Gamma rays, defined as photons with energies exceeding 100 keV, find extensive applications across multiple scientific domains including laboratory astrophysics, high-energy-density physics, strong-field quantum electrodynamics research. While conventional generation methods require large accelerators, laser-driven interaction between relativistic electron beams and matter shows promise through bremsstrahlung processes.  Current implementations, however, suffer from suboptimal energy conversion efficiency.
We found a simple compact scheme for generating extremely brilliant energetic gamma rays, namely from REB propagating through a disordered porous material (e.g., low-density foam). Instead of being randomly scattered or branched off, the REB self-organizes into a dense filament and remains stable as it propagates through the randomly distributed pore-and-skeleton structures. We term this unexpected process super-channeling, since the REB is not confined directly by regular potential channels as it in periodic magnetic undulator or its analogy, but rather indirectly and more subtly by virtual and dynamical channel in randomly uneven and long-range correlated magnetic fields generated in the pores. As the REB filament executes tight betatron oscillations in the magnetic channel, collimated energetic gamma photons are efficiently emitted. Three-dimensional (3D) particle-in-cell (PIC) simulations demonstrate that using the available REBs from laser plasma accelerator or linear accelerator, gamma rays with peak brilliance 10²⁷ photons s^-1mm^-2mrad^-2 per 0.1% bandwidth, photon energy over several GeV, and beam-to-photon energy conversion efficiency over 40%, can be produced. These attributes are several orders of magnitude greater than that from existing gamma ray schemes, paving the way to facilitate bright high-energy gamma rays across diverse fields of science and technology.
 

electron beam,gamma ray,porous foam,radiation