3D-SIMULATION OF HIGH-GAIN FELS IN AN OPTICAL KLYSTRON CONFIGURATION

The optical klystron is envisioned as a method of enhancing the free electron laser (FEL) gain as well as a method of obtaining high coherent harmonics. We modify the 3D computer code SHERA to include the capability of calculating FEL performance in the optical klystron configuration. The code includes: (i) energy spread and finite emittance of the electron beam, (ii) diffraction and refraction of the radiation field, and (iii) transverse gradients of the wiggler field. This paper concentrates on the physics of the optical klystron in the high gain limit. We apply this code to evaluate the preliminary FEL design options at the Continuous Electron Beam Accelerator Facility (CEBAF).