ELIXER, a Simulation Code for the Spatial Structure of Light Pulses in Free-Electron Lasers

摘要

This report discusses the simulation code ELIXER, which was developed to studythe spatial evolution of radation in pulsed-beam Free-Electron Lasers. ELIXER includes the full spatial structure of the radiation by means of a set of orthogonal axisymmetric Gauss-Laguerre functions. Reflection and transmission on realistic cavity mirrors is included by means of a matrix formulation. The code differs from other spatially three dimensional models by calculating the longitudinal electron dynamics for each electron separately, whereas the transverse motions are approximated by the variation of the radial beam envelope. This approximation leads to a significant reduction of the numerical effort. An overview of the physical model is presented, and the numerical implementation of the FEL equations in the code is discussed. Particular emphasis is put on the input file, which describes the FEL device that is to be simluated, and on the output files that contain the spatial and spectral properties of the radiation, as well as the energy spectrum of the beam electrons.