We propose an approach, based on statistical mechanics, to predict the saturated state of a single-pass, high-gain free-electron laser. In analogy with the violent relaxation process in self-gravitating systems and in the Euler equation of two-dimensional turbulence, the initial relaxation of the laser can be described by the statistical mechanics of an associated Vlasov equation. The laser field intensity and the electron bunching parameter reach a quasistationary value which is well fitted by a Vlasov stationary state if the number of electrons N is sufficiently large. Finite N effects (granularity) finally drive the system to Boltzmann-Gibbs statistical equilibrium, but this occurs on times that are unphysical (i.e., excessively long undulators). All theoretical predictions are successfully tested by means of finite-N numerical experiments.
|Titolo:||Statistical theory of high-gain free-electron laser saturation|
|Autori:||J. Barre; T. Dauxois; G. De Ninno; D. Fanelli; S. Ruffo|
|Rivista:||PHYSICAL REVIEW E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS|
|Data di pubblicazione:||2004|
|Digital Object Identifier (DOI):||10.1103/PhysRevE.69.045501|
|Appare nelle tipologie:||1.1 Journal article|