Numerical Simulation of a Hybrid Undulator Applied in THz Radiation Source

Abstract: 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.