Low-Field Rampable Magnet for a High-Resolution MRI System

This article presents the design and experimental characterization of an electromagnet rampable up to 1 T and tailored to meet the demands of a magnetic resonance imaging (MRI) system conceived for spatial resolutions at the level of tens of microns. For high image quality, MRI requires a homogeneous magnetic field over the field of view (FoV) where the sample is imaged. We have opted for passive shimming based on optimal pole profiling and measure a relative field inhomogeneity of 71 parts per million over a spherical FoV of 20 mm diameter. Fringe-field lines are strongly confined to avoid interference with other devices. The magnet performance closely follows our expectations from numerical simulations in all of the experimental tests carried out. In addition, we present the solutions adopted for thermal management and the design of a mechanical structure to distribute the weight and integrate the platform to move the sample in and out of the magnet.