Abstract: A device for coupling microwave energy with at least one exciter, and for distributing it therealong for the purpose of producing a plasma, includes a first enclosure whose inside is bathed in microwave energy, a second enclosure containing a gaseous medium to be ionized, and a first series of at least one communication passage between the two enclosures. An exciter is mounted to pass through each communication passage at a distance from the inside surfaces and to extend into the first and second enclosures in order to couple with a portion of the microwave energy and convey the coupled microwave energy locally into association with the gaseous medium. The exciter constitutes, together with the passage and portions of the sidewalls of the enclosures facing the exciter, a coaxial-type structure.