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

1995-1996年的研究目的是对Smith Purcel自由电子激光器在毫米波区域的实验研究。我们操作了一个1MV电压的紧凑型静电加速器（Disktron）。电子源为KrF紫外激光器的光电子发射。电子源和加速器的这种组合适合于电子束的精确控制。我们成功地获得了峰值电流为1-4 A，能量为800KeV，脉冲宽度为30ns的电子束。该光束在由湍流分子泵和低温泵抽真空的束流线上传播。通过聚焦磁铁和偏转磁铁可以很好地控制光束。考虑到电子束模式与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51GHz的Smith Purcel自由电子激光器。光栅间距25mm，长度300mm。借助聚焦磁线圈和偏转线圈，电子被小心地控制在光栅表面附近传播。我们观察了与U波段（45-60GHz）探测器二极管相互作用区域的辐射。二极管接收的功率接近0dBm。我们将继续实验。然而，我们认为我们观察到的是51GHz的Smith-Purcel自由电子激光振荡，这是理论所预测的。

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.