Electrons Trajectories in Electromagnetically Pumped Free Electron Laser with a Constant Reverse Guide Magnetic Field

An exact solution to the quartic equation in the wiggler frequency ωw , which represents the dispersion
relation for this system, is obtained. The effects of the frequency of the wiggler ωw on the electron’s velocities
(v|| and vw) are investigated. The regions of interest for the allowed wiggler frequency ωw for both group
I and group II electron trajectories are discussed.