Plasma generator

A plasma generator (1) comprising a main duct (10) for a gas to be ionised (20), a waveguide (50) for electromagnetic radiation (30), and at least one supporting element (60) on which the waveguide (50) and main duct (10) are mounted; a first portion (51) of the waveguide (50) extends transversely of the supporting element (60) in a first region (61a) facing a first surface (61) of the supporting element. A second portion (52) of the waveguide (50) intersects the duct (10) for interaction between the gas (20) and the radiation (30) and for plasma generation (40); the duct (10) expends transversely of the supporting element (60) in the first region (61a).