Backward-wave Interaction And Instability Suppression Of Traveling Wave Tube

With the development of terahertz technology and the increasing requirement for the power and efficiency of TWTs in practical applications,various new types of TWTs are constantly emerging.Back-wave is a improtent problem in all TWTs.For example,the main problem solved by high-power TWT is to increase the output power,which can easily cause backward-wave oscillation.Backward-wave is also used as a terahertz source of terahertz TWT which is a hot research field.Therefore,the backward-wave has been a hot topic in TWT research since it was discovered.The shape of slow-wave structures of various TWTs is different,so a set of models which can accurately and rapidly simulate the interaction of backward waves of various TWTs is urgently needed.Relying on specific scientific research projects,this paper focuses on the model of backwave interaction of various types of TWTs and compares the simulation results as follows:1)Aiming at the need for a set of models to describe the backwave interaction of all kinds of TWTs,this paper puts forward a general model of TWT backwave interaction by studying the common characteristics of TWTs and the backwave model,and completes the development of matlab code for this model This model can describe the interaction process of various TWTs' backward waves,and quickly obtain their oscillation frequency and starting point.2)In view of the validation of the general model of backward wave interaction,this paper uses this model to simulate the backward wave of a terahertz folded waveguide TWT operating near 0.22 THz frequency band,and quickly calculates its oscillation frequency and start-up length.The simulation results are basically in agreement with the measured results.The backward wave of a helical TWT operating near 17.5GHz frequency point is simulated.The wave is simulated and the calculated results are basically in agreement with the measured ones.The back-wave of a new type of V-band high-power band-beam traveling wave tube is simulated,and the oscillation frequency and starting point of the new type of traveling wave tube can be quickly calculated.3)In order to solve the problem of back-wave oscillation suppression,this paper uses the general model of back-wave interaction to get the oscillation frequency and starting length of a traveling wave tube,and then quickly determine the location of the built-in attenuator.By adding the attenuated back-wave gain map,it can be seen that this method can solve the problem of back-wave oscillation in the design process of various TWTs in a short time.On the basis of putting forward the general model of TWT backward wave interaction and developing relevant codes,the accuracy of the model is proved by comparing the simulation results with the measured results of three different TWTs.The model can be used to simulate the backward wave interaction process of various TWTs quickly,and on this basis,the instability of TWTs caused by the backward waveguide can be solved effectively and quickly.