A new spinner magnetometer: principles and techniques

Summary Design scheme, theory of operation, and practical techniques of a new spinner magnetometer are developed and tested. In this apparatus, a pair of bevel gears are used to rotate the sample simultaneously around two orthogonal axes, and magnetic signals are picked up by a fluxgate sensor, amplified by a programable gain amplifier, and sampled by an analogue - digital (AD) converter at timing signals from a rotary encorder. Magnetic signals contain many frequency components corresponding to dipole terms, quadrupole terms, and so on, and calculation of magnetization can be done by the fast Fourier transform (FFT) technique. As there is no need to replace the sample during a measurement, this new magnetometer is easily adapted to digital control and automatic measurement using a microcomputer. These possibilities are briefly discussed.