Study On Airborne Fluxgate Magnetic Tensor Gradiometer

The magnetic gradient tensor is the spatial variation of the three components ofthe magnetic field along the orthogonal coordinate system, with nine components,because they contain more information, have more advantages than the traditionalmagnetic exploration, and are widely used in mineral prospecting, geological surveyand the military, having a good potential for development. Currently, Germany,United States, Australia and other countries carried out the magnetic gradient tensorinstrument system development work and a large number of field trials, and achievedcertain results. Aeromagnetic gradient tensor belongs to the restricted exports ofWestern countries cutting-edge technology, although the domestic data processing andinterpretation of the study to detect airborne magnetic gradient tensor has been acertain reserve, the study of the magnetic gradient tensor instrument system isbasically in the blank, therefore it has important practical significance to develop ourown design of the magnetic gradient tensor instrumentation system.The thesis is to design the airborne magnetic gradient tensor instrumentationsystem based on fluxgate, and the introduction of the composed instrument systemhardware and software modules is as follows.The magnetic gradient tensor instrumentation system hardware module includesthe power module, the fluxgate magnetic gradient tensor probe based on the "cross",the spherical feedback coil for tensor probe and its corresponding feedback circuitcomposed of the feedback module, the inertial navigation module based on IG-500N,the CRIO control module based on NI CompactRIO (CRIO) module, and thesingle-chip control module based on AT89S52. The instrument system takes the CRIOcontrol module and the single-chip control module as the core. By communicatingwith other modules, the functions of the acquisition, transmission, save and display ofthe measured data can be achieved by the instrument system. In that part, the article focuses on the descriptions of the overall design of the system hardware, introducesthe some of the basic hardware modules as well as the design of the critical hardwaremodules of the system. The instrument system has advantages of the small size, lightweight, and so on, applicable to the measurement of the aeromagnetic gradient tensor.The designed magnetic gradient tensor instrument system has been tested, it wasfound that it can achieve the basic functions of detection of the magnetic gradienttensor, and the power spectral density of the measured magnetic field components canreach0.12nT/Hz@1Hz by values，and the root mean square noise Vrmsequals to0.21nT in0.1Hz~10Hz. The power spectral density of magnetic gradient tensorcomponents can reach0.25nT/(m Hz)@1Hz by values，and the root mean squarenoise Vrmsequals to0.70nT/m in0.1Hz~10Hz, which satisfies the design requirements.The wild airship detecting car test was found that the instrument system can beapplied to the detection of airborne magnetic gradient tensor.