METHOD FOR CALCULATING THE INDUCED VOLTAGE IN A VIBRATING SAMPLE MAGNETOMETER DETECTION COIL SYSTEM

A numerical method for obtaining the vibrating sample magnetometer (VS M) sensitivity functions due to a uniformly magnetized sample in the s hape of ellipsoid, cuboid or cylinder, and then calculating the induce d voltage in a VSM detection coil systems is presented, The induced vo ltage, which depends on the equilibrium position and amplitude of the sample in three-dimensional space, and depends on the geometric parame ters of both sample and detection coils, is clculated from the viewpoi nt of magnetic charges. This numerical method is mole accurate than ot hers, which use dipole moment approximation without taking into consid eration the sample shape and size. By using this method. the induced v oltage, for which the shape and size effects of the sample must be tak en into account, can be calculated if there is knowledge of geometric parameters of the sample and coils. The formulas for calculating the c orrection coefficient are also given for samples whose shape errors sh ould be considered. Our results provide rigorous theoretical guidance for the exhaustive study of the VSM working principle, for accurate me asurement of the sample magnetic moment, and for optimum design of con figuration, position, and orientation of VSM pickup coils. (C) 1996 Am erican Institute of Physics.