Generation of harmonic radiation using the multi-cavity free-electron laser.

摘要

An FEL provides a convenient method of reaching short wavelengths by resonating with an input source at the fundamental wavelength while providing bunching at a harmonic of the fundamental. Recently schemes have been proposed that use two wiggler segments, one resonant at the fundamental to pre-bunch the beam, the other lasing at the desired (third) harmonic. A similar effect, with some advantages and some disadvantages, can be achieved using the Multi-Cavity FEL (MC/FEL). The MC/FEL employs several short cavities, operating in an oscillator-like manner, to achieve high output power. In this paper we consider the use of the MC/FEL as a means of generating harmonics. We investigate the competitiveness of this option in comparison with other harmonic generation schemes, in terms of the total wiggler length needed, the saturated power achieved, and the restrictions imposed by mirror reflectivity.