Problem of propagation of an optical discharge near a target

Two-exposure holographic interferometry was used to study the early stages of evolution of a laser plasma near a target as a function of the residual gas (argon and helium) pressures. The distributions of the electron density were calculated and the pressure "breakdown" thresholds were determined for laser intensities of ~10¹¹ W/cm². The conditions for propagation of an optical discharge near a target were analyzed.