Stabilized magnetic vacuum using a rotating fluxgate sensor

We present an effective zero-field system utilizing a rotating, single-axis fluxgate sensor to establish and maintain a magnetic vacuum in triaxial coils. With the help of a low-noise fluxgate sensor rotating at a frequency of 1 Hz, we were able to set the magnetic zero in the horizontal plane to or below 0.5 nT, which is 10 ppm of the local magnetic field, or 100 dB suppression. With the help of an additional triaxial sensor at a 2.5-m distance, we were able to maintain the magnetic zero to about 1 nT within 30-minutes suppressing field variations and disturbances. Such a system allows for precise magnetic calibrations, paleomagnetic experiments or other tasks where magnetic vacuum is beneficial or required.