Showing papers by "University of Milano-Bicocca published in 1989"

Simulation of superradiant free-electron lasers

Abstract: It has been suggested that slippage effects in a single-pass free electron laser can generate an output signal near the electron beam tail with a peak amplitude many times greater than the expected saturated value [1]. The growth of such “superradiant” pulses in a helical-wiggler FEL is characterized here using 1-D and 2-D numerical simulations. The 1-D calculations show the effects of detuning, energy spread, and the axial current distribution on superradiant pulses, while preliminary 2-D simulations illustrate the effects of betatron motion and the radial structure of the electron beam.

Tuning and slippage optimization in a high-gain FEL with a waveguide

Abstract: Simple analytical expressions are derived for gain, tuning and slippage of a free electron laser in a waveguide. They exhibit a maximum as a function of the wavelength. At given electron energy and undulator parameters we find that the tuning is optimum at a wavelength λ 1 such that the slippage is zero. It is shown that its value is twice the resonant wavelength λ Γ in vacuum. At λ Γ t slippage is maximum and is half that without waveguide.

Waveguide Effects In Superradiant Free-electron Lasers

Abstract: A quasi-three-dimensional time-dependent particle simulation has been developed to model slippage effects in a single-pass microwave free-electron laser. The code is used here to model the large-amplitude "superradiant" signal that can develop in the slippage region of constant-current beams. Results are presented for single- and multiple-mode cases, and the effects of the waveguide dimensions, detuning, energy spread and the initial power in the modes are discussed.