Letters to the Editor Quantum theory of SASEFE L

We describe a free-electron laser (FEL) in the Self-Amplified Spontaneous Emission (SASE) regime quantizing the electron motion and taking into account propagation effects. We demonstrate quantum purification of the SASE spectrum, i.e. in a properly defined quantum regime the spiking behavior disappears and the SASEpower spectrum becomes very narrow. r 2005 Elsevier B.V. All rights reserved. PACS: 41.60.Cr; 42.50.Fx