A Design Of G-Band BWO Based On Truncated Sine Waveguide

The electromagnetic wave in the frequency of 220 GHz has extensive applications in terahertz communications,weapon manufacture,and radar detection.These applications require high-power radiation sources.Vacuum electronics can produce high power microwave sources at high frequencies.The common “O” type high power radiation sources are traveling wave tube,klystron tube,and backward wave tube.The backward wave oscillator(BWO)can be used as the front-end driving source of the amplifier.Therefore,it is necessary to study the backward wave tube in the frequency of 220 GHz.In this paper,based on the flat-top sinusoidal waveguide as the slow-wave structure,a pencil electron-beam back-wave oscillator and two sheet electron beam back-wave oscillators working in the G-band are designed.Through software simulating calculation,the parameters of these three backward wave oscillators have reached the design targets.The specific work of this article is as follows:1.The three-dimensional electromagnetic simulation software HFSS is used to study the slow-wave characteristics of flat-top sinusoidal waveguides.At the same time,the dispersion characteristics and coupling impedance of flat-top sinusoidal waveguides and conventional sinusoidal waveguides are compared.The comparison results show that the coupling impedance of flat-top sinusoidal waveguides at 220 GHz is about 29.4% higher than that of conventional sinusoidal waveguides,and the difference in dispersion characteristics between the two is small.2.Proposed a G-band pencil electron beam BWO based the flat-top sinusoidal waveguide.The CST software is used to design the high-frequency system of the BWO,including the slow wave structure,the energy transmission structure,the attenuator,and the pencil electron channel.The CST software is used to study the beam-wave interaction of the BWO.The simulation results show that,when the pencil electron's current is 9mA,the voltage tuning range is 15~25kV,the output power of the BWO is more than 1.1W in the frequency of 207.95~233.82 GHz.3.Based on the research of the pencil electron beam BWO,the sheet electron beam BWO is studied from the same current and the same current density.The simulation results show that at the same operating current,the band sheet electron current is 9mA.Due to the small current density of the sheet electron current,the required focusing magnetic field is 0.2Tesla.When the voltage tuning range is 15~25kV,the output power of the BWO is more than 1.02 W output power in the frequency of 207.02~232.30GHz;at the same current density,the current in the sheet electron beam can reach 42 mA,and the focusing magnetic field at this time is 0.4Tesla.When the voltage tuning range is 15~25kV,the output power of the BWO is more than 9.56 W output power in the frequency of 207.08~233.04 GHz.These devices have a watt-level power output in the G band,which fully illustrates the potential application value of a flat-top sinusoidal waveguide return tube as a high-power terahertz radiation source.