Study Of The Useful Life Of Long-term Stored Vacuum Electron Devices

Based on the general theories of the electrical vacuum device invalidation and the further detailed research, this paper depicts the model for evaluating the life of the electrical vacuum device. The model for evaluating the life of the electrical vacuum device is built up by theoretically analyzing some normal invalidation models and its researching principles, thereafter, some experiments have been done to prove its feasibility.This paper gives the normal distribution rules and the model of electrical vacuum device invalidation, and then deduces the general program to analyze the model. By investigating the invalidation mechanism, draws the conclusion that the increasing air pressure inside the vacuum tube is the major factor to influence the life of the electrical vacuum device in not-working-state. Meanwhile, the source of the air inside the vacuum tube is also studied, and then the relation between the air pressure inside the vacuum tube and time is set up. Combining the variation of the air pressure and the three invalidation period of the electrical vacuum device, the model for evaluating the life of the electrical vacuum device on not-working-state is raised by analyzing the change of the air pressure inside the vacuum tube.The measuring method of the air pressure inside the vacuum tube by applying the hot cathode ionization is presented given in this paper; also some circuit diagrams for the measurement are included. Under some certain conditions of the grid, the air pressure inside the vacuum tube can be figured out by measuring the ion current of the collecting grid and the cathode current. Because the ion current is very small in high vacuumed electrical device, the amplifier is designed to amplify micro measurement. The circuit diagrams for processing, setting, comparing, and alarming the ion current are conceived. When studying the electrical vacuum device which is for long time reservation, the ionization coefficient is an unknown element, which can be measured or simulated by analyzing the girds structure and potentials. A simple electrical vacuum device model is described in this paper, some simulations are given afterwards.The working principle, the developing status, trend and the key technology of the klystron are also introduced in this paper. The methods to judge the invalidation and the factors which make the invalidation are given as well. The indicating model of the invalidation of the klystron and the life time evaluation model of the klystron are proposed.