flux-gate magnetometer

A flux-gate magnetometer is a scientific instrument used to measure the direction and intensity of a magnetic field. Unlike a proton-precession magnetometer, which measures the magnitude of a field, the flux-gate device measures the three components of a vector field. It uses three sensors, each aligned with one component of the field. These sensors are transformers with a core of high-permeability material. When excited by a high-frequency sine wave, the output signal in the secondary winding contains even harmonics if a magnetic field is present. The amplitude and phase of these even harmonics are directly proportional to the field component along the sensor's axis. Flux-gate magnetometers are often used on spacecraft for magnetic field measurements.12