Analysis of the formation of the active medium of a λ = 15.5-nm plasma laser pumped by a CO2 laser

A numerical analysis is made of the dynamics of formation of a laser plasma having parameters necessary for efficient amplification due to the n = 4 → n = 3 transition in hydrogen-like sodium ions. By selecting an initial target density substantially lower than that of a solid, the requirements for the input energy can be reduced. For example, for a plasma cylinder of 0.1-mm initial radius and a density of 10¹⁹–10²⁰ cm^–3, an energy of 5–10 J/cm deposited within ~1 nsec is sufficient to achieve a gain higher than 1 cm^–1.