摘要
The undulator is the key component in the compact THz radiation source based on FEL.By matching the adjustable period magnetic field of the undulator with the optical resonance cavity,the passing electron beam will generate coherent radiation with gain,and the radiation power required by THz source can be achieved finally. Compared with the pure permanent magnet type,the hybrid type undulator can decrease the field errors caused by non-homogeneous magnetization of magnetic blocks,and provide higher magnetic field.The conceptual design of a hybrid undulator used for THz radiation source is introduced.We use the FEM code OPERA/TOSCA to simulate 3D magnetic field of the undulator.After optimizing the end structure of the hybrid undulator,the first field integrals is controlled within 0.01Gs.m,and the deviation of the electron beam is less than 0.02mm.
波荡器是基于自由电子激光的小型THz源关键器件,其可调节的周期性磁场结构与两端的光腔配合,使得穿越的电子束产生带增益的相干辐射,最终达到THz源所需要的功率.同纯永磁结构相比,混合型波荡器通过软铁材料调节由永磁块磁化方向性差异导致的磁场分布误差,同时可提供更高的场强.本文针对小型THz源需求,对混合型波荡器进行了相关物理设计.在解析方法分析的基础上,采用OPERA3D/TOSCA有限元分析软件,对波荡器进行了三维磁场数值模拟和积分场优化.通过对波荡器端部结构的调整,优化后模型的一次场积分(导向误差)小于0.01Gs·m,电子轨迹偏移小于0.02mm.
