Influence of the Distribution of the Properties of Permanent Magnets on the Field Homogeneity of Magnet Assemblies for Mobile NMR

We optimized the magnetic field homogeneity of two canonical designs for mobile microfluidic nuclear resonance (NMR) applications: parallel magnets with an air gap and a modified Halbach array. Along influence sample length, general design guidelines will be presented. For fair comparison, sensitive length has been chosen to same as size between ensure enough space transmitting receiving unit, well basic electric shimming components. Keeping compactness final device in mind, box edge 5 times defined, which complete magnet configuration should fit. With boundary conditions, simple cuboid reaches best without active ( 0.5B s , 41 ppm), while pseudo-Halbach highest strength 0.9B 994 assuming perfect magnets. However, permanent configurations suffer from imperfections, such magnetization, fabrication, positioning errors, results worse homogeneities than expected simulations using fixed parameter set. present sensitivity analysis cube studies variations magnetization angle purchased different suppliers, composed materials coatings, sizes. performed detailed Monte Carlo simulation on effect measured distribution properties mentioned configurations. The shows mean 430 ppm (std. dev. 350 Pseudo-Halbach 1086 (std 8 ppm).