Generating a quasiellipsoidal electron beam by 3D laser-pulse shaping.

A generic 3D laser-pulse-shaping scheme is proposed towards the generation of a uniform ellipsoidal particle distribution, an ideal distribution due to the linear dependence of the space-charge force on the particle position. The shaping is accomplished via spatiotemporal coupling of the laser dynamics via chromatic aberration in an optical lens. Particle tracking simulations show that the electron beam initiated by such a laser pulse in a high-gradient radio-frequency photoinjector delivers very low emittance, ideal for beam-based light sources such as the x-ray free-electron laser.