Effects of Metal Mirrors Reflectivity and Aberrations on THz FEL Radiation Performance

The primary design study of a terahertz free-electron laser (FEL) is presented in this paper. The effects of optical cavity parameter, metal mirrors reflectivity and aberrations on the THz FEL radiation performance have been explored. The reflectivity characteristics of copper, silver and gold are tested in terahertz region. The effects of metal mirrors reflectivity and aberrations on the THz FEL radiation performance are studied by numerical simulation. INTRODUCTION An RF-linac based terahertz FEL oscillator is proposed by Huazhong University of Science and Technology, which is considered to produce 60-150 m terahertz radiation. It is necessary to optimize the strength of the fundamental FEL coupling by choosing basic parameters to maximize the small signal gain parameter. And other parameters should be optimized to minimise the gain degradation. The electron beam quality and undulator properties needed for a THz FEL oscillator have been explored in references [1, 2]. The effects of optical cavity parameter, metal mirrors reflectivity and aberrations on the THz FEL radiation performance are focused in this paper. The main design parameters are listed in Table 1. Table 1: Design Parameters of the THz-FEL Oscillator