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| WG502 |
Feedback Concepts: Experience at SPPS, LCLS Plans
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- P. Krejcik, S. Allison, P. Emma, D. Fairley, J. Wu
SLAC, Menlo Park, California
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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.
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Slides
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