Showing papers by "University of Milano-Bicocca published in 1991"
01 Jul 1991-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, it was shown that the electron phase plane is not that of a pendulum since, besides an elliptic and a hyperbolic pendulum-like fixed point, an extra elliptic point is present at the same phase value as the hyperbola for large enough values of the detuning parameter δ.
Abstract: By a fully Hamiltonian treatment of the FEL dynamics, including the so-called universal scaling, we show that the electron phase plane is never that of a pendulum since, besides an elliptic and a hyperbolic pendulumlike fixed point, an extra elliptic point is present at the same phase value as the hyperbolic one, for large-enough values of the detuning parameter δ. On decreasing δ, these two points get closer, until they collapse at a value of δ which for vanishing initial radiation field coincides with the instability threshold for exponential gain in the many-electron system.
5 citations
TL;DR: In this paper, the one-particle dynamics of a Free Electron Laser (FEL) has been investigated and it has been shown that the electron phase-plane is not that of a pendulum.
3 citations
01 Jul 1991-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, the steady-state and super-radiant regimes of an FEL with a rectangular waveguide for high-gain amplification of microwave radiation were investigated, and it was shown that multimode excitation leads to enhanced peak powers and shortened dynamics also both in strong and in weak superradiance.
Abstract: We investigate many-mode dynamics in the steady-state and superradiant regimes of an FEL with a rectangular waveguide for high-gain amplification of microwave radiation. At steady state a recent many-mode Hamiltonian formulation allows us to derive analytical results for two-mode (TE 01 + TE 21 ) operation, such as the instability threshold for exponential gain, and to explain the main many-mode effects, i.e., higher peak powers, reduced saturation lengths and broader accessible energy ranges, compared with the amplification of the fundamental (TE 01 ) mode alone. Numerical investigation shows that multimode excitation leads to enhanced peak powers and shortened dynamics also both in strong and in weak superradiance. In these regimes, differently from steady-state, the fundamental TE 01 -mode exhibits higher peak powers and efficiencies when higher-order modes are present.
2 citations