title: Suppression of the pulsed regimes appearing in free-electron lasers using feedback control of an unstable stationary state.
abstract: We show that the pulsed regimes observed in free-electron lasers (FELs) can be suppressed using feedback control. By applying tiny parameter perturbations, the feedback allows to keep the systems onto a stationary state that is naturally existing in phase space, but is usually inaccessible because of its unstable nature. We test this method numerically on a master equation derived from the classical iterative model. Then we present the experimental results obtained on the super-ACO FEL. This method is in principle directly applicable to the other free-electron lasers, whose instabilities have a dynamical (deterministic) origin.
authors.affiliation: Laboratoire de Physique des Lasers, Atomes et Molécules, UMR CNRS 8523, Centre d'Etudes et de Recherches Lasers et Applications, FR CNRS 2416, Université des Sciences et Technologies de Lille, F-59655 Villeneuve d'Ascq Cedex, France.
authors.forename: S
authors.initials: S
authors.lastname: Bielawski
authors.forename: C
authors.initials: C
authors.lastname: Bruni
authors.forename: G L
authors.initials: GL
authors.lastname: Orlandi
authors.forename: D
authors.initials: D
authors.lastname: Garzella
authors.forename: M E
authors.initials: ME
authors.lastname: Couprie