Nam, S.-K.
(Soon-Kwon Nam)

MOPOS32 Behaviour of Electron Beam in Combined a Self-Generated Field and a Reversed Guide Field in the Helical Wiggler
Soon-Kwon Nam, Ki-Bum Kim (Kangwon National University, Kangwon-Do)

We have studied behaviour of electron beam in combined a self-generated field and a reversed axial-guide field in the tapered helical wiggler. The divergence of electron beam is caused by a three-dimensional effect on the off-axis electrons and self-generated fields. In order to reduce the electron beam loss, we employ a tapered and reversed axial-guide magnetic field. Evolution of energy spread and emittance of electron beam are investigated using three dimensional simulation. Beam cross-section, transverse momentum variation and cross-section view of electron beam are calculated along the z axis. The electron beam loss is reduced by optimizing the magnetic field strength and tapering parameter of reversed axial guide field.

MOPOS33 Evolution of Electron Beam in the Tapered Planar Wiggler
Soon-Kwon Nam, Ki-Bum Kim (Kangwon National University, Kangwon-Do)

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.