Design considerations for the LCLS

The Linac Coherent Light Source (LCLS) is a single pass X-ray FEL designed to produce very short (∼200 fs) and very high power (8 GW), short wavelength (1.5 Å) pulses. The new facility to be built at SLAC as a multiple laboratory collaboration will have peak brilliance performance exceeding those obtained presently in third generation synchrotron radiation sources by 10 orders of magnitude. In this paper, we review the accelerator physics design challenges. We report on advances made in photo-injectors. We discuss the issues of Coherent Synchrotron Radiation produced in the bunch compressors and undulator vacuum chamber wakefields.