A plasma generating system includes a waveguide for transmitting a microwave energy therethrough and an inner wall disposed within the waveguide to define a plasma cavity, where a plasma is generated within the plasma cavity using the microwave energy. The plasma generating system further includes: an adaptor having a gas outlet through which an exhaust gas processed by the plasma exits the plasma cavity; and a recuperator directly attached to the adaptor and having a gas passageway that is in fluid communication with the gas outlet in the adaptor. The recuperator recovers heat energy from the exhaust gas and heats an input gas using the heat energy.