Extreme light diagnostics

Generation of high-power short laser pulses of ultra-relativistic intensity (over 10²⁰ W/cm²) with the use of XCELS infrastructure and their application to solve the tasks of laser-plasma interaction and acceleration of charged particles, as well as the tasks of quantum electrodynamics require correct diagnostics of the laser pulse parameters in the interaction region under its sharp focusing. We propose an approach for measuring the key parameters of the XCELS beam, such as its size in the caustic and the peak laser intensity. The proposed method is based on the use of the process of vacuum acceleration of charged particles (electrons and protons) from the focal volume. When using the distribution of the laser pulse fields near its focus, making use of Stratton-Chu diffraction integrals and the test particle method, the characteristics of accelerated electrons and ions can be strictly quantified (for example, the energies of accelerated particles and their escape angles). The latter allows one to offer a practically accessible experimental method for diagnosing the radiation in a single laser shot and a design of XCELS experiment.