Vibration Characteristics Analysis Of Traveling Wave Tube In Working Conditions

Traveling wave tube(TWT), as a kind of electric vacuum device for amplifying signal power, is widely used in transportation, radar, mobile communication and other fields. It must be reliable and stable in working conditions. TWT is usually used in poor working conditions and will continue to suffer from the impact of vibration in the work. With the development of the miniaturization, high power and high efficiency of TWT, the reliability problems caused by the high heat loads are more and more prominent. At present, in domestic and overseas, the researches about the reliability of TWT mostly focus on thermal analysis of components and vibration analysis at normal temperature. Only a few scholars have been involved in the reliability research of components in working conditions(thermal-mechanical coupling physical field). System research on the heat and vibration characteristics of the whole tube in working conditions is lacking.In view of the complicated structure and high manufacturing cost of TWT, this paper analyzed and evaluated the vibration characteristics of whole tube in working conditions based on experiments and finite element method. Firstly, a finite element model of TWT was established on finite element software, and the modal analysis was carried out at normal temperature. Modal parameters such as natural frequencies and mode shapes in 3000 Hz were obtained. The modal test platform of TWT was designed and built to carry out experimental verification. Then, according to the experimental results, the model updating method of TWT’s sensitive design parameters based on the Kriging model was established, and the vibration model of the tube with the average deviation of 1% was obtained. Secondly, thermal analysis in working conditions was proceeded. Then the boundary conditions of thermal analysis were revised according to the results of temperature test. And the thermal analysis model of the tube was built up, which could reflect real situations of temperature distributions in working conditions. On the basis of modified thermal-mechanical coupling model, modal analysis under thermal stress was carried out to get modal parameters of the tube in working conditions. So the vibrating sensitive parts would be confirmed and the influences of high temperature on inherent vibration characteristics would be analyzed. Finally, the random vibration analysis was carried out to simulate the vibration of the working conditions. The response of vibration sensitive parts was obtained and used to evaluate the anti-vibration performance.According to the research of TWT’s modification method of finite element dynamic model and method of thermal-mechanical coupling, this paper set up a finite element model for studying the vibration characteristics of TWT in working conditions. The parameters of vibration characteristic and response are obtained, and the anti-vibration performance is evaluated. The technique for vibration analysis of the domestic TWT is established, which provides the technical support for design and process improvement of TWT.