Controlled Betatron radiation from high-charge electron beams in multiple plasma channels

We propose what we believe is a novel approach for generating intense Betatron radiation in multiple plasma channels induced by the interference of two relativistic, intense laser pulses in near-critical density plasma (NCDP). Our method uses particle-in-cell (PIC) simulations to explore the effects of cross-propagating laser pulses at specific angles as they overlap in the NCDP. This overlap leads to the formation of a strong transverse standing wave, resulting in spatially periodic plasma channels. Compared to the conventional single-channel structure formed by a single laser beam, multiple plasma channels enable more efficient Betatron radiation generation. Three-dimensional (3D) PIC simulations show that over 0.8 µC of electrons can be accelerated to a maximum energy of 300 MeV when two femtosecond, 56 J laser pulses interact with NCDP at an angle of 5^∘. This setup generates an X-ray spectrum with a photon number of 1.8 × 10¹³(>1keV) and a peak flux of 5.8 × 10⁸ photons/0.1%BW. To further investigate the formation of the Betatron electron oscillations, additional PIC simulations are conducted to examine the dependence on various laser parameters. Overall, our proposed method provides a promising and controlled mechanism for creating novel X-ray sources with desirable properties such as compact size, high efficiency, and tunable spectral characteristics.