Comparison of wiggler-averaged and non-wiggler-averaged free-electron laser simulations

Two distinct types of free-electron laser simulations are in general use. In “wiggler-averaged” simulation codes such as FRED and TDA, the Lorentz force equations are averaged over a wiggler period. A reduced orbit analysis is obtained requiring integration only of equations for the energy and ponderomotive phase for each electron. In contrast, “non-wiggler-averaged” such as MEDUSA use the complete three-dimensional Lorentz force equations. A direct comparison of the two techniques is discussed in this paper using the MEDUSA and TDA codes.