Simulations of a klystron undulator for the SLAC X-ray FEL

The Stanford Linear Accelerator Center (SLAC) linac has been proposed as an electron beam source for a high power X-ray FEL. A klystron design with an enclosed dispersive section allows a shorter undulator to achieve bunching in a weak radiation field. Single-mode phase-space simulations are used to investigate the effectiveness of electron bunching and the onset of saturation. A longitudinal multimode simulation shows the resulting coherence development.