Race-track fluxgate sensor scaling versus noise

Fluxgate sensors with a flat race-track core can provide significant advantages in terms of noise and manufacturing complexity. We present a comparison of parameters of several such sensors of a similar construction but with different dimensions that might be useful for a wide spectrum of applications, including state-of-the-art geomagnetic measurements. The effect of core demagnetization is discussed, and optical Kerr effect microscopy is used to present the results of the thermomagnetic treatment of these cores, which significantly improves overall sensor noise. Noise values between 9 and 2.5 pT
RMS
/√Hz at 1 Hz can be reached for core lengths of 17.5 to 78 mm.