Building a Better Fluxgate Core – Implications for Future Magnetic Field Instruments

Abstract:

We present the results of recent work to develop and demonstrate a next-generation fluxgate magnetometer to provide robust, highly stable, and sensitive magnetic field measurements. The noise floor of a fluxgate is typically limited by the intrinsic magnetic noise of a ferromagnetic core that is periodically driven into magnetic saturation to modulate the local magnetic field. We show laboratory results of a parametric optimization of fluxgate core manufacturing and the impact of geometry, foil thickness, heat treatment temperature, cooling rates, and number of foil layers. We demonstrate a new design and manufacturing process that consistently produces low magnetic noise and requires less power than previous designs. We also show how the developed manufacturing process can be adapted to produce miniature cores for small nanosatellite applications and different core geometries enabling new styles of fluxgate sensors with promising characteristics. Fluxgate magnetometers built using this new technology will fly on the ACES-II sounding rocket, nominally December 2021, and form part of a recently funded Technical Demonstration flight on the TRACERS SMEX mission, nominally launching in 2023. This flight heritage, combined with the robust and consistent manufacturing process, should enable the streamlined production of the tens to hundreds of instruments required for future constellation missions.