free precession magnetometer

例句：

1. 1. The free precession magnetometer was used to measure the magnetic field around the Earth.
   使用自由进动磁强计来测量地球周围的磁场。
2. 2.The free precession magnetometer is a powerful tool for studying the behavior of the Earth's magnetic field.
   自由进动磁强计是研究地球磁场行为的强大工具。
3. 3. The free precession magnetometer has been used to detect and map the magnetic field lines in space.
   自由进动磁强计被用来探测和绘制太空中的磁场线。