Visualization and simulation of electron beam transport along a FEL planar wiggler

We have developed and employed a special apparatus for viewing and investigating the motion and behavior of an e-beam inside a planar wiggler. The total current I(z), the current density J(x, y, z), the beam position and cross-section shape were investigated along an evacuated waveguide cavity located on the axis of the wiggler of the TAU 70 KeV FEM. The beam cross-section image could be viewed on the screen through a window at the end of the evacuated waveguide using a CCD camera equipped with a zoom lens. An exact 3D simulation code (PTIMF) developed in our group for simulation of electron trajectories inside and along the wiggler, was used to calculate trajectories of electrons in the wiggler region under conditions similar to those prevailing in the experiment. The correlation of experimental results with those predicted from simulations was good. It is presented and discussed in this paper.