Abstract: A method and an apparatus for preionizing a lasing gas mixture in a gas discharge laser. A short pulse of ionizing particles, such as electrons produced by an electron beam are beamed from the electron source, through a window and into the laser container to preionize a gas mixture containing CO.sub.2, N.sub.2, and He. Immediately after the gas mixture has been preionized, the discharge voltage is raised from a sustaining level to a discharge-maintaining level. The gas mixture can be maintained in its excited state for an extended time, and a longer pulse of laser light results. The electron beam and the discharge voltage can be coordinated by a control system connected to the high voltage sources used to produce the electron beam and the gas discharge.