Shi Hongyu, Wang Yanzhang, Chen Siyu, Lin Jun
Key Laboratory of Geophysical Exploration Equipment (Jilin University), Ministry of Education, Changchun 130021, China.
Rev Sci Instrum. 2017 Dec;88(12):125001. doi: 10.1063/1.5013015.
This study is motivated by the need to design a hybrid magnetometer operating in a wide-frequency band from DC to 10 kHz. To achieve this objective, a residence times difference fluxgate magnetometer (RTDFM) and an induction magnetometer (IM) have been integrated into a compact form. The hybrid magnetometer has a dumbbell-shaped structure in which the RTDFM transducer is partially inserted into the tube cores of the IM. Thus, the sensitivity of the RTDFM is significantly improved due to the flux amplification. The optimal structure, which has maximum sensitivity enhancement, was obtained through FEM analysis. To validate the theoretical analysis, the optimal hybrid magnetometer was manufactured, and its performance was evaluated. The device has a sensitivity of 45 mV/nT at 1 kHz in IM mode and 0.38 μs/nT in RTDFM mode, which is approximately 3.45 times as large as that of the single RTDFM structure. Furthermore, to obtain a lower noise performance in the entire frequency band, two operation modes switch at the cross frequency (0.16 Hz) of their noise levels. The noise level is 30 pT/√Hz in RTDFM mode and 0.07 pT/√Hz at 1 kHz in IM mode.
本研究的动机是需要设计一种在从直流到10 kHz的宽频带内工作的混合磁力计。为实现这一目标，将驻留时间差磁通门磁力计（RTDFM）和感应磁力计（IM）集成到一个紧凑的形式中。该混合磁力计具有哑铃形结构，其中RTDFM换能器部分插入到IM的管芯中。因此，由于磁通放大，RTDFM的灵敏度显著提高。通过有限元分析获得了具有最大灵敏度增强的最佳结构。为了验证理论分析，制造了最佳混合磁力计并对其性能进行了评估。该器件在IM模式下1 kHz时的灵敏度为45 mV/nT，在RTDFM模式下为0.38 μs/nT，约为单个RTDFM结构灵敏度的3.45倍。此外，为了在整个频带内获得更低的噪声性能，两种操作模式在其噪声水平的交叉频率（0.16 Hz）处切换。RTDFM模式下的噪声水平为30 pT/√Hz，IM模式下1 kHz时为0.07 pT/√Hz。
