Measurement of an electron bunch and establishment of the intense mm wave light source with the coherent radiation

高能短电子束的相干辐射在亚毫米至毫米波长范围内具有连续光谱。本文利用相干辐射建立了一种新的高亮度毫米波光源。用干涉仪和远红外探测器、硅辐射热计测量了ISIR电子直线加速器强光束的相干跃迁辐射光谱。根据结果对电子束形状进行了评价。建立了电子束形状精细结构的监测系统。对直线加速器的运行条件进行了优化，以获得稳定的强辐射。相干跃迁辐射已经从加速器室传送出去了。这是第一个用光栅谱仪建立的吸收光谱系统。辐射的峰值和平均功率分别比其他光源高5个数量级和1个数量级以上。强光源可用于强吸收物质的吸收光谱和非线性效应的研究。对远红外光谱的标准材料N_2O气体进行了吸收光谱分析。对吸收量大的水样也进行了测量，并对温度依赖性进行了研究。波长分辨率为1%。这是用光栅光谱仪首次得到的结果。还进行了脉冲辐射分解实验。展望了该光源的广泛应用前景。

The coherent radiation from high-energy short electron bunches has a continuous spectrum in a submillimeter to millimeter wavelength range. In this work a new high-brightness millimeter wave light source has been established by using the coherent radiation.The spectra of the coherent transition radiation from the intense beam of the ISIR electron linac have been measured with an interferometer and far-infrared light detectors, silicon bolometers. The electron bunch shape has been evaluated from the results. The monitoring system for the fine structure of the electron bunch shape has been established. The operational conditions of the linac have been optimized so as to obtain stable and intense radiation. The coherent transition radiation has been transported out from the accelerator room. This is the first system established for the absorption spectroscopy with a grating spectrometer.The peak and the averaged power of the radiation are more than five and more than one order of magnitude higher than those of the other light sources, respectively. The intense light source can be applied to the absorption spectroscopy of matters with relatively strong absorption and to investigating nonlinear effects.Absorption spectroscopy has been performed for N_2O gas, which is a standard material for the far-infrared spectroscopy. Measurements have been also carried out for water samples having strong absorption and the temperature dependence has been investigated. The wavelength resolution is 1%. These are the first results which have been obtained by using a grating spectrometer. Pulse radiolysis experiments have been also performed. The future wide-range applications of the light source are expected.