Local beam based alignment procedure for an undulator with superimposed FODO lattice

In order to keep the gain reduction of the TTF VUV-FEL (Conceptual Design Report, Germany, 1995, Ref. [1]) smaller than 15%, the electron beam has to be aligned in the undulator within 12 μm rms. One method of aligning the beam uses the technique of beam-based alignment. In this paper, the applicability region of this method is investigated. The influence of unknown, random dipole kicks due to the error in the planar undulator structure and kicks due to quadrupole offsets are discussed.