High-density thick-beam free-electron laser.

Abstract

A free-electron laser, which employs a high-density thick electron beam, of a thickness comparable to the wiggler wavelength, is considered. Full transverse dependence of the wiggler field as well as equilibrium self-fields of the beam are taken into account. We identify a domain in parameter space where the electron beam is wholly resonant and the gain scales as in the one-dimensional theory of the free-electron laser in the Raman regime. A family of electron-density radial profiles is shown to have a low shear in the resonance parameter and thus to exhibit a particularly high gain.