results were reported. For each hexagonal, side size = 57 mm, height = 50 mm, usable gap = 100 mm and directions of magnetic field density are shown in Fig.…”

“…Each ring includes 24 pcs cubic PM. In [14], very small hexagonal bar magnets were used for constructing Halbach magnet. In [15], Halbach magnet is produced from two nested continued rings.…”

Time-Domain NMR in Characterization of Liquid Fuels: A Mini-Review

“…The main features of TD-NMR devices are their variable designs and simple setups and the possibility of measuring both liquid and solid objects of nonlimited size. For example, there could be single-sided, two-poled, or Halbach magnet configurations. − The single-sided NMR system differs from the other ones by its use of a higher magnetic field gradient, which can cause a significant diffusion contribution to relaxation in the case of liquids . The main peculiarities of the TD-NMR method are that the measurements are made on a time scale mainly with the observation of relaxation processes.…”