Circularly polarized x-ray generation from an ionization induced laser plasma electron accelerator

A laser plasma accelerator could provide high-intensity x-ray radiation as the basis for the next generation compact radiation source. However, there is still a lack of tunability for the radiation polarization, especially the circular polarization. Here, we propose a new method for achieving intense circularly polarized x-rays via circularly polarized 20 TW laser pulses driving plasma wakefield acceleration in the regime of ionization injection. When the laser pulse duration is long enough, the ionization injected electrons would not only possess angular momentum, but also be resonant with the laser pulses, resulting in helix structure trajectories in the process of acceleration. In our simulation, we acquired synchrotron radiation with the circularly polarized degree Pc ∼ 0.8, the pulse duration ∼16 fs, the energy spectrum peak ∼1 keV and the brilliance ∼1.8 × 1020 photons s−1 mm−2 mrad−2/0.1%BW. Such an ultra-fast and ultra-brilliant circularly polarized x-ray source has excellent application prospects in the analysis of complex bio-macro-molecule structures and for probing warm dense matter.