Study of the undulator specification for the VUV-FEL at the TESLA test facility

In this paper, the influence of undulator errors, more specific magnetic field errors, on the Free-Electron Laser performance is investigated. Both the influence of variation in undulator peak field and of dipole fields resulting from misaligned quadrupoles, is considered. For these quantities, upper limits are given, and the influence of additional correction stations on the reduction in performance is studied.