Bright sources of ultrarelativistic particles and gamma rays for interdisciplinary research

We consider the possibility of generating high-current ultrarelativistic electron beams accelerated in the direct laser acceleration (DLA) regime, and their application in interdisciplinary research. The key approaches are based on the results of simulation and experiments on the interaction of relativistically intense laser pulses with a large-scale plasma of near-critical electron density produced using low-density aerogels. The use of a set of laser pulses from the XCELS will make it possible to achieve the efficiency of the generation of particles (electrons, positrons, protons, and neutrons) and hard gamma radiation in the energy range of tens of MeV, which is orders of magnitude higher than the existing record values.