Abstract: A device (2; 2I; 2II; 2IV; 2V; 2VI; 2VII; 2VIII) for generating plasma and for directing an electron beam towards a target (3); the device (2; 2I; 2II; 2IV; 2V; 2VI; 2VII; 2VIII) comprises a hollow element (5); an activation group (21), which is designed to impose a difference in potential between the hollow element (5) and another element which is separate from it, in such a way as to direct the electron beam towards said separate element; and a de Laval nozzle (23), having at least one tapered portion (13), which is tapered towards the separate element and is designed to accelerate a gas flow towards the separate element.