The design of a small compact pulsed blowdown apparatus coupled to a cold cathode electron gun is described. This system allows the excitation of a gas mixture in supersonic flow at temperatures of 80 and 120 K and density of 1 amagat with a maximum electron beam current density of 20 A cm−2at 300 kV and pulse length of 0.5 &mgr;s. With this facility it has been possible, using aerodynamic cooling, to achieve high‐power, long‐pulse ultraviolet laser operation in a high‐pressure active medium on XeF and Ne iiion transitions. A strong increase in fluorescence intensity was also obtained for numerous atomic lines and molecular bands of interest for the developement of high‐power, high‐efficiency, visible and ultraviolet lasers.