提出了一种基于T形光栅的新型史密斯-珀塞尔自由电子激光器。并利用理论分析和粒子(Particle-in-Cell,PIC)模拟的方法研究了光栅形状对史密斯-珀塞尔自由电子激光器输出特性的影响。理论分析发现,基于T形光栅的史密斯-珀塞尔自由电子激光器的注-波互作用较强,电子束的群聚特性较强,相应地有较强的注-波转换效率,进而有较高的输出功率。PIC模拟发现,基于T形光栅的史密斯-珀塞尔自由电子激光器能够提高辐射功率。在电子束能量E=50 keV、电子束电流i=10 A、光栅周期D=0.3 mm的情况下:基于T形光栅的史密斯-珀塞尔自由电子激光器可以得到0.753949 THz、峰值输出功率约为2 kW的连续太赫兹辐射;而基于矩形光栅的史密斯-珀塞尔自由电子激光器只能得到0.723397 THz、峰值输出功率约为0.3 kW的连续太赫兹辐射。

A novel Smith-Purcell free-electron laser based on T-shaped grating is proposed herein. The influences of grating shape on the output characteristics of the Smith-Purcell free electron laser are discussed through theoretical analysis and Particle-in-Cell (PIC) simulation calculation. Through the theoretical analysis, it is found that the beam-wave interaction of the Smith-Purcell free electron laser based on the T-shaped grating and the bunching of electron beam are strong. Accordingly, the beam-wave conversion efficiency is strong, and the output power is high. Through the PIC simulation calculation, it is found that the Smith-Purcell free electron laser based on the T-shaped grating can increase the radiation power. Results indicate that a continuous-wave terahertz radiation at 0.753949 THz with a peak output power of approximately 2 kW can be obtained for a grating of period D=0.3 mm operating at a beam energy of E=50 keV and beam current i=10 A in this novel device. However, in the Smith-Purcell free electron laser based on rectangular grating, continuous-wave terahertz radiation at 0.723397 THz with a peak output power of approximately 0.3 kW can only be generated by the same electron beam (energy E=50 keV and beam current i=10 A) passing through the grating with the same size (D=0.3 mm).