Self-consistent nonlinear simulations of high-power free-electron lasers

Two 3-D nonlinear formulations of FEL amplifiers are described which treat both planar and helical wiggler geometries. For convenience, we refer to the planar (helical) formulation and simulation code as WIGGLIN (ARACHNE). These formulations are slow-time-scale models for FEL amplifiers in which the electron dynamics are treated using the complete 3-D Lorentz force equations without recourse to a wiggler period average. The application of these codes to the description of a collective reversed-field FEL experiment and to random wiggler field errors is described.