High-contrast energy modulation of electron beams for improved microbunching and coherence of free-electron radiation sources

High-contrast energy modulation (HCM) of high-brightness electron bunches, made possible by recent experimental or conceptual advancements in ultra-short-pulse terawatt IR/visible/UV laser and storage ring-based insertion device technologies, makes it possible to consider schemes for generating ultra-short radiation pulses based on the highly non-linear bunching induced by the modulation. In prior publications, the single-particle interaction with the laser and insertion device fields was analyzed and shown to lead to the appropriate initial conditions for bunching. In the present paper we report on continuing studies of the collective (i.e., multi-particle) dynamics of the modulated bunch region. In addition, we describe preliminary analyses that indicate that the coherent power generated by HCM sources could be made comparable to or greater than that of corresponding single-pass, gain-saturated Free Electron Lasers (FELs). Selected differences between the dynamics and performance of conventional high-harmonic FELs and Optical Klystrons (OKs) and the analyzed high-contrast modulation/bunching system are discussed. Some possible applications of HCM to the flexible tailoring of particle beam phase space parameters are mentioned.