Bright Sources of Ultrarelativistic Particles and Gamma Rays for Interdisciplinary Research

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