Preprints
https://doi.org/10.5194/gi-2021-30
https://doi.org/10.5194/gi-2021-30

  12 Nov 2021

12 Nov 2021

Review status: this preprint is currently under review for the journal GI.

Contributors to Fluxgate Magnetic Noise in Permalloy Foils Including a Potential New Copper Alloy Regime

David M. Miles1, Richard Dvorsky1, Kenton Greene1, Christian Hansen1, B. Barry Narod2, and Michael Webb1 David M. Miles et al.
  • 1Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa, 52242, USA
  • 2Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, Canada

Abstract. Fluxgate magnetometers provide sensitive and stable measurements of the static and low frequency vector magnetic field. Fluxgates form a magnetic field measurement by periodically saturating a ferromagnetic core and the intrinsic magnetic noise of this material can determine the noise floor of the instrument. We present the results of an empirical experiment to understand the physical parameters that influence the intrinsic magnetic noise of fluxgate cores. We compare two permalloy alloys – the historical standard 6 % molybdenum alloy and a new 28 % copper alloy. We examine the influence of geometry using the historical standard 1” diameter spiral wound ring-core and a new stacked washer racetrack design. We evaluate the influence of material thickness by comparing 100 µm and 50 µm foils. Finally, we investigate heat treatments in terms of temperature and ramp rate and their role in both grain size and magnetic noise. The results of these experiments suggest that thinner foils, potentially comprising the copper alloy, manufactured into continuous racetrack geometry washers may provide excellent performance in fluxgate sensors.

David M. Miles et al.

Status: open (until 18 Dec 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on gi-2021-30', Dave Sheppard, 30 Nov 2021 reply

David M. Miles et al.

David M. Miles et al.

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Short summary
We present an experiment intended to enable extremely low-noise magnetic field measurements. We manufactured fluxgate magnetometer cores using two metal alloys, two geometries, two foil thicknesses, and six different heat treatments and compared the resulting material properties, power consumption, and magnetic noise. Our results suggest that thinner foils, potentially using a new copper alloy, manufactured into continuous racetrack washers may provide excellent performance in fluxgate sensors.