Plasma Physics Seminar

The State of the Art in Free-Electron Laser Simulations

Speaker Name: Henry Freund, University of Maryland

Abstract :

Free-electron Lasers have come a long way since the concept was first proposed by Hans Motz in 1950. Early FELs relied on the available accelerator/gun technology and were largely confined to operation in the IR and longer wavelength regimes. However, the development of laser-driven photocathodes permitted the production of extremely low emittance electron beams in RF linacs and has enabled the development of x-ray FELs, which are now under construction around the world. The fundamental theory explaining the operation of FELs was quickly developed and simulations, starting with one-dimensional formulations, were extended to include complete three-dimensional models. Two distinct simulation paths have been followed. One integrates the full 3D Lorentz force equations for the particles and uses a modal superposition for the fields. Another uses a wiggler-averaged orbit analysis in which only two equations are
integrated; specifically, for the particle phase and energy. One- or two-dimensional field solvers are typically used with the wiggler-averaged formulations. In this seminar, I will discuss the basic physics of FELs and then go on to discuss the nonlinear simulation codes that are in use.  Examples showing the level of agreement between the non-wiggler-averaged formulation and experiments will be presented.