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THz波的产生有多种途径,清华大学加速器实验室正致力于发展基于相对论电子束的高峰值功率的THz辐射源。本文分别从高峰值流强的单束团与基于激光整形的多脉冲束团序列出发,介绍实验室在宽谱高电场梯度和准单频可调谐THz辐射等方面的研究进展。高亮度电子束团由新一代光阴极电子枪产生,经3 m行波加速管加速,能量可达~50 MeV,采用速度压缩机制可使束团长度达到百飞秒量级。该超短相对论束团可通过多种机制产生高峰值功率的THz辐射,目前,实验室已通过相干渡越辐射(CTR)获得单脉冲能量18μJ的THz辐射输出。同时,提出了一种结合欠压缩工作模式和漂移压缩方法的新束团压缩方案,可进一步将束团压缩至几十飞秒,有望获得频率范围为0.1 THz~30 THz的超宽谱THz辐射。本文同时介绍了多脉冲超短电子束序列的束团测量实验结果,通过模拟研究验证了基于该束团序列CTR产生高功率、可调谐准单频THz辐射的可行性,并进行了相应的实验方案设计。
There are many ways to generate THz waves. Tsinghua Accelerator Laboratory is working on the development of THz radiation source based on the relativistic electron beam with high peak power. In this paper, the research progress of wide-field high-field gradients and quasi-monophyletic tunable THz radiation in laboratories is introduced from single-beam group with high peak current and multi-pulse bunch sequence based on laser shaping. High brightness electron bunches are produced by a new generation of photocathode and accelerated by 3 m traveling wave accelerators with energy up to ~ 50 MeV. The speed compression mechanism allows the bunching length to reach the order of hundred femtoseconds. The ultrashort relativistic beam group can generate THz radiation with high peak power through a variety of mechanisms. At present, the laboratory has obtained a THz radiation output of 18 μJ with single pulse energy through coherent transition radiation (CTR). At the same time, a new beam compression scheme combining under-compression mode and drift compression method is proposed, which can further compress the beam to dozens of femtoseconds, and it is expected to obtain ultra-wide-band THz radiation with frequency range from 0.1 THz to 30 THz . In this paper, the experimental results of the bunched mass measurement of multi-pulse ultrashort electron beam are also introduced. The feasibility of generating high-power, tunable quasi-mononuclear THz radiation based on the bunched sequence CTR is verified by simulations. Corresponding experiments Design.