Transport of high-current relativistic electron beams (REBs) in matter is fundamental in high-energy-density physics. However, conventional theories, based on continuum assumptions, fail to describe interactions in disordered porous media, where the beam response to microscopic heterogeneity is nonlinear and collective.
Here, we report the discovery of three distinct transport regimes arising from the interplay between REBs and porous microstructures: Branched flows, where the REB splits into multiple tree-like branches^[1,2]; Super-channeling, where the REB self-organizes into a dense stable and radiating filament^[3]; Anomalous stopping, where low-density porous media stops REBs more effectively than dense solids^[4]. These phenomena share a common origin in the stochastic but correlated multi-kilotesla magnetic fields generated by return currents along the skeletons. Based on these findings, we propose a roadmap to construct a unified phase diagram in the parameter space of beam density, beam energy, and pore size, defining the threshold where high-current effects dominate over collisional ones. These newly identified transport regimes open up promising new avenues for applications in fast ignition, advanced radiation sources, and laboratory astrophysics.

[1] K. Jiang, T. W. Huang, R. Li et al., Phys. Rev. Lett. 130, 185001 (2023).
[2] K. Jiang, T. W. Huang, R. Li et al., Phys. Plasmas 31, 022303 (2024).

relativistic electron beam,porous media,branched flows,super-channeling,anomalous stopping,transport