Application of secondary electron composition contrast imaging method in microstructure studies on the microwave tube barium-tungsten cathode

The study of the secondary electron composition contrast imaging method has been developed with a conventional scanning electron microscope (SEM) equipped with ultra-thin window energy dispersive X-ray spectrometer (EDS). On the basis of the study of the principle of secondary electron emission, secondary electron composition contrast imaging method is investigated, and the ranges of its application are also discussed. This method is applied in the microstructure studies on the microwave tube barium-tungsten cathode. The results show that, compared with backscattered electron image, the secondary electron image can also reveal composition contrast well in certain conditions. Furthermore, the resolution of secondary electron composition contrast image is higher. In some cases, the secondary electron image can distinguish impurities which may bring wrong results. In the microstructure studies on the microwave tube barium-tungsten cathode, compared with backscattered electron image, secondary electron composition contrast imaging method is reasonable and practicable.