Microwave plasma torch and method of use thereof
地域：
North York
摘要
A microwave plasma torch and a method of use thereof is provided. The microwave plasma torch includes a torch housing, a microwave generator, at least one conductive rod, and a waveguide housing. The torch housing includes an outlet and at least one inlet that is positioned for injecting at least one plasma-forming gas. The conical chamber section within the torch chamber is shaped to accelerate the flow of the plasma-forming gas and produce a vortex flow pattern. The microwave generator produces a microwave signal and an electromagnetic field which is directed to the torch chamber by the waveguide housing. The at least one conductive rod is energized for applying a charge to the plasma-forming gas and generating a plurality of plasma streamers. The generated plasma streamers further ionize the plasma-forming gas to generate a plasma stream.
說明書
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The present disclosure relates generally to plasma generation systems. In particular, the disclosure relates to a microwave plasma torch and a method of use thereof.
In a microwave plasma system, the electromagnetic wave is generated by the magnetron with high frequency and transferred to the quartz tube (discharge chamber) by the waveguide. The electric field causes acceleration of the electrons and generates a plasma discharge inside the quartz tube. The magnetic field creates the motion of the electrons inside the plasma helically, which is suitable where the loss of the electrons will be the minimum. The electromagnetic wave does not disperse inside the plasma volume; it only diffuses for a small distance from the surface, i.e., the current passing through the surface of the plasma; this is called skin depth, and the thickness of the skin depth is inversely proportional to the frequency of the source.
The gas breakdown depends on the working pressure in the AC plasma discharge. In the case of atmospheric plasma discharge, a high electric field is needed to start the gas discharge. The mean free path of the electrons that starts the discharge is small, and the electrons cannot gain enough energy from the electric field to ionize the gas atoms/molecules. In the microwave plasma discharge, Because of the high mobility of the electrons, they can flow the electric field, while the ions do not move and do not involve in the plasma discharge. So, reducing the loss of electrons from the plasma during the discharge is essential to keep the plasma working.
While microwave plasma systems are well established, there are several existing issues with these conventional microwave plasma systems.
權(quán)利要求
What is claimed is:1. A microwave plasma torch comprising:a torch housing that defines a torch chamber therewithin, and that includes at least one inlet that is positioned for injecting at least one plasma-forming gas along an inner wall of the torch chamber, tangential to the inner wall of the torch chamber, the torch chamber including at least one cylindrical chamber section and a conical chamber section extending from the at least one cylindrical chamber section, the conical chamber section being shaped to accelerate a flow of the at least one plasma-forming gas along a length thereof for producing a vortex flow pattern of the at least one plasma-forming gas within the torch chamber; a microwave generator for generating a microwave signal and an electromagnetic field; at least one conductive rod that is disposed within the torch chamber; and a waveguide housing including a first waveguide end that is connected to the microwave generator and a second waveguide end that is connected to the torch housing, the waveguide housing being shaped to direct the electromagnetic field and the microwave signal from the microwave generator into the torch chamber for energizing the at least one conductive rod; wherein the at least one conductive rod is mounted within the torch chamber such that the at least one conductive rod is within a path of the electromagnetic field as the electromagnetic field is directed into the torch chamber; wherein the at least one conductive rod is energized via the electromagnetic field for applying a charge to the at least one plasma-forming gas for generating a plurality of plasma streamers from the at least one plasma-forming gas; and wherein the plurality of plasma streamers generated from the at least one plasma-forming gas are structured as a plurality of ionization fronts of the at least one plasma forming gas which further ionize the at least one plasma-forming gas to generate a plasma stream therefrom. 2. The microwave plasma torch of claim 1 , wherein the inner wall of the torch chamber along which the at least one plasma-forming gas is injected is an inner wall of the at least one cylindrical chamber section. 3. The microwave plasma torch of claim 2 , wherein the at least one cylindrical chamber section includes a first cylindrical chamber section and a second cylindrical chamber section disposed between the first cylindrical chamber section and the conical chamber section, and wherein a diameter of the first cylindrical chamber section is less than a diameter of the second cylindrical chamber section. 4. The microwave plasma torch of claim 3 , wherein the at least one gas inlet is positioned within the torch housing such that the at least one plasma-forming gas is injected into the first cylindrical chamber section of the at least one cylindrical chamber section. 5. The microwave plasma torch of claim 4 , wherein the second waveguide end surrounds a portion of the torch housing. 6. The microwave plasma torch of claim 5 , wherein the portion of the torch housing that is surrounded by the second waveguide end is the second cylindrical chamber section. 7. The microwave plasma torch of claim 6 , wherein the conical chamber section is formed with a taper such that a diameter of the conical chamber section adjacent the at least one cylindrical chamber section is greater than a diameter of the conical chamber section adjacent an outlet of the torch housing. 8. The microwave plasma torch of claim 7 , wherein the conductive rod includes a conductive rod tip, and wherein the conductive rod is positioned within the torch chamber such that the conductive rod tip is disposed within the at least one cylindrical chamber section. 9. The microwave plasma torch of claim 8 , wherein a long axis of the conductive rod is aligned to be parallel to an electric field portion of the electromagnetic field within the torch chamber. 10. The microwave plasma torch of claim 1 , wherein the torch housing is composed of at least one dielectric material. 11. The microwave plasma torch of claim 1 , wherein the microwave generator is any one of a magnetron and a solid-state power amplifier (SSPA). 12. A microwave plasma torch comprising:a torch housing that defines a torch chamber therewithin, and that includes at least one gas inlet for the injection of at least one plasma forming gas and an outlet for expelling a plasma stream generated from the at least one plasma-forming gas; a conductive rod that is mounted within the torch chamber such that a tip of the conductive rod is disposed within a discharge portion of the torch chamber; a microwave generator for generating an electromagnetic field and a microwave signal; and a waveguide housing including a first waveguide end that is connected to the microwave generator and a second waveguide end which surrounds a length of the torch housing that includes the discharge portion of the torch chamber, the waveguide housing being shaped to direct the electromagnetic field and the microwave signal from the microwave generator to the torch chamber within the torch housing for energizing the at least one conductive rod; wherein the at least one conductive rod is mounted within the torch chamber such that the at least one conductive rod is within a path of the electromagnetic field as the electromagnetic field is directed into the torch chamber; wherein the energizing of the at least one conductive rod ionizes the at least one plasma-forming gas to drive the formation of a plurality of plasma streamers within the torch chamber; and wherein the plurality of plasma streamers are structured as a plurality of ionization fronts of the at least one plasma forming gas which further ionize the at least one plasma-forming gas to generate a flow of plasma therefrom. 13. The microwave plasma torch of claim 12 , wherein the inner wall of the torch chamber along which the at least one plasma-forming gas is injected is an inner wall of the discharge portion. 14. The microwave plasma torch of claim 13 , wherein the waveguide housing is composed of any one of a plastic material, a metal material with a low bulk resistivity, and a metal material with low conductivity characteristics. 15. The microwave plasma torch of claim 12 , wherein the torch housing is at least partially composed of at least one dielectric material. 16. The microwave plasma torch of claim 15 , wherein the torch chamber includes at least one cylindrical chamber section and a conical chamber section extending between the at least one cylindrical chamber section and the outlet of the torch chamber and wherein the discharge portion is formed within the at least one cylindrical chamber section, and the at least one conductive rod is concentrically mounted within the at least one cylindrical chamber section. 17. The microwave plasma torch of claim 16 , wherein the at least one conductive rod includes a conductive rod tip, and wherein the at least one conductive rod is positioned within the torch chamber such that the conductive rod tip is disposed within the at least one cylindrical chamber section. 18. The microwave plasma torch of claim 17 wherein a long axis of the at least one conductive rod is aligned to be parallel to an electric field portion of the electromagnetic field within the torch chamber. 19. The microwave plasma torch of claim 15 , wherein the chamber includes at least one cylindrical chamber section and a conical chamber section extending between the at least one cylindrical chamber section and the outlet of the torch chamber, and wherein the conical chamber section is shaped to accelerate a flow of the at least one plasma-forming gas along a length thereof for producing a vortex flow of the at least one plasma-forming gas within the torch chamber. 20. The microwave plasma torch of claim 19 , wherein the conical chamber section is shaped with a taper such that a diameter of the conical chamber section adjacent the at least one cylindrical chamber section is greater than a diameter of the conical chamber section adjacent the outlet of the torch housing. 21. The microwave plasma torch of claim 12 , wherein the microwave generator is any one of a magnetron and a solid-state power amplifier (SSPA).
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