Sui Yangyi, Li Guang, Wang Shilong, Lin Jun
College of Instrumentation and Electrical Engineering, Jilin University, Changchun 130026, China.
Rev Sci Instrum. 2014 Jan;85(1):014701. doi: 10.1063/1.4856675.
The magnetic tensor gradiometer, which is used for measuring the spatial derivatives of three orthogonal magnetic field components, is an important magnetic field characterization tool. Here, the construction of a magnetic full-tensor gradiometer is described, which utilizes four fluxgates arranged on a planar cross structure, and a single, triaxial, spherical feedback coil assembly. In this arrangement, one of the fluxgates is used as a reference, controlling the currents through the feedback coils. Since the fluxgates are working in the near-zero magnetic field environment, the magnetic tensor gradiometer is stable and of an improved accuracy. This design avoids the crosstalk normally caused by individual feedback coils for each fluxgate, and reduces the orthogonality and orientation errors. Moreover, the calibration parameters can be directly inferred using the spherical feedback coil. The measured gradient tensor magnitude can reach 0.52 nT/m/Hz(1/2) @ 1 Hz in unshielded laboratory conditions, while exhibiting good noise immunity. The functionality of the system is verified by locating a small, single, permanent, and dipole magnet in space. The gradiometer is compact, while employing global feedback, and therefore it is especially suitable for deployment on space-constrained moving platforms.
用于测量三个正交磁场分量空间导数的磁张量梯度仪是一种重要的磁场表征工具。本文描述了一种磁全张量梯度仪的构造，它利用四个布置在平面十字结构上的磁通门以及一个单轴、三轴球形反馈线圈组件。在这种布置中，其中一个磁通门用作参考，控制通过反馈线圈的电流。由于磁通门在近零磁场环境中工作，磁张量梯度仪稳定且精度有所提高。这种设计避免了通常由每个磁通门单独的反馈线圈引起的串扰，并减少了正交性和方向误差。此外，校准参数可使用球形反馈线圈直接推导得出。在无屏蔽实验室条件下，测得的梯度张量幅度在1 Hz时可达0.52 nT/m/Hz(1/2)，同时具有良好的抗噪声能力。通过在空间中定位一个小的、单极、永磁偶极磁体来验证系统的功能。该梯度仪紧凑，采用全局反馈，因此特别适合部署在空间受限的移动平台上。
