Simulation And Experimental Study Of Terahertz Smith-Purcell Superradiation

Terahertz(THz)band has a frequency range between 100 GHz and 10 THz.Wavelengths between 30 ?m and 3 mm are in a particular area of the spectrum,and therefore have many unique properties.With a wide range of application prospects.The terahertz radiation source is a key technology for the development of terahertz technology.The vacuum electron radiation source is an important terahertz radiation source because of its large power and high efficiency.The development of these devices from the microwave to the terahertz band faced with bottlenecks such as scale effects.Smith-Purcell superradiation can solve the scale effect problem through higher harmonics.In this dissertation,the physical mechanism of Smith-Purcell super-radiation was analyzed by theory and simulation.The effects of various structural parameters on the dispersion characteristics were discussed.The influence of the sidewall structure on the starting current was analyzed.The contents of the simulation were verified by experiments.The following words are some specific contents of this thesis:(1)The dispersion equation of the sub-wavelength rectangular grating structure is deduced and the dispersion curve is drawn.The influence of different parameters on the dispersion characteristics of the structure is compared and the variation law is grasped.(2)Simulate the structure with particle simulation software,draw a good dispersion,and compare it with theoretical calculations.According to the required operating frequency,reasonable super-radiation angle,current current density in the laboratory and voltage environment,combined with theoretical calculations,various parameters of the structure are rationally designed.At the same time,the influence of the side wall with the same height on the two sides of the groove of the sub-wavelength rectangular grating structure is analyzed.(3)According to the previous simulation,the experimental platform,the electron gun part,and the super-radiation collection and detection part were reasonably designed and processed,and the relevant test research was conducted using the vacuum dynamic system.Through the precise centering of the electron gun,the beam size,beam stability,beam distribution,and the influence of the magnetic field on the beam position of the designed electron gun were measured.By changing the parameters of the filament,anode and cathode voltage,etc.,the changes of the beam current under different conditions were tested.