Discrete cavity model of a standing-wave free-electron laser

Abstract

A standing-wave free-electron laser (SWFEL) has been proposed for use in a two-beam accelerator (TBA). Unlike a conventional microwave free-electron laser, the SWFEL has a wiggler that is divided by irises into a series of standing-wave cavities, and the beam is reaccelerated by induction cells between cavities. We introduce a one-dimensional discrete-cavity model of the SWFEL. In contrast to the continuum model that has been extensively used to study the device, the new model takes into account time-of-light effects within the cavity and applies the reacceleration field only between cavities, where the ponderomotive force is absent. As in previous SWFEL models, only a single signal frequency is considered. Using this model, effects of finite cavity length are investigated. For moderately long cavities, it is shown that there are no adverse effects on the phase stability of the device.