CERN Accelerating science

Article
Title	Optical Mode Distortion in a Short Rayleigh Length Free Electron Laser
Author(s)	Blau, Joseph ; Colson, William B ; Mansfield, Robb P ; Niles, Sean P ; Williams, Brett W
Affiliation	(NPS, Monterey, CA)
Publication	2004
In:	26th International Free Electron Laser Conference and 11th FEL User Workshop 2004, Trieste, Italy, 29 Aug - 3 Sep 2004, pp.e-proc. MOPOS66
Subject category	Accelerators and Storage Rings
Abstract	A short-Rayleigh length FEL will operate primarily in the fundamental mode with a Gaussian profile that is narrow at the waist and broad at the mirrors. The gain medium will distort the optical mode profile and produce higher-order modes that will expand more rapidly than the fundamental. Wavefront propagation simulations are used to study the higher-order modes, as the cavity length, Rayleigh length, electron beam current and radius, undulator taper, and the focus positions of the optical mode and electron beam are varied.