Microwave plasma torch that induces discharge gas swirl into the center of the discharge tube

Abstract

A microwave plasma torch is disclosed. The microwave plasma torch comprises: a rectangular waveguide for transmitting electromagnetic waves; a discharge tube having a cylindrical shape, including a swirl guide shield formed at one end of the cylindrical shape with an inclination toward the central axis of the cylindrical shape as it moves away from the one end, and a plasma discharge port on the opposite side of the swirl guide shield, wherein the space between the swirl guide shield and the plasma discharge port is vertically penetrated by the rectangular waveguide to allow electromagnetic waves to flow into the interior; and a plurality of discharge gas injectors installed tangentially to the discharge tube from the direction of the plasma discharge port to inject discharge gas into the interior of the discharge tube as a swirl, wherein the discharge gas is injected as a swirl along the inner wall of the discharge tube toward the swirl guide shield, and then moves toward the plasma discharge port as a swirl that narrows the radius of rotation while in contact with the inclined inner surface of the swirl guide shield, thereby more narrowly surrounding the center of the discharge tube.

Description

Technology Field

[0001] The present invention relates to a microwave plasma torch, and more specifically, to a microwave plasma torch capable of concentrating a discharge gas injected into a discharge tube at the center of the discharge tube. Background Technology

[0002] A microwave plasma torch is a device that generates plasma using microwaves.

[0003] In a microwave plasma torch, microwaves generated by a magnetron are transmitted through a waveguide to a discharge tube that penetrates vertically through the waveguide. A discharge gas, such as argon (Ar), nitrogen (N2), or oxygen (O2), is injected into the discharge tube. As the microwaves pass through the discharge gas, they cause electrons to vibrate and induce collisions, thereby ionizing them. The ionized gas then transforms into a plasma state to generate plasma.

[0004] These microwave plasma torches are usefully utilized for semiconductor etching, thin film deposition, metal cutting / welding, waste plasma treatment, plasma modification (e.g., powder processing, hydrogen production), etc.

[0005] Meanwhile, in a microwave plasma torch, the electric field peak (E-field) of the microwaves transmitted to the discharge tube is located at the center of the tube; consequently, the plasma generated within the tube exhibits the highest temperature and density at the center. Relatively speaking, the temperature decreases and the density is reduced towards the inner wall of the discharge tube.

[0006] When plasma modification is performed using such a microwave plasma torch, it is most efficient to perform the modification at the center of the discharge tube, whereas the modification efficiency decreases when the modification is performed towards the inner wall of the discharge tube.

[0007] For example, in the case of powder processing for powder modification (e.g., surface modification), when powder is injected into the interior of a discharge tube, the powder is distributed toward the center and inner wall of the discharge tube, making it difficult to achieve efficient processing of the entire injected powder.

[0008] As another example, when injecting methane into a discharge tube for the thermal decomposition of methane to generate hydrogen, the methane is typically injected from the side of the discharge tube. In such cases, the methane is thermally decomposed toward the inner wall of the discharge tube, which not only reduces thermal decomposition efficiency but also causes solid particles (carbon) to be generated during decomposition and deposited on the inner wall. This obstructs the transmission of microwaves into the interior of the discharge tube, making it difficult to generate plasma. The problem to be solved

[0009] Therefore, the problem that the present invention aims to solve is to provide a microwave plasma torch in which the plasma density can be further increased at the center of the discharge tube, and the contact time with the inner wall of the discharge tube can be relatively shortened compared to the case where the discharge gas is continuously in contact with the inside of the discharge tube.

[0010] For another purpose, the invention provides a microwave plasma torch that minimizes the contact time with the inner wall of the discharge tube when processing reactive gases such as methane, allows for thermal decomposition at a reduced rate in the center of the discharge tube so that sufficient thermal decomposition can occur in the center where the plasma temperature is high, and resolves the difficulty of plasma formation caused by the deposition of solid particles on the inner wall of the discharge tube.

[0011] Another objective is to provide a microwave plasma torch that increases the modification efficiency of a gas or powder to be modified by exposing the gas or material to be modified to a high-temperature plasma at the center of the discharge tube during plasma treatment of the gas or powder to be modified. means of solving the problem

[0012] A microwave plasma torch according to one embodiment of the present invention comprises: a rectangular waveguide for transmitting electromagnetic waves; a discharge tube having a cylindrical shape, including a swirl guide shield formed at one end of the cylindrical shape with an inclination toward the central axis of the cylindrical shape as it moves away from the one end, and a plasma discharge port on the opposite side of the swirl guide shield, wherein the space between the swirl guide shield and the plasma discharge port is vertically penetrated by the rectangular waveguide to allow electromagnetic waves to flow into the interior; and a plurality of discharge gas injectors installed tangentially to the discharge tube from the direction of the plasma discharge port to inject discharge gas into the interior of the discharge tube as a swirl, wherein the discharge gas is injected as a swirl along the inner wall of the discharge tube toward the swirl guide shield, and then moves toward the plasma discharge port as a swirl that narrows the radius of rotation while in contact with the inclined inner surface of the swirl guide shield, thereby more narrowly surrounding the center of the discharge tube.

[0013] In one embodiment, the portion of the discharge tube penetrating the right-angle waveguide may be a dielectric, and the swirl guide shield may be made of a metal material.

[0014] In one embodiment, the dielectric may be quartz.

[0015] In one embodiment, the plurality of discharge gas inlets may be installed in the tangential direction and inclined upward at a certain angle.

[0016] In one embodiment, the inclination angle of the plurality of discharge gas inlets may be 45 degrees or more and 90 degrees or less.

[0017] In one embodiment, the discharge tube further includes a central penetration port through which a gas or material to be processed is introduced by penetrating the center of a swirl guide shielding portion coaxial with the central axis of the cylindrical shape, and the material to be processed can be processed while passing through the inner swirl that more narrowly surrounds the center of the discharge tube.

[0018] In one embodiment, the discharge tube includes a central swirl guide tube of dielectric material provided in its inner center, and the central swirl guide tube is provided with a diameter such that its outer surface is spaced apart from the inner surface of the discharge tube, wherein the diameter is capable of accommodating a swirl that more narrowly surrounds the center of the discharge tube, and the end of the central swirl guide tube facing the swirl guide shield is spaced apart from the inner surface of the swirl guide shield, and the swirl that more narrowly surrounds the center of the discharge tube and the gas or material to be treated can be guided and moved toward the plasma discharge port along the inner passage of the central swirl guide tube.

[0019] In one embodiment, the central swirl guide tube may be formed such that its diameter decreases as it moves from the end facing the swirl guide shielding part toward the opposite direction.

[0020] In one embodiment, the central swirl guide tube includes a plasma central target swirl guide inside, and the plasma central target swirl guide may be formed such that one end is connected to the end facing the swirl guide shield of the central swirl guide tube and the diameter decreases as it moves in the opposite direction from the end facing the swirl guide shield.

[0021] In one embodiment, the swirl guide shield may be dome-shaped.

[0022] In one embodiment, the swirl guide shield may have a triangular pyramid shape.

[0023] In one embodiment, the device may further include a cylindrical cooling jacket that encloses a portion of the discharge tube exposed to the outside of the right-angle waveguide; a cooling water inlet penetrating the side of the cooling jacket at one end of the cooling jacket; and a cooling water outlet penetrating the side of the cooling jacket at the opposite side of the location of the cooling water inlet. Effects of the invention

[0024] The microwave plasma torch according to the present invention has the following advantages.

[0025] First, since the discharge gas is discharged toward the plasma outlet while concentrated in the center of the discharge tube, the plasma density in the center of the discharge tube can be further increased, and the contact time with the inner wall of the discharge tube can be relatively shortened compared to the case where the discharge gas is in continuous contact with the inside of the discharge tube.

[0026] Second, when processing reactive gases such as methane, the contact time with the inner wall of the discharge tube is minimized, and thermal decomposition occurs at a reduced rate in the center of the discharge tube, allowing sufficient thermal decomposition to take place in the center where the plasma temperature is high, thereby resolving the difficulty of plasma formation caused by the deposition of solid particles on the inner wall of the discharge tube.

[0027] Third, when plasma treating a gas or powder to be treated that requires modification, the gas or material to be treated is exposed to high-temperature plasma at the center of the discharge tube, thereby increasing the modification efficiency of the gas or material to be treated.

[0028] Fourth, there is an advantage in that reactive gases such as methane can be further guided toward the center of the plasma to come into contact with a higher temperature plasma, thereby increasing the thermal decomposition efficiency by the plasma. Brief explanation of the drawing

[0029] FIG. 1 is a diagram showing the configuration of a microwave plasma torch according to one embodiment of the present invention. Figure 2 is a drawing showing a transverse cross-sectional view of the discharge tube illustrated in Figure 1. Figure 3 is a drawing showing a plurality of discharge gas inlets shown in Figure 1 installed tangentially to a discharge tube. Figure 4 is a diagram showing the results of computational fluid dynamics (CFD) simulations to verify the velocity distribution of the discharge gas in each of Examples 1 to 3. Figure 5 is a diagram showing the results of computational fluid dynamics (CFD) simulations to verify the pressure distribution of the discharge gas in each of Examples 1 to 3. FIG. 6 is a drawing illustrating a microwave plasma torch according to another embodiment of the present invention. FIG. 7 is a drawing illustrating a microwave plasma torch according to another embodiment of the present invention. FIG. 8 is a drawing illustrating a microwave plasma torch according to another embodiment of the present invention. Specific details for implementing the invention

[0030] Hereinafter, a microwave plasma torch according to an embodiment of the present invention will be described in detail with reference to the attached drawings. Since the present invention is susceptible to various modifications and may take various forms, specific embodiments are illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to the specific disclosed forms, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the present invention. Similar reference numerals have been used for similar components in the description of each drawing. In the attached drawings, the dimensions of the structures are shown enlarged compared to the actual dimensions for the clarity of the present invention.

[0031] Terms such as "first," "second," etc., may be used to describe various components, but said components should not be limited by said terms. These terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be named the second component, and similarly, the second component may be named the first component.

[0032] The terms used in this application are used merely to describe specific embodiments and are not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, terms such as "comprising" or "having" are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0033] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application.

[0034] FIG. 1 is a diagram showing the configuration of a microwave plasma torch according to one embodiment of the present invention.

[0035] Referring to FIG. 1, a microwave plasma torch according to one embodiment of the present invention may include a right-angle waveguide (100), a discharge tube (200), and a plurality of discharge gas inlets (300).

[0036] The rectangular waveguide (100) is a dominant mode waveguide, and TE 10 It is a mode waveguide and transmits electromagnetic waves at a frequency of 2.45 GHz.

[0037] The discharge tube (200) is cylindrical in shape and provides a space in which plasma is generated by electromagnetic waves input into the right-angle waveguide (100) by vertically penetrating the right-angle waveguide (100) from the end of the right-angle waveguide (100). At this time, the discharge tube (200) may be positioned at a λ / 4 position from the end of the right-angle waveguide (100). In this case, the maximum peak of the electromagnetic waves input into the discharge tube (200) may be at the center of the discharge tube (200).

[0038] The discharge tube (200) includes a swirl guide shielding section (310) and a plasma discharge port (320) opposite the swirl guide shielding section (310), and is installed so that electromagnetic waves are introduced into the interior by vertically penetrating the right-angle waveguide (100) between the swirl guide shielding section (310) and the plasma discharge port (320).

[0039] The swirl guide shield (310) may be formed at one end of the cylindrical shape of the discharge tube (200) to have an inclined path facing the central axis of the cylindrical shape as it moves away from the one end. For example, the swirl guide shield (310) may be dome-shaped.

[0040] In one embodiment, the discharge tube (200) may have a dielectric material in the part penetrating the right-angle waveguide (100), and the swirl guide shield (310) may be made of a metal material.

[0041] For example, the dielectric material may be quartz, and the metal material may be SUS.

[0042] For example, the space between the swirl guide shield (310) and the plasma discharge port (320) may be made of quartz, and a portion of the length in the direction of the swirl guide shield (310) and the plasma discharge port (320) may be made of metal.

[0043] For example, the discharge tube (200) may have an inner diameter within the range of 28 to 32 mm, and the distance from the end of the plasma discharge port (320) to the center of the swirl guide shield (310) may be within the range of 100 to 200 mm.

[0044] A plurality of discharge gas inlets (300) are installed tangentially to the discharge tube in the direction of the plasma discharge port (320) to inject discharge gas into the interior of the discharge tube in a swirl.

[0045] In one embodiment, a plurality of discharge gas inlets (300) may be installed in the tangential direction and inclined upward at a certain angle. For example, the inclination angle of the plurality of discharge gas inlets (300) may be 45 degrees or more and 90 degrees or less.

[0046] In a microwave plasma torch according to one embodiment of the present invention, electromagnetic waves transmitted through a right-angle waveguide (100) penetrate vertically through the right-angle waveguide (100) and are input into the interior of the discharge tube (200) through a portion of the dielectric material of the discharge tube (200), for example, quartz, which is opposed to the electromagnetic waves, and at this time, the electromagnetic waves exhibit a maximum peak at the center of the discharge tube (200).

[0047] In this manner, with electromagnetic waves input into the discharge tube (200), the discharge gas is injected tangentially into the discharge tube (200) through a plurality of discharge gas inlets (300) from the direction of the plasma discharge port (320) of the discharge tube (200) to form a swirl, and moves toward the swirl guide shielding part (310) along the longitudinal direction of the discharge tube (200) while forming plasma inside the discharge tube (200). The discharge gas reaching the swirl guide shielding part (310) comes into contact with the inner curved surface of the swirl guide shielding part (310), and moves toward the plasma discharge port (320) as a swirl (hereinafter referred to as reverse swirl) that more narrowly surrounds the center of the discharge tube (200).

[0048] Accordingly, the discharge gas moves toward the plasma outlet (320) by forming a reverse swirl that is concentrated at the center of the discharge tube (200) where the maximum peak of the electromagnetic wave is distributed. Therefore, during the process of plasma discharge, the discharge gas is discharged toward the plasma outlet (320) from the center of the discharge tube (200) which is spaced apart from the inner wall of the discharge tube (200) without continuously contacting the inner wall of the discharge tube (200). Since the discharge gas is discharged toward the plasma outlet (320) in a state where the plasma temperature is highest at the center of the discharge tube (200) according to the maximum peak of the electromagnetic wave, the plasma density at the center of the discharge tube (200) can be further increased, and the time of contact with the inner wall of the discharge tube (200) can be shortened relatively compared to the case where the discharge gas is continuously in contact with the inside of the discharge tube (200).

[0049] Example 1

[0050] A discharge tube (200) was manufactured with a length of 100 mm and an inner diameter of 28 mm, and a plurality of discharge gas inlets (300) were installed at a 45-degree angle tangential to the discharge tube (200) and had a diameter of 3 mm, and methane was injected as the discharge gas.

[0051] Example 2

[0052] The length and inner diameter of the discharge tube (200) were manufactured to be the same as in Example 1, and a plurality of discharge gas inlets (300) were arranged to be the same as in Example 1 but installed to have a diameter of 3.5 mm, and methane was injected as the discharge gas.

[0053] Example 3

[0054] The length and inner diameter of the discharge tube (200) were manufactured to be the same as in Example 1, and a plurality of discharge gas inlets (300) were arranged to be the same as in Example 1 but installed to have a diameter of 4 mm, and methane was injected as the discharge gas.

[0055] FIG. 4 is a diagram showing the results of a computational fluid dynamics (CFD) simulation to verify the velocity distribution of the discharge gas in each of Examples 1 to 3, and FIG. 5 is a diagram showing the results of a computational fluid dynamics (CFD) simulation to verify the pressure distribution of the discharge gas in each of Examples 1 to 3.

[0056] As shown in Fig. 4, it was confirmed that in all Examples 1 to 3, the velocity of the discharge gas was fast at the inner wall of the discharge tube, and the velocity decreased when moving in a swirl from the center of the discharge tube while in contact with the dome-shaped end of the discharge tube.

[0057] In addition, as shown in Fig. 5, it was confirmed that a pressure distribution of the discharge gas was formed in the center of the discharge tube in all of Examples 1 to 3.

[0058] Accordingly, for example, when methane (CH4) is injected as the discharge gas of a microwave plasma torch according to one embodiment of the present invention, the discharge gas moves at a high speed as it travels along the inner wall of the discharge tube (200) in a swirl, and when it comes into contact with the dome-shaped end, it forms a reverse swirl and its speed decreases as it moves in the center of the discharge tube, so that it is thermally decomposed by the plasma. Therefore, the time of contact with the inner wall of the discharge tube is minimized, and since it is thermally decomposed at a reduced speed in the center of the discharge tube (200), sufficient thermal decomposition can be achieved in the center where the plasma temperature is high, and the phenomenon of solid particles being deposited on the inner wall of the discharge tube (200) is prevented, so that interference with electromagnetic wave input into the discharge tube (200) does not occur, thus resolving the difficulty of plasma formation caused by the deposition of solid particles on the inner wall of the discharge tube (200).

[0059] Meanwhile, a microwave plasma torch according to one embodiment of the present invention may further include a cooling jacket (410), a cooling water inlet (420), and a cooling water outlet (430).

[0060] The cooling jacket (410) can cover a portion of the discharge tube (200) that is exposed to the outside of the right-angle waveguide (100). For example, the cooling jacket (410) may be provided with an internal space in a double-tube structure to allow for cooling water circulation, and may be installed to cover a portion of the length of the discharge tube (200) in the direction of the swirl guide shield (310).

[0061] The coolant inlet (420) can penetrate the side of the cooling jacket (410) from the direction of one end of the cooling jacket (410) and can inject coolant into the interior of the cooling jacket (410). For example, the coolant inlet (420) can penetrate the side from the bottom of the cooling jacket (410).

[0062] The coolant outlet (430) may penetrate the side of the cooling jacket (410) on the opposite side of the location of the coolant inlet (420), and the coolant traveling along the longitudinal direction of the cooling jacket (410) may be discharged. For example, the coolant outlet (430) may penetrate the side of the cooling jacket (410) from the top.

[0063] Cooling water injected into the cooling jacket (410) through the cooling water inlet (420) is injected at a constant pressure and undergoes a circulation process in which it fills the inside of the cooling jacket (410) and is discharged through the cooling water outlet (430). Through this circulation of cooling water, the discharge tube (200) surrounded by the cooling jacket (410) can be cooled, and accordingly, the overheating of the discharge tube (200) caused by high-temperature plasma can be prevented, thereby extending the lifespan of the discharge tube (200).

[0064] Meanwhile, a microwave plasma torch according to one embodiment of the present invention may further include a central through-inlet (500) and a central swirl guide (600) provided at the center of the discharge tube (200).

[0065] The central through-inlet (500) penetrates from the end of the dome shape to the center of the dome shape, allowing a gas to be processed or a material to be processed to be introduced. In the case of a gas to be processed, it can be injected at a constant pressure and injected along the longitudinal direction from the center of the discharge tube (200), and in the case of a material to be processed, it can be free-falling from the center of the discharge tube (200). For example, the gas to be processed may be waste gas requiring modification, and the material to be processed may be a powder requiring modification. The powder may be a powder of carbon, alumina, metal, etc.

[0066] Additional gas for efficient plasma discharge within the discharge tube (200) may be injected through the central through-hole inlet (500). For example, if a reactive gas such as methane is injected through a plurality of discharge gas inlets (300), additional gas that is relatively advantageous for plasma discharge, such as an inert gas, may be injected.

[0067] The center swirl guide (600) is cylindrical and is provided with a diameter such that its outer surface is spaced apart from the inner surface of the discharge tube (200) at the inner center of the discharge tube (200), and the diameter may be a diameter capable of accommodating a swirl (reverse swirl) that more narrowly surrounds the center of the discharge tube (200), and the end of the center swirl guide (600) facing the swirl guide shield (310) may be spaced apart from the inner surface of the swirl guide shield (310).

[0068] For example, the center swirl guide (600) can be connected to the inner surface of the discharge tube (200) through a rod or bar-type connector and positioned at the center of the discharge tube (200).

[0069] This central swirl guide (600) can stably guide the initial swirl of the discharge gas moving along the inner wall of the discharge tube (200) to the swirl guide shield (310). That is, when the swirl of the discharge gas moves toward the swirl guide shield (310), the speed may decrease as it moves further away from the multiple discharge gas inlets (300), but since it is guided while passing between the outer surface of the central swirl guide (600) and the inner wall of the discharge tube (200), the speed is not reduced and dispersed, and it can move stably to the swirl guide shield (310).

[0070] Additionally, a discharge gas moving in a reverse swirl enters the center swirl guide (600) and is guided along the longitudinal direction of the center swirl guide (600), thereby trapping the discharge gas moving in a reverse swirl so that plasma can be concentrated within the center swirl guide (600), and a gas or material to be processed injected through the center through-hole (500) can also be introduced into the center swirl guide (600) and moved along the longitudinal direction of the center swirl guide (600) while being exposed to high-temperature plasma to be processed.

[0071] Accordingly, in a microwave plasma torch according to one embodiment of the present invention, high-temperature plasma can be further concentrated in the center of the discharge tube (200), and since the gas or material to be treated is exposed to the high-temperature plasma in the center of the discharge tube (200) for treatment, the modification efficiency of the gas or material to be treated can be increased.

[0072] FIG. 6 is a drawing illustrating a microwave plasma torch according to another embodiment of the present invention.

[0073] Referring to FIG. 6, the microwave plasma torch according to another embodiment of the present invention is identical to the microwave plasma torch according to one embodiment of the present invention except that the swirl guide shielding part (310) of the discharge tube (200) is in the shape of a triangular pyramid, so further detailed description is omitted.

[0074] FIG. 7 is a drawing illustrating a microwave plasma torch according to another embodiment of the present invention.

[0075] Referring to FIG. 7, a microwave plasma torch according to another embodiment of the present invention is identical to a microwave plasma torch according to one embodiment of the present invention, except that the swirl guide shielding portion (310) of the discharge tube (200) is dome-shaped and the central swirl guide (600) is formed such that its diameter decreases as it goes from the end facing the swirl guide shielding portion (310) of the discharge tube (200) toward the opposite direction.

[0076] As the diameter of the central swirl guide (600) decreases from the end facing the swirl guide shield (310) toward the opposite direction, the reverse swirl entering the central swirl guide (600) is further guided toward the center of the plasma, and accordingly, the discharge gas moving in the reverse swirl comes into contact with the plasma at a higher temperature, and for example, if the discharge gas is methane, the thermal decomposition efficiency by the plasma can be increased.

[0077] FIG. 8 is a drawing illustrating a microwave plasma torch according to another embodiment of the present invention.

[0078] Referring to FIG. 8, the microwave plasma torch according to another embodiment of the present invention is identical to the microwave plasma torch according to one embodiment of the present invention except that the swirl guide shielding part (310) of the discharge tube (200) is in the shape of a triangular pyramid and the center swirl guide (600) includes a plasma center target swirl guide (700) inside it; therefore, the following description will focus on the plasma center target swirl guide (700).

[0079] A plasma center target swirl guide (700) can be formed such that one end is connected to the end facing the swirl guide shield (310) of the center swirl guide (600), and the diameter decreases as it moves in the opposite direction from the end facing the swirl guide shield (310).

[0080] In a microwave plasma torch according to another embodiment of the present invention, the swirl of the initial discharge gas can move stably toward the swirl guide shield (310) while passing between the outer surface of the central swirl guide (600) and the inner wall of the discharge tube (200), and when the reverse swirl enters the interior of the central swirl guide (600), the reverse swirl is further guided toward the center of the plasma by the plasma center target swirl guide (700), and accordingly, the discharge gas moving in the reverse swirl comes into contact with a higher temperature plasma, and for example, if the discharge gas is methane, the thermal decomposition efficiency by the plasma can be increased.

[0081] The description of the presented embodiments is provided so that any person skilled in the art may use or practice the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments without departing from the scope of the present invention. Thus, the present invention is not limited to the embodiments presented herein, but should be interpreted in the broadest possible scope consistent with the principles and novel features presented herein.

Claims

Claim 1 A microwave plasma torch comprising: a rectangular waveguide for transmitting electromagnetic waves; a cylindrical discharge tube including a swirl guide shield formed at one end of the cylindrical shape with an inclination toward the central axis of the cylindrical shape as it moves away from the one end, and a plasma discharge port on the opposite side of the swirl guide shield, wherein the space between the swirl guide shield and the plasma discharge port is vertically penetrated by the rectangular waveguide to allow electromagnetic waves to flow into the interior; and a plurality of discharge gas injectors installed tangentially to the discharge tube from the direction of the plasma discharge port to inject discharge gas into the interior of the discharge tube in a swirl, wherein the discharge gas is injected in a swirl toward the swirl guide shield along the inner wall of the discharge tube, and then moves toward the plasma discharge port in a swirl that narrows the radius of rotation as it comes into contact with the inclined inner surface of the swirl guide shield, thereby more narrowly surrounding the center of the discharge tube. Claim 2 A microwave plasma torch according to claim 1, wherein the discharge tube is a dielectric in the portion penetrating the right-angle waveguide and the swirl guide shield is made of a metal material. Claim 3 In paragraph 2, the above dielectric is quartz, a microwave plasma torch. Claim 4 A microwave plasma torch according to claim 1, wherein the plurality of discharge gas inlets are installed in the tangential direction and inclined upward at a certain angle. Claim 5 A microwave plasma torch according to claim 4, wherein the inclination angle of the plurality of discharge gas inlets is 45 degrees or more and 90 degrees or less. Claim 6 A microwave plasma torch according to claim 1, further comprising a discharge tube center penetration inlet through which a gas or material to be processed is introduced through the center of a swirl guide shield portion coaxial with the cylindrical central axis, wherein the material to be processed is processed while passing through the inner swirl that more narrowly surrounds the center of the discharge tube. Claim 7 In claim 6, the discharge tube comprises a central swirl guide tube of dielectric material provided in its inner center, the central swirl guide tube is provided with a diameter such that its outer surface is spaced apart from the inner surface of the discharge tube, the diameter being capable of accommodating a swirl that more narrowly surrounds the center of the discharge tube, the end of the central swirl guide tube facing the swirl guide shield is spaced apart from the inner surface of the swirl guide shield, and the swirl that more narrowly surrounds the center of the discharge tube and the gas or material to be processed are guided and moved toward the plasma discharge port along the inner passage of the central swirl guide tube, a microwave plasma torch. Claim 8 A microwave plasma torch according to claim 7, wherein the central swirl guide tube is formed such that its diameter decreases as it moves in the opposite direction from the end facing the swirl guide shield. Claim 9 A microwave plasma torch according to claim 7, wherein the central swirl guide tube includes a plasma central target swirl guide inside, and the plasma central target swirl guide is formed such that one end is connected to the end of the central swirl guide tube facing the swirl guide shielding part, and the diameter decreases as it goes in the opposite direction from the end facing the swirl guide shielding part. Claim 10 In claim 1, the microwave plasma torch, wherein the swirl guide shield is dome-shaped. Claim 11 In claim 1, the microwave plasma torch, wherein the swirl guide shield is in the shape of a triangular pyramid. Claim 12 A microwave plasma torch according to claim 8 or 9, further comprising: a cylindrical cooling jacket covering a portion of the discharge tube exposed to the outside of the right-angle waveguide; a cooling water inlet penetrating the side of the cooling jacket at the direction of one end of the cooling jacket; and a cooling water outlet penetrating the side of the cooling jacket at the opposite side of the location of the cooling water inlet.

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