Generation of relativistic electrons via interaction between 12 TW laser pulse and supersonic gas jet

We have studied generation of relativistic electrons by interaction between a high intensity ultra-short laser pulse (Ti:Sapphire, 12 TW, 50 fs, λ=790 nm) and gas jet as a basic research of high performance compact electron accelerators. In the experiment, spatial and energy distribution of energetic electrons produced by an ultra-short, intense laser pulse in a He gas jet are measured. They depend strongly on the laser pre-pulse condition. In the case of a proper pre-pulse the electrons are injected at the shock front produced by the pre-pulse and accelerated by consequent plasma wake-field up to tens MeV forming a narrow-coned ejection angle. The numerical analysis based on a 2D hydrodynamics (for the laser pre-pulse) and 2D particle-in-cell (PIC) simulation justify the mechanism of electron injection and acceleration. (author)