Ultrashort-duration relativistic electron beam accelerated by an intense laser

The self-modulated laser wakefield regime, where the laser pulse duration is much longer than a plasma period is discussed. The plasma wave was measured with Thomson scattering to have a duration of 1.5 ps or plasma periods. The electron acceleration beyond the current limitation of laser-plasma accelerators are also demonstrated. To create monoenergetic femtosecond electron bunches, a new concept for laser injection of electrons using the plasma itself as the cathode is also discussed. It is shown by use of a 2-D particle-in-cell numerical code that it will produce 2-fs electronbunches with energy spread at the percent level.