Laser assisted emittance exchange: Downsizing the x-ray free electron laser

Abstract

A technique is proposed to generate electron beam with ultralow transverse emittance through laser assisted transverse-to-longitudinal emittance exchange. In the scheme a laser operating in the TEM10 mode is used to interact with the electron beam in a dispersive region and to initiate the emittance exchange. It is shown that with the proposed technique one can significantly downsize an x-ray free electron laser (FEL), which may greatly extend the availability of these light sources. A hard x-ray FEL operating at 1.5 Å with a saturation length within 30 meters using a 3.8 GeV electron beam is shown to be practically feasible. © 2010 The American Physical Society.