Laser driven attosecond SASE X-ray FEL

Modern lasers with emission wavelengths ∼1 μm can be used as electromagnetic wigglers and have sufficient output power to obtain wiggler parameters K (normalized vector potential) close to unity. With this kind of wiggler, in order to make a 10-keV X-ray SASE FEL, electron beam energies of ∼25 MeV are sufficient. In this presentation, scaling laws for the operation of FELs will be discussed. Using these scaling laws, requirements for electron sources will be obtained. The required electron beams must be about six orders of magnitude brighter than those available with existing sources. We propose a novel source based on vacuum laser pondermotive acceleration that will produce an electron beam meeting these requirements. This opens up a realistic possibility of realizing the dream of a “table top” X-ray SASE FEL.