| Because the traveling wave tube combines high power with a wide frequency band,it has an irreplaceable position in many microwave electric vacuum devices.The traveling wave tube was developed from the 1940 s to the present and can now provide continuous wave kilowatt-level and pulsed megawatt-level power.It is widely used in many fields such as civil communication satellites,medical diagnostics and defense military electronics.With the continuous expansion of the application field and the requirements of the application environment,high-power traveling wave tubes have become a research hotspot.This paper mainly studies the Ka-band high-power traveling wave tube.The slowwave structure adopts two different design methods: conventional structure and overcutoff.At the same time,a transmission system with a good matching of the slow-wave structure is designed.The goal is to produce a power output greater than 5 kW in the 33-37 GHz frequency band to provide a theoretical basis and technical support for traveling wave tubes with greater output power in the future.In addition,this paper also studies the influencing factors and suppression methods of ion noise for ion noise that affects the performance of traveling wave tubes.The main research contents of this article are:1.The high-frequency characteristic theory of the slow-wave structure is introduced in detail.The effects of different size parameters of the slow-wave structure on its dispersion characteristics and coupling impedance are analyzed in detail,which provides a theory for determining the specific size parameters of the slow-wave structure.in accordance with.2.Using FWGTWT software to perform wave-wave interaction software calculation,it is obtained that the overall output power in the 33-37 GHz working frequency band is greater than 5kW under the working condition of voltage 24750 V and current 2.5A,the overall electronic efficiency in the frequency band is greater than 10%,and the gain is greater than 37 dB.Finally,the CST software is used to establish a three-dimensional simulation model on the known design structure to simulate the PIC particles of the whole tube,which demonstrates the correctness and feasibility of this design.3.Designed and simulated the hyperbolic arc transition waveguide,attenuator and energy transmission window.The simulation results show that the transmission system is well matched with the folded waveguide slow wave structure and the performance is excellent.4.A new type of phase-rate transition over-cut slow-wave structure scheme is proposed.The simulation results show that under the working conditions of voltage 25400 V and current 2.5A,the overall output power in the 33-38 GHz operating frequency band can be greater than 5kW,and the gain near the cut-off region is suppressed to reduce the risk of self-oscillation.Compared with the conventional folded waveguide slow wave structure,the electronic efficiency has been improved,especially the bandwidth has been expanded by 25%.5.Use two-dimensional particle simulation software OOPIC to analyze the ion noise.The change of the number of macro particles in the tube with time,the fluctuation frequency and amplitude of the average kinetic energy of the electrons are used as the characteristics of the strength of the ion noise.The in-depth analysis of time changes reveals the relationship between ion noise and vacuum,tube length,focusing magnetic field and collection level,and proposes a plan to suppress ion noise. |
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