Seeding and harmonic generation in free-electron lasers

Abstract

We review the main seeded FEL configurations with particular emphasis on the high-gain harmonic generation. We derive the equations for the growth of the power starting from a pre-bunched beam and provide a simple method to predict the power performances of a seeded free-electron laser device. The formalism introduced may be extended and used in the analysis of other features of a seeded FEL, as the pulse length and saturation effects.