Beam Based Alignment of the TESLA X-ray FEL undulators

One of the important parameters that determine the performance of the FEL is the overlap between electron beam and radiation field during the amplification process. An earlier study has shown that in order to maintain this overlap, quadrupoles have to be aligned with an accuracy of 1 m. In addition, first and second field integrals of the magnetic structures have to be corrected. Since this cannot be done by conventional alignment techniques, beam based alignment will be used to determine steerer settings to correct offsets of quadrupoles and first and second magnetic field integrals. In this report, all the steps needed to align the electron beam are discussed. Results of simulations of the final alignment are shown. Parameters that limit the alignment will be addressed.