Abstract: A permanent magnet assembly comprising an essentially tubular magnet element which is radially magnetized, inner and outer members of a magnetic material resting against inner and outer sides, respectively, of the magnet element, and an annular top plate placed on one end of the outer member. The annular top plate and an end portion of the inner member form an annular air gap which is axially separated from the magnet element and across which the magnetic flux of the magnet element extends radially. The inner member has a polygonal outer surface. The magnet element is divided axially into a number of separate magnet segments having inner surfaces fixed to corresponding outer surfaces of the inner member.