Reliability Simulation and Analysis of a 340 GHz Traveling Wave Tube

With the rapid development of terahertz (0.1–10 THz) technology in biomedical sensing, space communication, and security inspection fields, the demands for high-reliability THz radiation sources are becoming increasingly urgent. As a key vacuum electronic device, the reliability of traveling-wave tube (TWT) is significantly affected by temperature and external vibration environment. In the present work, a systematic multiphysics coupling reliability analysis method for 340-GHz space TWT is proposed for the first time, covering thermodynamic, modal, and vibration simulations, and verified through extreme environmental experiments. Based on finite element analysis (FEA), the study shows the following key results: 1) under dynamic conditions, the highest temperature zone (212 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∘</sup>C) is observed at the end of multistage depressed collector (MDC) and the heat conduction path and substrate heat dissipation design effectively suppress the risk of temperature rise; 2) modal analysis shows that the root of the input/output window is a vibration-sensitive area (the first natural frequency of 1729.6 Hz) and external resonance should be avoided; 3) a safety matrix (SM) is introduced to evaluate vibration reliability, the ratio of equivalent stress (23.4 MPa) to material allowable stress under random vibration is SM = 2.7, which meets the safety threshold; and 4) in the -55 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∘</sup>C static low-temperature experiment, the measured temperature of the slow wave structure (SWS) had an error of about 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∘</sup>C compared to the simulations, which verified the accuracy of the multiphysics field coupling model. This article innovatively combines electromagnetic thermal force multifield simulation and extreme environment experiments to clarify the weak links and optimization directions of TWT in the THz band, providing important references for the design and engineering application of high-reliability vacuum electronic devices.