Abstract: High power microwave plasma torch. The torch includes a source of microwave energy which is propagated by a waveguide. The waveguide has no structural restrictions between the source of microwave energy and the plasma to effect resonance. The gas flows across the waveguide and microwave energy is coupled into the gas to create a plasma. At least 5 kilowatts of microwave energy is coupled into the gas. It is preferred that the waveguide be a fundamental mode waveguide or a quasi-optical overmoded waveguide. In one embodiment, the plasma torch is used in a furnace for heating a material within the furnace.