Discussion on the Relationship Between Sensor Noise and Glass-Covered Amorphous Magnetic Wires Annealing Temperature

Fluxgate is a vectorial magnetic sensor that enables measure the quasi-static and low-frequency ac magnetic field by demodulating the variations near the excitation harmonics. Based on advantages such as high sensitivity and small volume, the fluxgate sensor is widely used for geo-physical mapping, mineral explorations, risk mitigations, and other applications. Fluxgate sensors measure the magnetic fields based on the nonlinearity and symmetry of the magnetization hysteresis curve of ferromagnetic materials. Therefore, the performance of the fluxgate sensor largely depends on the performance of the magnetic core material. In this work, the internal stress of the co-base amorphous wire core, the impedance of the coil that is tightly wound around the core, the sensitivity, and the noise level of the sensor are discussed, expressed, and experimental proofed with various annealing temperatures on the amorphous wires. The experimental results show that the derived relationships between the properties in materials and the performances of sensors in this article are correct and effective. In conclusion, by measuring the impedance of the core and coils, it could be predicted the optimum performances for fluxgate sensors and guide the sensor fabrications.