Experimental evaluation of a yokeless permanent magnet

A recently developed theory of yokeless permanent magnets allows the design of magnetic structures capable of generating intense and uniform fields confined to arbitrarily assigned regions of space. A structure of particular interest for clinical application of nuclear magnetic resonance imaging is a magnet designed around a prismatic cavity of square cross section. A laboratory scale model of such a magnet has been constructed using ferrite as the magnetic material. This paper presents the results of a series of measurements of the magnet performance. In particular, the experimental results obtained with a thin magnet section are correlated with the theoretical model and the effects of the material and construction tolerances are analyzed.