Rock magnetic applications of Halbach cylinders

Permanent magnet field sources made of NdFeB, in particular the Halbach cylinders, have not previously been used by rock magneticists. Here, their use is explored for determining saturation IRM (SIRM) and S ratio. An original "one-step" scheme is presented to obtain both parameters in one measurement and one operation of IRM acquisition using two crossed Halbach cylinders with 1.0 and 0.3 T fields. The first tests performed demonstrate the ability of Halbach cylinders to derive SIRM and S values over a wide range of coercivities using both the standard and the one-step schemes, although further improvements are needed in field homogeneity to achieve better precision. Other possible applications of Halbach cylinders are reviewed. (C) 2001 Elsevier Science B.V. All rights reserved.