A fluxgate sensor of high stability for low field magnetometry

A new fluxgate magnetometer sensor, highly stable with time and temperature, was developed for space magnetic exploration. The sensor, of ring-core construction, uses 6-81 Mo-Permalloy tape. When coupled with the NASA Ames Research Center driving and detection electronics, the resulting magnetometer has a zero offset level which is adjustable to less than 0.1 γ fluctuates less than \pm 0.1\gamma in 24 hours at constant temperature, and shifts less than 0.4 γ when the temperature of the sensor is shifted from -30 to + 60°C. Room temperature noise is less than 0.2 γ peak to peak in the frequency band of 0-10 Hz. This performance, which was confirmed by Ames in its fluxtank, was measured at the Naval Ordnance Laboratory in its superconducting shield, in which static magnetic fields are less than 0.1γ, static gradients are less than 0.1 γ/in, and the attenuation to time-varying fields is 10 6 .