基于同轴静磁波荡器的自由电子激光主要利用环形电子束与同轴TE模式的相互作用产生电磁辐射，是一种重要的毫米波辐射源。分析了同轴结构作用区内外半径、工作模式、电子束电压、波荡器周期等参数对辐射频率的影响规律，研究了电子束平均半径的选取原则和束波互作用腔的设计方法，设计了辐射频率在W波段的基于同轴静磁波荡器的自由电子激光，并进行了粒子模拟，在电子束电压为720 kV，电子束流为1 kA的情况下，获得了频率107 GHz、辐射功率35 MW的TE01模，束波转换效率为4.9%，束波作用腔总长度小于200 mm，同轴静磁波荡器的磁场幅度0.34 T。

A free electron laser based on a coaxial static magnetic undulator utilizes annular electron beam interacting with TE mode to coherently generate electromagnetic radiation, which is an important millimeter wave radiation source. The influencing laws of the coaxial inner and outer radii, the operation mode, the beam voltage and the period of the undulator on the radiation frequency are analyzed. The main principles to choose the electron average radius and the designing method of beam-wave interaction cavity are studied. Based on theoretical analysis, a coaxial static magnetic free electron laser at W band is designed and simulated by PIC simulation. The radiation wave at 107 GHz and 35 MW power are acquired. The beam wave power conversation efficiency is 4.9%. The length of the undulator is shorter than 200 mm, and the magnetic field of the undulator is 0.34 T.