Influence of the refractive index and composition of the active mixture on the radiation divergence of an electron-beam-controlled СО2 laser

An experimental investigation was made of the influence of the refractive index and composition of the active mixture on the divergence of radiation from an atmospheric-pressure electron-beam-controlled СО₂ laser pumped by 30-μs pulses. The change in the СО₂ refractive index within the gain profile of the laser transition was estimated. A mixture with a 75% He content and a СО₂/N₂ concentration ratio of 1–2 ensured the lowest divergence.