SOLEIL, Gif-sur-Yvette
PhLAM/CERCLA, Villeneuve d'Ascq Cedex
LAL, Orsay
University of Erlangen-Nuremberg, Erlangen-Nuremberg
We investigate a dynamical behaviors occurring in single-pass free electron lasers (FELs), depending on the electron beam, undulator and seed laser parameters. We put in evidence a complex spatiotemporal deformation of the amplified pulse, leading ultimately to a pulse splitting effect with two sub-pulses. This phenomenon has been first observed in PERSEO simulations in the case of ARC-EN-CIEL project studies, and then been analyzed more in details with the Colson-Bonifacio FEL equations. This studies reveal that slippage length as well as the seed laser pulse wings are the main ingredients of this dynamics [1]. We show that the splitting results from the nonhomogeneous saturation of the gain by the optical field copropagating with the electron beam.
M.Labat et al. “Pulse-splitting in short wavelength seeded free electron laser,” Phys. Rev. Lett. {10}3, 264801 (2009)
