plasma gas treatment device

This plasma gas treatment device, maintained by microwaves comprises a hollow structure (12) forming a waveguide intended to be connected to a microwave generator, and means (29) for circulating the gas treated through the said structure in a region (20) in which the amplitude of the electric field associated with the incident wave is high. The means for circulating the gas comprises a torch (29) to plasma for producing a plasma in the gas. The torch comprises a nozzle (30) of electrically conductive material mounted on a first large face (33A) of said structure (12) and projecting through an orifice made in a second large face (33B) opposite to said first large face. A gap for passage of the incident waves extending around the injector.