Bright betatron x-rays generation from picosecond laser interactions with long-scale near critical density plasmas

Our previous experimental and three-dimensional (3D) particle-in-cell (PIC) simulation results demonstrated that a well-directed electron beam with space charge of about mu C and maximum energy of 100MeV can be generated via a sub-petawatt, picosecond laser pulse interacting with a long-scale near-critical-density plasma. Effective laser energy coupling into hot electrons occurs in the presence of strong self-generated quasistatic electric and magnetic fields that confine fast electrons in relativistic ion channels. Here, we report results of 3D PIC simulations, which show that this direct laser accelerated electron beam can work as a compact high-brightness source of x rays. The relativistic electrons make betatron oscillations in the transverse fields of the ion channel and emit a bright broadband x-ray radiation with the critical energy of about 5keV. Due to the huge number of accelerated electrons, our simulation shows that with a picosecond, 20J laser pulse, an x-ray spectrum with a photon number of 7 x 10 11 (>1keV) can be generated, resulting into a peak flux of 2 x 1 0 8 photons/eV and a brilliance of 3.3 x 10 20 photons/s/mm(2)/mrad(2)/0.1%BW.

Automated summary

Through 3D PIC simulations, it is demonstrated that the laser-accelerated electron beam can serve as a compact high-brightness source of X rays. Relativistic electrons undergo betatron oscillations in the ion channel, emitting bright broadband X-ray radiation with a critical energy of about 5keV. The simulation results indicate that with a picosecond, 20J laser pulse, a significant number of photons can be generated, resulting in an X-ray spectrum with high brilliance.