Single-mode simulations of a short Rayleigh length FEL

Free electron lasers can make use of a short Rayleigh length optical mode in order to reduce the intensity on resonator mirrors. A simulation method is used that includes the dynamics of this rapidly focusing optical mode and the macroscopic and microscopic electron evolution. The amplitude and phase of the optical fields are represented by a single Gaussian mode. The simulation runs in seconds on small laptop computers and can be used for system analysis.