NOVELTY - Flow-through plasma reactor for treating feedstocks at high temperature, comprises: (a) a substantially cylindrical reactor wall having a first closed proximal end and a second open distal end; (b) a second elongated electrode; (c) first and second electrodes further separated by a gap and capable of generating and maintaining a gliding arc plasma discharge within a zone in the reactor upon application of an electric potential difference between the first and second electrodes; (d) cylindrical wall having at least one feedstock injection portal; and (e) cylindrical wall.    USE - The flow-through plasma reactor is useful for treating feedstocks at high temperature (claimed). Preferably, it can be used for reforming high temperature feedstreams into clean synthesis gas, more particularly, for reforming pyrogas using non-thermal plasmas. The produced clean syngas can be efficiently used for power generation in turbines, internal combustion (ICE) engines, (solid oxide) fuel cells or for synthetic liquid fuel production by Fisher-Tropsch process.    ADVANTAGE - The reactor may be added directly in-line with a gas exhaust manifold, and so may be more easily visualized in terms of a flow-through reactor.    DETAILED DESCRIPTION - Flow-through plasma reactor for treating feedstocks at high temperature, comprises: (a) a substantially cylindrical reactor wall having a first closed proximal end and a second open distal end, where portion of the wall is configured to comprise a first electrode; (b) a second elongated electrode, electrically separated from the first electrode by an electrical insulator, the electric insulator forming either part or all of the first closed end of the reactor or positioned proximate to it; (c) first and second electrodes further separated by a gap and capable of generating and maintaining a gliding arc plasma discharge within a zone in the reactor upon application of an electric potential difference between the first and second electrodes; (d) cylindrical wall having at least one feedstock injection portal, the feedstock injection portal capable of sustainably contacting an organic feedstock at the high temperature and configured to direct the feedstock tangentially into the plasma zone of the reactor; and (e) cylindrical wall also having at least one air injection portal. The air injection portal is positioned adjacent to the electrical insulator. The air injection portal is configured to direct air tangentially into the reactor so as to shield the electrical insulator from the high temperature of the feedstock or plasma generated within the reactor, and to generate a vortex flow in the reactor and out the second open end. An INDEPENDENT CLAIM is included for a method of operating the plasma reactor which involves: (a) providing air into the reactor through the air inlet portal at a rate sufficient to maintain the insulator at a temperature below a pre-defined threshold temperature, for example about 500 degrees F (about 260 degrees C); (b) providing feedstock tangentially into the plasma zone through the feedstock inlet portal; and (c) initiating a gliding arc plasma in the plasma zone between the first and second electrodes by the application of an electric potential difference across the first and second electrodes; or a method of operating the plasma reactor which involves (a) providing cooling airflow through the cylindrical annulus; (b) providing the feedstock tangentially into the plasma zone through the feedstock channels; and (c) initiating a gliding arc plasma in the plasma zone between the first and second electrodes by the application of an electric potential difference across the first and second electrodes; or a method of operating the flow-through plasma reactor which involves: (a) passing a high temperature feedstock stream through the reactor; and (b) providing sufficient energy to the at least two non-thermal plasma reactors to provide non-thermal plasma jets into the high temperature feedstock stream; or a method of operating the flow-through plasma reactor which involves: (a) passing a high temperature feedstock stream through the reactor; (b) providing sufficient energy to the at least two non-thermal plasma reactors to provide non-thermal plasma jets into the high temperature feedstock stream; and (c) energizing the blower to blow downstream from the plasma jets so as to reduce the pressure of the feedstock in a volume of the conduit between the at least two non-thermal plasma reactors and the blower, so as to redirect a portion of the gas downstream from the blower to the at least one inlet apparatus of at least one non-thermal plasma reactors.