Abstract: A gas-jet ejector has an inlet chamber designed to be connected to an evacuated space, a mixing chamber and a diffuser communicating with a vacuum pump which are all series-arranged in a direction coinciding with the direction of gas flow and in alignment with each other inside a housing. A Laval nozzle connected to the surroundings is contained inside the inlet chamber in alignment therewith. The geometry of the critical section of the Laval nozzle, its outflow section and the inlet and outlet sections of the mixing chamber is conducive to increasing the volumetric flow rate across the outlet section of the diffuser 1.35 to 1.80 times.