In some embodiments, the magnet ring is pre-magnetized with a respective magnetization direction that maximizes uniformity of the magnetic field inside the inner volume. In other embodiments, the magnet ring is pre-magnetized with a respective magnetization direction that minimizes a fringe field outside the magnet array.

In an embodiment, the discrete magnet segments are electrically insulated from each other. In another embodiment, each of the discrete magnet segments has a shape that is one of a shape of sphere, a cylinder, an ellipsoid and a polygonal prism. In yet another embodiment, the discrete magnet segments are separated of each other by at least one non-magnetic element including a solid, gas or liquid.

In some embodiments, the magnet rings have a shape including one of an ellipse, a circle and a polygon.

In some embodiments, each of the mixed phase rings has a discrete rotational symmetry of at least an order eight.

In an embodiment, the magnet array further includes one or more additional arrays of magnet rings, wherein the magnet rings in the additional arrays are coaxial with respective longitudinal axes that are set at respective angles from the longitudinal axis.

There is additionally provided, in accordance with an embodiment of the present invention, a method for producing a magnet array, the method including positioning multiple magnet rings along a longitudinal axis and coaxially with the longitudinal axis, wherein at least two of the magnet rings are mixed-phase magnet rings that are phase-dissimilar, with the multiple magnet rings configured to jointly generate a magnetic field along a direction parallel to the longitudinal axis of at least a given level of uniformity inside a predefined inner volume. The multiple magnet rings are fixedly held in place using a frame.