Wu, J.

Paper	Title	Page
MO201	Linac Coherent Light Source (LCLS) – Accelerator System Overview	7
	P. Krejcik, Z. Huang, J. Wu SLAC, Menlo Park, California P. Emma SLAC/ARDA, Menlo Park, California
	The Linac Coherent Light Source (LCLS) will be the world's first x-ray free-electron laser (FEL). Pulses of LCLS x-ray FEL will be several orders of magnitude brighter and shorter than most existing sources. These characteristics will enable frontier new science in several areas. To ensure the vitality of FEL lasing, it is critical to preserve the high quality of the electron beam during the acceleration and compression. We will give an overview of the LCLS accelerator system. We will address design essentials and technique challenges to satisfy the FEL requirements. We will report studies on the microbunching instability suppression via a Laser-Heater. The studies clearly prove the necessary of adding the Laser-Heater and show how effectively this Laser-Heater suppresses the instability by enhancing the Landau damping. We will report how to minimize the sensitivity of the final energy spread and the peak current to various system ‘jitters’. To minimize this sensitivity, a feedback system is required together with other diagnostics. With all these considerations, full start-to-end simulations show saturation at 1.5 Å, though the LCLS is expected to be a very challenging machine.
	Transparencies
TUP53	Temporal Profile of the LCLS Photocathode Ultraviolet Drive Laser Tolerated by the Microbunching Instability	390
	J. Wu, Z. Huang SLAC, Menlo Park, California M. Borland ANL, Argonne, Illinois P. Emma SLAC/ARDA, Menlo Park, California C. Limborg SLAC/SSRL, Menlo Park, California
	The high quality LCLS electron beam generated in the photoinjector is subject to all possible instabilities in the downstream acceleration and compression. The instability can be initiated by any possible density modulation of the electron beam when it is generated at the photocathode. In this note, we prescribe the tolerance on the initial electron beam density modulation possibly introduced by the ultraviolet (uv) laser at the cathode. Our study shows that the initial rms density modulation of the electron beam at the photocathode shall be less than 5 % to ensure the FEL lasing and saturation.
TUP54	Resistive-Wall Wake Effect in the Beam Delivery System	393
	J. Wu SLAC, Menlo Park, California J. R. Delayen Jefferson Lab, Newport News, Virginia T.O. Raubenheimer SLAC/NLC, Menlo Park, California J.-M. Wang BNL/NSLS, Upton, Long Island, New York
	The resistive wall instability is investigated in the context of the final beam delivery system of linear colliders. The emittance growth is calculated analytically and compared against the results of full numerical simulations. Criteria for the design of final beam delivery systems are developed.