High-gain Compton free electron laser driven by pre-bunched electrons

A theoretical analysis of high-gain Compton free electron laser dynamics when the radio frequency (rf) field evolves self-consistently with single resonant particles representing a pre-bunched electron beam is presented and the single particle phase space is studied. Using a set of universally scaled equations the optimal parameters of excitation for a free electron laser (FEL) in the single particle approximation are found. Using a new approach the relations between the initial rf field amplitude, the output field amplitude and the particle's initial detuning from resonance are also found. A set of equations describing the self-consistent evolution of the rf field with e-bunch macro-parameters, such as bunch width and bunch mean phase, is derived from the universally scaled equations under the condition of the uniform initial distribution of electrons in the bunch. The analysis of optical field generation and amplification by compact bunches of electrons is provided. The saturation regime and the physical reason for the saturation in the high-gain Compton FEL driven by pre-bunched electrons are studied and discussed.