Investigation of Electron Beam Parameter in Seeded THz-FEL Amplifier using Photocathode RF Gun

Simple, compact, and powerful seeded terahertz-free electron laser (THz-FEL) which consists of a photocathode radio-frequency gun, a focusing solenoid, an undulator and a THz wave parametric generator has been designed. A start-to-end calculation has been performed by using the particle tracking code PARMELA and the FEL gain simulation code GENESIS1.3. To obtain a higher FEL gain, we searched a better condition of the electron beam parameter and the seed light. In the present design scheme, the FEL peak power was calculated to be 3 kW at the FEL resonant wavelength of 179 m. Since the power of the seed light was 0.20 W, the light power was amplified almost 104 times.