FEL dynamics, electron-beam bunching and prebunching

We discuss how a prebunched beam may modify the dynamical behavior of a free-electron laser. We show that the lowest-order coefficients b_1,2, modify the small signal dynamics, while the saturated regime is affected by the higher-order coefficients. We also present an analysis of the interplay between bunching, saturation and higher harmonic emission during the FEL evolution.