Influence of finite radial geometry on the growth rate of ion-channel free electron laser

Abstract

The influence of finite radial geometry on the instability of a tenuous relativistic electron beam propagating in an ion-channel in a waveguide is investigated. The instability analysis is based on the linearized Vlasov-Maxwell equations for the perturbation about a self-consistent beam equilibrium. With the help of characteristic method the dispersion relation for the TE-mode is derived and analyzed through the numerical solutions. It is found that the positioning of the beam radius Rb relative to the waveguide radius Rc, and the ion-channel frequency can have a large influence on the maximum growth rate and corresponding wave number.

Kinetic description of a free electron laser with an electromagnetic-wave wiggler and ion-channel guiding by using the Einstein coefficient technique

“…The quantum wave kinetic of high-gain FELs has also been calculated by Serbeto et al [17]. The influence of finite radial geometry on the instability of a tenuous relativistic electron beam propagating in an ion-channel in a waveguide is investigated by linearized Vlasov-Maxwell equations [18]. The gain of FEL with a helical wiggler in the presence of a guiding field has also been explained by using the Einstein coefficient method [19][20].…”