Research On High Frequency Characteristics And Experiment Of 300GHz Backward Wave Oscillator

The Terahertz(THz)wave refers to an electromagnetic wave having a frequency in the range of 0.1 THz to 10 THz(wavelength between 3?m and 3 mm).Terahertz technology is a very important cross-cutting field and its application is very extensive,such as THz time-domain spectroscopy,THz imaging,safety inspection,THz radar,astronomy,terahertz radiation,and biomedicine.In recent years,too Hertz science and technology has developed rapidly with the development of its mechanism,technology testing and application technology.In terahertz science and technology,the terahertz source is the basis of all scientific research and applications.Vacuum electronics is one of the important methods for generating terahertz radiation sources.The backward wave tube is one of many vacuum electronics devices.It utilizes the interaction between the return wave on the slow-wave structure and the electron beam to generate microwave oscillations,which have a unique role in generating terahertz radiation.The high-frequency system of the backward wave tube is the main part of the backward wave tube.Studying the high frequency system of the backward wave tube can be done logically and complete the study of the corresponding backward wave tube.This thesis mainly studies the slow wave structure of the backward wave tube.The slow wave structure is the core component of the backward wave tube.It is a periodic high-frequency system and can transmit backward slow electromagnetic waves(back wave)in a sufficiently wide frequency band.It is also an important place where the interaction of electron injection and electromagnetic waves occurs.In this paper,rectangular double gratings are selected as the slow-wave structure of the terahertz wave.The CST and MAGIC software are used to calculate the simulation of the cold cavity and the hot cavity of a rectangular double-grating at 300GHz,respectively.It was experimentally studied later,but due to the 300GHz rectangle Double gratings are very difficult to test,so we decided to do a double-grating experimental study at low frequency(140GHz).Before the experiment,we also calculated the cold cavity and the thermal cavity for a 140GHz rectangular double grating.To facilitate the two different frequencies The rectangular double gratings are compared.This paper focuses on the effects of the groove depth,period,lateral width,and voltage of the rectangular double gratings on their dispersion curves.Studies have shown that the groove depth and period of double gratings are inversely proportional to the dispersion curve,and the voltage It is proportional to the dispersion curve,and the lateral width has little effect on the dispersion curve.In this paper,the simulation of the cavity simulation mainly studied the optimal voltage,output power and starting current density of rectangular double gratings at 140GHz and300GHz.The results show that the optimal voltage of140GHz rectangular double gratings is 6.4kv,the output power is 343w,and the starting current density.For 15A/cm~2,the optimal voltage for the 300GHz rectangular double grating is 15kv,the output power is 47w,and the starting current density is 40A/cm~2.Based on a large number of theoretical calculations and simulation calculations,the high frequency structure is cooled.Measurement design and processing,as well as thermal measurement of the entire tube design and experimental platform construction.These studies are far-reaching for the development of terahertz backward-wave tubes.