Well-Collimated Bright Attosecond Dual-Ring-Structured Dense X/ <i>γ</i> -ray Beams Generated by an Intense Vortex Laser

Attosecond light sources are important in science and technology for probing, understanding, and manipulating ultrafast processes such as testing theories of quantum electrodynamics and exploring the limits of light–matter interaction. The current achievable photon energy is limited to the kiloelectron volt level. Here, we present a new scheme for generating energetic donut electron bunches that emit brilliant well-collimated attosecond x/ γ -rays from vortex–laser interaction with rarefied plasma. Self-organized superposition of the laser and its wake electric field results in short dual-ring-structured dense fast-electron bunches. Three-dimensional particle-in-cell simulations show that the latter can emit ultrashort (~420 as), high-flux (&gt;10 12 photons per pulse), well-collimated (divergence angle &lt; 10°), and ultrabrilliant (up to 2.23 × 10 25 photons s −1 mm −2 mrad −2 per 0.1% bandwidth at 1-MeV photon energy) gamma rays.