Leakage failure analysis of pole pieces used for traveling wave tube

The excellent performance of the traveling wave tube (TWT) depends on the eligible gas-proof property material used in it. As part of the vacuum system of traveling wave tube, the quality of pole pieces directly affects the reliability of TWT. A gas leakage was detected after a new group of pole pieces adopted. In this work, compared with normal and leaking pole pieces, a scanning electron microscopy (SEM) and electron probe energy dispersive spectroscopy (EDS) were carried out on the microstructure and micro-area composition analysis. Causes of the gas leakage were tried to study. The results showed that, inappropriate turning and electroplating technology affected the later welding process, leading to a gas leakage eventually. Through improved technology, this problem could be solved successfully.