beam tetrode

例句：

1. 1. The beam tetrode is used in the detection of magnetic fields.
   束状管用于检测磁场。
2. 2. The beam tetrode was developed to improve the accuracy of the measurement.
   束状管的发明是为了提高测量的准确性。
3. 3. The beam tetrode was used to detect the presence of a specific element in the sample.
   束状管被用来检测样本中特定元素的出现。