Laser-driven x-ray radiation from nanoarray–gas hybrid plasma target

Betatron oscillations of laser-accelerated electrons in the wakefield can generate ultrafast soft- to hard-x-ray radiation, which has found wide applications in material, biological, and physical sciences. Micro-nano technologies have enabled the creation of micro-undulator arrays that can further enhance the photon energy of x-ray radiation. However, pure nanoarrays usually cannot effectively constrain the electron beam, causing rapid divergence of the latter. Here, we propose an improved scheme to enhance x-ray radiation by utilizing a hybrid target composed of a laser-driven nanoarray and a gas target. The background gas in the hybrid target forms a bubble wakefield, which exerts a focusing effect on the electron beam and thereby maintains the continuous and stable radiation generated by the electrons. Particle-in-cell simulations demonstrate that using the hybrid target yields an x-ray radiation intensity nearly one order of magnitude higher than that of the nanoarray-only target. Further simulation results reveal that this scheme can generate quasi-monochromatic radiation with an energy range of 0.20–1.29 keV by adjusting the electron beam energy. Additionally, the scheme performs well across different energy and angular spreads of the electron beam, making it favorable for practical applications.