Multidimensional simulation studies of the SELENE FEL oscillator/buncher followed by a radiator/amplifier output scheme

Abstract

We analyze and present numerical simulations of the so-called electron output scheme applied to the SELENE proposal of using a high power FEL to illuminate satellite solar cells. In this scheme, a first stage FEL oscillator bunches the electron beam while a second stage `radiator' extracts high power radiation. Our analysis suggests only in the case where the radiator employs a long, tapered undulator will the electron output scheme produce a significant increase in extraction efficiency over what is obtainable from a simple, single-stage oscillator, 1- and 2-D numerical simulations of a 1.7 μm FEL employing the electron output scheme show that large bunching fractions at the output of the oscillator stage but only approximately 1% extraction efficiency from the radiator stage.