The induction magnetometer in the Phase II of Chinese Meridian Project

• Main Authors: Xizhen Wang, Zhisheng Feng, Haihua Ju, Bin Yan, Xinxin Ma, Zhiqing Chen
• Format: Article in Journal/Newspaper
• Language: Chinese
• Published: Editorial Office of Reviews of Geophysics and Planetary Physics 1481
• Subjects: chinese meridian project; geomagnetic monitoring; induction magnetometer; Geophysics. Cosmic physics; QC801-809; Astrophysics; QB460-466; Antarctic; Antarc*
• Online Access: https://doi.org/10.19975/j.dqyxx.2023-015; https://doaj.org/article/c2b6375225b54d47854043c6e712166a

The Earth's induced magnetic field is a result of the electrical current that is generated by the space current system within the Earth's interior. By observing Earth's induced magnetic field, we can acquire information on the space current system and the electrical structure of the Earth's interior, which is an important physical parameter to study the mechanism of space weather events and seismic sphere coupling. The Meridian Project has set up several induction magnetometers in the shape of a "#" along the longitudes of 120° E and 100° E and latitudes of 30° N and 40° N in China's mainland and Antarctic regions, to carry out fixed, long-term, and continuous measurements of the Earth's induced magnetic field. The first phase of the Meridian Project is equipped with 14 LEMI-30 induction magnetometers produced by Ukraine, which have been in routine operation since 2009 and will be integrated with the grid of the second phase of the Meridian Project. Thirteen induction magnetometers will be installed in the second phase of the Meridian Project, which is scheduled to commence operation in 2023. Together with the equipment already installed in the first phase of the Meridian Project, a network of 27 induction magnetometers will be established. China is independently developing the induction magnetometer of the second phase of the Meridian Project. The magnetic core incorporates a new alloy material with high permeability. The multi-piece superposition technology was adopted to effectively gather the magnetic field, enhance the induction output signal, and improve the sensor's ability to pick up weak signals. The test results show that the frequency range of the induction magnetometer used in the second phase of the Meridian Project is wider, up to 0.001–30 Hz; its sensitivity is high, with a resolution of 10 pT; and its long-term operation is very stable.