Three-dimensional coil system for the generation of traceable magnetic vector fields

A precise and efficient way to calibrate 3D magnetometers is by utilizing triaxial coil systems. We describe the development and characterization of a 3D coil system that generates magnetic flux densities up to 2 mT in arbitrary field direction. Coil parameters, such as coil constants and the misalignment of its spacial axes are determined with nuclear magnetic resonance (NMR) techniques, ensuring traceability to SI standards. Besides the generation of a constant magnetic field inside a sphere of radius 1 cm in the center of the coil, the 3D coil system enables the realization of gradient and saddle field profiles, which allow a precise estimate of sensor positions in 3D. Fluxgate and Hall sensor measurements are carried out to characterize the quality of the generated magnetic fields. The homogeneity achieved the orthogonality, and the position and structure of the saddles are determined experimentally and compared to calculated values.