Concept of a laser-plasma-based electron source for sub-10-fs electron diffraction

We propose a new concept of an electron source for ultrafast electron diffraction with sub-10-fs temporal resolution. Electrons are generated in a laser-plasma accelerator, able to deliver femtosecond electron bunches at 5 MeV energy with a kilohertz repetition rate. The possibility of producing this electron source is demonstrated using particle-in-cell simulations. We then use particle-tracking simulations to show that this electron beam can be transported and manipulated in a realistic beam line, in order to reach parameters suitable for electron diffraction. The beam line consists of realistic static magnetic optics and introduces no temporal jitter. We demonstrate numerically that electron bunches with 5-fs duration and containing 1.5 fC per bunch can be produced, with a transverse coherence length exceeding 2 nm, as required for electron diffraction.