太赫兹源是太赫兹科学与技术发展的关键一环，太赫兹Smith-Purcell自由电子激光（简称SP-FEL）是很有发展潜力的小型化、可调谐、高功率真空电子学太赫兹源之一。本项目提出一种新型结构的、基于超辐射机制的Smith-Purcell太赫兹自由电子激光设计方案，即采用开放球面谐振腔、环形电子束、三段柱形光栅结构（群聚段、漂移段、辐射段）。该结构具有电子束传输稳定、易于成型、束-波互作用效率高等特点。利用非线性理论、粒子模拟、实验测试等方法深入研究其谐振腔的高频特性、束-波互作用非线性特性、Smith-Purcell的超辐射机制和条件等，以获得该器件产生太赫兹（频率介于0.5THz-1.0THz）超辐射的最优结构参数和工作参数。探索这种结构实现可调谐、高功率、小型化太赫兹辐射源的可行性，进一步推动其实用化进程。

The terahertz(THz) radiation source is one of key issues for developing THz science and technology.The Smith-Purcell terahertz free electron laser (THz SP-FEL) is a potential for the development of compact, tunable and high-power vacuum electronics terahertz source. This project proposes a novel Smith-Purcell terahertz free electron laser operating in the super-radiant regime. The device consists of two open spherical cavities, a ring electron beam and a three-stage cylindrical grating (i.e. bunching stage, drift stage, radiating stage). It has the characteristics of an electron beam of transmission stability and to be shaped easily, a high efficiency of beam-wave interaction. Through the analysis of its high frequency characteristics, the super-radiance mechanism in this Smith-Purcell device, beam-wave interaction by using the nonlinear theory, PIC simulation and experiment test, a set of optimal operating parametera are obtained.The feasibility of the development of a low -cost, compact, tunable and high-power terahertz device. It is a valuable work to further promote the progress of their design and applications.