CERN Accelerating science

Article
Title	Evolution of Electron Beam in the Tapered Planar Wiggler
Author(s)	Nam, S K ; Kim, Ki Bum
Affiliation	(Kangwon National University, Kangwon-Do)
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. MOPOS33
Subject category	Accelerators and Storage Rings
Abstract	We have investigated the evolution of electron beam in the tapered planar wiggler field with a axial-guide field, self-electric fields, and self-magnetic fields. In order to suppress the divergence of emittance and energy spread of the electron beam by the three-dimensional effects on the off-axis electrons and a self-generated field effect,the wiggler field was tapered and the reversed axial-guide magnetic field was applied. We calculate the emittance, transverse trajectories and Fourier transfomation of electron beam using three dimensional simulation by optimizing the magnetic field strength, a tapering parameter and self-field parameters. This method could be expected to enhance the gain and efficiency compared to those of a uniform axial-guide field and a untapered wiggler in a free-electron laser.