Microwave vacuum electronic devices (VEDs) are the core components of xxxx equipment. The xxxx xxxx VEDs (xxxx devices) are equipped in the xxxx xxxx system, and xxxx in the xxxx state for a long time before use. So, their xxxx life will affect the reliability of the whole system. This paper reviews and summaries the status of xxxx life for the xxxx devices. Focusing on the key issues affecting the xxxx life of xxxx devices, the mechanism of state changes and the residual gas measurement inside the xxxx devices, the acceleration test method for their xxxx life and the xxxx life evaluation technology are explored in depth.
According to the xxxx environment of the xxxx devices, based on the competitive adsorption theory, the permeability model of mixed gas inside the xxxx devices is proposed and established. The model parameters are determined by the validated experimental data. Based on the finite element method and the model, the numerical analysis of the permeability in the complex structure xxxx devices can be carried out, and the correctness of the numerical analysis is verified for the actual device. For the device considering only permeation, the model is compared with the published basic and modified permeability models, and the expected xxxx life of the device is given as > 50 years, 1 hour and 609 days, respectively. The results show that the proposed model is suitable for analyzing the influence of permeation on the xxxx tube environment. The model is applied to analyze the gas permeation rate of the core component in a spaceflight unit, which is xxxx in pure nitrogen, helium and air, respectively, after sealed by borosilicate and single crystal silicon glass. The results show that the time is lower than expected storage life (12 year) when the vacuum inside the component xxxx in helium and air is lower than the threshold; the gas permeability inside the component stored in nitrogen is minimum, which failure can be avoided.
We proposed a non-contact residual gas test method based on Rayleigh scattering. And we made an analysis of the effects of residual gas type, concentration and scattering angle on the scattered light intensity. It was found that large gas molecules, small scattering angles and wide pulses can improve the scattered light intensity and reduce the difficulty of testing. The effect of air-scatter light, mirror and metal reflected light on the scattered light test is analyzed. It is found that the air-scatter light and mirror reflected light will submerge residual gas scattered light, so they must be isolated. We designed a xxxx tube with ambient light isolators and viewing windows, and developed a scattering light receiving subsystem, and set up a residual gas change test platform based on UV excimer laser. Then we analyzed effect of the measured pulse repetition frequency, test angle, test distance and incident light intensity on the scattered light intensity. Based on the test platform, we test the residual gas scatter light three times respectively, when the xxxx tube was manufactured, xxxx for xxxx years. The results showed that the residual gas scatter light intensity raised about xxxx times higher than intensity when the xxxx tube was manufactured, it implied that the residual gas rised to xxxx Pa.
After analyzing the xxxx tube failure mechanism, we chose air pressure as the acceleration stress for the xxxx tube, and then established a xxxx life acceleration model based on pressurization. After then we established a remaining storage life prediction model for xxxx life based on Bayesian theory, and modified the parameters of the ion flow degradation rate of the xxxx tube according to the posterior probability, and adjusted the Bayesian parameters to increase the accuracy of the results. After then we presented another remaining xxxx life prediction model based on the segmented similarity comparison, which compare the similarity between the test xxxx tube and the reference storage tube performance data according to the maintenance time segment, then obtained the xxxx tube remaining life by weighted average.
We developed a xxxx tube accelerated life test platform using pressure as accelerated stress, and realized the function of the xxxx acceleration control, detection and recording. Based on the platform, one xxxx klystron was xxxx under xxxx atm. It is found that the cathode current dropped faster under accelerated xxxx. So the xxxx life of this klystron was xxxx years and the acceleration xxxx life was xxxx years, and it proved the validity of the xxxx life acceleration model based on pressurization. Based on the two remaining storage life prediction model, we analyzed the long-term monitoring data of 59 xxxx xxxx tube provided by the CEC 12th research institution. The flow degradation rate of each xxxx tube was calculated based on the Bayesian xxxx residual life prediction model, and it’s found that the xxxx life reliability of xxxx years was xxxx. After analyzing the residual xxxx life prediction error of the three storage tubes, it’s found that the average prediction error reached the minimum when the xxxx was xxxx and the xxxx was xxxx.