We analyze the dynamics of Free Electron Laser (FEL) devices, operating with a bunched beam exhibiting a longitudinal phase space correlation. We show that the presence of an energy-position correlation term is responsible for very interesting effects like an enhancement of the peak output power, a shortening of the laser pulses and an increase of the non linearly generated harmonic intensities. We conjecture that the mechanism is due to a kind of energy tapering effect associated with the correlation. We discuss the difference of the dynamics with respect to an ordinary undulator tapering and the relative advantages.
@article{arxiv.1011.1341,
title = {Energy Phase Correlation and Pulse Dynamics in Short Bunch High Gain FELs},
author = {G. Dattoli and L. Giannessi and P. L. Ottaviani and S. Pagnutti},
journal= {arXiv preprint arXiv:1011.1341},
year = {2010}
}