High-flux and bright betatron X-ray source generated from femtosecond laser pulse interaction with sub-critical...

Recent progress on betatron X-ray source enables the exploration of new physics in fundamental science; however, the application range is still limited by the source flux and brightness. In this Letter, we show the generation of more than 1 × 10¹² photons (energy > 1 keV) with a peak brightness of 7.8 × 10²² photons/(s mm² mrad²) at 0.1% bandwidth (BW) at 10 keV, driven by a femtosecond laser pulse of ≈5.5 J and a sub-critical density plasma (SCDP). The source flux is more than two orders of magnitude higher than that from typical laser wakefield electron acceleration. This method to produce high-flux and bright X-ray source would open a wide range of applications.