Low-noise,low-power-consumption seafloor vector magnetometer

The seafloor vector magnetometer is an effective tool for marine geomagnetic surveys and seafloor magnetotelluric(MT)detection.However,the noise,power consumption,cost,and volume characteristics of existing seafloor vector magnetometers are insufficient for practical use.Therefore,a low-noise,low-power-consumption seafloor vector magnetometer that can be used for data acquisition of deep-ocean geomagnetic vector components is developed and presented.A seafloor vector magnetometer mainly consists of a fluxgate sensor,data acquisition module,acoustic release module,glass sphere,frame,burn-wire release,and anchor.A new low-noise data acquisition module and a fluxgate sensor greatly reduce power consumption.Furthermore,compact size is achieved by integrating an acoustic telemetry module and replacing the acoustic release with an external burn-wire release.The new design and magnetometer characteristics reduce the volume of the instrument and the cost of hardware considerably,thereby improving the integrity and deployment efficiency of the equipment.Theoretically,it can operate for 90 days underwater at a maximum depth of 6000 m.The seafloor vector magnetometer was tested in the South China Sea and the Philippine Sea and obtained high-quality geomagnetic data.The deep-water environment facilitates magnetic field data measurements,and the magnetometer has an approximate noise level of 10 pT/rt(Hz)@1 Hz,a peak-to-peak value error of 0.2 nT,and approximate power consumption of 200 mW.The fluxgate sensor can measure the magnetic field in the lower frequency band and realize geomagnetic field measurements over prolonged periods.

AC vector magnetometer for space-based applications using low-resource magneto-impedance sensor

This study proposes a novel AC vector magnetometer developed using a low-resource magneto-impedance sensor for China’s Feng-Yun meteorological satellite(FY-3E).It was calibrated and characterized to determine its performance parameters.The total weight of the AC vector magnetometer is 51 g(the aluminum box excluded),while the total power consumption is 310 m W.The proposed AC vector magnetometer can detect magnetic field variations in the range of±1000 nT and noise power spectral density of≤50 pT/Hz^(1/2)@1 Hz.Furthermore,the proposed device has a maximum nonlinearity of≤0.71‰over the entire range and a nonorthogonality error of 3.07 nT or 0.15%(root mean square).The total dose hardness of the sensor is≥30 krad(Si).Furthermore,we propose the first survey results of a magnetometer equipped aboard a Chinese FY-3E satellite in a Sunsynchronous orbit.The data revealed that the AC vector magnetometer can detect transient physical signals such as quasistatic field-aligned currents(~50 nT)and waves at the auroral latitudes.These features render the proposed AC vector magnetometer suitable for space-based applications,particularly those involving the study of geomagnetic activity.

All-Optical Vector Cesium Magnetometer

Based on power modulation of a pump laser and precessional projection detection, we present an all-optical vector magnetometer of cesium, which has a demonstrated magnitude sensitivity of 80fF/Hz^1/2 and an orientation sensitivity of 0.1°/Hz^1/2. In the device, four main factors are measured experimentally, which are the Larmor precession frequency of a polarized magnetic moment that depends on the modulus of the measured m^gnetic field only, two phase shifts and amplitude ratio of the precession projection in the two probe directions relative to the magnetic field orientation. This kind of magnetometer with high sensitivity in the range of the spatial angle is suitable for solving the inverse problem and geomagnetic navigation.