A unilateral magnet with an extended constant magnetic field gradient

■■■. [Display omitted] ► Constant gradients of more than 3 cm extent are achieved with a three magnet array. ► The extended constant gradient allow to select spins several cm into the object. ► A solenoid can be combined with the constant gradient for rock core plug analysis. Unilateral magnetic resonance (UMR) has become, in different research areas, a powerful tool to interrogate samples of arbitrary size. Numerous designs have been suggested in the literature to produce the desired magnetic field distributions, including designs which feature constant magnetic field gradients suitable for diffusion and profiling experiments. This work presents a new approach which features extended constant magnetic field gradients with a three magnet array. Constant gradients of more than 3 cm extent can be achieved in a very simple, compact and safe design. Diffusion measurements from different positions over the magnet are presented in addition to practical applications for reservoir core plug characterization. The idea of a solenoid as a probe for specific measurements in UMR is introduced. Simple profiling experiments are also presented.