magnetic focusing indicator tube

例句：

1. 1. This instrument is used to measure the magnetic field strength of the Earth's core.
   这个仪器用来测量地球核心的磁场强度。
2. 2. The magnetic focusing indicator tube is a crucial component in the navigation system.
   磁聚焦指示管是导航系统中至关重要的组成部分。
3. 3. The magnetic focusing indicator tube was developed to improve the accuracy of magnetic field measurements.
   磁聚焦指示管的开发目的是为了提高磁场测量的准确性。