Compact spherical coil for fluxgate magnetometer vector feedback

Abstract

A novel design of a magnetic field feedback compensation coil system for triaxial fluxgate magnetometers is presented. The coils are wound on three concentric spherical shells of slightly different diameters with the fluxgate sensors placed in the 60 mm diameter internal field-free space. Measurements of the temperature coefficient and of the internal field homogeneity are given, and the noise performance is evaluated for a magnetometer incorporating the coil. The total outer diameter of the system is 90 mm and the weight is 350 g including the sensors. The main advantage of a vector feedback system is the exact definition of the magnetic axes. These are determined exclusively by the coil axes, and they are independent of even large angular displacements of the individual magnetic axes of the fluxgate elements.