Experimental Research on Smith-Parcel Free Electron Laser in Millimeter Wave Region

本研究于1995-1996年在毫米波区进行了Smith Purcel自由电子激光器的实验研究。我们工作在1 MV电压下的小型静电加速器(Disktron)。电子源是KrF紫外激光的光电子发射。这种电子源和加速器的组合适用于电子束的精确控制。我们成功地获得了峰值电流1-4A、能量800keV、脉宽30 ns的电子束。这种光束在光束线上传播，光束线由涡流分子泵和低温泵抽真空。利用聚焦磁铁和偏转磁铁对电子束进行了很好的控制，考虑了电子束模式和金属光栅附近电磁波的色散关系，进行了理论分析。设计了理论振荡频率为51 GHz的Smith Purcel自由电子激光器。光栅节距为25 mm，长度为300 mm，利用聚焦磁线圈和偏转线圈控制电子在光栅面附近的传播。我们观察到了来自U波段(45-60 GHz)探测器二极管相互作用区的辐射。二极管接收到的功率接近0dBm。我们将继续进行实验。然而，我们认为我们观察到的是理论预言的51 GHz Smith-Purcel自由电子激光振荡。

The purpose of this research in 1995-1996 is the experimental research on Smith Purcel free electron laser in millimeter wave region.We operated a compact electrostatic accelerator (Disktron) with 1MV voltage. The electron source is photoelectron emission with KrF ultraviolet laser. This conbination of the electron source as well as the accelerator is suitable for precise control of the elctron beam. We successfully obtained the electron beam with 1-4 A peak current, 800KeV energy, and 30ns pulse width. This beam is propageted in the beam line, which is evacuated by a turbmolecular pump and a cryopump. The beam is well controlled by focusing magnets as well as deflection magnets.The theoretical analysis is performed, taking into account the dispersion relation of the electron beam mode and the electromagnetic waves near a metal grating. We design the Smith Purcel free electron laser with theoretical oscillation frequency of 51GHz. The grating pitch is 25mm and the length is 300mm.With aid of the focusing magnetic coils and deflection coils, the electron is carefully controlled to propagate near the grating surface. We observed the radiation from the interaction region with the U band (45-60GHz) detector diode. The power received by the diode is nearly 0dBm.We will continue the experiment. However, we think that what we observe is the 51GHz Smith-Purcel free electron laser oscillation, which is predicted by the theory.