Laser wake field acceleration in bubble regime: quasi-monoenergetic electron bunches and flashes of synchrotron radiation

Using our 3D PIC code VLPL (Virtual Laser-Plasma Laboratory) we study Laser-Wake Field Acceleration (LWFA) of electrons by laser pulses shorter than or comparable with the plasma wavelength. When driven into the highly non-linear wave breaking regime the plasma wave mutates to a solitary bubble that generates ultra-short dense bunches of electrons with quasi-monoenergetic energy spectra. The electron bunches may have density high enough to forward-scatter the tail of the laser pulse. The forward scattering results in blue shift of the laser pulse after interaction. The energetic electrons make betatron oscillations in transverse fields of the plasma wave and emit hard X- and γ-rays. We show that an extremely bright source of GeV γ-quanta can be built due to the combination of an external electron beam and the laser wake field. The GeV γ-source can be particularly used as an efficient plant for positron production.