Thermal Analysis Of Electron Gun And Collector For Traveling Wave Tubes

TWT(traveling wave tube) is an important high-power microwave amplifier with the advantages of wide frequency band, high power, high efficiency, environmental adaptability and other advantages, and it is currently widely used. Thermal a nalysis has become an important part of the analysis of TWT because that the thermal issues affect the performance of TWT. With the rapid development of the computer aided design technology of microwave tube, it is very necessary to use software to simulate the temperature distribution of traveling wave tube in the design process and to help the design.The main contents are as follows:1.Thermal analysis of TWT electron gunThe paper studies the different thermal boundary conditions of TWT electron gun when it works in the natural environment and the vacuum environment. It uses ANSYS to calculate the temperature distribution of the electron gun in both working environment. And it observes the temperature of the cathode and the temperature of center of cathode over time. For the electron gun working in vacuum environment, the paper also studies the effect on the electron gun when temperature of the vacuum environment varies from-50 degrees Celsius to 80 degrees Celsius, the results show that temperature of vacuum environment has little effect on the temperature of the cathode and temperature variation of the cathode does not exceed 0.5 degrees Celsius. The thermal deformation has been calculated by heat-stress coupled analysis using ANSYS. Based on the deformation of the cathode, anode and control electrode, impacts on the emission current, shot distance and waist radius of the electron gun have been analyzed with MTSS. The results show that these parameters have increased because of the thermal deformation and the waist radius has increased mostly.In addition, the paper has compared the difference of the cooling capacity of the electron gun when it works in in the natural environment and the vacuum environment. The conclusion is that the natural environment is of a stronger cooling capacity. By applying the certain same power on the heater, it calculates and compares the temperature of the cathode when the electron gun works in the natural environment and in vacuum environment, the results show that when working in the natural environment, the temperature of the cathode is 2 degrees Celsius lower than the temperature of the cathode when working in the vacuum environment. It establishes a complete model of the electron gun and a simplified model of the electron gun(only the cathode, the cathode tube, heater) in ANSYS, and it applies the same thermal boundary to calculate the temperature of the cathode, the results are not even close. When establishing the model of the electron gun in ANSYS, the paper has studied the influence of the shape of the heater on the results of the temperature distribution. And the result is that the shape of the heater has no influence on the calculation results if the power on the heater keeps the same and the other settings remain the same in ANSYS. The relationship between the temperature of cathode button and the ambient temperature of the two enclosures set in the electron gun has been analyzed.2.Thermal analysis of TWT collectorThe paper studies the methods to calculate the uniform heat flux distribution and non-uniform heat flux distribution on the inner surface of the collector by using MTSS. And it calculates the temperature distribution of the collector by using that two kinds of heat flux, the results show that both the overall temperature distribution is substantially the same. But the high temperature part is at the end of the collector which is closer to the actual situation when applying the non- uniform heat flux distribution on the inner surface of the collector.