Abstract: A plasma burner with microwave stimulation having a cavity of enlarged diameter in the region of the plasma and electrically-conductive windings coaxially encompassing the plasma within the cavity. Said winding render the electrical waveguide system formed by the cavity and windings as coaxial outer guide and the plasma as coaxial inner guide suitable for the transmission of microwaves in said region of the plasma burner in respect of impedance and transmission bandwidth in a particular manner, even with significant pressure variations of the process gas and corresponding variable conductance conditions.

Abstract: An electromagnetic radio-frequency or microwave device having a treatment chamber (6) with a transmission wall (7, 7', 7"), which is permeable for the electromagnetic waves, to an adjacent chamber (4) and with a design of the transmission wall (7, 7', 7") for influencing the intensity distribution of the transmission of the electromagnetic waves into the treatment chamber (6) allows low-loss control of the intensity of the transmitted waves in that the transmission wall (7, 7', 7") has a large number of antenna elements (10, 10') which are directed at an angle to the wall plane of the adjacent chamber (4), are in the form of rods, and project centrally through through-openings (14, 14') which are bounded by electrically conductive material.

Abstract: A gas laser, in particular a CO.sub.2 laser, contains as laser medium a gas that is excited into a plasma by a HF energy supply, in particular a microwave energy supply, whereas the HF waves are coupled into the laser medium (4) through a rectangular waveguide (1). In order to obtain a compact structure with an efficient coupling of the HF energy, coupling is ensured by means of a ribbon-shaped waveguide (3) that projects into the rectangular waveguide (1) and thus also allows the outcoupling on all sides of the rectangular waveguide.