中文摘要：

在FEL实验中，电子束通过摇摆器，一方面由于周期性磁场作用，电子束轨迹要周期性的摆动，另一方面还要辐射同FEL辐射波长一致的自发辐射，该辐射谱反映电子束、摇摆器集成后的参数。在CAEP（Institute of China Academic Engineering Physics）远红外100μmFEL实验中，自发辐射谱通过Ge：Ga低温探头和远红外100μm光栅谱仪测量。文章侧重从实际摇摆器磁场分析了远红外100μmFEL的自发辐射谱。

英文摘要：

In the FEL experiment, when electron beam passes through the wiggler, the movement of electron beam will be changed to wiggle in the wiggler due to the periodical magnet field. Meanwhile the electron beam will spontaneously emit the radiation with a wavelength similiar to the FEL radiation. This radiation is influenced by the parameters of both the electron beam and the wiggler. The gain of FEL was determined by the spontaneous emission spectrometer, and the spectrum width mainly determined by the periods of wiggler and electron energy homogeneity （ΔE/E）. According to the measured parameters of electron beam and the wiggler, the spontaneous emission was studied. In the experiment, the spectrum of the spontaneous emis sion was measured by far infrared 100μm spectrometer with Ge ： Ga detector.