CERN Accelerating science

Article
Report number	SLAC-PUB-10694
Title	Generation of GW-level, sub-Angstrom radiation in the LCLS using a second-harmonic radiator
Author(s)	Huang, Z ; Reiche, S
Affiliation	(SLAC) ; (UCLA)
Publication	2004
Imprint	Aug 2004
Number of pages	5
In:	26th International Free Electron Laser Conference and 11th FEL User Workshop 2004, Trieste, Italy, 29 Aug - 3 Sep 2004, pp.e-proc. MOPOS63
Abstract	Electron beams are strongly microbunched near the high-gain FEL saturation with a rich harmonic content in the beam current. While the coherent harmonic emission is possible in a planar undulator, the third harmonic radiation typically dominates with about 1% of the fundamental power at saturation. In this paper, we discuss the second harmonic emission in the main undulator induced by effects of finite beam size and angular spread. We show that by a suitable design of an second-stage undulator with its fundamental wavelength tuned to the second harmonic of the main undulator, coherent second harmonic radiation much more intense than the third harmonic is emitted. Numerical simulations and applications to the LCLS project aiming at generating GW-level and sub-Angstrom x-ray pulses are presented.

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