E. Gluskin, N.A. VinokurovÝ, G. Decker, R.J. Dejus, P. Emmaý, P. Ilinski, E.R. Moog, H.-D. Nuhný, I.B. Vasserman
Advanced Photon Source, Argonne National Lab, Argonne, IL 60439; Ý Budker Institute of Nuclear Physics,630090 Novosibirsk, Russian Federation; ýStanford Linear Accelerator Center, Stanford, CA 94309
The LCLS undulator line will consist of undulator segments separated by breaks of various lengths. Focusing quadrupoles, in a FODO lattice, and diagnostics will be located in the breaks. The FEL simulation code RON has been used to optimize parameters for the undulator line. The length of the undulators has been varied in order to minimize the overall undulator line length. In this minimization, the effect on beam parameters from the associated change in spacing of the focusing quadrupoles and the distance occupied by the breaks between undulators have been taken into account. The break lengths between undulators have also been optimized and different break lengths after the first three undulators have been found to help reduce the overall undulator line length for saturation. Tolerances for various undulator line magnetic and mechanical parameters have also been investigated using RON. The aligment resulting from a beam-based alignment simulation has been found to increase the overall saturation length by about one gain length as compared to the ideal case.
