HARMONIC GENERATION FOR A HARD XRAY FEL

We present a harmonic generation scheme that is applicable for preseeding a hard x-ray FEL with longitudinally coherent microbunches. In this regime, lasers do not exist even at large subharmonics of the desired bunching, and ISR limits the use of strong magnetic chicanes. Our design uses a combined HGHGEEHG scheme to convert 1 nm microbunches, which are assumed to be generated when the electrons are at a lower energy, to ¼ A microbunches. Here we describe the reasoning behind this design, and show the relevant design parameters and simulation results.