Wu, J.

Paper	Title	Page
WG313	Beam Physics Highlights of the FERMI@ELETTRA Project	27
	S. Di Mitri, M. Cornacchia, P. Craievich, G. Penco, M. Trovo ELETTRA, Basovizza, Trieste P. Emma, Z. Huang, J. Wu SLAC, Menlo Park, California D. Wang MIT, Middleton, Massachusetts A. Zholents LBNL, Berkeley, California
	The electron beam dynamics in the Fermi Linac has been studied in the framework of the design of a single-pass free electron laser (fel) based on a seeded harmonic cascade. The wakefields of some accelerating sections represent a challenge for the preservation of a small beam emittance and for achieving a small final energy spread. Various analytical techniques and tracking codes have been employed in order to minimize the quadratic and the cubic energy chirps in the longitudinal phase space, since they may cause a degradation of the fel bandwidth. As for the transverse motion, the beam breakup (bbu) instability has been recognized as the main source of emittance dilution; the simulations show the validity of local and non-local correction methods in order to counteract the typical “banana” shape distortion of the beam caused by the instability.
	Slides
WG502	Feedback Concepts: Experience at SPPS, LCLS Plans
	P. Krejcik, S. Allison, P. Emma, D. Fairley, J. Wu SLAC, Menlo Park, California
	The LCLS will operate with single bunches at a repetition rate of 120 Hz. The control system is designed to measure and respond to beam errors within the 8.3 ms between pulses. Single-shot, high-resolution measurements of the beam position are required for trajectory feedback control as well as beam energy control in the bunch compressor chicanes and dog-leg beam lines. A single-shot measurement of the bunch length at the exit of bunch compressor chicanes is also required to provide full feedback control of the longitudinal phase space. The amplitude and phases of linac klystrons are controlled pulse-by-pulse within one global feedback loop to maintain the correct energy and bunch length of the beam. The bunch length is determined from measurements of the coherent radiation of the beam, but the type of detector employed varies with bunch length at each location and hence wavelength of the coherent radiation. Experience has been gained with single-shot pyroelectric detectors at the SLAC Sub-Picosecond Pulsed Source (SPPS) and simple feedback control was implemented to stabilize the bunch length. The plans for implementing a full feedback system at LCLS will also be presented.
	Slides