Development of Infrared Free-Electron Lasers with High-Brightness Electron Beams

1.在自由电子激光器（FEL）的放大实验中，在波长20和40 μ m处观察到了高亮度单束光束的自放大自发辐射。辐射的特性已经测量出来了。通过改变每束电子的电荷，研究了放大的基本过程。我们还成功地产生了高亮度的双束电子束，在光学谐振器的配置下，通过两倍放大可以产生高功率的自由电子束流。对多束光束的特性进行了测量。经放大后，在40 μ m共振波长处的自发发射强度约为非相干发射强度的3倍。光学腔内共振作用下的放大现象至今尚未观察到。利用低发射度电子枪改善了光束的质量，这将有力地改善振荡器实验的条件。自由电子激光器光源的研制红外自由电子激光器的脉冲宽度估计为20ps。用黑体光源和波动器的辐射对探测器的光灵敏度进行了评估。建立了加速器室辐射向外传输系统和检测系统。

1.Amplifier FELIn free-electron laser (FEL) amplifier experiments self-amplified spontaneous emission from a high brightness single-bunch beam has been observed at wavelengths of 20 and 40 mum. The characteristics of the radiation have been measured. The fundamental processes of the amplification have been investigated by changing the charge of electrons per bunch. We also have succeeded in the generation of high-brightness two-bunch electron beams which possibly generate high-power FEL by twice amplification under the configuration of an optical resonator.2. Oscillator FELThe characteristics of the multibunch beams have been measured. The intensity of the spontaneous emission at a resonant wavelength of 40 mum has been found to be about three times of that of the incoherent emission after amplification. The amplification under resonance in the optical cavity has not been observed so far. The quality of the beam has been improved by using a low-emittance electron gun, which would strongly improve the conditions for the oscillator experiments.3.Development of a FEL light sourceThe pulse width of the infrared FEL is estimated to be 20 ps. The sensitivity of the detector of light has been evaluated with a blackbody light source and the radiation from an undulator. The transport system of the radiation from the accelerator room to outside and the detection system have been established.