Electron emitting features and design of thermionic electron area emission sources

In vacuum system, area source electron gun emits electrons to bombard the standard screen. With the first anode and the second anode in different potentials, the images show the features of divergent, uniform, convergence and submerge. Photos, images acquired by brightness meter, and the image gray values are listed in Table 1. By image gray value analysis, it can be seen that in item no. 1, the electrons emitted by area source electron gun are divergent ( not remarkable) ; in no. 2, it is uniform; in no. 3 it is convergence and in no. 4 it is submerged. It is deduced that when the voltage of first anode of electron gun is -4000 V and the second anode voltage is -2000 V, the fluorescence screen receives the uniformly distributed electrons. The difference is less than 5%. Based on this theory, the area source electron gun is developed. The electron gun is placed in a vacuum better than 1 x 10^-4Pa to be tested and it is further verified that its electron emission is uniform. The successful development of hot-electron area source provide an effective guarantee for testing the fluorescence screen parameters such as uniformity, brightness, luminous efficiency and afterglow .