3D MULTI-FREQUENCY FEL SIMULATIONS WITH THE GENERAL PARTICLE TRACER CODE

The 3D General Particle Tracer (GPT) code has been extended to perform multi-frequency multi-pass free-electron laser (FEL) simulations. The new model is based on axisymmetric multiple Gaussian waves propagating in free space, without averaging over the undulator period. The field equations are integrated simultaneously with the equations of motion of the particles, making the model ideally suited to calculate electron beam phase-space distributions during and after FEL interaction. Due to the from-first-principles approach of the model, it is useful to a variety of radiation problems. The model and a proof-of-principle test are presented.