Simulation of free-electron lasers in the presence of correlatedmagnetic field errors

The authors address the numerical simulation of field errors that possess statistical correlations. The inevitable errors of actual magnetic wigglers yield a degraded performance of the free-electron laser (FEL) with respect to the performance obtained from ideally modeled magnetic wigglers. The impact of these errors has been theoretically and computationally investigated for simple error modes, in which the field errors have uniform or sinusoidal spatial extent and amplitudes that are statistically independent for each magnet pole piece. These simple models have been recently extended to include more complicated spatial structures and statistically correlated field errors in the analysis of FEL performance. Numerical simulations of the FEL are presented that verify the analytic predictions of the recently extended model