Dipolar Halbach Magnet Stacks Made from Identically Shaped Permanent Magnets for Magnetic Resonance

NMR Mandhalas (Magnetic Arrangement for Novel Discrete Halbach LAyout) are arrays of identically shaped magnets in a Halbach-type arrangement. They provide a simple and cost-effective way to generate high magnetic fields for mobile applications, for example, in magnetic resonance. Based on the introductory publication by Raich and Blumler (Concepts Magn Reson 2004;23B:16-25), we extend the notion of Mandhalas from cube-shaped magnets to polygonal and cylindrical ones and present construction guidelines for the stacking of such rings to generate homogeneous magnetic fields over larger volumes. For this purpose, we present formulas and numerical values based on a dipole approach to calculate the flux density of single rings and composed 3D systems and compare to corresponding results obtained by 3D boundary element method calculations. As an application of the approach presented here, we constructed prototypes. (C) 2010 Wiley Periodicals, Inc. Concepts Magn Reson Part A 36A: 211-222, 2010.