HALBACH MAGNET ARRAY FOR NMR INVESTIGATIONS

摘要

A magnet array for use with NMR signal acquisition apparatus uses rod-shaped magnets located at the corners of a square. The square lies in the (x-y) plane of a three dimensional Cartesian coordinate system and the long axes of the magnets extend generally along the z-direction such that the polarisation vectors of the magnets lie substantially in the x-y plane. The magnets are arranged to create a substantially uniform magnetic field B₀ in a sample volume at the centre of the polygon. The widths of the magnets are less than the length of the sides of the square so that there is a gap between magnets allowing lateral access in the x-y plane to the sample volume. Each magnet may be rotatable about its longitudinal axis to change one and/or both the B₀ field direction and magnitude in the sample volume. At least one magnet may be displaceable in a direction orthogonal to its longitudinal axis to change one and/or both the B₀ field direction and magnitude in the sample volume.