Abstract <p>We presented the design of an all-metal atmospheric pressure microwave plasma torch that does not require the use of a dielectric discharge chamber separating the discharge region from the region where microwave energy is supplied to it. The basis of the plasma torch design is a section of a round waveguide short-circuited at both ends. The connection distance of the feeding rectangular waveguide to one of its ends is selected based on the condition of maximum matching at the operating frequency; at its second short-circuited end, a section of the cutoff circular waveguide is axially located. When conditions for the occurrence of a microwave discharge are created in the latter, the transverse waveguide becomes “enlightened” and is transformed into a coaxial broadband waveguide, the internal conductor of which is an extended plasma discharge, supported and fed by microwave energy coming from the main circular waveguide.</p>