Research On Terahertz Smith-Purcell Superradiation And Output Resonant Cavity

In the electromagnetic spectrum,terahertz waves have non-negligible value in many fields due to their high resolution,low energy,and high penetration.The development of radiation source technology is an important link in the development of terahertz science and technology.For radiation sources,vacuum electronic devices are an extremely important type.At present,high-frequency terahertz vacuum devices face problems such as difficult processing and weak output power.Starting from the Smith-Purcell theory,through theoretical derivation and simulation calculations,this thesis explores the structure that can realize the Smith-Purcell superradiance enhancement,and provides a certain reference for the realization of a small-sized and high-power terahertz vacuum radiation source.The main research contents and results of this thesis are as follows:1.The dispersion equation of the periodic plate grating is theoretically derived,and the influence of different grating parameters on the dispersion curve is studied.And by adjusting the structural parameters,the radiation mechanism of the grating is fully grasped,and the theoretical basis is familiar.2.Through the simulation calculation in CST,a new type of grid trench structure is studied,and it is verified that the structure can break through the frequency doubling limit and realize the tuning and enhancement of the Smith-Purcell high-order harmonic superradiation of a specific frequency.,which provides a new idea for the development of this type of vacuum radiation source.3.The effect of the quasi-optical resonator on the frequency selection and resonance enhancement of superradiance was studied.The three-mirror quasi-optical cavity was calculated in the CST particle studio.By adjusting the parameters such as the size and position of the mirror,the The resonance amplification of the Smith-Purcell superradiance higher harmonics verifies that the three-mirror quasi-optical cavity has the characteristics of enhanced superradiance.4.For the cold measurement research of the three-mirror quasi-optical cavity,a lot of simulation calculations and processing designs have been done.Different coupling-out structures were tried in the simulation software,and a reliable cold-measuring machining structure was designed based on the simulation results.It provides a reference for the output structure of the new three-mirror quasi-optical cavity,and also has a certain role in promoting the development of terahertz vacuum radiation sources.